A study of CP violation in B-+/- -> DK +/- and B-+/- -> D pi(+/-) decays with D -> (KSK +/-)-K-0 pi(-/+) final states

A first study of CP violation in the decay modes $B^\pm\to [K^0_{\rm S} K^\pm \pi^\mp]_D h^\pm$ and $B^\pm\to [K^0_{\rm S} K^\mp \pi^\pm]_D h^\pm$, where $h$ labels a $K$ or $\pi$ meson and $D$ labels a $D^0$ or $\overline{D}^0$ meson, is performed. The analysis uses the LHCb data set collected in $pp$ collisions, corresponding to an integrated luminosity of 3 fb$^{-1}$. The analysis is sensitive to the CP-violating CKM phase $\gamma$ through seven observables: one charge asymmetry in each of the four modes and three ratios of the charge-integrated yields. The results are consistent with measurements of $\gamma$ using other decay modes

Measurement of Upsilon production in collisions at root 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_{\rm T} Upsilon(1S) X) x B(Upsilon(1S) -> mu+mu-) = 1.111 +/- 0.043 +/- 0.044 nb, sigma(pp -> Upsilon(2S) X) x B(Upsilon(2S) -> mu+mu-) = 0.264 +/- 0.023 +/- 0.011 nb, sigma(pp -> Upsilon(3S) X) x B(Upsilon(3S) -> mu+mu-) = 0.159 +/- 0.020 +/- 0.007 nb, where the first uncertainty is statistical and the second systematic

Study of forward Z + jet production in pp collisions at √s=7 TeV

A measurement of the $Z(\rightarrow\mu^+\mu^-)$+jet production cross-section in $pp$ collisions at a centre-of-mass energy $\sqrt{s} = 7$ TeV is presented. The analysis is based on an integrated luminosity of $1.0\,\text{fb}^{-1}$ recorded by the LHCb experiment. Results are shown with two jet transverse momentum thresholds, 10 and 20 GeV, for both the overall cross-section within the fiducial volume, and for six differential cross-section measurements. The fiducial volume requires that both the jet and the muons from the Z boson decay are produced in the forward direction ($2.0<\eta<4.5$). The results show good agreement with theoretical predictions at the second-order expansion in the coupling of the strong interaction.A measurement of the $Z(\rightarrow\mu^+\mu^-)$+jet production cross-section in $pp$ collisions at a centre-of-mass energy $\sqrt{s} = 7$ TeV is presented. The analysis is based on an integrated luminosity of $1.0\,\text{fb}^{-1}$ recorded by the LHCb experiment. Results are shown with two jet transverse momentum thresholds, 10 and 20 GeV, for both the overall cross-section within the fiducial volume, and for six differential cross-section measurements. The fiducial volume requires that both the jet and the muons from the Z boson decay are produced in the forward direction ($2.0<\eta<4.5$). The results show good agreement with theoretical predictions at the second-order expansion in the coupling of the strong interaction

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}^-) &=& 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] &=& 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^-) &=& 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^-) & < & 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^-) & < & 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

Observation of associated production of a ZZ boson with a DD meson in the forward region

A search for associated production of a $Z$ boson with an open charm meson is presented using a data sample, corresponding to an integrated luminosity of $1.0\mathrm{fb}^{-1}$ of proton--proton collisions at a centre-of-mass energy of 7 TeV, collected by the LHCb experiment. Seven candidate events for associated production of a $Z$ boson with a $D^0$ meson and four candidate events for a $Z$ boson with a $D^+$ meson are observed with a combined significance of 5.1 standard deviations. The production cross-sections in the forward region are measured to be $$\sigma_{Z\rightarrow\mu^+\mu^-\!,D^0} = 2.50\pm1.12\pm0.22pb$$ $$\sigma_{Z\rightarrow\mu^+\mu^-\!,D^+} = 0.44\pm0.23\pm0.03pb,$$ where the first uncertainty is statistical and the second systematic

Measurement of the resonant and CP components in B‾0→J/ψπ+π−\overline{B}^0\rightarrow J/\psi \pi^+\pi^- decays

The resonant structure of the reaction $\overline{B}^0\rightarrow J/\psi \pi^+\pi^-$ is studied using data from 3 fb$^{-1}$ of integrated luminosity collected by the LHCb experiment, one-third at 7 Tev center-of-mass energy and the remainder at 8 Tev. The invariant mass of the $\pi^+\pi^-$ pair and three decay angular distributions are used to determine the fractions of the resonant and non-resonant components. Six interfering $\pi^+\pi^-$ states: $\rho(770)$, $f_0(500)$, $f_2(1270)$, $\rho(1450)$, $\omega(782)$ and $\rho(1700)$ are required to give a good description of invariant mass spectra and decay angular distributions. The positive and negative CP fractions of each of the resonant final states are determined. The $f_0(980)$ meson is not seen and the upper limit on its presence, compared with the observed $f_0(500)$ rate, is inconsistent with a model of tetraquark substructure for these scalar mesons at the eight standard deviation level. In the $q\overline{q}$ model, the absolute value of the mixing angle between the $f_0(980)$ and the $f_0(500)$ scalar mesons is limited to be less than $17^{\circ}$ at 90 % confidence level

Updated measurements of exclusive J/ψJ/\psi and ψ(2S)\psi(2S) production cross-sections in pppp collisions at s=7\sqrt{s}=7 TeV

The differential cross-section as a function of rapidity has been measured for the exclusive production of $J/\psi$ and $\psi(2S)$ mesons in proton-proton collisions at $\sqrt{s}=7$ TeV, using data collected by the LHCb experiment, corresponding to an integrated luminosity of 930 pb$^{-1}$. The cross-sections times branching fractions to two muons having pseudorapidities between 2.0 and 4.5 are measured to be $$\begin{array}{rl} \sigma_{pp\rightarrow J/\psi\rightarrow{\mu^+}{\mu^-}}(2.0<\eta_{\mu^\pm }<4.5)=&291\pm 7\pm19 {\rm \ pb},\\ \sigma_{pp\rightarrow\psi(2S)\rightarrow{\mu^+}{\mu^-}}(2.0<\eta_{\mu^\pm}<4.5)=&6.5\pm 0.9\pm 0.4 {\rm \ pb},\end{array}$$ where the first uncertainty is statistical and the second is systematic. The measurements agree with next-to-leading order QCD predictions as well as with models that include saturation effects.The differential cross-section as a function of rapidity has been measured for the exclusive production of $J/\psi$ and $\psi(2S)$ mesons in proton-proton collisions at $\sqrt{s}=7$ TeV, using data collected by the LHCb experiment, corresponding to an integrated luminosity of 930 pb$^{-1}$. The cross-sections times branching fractions to two muons having pseudorapidities between 2.0 and 4.5 are measured to be $$\begin{array}{rl} \sigma_{pp\rightarrow J/\psi\rightarrow{\mu^+}{\mu^-}}(2.0<\eta_{\mu^\pm }<4.5)=&291\pm 7\pm19 {\rm \ pb},\\ \sigma_{pp\rightarrow\psi(2S)\rightarrow{\mu^+}{\mu^-}}(2.0<\eta_{\mu^\pm}<4.5)=&6.5\pm 0.9\pm 0.4 {\rm \ pb},\end{array}$$ where the first uncertainty is statistical and the second is systematic. The measurements agree with next-to-leading order QCD predictions as well as with models that include saturation effects.The differential cross-section as a function of rapidity has been measured for the exclusive production of $J/\psi$ and $\psi(2S)$ mesons in proton-proton collisions at $\sqrt{s}=7$ TeV, using data collected by the LHCb experiment, corresponding to an integrated luminosity of 930 pb$^{-1}$. The cross-sections times branching fractions to two muons having pseudorapidities between 2.0 and 4.5 are measured to be $$\begin{array}{rl} \sigma_{pp\rightarrow J/\psi\rightarrow{\mu^+}{\mu^-}}(2.0<\eta_{\mu^\pm }<4.5)=&291\pm 7\pm19 {\rm \ pb},\\ \sigma_{pp\rightarrow\psi(2S)\rightarrow{\mu^+}{\mu^-}}(2.0<\eta_{\mu^\pm}<4.5)=&6.5\pm 0.9\pm 0.4 {\rm \ pb},\end{array}$$ where the first uncertainty is statistical and the second is systematic. The measurements agree with next-to-leading order QCD predictions as well as with models that include saturation effects

Studies of beauty baryon decays to D0ph−D^0 ph^- and Λc+h−\Lambda_c^+ h^- final states

Decays of beauty baryons to the $D^0 p h^-$ and $\Lambda_c^+ h^-$ final states (where $h$ indicates a pion or a kaon) are studied using a data sample of $pp$ collisions, corresponding to an integrated luminosity of 1.0 fb$^{-1}$, collected by the LHCb detector. The Cabibbo-suppressed decays $\Lambda_b^0\to D^0 p K^-$ and $\Lambda_b^0\to \Lambda_c^+ K^-$ are observed and their branching fractions are measured with respect to the decays $\Lambda_b^0\to D^0 p \pi^-$ and $\Lambda_b^0\to \Lambda_c^+ \pi^-$. In addition, the first observation is reported of the decay of the neutral beauty-strange baryon $\Xi_b^0$ to the $D^0 p K^-$ final state, and a measurement of the $\Xi_b^0$ mass is performed. Evidence of the $\Xi_b^0\to \Lambda_c^+ K^-$ decay is also reported.Decays of beauty baryons to the D0ph− and Λc+h− final states (where h indicates a pion or a kaon) are studied using a data sample of pp collisions, corresponding to an integrated luminosity of 1.0  fb−1, collected by the LHCb detector. The Cabibbo-suppressed decays Λb0→D0pK− and Λb0→Λc+K− are observed, and their branching fractions are measured with respect to the decays Λb0→D0pπ− and Λb0→Λc+π−. In addition, the first observation is reported of the decay of the neutral beauty-strange baryon Ξb0 to the D0pK− final state, and a measurement of the Ξb0 mass is performed. Evidence of the Ξb0→Λc+K− decay is also reported.Decays of beauty baryons to the $D^0 p h^-$ and $\Lambda_c^+ h^-$ final states (where $h$ indicates a pion or a kaon) are studied using a data sample of $pp$ collisions, corresponding to an integrated luminosity of 1.0 fb$^{-1}$, collected by the LHCb detector. The Cabibbo-suppressed decays $\Lambda_b^0\to D^0 p K^-$ and $\Lambda_b^0\to \Lambda_c^+ K^-$ are observed and their branching fractions are measured with respect to the decays $\Lambda_b^0\to D^0 p \pi^-$ and $\Lambda_b^0\to \Lambda_c^+ \pi^-$. In addition, the first observation is reported of the decay of the neutral beauty-strange baryon $\Xi_b^0$ to the $D^0 p K^-$ final state, and a measurement of the $\Xi_b^0$ mass is performed. Evidence of the $\Xi_b^0\to \Lambda_c^+ K^-$ decay is also reported

Measurement of the Bc+B_c^+ meson lifetime using Bc+→J/ψμ+νμXB_c^+ \to J/\psi\mu^+ \nu_{\mu} X decays

The lifetime of the $B_c^+$ meson is measured using semileptonic decays having a $J/\psi$ meson and a muon in the final state. The data, corresponding to an integrated luminosity of $2\mathrm{~fb^{-1}}$, are collected by the LHCb detector in $pp$ collisions at a centre-of-mass energy of $8\,\mathrm{TeV}$. The measured lifetime is $$\tau = 509 \pm 8 \pm 12 \mathrm{~fs},$$ where the first uncertainty is statistical and the second is systematic.The lifetime of the $B_c^+$ meson is measured using semileptonic decays having a $J\!/\!\psi$ meson and a muon in the final state. The data, corresponding to an integrated luminosity of $2\mathrm{~fb^{-1}}$, are collected by the LHCb detector in $pp$ collisions at a centre-of-mass energy of $8\,\mathrm{TeV}$. The measured lifetime is $$\tau = 509 \pm 8 \pm 12 \mathrm{~fs},$$ where the first uncertainty is statistical and the second is systematic.The lifetime of the B c + meson is measured using semileptonic decays having a J / ψ meson and a muon in the final state. The data, corresponding to an integrated luminosity of 2 fb - 1 , are collected by the LHCb detector in p p collisions at a centre-of-mass energy of 8 TeV. The measured lifetime is τ = 509 ± 8 ± 12 fs , where the first uncertainty is statistical and the second is systematic