V. O. Tikhomirov
A5101423920- Particle physics theoretical and experimental studies
- High-Energy Particle Collisions Research
- Particle Detector Development and Performance
- Quantum Chromodynamics and Particle Interactions
- Dark Matter and Cosmic Phenomena
- Computational Physics and Python Applications
- Cosmology and Gravitation Theories
- Neutrino Physics Research
- Radiation Detection and Scintillator Technologies
- Distributed and Parallel Computing Systems
- Astrophysics and Cosmic Phenomena
- Black Holes and Theoretical Physics
- Medical Imaging Techniques and Applications
- Atomic and Subatomic Physics Research
- Particle Accelerators and Free-Electron Lasers
- Superconducting Materials and Applications
- Nuclear physics research studies
- Advanced Data Storage Technologies
- Nuclear reactor physics and engineering
- advanced mathematical theories
- Atomic and Molecular Physics
- Muon and positron interactions and applications
- CCD and CMOS Imaging Sensors
- Radiation Therapy and Dosimetry
- Big Data Technologies and Applications
European Organization for Nuclear Research
2010-2025
P.N. Lebedev Physical Institute of the Russian Academy of Sciences
2015-2024
Brandeis University
2023-2024
Institute of High Energy Physics
2024
A. Alikhanyan National Laboratory
2024
Atlas Scientific (United States)
2024
Moscow Engineering Physics Institute
2014-2023
The University of Adelaide
2014-2023
Universidad Andrés Bello
2023
Instituto de Física Corpuscular
2023
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...
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$$ and an off-shell Dark Photon A'^* \rightarrow e^+e^-$$...
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...
A search for dark sectors is performed using the unique M2 beam line at CERN Super Proton Synchrotron. New particles (<a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mi>X</a:mi></a:math>) could be produced in bremsstrahlung-like reaction of high-energy 160 GeV positively charged muons impinging on an active target, <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mi>μ</c:mi><c:mi>N</c:mi><c:mo...
Abstract Recently, the ATOMKI experiment has reported new evidence for excess of $$e^+e^-$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msup> <mml:mi>e</mml:mi> <mml:mo>+</mml:mo> </mml:msup> <mml:mo>-</mml:mo> </mml:mrow> </mml:math> events with a mass $$\sim $$ <mml:mo>∼</mml:mo> 17 MeV in nuclear transitions $$^4$$ <mml:mrow/> <mml:mn>4</mml:mn> He, that they previously observed measurements $$^8$$ <mml:mn>8</mml:mn> Be. These observations could be explained...
We present the measurement of intrinsic hadronic contamination at CERN SPS H4 beamline configured to transport electrons and positrons 100 GeV/c. The analysis, performed using data collected by NA64-e experiment in 2022, is based on calorimetric measurements, exploiting different interaction mechanisms hadrons NA64 detector. determined comparing results obtained nominal electron/positron configuration with those from a dedicated setup, which only impinged also an estimate relative protons,...