Examinando por Autor "Andreev, Yu. M."
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Ítem First constraints on the Lμ− Lτ explanation of the muon g-2 anomaly from NA64-e at CERN(Springer Science and Business Media Deutschland GmbH, 2024-07) Andreev, Yu. M.; Antonov A.; Banerjee D.; Banto Oberhauser B.; Bernhard J.; Bisio P.; Celentano A.; Charitonidis N.; Cooke D.; Crivelli P.; Depero E.; Dermenev A.V.; Donskov S.V.; Dusaev R.R.; Enik T.; Frolov V.N.; Gardikiotis A.; Gertsenberger S.V.; Girod S.; Gninenko S.N.; Hösgen M.; Kachanov V.A.; Kambar Y.; Karneyeu A.E.; Kasianova E.A.; Kekelidze G.; Ketzer B.; Kirpichnikov D.V.; Kirsanov M.M.; Kolosov V.N.; Kramarenko V.A.; Kravchuk L.V.; Krasnikov N.V.; Kuleshov S.V.; Lyubovitskij V.E.; Lysan V.; Marini A.; Marsicano L.; Matveev V.A.; Mena Fredes R.; Mena Yanssen R.; Molina Bueno L.; Mongillo M.; Peshekhonov D.V.; Polyakov V.A.; Radics B.; Salamatin K.; Samoylenko V.D.; Sieber H.; Shchukin D.; Soto O.; Tikhomirov V.O.; Tlisova I.; Toropin A.N.; Tuzi M.; Ulloa P.; Volkov P.V.; Volkov, V. Yu.; Voronchikhin I.V.; Zamora-Saá J.The inclusion of an additional U(1) gauge Lμ − Lτ symmetry would release the tension between the measured and the predicted value of the anomalous muon magnetic moment: this paradigm assumes the existence of a new, light Z′ vector boson, with dominant coupling to μ and τ leptons and interacting with electrons via a loop mechanism. The Lμ − Lτ model can also explain the Dark Matter relic abundance, by assuming that the Z′ boson acts as a “portal” to a new Dark Sector of particles in Nature, not charged under known interactions. In this work we present the results of the Z′ search performed by the NA64-e experiment at CERN SPS, that collected ~ 9 × 1011 100 GeV electrons impinging on an active thick target. Despite the suppressed Z′ production yield with an electron beam, NA64-e provides the first accelerator-based results excluding the g − 2 preferred band of the Z′ parameter space in the 1 keVÍtem Improved exclusion limit for light dark matter from e+e- annihilation in NA64(American Physical Society, 2021-11-01) Andreev, Yu. M.; Banerjee D.; Bernhard J.; Bondì M.; Burtsev V.E.; Celentano A.; Charitonidis N.; Chumakov A.G.; Cooke D.; Crivelli P.; Depero E.; Dermenev A.V.; Donskov S.V.; Dusaev R.R.; Enik T.; Feshchenko A.; Frolov V.N.; Gardikiotis A.; Gerassimov S.G.; Gninenko S.N.; Hösgen M.; Jeckel M.; Kachanov V.A.; Karneyeu A.E.; Kekelidze G.; Ketzer B.; Kirpichnikov D.V.; Kirsanov M.M.; Kolosov V.N.; Konorov I.V.; Kovalenko S.G.; Kramarenko V.A.; Kravchuk L.V.; Krasnikov N.V.; Kuleshov S.V.; Lyubovitskij V.E.; Lysan V.; Marsicano L.; Matveev V.A.; Mikhailov, Yu. V.; Molina Bueno L.; Peshekhonov D.V.; Polyakov V.A.; Radics B.; Rojas R.; Rubbia A.; Samoylenko V.D.; Sieber H.; Shchukin D.; Tikhomirov V.O.; Tlisova I.; Toropin A.N.; Trifonov, A. Yu.; Ulloa P.; Vasilishin B.I.; Vasquez Arenas G.; Volkov P.V.; Volkov, V. Yu.The current most stringent constraints for the existence of sub-GeV dark matter coupling to Standard Model via a massive vector boson A′ were set by the NA64 experiment for the mass region mA′≲250 MeV, by analyzing data from the interaction of 2.84×1011 100-GeV electrons with an active thick target and searching for missing-energy events. In this work, by including A′ production via secondary positron annihilation with atomic electrons, we extend these limits in the 200-300 MeV region by almost an order of magnitude, touching for the first time the dark matter relic density constrained parameter combinations. Our new results demonstrate the power of the resonant annihilation process in missing energy dark-matter searches, paving the road to future dedicated e+ beam efforts.Ítem Measurement of the intrinsic hadronic contamination in the NA64−e high-purity e+/e− beam at CERN(Elsevier B.V., 2023-12) Andreev, Yu. M.; Banerjee, D.; Banto Oberhauser, B.; Bernhard, J.; Bisio, P.; Bondí, M.; Celentano, A.; Charitonidis, N.; Chumakov, A. G.; Cooke, D.; Crivelli, P.; Depero, E.; Dermenev, A. V.; Donskov, S. V.; Dusaev, R. R.; Enik, T.; Frolov, V. N.; Gardikiotis, A.; Gerassimov, S. G.; Gninenko, S. N.; Hösgen, M.; Jeckel, M.; Kachanov, V. A.; Kambar, Y.; Karneyeu, A. E.; Kekelidze, G.; Ketzer, B.; Kirpichnikov, D. V.; Kirsanov, M. M.; Kolosov, V. N.; Konorov, I. V.; Gertsenberger, S. V.; Kasianova, E. A.; Kovalenko, S. G.; Kramarenko, V. A.; Kravchuk, L. V.; Krasnikov, N. V.; Kuleshov, S. V.; Lyubovitskij, V. E.; Lysan, V.; Marini, A.; Marsicano, L.; Matveev, V. A.; Mikhailov, Yu. V.; Molina Bueno, L.; Mongillo, M.; Peshekhonov, D. V.; Polyakov, V. A.; Radics, B.; Rojas, R.; Salamatin, K.; Samoylenko, V. D.; Sieber, H.; Shchukin, D.; Soto, O.; Tikhomirov, V. O.; Tlisova, I.; Toropin, A. N.; Trifonov, A. Yu.; Tuzi, M.; Ulloa, P.; Vasilishin, B. I.; Vasquez Arenas, G.; Volkov, P. V.; Volkov, V. Yu.; Voronchikhin, I. V.; Zamora-Saá, J.; Zhevlakov, A. S.We present the measurement of the intrinsic hadronic contamination at the CERN SPS H4 beamline configured to transport electrons and positrons at 100 GeV/c. The analysis, performed using data collected by the NA64-e experiment in 2022, is based on calorimetric measurements, exploiting the different interaction mechanisms of electrons and hadrons in the NA64 detector. We determined the contamination by comparing the results obtained using the nominal electron/positron beamline configuration with those from a dedicated setup, in which only hadrons impinged on the detector. We also obtained an estimate of the relative protons, anti-protons and pions yield by exploiting the different absorption probabilities of these particles in matter. We cross-checked our results with a dedicated Monte Carlo simulation for the hadron production at the primary T2 target, finding a good agreement with the experimental measurements.Ítem Probing light dark matter with positron beams at NA64(American Physical Society, 2024-02-01) Andreev, Yu. M.; Antonov A.; Banerjee D.; Banto Oberhauser B.; Bernhard J.; Bisio P.; Bondí M.; Celentano A.; Charitonidis N.; Cooke D.; Crivelli P.; Depero E.; Dermenev A.V.; Donskov S.V.; Dusaev R.R.; Enik T.; Frolov V.N.; Gardikiotis A.; Gninenko S.N.; Hösgen M.; Kachanov V.A.; Kambar Y.; Karneyeu A.E.; Kekelidze G.; Ketzer B.; Kirpichnikov D.V.; Kirsanov M.M.; Gertsenberger S.V.; Girod S.; Kasianova E.A.; Kramarenko V.A.; Kravchuk L.V.; Krasnikov N.V.; Kuleshov S.V.; Lyubovitskij V.E.; Lysan V.; Marini A.; Marsicano L.; Matveev V.A.; Mena Fredes R.; Mena Yanssen R.; Molina Bueno L.; Mongillo M.; Peshekhonov D.V.; Polyakov V.A.; Radics B.; Salamatin K.; Samoylenko V.D.; Sieber H.; Shchukin D.; Soto O.; Tikhomirov V.O.; Tlisova I.; Toropin A.N.; Tuzi M.; Ulloa P.; Volkov P.V.; Volkov, V. Yu.; Voronchikhin I.V.We present the results of a missing-energy search for light dark matter which has a new interaction with ordinary matter transmitted by a vector boson, called dark photon A′. For the first time, this search is performed with a positron beam by using the significantly enhanced production of A′ in the resonant annihilation of positrons with atomic electrons of the target nuclei, followed by the invisible decay of A′ into dark matter. No events were found in the signal region with (10.1±0.1)×109 positrons on target with 100 GeV energy. This allowed us to set new exclusion limits that, relative to the collected statistics, prove the power of this experimental technique. This measurement is a crucial first step toward a future exploration program with positron beams, whose estimated sensitivity is here presented.Ítem Search for a light Z′ in the Lμ-Lτ scenario with the NA64-e experiment at CERN(American Physical Society, 2022-08) Andreev, Yu. M.; Banerjee, D.; Banto Oberhauser, B.; Bernhard, J.; Bisio, P.; Bondí, M.; Burtsev, V.E.; Celentano, A.; Charitonidis, N.; Chumakov, A.G.; Cooke, D.; Crivelli, P.; Depero, E.; Dermenev, A.V.; Donskov, S.V.; Dusaev, R.R.; Enik, T.; Frolov, V.N.; Gardikiotis, A.; Gerassimov, S.G.; Gninenko, S.N.; Hösgen, M.; Jeckel, M.; Kachanov, V.A.; Karneyeu, A.E.; Kekelidze, G.; Ketzer, B.; Kirpichnikov, D.V.; Kirsanov, M.M.; Kolosov, V.N.; Konorov, I.V.; Kovalenko, S.G.; Kramarenko, V.A.; Kravchuk, L.V.; Krasnikov, N.V.; Kuleshov, S.V.; Lyubovitskij, V.E.; Lysan, V.; Marsicano, L.; Matveev, V.A.; Mikhailov, Yu. V.; Molina Bueno, L.; Peshekhonov, D.V.; Polyakov, V.A.; Radics, B.; Rojas, R.; Rubbia, A.; Salamatin, K.M.; Samoylenko, V.D.; Sieber, H.; Shchukin, D.; Tikhomirov, V.O.; Tlisova, I.; Toropin, A.N.; Trifonov, A. Yu.; Ulloa, P.; Vasilishin, B.I.; Vasquez Arenas, G.; Volkov, P.V.; Volkov, V. Yu.; Voronchikhin, I.The extension of Standard Model made by inclusion of additional U(1) gauge Lμ-Lτ symmetry can explain the difference between the measured and the predicted value of the muon magnetic moment and solve the tension in B meson decays. This model predicts the existence of a new, light Z′ vector boson, predominantly coupled to second and third generation leptons, whose interaction with electrons is due to a loop mechanism involving muons and taus. In this work, we present a rigorous evaluation of the upper limits in the Z′ parameter space, obtained from the analysis of the data collected by the NA64-e experiment at CERN SPS, that performed a search for light dark matter with 2.84×1011 electrons impinging with 100 GeV on an active thick target. The resulting limits touch the muon g-2 preferred band for values of the Z′ mass of order of 1 MeV, while the sensitivity projections for the future high-statistics NA64-e runs demonstrate the power of the electrons/positron beam approach in this theoretical scenario. © 2022 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the "https://creativecommons.org/licenses/by/4.0/"Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP3.Ítem Search for a New B-L Z′ Gauge Boson with the NA64 Experiment at CERN(American Physical Society, 2022-10-14) Andreev, Yu. M.; Banerjee, D.; Oberhauser B., Banto; Bernhard, J.; Bisio, P.; Burtsev, V.E.; Celentano, A.; Charitonidis, N.; Chumakov, A.G.; Cooke, D.; Crivelli, P.; Depero, E.; Dermenev, A.V.; Donskov, S.V.; Dusaev, R.R.; Enik, T.; Frolov, V.N.; Gardikiotis, A.; Gerassimov, S.G.; Gninenko, S.N.; Hösgen, M.; Jeckel, M.; Kachanov, V.A.; Karneyeu, A.E.; Kekelidze, G.; Ketzer, B.; Kirpichnikov, D.V.; Kirsanov, M.M.; Kolosov, V.N.; Kovalenko, S.G.; Kramarenko, V.A.; Kravchuk, L.V.; Krasnikov, N.V.; Kuleshov, S.V.; Lyubovitskij, V.E.; Lysan, V.; Marsicano, L.; Matveev, V.A.; Mikhailov, Yu. V.; Molina Bueno, L.; Peshekhonov, D.V.; Polyakov, V.A.; Radics, B.; Rubbia, A.; Samalantin, K.M.; Samoylenko, V.D.; Sieber, H.; Shchukin, D.; Soto, O.; Tikhomirov, V.O.; Tlisova, I.V.; Toropin, A.N.; Vasilishin, B.I.; Volkov, P.V.; Volkov, V. Yu.; Voronchikhin, I.; Zamora Saá, J.A search for a new Z′ gauge boson associated with (un)broken B-L symmetry in the keV-GeV mass range is carried out for the first time using the missing-energy technique in the NA64 experiment at the CERN SPS. From the analysis of the data with 3.22×1011 electrons on target collected during 2016-2021 runs, no signal events were found. This allows us to derive new constraints on the Z′-e coupling strength, which, for the mass range 0.3mZ′ 100 MeV, are more stringent compared to those obtained from the neutrino-electron scattering data. © 2022 authors. Published by the American Physical Society.Ítem Search for Light Dark Matter with NA64 at CERN(American Physical Society, 2023-10-20) Andreev, Yu. M.; Banerjee D.; Banto Oberhauser B.; Bernhard J.; Bisio P.; Celentano A.; Charitonidis N.; Chumakov A.G.; Cooke D.; Crivelli P.; Depero E.; Dermenev A.V.; Donskov S.V.; Dusaev R.R. .; Enik T.; Frolov V.N.; Galleguillos Silva R.B.; Gardikiotis A.; Gertsenberger S.V.; Girod S.; Gninenko S.N.; Hösgen M.; Kachanov V.A.; Kambar Y.; Karneyeu A.E.; Kasianova E.A.; Kekelidze G.D.; Ketzer B.; Kirpichnikov D.V.; Kirsanov M.M.; Kolosov V.N.; Kramarenko V.A.; Kravchuk L.V.; Krasnikov N.V.; Kuleshov S.V.; Lyubovitskij V.E.; Lysan V.; Marini A.; Marsicano L.; Matveev V.A.; Mena Fredes R.; Mena Yanssen R.G.; Molina Bueno L.; Mongillo M.; Peshekhonov D.V.; Polyakov V.A.; Radics B.; Salamatin K.M.; Samoylenko V.D.; Sieber H.; Shchukin D.A.; Soto O.; Tikhomirov V.O.; Tlisova I.V.; Toropin A.N.; Tuzi M.; Vasilishin B.I.; Volkov P.V.; Volkov, V. Yu.; Voronchikhin I.V.; Zamora-Saá J.; Zhevlakov A.S.Thermal dark matter models with particle χ masses below the electroweak scale can provide an explanation for the observed relic dark matter density. This would imply the existence of a new feeble interaction between the dark and ordinary matter. We report on a new search for the sub-GeV χ production through the interaction mediated by a new vector boson, called the dark photon A′, in collisions of 100 GeV electrons with the active target of the NA64 experiment at the CERN SPS. With 9.37×1011 electrons on target collected during 2016-2022 runs NA64 probes for the first time the well-motivated region of parameter space of benchmark thermal scalar and fermionic dark matter models. No evidence for dark matter production has been found. This allows us to set the most sensitive limits on the A′ couplings to photons for masses mA′≲0.35 GeV, and to exclude scalar and Majorana dark matter with the χ-A′ coupling αD≤0.1 for masses 0.001≲mχ≲0.1 GeV and 3mχ≤mA′.Ítem Search for pseudoscalar bosons decaying into e+e- pairs in the NA64 experiment at the CERN SPS(American Physical Society, 2021-12-01) Andreev, Yu. M.; Banerjee, D.; Bernhard, J.; Burtsev, V. E.; Charitonidis, N.; Chumakov, A. G.; Cooke, D.; Crivelli, P.; Depero, E.; Dermenev, A. V.; Donskov, S. V.; Dusaev, R. R.; Enik, T.; Feshchenko, A.; Frolov, V. N.; Gardikiotis, A.; Gerassimov, S. G.; Gninenko, S. N.; Hösgen, M.; Jeckel, M.; Kachanov, V. A.; Karneyeu, A. E.; Kekelidze, G.; Ketzer, B.; Kirpichnikov, D. V.; Kirsanov, M. M.; Kolosov, V. N.; Konorov, I. V.; Kovalenko, S. G.; Kramarenko, V. A.; Kravchuk, L. V.; Krasnikov, N. V.; Kuleshov, S. V.; Lyubovitskij, V. E.; Lysan, V.; Matveev, V. A.; Mikhailov, Yu. V.; Molina Bueno, L.; Peshekhonov, D. V.; Polyakov, V. A.; Radics, B.; Rojas, R.; Rubbia, A.; Samoylenko, V. D.; Sieber, H.; Shchukin, D.; Tikhomirov, V. O.; Tlisova, I.; Toropin, A. N.; Trifonov, A. Yu.; Vasilishin, B. I.; Vasquez Arenas, G.; Volkov, P. V.; Volkov, V. Yu.; Ulloa, P.We report the results of a search for a light pseudoscalar particle a that couples to electrons and decays to e+e- performed using the high-energy CERN SPS H4 electron beam. If such light pseudoscalar exists, it could explain the ATOMKI anomaly (an excess of e+e- pairs in the nuclear transitions of Be8 and He4 nuclei at the invariant mass ≃17 MeV observed by the experiment at the 5 MV Van de Graaff accelerator at ATOMKI, Hungary). We used the NA64 data collected in the "visible mode"configuration with a total statistics corresponding to 8.4×1010 electrons on target (EOT) in 2017 and 2018. In order to increase sensitivity to small coupling parameter ϵ we also used the data collected in 2016-2018 in the "invisible mode"configuration of NA64 with a total statistics corresponding to 2.84×1011 EOT. The background and efficiency estimates for these two configurations were retained from our previous analyses searching for light vector bosons and axionlike particles (ALP) (the latter were assumed to couple predominantly to γ). In this work we recalculate the signal yields, which are different due to different cross section and lifetime of a pseudoscalar particle a, and perform a new statistical analysis. As a result, the region of the two dimensional parameter space ma-ϵ in the mass range from 1 to 17.1 MeV is excluded. At the mass of the central value of the ATOMKI anomaly (the first result obtained on the beryllium nucleus, 16.7 MeV) the values of ϵ in the range 2.1×10-4<ϵ<3.2×10-4 are excluded.