LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., & Ruiz Valls, P. (2014). Measurement of charged particle multiplicities and densities in pp collisions root s=7 TeV in the forward region. Eur. Phys. J. C, 74(5), 2888–17pp.
Abstract: Charged particle multiplicities are studied in proton-proton collisions in the forward region at a centre-of-mass energy of TeV with data collected by the LHCb detector. The forward spectrometer allows access to a kinematic range of in pseudorapidity, momenta greater than and transverse momenta greater than . The measurements are performed using events with at least one charged particle in the kinematic acceptance. The results are presented as functions of pseudorapidity and transverse momentum and are compared to predictions from several Monte Carlo event generators.
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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Ruiz Valls, P., & Sanchez Mayordomo, C. (2014). Measurement of polarization amplitudes and CP asymmetries in B-0 -> phi K*(892)(0). J. High Energy Phys., 05(5), 069–24pp.
Abstract: An angular analysis of the decay B (0) -> phi K (*)(892)(0) is reported based on a pp collision data sample, corresponding to an integrated luminosity of 1.0 fb(-1), collected at a centre-of-mass energy of root S = 7 TeV with the LHCb detector. The P-wave amplitudes and phases are measured with a greater precision than by previous experiments, and confirm about equal amounts of longitudinal and transverse polarization. The S-wave K+ pi(-) and K+ K- contributions are taken into account and found to be significant. A comparison of the B (0) -> phi K (*)(892)(0) and results shows no evidence for direct CP violation in the rate asymmetry, in the triple-product asymmetries or in the polarization amplitudes and phases.
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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Ruiz Valls, P., & Sanchez Mayordomo, C. (2014). Angular analysis of charged and neutral B -> K mu(+) mu(-) decays. J. High Energy Phys., 05(5), 082–25pp.
Abstract: The angular distributions of the rare decays B+ -> K+mu(+)mu(-) and B-0 -> K-S(0)mu(+)mu(-) are studied with data corresponding to 3 fb(-1) of integrated luminosity, collected in proton-proton collisions at 7 and 8 TeV centre-of-mass energies with the LHCb detector. The angular distribution is described by two parameters, F-H and the forward-backward asymmetry of the dimuon system A(FB), which are determined in bins of the dimuon mass squared. The parameter F-H is a measure of the contribution from (pseudo)scalar and tensor amplitudes to the decay width. The measurements of A(FB) and F-H reported here are the most precise to date and are compatible with predictions from the Standard Model.
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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., & Ruiz Valls, P. (2014). Evidence for the decay B-c(+) -> J/psi 3 pi(+)2 pi(-). J. High Energy Phys., 05(5), 148–17pp.
Abstract: Evidence is presented for the decay B-c(+) -> J/psi 3 pi(+)2 pi(-) using proton-proton collision data, corresponding to an integrated luminosity of 3 fb(-1), collected with the LHCb detector. A signal yield of 32 +/- 8 decays is found with a significance of 4.5 standard deviations. The ratio of the branching fraction of the B-c(+) -> J/psi 3 pi(+)2 pi(-) decay to that of the B-c(+) -> J/psi pi(+) decay is measured to be B(B-c(+) -> J/psi 3 pi(+)2 pi(-))/B(B-c(+) -> J/psi pi(+)) = 1.74 +/- 0.44 +/- 0.24, where the first uncertainty is statistical and the second is systematic.
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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Ruiz Valls, P., & Sanchez Mayordomo, C. (2014). Measurement of psi (2S) polarisation in pp collisions at root s=7 TeV. Eur. Phys. J. C, 74(5), 2872–12pp.
Abstract: The polarisation of prompt mesons is measured by performing an angular analysis of decays using proton-proton collision data, corresponding to an integrated luminosity of 1.0, collected by the LHCb detector at a centre-of-mass energy of 7 TeV. The polarisation is measured in bins of transverse momentum and rapidity in the kinematic region and , and is compared to theoretical models. No significant polarisation is observed.
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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Ruiz Valls, P., & Sanchez Mayordomo, C. (2014). Measurement of CP violation in B-s(0) ->Phi Phi decays. Phys. Rev. D, 90(5), 052011–17pp.
Abstract: A measurement of the decay time-dependent CP-violating asymmetry in B-s(0) -> phi phi decays is presented, along with measurements of the T-odd triple-product asymmetries. In this decay channel, the CP-violating weak phase arises from the interference between B-s(0) -(B) over bar (0)(s) mixing and the loop-induced decay amplitude. Using a sample of proton-proton collision data corresponding to an integrated luminosity of 3.0 fb(-1) collected with the LHCb detector, a signal yield of approximately 4000 B-s(0) -> phi phi decays is obtained. The CP-violating phase is measured to be phi(s) = -0.17 +/- 0.15(stat) +/- 0.03(syst) rad. The triple-product asymmetries are measured to be A(U) = -0.003 +/- 0.017(stat) +/- 0.006(syst) and A(V) = -0.017 +/- 0.017(stat) +/- 0.006(syst). Results are consistent with the hypothesis of CP conservation.
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., Oyanguren, A., & Villanueva-Perez, P. (2014). Measurement of Collins asymmetries in inclusive production of charged pion pairs in e(+)e(-) annihilation at BABAR. Phys. Rev. D, 90(5), 052003–26pp.
Abstract: We present measurements of Collins asymmetries in the inclusive process e(+)e(-) -> pi pi X, where p stands for charged pions, at a center-of-mass energy of 10.6 GeV. We use a data sample of 468 fb(-1) collected by the BABAR experiment at the PEP-II B factory at SLAC, and consider pairs of charged pions produced in opposite hemispheres of hadronic events. We observe clear asymmetries in the distributions of the azimuthal angles in two distinct reference frames. We study the dependence of the asymmetry on several kinematic variables, finding that it increases with increasing pion momentum and momentum transverse to the analysis axis, and with increasing angle between the thrust and beam axis.
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., Oyanguren, A., & Villanueva-Perez, P. (2015). Dalitz plot analyses of B-0 -> (D-DK+)-K-0 and B+-> (D)over-bar(-)D(0)K(+) decays. Phys. Rev. D, 91(5), 052002–14pp.
Abstract: We present Dalitz plot analyses for the decays of B mesons to (D-DK+)-K-0 and (D) over bar (DK+)-D-0-K-0. We report the observation of the D*(s1)(2700)(+) resonance in these two channels and obtain measurements of the mass M(D*(s1)(2700)(+)) = 2699(-7)(+14) MeV/c(2) and of the width Gamma(D*(s1)(2700)(+)) = 127(-19)(+24) MeV, including statistical and systematic uncertainties. In addition, we observe an enhancement in the (DK+)-K-0 invariant mass around 2350-2500 MeV/c(2) in both decays B-0 -> (D-DK+)-K-0 and B+ -> (D) over bar (DK+)-D-0-K-0, which we are not able to interpret. The results are based on 429 fb(-1) of data containing 471 x 10(6) B (B) over bar pairs collected at the Upsilon(4S) resonance with the BABAR detector at the SLAC National Accelerator Laboratory.
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., Oyanguren, A., & Villanueva-Perez, P. (2015). Measurement of the D-0 -> pi(-)e(+)nu(e) differential decay branching fraction as a function of q(2) and study of form factor parametrizations. Phys. Rev. D, 91(5), 052022–25pp.
Abstract: Based on a sample of 500 million e(+)e(-) -> c (c) over bar events recorded by the BABAR detector at c. m. energies of close to 10.6 GeV, we report on a study of the decay D0 ->pi(-)e(+)nu(e). We measure the ratio of branching fractions, R-D = B(D-0 -> pi(-)e(+)nu(e))/beta(D-0 -> K-pi(+)) = 0.0713 +/- 0.0017(stat) +/- 0.0024(syst), and use the present world average for B(D-0 -> K-pi(+)) to obtain B(D-0 -> pi(-)e(+)nu e) = (2.770 +/- 0.068(stat) +/- 0.092(syst) +/- 0.037(ext)) x 10(-3) where the third error accounts for the uncertainty on the branching fraction for the reference channel. The measured dependence of the differential branching fraction on q(2), the four-momentum transfer squared between the D and the pi meson, is compared to various theoretical predictions for the hadronic form factor, f(+,D)(pi)(q(2)), and the normalization vertical bar V-cd vertical bar x f(+,D)(pi)(q(2) = 0) = 0.1374 +/- 0.0038(stat) +/- 0.0022(sys)t +/- 0.0009(ext). is extracted from a fit to data. Using the most recent LQCD prediction of f(+,D)(pi)(q(2) = 0) = 0.666 +/- 0.029, we obtain vertical bar V-cd vertical bar = 0.206 +/- 0.007(exp) +/- 0.009(LQCD). Assuming, instead, vertical bar V-cd vertical bar = vertical bar V-us vertical bar = 0.2252 +/- 0.0009, we obtain f(+,D)(pi)(q(2) = 0) = 0.610 +/- 0.020(exp) +/- 0.005(ext). The q(2) dependence of f(+,D)(pi)(q(2)) is compared to a variety of multipole parametrizations. This information is applied to B-0 -> pi(-)e(+)nu(e) decays and, combined with an earlier B-0 -> pi(-)e(+)nu(e) measurement by BABAR, is used to derive estimates of vertical bar V-ub vertical bar.
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., Oyanguren, A., & Villanueva-Perez, P. (2015). Measurement of the branching fractions of the radiative leptonic tau decays tau -> e gamma v(v)over-bar and tau -> μgamma v(v)over-bar at BABAR. Phys. Rev. D, 91(5), 051103–8pp.
Abstract: We perform a measurement of the tau -> l gamma v (v) over bar (l = e, mu) branching fractions for a minimum photon energy of 10 MeV in the tau rest frame, using 431 fb(-1) of e(+) e(-) collisions collected at the center-of-mass energy of the Upsilon(4S) resonance with the BABAR detector at the PEP-II storage rings. We find B(tau -> μgamma v (v) over bar = (3.69 +/- 0.03 +/- 0.10) x 10(-3) and B(tau -> e gamma v (v) over bar = (1.847 +/- 0.015 +/- 0.052) x 10(-2), where the first quoted error is statistical and the second is systematic. These results are substantially more precise than previous measurements.
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