G. Ghevondyan
A5065599552- Particle physics theoretical and experimental studies
- Quantum Chromodynamics and Particle Interactions
- High-Energy Particle Collisions Research
- Neutrino Physics Research
- Computational Physics and Python Applications
- Dark Matter and Cosmic Phenomena
- Particle Detector Development and Performance
- Black Holes and Theoretical Physics
- Medical Imaging Techniques and Applications
- Radiation Detection and Scintillator Technologies
- Nuclear physics research studies
- Superconducting Materials and Applications
- Atomic and Subatomic Physics Research
- Calibration and Measurement Techniques
- NMR spectroscopy and applications
- Scientific Measurement and Uncertainty Evaluation
- Particle Accelerators and Free-Electron Lasers
- Advanced NMR Techniques and Applications
A. Alikhanyan National Laboratory
2023
A bstract Using data samples of 983.0 fb − 1 and 427.9 accumulated with the Belle II detectors operating at KEKB SuperKEKB asymmetric-energy e + colliders, singly Cabibbo-suppressed decays $$ {\Xi}_c^{+}\to p{K}_S^0 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>Ξ</mml:mi> <mml:mi>c</mml:mi> <mml:mo>+</mml:mo> </mml:msubsup> <mml:mo>→</mml:mo> <mml:mi>p</mml:mi> <mml:mi>K</mml:mi> <mml:mi>S</mml:mi> <mml:mn>0</mml:mn> </mml:math> , \Lambda {\pi}^{+}...
We study the processes e^{+}e^{-}→ωχ_{bJ}(1P) (J=0, 1, or 2) using samples at center-of-mass energies sqrt[s]=10.701, 10.745, and 10.805 GeV, corresponding to 1.6, 9.8, 4.7 fb^{-1} of integrated luminosity, respectively. These data were collected with Belle II detector during special operations SuperKEKB collider above ϒ(4S) resonance. report first observation ωχ_{bJ}(1P) signals sqrt[s]=10.745 GeV. By combining results sqrt[s]=10.867 we find energy dependencies Born cross sections for...
We present the first measurement of ratio branching fractions inclusive semileptonic B-meson decays, R(X_{e/μ})=B(B→Xeν)/B(B→Xμν), a precision test electron-muon universality, using data corresponding to 189 fb^{-1} from electron-positron collisions collected with Belle II detector. In events where partner B meson is fully reconstructed, we use fits lepton momentum spectra above 1.3 GeV/c obtain R(X_{e/μ})=1.007±0.009(stat)±0.019(syst), which most precise lepton-universality its kind and...
We measure the time-integrated <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mi>C</a:mi><a:mi>P</a:mi></a:math> asymmetry in <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:msup><c:mi>D</c:mi><c:mn>0</c:mn></c:msup><c:mo stretchy="false">→</c:mo><c:msubsup><c:mi>K</c:mi><c:mi>S</c:mi><c:mn>0</c:mn></c:msubsup><c:msubsup><c:mi>K</c:mi><c:mi>S</c:mi><c:mn>0</c:mn></c:msubsup></c:math> decays reconstructed <f:math...
A bstract We perform the first search for CP violation in $$ {D}_{(s)}^{+}\to {K}_S^0{K}^{-}{\pi}^{+}{\pi}^{+} <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>D</mml:mi> <mml:mfenced> <mml:mi>s</mml:mi> </mml:mfenced> <mml:mo>+</mml:mo> </mml:msubsup> <mml:mo>→</mml:mo> <mml:mi>K</mml:mi> <mml:mi>S</mml:mi> <mml:mn>0</mml:mn> <mml:msup> <mml:mo>−</mml:mo> </mml:msup> <mml:mi>π</mml:mi> </mml:math> decays. use a combined data set from Belle and II experiments,...
We present a measurement of the branching fraction and longitudinal polarization <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:msup><a:mrow><a:mi>B</a:mi></a:mrow><a:mrow><a:mn>0</a:mn></a:mrow></a:msup><a:mo stretchy="false">→</a:mo><a:msup><a:mrow><a:mi>ρ</a:mi></a:mrow><a:mrow><a:mo>+</a:mo></a:mrow></a:msup><a:msup><a:mrow><a:mi>ρ</a:mi></a:mrow><a:mrow><a:mo>−</a:mo></a:mrow></a:msup></a:mrow></a:math> decays, which have two <d:math...
We report on a measurement of the $\Omega_c^0$ lifetime using $\Omega_c^0 \to \Omega^-\pi^+$ decays reconstructed in $e^+e^-\to c\bar{c}$ data collected by Belle II experiment and corresponding to $207~{\rm fb^{-1}}$ integrated luminosity. The result, $\rm\tau(\Omega_c^0)=243\pm48( stat)\pm11(syst)~fs$, agrees with recent measurements indicating that is not shortest-lived weakly decaying charmed baryon.
We present a measurement of the branching fraction $B^+\to\tau^+\nu_\tau$ decays using $(387\pm6)\times 10^6$ $\Upsilon(4S)$ collected between 2019 and 2022 with Belle II detector at SuperKEKB $e^+e^-$ collider. reconstruct accompanying $B^-$ meson hadronic tagging method, while candidates are identified in recoil. find evidence for 3.0 standard deviations, including systematic uncertainties. The measured is $\mathcal{B}(B^+\to\tau^+\nu_\tau) = [1.24 \pm 0.41 (\text{stat.}) 0.19...
We perform a model-independent measurement of the $D^0$-$\overline{D}{}^0$ mixing parameters using samples $e^+e^-$-collision data collected by Belle and II experiments that have integrated luminosities $951\ \text{fb}^{-1}$ $408\ \text{fb}^{-1}$, respectively. Approximately $2.05\times10^6$ neutral $D$ mesons are reconstructed in $D^0\rightarrow K^0_{S}\pi^+\pi^-$ channel, with flavor tagged charge pion $D^{*+}\rightarrow D^0\pi^+$ decay. Assuming charge-parity symmetry, measured to be $ x...
We measure the time-integrated CP asymmetry in $D^{0} \rightarrow K^{0}_{S}K^{0}_{S}$ decays reconstructed $e^{+}e^{-} c\overline{c}$ events collected by Belle and II experiments. The corresponding data samples have integrated luminosities of 980 fb$^{-1}$ 428 fb$^{-1}$, respectively. $D^{0}$ are required to originate from $D^{*+} D^{0}\pi^{+}$ decay, which determines charm flavor at production time. A control sample K^{+}K^{-}$ is used correct for detection asymmetries. result,...
Since 2018, an Proximity Focusing Aerogel Ring Imaging Detector (ARICH) efficiently separates hadrons in the forward end-cap of Belle II spectrometer. Cherenkov photons emitted double-layer aerogel radiator are expanded 16-cm space and detected on photon detector, which consists 420 hybrid avalanche photodiodes rear readout electronics operating threshold mode. Each sensors requires six different high voltages a supply four low for electronics. Because power dissipation, system also includes...