arXiv subjects

A. Drutskoy

Publications and source records attributed to A. Drutskoy.

118 records · Page 7Linked to original sources

arXiv2007

B_s decays at Belle

We report recent results obtained with the Belle detector using a 23.6 fb^{-1} data sample collected on the Y(5S) resonance at the KEKB asymmetric energy e^+ e^- collider. Inclusive semileptonic B_s^0 -> X^+ l^- νdecays are studied for the first time and the branching fraction is measured. Combining the electron and muon channels, we obtain Bf(B_s^0 -> X^+ l^- ν) = (10.2 \pm 0.8 \pm 0.9)%. Also, the radiative penguin decay B_s^0 -> ϕγis observed for the first time, and an improved upper limit for the decay B_s^0 \to γγis obtained.

hep-ex↗

arXiv2007

Measurement of inclusive $D_s$, $D^0$, and $J/ψ$ rates and determination of the $B_s^{()} \bar{B}_s^{()}$ production fraction in $b \bar{b}$ events at the Y(5S) resonance

The inclusive production of $D_s$, $D^0$, and $J/ψ$ mesons is studied using a 1.86 fb$^{-1}$ data sample collected on the $Υ$(5S) resonance by the Belle detector at the KEKB asymmetric energy $e^+ e^-$ collider. The number of $b\bar{b}$ events in the $Υ$(5S) data sample is determined. We measure the branching fractions $B(Υ({\rm 5S}) \to D_s X) / 2 = (23.6 \pm 1.2 \pm 3.6)%$, $B(Υ({\rm 5S}) \to D^0 X) / 2 = (53.8 \pm 2.0 \pm 3.4)%$}, and $B(Υ({\rm 5S}) \to J/ψX) / 2 = (1.030 \pm 0.080 \pm 0.067)%$. From the $D_s$ and $D^0$ inclusive branching fractions the ratio $f_s = (18.0 \pm 1.3 \pm 3.2)%$} of $B_s^{(*)} \bar{B}_s^{(*)}$ to the total $b\bar{b}$ quark pair production at the $Υ$(5S) energy is obtained in a model-dependent way.

hep-ex↗

arXiv2006

Results from the Y(5S) engineering run (BELLE)

We report results based on a 1.86 fb$^{-1}$ data sample collected on the $Υ$(5S) resonance by the Belle detector at the KEKB asymmetric energy $e^+ e^-$ collider. The inclusive production of $D_s$, $D^0$ and $J/ψ$ mesons at the $Υ$(5S) is studied. From the $D_s$ inclusive branching fraction the ratio $f_s = (16.4 \pm 1.4 \pm 4.1)%$ of $B_s^{(*)} \bar{B}_s^{(*)}$ to the total $b\bar{b}$ quark pair production at the $Υ$(5S) energy is obtained in a model dependent way. The exclusive decays $B_s \to D_s^{(*)+} π^- (/ρ^-)$ and $B_s \to J/Ψϕ(/η)$ are studied and a significant $B_s$ signal is observed combining these modes. The $B_s$ meson production is found to proceed predominantly through the creation of $B^*_s \bar{B}^*_s$ pairs. Upper limits on $B_s \to K^+ K^-$, $B_s \to ϕγ$, $B_s \to γγ$ and $B_s \to D_s^{(*)+} D_s^{(*)-}$ decays are reported.

hep-ex↗

arXiv2006

Determining Delta_Gamma_s / Gamma_s from Bf(B_s \to D_s^{()+} D_s{()-}) measurements at e^+ e^- colliders running on the Y(5S) resonance

The feasibility of determining $ΔΓ_s / Gamma_s$ from $B_s \to D_s^{(*)+} D_s^{(*)-}$ decay branching fraction measurements at $e^+ e^-$ colliders running on the $Υ$(5S) resonance is discussed. The expected accuracies of the $B_s \to D_s^{(*)+} D_s^{(*)-}$ branching fraction measurements and the $ΔΓ_s / Γ_s$ determination with 50fb$^{-1}$ of data at the $Υ$(5S) are estimated using Monte Carlo simulation. Comparison of that measurement with a directly measured $ΔΓ_s / Γ_s$ value within and beyond Standard Model is discussed. A new method of estimating $ΔΓ_s / Γ_s$ is proposed, based on comparing the CP-even and CP-odd components in $B^0 \to J/ΨK^{*0}$ and $B_s \to J/Ψϕ$ decays. A comparison of $B_s$ and $B^0$ lifetime measurements with theoretical predictions is discussed.

hep-ph↗

arXiv2005

Observation of $\bar{B^0}$ -> DsJ*(2317)+ K- decay

The decays $\bar{B^0} \to D_{sJ}^+ K^-$ and $\bar{B^0} \to D_{sJ}^- π^+$ are studied for the first time. A significant signal is observed in the $\bar{B^0} \to D_{sJ}^*(2317)^+ K^-$ decay channel with ${\cal B}(\bar{B^0} \to D_{sJ}^*(2317)^+ K^-) \times {\cal B} (D_{sJ}^*(2317)^+ \to D_s^+ π^0) = (5.3^{+1.5}_{-1.3} \pm 0.7 \pm 1.4) \times 10^{-5}$. No signals are observed in the $\bar{B^0} \to D_{sJ}^*(2317)^- π^+$, $\bar{B^0} \to D_{sJ}(2460)^+ K^-$ and $\bar{B^0} \to D_{sJ}(2460)^- π^+$ decay modes, and upper limits are obtained. The analysis is based on a dataset of 140 fb$^{-1}$ collected by the Belle experiment at the asymmetric $e^+ e^-$ collider KEKB.

hep-ex↗

arXiv2004

Properties of the DsJ states

Recent measurements involving the newly discovered D_sJ particles are reported. The results of D_sJ production and decay branching fraction measurements are shown. Possible spin-parity and quark content assignments of D_sJ mesons are discussed. The results are based on a large data sample recorded by the Belle detector at the KEKB e^+ e^- collider.

hep-ex↗

arXiv2004

B decays to open and hidden charm at Belle

The recent Belle collaboration measurements of B decays to open and hidden charm are discussed. Color-suppressed decay branching fractions are measured with an improved accuracy. The branching fractions of the $\bar{B}^0 \to D_s^+ K^-$ and $\bar{B}^0 \to D_s^- π^+$ decays, measured with improved accuracy, and $\bar{B}^0 \to D_{sJ}^+ K^-$ and $\bar{B}^0 \to D_{sJ}^- π^+$ decays, measured for the first time, are compared. The two-body invariant masses of the three-body $B^0 \to D^{(*)0} π^+ π^-$ and $B^0 \to J/Ψπ^+ π^-$ decays are studied.

hep-ex↗

arXiv2004

Physics at Super B Factory

This report presents the results of studies that investigate the physics reach at a Super B factory, an asymmetric-energy e^+e^- collider with a design luminosity of 5 x 10^35 cm^-2s^-1, which is around 40 times as large as the peak luminosity achieved by the KEKB collider. The studies focus on flavor physics and CP violation measurements that could be carried out in the LHC era. The physics motivation, key observables, measurement methods and expected precisions are presented. The sensitivity studies are a part of the activities associated with the preparation of a Letter of Intent for SuperKEKB, which has been submitted recently.

hep-ex↗

arXiv2003

Observation of radiative B -> phi K gamma decays

The radiative decay $B \to ϕK γ$ is observed for the first time. The branching fraction for the charged $B^- \to ϕK^- γ$ decay mode is measured to be ${\cal B}(B^- \to ϕK^- γ) = (3.4 \pm 0.9 \pm 0.4) \times 10^{-6}$. The photon energy distribution for the $B^- \to ϕK^- γ$ decay is presented. The signal for the neutral $\bar{B}^0 \to ϕ\bar{K}^0 γ$ decay mode is not statistically significant and an upper limit, ${\cal B}(\bar{B}^0 \to ϕ\bar{K}^0 γ) < 8.3 \times 10^{-6}$ at $90% {\rm CL}$, is set. The analysis is based on a dataset of 90 fb$^{-1}$ collected by the Belle experiment at the $e^+ e^-$ asymmetric collider KEKB.

hep-ex↗

arXiv2002

Observation of B -> D^{()} K^- K^{0()} decays

The B -> D^{(*)} K^- K^{(*)0} decays have been observed for the first time. The branching fractions of the B -> D^{(*)} K^- K^{(*)0} decay modes are measured. Significant signals are found for the B -> D^{(*)} K^- K^{*0} and B^- -> D^0 K^- K^0_S decay modes. The invariant mass and polarization distributions for the K^-K^{*0} and K^-K^0_S subsystems have been studied. For the K^-K^{*0} sybsystem these distributions agree well with those expected for two-body B -> D^{(*)} a_1^-(1260) decays, with a_1^-(1260) -> K^- K^{*0}. The analysis was done using 29.4 fb^{-1} of data collected with the Belle detector at the e^+ e^- asymmetric collider KEKB.

hep-ex↗