(SVD-2 Collaboration) A. G. Afonin, E. N. Ardashev, V. F. Golovkin, S. N. Golovnya, S. A. Gorokhov, A. A. Kiryakov, A. G. Kholodenko, V. V. Konstantinov, L. L. Kurchaninov, I. S. Lobanov, E. V. Lobanova, G. A. Mitrofanov, V. S. Petrov, A. V. Pleskach, M. K. Polkovnikov, V. N. Riadovikov*, V. N. Ronzhin, V. A. Senko,N. A. Shalanda, M. M. Soldatov, Yu. P. Tsyupa, A. P. Vorobiev, V. I. Yakimchuk, and V. N. Zapolskii∗ IHEP, Protvino, Moscow region, Russia.

Limits on anomalous WWg and WWZ couplings from WWÕWZ\en j j production B. Abbott, M. Abolins, V. Abramov, B. S. Acharya, 13 D. L. Adams, 54 M. Adams, 30 S. Ahn, V. Akimov, G. A. Alves, N. Amos, E. W. Anderson, 36 M. M. Baarmand, 49 V. V. Babintsev, 19 L. Babukhadia, 49 A. Baden, 40 B. Baldin, S. Banerjee, 13 J. Bantly, 53 E. Barberis, 22 P. Baringer, 37 J. F. Bartlett, 29 U. Bassler, 9 A. Belyaev, 18 S. B. Beri, G. Bernardi, 9 I. Bertram, 20 V. A. Bezzubov, 19 P. C. Bhat, 29 V. Bhatnagar, 11 M. Bhattacharjee, 49 G. Blazey, 31 S. Blessing, 27

The results of an analysis of data from the SERP-Е-184 experiment devoted to studying mechanisms of the production of charmed particles in proton–nucleus interactions at 70 GeV and their decays are presented. The data in question were obtained upon irradiating the SVD-2 active target consisting of carbon, silicon, and lead plates with a beam of 70-GeV protons. A detailed simulation on the basis of the FRITIOF7.02 and GEANT3.21 code packages made it possible to optimize event-selection criteria and to calculate the detection efficiency for Λ c + baryons. After selecting a signal from the threebody decay of a Λ c + baryon, the inclusive cross section for its production at near-threshold energies, its lifetime, and the parameter of the A dependence of the cross section were found. The Λ c + -baryon yields are tabulated along with data from other experiments and theoretical predictions.

The stages of development and the current status of the versatile “Spectrometer with a Vertex Detector” setup designed for physics experiments at the U-70 accelerator of the Institute for High Energy Physics (Protvino) is described. The main detectors of the setup are the vertex detector based on silicon microstrip detectors, the wide-aperture magnetic spectrometer based on multiwire proportional chambers, and the lead-glass hodoscope γ detector. In the setup, there is a fast two-level trigger system for selecting required particle interactions. The key characteristics of the setup systems are presented, and the physical results obtained on it are briefly listed.

Описаны этапы развития и современное состояние многоцелевой установки “Спектрометр с вершинным детектором”, созданной для проведения физических экспериментов на ускорителе У-70 Института физики высоких энергий (Протвино). Основными детекторами установки являются: вершинный детектор на основе кремниевых микростриповых детекторов, широкоапертурный магнитный спектрометр на основе пропорциональных камер, годоскопический детектор -квантов, собранный из свинцовых стекол. Для отбора нужных взаимодействий частиц в установке имеется быстродействующая двухуровневая система запуска. Приведены основные характеристики созданных систем установки, кратко перечислены полученные физические результаты.

Measurement of mixing-induced CP violation in B¯s0 decays is of prime importance in probing new physics. So far only the channel B¯s0→J/ψϕ has been used. Here we report on a measurement using an LHCb data sample of 0.41 fb−1, in the CP odd eigenstate J/ψf0(980), where f0(980)→π+π−. A time-dependent fit of the data with the B¯s0 lifetime and the difference in widths of the heavy and light eigenstates constrained to the values obtained from B¯s0→J/ψϕ yields a value of the CP violating phase of −0.44±0.44±0.02 rad, consistent with the Standard Model expectation.

The first observation of the decay ⁎B¯s0→D0K⁎0 using pp data collected by the LHCb detector at a centre-of-mass energy of 7 TeV, corresponding to an integrated luminosity of 36pb−1, is reported. A signal of 34.4±6.8 events is obtained and the absence of signal is rejected with a statistical significance of more than nine standard deviations. The ⁎B¯s0→D0K⁎0 branching fraction is measured relative to that of B¯0→D0ρ0: ⁎B(B¯s0→D0K⁎0)B(B¯0→D0ρ0)=1.48±0.34±0.15±0.12, where the first uncertainty is statistical, the second systematic and the third is due to the uncertainty on the ratio of the B0 and Bs0 hadronisation fractions.

The first observation of the decay (B) over bar (0)(S) -> (DK)-K-0*(0) using pp data collected by the LHCb detector at a centre-of-mass energy of 7 TeV, corresponding to an integrated luminosity of 36 pb(-1), is reported. A signal of 34.4 +/- 6.8 events is obtained and the absence of signal is rejected with a statistical significance of more than nine standard deviations. The (B) over bar (0)(S) -> (DK)-K-0*(0) branching fraction is measured relative to that of (B) over bar (0) -> D-0 rho(0): B((B) over bar (0)(S)->(DK)-K-0*(0))/B((B) over bar (0)-> D-0 rho(0)) = 1.48+/-0.34+/-0.15+/-0.12, where the first uncertainty is statistical, the second systematic and the third is due to the uncertainty on the ratio of the B-0 and B-s(0) hadronisation fractions. (C) 2011 CERN. Published by Elsevier B.V. All rights reserved.

We have performed a search for CP violation in a sample of Bs -> Ds mu X decays corresponding to $5$~fb$^{-1}$ of proton-antiproton collisions collected by the D0 detector in Run~II at the Fermilab Tevatron Collider. New physics in $B_s^0$ mixing could contribute a significant CP violating weak phase, which would be observed as a difference in the decay-time distribution for $B_s^0\to \bar{B}_s^0$ oscillated states versus that for $\bar{B}_s^0\to {B}_s^0$. A fit to the decay-time distributions of the $B_s^0/\bar{B}_s^0$ candidates yields the flavor-specific asymmetry $a_{fs}^{s}=[-1.7\pm 9.1\mathrm{(stat)}^{+1.4}_{-1.5}\mathrm{(syst)}] \times 10^{-3}$, which excludes CP violation due to new physics within the experimental sensitivity.

Branching fractions of the decays ${H}_{b}\ensuremath{\rightarrow}{H}_{c}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}$ relative to ${H}_{b}\ensuremath{\rightarrow}{H}_{c}{\ensuremath{\pi}}^{\ensuremath{-}}$ are presented, where ${H}_{b}$ (${H}_{c}$) represents ${\overline{B}}^{0}$ (${D}^{+}$), ${B}^{\ensuremath{-}}$ (${D}^{0}$), ${\overline{B}}_{s}^{0}$ (${D}_{s}^{+}$), and ${\ensuremath{\Lambda}}_{b}^{0}$ (${\ensuremath{\Lambda}}_{c}^{+}$). The measurements are performed with the LHCb detector using $35\text{ }\text{ }{\mathrm{pb}}^{\ensuremath{-}1}$ of data collected at $\sqrt{s}=7\text{ }\text{ }\mathrm{TeV}$. The ratios of branching fractions are measured to be $[\mathcal{B}({\overline{B}}^{0}\ensuremath{\rightarrow}{D}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}})]/[\mathcal{B}({\overline{B}}^{0}\ensuremath{\rightarrow}{D}^{+}{\ensuremath{\pi}}^{\ensuremath{-}})]=2.38\ifmmode\pm\else\textpm\fi{}0.11\ifmmode\pm\else\textpm\fi{}0.21$, $[\mathcal{B}({B}^{\ensuremath{-}}\ensuremath{\rightarrow}{D}^{0}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}})]/[\mathcal{B}({B}^{\ensuremath{-}}\ensuremath{\rightarrow}{D}^{0}{\ensuremath{\pi}}^{\ensuremath{-}})]=\phantom{\rule{0ex}{0ex}}1.27\ifmmode\pm\else\textpm\fi{}0.06\ifmmode\pm\else\textpm\fi{}0.11$, $[\mathcal{B}({\overline{B}}_{s}^{0}\ensuremath{\rightarrow}{D}_{s}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}})]/[\mathcal{B}({\overline{B}}_{s}^{0}\ensuremath{\rightarrow}{D}_{s}^{+}{\ensuremath{\pi}}^{\ensuremath{-}})]=2.01\ifmmode\pm\else\textpm\fi{}0.37\ifmmode\pm\else\textpm\fi{}0.20$, $[\mathcal{B}({\ensuremath{\Lambda}}_{b}^{0}\ensuremath{\rightarrow}{\ensuremath{\Lambda}}_{c}^{+}{\ensuremath{\pi}}^{\ensuremath{-}}\phantom{\rule{0ex}{0ex}}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{\ensuremath{-}})]/[\mathcal{B}({\ensuremath{\Lambda}}_{b}^{0}\ensuremath{\rightarrow}{\ensuremath{\Lambda}}_{c}^{+}{\ensuremath{\pi}}^{\ensuremath{-}})]=1.43\ifmmode\pm\else\textpm\fi{}0.16\ifmmode\pm\else\textpm\fi{}0.13$ We also report measurements of partial decay rates of these decays to excited charm hadrons. These results are of comparable or higher precision than existing measurements.

Using data collected with the LHCb detector in proton-proton collisions at a centre-ofmass energy of 7 TeV, the semileptonic decays B 0 s → D + s Xμ ν and B 0 s → D KXμν are detected. Two structures are observed in the DK mass spectrum at masses consistent with the known Ds1(2536) + and D s2(2573) + mesons. The measured branching fractions relative to the total B 0 s semileptonic rate are B(B 0 s → D ∗+ s2 Xμ ν)/B(B 0 s → Xμ ν) = (3.3± 1.0± 0.4)%, and B(B 0 s → D + s1Xμ ν)/B(B 0 s → Xμ ν) = (5.4± 1.2± 0.5)%, where the first uncertainty is statistical and the second is systematic. This is the first observation of the D s2 state in B 0 s decays; we also measure its mass and width.