First observation of Bs -> J/psi f0(980) decays

Using data collected with the LHCb detector in proton-proton collisions at a centre-of-mass energy of 7 TeV, the hadronic decay Bs -> J/psi f0(980) is observed. This CP eigenstate mode could be used to measure mixing-induced CP violation in the B_s system. Using a fit to the pi+ pi- mass spectrum with interfering resonances gives R_{f0/phi} = [Gamma(Bs -> J/psi f0, f0 -> pi+ pi-)]/[Gamma(Bs -> J/psi phi, phi -> K+K-)] = 0.252^{+0.046+0.027}_{-0.032-0.033}, where the uncertainties are statistical and systematic, respectively

Measurement of CP observables in B0 -> D K*0 with D -> K+ K-

The decay B0 -> D K*0 and the charge conjugate mode are studied using 1.0fb-1 of pp collision data collected by the LHCb experiment at sqrt(s) = 7TeV in 2011. The CP asymmetry between the B0 -> D K*0 and the B0bar -> D K*0bar decay rates, with the neutral D meson in the CP-even final state K+K-, is found to be A_d_KK = -0.45 +- 0.23 +- 0.02, where the first uncertainty is statistical and the second is systematic. In addition, favoured B0 -> D K*0 decays are reconstructed with the D meson in the non-CP eigenstate K+ pi-. The ratio of the B-flavour averaged decay rates in D decays to CP and non-CP eigenstates is measured to be R_d_KK = 1.36 (+0.37) (-0.32) +- 0.07, where the ratio of the branching fractions of D0 -> K- pi+ to D0 -> K+ K- decays is included as multiplicative factor. The CP asymmetries measured with two control channels, the favoured B0 -> DK*0 decay with D -> K+ pi- and the Bs0bar -> D K*0 decay with D K+ K-, are also reported

Measurement of the branching fractions of the decays Bs -> D0bar K- π+ and B0 -> D0bar K+ π-

The first observation of the decay Bs -> D0bar K- {\pi}+ is reported. The analysis is based on a data sample, corresponding to an integrated luminosity of 1.0 fb-1 of pp collisions, collected with the LHCb detector. The branching fraction relative to that of the topologically similar decay B0 -> D0bar {\pi}+ {\pi}- is measured to be BR(Bs -> D0bar K- {\pi}+)/BR(B0 -> D0bar {\pi}+ {\pi}-) = 1.18 +- 0.05 (stat.) +- 0.12 (syst.). In addition, the relative branching fraction of the decay B0 -> D0bar K+ {\pi}- is measured to be BR(B0 -> D0bar K+ {\pi}-)/BR(B0 -> D0bar {\pi}+ {\pi}-) = 0.106 +- 0.007 (stat.) +- 0.008 (syst.)

First observation of the decay Bs0→φKˉ∗0B_s^0 \rightarrow φ\bar{K}^{*0}

The first observation of the decay $B_s^0 \rightarrow \phi \bar{K}^{*0}$ is reported. The analysis is based on a data sample corresponding to an integrated luminosity of 1.0 fb$^{-1}$ of $pp$ collisions at $\sqrt{s} = 7 TeV$, collected with the LHCb detector. A yield of $30 \pm 6$ $B_s^0 \rightarrow (K^+K^-)(K^-\pi^+)$ decays is found in the mass windows 1012.5 < M(K^+K^-) < 1026.5 MeV/c^2 and 746 < M(K^-\pi^+)< 1046 MeV/c^2. The signal yield is found to be dominated by $B_s^0 \rightarrow \phi \bar{K}^{*0}$ decays, and the corresponding branching fraction is measured to be ${\cal B}(B_s^0 \rightarrow \phi \bar{K}^{*0}) = (1.10 \pm 0.24 (stat) \pm 0.14 (syst) \pm 0.08 (f_d/f_s)) \times 10^{-6}$, where the uncertainties are statistical, systematic and from the ratio of fragmentation fractions $f_d/f_s$ which accounts for the different production rate of $B^0$ and $B_s^0$ mesons. The significance of $B_s^0 \rightarrow \phi \bar{K}^{*0}$ signal is 6.1 standard deviations. The fraction of longitudinal polarization in $B_s^0 \rightarrow \phi \bar{K}^{*0}$ decays is found to be $f_0 = 0.51 \pm 0.15 (stat) \pm 0.07 (syst)$

Search for CP violation in D+ -&gt; phi pi+ and Ds+ -&gt; Ks pi+ decays

A search for CP violation in D+ -&gt; phi pi+ decays is performed using data collected in 2011 by the LHCb experiment corresponding to an integrated luminosity of 1.0 fb^{-1} at a centre of mass energy of 7 TeV. The CP-violating asymmetry is measured to be (-0.04+/-0.14+/-0.14)% for candidates with K-K+ mass within 20 MeV/c^{2} of the phi meson mass. A search for a CP-violating asymmetry that varies across the phi mass region of the D+ -&gt; K-K+pi+ Dalitz plot is also performed, and no evidence for CP violation is found. In addition, the CP asymmetry in the Ds+ -&gt; Ks pi+ decay is measured to be (0.61+/-0.83+/-0.14)%

First observation of Bs -&gt; D_{s2}^{*+} X mu nu decays

Using data collected with the LHCb detector in proton-proton collisions at a centre-of-mass energy of 7 TeV, the semileptonic decays Bs -&gt; Ds+ X mu nu and Bs -&gt; D0 K+ X mu nu are detected. Two structures are observed in the D0 K+ mass spectrum at masses consistent with the known D^+_{s1}(2536) and $D^{*+}_{s2}(2573) mesons. The measured branching fractions relative to the total Bs semileptonic rate are B(Bs -&gt; D_{s2}^{*+} X mu nu)/B(Bs -&gt; X mu nu)= (3.3\pm 1.0\pm 0.4)%, and B(Bs -&gt; D_{s1}^+ X munu)/B(Bs -&gt; X mu nu)= (5.4\pm 1.2\pm 0.5)%, where the first uncertainty is statistical and the second is systematic. This is the first observation of the D_{s2}^{*+} state in Bs decays; we also measure its mass and width

Precision measurement of the B[0 over s]–[– over B][0 over s] oscillation frequency with the decay B[0 over s]→D[– over s]π[superscript +]

A key ingredient to searches for physics beyond the Standard Model in B[0 over s] mixing phenomena is the measurement of the B[0 over s]–[– over B][0 over s] oscillation frequency, which is equivalent to the mass difference Δm[subscript s] of the B[0 over s] mass eigenstates. Using the world's largest B[0 over s] meson sample accumulated in a dataset, corresponding to an integrated luminosity of 1.0 fb[superscript −1], collected by the LHCb experiment at the CERN LHC in 2011, a measurement of Δm[subscript s] is presented. A total of about 34 000 B[0 over s] → D[− over s]π[superscript +] signal decays are reconstructed, with an average decay time resolution of 44 fs. The oscillation frequency is measured to be Δm[subscript s] = 17.768 ± 0.023 (stat) ± 0.006 (syst) ps[superscript −1], which is the most precise measurement to date.National Science Foundation (U.S.

Measurement of the relative rate of prompt χc0χ_{c0}, χc1χ_{c1} and χc2χ_{c2} production at s=7\sqrt{s}=7TeV

Prompt production of charmonium $\chi_{c0}$, $\chi_{c1} and$\chi_{c2}$mesons is studied using proton-proton collisions at the LHC at a centre-of-mass energy of$\sqrt{s}=7$TeV. The$\chi_{c}$mesons are identified through their decay to$J/\psi\gamma$, with$J/\psi\to\mu^+\mu^-$using photons that converted in the detector. A data sample, corresponding to an integrated luminosity of$1.0\mathrm{fb}^{-1}$collected by the LHCb detector, is used to measure the relative prompt production rate of$\chi_{c1}$and$\chi_{c2}$in the rapidity range$2.

Measurement of Upsilon production in pp collisions at sqrt{s}=2.76 TeV

The production of Upsilon(1S), Upsilon(2S) and Upsilon(3S) mesons decaying into the dimuon final state is studied with the LHCb detector using a data sample corresponding to an integrated luminosity of 3.3 pb^{-1} collected in proton-proton collisions at a centre-of-mass energy of sqrt{s}=2.76 TeV. The differential production cross-sections times dimuon branching fractions are measured as functions of the Upsilon transverse momentum and rapidity, over the ranges p_T&lt;15 GeV/c and 2.0 Upsilon(1S) X) x B(Upsilon(1S) -&gt; mu+mu-) = 1.111 +/- 0.043 +/- 0.044 nb, sigma(pp -&gt; Upsilon(2S) X) x B(Upsilon(2S) -&gt; mu+mu-) = 0.264 +/- 0.023 +/- 0.011 nb, sigma(pp -&gt; Upsilon(3S) X) x B(Upsilon(3S) -&gt; mu+mu-) = 0.159 +/- 0.020 +/- 0.007 nb, where the first uncertainty is statistical and the second systematic.</y<4.5.

Study of beauty hadron decays into pairs of charm hadrons

First observations of the decays $\Lambda_b^0 \to \Lambda_c^+ D_{(s)}^-$ are reported using data corresponding to an integrated luminosity of $3\,{\rm fb}^{-1}$ collected at 7 and 8 TeV center-of-mass energy in proton-proton collisions with the LHCb detector. In addition, the most precise measurement of the branching fraction ${\mathcal{B}(B_s^0 \to D^+D_s^-)}$ is made and a search is performed for the decays $B^0_{(s)} \to \Lambda_c^+ \Lambda_c^-$. The results obtained are \begin{eqnarray*} \mathcal{B}(\Lambda_b^0 \to \Lambda_c^+ D^-)/\mathcal{B}(\Lambda_b^0 \to \Lambda_c^+ D_{s}^-) and=and 0.042 \pm 0.003({\rm stat}) \pm 0.003({\rm syst}), \left[\frac{\mathcal{B}(\Lambda_b^0 \to \Lambda_c^+ D_{s}^-)}{\mathcal{B}({\kern 0.2em}\overline{\kern -0.2em B}_d^0 \to D^+D_s^-)}\right]\big/\left[\frac{\mathcal{B}(\Lambda_b^0 \to \Lambda_c^+\pi^-)}{\mathcal{B}({\kern 0.2em}\overline{\kern -0.2em B}_d^0 \to D^+\pi^-)}\right] and=and 0.96 \pm 0.02({\rm stat}) \pm 0.06({\rm syst}), \mathcal{B}(B_s^0 \to D^+D_s^-)/\mathcal{B}({\kern 0.2em}\overline{\kern -0.2em B}_d^0 \to D^+D_s^-) and=and 0.038\pm0.004({\rm stat})\pm0.003({\rm syst}), \mathcal{B}({\kern 0.2em}\overline{\kern -0.2em B}^0 \to \Lambda_c^+ \Lambda_c^-)/\mathcal{B}({\kern 0.2em}\overline{\kern -0.2em B}_d^0 \to D^+D_s^-) and &lt; and 0.0022\; [95\% \; {\rm C.L.}], \mathcal{B}(B^0_{s} \to \Lambda_c^+ \Lambda_c^-)/\mathcal{B}(B_s^0 \to D^+D_s^-) and &lt; and 0.30\; [95\% \; {\rm C.L.}]. \end{eqnarray*} Measurement of the mass of the $\Lambda_b^0$ baryon relative to the $B^0$ meson gives ${M(\Lambda_b^0) -M(B^0) = 339.72\pm 0.24({\rm stat}) \pm 0.18({\rm syst})}$ MeV$/c^2$. This result provides the most precise measurement of the mass of the $\Lambda_b^0$ baryon to date