E. A. Kozyrev
A5021362368- 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
- Atomic and Subatomic Physics Research
- Particle Accelerators and Free-Electron Lasers
- Stochastic processes and statistical mechanics
- Cosmology and Gravitation Theories
- Neutrino Physics Research
- Computational Physics and Python Applications
Budker Institute of Nuclear Physics
2018-2022
Siberian Branch of the Russian Academy of Sciences
2020-2022
Novosibirsk State University
2020-2022
Istituto Nazionale di Fisica Nucleare, Sezione di Catania
2018
A bstract The three precision measurements of the cross section σ ( e + − → π γ(γ)) using initial state radiation by KLOE collaboration provide an important input for prediction hadronic contribution to anomalous magnetic moment muon. These are correlated both statistical and systematic uncertainties and, therefore, simultaneous use these requires covariance matrices that fully describe correlations. We present construction them determine a combined measurement γ(γ)). find, from this...
An angular analysis of the decay ${\overline{B} \rightarrow D^\ast \ell^- \overline{\nu}_\ell}$, $\ell\in\{e,\mu\}$, is reported using full $e^+e^-$ collision data set collected by \babar experiment at $\Upsilon(4S)$ resonance. One $B$ meson from ${\Upsilon(4S)\to B\overline{B}}$ fully reconstructed in a hadronic mode, which constrains kinematics and provides determination neutrino momentum vector. The semileptonic described di-lepton mass squared, $q^2$, three angles. first unbinned fit to...
We searched for the $μ^+μ^-$ decay of a light vector gauge boson, also known as dark photon, in $e^+ e^- \to μ^+ μ^- γ_{\rm ISR}$ process by means Initial State Radiation (ISR) method. used 1.93~fb$^{-1}$ data collected KLOE experiment at DA$Φ$NE $ϕ$-factory. No structures have been observed over irreducible $μ^+ μ^-$ background. A 90\% CL limit on ratio $\varepsilon^2=α^{\prime}/α$ between coupling constant and fine structure $ 3\times 10^{-6}-2\times 10^{-7}$ has set photon mass region 519...
A study of the two-body decays B^{±}→X_{cc[over ¯]}K^{±}, where X_{cc[over ¯]} refers to one charmonium state, is reported by BABAR Collaboration using a data sample 424 fb^{-1}. The absolute determination branching fractions for these are significantly improved compared previous measurements. Evidence found decay B^{+}→X(3872)K^{+} at 3σ level. fraction B[B^{+}→X(3872)K^{+}]=[2.1±0.6(stat)±0.3(syst)]×10^{-4} measured first time. It follows that B[X(3872)→J/ψπ^{+}π^{-}]=(4.1±1.3)%,...
We study the processes $\gamma \gamma \to \eta_c \eta' K^+ K^-$, $\eta' \pi^+ \pi^-$, and $\eta \pi^-$ using a data sample of 519 $fb^{-1}$ recorded with BaBar detector operating at SLAC PEP-II asymmetric-energy $e^+e^-$ collider center-of-mass energies near $\Upsilon(nS)$ ($n = 2,3,4$) resonances. This is first observation decay $\eta_c K^-$ we measure branching fraction $\Gamma(\eta_c K^-)/(\Gamma(\eta_c \pi^-)=0.644\pm 0.039_{\rm stat}\pm 0.032_{\rm sys}$. Significant interference...
A dedicated measurement of additional radiation in e+e−→μ+μ−γ and e+e−→π+π−γ initial-state-radiation events is presented using the full BABAR data sample. For first time results are at next-to- next-to-next-to-leading order, with one two photons, respectively, for from initial final states. Comparison predictions phokhara afkqed Monte Carlo generators performed, revealing discrepancies one-photon rates angular distributions former. This disagreement has a negligible effect on e+e−→π+π−(γ)...
Many scenarios of physics beyond the Standard Model predict existence new gauge singlets, which might be substantially lighter than weak scale. The experimental constraints on additional scalars with masses in MeV to GeV range could significantly weakened if they interact predominantly leptons rather quarks. At an $e^+e^-$ collider, such a leptophilic scalar ($\phi_L$) would produced through radiation from $\tau$ lepton. We report herein search for $e^+e^- \to \tau^+\tau^- \phi_L$, $\phi_L...
Using the initial-state radiation method, ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{K}_{S}{K}_{L}$ cross section from 1.98 to 2.54 GeV is measured in a data sample of $469\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ collected with BABAR detector. The results are used conjunction previous for ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{K}^{+}{K}^{\ensuremath{-}}$,...
The process ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{0}\ensuremath{\gamma}$ is studied at a center-of-mass energy near the $\mathrm{\ensuremath{\Upsilon}}(4S)$ resonance using data sample of $469\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ collected with BABAR detector PEP-II collider. We have performed precise measurement...
A bstract Using 1.63 fb −1 of integrated luminosity collected by the KLOE experiment about 7 × 10 4 K S → π ± e ∓ ν decays have been reconstructed. The measured value charge asymmetry for this decay is = (−4.9 5.7 stat 2.6 syst ) −3 , which almost twice more precise than previous result. combination these two measurements gives (−3.8 5.0 and, together with L semileptonic decay, provides significant tests CPT symmetry. obtained results are in agreement invariance.
This article presents a model-independent search for an additional, mostly sterile, heavy neutral lepton (HNL), that is capable of mixing with the Standard Model $\ensuremath{\tau}$ neutrino strength $|{U}_{\ensuremath{\tau}4}{|}^{2}$, corresponding to absolute square extended Pontecorvo-Maki-Nakagawa-Sakata matrix element. Data from BABAR experiment, total integrated luminosity $424\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$, are analyzed using kinematic approach makes no assumptions...
We study the processes ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{K}^{+}{K}^{\ensuremath{-}}{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0}\ensuremath{\gamma}$, ${K}_{S}^{0}{K}^{\ifmmode\pm\else\textpm\fi{}}{\ensuremath{\pi}}^{\ensuremath{\mp}}{\ensuremath{\pi}}^{0}{\ensuremath{\pi}}^{0}\ensuremath{\gamma}$, and...
A new mechanism has been proposed to simultaneously explain the presence of dark matter and matter-antimatter asymmetry in universe. This scenario predicts exotic $B$ meson decays into a baryon sector anti-baryon ($\psi_D$) with branching fractions accessible at factories. We present search for $B \rightarrow \Lambda \psi_D$ using data collected by $BABAR$ experiment SLAC. reaction is identified fully reconstructing accompanying requiring single $\Lambda$ remaining particles. No significant...
The three precision measurements of the cross section $σ\big(e^+e^-\rightarrowπ^+π^-γ(γ)\big)$ using initial state radiation by KLOE collaboration provide an important input for prediction hadronic contribution to anomalous magnetic moment muon. These are correlated both statistical and systematic uncertainties and, therefore, simultaneous use these requires covariance matrices that fully describe correlations. We present construction them determine a combined measurement...
A new dark sector antibaryon, denoted ψD, could be produced in decays of B mesons. This Letter presents a search for B+→ψD+p (and the charge conjugate) e+e− annihilations at 10.58 GeV, using data collected BABAR experiment. Data corresponding to an integrated luminosity 398 fb−1 are analyzed. No evidence signal is observed. Branching fraction upper limits range from 10−7–10−5 obtained 90% confidence level masses 1.0<mψD<4.3 GeV/c2. The result also reinterpreted provide first on...
Collider searches for dark sectors, new particles interacting only feebly with ordinary matter, have largely focused on identifying signatures of mediators, leaving much sector structures unexplored. In particular, the existence matter bound states (darkonia) remains to be investigated. This possibility could arise in a simple model which photon (A^{'}) is light enough generate an attractive force between fermions. We report herein search J^{PC}=1^{--} darkonium state, ϒ_{D}, produced...
A new mechanism has been proposed to simultaneously explain the presence of dark matter and matter-antimatter asymmetry in universe. This scenario predicts exotic $B$ meson decays into a baryon sector anti-baryon ($ψ_D$) with branching fractions accessible at factories. We present search for $B \rightarrow Λψ_D$ using data collected by $BABAR$ experiment SLAC. reaction is identified fully reconstructing accompanying requiring single $Λ$ remaining particles. No significant signal observed,...
Using the entire <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mi mathvariant="normal">ϒ</a:mi><a:mo stretchy="false">(</a:mo><a:mn>4</a:mn><a:mi>S</a:mi><a:mo stretchy="false">)</a:mo></a:math> dataset, first two-dimensional unbinned angular analysis of semileptonic decay <f:math xmlns:f="http://www.w3.org/1998/Math/MathML" display="inline"><f:mover accent="true"><f:mi>B</f:mi><f:mo stretchy="false">¯</f:mo></f:mover><f:mo...
We study the processes $e^+e^-\to 2(\pi^+\pi^-)\pi^0\pi^0\pi^0\gamma$ and $2(\pi^+\pi^-)\pi^0\pi^0\eta\gamma$ in which an energetic photon is radiated from initial state. The data were collected with \babar~ detector at SLAC. About 14\,000 4700 events, respectively, are selected a sample corresponding to integrated luminosity of 469 fb^{-1}. invariant mass hadronic final state defines effective \epem center-of-mass energy. energies range threshold 4.5 GeV. From spectra, first ever...
We present a new technique, ``tau polarimetry,'' for measuring the longitudinal beam polarization in an ${e}^{+}{e}^{\ensuremath{-}}$ collider through analysis of ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{\ensuremath{\tau}}^{+}{\ensuremath{\tau}}^{\ensuremath{-}}$ events. By exploiting sensitivity $\ensuremath{\tau}$ decay kinematics to beams, we demonstrate that can be measured with 3 per mil systematic uncertainty at interaction point using technique is independent spin and...
Using the entire BaBar $Υ(4S)$ data set, first two-dimensional unbinned angular analysis of semileptonic decay $\overline{B} \rightarrow D \ell^- \overlineν_\ell$ is performed, employing hadronic reconstruction tag-side $B$ meson from $Υ(4S)\to B\overline{B}$. Here, $\ell$ denotes light charged leptons $e$ and $μ$. A novel data-driven signal-background separation procedure with minimal dependence on simulation developed. This preserves all multi-dimensional correlations present in data. The...
We study the process $e^+e^-\to e^+e^- \eta'$ in double-tag mode and measure for first time $\gamma^{\star}\gamma^{\star} \to transition form factor $F_{\eta'}(Q_1^2, Q_2^2)$ momentum-transfer range \mbox{2 $<Q_1^2, Q_2^2<$ 60 GeV$^2$}. The analysis is based on a data sample corresponding to an integrated luminosity of around 469 fb$^{-1}$ collected at PEP-II $e^+e^-$ collider with BaBar detector center-of-mass energies near 10.6 GeV.