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V. B. Golubev

Publications and source records attributed to V. B. Golubev.

At least 55 records · Page 3Linked to original sources
arXiv2012

A Measurement of the Semileptonic Branching Fraction of the B_s Meson

We report a measurement of the inclusive semileptonic branching fraction of the B_s meson using data collected with the BaBar detector in the center-of-mass (CM) energy region above the Upsilon(4S) resonance. We use the inclusive yield of phi mesons and the phi yield in association with a high-momentum lepton to perform a simultaneous measurement of the semileptonic branching fraction and the production rate of B_s mesons relative to all B mesons as a function of CM energy. The inclusive semileptonic branching fraction of the B_s meson is determined to be B(B_s to l nu X)=9.5 (+2.5/-2.0)(stat)(+1.1/-1.9)(syst)%, where l indicates the average of e and mu.

hep-ex↗
arXiv2011

Study of radiative bottomonium transitions using converted photons

We use 111+/-1 million Upsilon(3S) and 89+/-1 million Upsilon(2S) events recorded by the BaBar detector at the PEP-II B-factory at SLAC to perform a study of radiative transitions between bottomonium states using photons that have been converted to e+e- pairs by the detector material. We observe Upsilon(3S) -> gamma chi_b0,2(1P) decay, make precise measurements of the branching fractions for chi_b1,2(1P,2P) -> gamma Upsilon(1S) and chi_b1,2(2P) -> gamma Upsilon(2S) decays, and search for radiative decay to the eta_b(1S) and eta_b(2S) states.

hep-ex↗
arXiv2011

Evidence for the h_b(1P) meson in the decay Upsilon(3S) --> pi0 h_b(1P)

Using a sample of 122 million Upsilon(3S) events recorded with the BaBar detector at the PEP-II asymmetric-energy e+e- collider at SLAC, we search for the $h_b(1P)$ spin-singlet partner of the P-wave chi_{bJ}(1P) states in the sequential decay Upsilon(3S) --> pi0 h_b(1P), h_b(1P) --> gamma eta_b(1S). We observe an excess of events above background in the distribution of the recoil mass against the pi0 at mass 9902 +/- 4(stat.) +/- 2(syst.) MeV/c^2. The width of the observed signal is consistent with experimental resolution, and its significance is 3.1sigma, including systematic uncertainties. We obtain the value (4.3 +/- 1.1(stat.) +/- 0.9(syst.)) x 10^{-4} for the product branching fraction BF(Upsilon(3S)-->pi0 h_b) x BF(h_b-->gamma eta_b).

hep-ex↗
arXiv2011

Search for hadronic decays of a light Higgs boson in the radiative decay Upsilon --> gamma A0

We search for hadronic decays of a light Higgs boson (A0) produced in radiative decays of an Upsilon(2S) or Upsilon(3S) meson, Upsilon --> gamma A0. The data have been recorded by the BABAR experiment at the Upsilon(3S) and Upsilon(2S) center of mass energies, and include (121.3 \pm 1.2) x 10^6 Upsilon(3S) and (98.3 \pm 0.9) x 10^6 Upsilon(2S) mesons. No significant signal is observed. We set 90% confidence level upper limits on the product branching fractions B(Upsilon(nS)-->gamma A0) x B(A0-->hadrons) (n=2 or 3) that range from 1 x 10^{-6} for an A0 mass of 0.3 GeV/c^2 to 8 x 10^{-5} at 7 GeV/c^2.

hep-ex↗
arXiv2011

Observation of the baryonic B decay B0bar --> Lambda_c^+ anti-Lambda K-

We report the observation of the baryonic B decay B0bar --> Lambda_c^+ anti-Lambda K- with a significance larger than 7 standard deviations based on 471x10^6$ BBbar pairs collected with the BABAR detector at the PEP-II storage ring at SLAC. We measure the branching fraction for the decay B0bar --> Lambda_c^+ anti-Lambda K- to be (3.8 \pm 0.8_{stat} \pm 0.2_{sys} \pm 1.0_{Lambda_c^+})x10^{-5}. The uncertainties are statistical, systematic, and due to the uncertainty in the Lambda_c^+ branching fraction. We find that the Lambda_c^+ K^- invariant mass distribution shows an enhancement above 3.5 GeV/c^2.

hep-ex↗
arXiv2009

Search for Lepton Flavor Violation Process e^+e^- \to eμin the Energy Region \sqrt{s}=984 -- 1060 MeV and ϕ\to eμDecay

The search for lepton-flavor-violation process e^+e^-\to eμin the energy region \sqrt{s}=984 - 1060 MeV with SND detector at VEPP-2M e^+e^- collider is reported. The model independent 90% CL upper limits on the e^+e^-\to eμcross section, σ_{eμ} < 11 pb, as well as on the corresponding ϕ\to eμbranching fraction, B(ϕ\to eμ) < 2 \times 10^{-6}, for the final particles polar angles 55^\circ<θ<125^\circ, were obtained.

hep-ex↗
arXiv2008

Study of the process e+e-\to μ+μ- in the energy region \sqrt{s}=980, 1040 -- 1380 MeV

The cross section of the process e+e-\toμ+μ- was measured in the SND experiment at the VEPP-2M e+e- collider in the energy region \sqrt{s}=980, 1040 -- 1380 MeV. The event numbers of the process e+e-\toμ+μ- were normalized to the integrated luminosity measured using e+e-\to e+e- and e+e-\toγγprocesses. The ratio of the measured cross section to the theoretically predicted value is 1.006\pm 0.007 \pm 0.016 and 1.005 \pm 0.007 \pm 0.018 in the first and second case respectively. Using results of the measurements, the electromagnetic running coupling constant αin the energy region \sqrt{s}=1040 -- 1380 MeV was obtained <1/α> = 134.1\pm 0.5 \pm 1.2 and this is in agreement with theoretical expectation.

hep-ex↗
arXiv2008

Investigation of the $e^+e^- \to ωπ^0 \to π^0 π^0 γ$ reaction in the energy domain near the $ϕ$-meson

The $e^+e^- \to ωπ^0 \to π^0 π^0 γ$ process was investigated in the SND experiment at the VEPP-2M collider. A narrow energy interval near the $ϕ$-meson was scanned. The observed cross-section reveals, at the level of three standard deviation, the interference effect caused by $ϕ\to π^0π^0γ$ decay. The cross-section parameters, as well as the real and imaginary parts of the $ϕ$-meson related amplitude, were measured.

hep-ex↗
arXiv2007

Measurement of the e+e- -> K+K- cross section in the energy range s**(1/2) = 1.04 - 1.38 GeV with the SND detector in the experiment at the VEPP-2M e+e- collider

The cross section of the process $e^+e^- \to K^+K^-$ was measured in the energy range $\sqrt{s}$ = 1.04--1.38 GeV in the SND experiment at the VEPP-2M $e^+e^-$ collider. The measured cross section is described by the model of vector meson dominance with contributions from the light vector mesons $ρ$, $ω$, $ϕ$ and their lowest excitations. The mean statistical accuracy of the measurement is 4.4 %, and the systematic uncertainty is 5.2 %.

hep-ex↗
arXiv2007

Extraction of |Vub| with Reduced Dependence on Shape Functions

Using BaBar measurements of the inclusive electron spectrum in B->X_u e nu decays and the inclusive photon spectrum in B->X_s gamma decays, we extract the magnitude of the CKM matrix element Vub. The extraction is based on theoretical calculations designed to reduce the theoretical uncertainties by exploiting the assumption that the leading shape functions are the same for all b->q transitions (q is a light quark). The results agree well with the previous analysis, have indeed smaller theoretical errors, but are presently limited by the knowledge of the photon spectrum and the experimental errors on the lepton spectrum.

hep-ph↗
arXiv2007

Reanalysis of the $e^+e^-\toηγ$ reaction cross section

In the experiment with the SND detector at the VEPP-2M $e^+e^-$ collider measuring the $e^+e^-\to ηγ$ cross section in the energy range $0.6<\sqrt{s}<1.38 \mathrm{GeV}$ the reanalysis of data is performed. The goal is to improve the accuracy of the previous results by analysing ambiguities in the approximation of energy dependence of the $e^+e^-\to ηγ$ cross section, which were not taken into account in our previous study. We report new results on the approximation of the $e^+e^-\to ηγ$ cross section based on Vector Dominance Model under new model parameter assumptions.

hep-ex↗
arXiv2006

Study of the $e^+e^-\toηγ$ process with SND detector at the VEPP-2M $e^+e^-$ collider

In experiment with the SND detector at VEPP-2M $e^+e^-$ collider the $e^+e^-\toηγ$ cross section was measured in the energy range $E$=0.60--1.38 GeV with the integrated luminosity of 27.8 pb$^{-1}$. The measured cross section is well described by the vector meson dominance model with contributions from the $ρ(770)$, $ω(783)$, $ϕ(1020)$, $ρ^{\prime}(1465)$ resonances and agrees with results of previous measurements. The decay probabilities $\BR(ϕ\toηγ)$, $\BR(ω\toηγ)$ and $\BR(ρ\toηγ)$ were measured with the accuracies better than or comparable to the world averages.

hep-ex↗
arXiv2006

Pion Form Factor at SND (new edition)

The update of the e^+e^-\toπ^+π^- process cross section, measured in the energy region \sqrt{s}<1 GeV with SND detector at VEPP-2M collider is presented.

hep-ex↗
arXiv2005

New results on e+e- -> hadrons exclusive cross sections from experiments with SND detector at VEPP-2M e+e- collider in the energy range sqrt(s)=0.4-1.4 GeV

New results of the e+e- -> pi+pi-, K+K-, K_SK_L, pi0/gamma, eta0/gamma processes cross section measurements are presented. The results are based on the 30 pb^-1 data, accumulated by SND detector at VEPP-2M e+e- collider in the energy range sqrt(s)=0.4-1.4 GeV during 1995-2000 years. The comparison with existing experimental data shows that the measurement accuracy is close to or better than the world average. For the e+e- -> pi+pi- process the accuracy is about 0.01. This is important for calculation of hadronic contribution into the muon anomalous magnetic moment.

hep-ex↗
arXiv2005

Study of the process $e^+e^- \to π^+π^-$ in the energy region 400<\sqrt[]{s}<1000 MeV

The cross section of the process e^+e^-\to π^+π^- was measured in the SND experiment at the VEPP-2M collider in the energy region 400<\sqrt[]{s}<1000 MeV. This measurement was based on about 12.4 \times 10^6 selected collinear events, which include 7.4\times 10^6 e^+e^-\to e^+e^-, 4.5\times 10^6 e^+e^-\toπ^+π^- and 0.5\times 10^6 e^+e^-\toμ^+μ^- selected events. The systematic uncertainty of the cross section determination is 1.3 %. The ρ-meson parameters were determined: m_ρ=774.9\pm 0.4\pm 0.5 MeV, Γ_ρ=146.5\pm 0.8\pm 1.5 MeV, σ(ρ\toπ^+π^-)=1220\pm 7\pm 16 nb as well as the parameters of the G-parity suppressed decay ω\toπ^+π^-: σ(ω\toπ^+π^-)=29.9\pm 1.4\pm 1.0 nb and ϕ_{ρω} = 113.5\pm 1.3\pm 1.7 degree.

hep-ex↗
arXiv2003

Study of the e^+e^-\toπ^0γprocess in the energy range 0.60-1.06 GeV

The process e^+e^-\toπ^0γin the energy range \sqrt{s}=0.60-1.06 GeV was studied at VEPP-2M collider with SND detector using 14 pb^{-1} of integrated luminosity. Data were analyzed in the framework of the vector meson dominance model. Preliminary results on obtained cross-section and parameters of ρ^0, ω,ϕ\to π^0γradiative decays are presented.

hep-ex↗