A search for the rare two-body charmless baryonic decay $B^+ \to p \bar\Lambda$ is performed with $pp$ collision data, corresponding to an integrated luminosity of $3\mbox{\,fb}^{-1}$, collected by ...the LHCb experiment at centre-of-mass energies of 7 and 8 TeV. An excess of $B^+ \to p \bar\Lambda$ candidates with respect to background expectations is seen with a statistical significance of 4.1 standard deviations, and constitutes the first evidence for this decay. The branching fraction, measured using the $B^+ \to K^0_{\mathrm S} \pi^+$ decay for normalisation, is \begin{eqnarray} \mathcal{B}(B^+ \to p \bar\Lambda) & = & ( 2.4 \,^{+1.0}_{-0.8} \pm 0.3 ) \times 10^{-7} \,, \nonumber \end{eqnarray} where the first uncertainty is statistical and the second systematic.
The $B_s^0\pi^\pm$ invariant mass distribution is investigated in order to search for possible exotic meson states. The analysis is based on a data sample recorded with the LHCb detector ...corresponding to $3$ fb$^{-1}$ of $pp$ collision data at $\sqrt{s} = 7$ and $8$ TeV. No significant excess is found, and upper limits are set on the production rate of the claimed $X(5568)$ state. Upper limits are also set as a function of the mass and width of a possible exotic meson decaying to the $B_s^0\pi^\pm$ final state.
(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image).A measurement of the differential branching fraction of the decay B super(0) arrow right K super()(892) super(0) mu ...super(+) mu super(-) is presented together with a determination of the S-wave fraction of the K super(+) pi super(-) system in the decay B super(0) arrow right K super(+) pi super(-) mu super(+) mu super(-). The analysis is based on pp-collision data corresponding to an integrated luminosity of 3 fb super(-1) collected with the LHCb experiment. The measurements are made in bins of the invariant mass squared of the dimuon system, q super(2). Precise theoretical predictions for the differential branching fraction of B super(0) arrow right K super()(892) super(0) mu super(+) mu super(-) decays are available for the q super(2) region 1.1 < q super(2) < 6.0 GeV super(2) /c super(4). In this q super(2) region, for the K super(+) pi super(-) invariant mass range 796 < m sub(K pi ) < 996 MeV/c super(2), the S-wave fraction of the K super(+) pi super(-) system in B super(0) arrow right K super(+) pi super(-) mu super(+) mu super(-) decays is found to be ... ... and the differential branching fraction of B super(0) arrow right K super()(892) super(0) mu super(+) mu super(-) decays is determined to be ... ... The differential branching fraction measurements presented are the most precise to date and are found to be in agreement with Standard Model predictions. Figure not available: see fulltext.
(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image).A model-dependent amplitude analysis of the decay B super(0) arrow right D(K sub(S) super(0) pi super(+) pi super(-))K ...super(0) is performed using proton-proton collision data corresponding to an integrated luminosity of 3.0 fb super(-1), recorded at ... and 8 TeV by the LHCb experiment. The CP violation observables x sub( plus or minus ) and y sub( plus or minus ), sensitive to the CKM angle gamma , are measured to be ... ... where the first uncertainties are statistical, the second systematic and the third arise from the uncertainty on the D arrow right K sub(S) super(0) pi super(+) pi super(-) amplitude model. These are the most precise measurements of these observables. They correspond to gamma =(80 sub(-22) super(+21)) degree and ..., where ... is the magnitude of the ratio of the suppressed and favoured B super(0) arrow right DK super(+) pi super(-) decay amplitudes, in a K pi mass region of plus or minus 50 MeV around the K super(*)(892) super(0) mass and for an absolute value of the cosine of the K super(*0) decay angle larger than 0.4. Figure not available: see fulltext.
(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image).A binned Dalitz plot analysis of the decays B super(0) arrow right DK super(0), with D arrow right K sub(S) super(0) pi ...super(+) pi super(-) and D arrow right K sub(S) super(0) K super(+) K super(-), is performed to measure the observables x sub( plus or minus ) and y sub( plus or minus ), which are related to the CKM angle gamma and the hadronic parameters of the decays. The D decay strong phase variation over the Dalitz plot is taken from measurements performed at the CLEO-c experiment, making the analysis independent of the D decay model. With a sample of proton-proton collision data, corresponding to an integrated luminosity of 3.0 fb super(-1), collected by the LHCb experiment, the values of the CP violation parameters are found to be x sub(+) = 0.05 plus or minus 0.35 plus or minus 0.02, x sub(-) = -0.31 plus or minus 0.20 plus or minus 0.04, y sub(+) = -0.81 plus or minus 0.28 plus or minus 0.06 and y sub(-) = 0.31 plus or minus 0.21 plus or minus 0.05, where the first uncertainties are statistical and the second systematic. These observables correspond to values gamma = (71 plus or minus 20) degree , ... and ... The parameters ... and ... are the magnitude ratio and strong phase difference between the suppressed and favoured B super(0) decay amplitudes, and have been measured in a region of plus or minus 50 MeV/c super(2) around the K super()(892) super(0) mass and with the magnitude of the cosine of the K super()(892) super(0) helicity angle larger than 0.4. Figure not available: see fulltext.
(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image).The decays Lambda sub(b) super(0) arrow right psi (2S)pK super(-) and Lambda sub(b) super(0) arrow right J/ psi pi super(+) ...pi super(-)pK super(-) are observed in a data sample corresponding to an integrated luminosity of 3 fb super(-1), collected in proton-proton collisions at 7 and 8 TeV centre-of-mass energies by the LHCb detector. The psi (2S) mesons are reconstructed through the decay modes psi (2S) arrow right mu super(+) mu super(-) and psi (2S) arrow right J/ psi pi super(+) pi super(-). The branching fractions relative to that of Lambda sub(b) super(0) arrow right J/ psi pK super(-) are measured to be ... ... where the first uncertainties are statistical, the second are systematic and the third is related to the knowledge of J/ psi and psi (2S) branching fractions. The mass of the Lambda sub(b) super(0) baryon is measured to be ... ... where the uncertainties are statistical and systematic. Figure not available: see fulltext.
A search is performed for the charmless three-body decays of the Lambda sub( )b super(0) and Xi sub( )b super(0) baryons to the final states Lambda h super(+) h' super(-), where h super(()' super()) ...= pi or K. The analysis is based on a data sample, corresponding to an integrated luminosity of 3 fb super(-1) of pp collisions, collected by the LHCb experiment. The Lambda sub( )b super(0) arrow right Lambda K super(+) pi super(-) and Lambda sub( )b super(0) arrow right Lambda K super(+) K super(-) decays are observed for the first time and their branching fractions and CP asymmetry parameters are measured. Evidence is seen for the Lambda sub( )b super(0) arrow right Lambda pi super(+) pi super(-) decay and limits are set on the branching fractions of Xi sub( )b super(0) baryon decays to the Lambda h super(+) h' super(-) final states. Figure not available: see fulltext.
The production of W and Z bosons in association with jets is studied in the forward region of proton-proton collisions collected at a centre-of-mass energy of 8 TeV by the LHCb experiment, ...corresponding to an integrated luminosity of 1.98 plus or minus 0.02 fb super(-1). The W boson is identified using its decay to a muon and a neutrino, while the Z boson is identified through its decay to a muon pair. Total cross-sections are measured and combined into charge ratios, asymmetries, and ratios of W +jet and Z+jet production cross-sections. Differential measurements are also performed as a function of both boson and jet kinematic variables. All results are in agreement with Standard Model predictions. Figure not available: see fulltext.
(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image).We perform a search for near-threshold Xi sub(b) super(0) resonances decaying to Xi sub(b) super(-) pi super(+) in a sample ...of proton-proton collision data corresponding to an integrated luminosity of 3 fb super(-1) collected by the LHCb experiment. We observe one resonant state, with the following properties: ... ... This confirms the previous observation by the CMS collaboration. The state is consistent with the J super(P)=3/2 super(+) Xi sub(b) super(0) resonance expected in the quark model. This is the most precise determination of the mass and the first measurement of the natural width of this state. We have also measured the ratio ... ...Figure not available: see fulltext.
(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image).The production of psi (2S) mesons is studied in dimuon final states using proton-lead (pPb) collision data collected by the ...LHCb detector. The data sample corresponds to an integrated luminosity of 1.6 nb super(-1). The nucleon-nucleon centre-of-mass energy of the pPb collisions is ... TeV. The measurement is performed using psi (2S) mesons with transverse momentum less than 14 GeV/c and rapidity y in the ranges 1.5 < y < 4.0 and -5.0 < y < -2.5 in the nucleon-nucleon centre-of-mass system. The forward-backward production ratio and the nuclear modification factor are determined for psi (2S) mesons. Using the production cross-section results of psi (2S) and J/ psi mesons from b-hadron decays, the ... cross-section in pPb collisions at ... TeV is obtained. Figure not available: see fulltext.
PDF
