Физический факультет
Московский государственный университет имени М. В. Ломоносова
The Alpha Magnetic Spectrometer (AMS) is a general-purpose high-energy particle detector that was deployed to the International Space Station (ISS) on May 19, 2011 to perform a unique longduration mission of fundamental physics research from space. Among the scientific goals of AMS are the search for Dark Matter and Antimatter, the study of the propagation of cosmic rays and the exploration of new scientific phenomena that cannot be achieved on ground-based experiments. After ten years of operation in space, AMS has collected more than 180 billion cosmic ray events and provided accurate measurements of electrons, positrons, protons, antiprotons, and nuclei with energies of several TeV during nearly a complete solar cycle
Показать АннотациюPossible existence of antimatter in our Galaxy, in particular of antistars is discussed and the mechanism of their creation is decribed.
Показать АннотациюThe China Seismo-Electromagnetic Satellite (CSES-01), in orbit since February 2, 2018, is the first element of an extended constellation of LEO (Low-Earth Orbit) satellites, dedicated to monitoring perturbations of electromagnetic fields, plasma and charged particle fluxes induced by natural sources and artificial emitters in the near-Earth space. The Limadou Collaboration, which is the Italian branch of the aforementioned mission, designed and built one of the nine payloads on board the satellite, i.e. the High-Energy Particle Detector (HEPD-01). HEPD-01 is optimized to detect electrons (3-100 MeV), protons (30-300 MeV), and light nuclei (up to a few hundreds of MeV) with a high energy resolution and a wide angular acceptance. The very good capabilities in particle identification together with the orbit of CSES01 make HEPD-01 well suited for measuring galactic particle fluxes and their solar modulation, and also for space weather purposes. In this work, we present some results obtained with HEPD-01 during the first three years in flight, including the observation of the August 2018 geomagnetic storm and the galactic cosmic-ray hydrogen spectra in the 40–250 MeV range.
Показать АннотациюShort history and modern status of muon puzzle in cosmic rays of very high energies are described. Possible reasons of muon puzzle appearance are discussed. Some experimental ways of muon puzzle solution are considered. One of them is the measurement of energy characteristics of muons, which give the contribution to the observed excess of muon bundles at very high energies. Preliminary results of measurements of muon bundle energy deposit at large zenith angles are analysed.
Показать АннотациюUpcoming µ ↔ e experiments promise exceptional sensitivity to a few key processes, reaching Branching Ratios <∼ 10−16 for µ → e conversion on Aluminium. Upcoming τ ↔ l searches will probe many processes down to BR ∼ 10−9 . In an EFT context, we show that some combinations of µ → τ and τ → e interactions could induce detectable µ → e while remaining out of reach to τ ↔ l searches.
Показать АннотациюI review possible explanations of the muon g-2 anomaly in models with extended Higgs and matter sectors, focusing on extensions of the standard model and the two Higgs doublet model with vectorlike leptons. Predictions of these models, namely the modifications of muon Yukawa and gauge couplings, that can be searched for at the LHC and future colliders, are summarized. I also discuss striking predictions for di-Higgs and tri-Higgs signals at a muon collider that can be tested even at very low energies. Furthermore, I briefly comment on other interesting features and signatures of models with extended Higgs sector and vectorlike matter.
Показать АннотациюThe Mu2e experiment, currently under construction at Fermilab, will search for the neutrinoless conversion of a muon into an electron in the field of an aluminum atom. A clear signature of this charged lepton flavor violating two-body process is given by the monoenergetic conversion electron of 104.97 MeV produced in the final state. The experiment will need 3-5 years of data-taking to achieve a factor of 104 improvement on the current best limit on the conversion rate. After a short description of the experimental apparatus, the experiment’s sensitivity and discovery potential will be presented.
Показать АннотациюA summary and outlook of the theory motivations and status of searches for lepton flavour violation (LFV) in meson and baryon (semi-)leptonic decays is provided. The contribution is structured as follows: (i) A short overview of b → s as well as b → c data; (ii) General arguments for pursuing LFV in b-hadron decays; (iii) Additional arguments for possible LFV signatures in other meson decays, in particular of kaons. Emphasis is on a presentation accessible to a wider public, describing the underlying motivation and physics arguments with a minimum of equations.
Показать АннотациюAn electroweak (EW) sector of the Minimal Supersymmetric Standard Model (MSSM) with masses of a few hundred GeV can account for variety of experimental data, assuming the lightest neutralino to be the lightest supersymmetric (SUSY) particle: the non-observation at the LHC, searches owing to their small production cross sections, the results for the (upper limit of the) Dark Matter (DM) relic abundance and the DM Direct Detection (DD) limits. Such a light EW sector can in particular explain the reinforced 4.2 σ discrepancy between the experimental result for (g − 2)µ, and its Standard Model (SM) prediction. Using the improved limits on (g − 2)µ, we review the predictions for the future prospects of the DD experiments. This analysis is performed for several different realizations of DM in the MSSM: bino, bino/wino, wino and higgsino DM. We find that higgsino, wino and one type of bino scenario can be covered by future DD experiments. Mixed bino/wino and another type of bino DM can reach DD cross sections below the neutrino floor. In these cases future collider experiments must cover the remaining parameter space.
Показать АннотациюThe Any Light Particle Search (ALPS II) is a light shining through a wall (LSW) experiment searching for axion-like elementary particles in the sub-eV mass range, which are motivated by astrophysics and cosmology and fulfill the requirements for being dark matter. ALPS II aims to measure an axion-to-photon coupling of 2 × 10−11 GeV−1 , which is several orders of magnitude better than that of previous LSW experiments and will thus investigate a new parameter range. The increased performance is achieved by enhancing the magnetic field interaction length to 2 × 106 m and by amplifying the signal in an optical cavity on each side of a light-tight barrier. The expected signal is in the order of 1 photon per day, which will be measured by photon detectors with very low dark count rates of O(10−6 Hz). This article gives a technical overview on the experiment design, previous and ongoing investigations and the current status with focus on the single photon detection.
Показать АннотациюIn view of the current tensions observed in B-meson decays, we discuss the possibility of extending the Standard Model with scalar leptoquarks when the avor structure is parametrized in terms of Froggatt-Nielsen charges. The Standard Model fermion mass and mixing hierarchies together with the B-anomalies restrict to only two possible solutions for the charges. Such a setup predicts sizable contributions to several other decays whose branching ratios are close to the current experimental limits.
Показать АннотациюA bottom-up approach has been adopted to identify a avour model that agrees with present ex- perimental measurements. The charged fermion mass hierarchies suggest that only the top Yukawa term should be present at the renormalisable level. The avour symmetry of the Lagrangian includ- ing the fermionic kinetic terms and only the top Yukawa is then a combination of U(2) and U(3) factors. Lighter charged fermion and active neutrino masses and quark and lepton mixings arise con- sidering speci c spurion elds. The associated phenomenology is investigated and the model turns out to have almost the same avour protection of the Minimal Flavour Violation, in both quark and lepton sectors. Promoting the spurions to be dynamical elds, the associated scalar potential is also studied and a minimum is identi ed such that fermion masses and mixings are correctly reproduced.
Показать АннотациюWe brie y summarize the current status and plans of a sample of charged lepton avor violation experimental e orts, emphasizing muon-based experiments.
Показать АннотациюWe describe the discovery of the odderon, by the D0 and TOTEM Collaborations by comparing elastic di erential cross sections measured in pp and pp interactions at high energies.
Показать АннотациюWe discuss probing of the massive axion-like particles (ALPs) by two radio-frequency (RF) cylindrical cavities. We optimize the design the of these cavities to perform the e ective strategy for the ALPs searches. In particular, we study the radiation pattern and energy density distribution of the ALP eld produced in the cavity by two electromagnetic modes. We also discuss the sensitivity of the proposed experimental setup to examine ALPs.
Показать АннотациюWe discuss some recent results on physics beyond the Standard Model, including constraints on sterile neutrinos, charged lepton avor violation, and baryon number violation.
Показать АннотациюDipole interactions encode a rich variety of phenomena, such as radiative decays and Electric Dipole Moments (EDMs) in both quark and lepton sectors, which probe physics beyond the Standard Model (SM) up to very high energy scales. Due to renormalization, non-dipole operators mix into dipole ones, thus possibly generating observable e ects that can be investigated by those same phenomena. I consider four-fermion contact interactions for which the leading order mixing into dipoles happens at two-loops (i.e., when mixing at one-loop vanishes) and for which this mixing can avoid small Yukawa couplings, and then explore the phenomenological consequences for avour and CP Violation (CPV) coming from New Physics.
Показать АннотациюThe Tile Calorimeter (TileCal) is a sampling hadronic calorimeter covering the central region of the ATLAS experiment. TileCal uses steel as absorber and plastic scintillators as active medium. The scintillators are read-out by the wavelength shifting bres coupled to the photomultiplier tubes (PMTs). The analogue signals from the PMTs are ampli ed, shaped, digitized by sampling the signal every 25 ns. Each stage of the signal production is monitored and calibrated to better than 1% using multistage calibration systems. The performance of the calorimeter has been measured and monitored using calibration data, cosmic ray muons and the large sample of proton-proton collisions acquired during LHC Run II. The High-Luminosity phase of LHC, delivering ve times the LHC nominal instantaneous luminosity, is expected to begin in 2027. TileCal will require new electronics to meet the requirements of a 1 MHz trigger, higher ambient radiation, and to ensure better performance under high pileup conditions. Changes to the electronics will also contribute to the data integrity and reliability of the system. New electronics prototypes were tested in laboratories as well as in beam tests. Results of the calorimeter calibration and performance during LHC Run II are summarized, the main features and beam test results obtained with the new front-end electronics are also presented.
Показать АннотациюThe BABAR detector collected a sample of 122 million (3S) mesons, corresponding to an integrated luminosity of 28fb1, operating the PEP-II e+e collider at a center-of-mass energy of about 10.355GeV . This sample is the largest ever collected at that energy and provides unique opportunities to test several aspects of the Standard Model. We report on a precision measurement of the ratio R(3S) = BF((3S)! + ) BF((3S)!+) . The result is in agreement with the Standard Model prediction and its uncertainty is almost an order of magnitude smaller than the only previous measurement reported by the CLEO collaboration. We also present a search for the Lepton Flavour Violating decays (3S) ! e, unobservable in the SM, but predicted to be enhanced in several new physics extensions
Показать АннотациюA wide programme of heavy avour production studies are performed with the ATLAS detector[1]. This paper covers recent results in measurements of J= and (2S) production at high pT at 13 TeV, studies on the production of B c =B production cross-section and pentaquark searches in 0b ! J= pK are presented as well.
Показать АннотациюRecent results on e +e − annihilation to hadrons below 2 GeV obtained at the SND experiment at the VEPP-2000 collider are presented. In particular, we discuss measurements of the e +e − → π +π − and e +e − → nn¯ cross sections, and study of the processes e +e − → π +π −π 0 , K+K−π 0 , ηπ0γ, ηηγ, ωπ0 , and pp¯.
Показать АннотациюWe report recent results from ALICE on the direct photon and neutral meson measurements in pp, p-Pb and Pb-Pb collisions at several energies and compare them to model calculations.
Показать АннотациюThe paper presents the results on 0; ;K;K, and p(p) production in small collision systems at p sNN = 200 GeV as a function of transverse momentum at midrapidity (jj < 0:35) measured by the PHENIX experiment.
Показать АннотациюThis contribution presents new results of NA61/SHINE on multiplicity and net-charge uctua- tions measured with higher-order moments. It includes both rapidity dependence in p+p interac- tions as well as system size and energy dependence with Be+Be and Ar+Sc interactions. Obtained results are compared with the available data from other experiments and from models.
Показать АннотациюThis paper, based on the invited talk at the 20th Lomonosov Conference of Elementary Particle Physics, provides short overview of the Higgs physics program at future linear colliders as Higgs factories. Keywords: Linear Collider, Higgs
Показать АннотациюMeasurements of processes involving single top quarks or top-quark-antiquark pairs are of major importance to check the predictions of the Standard Model or to provide sensitivity to new physics beyond the Standard Model. In the recent years, the ATLAS experiment at the Large Hadron Collider performed precise measurements of top-quark related properties and also measured more complex Standard Model processes associated with top quarks, which have typically very low cross sections compared to the main production modes at the Large Hadron Collider. On this subject, some of the most relevant results released by the ATLAS collaboration in 2021 are presented: the inclusive and di erential cross-section measurement of top-quark-antiquark production in associa- tion with a Z boson, the cross-section measurement of four top-quark production, the ducial and di erential measurement of the top-quark-antiquark cross section with high transverse momenta of the top quarks, as well as the polarisation measurement of single top quarks (antiquarks) produced in the t-channel.
Показать АннотациюThe Standard Model (SM) of particle physics is the most advanced theory describing the be- haviour and interactions of elementary particles. Despite passing an impressive amount of ex- perimental tests, several deviations from the SM predictions have been observed in recent years in measurements of observables related to rare b-hadron decays, prompting great interest and motivating further investigations. A collection of selected recent results obtained by the LHCb collaboration [1] on the study of rare b-hadron decays is presented in these proceedings.
Показать АннотациюFASER is a small experiment designed to search for light and weakly-coupled particles during Run-3 of the LHC. Such particles, predicted in many extensions of the Standard Model, may be copiously produced along the beam collision axis and travel a signi cant path before decaying to detectable particles. FASER, conveniently located 480m downstream of the interaction point of the ATLAS experiment, is designed to look for such signatures. The FASER location, its detector layout, and commissioning towards data-taking in 2022 are reviewed.
Показать АннотациюThe PANDA experiment is one of the major projects in preparation at the upcoming Facility for Antiproton and Ion Research (FAIR) in Darmstadt/Germany. A multipurpose high energy physics detector is currently under construction and will be operated at the High Energy Storage Ring (HESR) of FAIR. The physics program includes hadron spectroscopy, search for charm and strangeness in nuclei, hypernuclear physics, nucleon structure and other QCD topics. In this report, some important aspects of the planned physics program of the PANDA experiment are described.
Показать АннотациюWe will review the most recent results on hadron spectroscopy at the LHCb experiment at CERN. The LHCb experiment is a single-arm forward spectrometer with excellent tracking and particle identi cation capabilities. With its high luminosity, the experiment has proven to be a very proli c player in the search and observation of new states (both conventional and exotic) in the recent years.
Показать АннотациюI will review the motivation and the general features of experiments devoted to testing fundamental laws with antimatter at low energies.
Показать АннотациюCentrality is a key parameter for de ning the collision system size in relativistic heavy-ion col- lisions. A procedure to determine the centrality of collisions with the Multi-Purpose Detector (MPD) at NICA is presented. Relation between impact parameter of the collision and centrality classes is extracted using multiplicity of produced charged particles.
Показать АннотациюThe Fermilab Muon g-2 experiment measures the muon anomalous magnetic moment with high precision. Together with recent improvements on the theory front, the rst results of the experiment con rm the long-standing discrepancy between the experimental measurements and the Standard Model predictions. The observed value of a(FNAL) = 116 592 040(54)1011 (0.46 ppm), combined with the previous experimental measurement, results in a discrepancy of (251 59) 1011 with the theoretical prediction, corresponding to 4:2 . This note presents the rst results, the current status and the future prospects of the Muon g-2 experiment at Fermilab.
Показать АннотациюThe highlights of the latest results for the search for exotic physics signatures at the Compact Muon Solenoid (CMS) experiment are presented. These include signatures for heavy mass res- onances, long-lived particles and leptoquarks predicted by theories beyond the standard model (BSM).
Показать АннотациюA search for heavy neutral lepton (N) production in K+ ! +N and K+ ! e+N decays is carried out by the NA62 experiment using the data collected in 2016{2018. The K+ ! +N results are expressed as upper limits of O(108) of the neutrino mixing parameter jU4j2 for N masses in the range 200{384 MeV/c2 and lifetime exceeding 50 ns. From the K+ ! e+N analysis, upper limits for neutrino mixing matrix element jUe4j2 are established near the level of 109 over most of the accessible heavy neutral lepton mass range 144{462 MeV/c2, with the same assumption about the heavy lepton lifetime.
Показать АннотациюIn this report we summarized an overview of the additional Higgs boson searches, based on the data collected by the CMS experiment in proton-proton collision by the CERN LHC. The results includes the Run-2 data taking period corresponding to an integrated luminosity of 137 fb1 at the center-of-mass energy of 13 TeV. A Model-independent upper limit at 95% con dence level on various branching fraction and/or process production cross-section times branching fraction are reported.
Показать АннотациюWe suggest a procedure for detecting the lightest glueball in a head-on collision of photons whose center-of-mass energy in the range 1:32 GeV. A phenomenological basis for this suggestion is recent evidence for scattering of light by light in LHC experiments. With this evidence, the cross section of the lightest glueball creation in collisions is estimated to be 60 nb. The predominant mode of the lightest glueball decay, predicted from the gauge/gravity duality, is the decay into 00. Since the 0 decays into +, a drastic increase of the ++ yield is expected as the center-of-mass energy approaches the mass of the lightest glueball. It is this fact which will be the unique signature of the lightest glueball detection.
Показать АннотациюThis report presents the recent results by the CMS Collaboration on the electroweak sector of the Standard model, including single boson and Drell-Yan production, as well as multiboson processes. Detailed studies included measurements of differential cross sections and many other observables, such as asymmetries, ratios for lepton flavor universality, anomalous gauge couplings, etc.
Показать АннотациюThe paper presents recent PHENIX results on hadron production in heavy ion collisions. Com- parison of light hadron (0; ;Ks;K;K; (p + p)=2; ; ; !) nuclear modi cation factors in Au+Au, Cu+Au collisions at p sNN =200 GeV and U+U collisions at p sNN =192 GeV will be discussed.
Показать АннотациюThe CMS measurements of inclusive jet production and of top quark-antiquark production in proton-proton collisions at the LHC at the center of mass energy of 13 TeV are used together with the data of inclusive deep inelastic scattering to extract the parton distribution functions in the proton, the top quark mass and the strong coupling constant. Using standard model predictions, the analysis at NNLO results in the most precise determination of the strong coupling constant at hadron collider. In an alternative analysis, the standard model is extended with effective couplings for 4-quark contact interactions, leading to the first simultaneous extraction of the standard model parameters and the Wilson coefficients of contact interactions using the LHC data.
Показать АннотациюThe elliptic collective ow (v2) is one of the important observables sensitive to the transport properties of strongly interacting matter created in relativistic heavy-ion collisions. The perfor- mance of MPD detector at NICA for v2 measurements using two- and four-particle correlation methods is studied with simulations of Au+Au collisions at p sNN = 7.7, 11.5 GeV.
Показать АннотациюThe investigation of rare production of the pair Bc-meson in the Higgs boson decay is presented. Relativisic amplitudes and decay widths are constructed on the basis of relativistic quark model with the account of the relative motion of heavy quarks.
Показать АннотациюFree Electron Laser (FEL) facilities provide broadly tunable and highly coherent photon beams. These machines still have an unexplored potential and development. The XLS-CompactLight design aims at a flexible Hard plus Soft X-ray FEL facility exploiting the latest concepts in terms of short period magnetic undulators, paving the road towards more compact photon sources.
Показать АннотациюMulti-Purpose Detector (MPD) experiment at NICA collider has the potential of discoveries in the QCD phase diagram region with high net-baryon densities and moderate temperatures. Anisotropic elliptic ow v2 ow is one of the key observables to study the properties of matter created in heavy-ion collisions. The application of two- and three-particle correlation scalar product methods for elliptic ow measurements in MPD is discussed in this work.
Показать АннотациюWe present a selection of recent results by the CMS collaboration on heavy-ion physics.
Показать АннотациюOn the statistics of ∼ 1.7 · 108 interactions of positively charged kaons on copper nuclei coherent events of the K+π0 - system production are selected. Cross sections for the Coulomb, coherent strong components and their interference in the region of K∗(892)-meson are measured. When studying the mass spectrum of the K+π0 - system, an effect is found, which can be interpreted as the interference of the chiral anomaly and the K∗(892) s - channel amplitudes. This gives an estimate for the ratio of the observed amplitude of the chiral anomaly to the theoretical one: Aexp/Ath = 0.90 ± 0.24 (stat.) ±0.3 (syst.).
Показать АннотациюWe perform the rst polarisation study [1] at next-to-next-to-leading order (NNLO) QCD for the leptonic signature of the diboson production process (pp ! e+e), in the ducial setup inspired by experimental measurements at ATLAS. We present the results and investigate NNLO e ects arising in di erential distributions. Calculation is performed within the framework of double- pole approximation.
Показать АннотациюThe KOTO experiment at the J-PARC 30GeV Main Ring is dedicated to search for the rare decay KL → π0νν. This mode directly breaks the CP symmetry and is highly suppressed in the Standard Model (SM). In addition, the theoretical uncertainties on the decay is only a few percent. Those features make this decay one of the best probes to search for new physics beyond the SM. We have been accumulating physics data since 2013 and we had finalized the analysis with the dataset taken in 2016-2018. In the analysis, we found charged kaons contained in the neutral beam could become a serious background source. Thus, we have installed a new counter to detect the charged kaons and resumed physics data taking. In this parper, we report the results of the 2016-2018 analysis and the status of recent data taking.
Показать АннотациюWe review four most precise measurements from charm physics program at the LHCb during 2021. These include the rst observation of non-zero mass di erence between neutral charm-meson eigenstates, the world most precise determination of both time-dependent and time-integrated charge-parity.
Показать АннотациюNew results of analysis of K0S -meson spectra in Au + Au collisions obtained by the STAR Collaboration at RHIC using the z-scaling approach are presented. The spectra were measured over a wide range of collision energy √ sNN = 7.7−200 GeV, transverse momentum of produced particles and different centralities in the rapidity range |y| < 0.5. The self-similarity of the K0S spectra in z-presentation is demonstrated. The energy loss as a function of the collision energy and the transverse momentum of K0S meson for 0-5% centrality is estimated.
Показать АннотациюIn recent years there was signi cant progress in the B-physics studies including those at the Large Hadron Collider (LHC). This report will focus on two recent results in B-physics from the CMS collaboration.
Показать АннотациюCP violation is one of Sakharov’s conditions for the matter-antimatter asymmetry of the Universe. The experimentally observed size of CP violation is insufficient to account for this. Is CP violated in the Higgs sector? Could the SM-like Higgs boson be a mixture of CP even and CP odd states of an extended Higgs sector? With what precision could such effects be measured at future electron-positron colliders? These questions will be discussed in the light of the latest studies at ILC.
Показать АннотациюThe electroweak production of multi-boson processes are a powerful tool to probe the Standard Model. The processes are sensitive to gauge boson self-interactions, which is related to non-Abelian structure of the electroweak interactions. Such processes also o er discovery opportunities. In this talk the latest results are presented, including ZZjj, Z jj, and WWW processes.
Показать АннотациюWe review the experimental progress on the study of the quarkoniumlike states, also known as XYZ states. We give a general review and then focus on the new experimental results on the X(3872), the Y (4260) and Y (4660), and the charged charmoniumlike Zc and Zcs states. The observations suggest that we did observe hadronic molecules and we also observed hadronic states with some other quark configurations.
Показать АннотациюThe decay K+ → π+νν¯, with a very precisely predicted branching ratio of less than 10−10, is among the best processes to reveal indirect effects of new physics. The NA62 experiment at CERN SPS is designed to study the K+ → π+νν¯ decay and to measure its branching ratio using a decay- in-flight technique. NA62 took data in 2016, 2017 and 2018, reaching the sensitivity of the Standard Model for the K+ → π+νν¯ decay by the analysis of the 2016 and 2017 data, and providing the most precise measurement of the branching ratio to date by the analysis of the 2018 data. The final result of the BR(K+ → π+νν¯) measurement from the analysis of the full 2016-2017-2018 data set is presented, and future plans and prospects reviewed.
Показать АннотациюThe DAMA/LIBRA observation of an annual modulation in the detection rate compatible with that expected for dark matter is one of the most puzzling results in the present particle physics scenario. This signal is in strong tension with the negative results of other experiments. However, until recently a direct comparison using the same target material (NaI(Tl)) was lacking. ANAIS (annual modulation with NaI Scintillators) is a dark matter direct detection experiment located at the Canfranc Underground Laboratory (LSC, Spain). Its main goal is to test in a model independent way the DAMA/LIBRA positive result. ANAIS-112, consisting of 112.5 kg of NaI(Tl) scintillators, was installed at the LSC in 2017 and since then is taking data smoothly with excellent performances. Here we present the results of the annual modulation analysis corresponding to three years of ANAIS data. These results are compatible with the absence of modulation and in tension with DAMA/LIBRA result. Moreover, they support our goal of reaching a 3 sensitivity to the DAMA/LIBRA result with about 5 years of data.
Показать АннотациюThe DArk Matter Particle Explorer (DAMPE) is a satellite orbiting at 500 km altitude in a Sun-synchronous orbit, taking data from its launch on December 17th, 2015. DAMPE is composed by several particle detectors, working together to identify incoming particles and nuclei. Main goals of the DAMPE space mission are: study of cosmic-rays and electron-positron energy spectra, gamma-ray astronomy, and indirect dark matter search. The main results achieved by DAMPE will be presented in this work.
Показать АннотациюDespite signi cant searches for dark matter, experiments have so far produced no results. The latest generation of nuclear emulsions, Nano Imaging Trackers (NIT), has nanometric precision and was created speci cally for a directional DM search. The NIT emulsion is used as both the Weakly Interactive Massive Particle (WIMP) target and the nanometric-accuracy tracking device in the Nuclear Emulsion WIMP Search with Directional Measurement (NEWSdm) experiment, which is housed in the Gran Sasso underground laboratory in Italy. Detector design, the super-resolution readout technology, expected backgrounds, physics potential, and near-future plans are all discussed here.
Показать АннотациюIn the conventional cosmology masses of the stable supersymmetric relics, candidates for the dark matter (DM) particles, should be typically below 1 TeV. This is in con ict with the LHC bounds on the low energy SUSY. However, in R2-gravity the masses of the stable particles with the interaction strength typical for SUSY could be much higher depending upon the dominant decay mode of the scalaron. We discuss the bounds on the masses of DM particles for the following dominant decay modes: to minimally coupled massless scalars, to massive fermions, and to gauge bosons.
Показать АннотациюThe long-standing model-independent annual modulation effect measured by DAMA deep un- derground at the Gran Sasso National Laboratory (LNGS) of the I.N.F.N. using different experi- mental configurations is summarized also including the results of two new annual cycles collected by DAMA/LIBRA-phase2; the total exposure of DAMA/LIBRA–phase2 over 8 annual cycles is 1.53 ton × yr. The evidence of a signal that meets all the requirements of the model independent Dark Matter (DM) annual modulation signature is further confirmed at 11.8 σ C.L. in the energy region (1–6) keV. In the energy region between 2 and 6 keV, where data are also available from DAMA/NaI and DAMA/LIBRA–phase1, the achieved C.L. for the full exposure (2.86 ton × yr) is 13.7 σ.
Показать АннотациюThe extreme conditions in Neutron Stars make them ideal test facilities for fundamental inter- actions. A Neutron Star can capture Dark Matter via scattering. As a result of the scattering, Dark Matter kinetic energy is transferred to the star. An observational consequence of this can be the warming of old neutron stars to near-infrared temperatures. Di erent approximations or simpli cations have been applied to previous analyses of the capture process. In this article, we summarise a signi cantly improved treatment of Dark Matter capture, which properly accounts for all relevant physical e ects over a wide range of Dark Matter masses. Among them are grav- itational focusing, a fully relativistic scattering treatment, Pauli blocking, neutron star opacity and multiple scattering e ects. This paper cites general expressions that allow the capture rate to be computed numerically, and simpli ed expressions for particular types of interactions or mass regimes, which greatly increase the eciency of computation. As a result of our method, we are able to model the scattering of Dark Matter from any neutron star constituent as well as the capture of Dark Matter in other compact objects. Our results are applied to scattering of Dark Matter from neutrons, protons, leptons and exotic baryons. For leptonic targets, we nd that a relativistic description is essential. In our analysis of the capture of Dark Matter in Neutron Stars, we include two important e ects that are generally ignored by most studies. Because the scattering of Dark Matter with nucleons in the star exhibits large momentum transfers, the nucleon structure must be considered via momentum-dependent hadronic form factors. Moreover, because of the extreme densities of matter inside Neutron Stars, we should consider nucleon interactions instead of assuming all nucleons are a perfect Fermi gas. Taking into account these e ects results in a decrease of up to three orders of magnitude in the dark matter capture rate. The potential Neutron Star sensitivity to DM-lepton scattering cross sections is much greater than electron-recoil experiments, particularly in the sub-GeV regime, with a sensitivity to sub- MeV DM well beyond the reach of future terrestrial experiments. We also present results for DM- Baryon scatterings in Neutron Stars, where the sensitivity is expected to exceed that of current DD experiments for spin-dependent cases across the entire mass range, and for spin-independent cases across the high and low mass range.
Показать АннотациюLow background anisotropic detectors can o er a unique way to study those Dark Matter (DM) candidate particles able to induce nuclear recoils through the directionality technique. This approach is based on studying the correlation between the nuclear recoils' direction and the Earth motion in the galactic rest frame. Thanks to the anisotropic features of such detectors, a signal, induced by the DM candidates, is expected to change with a particular behaviour as a function of the sidereal time. The ZnWO4 has unique features and it is an excellent candidate for the purposes. Both the light output and the scintillation pulse shape depend on the impinging direction of heavy particles (p, , nuclear recoils, etc.) with respect to the crystal axes and can supply two independent modes to study the directionality and to discriminate the = radiation (that does not give rise to any anisotropic e ects). In this work, the measurements to study the anisotropic response of a ZnWO4 scintillation detector to particles and to nuclear recoils, induced by neutron scattering, are brie y summarised.
Показать АннотациюSearches for Dark Matter suggest that it couples to ordinary matter only very weakly and possibly only through the Higgs or other scalar bosons. On the other hand, neutrinos might not couple to the Higgs boson directly, but only through a loop of Dark Matter particles, which would naturally explain the small neutrino masses. We demonstrate that current experimental constraints on such a \scotogenic" scenario allow to make the linear dependence of the lightest neutrino mass on the dark sector-Higgs coupling explicit, so that a measurement by the KATRIN experiment would directly determine its value.
Показать АннотациюThe paper reports the latest results obtained in PHELEX. The focus of work is on diurnal variations of the count rate of single electrons emitted from a cathode as a way to prove that the observed effect is really from dark photons. The authors outline their plans for the future.
Показать АннотациюWe argue that the search for dark vector boson through e+e ! Zd can determine the Lorentz structure of Zdl+l couplings with the detection of leptonic decays Zd ! l+l. We assume a general framework that the dark vector boson interacts with ordinary fermions through vector and axial-vector couplings. Taking l , we study the correlation between Zd angle relative to e beam direction in e+e CM frame and angle relative to the boost direction of Zd in Zd rest frame. This correlation is useful for probing the Lorentz structure of Zdl+l couplings. We discuss the measurement of such correlation in Belle II detector.
Показать АннотациюA fast progress in the observational technologies in astrophysics provides the unique possibility for detailed observations of black holes in the nearest future. It would be possible to verify general relativity and its numerous modifications in the strong field limit by using observational data from the advanced cosmic interferometric observatories. We review the modeled images of the rotating black hole in di erent appropriate cases: the luminous distant background, the thin accreting disk and the luminous moving hot spots in relativistic jets along the black hole rotation axis.
Показать АннотациюInformation of a blackhole inside has a long history. After mentioning the original information idea, we show that local gauge invariance can connect the inside information to the outside surface area due to the Sperner's lemma.
Показать АннотациюEquation for gravitational wave (GW) propagation over arbitrary curved spacetime is derived in the presented work. Two new terms are found which absent in the conventional homogeneous and isotropic Friedmann cosmology. In conclusion we emphasize that these new terms can significantly change the character of solutions and assume that one of the terms may be the cause of relic GW amplitude suppression.
Показать АннотациюThe gravitational interaction of spinless relativistic particle and in nitely thin cosmic string is considered within the classical linearized-theory framework. We compute the reciprocal action of the particle on the cosmic string. We derive the retarded string's excitation, which includes the longitudinal (with respect to the unperturbed-particle motion) z and totally-transverse (y ) string perturbations.
Показать АннотациюPrecise observations of trajectories of bright stars near the Galactic Center give an opportunity to evaluate the gravitational potential since bounded stars move along the trajectories which are very close to elliptical ones. Since the Sgr A* position is very close to foci of the bound trajectories astronomers conclude that the Newtonian potential is a very good approximation for available observational data. In 2018 { 2019 GRAVITY and Keck collaborations found that gravitational redshifts for S2 star near its pericenter passage are tting by the rst post-Newtonian correction of General Relativity (GR). In 2020 the GRAVITY collaboration found that the Schwarzschild precession for S2 star is in accordance with GR predictions. Therefore, GR successfully passed important test for the Galactic Center and astronomers got new con rmations of the universality of gravity law predictions. In last years we considered several versions of alternative theories of gravity and showed that observations of bright stars give an opportunity to constrain parameters of such theories. Choosing suitable models for galactic centers is an extremely important astrophysical task. The Galactic Center is the closest object for astronomers for which a large amount of observational data has been obtained. Observations of the trajectories of bright stars in the vicinity of the Galactic Center have shown that there is a compact distribution of matter, which is interpreted as a supermassive black hole with a mass of the order of M = 4:3 106 M . In 2015, Runi, Arguelles, Rueda (RAR) proposed a model for the distribution of dark matter with a dense core and a diluted halo, and later the authors declared that there is not a supermassive black hole, but a core of dark matter with constant density in the Galactic Center. In 2020 { 2021, claims were made that the RAR model could better t the trajectories of bright stars than the traditional model involving a supermassive black hole. The RAR-approach was actively promoted as a reliable model for the Galactic Center. In our work, we showed that the trajectories of stars considered in the framework of the RAR model are elliptical, but the properties of these trajectories are di erent from observed ones and the conventional model of the Galactic Center, which includes the supermassive black hole, is preferable.
Показать АннотациюThe article presents the latest results with the experiment of the Large Volume Detector located in the Gran Sasso Laboratory at the depth of 3650 m.w.e. LVD has been in operation since 1992 on the program a search for neutrino bursts from stellar core colapses, variations of the cosmic ray muon flux, and investigations of background sources at detecting rare events. According to the data of the LVD neutrino telescope for 29 years of operation (1992 - 2021), an experimental limitation on the frequency of neutrino bursts from gravitational collapses of stars in the Galaxy was obtained: less than 1 event in 12.6 years (f = 0.08 year−1) at a 90% confidence level.
Показать АннотациюThe search for neutrinoless double-beta decay (02 ), a hypothetical nuclear decay, is one of the major challenges of contemporary physic since its discovery would prove the non conservation of the lepton number and would give an answer to the question of neutrino nature (Dirac or Majorana particles). Starting from the scintillating bolometer technique (a scintillating cryogenic absorber embedding a 02 candidate coupled with a cryogenic light detector for dual heat-light readout), BINGO will search for this decay using the knowledge acquired so far by bolometric experiments with the addition of new methods and technologies to reduce drastically the background in the region of interest. BINGO will study two isotopes which have already shown their good suitability for this detection method: 100Mo and 130Te. The proposed solutions will have a high impact on next-generation bolometric tonne-scale experiments, like CUPID, to push further the sensitivity to the half-life of the process. In this contribution, we present the main axes of the project.
Показать АннотациюNuclear reactors are an essential source of neutrinos. In this proceeding, I review the past and current status of the research on neutrino oscillations using reactor neutrinos. I also present a promising idea for positron tagging that will potentially be a game-changer in the eld.
Показать АннотациюAn open question still involves the nature of neutrinos: are they equal to their anti-matter coun- terpart? The most promising way to test this Majorana nature of neutrinos is searching for the neutrinoless double beta decay (0 ), a hypothetical lepton number violating nuclear process. Furthermore, its observation would give an extraordinary insight into why our universe is predom- inantly composed of matter, which is another unsolved puzzle of cosmology and particle physics. Since 2011, the Gerda collaboration has searched for 0 of 76Ge by operating bare germanium detectors, enriched in the double-beta decaying isotope 76Ge, in liquid argon. Exploiting the com- bination of excellent energy resolution of germanium detectors and scintillating properties of argon, the Gerda experiment succeeded to achieve an unprecedented background-free regime. In Decem- ber 2019, after ful lling and exceeding the design goals of the experiment, data taking was stopped. No signal has been observed, hence a lower limit on the half-life of 0 in 76Ge has been set at T0 1=2 > 1:8 1026 years at 90% C.L.. The nal results of the Gerda experiment are discussed.
Показать АннотациюIn the DsTau (NA65) experiment at CERN SPS, an independent and direct way to study a tau neutrino production in high energy proton-nucleous interactions was proposed. The experi- mental method is based on a use of high resolution emulsion detectors for e ective registration of events with short lived particle decays. The motivation of the project, details of the experimental technique, and the rst results of the analysis of the data collected during test runs are presented.
Показать АннотациюThe Jiangmen Underground Neutrino Observatory (JUNO) is a 20 kton liquid scintillator detec- tor in a laboratory 700 m underground. An excellent energy resolution and a large fiducial volume offer exciting opportunities for addressing many important topics in neutrino and astro-particle physics. In this paper, the detector design, the physics prospects, and the subsystems of JUNO including the central detector, veto detector, calibration and JUNO-TAO will be introduced.
Показать АннотациюThe CUPID-Mo experiment, located in the Laboratoire Souterrain de Modane (France), is a demonstrator for the next generation ton-scale bolometric neutrinoless double beta decay exper- iment CUPID. CUPID-Mo is composed of 20 Li100 2 MoO4 scintillating bolometers, searching for 0 of 100Mo. With about one year of data acquisition we set a world leading limit on the half-life of 0 decay in 100Mo of T1=2 > 1:8 1024 yr at 90% C.I. This limit corresponds to an e ective Majorana mass m < (0:28{0:49) eV, dependent on the nuclear matrix element in the light Majorana neutrino exchange interpretation.
Показать АннотациюI present a comprehensive analysis of neutrino non-standard interactions (NSI) generated by new scalars in radiative neutrino mass models. To this end, I propose a new nomenclature for classifying radiative neutrino mass models: those containing at least one SM particle in the loop are designated as type-I radiative models, while those without SM particles in the loop are designated as type- II radiative models. In terms of NSI, type-I radiative models are the most intriguing, since the neutrino couples directly to an SM fermion (matter field) and a new scalar, creating NSI at the tree level, in contrast to type-II radiative models. I summarized the maximum possible NSI in all type-I radiative models after accounting for numerous theoretical and experimental restrictions. Additionally, I demonstrate that using light charged scalars in radiative models can result in a Glashow-like resonance feature in the UHE neutrino event spectrum at the IceCube neutrino observatory and its high-energy upgrade IceCube-Gen2, which can probe a sizable fraction of the allowed NSI parameter space. This talk is based on results obtained with K.S. Babu, Bhupal Dev, Anil Thapa and Yicong Sui and presented in hep-ph 1907.09498 and 1908.02779.
Показать АннотациюThe upgraded ND280 near detector of the T2K experiment will be able to reduce neutrino inter- action uncertainties using a con guration of detectors with full polar angle acceptance, improved spatial resolutions, neutron detection capabilities and reduced tracking thresholds. The status and parameters of a new 3D segmented scintillator detector SuperFGD and the expected physics output will be presented.
Показать АннотациюThe quest for 13 in the 2010's prompted new models for reactor e spectra, which marked the emergence of the reactor antineutrino anomaly. Several projects worldwide were designed to study the anomaly and investigate the possible existence of extra sterile neutrino families. This article reports an overview of the most recent experimental results on the search for reactor neutrino oscillation at very short baseline, and their implication in our current understanding of the reactor antineutrino anomaly and the sterile neutrino hypothesis.
Показать АннотациюDi erent constraints to the neutrino electric millicharge (NEM) have been obtained by con- sidering interactions such as the elastic neutrino-electron scattering (ENES). However, the great potential of the coherent elastic neutrino-nucleus scattering (CENS) in future reactor neutrino experiments could be an alternative to improve the current limits on the NEM. In this work we study the sensitivity of ENES and CENS interactions in reactor experiments to the neutrino charge through a combination of di erent experimental data. Bounds up to the order of 1014e are achieved from CENS at reactor neutrino experiments.
Показать АннотациюThe Deep Underground Neutrino Experiment (DUNE) will be a world-class, international new generation long-baseline neutrino experiment. To ensure high precision measurements of neutrino oscillation parameters, a sophisticated Near Detector (ND) complex made of three detectors is foreseen. One component, the System for on-Axis Neutrino Detection (SAND), will permanently be located on-axis while the other two will be moved at di erent o -axis positions. Besides monitoring the beam, SAND will contribute to keep systematic uncertainties on modeling of cross section, nuclear e ects and uxes under control.
Показать АннотациюOver the last decade breakthrough neutrino results came from Borexino, a massive, calorimetric liquid scintillator detector installed at the underground Gran Sasso Laboratory. With its unprece- dented radiopurity levels attained in the core of the detection medium, it was, until it took data, the only experiment able to study in real time solar neutrino interactions in the challenging sub-MeV energy region. The recently achieved outstanding rst observation of the CNO ux is thoroughly described in this work. Its other results in the solar neutrino eld are remined, namely the rst real time, spectroscopic measurement of the pp ux, the precise measurement of the 7Be ux, the high signi cance pep ux observation, and the measurement of the 8B neutrino spectrum. Such an impressive series of outputs makes Borexino the only experiment operated so far which was able to perform the full solar neutrino spectroscopy. The physics implications in the realm of neutrino oscillations stemming from the plethora of Borexino outputs is also illustrated.
Показать АннотациюIn the present work we report on the observation of an excess of gamma-ray candidate events in temporal and spatial coincidence with the IceCube high-energy neutrino alert consistent with the origin in the Cygnus Cocoon region. The observations have been performed with Carpet-2, a surface air-shower detector equipped with a large-area muon detector at the Baksan Neutrino Observatory in the Northern Caucasus. As well as we report about the current state of the Carpet- 3 facility, which includes a muon detector with an increased area and an expanded surface array. The main aim of the Carpet-3 facility is the registration of cosmic gamma-rays with energy larger than 100 TeV. Moreover, it gives a possibility to carry out research on the composition of primary cosmic rays around the knee. It is planned that the Carpet-3 EAS array will be operation by the end of 2021.
Показать АннотациюStars are fuelled by the fusion of hydrogen into helium via two processes: the \pp chain" and the \CNO cycle". Neutrinos emitted in the core of the Sun are the only direct probe for the investigation of such processes. The Borexino experiment has performed a complete spectroscopy of the neutrinos from the \pp chain", and has recently reported the rst experimental evidence of neutrinos from the CNO cycle, never observed before, being this process subdominant in the Sun (about 1% of the solar energy). This experimental evidence of the CNO neutrinos was obtained using the highly radiopure large-volume liquid-scintillator detector of Borexino. Advances in the thermal stabilization of the detector over the last ve years enabled us to exploit a method to constrain the rate of Bi-210 contaminating the scintillator, the main background for such a measurement. Since the CNO cycle is dominant in massive starts, this result proves the evidence of the primary mechanism for the stellar conversion of hydrogen into helium in the Universe.
Показать АннотациюWith the experience of successfully developing the 20-inch MCP-PMT (LPMT), the MCP-PMT group in China is now focusing on the R&D of small-sized fast MCP-PMT (FPMT) with time resolution on the order of tens of picoseconds. By now, the single-anode, 22 anodes, 44 anodes and 88 anodes FPMT prototypes have been produced by the cooperation company and evaluated in the PMT Lab in IHEP. The best transit time resolution (TTS) for the 88 anodes FPMT can reach 47 ps for single photoelectron and 16 ps for multi photoelectrons.
Показать АннотациюThe possibility of the validation of the 3+1 neutrino model is considered in the context of the new result of the Neutrino-4 experiment, the direct observation of the oscillation effect at parameter region \(\Delta m_{14}^2=(7.3 \pm 0.13_{st} \pm 1.16_{syst}) \text{eV}^2\) and \(\sin^22\theta_{14} = 0.36 \pm 0.12_{stat} (2.9\sigma)\). The correspondence of the results obtained in the Neutrino-4 experiment with the results of the BEST experiment with a \({}^\text{51}\text{Cr}\) neutrino source is analyzed. Combining the result of the Neutrino-4 experiment and the result of the BEST experiment \(\sin^22\theta_{14} = 0.32 \pm 0.08\) we obtained \(\sin^22\theta_{14} \approx 0.33 \pm 0.07 (4.9\sigma)\). The sterile neutrino parameters from the Neutrino-4 and BEST experiments make it possible to estimate the sterile neutrino mass $m_4 = (2.70 \pm 0.22)\text{eV}$ and the effective mass of the electron neutrino \(m_{4\nu_e} = (0.82 \pm 0.16)\text{eV}\). The matrix of the 3 + 1 neutrino model and the mixing scheme are presented.
Показать АннотациюA brief overview of some topics in flavour physics is carried out, in particular exploring possible links to neutrino mass generation. Following a short discussion of leptonic flavour and CP violation observables (calling for the presence of New Physics), we briefly revisit well-motivated mechanisms of neutrino mass generation, and their implications for the above mentioned leptonic flavoured observables. We finally present some illustrative examples of Standard Model extensions aiming at simultaneously addressing neutrino mass generation as well as easing further tensions (as flavour anomalies or offering viable dark matter candidates).
Показать АннотациюIn this talk I will present the current status of neutrino mixing parameters and masses. Since the discovery of oscillations, neutrino oscillation experiments have reached a very good level in precision. Due to correlations among parameters a global t combining many di erent datasets can give more precise results than a single experiment on its own. I will present the results of the latest global t performed by our group.
Показать АннотациюThe ENUBET experiment is developing a new narrow-band neutrino beam in which the flux and the flavor composition are known at 1% level, and the energy with O(10%) precision. Such a goal is accomplished monitoring the associated charged leptons produced in the decay region of the ENUBET facility: $e^+$ and $\mu^+$ from kaons are measured by a segmented calorimeter instrumenting the walls of the decay tunnel, while muon stations after the hadron dump can monitor muons from pions. We report an update on the status of the project.
Показать АннотациюWe report on the latest measurements of muon neutrino survival and electron neutrino appearance in an accelerator-generated muon neutrino beam of high purity (and the corresponding processes in an anti-neutrino beam), with the Tokai-to-Kamioka (T2K) experiment. The T2K result sets the most sensitive limits on certain oscillation parameters, in particular the CP violating phase, showing an indication of matter-antimatter asymmetry in the leptonic sector, and excluding large parts of the available parameter space at the 3 sigma con dence limit. The analysis improvements feeding into our latest result, as well as future experiment prospects, will also be addressed.
Показать АннотациюIt is necessary to take into account the neutron background in almost all low-background research. In this paper an estimated neutron ux in the underground laboratory DULB-4900 of BNO INR RAS is presented. The estimation is based on results of measurements of radionuclide content in surrounding rock (granite).
Показать АннотациюIn the work arguments are provided in favor of using tritium as an (anti)neutrino source in experiments on research of neutrino electromagnetic properties. It is described the evolution of the tritium (anti)neutrino source design with the intensity of 40 MCi with respect to experiments on defining the neutrino magnetic moment. The physical experiment particulars are discussed with account for physical, chemical and radiational properties of tritium. In continuation of work [1] on the research of neutrino coherent scattering at atoms and nuclei of liquid helium present in the superfluid state, as well as and on the research of neutrino electromagnetic properties, it is proposed using a tritium source with the intensity of 10 MCi. Specifics of such experiments are discussed.
Показать АннотациюThe cosmic silence of the underground Gran Sasso laboratory together with the exceptional radio purity of the liquid scintillator, has allowed Borexino to investigate the radiogenic heating of the Earth's interior and to contribute to various elds of experimental neutrino astronomy. This contribution is aimed to summarize the results obtained by Borexino on geo-neutrinos and on possible extra-terrestrial sources of antineutrinos such as supernovae explosions and solar ares.
Показать АннотациюWe present recent results on neutral fermion pair production by magnetic eld inhomogeneities as external backgrounds. Vacuum instability characteristics are calculated in the framework of QED with x-steps and speci ed to a magnetic step that allows solving the relativistic wave equation pertinent to this problem.
Показать АннотациюThe neutrino propagation and oscillations in various gravitational elds are studied. First, we consider the neutrino scattering o a black hole accounting for the neutrino spin precession. Then, we study the evolution of avor neutrinos in stochastic gravitational waves. The astrophysical applications of the obtained results are considered.
Показать АннотациюWe describe progress applying the Worldline Formalism of quantum eld theory to the fermion propagator dressed by N-photons to study multi-linear Compton scattering processes, explaining how this approach { whose calculational advantages are well-known at multi-loop order { yields compact and manifestly gauge invariant scattering amplitudes.
Показать АннотациюA eld interpretation of General Relativity has been presented for a static eld of black holes and de Sitter's vacuum describing dark energy. The gravitational potential satis es Poisson's equation. Einstein{Hilbert's equations in these cases prove to be super uous.
Показать АннотациюWe compare two different approaches to compute the effects of vacuum polarization associated with a massless scalar field near pointlike source with a zero-range potential in three spatial dimensions. The first one consists in the usage of delta-like sequence of regular potentials, regarding the limit as a model of pointlike interaction. We use the Perturbation theory in the Fourier space. The second approach implies the self-adjoint extension technique. We compute the renormalized vacuum expectation value of the field square $\langle \phi^{\kn 2}(x)\rangle_{\rm ren}$ in non-perturbative sense.
Показать АннотациюI introduce a model to explain the recent anomalies in the muon anomalous magnetic moment and the rare semi-leptonic B meson decays. The Standard Model is extended by a U(1)0 gauge symmetry and a complete fourth family fermions which are vector-like under the gauge symmetry. We found parameter points which can explain the anomalies consistently with the other observables. We then propose an interesting possibility to have signals with four muons or more from vector-like lepton pair production.
Показать АннотациюThe interaction of $\gamma_5$-modified Dirac fields with electromagnetic field is introduced. The possible gauge invariance is studied.
Показать АннотациюThe 2020 announcement by LHCb of a narrow structure $X(6900)$ in the di-$J/\psi$ spectrum---a potential $c\bar c c\bar c$ state---has opened a new era in hadronic spectroscopy. In this talk, we briefly survey theory works preceding this event, examine key features of the observed spectrum, and then discuss how subsequent theory studies (including with the author's own dynamical diquark model) have interpreted these features. We conclude with proposals for experiments capable of distinguishing competing interpretations.
Показать АннотациюWhen neutrinos pass through a medium, they would bear the well known matter effect. In this talk, we will focus on the less discussed matter-dominated case. We find that when neutrinos having extremely high energy or going through extremely dense object, $\nu^{}_{e}$ decoupled due to its intense charged-current interaction with electrons while a two-flavor oscillation are still presented between $\nu^{}_{\mu}$ and $\nu^{}_{\tau}$. This interesting effect may open a ``weak'' eye by observing the distortion of the spectrum of MeV cosmic neutrinos to uncover those hidden compact objects around us.
Показать АннотациюIt is shown that the structure of the mass spectrum of light fermions is naturally explained within the framework of the non-Hermitian theory with a fundamental mass. The ability of leptons to interact with a massless vector field (i.e., to have an electric charge) is associated with the chiral symmetry of their masses. Difficulties in understanding the masses of left-handed neutrinos are associated not so much with their smallness as with their complex connection with energetics.
Показать АннотациюWithin the worldline approach to quantum electrodynamics (QED), a change of the photon's covariant gauge parameter $\xi$ is investigated to analyse the non-perturbative gauge dependence of the configuration space fermion correlation functions, deriving a generalization of the Landau-Kalatnikov-Fradkin transformations (LKFt). These transformations reveal how the non-perturbative gauge dependence of position space amplitudes can be extracted into a multiplicative exponential factor.
Показать АннотациюLight passing through the medium of massive neutral Dirac fermions with magnetic moment might experience change in the index of refraction with respect to vacuum. Possible candidates for a pure medium of massive neutral dirac fermions with magnetic moment are cosmic neutrino background (CNB) and dark matter (DM). In this work, using thermal quantum eld theory and its real-time formalism, we calculate the correction to the photon index of refraction due to the presence of medium of neutral Dirac fermions with CNB-like statistical properties, for which we nd exactly zero e ect.
Показать АннотациюA novel mechanism of baryogenesis that operates through asymmetric capture of baryons and antibaryons by primordial black holes is proposed. It is shown that in maximally broken $C$ and $CP$ symmetries scenario there is a possibility to generate the observed magnitude of baryon asymmetry solely due to asymmetric capture events.
Показать АннотациюWe briefly describe the perturbative derivation of the NSVZ $\beta$-function in ${\cal N}=1$ supersymmetric theories regularized by higher covariant derivatives and of a renormalization prescription under which the NSVZ $\beta$-function is valid in all orders.
Показать АннотациюPhase diagram of two-color quark matter with chiral chemical potential $\mu_5$ has been investigated in the framework of effective model. One can witness a rather rich phase structure, where, for example, $\mu_5$ can play the role of universal catalyzer for all phenomena and exhibit the ability to mimicry all other chemical potentials.
Показать АннотациюThe 20th Lomonosov Conference on Elementary Particle Physics was held online at the Moscow State University (Moscow, Russia) on August 19-25, 2021 under the patronage of academician Victor Sadovnichy, the Rector of the Moscow State University. The 20th Lomonosov Conference was dedicated to the Russian National Year of Science and Technology. The conference was organized by the Faculty of Physics of the Moscow State University in cooperation with the Joint Institute for Nuclear Research (Dubna) and the Institute for Nuclear Research of the Russian Academy of Sciences. A reasonable support in organizing of the event was provided by the Interregional Centre for Advanced Studies and the Bruno Pontecorvo Neutrino and Astrophysics Laboratory (MSU).
Показать Аннотацию