V. A. Polyakov
A5069113215- Particle physics theoretical and experimental studies
- Quantum Chromodynamics and Particle Interactions
- High-Energy Particle Collisions Research
- Dark Matter and Cosmic Phenomena
- Particle Detector Development and Performance
- Nuclear physics research studies
- Neutrino Physics Research
- Computational Physics and Python Applications
- Atomic and Subatomic Physics Research
- Radiation Detection and Scintillator Technologies
- Astrophysics and Cosmic Phenomena
- Particle Accelerators and Free-Electron Lasers
- Crystallography and Radiation Phenomena
- Black Holes and Theoretical Physics
- Particle accelerators and beam dynamics
- Cosmology and Gravitation Theories
- Radiation Therapy and Dosimetry
- Silicone and Siloxane Chemistry
- Algorithms and Data Compression
- Terahertz technology and applications
- Electrochemical Analysis and Applications
- Ferrocene Chemistry and Applications
- Random Matrices and Applications
- Synthesis and properties of polymers
- Geometric and Algebraic Topology
Kurchatov Institute
2015-2024
European Organization for Nuclear Research
2023-2024
Federico Santa María Technical University
2024
Centro Científico Tecnológico de Valparaíso
2024
York University
2023
University of Genoa
2023
Universidad Andrés Bello
2023
Instituto de Física Corpuscular
2023
A. Alikhanyan National Laboratory
2023
University of Aveiro
2021-2023
A new general purpose fixed target facility is proposed at the CERN SPS accelerator which aimed exploring domain of hidden particles and make measurements with tau neutrinos. Hidden are predicted by a large number models beyond Standard Model. The high intensity 400~GeV beam allows probing wide variety containing light long-lived exotic masses below ${\cal O}$(10)~GeV/c$^2$, including very weakly interacting low-energy SUSY states. experimental programme capable being extended in future,...
A search for sub-GeV dark matter production mediated by a new vector boson A^{'}, called photon, is performed the NA64 experiment in missing energy events from 100 GeV electron interactions an active beam dump at CERN SPS. From analysis of data collected years 2016, 2017, and 2018 with 2.84×10^{11} electrons on target no evidence such process has been found. The most stringent constraints A^{'} mixing strength photons parameter space scalar fermionic mass range ≲0.2 are derived, thus...
We report on a direct search for sub-GeV dark photons (${A}^{\ensuremath{'}}$), which might be produced in the reaction ${e}^{\ensuremath{-}}Z\ensuremath{\rightarrow}{e}^{\ensuremath{-}}Z{A}^{\ensuremath{'}}$ via kinetic mixing with by 100 GeV electrons incident an active target NA64 experiment at CERN SPS. The would decay invisibly into matter particles resulting events large missing energy. No evidence such decays was found $2.75\ifmmode\times\else\texttimes\fi{}1{0}^{9}$ target. set new...
A search is performed for a new sub-GeV vector boson (${A}^{\ensuremath{'}}$) mediated production of dark matter ($\ensuremath{\chi}$) in the fixed-target experiment, NA64, at CERN SPS. The ${A}^{\ensuremath{'}}$, called photon, can be generated reaction ${e}^{\ensuremath{-}}Z\ensuremath{\rightarrow}{e}^{\ensuremath{-}}Z{A}^{\ensuremath{'}}$ 100 GeV electrons dumped against an active target followed by its prompt invisible decay...
We report the first results on a direct search for new 16.7 MeV boson (X) which could explain anomalous excess of e^{+}e^{-} pairs observed in excited ^{8}Be^{*} nucleus decays. Because its coupling to electrons, X be produced bremsstrahlung reaction e^{-}Z→e^{-}ZX by 100 GeV e^{-} beam incident an active target NA64 experiment at CERN Super Proton Synchrotron and through subsequent decay into pair. With 5.4×10^{10} electrons target, no evidence such decays was found, allowing us set limits...
The improved results on a direct search for new X(16.7 MeV) boson which could explain the anomalous excess of $e^+e^-$ pairs observed in excited 8Be nucleus decays ("Berillium anomaly") are reported. Due to its coupling electrons, X be produced bremsstrahlung reaction e-Z -> e-ZX by high-energy beam electrons incident active target NA64 experiment at CERN SPS and through subsequent decay into pair. No evidence such was found from combined analysis data samples with total statistics...
We carried out a model-independent search for light scalar ($s$) and pseudoscalar axionlike ($a$) particles that couple to two photons by using the high-energy CERN SPS H4 electron beam. The new particles, if they exist, could be produced through Primakoff effect in interactions of hard bremsstrahlung generated 100 GeV electrons NA64 active dump with virtual provided nuclei dump. $a(s)$ would penetrate downstream HCAL module, serving as shield, observed either their...
Thermal dark matter models with particle χ masses below the electroweak scale can provide an explanation for observed relic density. This would imply existence of a new feeble interaction between and ordinary matter. We report on search sub-GeV production through mediated by vector boson, called photon A^{'}, in collisions 100 GeV electrons active target NA64 experiment at CERN SPS. With 9.37×10^{11} collected during 2016-2022 runs probes first time well-motivated region parameter space...
We report the first search for dark sectors performed at NA64 experiment employing a high energy muon beam and missing energy-momentum technique. Muons from M2 beamline CERN Super Proton Synchrotron with momentum of <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:mn>160</a:mn><a:mtext> </a:mtext><a:mtext> </a:mtext><a:mi>GeV</a:mi><a:mo>/</a:mo><a:mi>c</a:mi></a:mrow></a:math> are directed to an active target. The signal signature consists single scattered...
The current most stringent constraints for the existence of sub-GeV dark matter coupling to Standard Model via a massive vector boson ${A}^{\ensuremath{'}}$ were set by NA64 experiment mass region ${m}_{{A}^{\ensuremath{'}}}\ensuremath{\lesssim}250\text{ }\text{ }\mathrm{MeV}$, analyzing data from interaction $2.84\ifmmode\times\else\texttimes\fi{}{10}^{11}$ 100-GeV electrons with an active thick target and searching missing-energy events. In this work, including production secondary...
A search for a new Z^{'} gauge boson associated with (un)broken B-L symmetry in the keV-GeV mass range is carried out first time using missing-energy technique NA64 experiment at CERN SPS. From analysis of data 3.22×10^{11} electrons on target collected during 2016-2021 runs, no signal events were found. This allows us to derive constraints Z^{'}-e coupling strength, which, 0.3≲m_{Z^{'}}≲100 MeV, are more stringent compared those obtained from neutrino-electron scattering data.
A bstract The inclusion of an additional U(1) gauge L μ − τ symmetry would release the tension between measured and predicted value anomalous muon magnetic moment: this paradigm assumes existence a new, light Z ′ vector boson, with dominant coupling to leptons interacting electrons via loop mechanism. model can also explain Dark Matter relic abundance, by assuming that boson acts as “portal” new Sector particles in Nature, not charged under known interactions. In work we present results...
Thermal light dark matter (LDM) with particle masses in the 1 MeV - GeV range could successfully explain observed abundance as a relic from primordial Universe. In this picture, new feeble interaction acts "portal" between Standard Model and LDM particles, allowing for exploration of paradigm at accelerator experiments. last years, "missing energy" experiment NA64e CERN SPS (Super Proton Synchrotron) has set world-leading constraints vector-mediated parameter space, by exploiting 100...
We performed a search for new generic $X$ boson, which could be scalar ($S$), pseudoscalar ($P$), vector ($V$), or an axial ($A$) particle produced in the 100 GeV electron scattering off nuclei, ${e}^{\ensuremath{-}}Z\ensuremath{\rightarrow}{e}^{\ensuremath{-}}ZX$, followed by its invisible decay NA64 experiment at CERN. No evidence such process was found full dataset of $2.84\ifmmode\times\else\texttimes\fi{}{10}^{11}$ electrons on target. place bounds $S$, $P$, $V$, $A$ coupling strengths...
Several models of dark matter suggest the existence sectors consisting SU(3)_C x SU(2)_L U(1)_Y singlet fields. These particles do not interact with ordinary directly but could couple to it via gravity. In addition gravity, there might be another very weak interaction between and mediated by U'(1) gauge bosons A' (dark photons) mixing our photons. a class corresponding light have $γ$-A' coupling strength laying in experimentally accessible theoretically interesting region. If such mediators...
The extension of Standard Model made by inclusion additional $U(1)$ gauge ${L}_{\ensuremath{\mu}}\ensuremath{-}{L}_{\ensuremath{\tau}}$ symmetry can explain the difference between measured and predicted value muon magnetic moment solve tension in $B$ meson decays. This model predicts existence a new, light ${Z}^{\ensuremath{'}}$ vector boson, predominantly coupled to second third generation leptons, whose interaction with electrons is due loop mechanism involving muons taus. In this work, we...
We present the results of a missing-energy search for light dark matter which has new interaction with ordinary transmitted by vector boson, called photon <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:msup><a:mi>A</a:mi><a:mo>′</a:mo></a:msup></a:math>. For first time, this is performed positron beam using significantly enhanced production <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:msup><c:mi>A</c:mi><c:mo>′</c:mo></c:msup></c:math> in...
We report the results of a search for light pseudoscalar particle $a$ that couples to electrons and decays ${e}^{+}{e}^{\ensuremath{-}}$ performed using high-energy CERN SPS H4 electron beam. If such exists, it could explain ATOMKI anomaly (an excess pairs in nuclear transitions $^{8}\mathrm{Be}$ $^{4}\mathrm{He}$ nuclei at invariant mass $\ensuremath{\simeq}17\text{ }\text{ }\mathrm{MeV}$ observed by experiment 5 MV Van de Graaff accelerator ATOMKI, Hungary). used NA64 data collected...
Abstract We report the results of a search for new vector boson ( $$ A'$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mi>A</mml:mi> <mml:mo>′</mml:mo> </mml:msup> </mml:math> ) decaying into two dark matter particles $$\chi _1 \chi _2$$ <mml:mrow> <mml:msub> <mml:mi>χ</mml:mi> <mml:mn>1</mml:mn> </mml:msub> <mml:mn>2</mml:mn> </mml:mrow> different mass. The heavier particle subsequently decays to _1$$ and an off-shell Dark Photon A'^* \rightarrow e^+e^-$$...
The decay K−→π0μ−ν has been studied using in-flight decays detected with the "STRA+" spectrometer. About 540K events were collected for analysis. λ+ and λ0 slope parameters of form-factors f+(t), f0(t) have measured: λ+=0.0277±0.0013(stat)±0.0009(syst), λ0=0.0183±0.0011(stat)±0.0006(syst), dλ0/dλ+=−0.348. limits on possible tensor scalar couplings derived: fT/f+(0)=−0.0007±0.0071, fS/f+(0)=0.0017±0.0014. No visible non-linearity in observed.
In high energy experiments such as active beam dump searches for rare decays and missing events, the purity is a crucial parameter. this paper we present technique to reject heavy charged particle contamination in 100 GeV electron of H4 line at CERN SPS. The method based on detection with BGO scintillators synchrotron radiation emitted by electrons passing through bending dipole magnet. A π− used test NA64 experiment resulting suppression factor 10−5 while efficiency ∼95%. spectra rejection...