LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., et al. (2018). Measurement of the Ratio of Branching Fractions B(B-c(+) -> J/psi tau(+)nu(tau))/B(B-c(+) -> J/psi mu(+)nu(mu)). Phys. Rev. Lett., 120(12), 121801–10pp.
Abstract: A measurement is reported of the ratio of branching fractions R(J/psi) = B(B-c(+) -> J/psi tau(+)nu(tau))/B(B-c(+) -> J/psi mu(+)nu(mu)), where the tau(+) lepton is identified in the decay mode tthorn tau(+) -> mu(+)nu(mu)(nu) over bar (tau). This analysis uses a sample of proton-proton collision data corresponding to 3.0 fb(-1) of integrated luminosity recorded with the LHCb experiment at center-of-mass energies of 7 and 8 TeV. A signal is found for the decay B-c(+) -> J/psi tau(+)nu(tau) at a significance of 3 standard deviations corrected for systematic uncertainty, and the ratio of the branching fractions is measured to be R(J/psi) = 0.71 +/- 0.17(stat) +/- 0.18(syst). This result lies within 2 standard deviations above the range of central values currently predicted by the standard model.
|
LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., et al. (2018). Measurement of the Ratio of the B-0 -> D*(-)iota(+)v(iota) and B-0 -> D*(-) mu(+)v(mu) Branching Fractions Using Three-Prong tau-Lepton Decays. Phys. Rev. Lett., 120(17), 171802–11pp.
Abstract: The ratio of branching fractions R(D*(-)) equivalent to B(B-0 -> D*(-) iota(+)v(iota))/B(B-0 -> D*(-) mu+ v(mu)) is measured using a data sample of proton-proton collisions collected with the LHCb detector at center-of-mass energies of 7 and 8 TeV, corresponding to an integrated luminosity of 3 fb(-1). For the first time, R(D*-) is determined using the iota-lepton decays with three charged pions in the final state. The B-0 -> D*(-) iota+ v(iota) yield is normalized to that of the B-0 -> D*(-) pi(+) pi(-) pi(+) mode, providing a measurement B-0 -> D*(-) iota+ v(iota) / B(B-0 -> D*(-) pi(+) pi(-) pi(+)) = 1.97 +/- 0.13 +/- 0.18, where the first uncertainty is statistical and the second systematic. The value of (B-0 -> D*(-) iota+ v(iota)) = (1.42 +/- 0.094 +/- 0.129 +/- 0.054)% is obtained, where the third uncertainty is due to the limited knowledge of the branching fraction of the normalization mode. Using the well-measured branching fraction of the B-0 -> D*(-) mu+ v(mu) decay, a value of R(D*(-)) = 0.291 +/- 0.019 +/- 0.026 +/- 0.013 is established, where the third uncertainty is due to the limited knowledge of the branching fractions of the normalization and B-0 -> D*(-) mu+ v(mu) modes. This measurement is in agreement with the standard model prediction and with previous results.
|
LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., et al. (2018). Evidence for the Rare Decay Sigma(+) -> p mu(+)mu(-). Phys. Rev. Lett., 120(22), 221803–10pp.
Abstract: A search for the rare decay Sigma(+) -> p mu(+)mu(-) is performed using pp collision data recorded by the LHCb experiment at center-of-mass energies root s = 7 and 8 TeV, corresponding to an integrated luminosity of 3 fb(-1). An excess of events is observed with respect to the background expectation, with a signal significance of 4.1 standard deviations. No significant structure is observed in the dimuon invariant mass distribution, in contrast with a previous result from the HyperCP experiment. The measured Sigma(+) -> p mu(+)mu(-) branching fraction is (2.2(-1.3)(+1.8)) x 10(-8), where statistical and systematic uncertainties are included, which is consistent with the standard model prediction.
|
LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., et al. (2018). Amplitude Analysis of the Decay (B)over-bar(0 )-> K-S(0)pi(+)pi(- )and First Observation of the CP Asymmetry in (B)over-bar(0 )-> K* (892)(-)pi(+). Phys. Rev. Lett., 120(26), 261801–10pp.
Abstract: The time-integrated untagged Dalitz plot of the three-body hadronic charmless decay (B) over bar (0 )-> K-S(0)pi(+)pi(- ) is studied using a pp collision data sample recorded with the LHCb detector, corresponding to an integrated luminosity of 3.0 fb(-1). The decay amplitude is described with an isobar model. Relative contributions of the isobar amplitudes to the (B) over bar (0 )-> K-S(0)pi(+)pi(- ) decay branching fraction and CP asymmetries of the flavor-specific amplitudes are measured. The CP asymmetry between the conjugate (B) over bar (0 )-> K* (892)(-)pi(+) and (B) over bar (0 )-> K* (892)(-)pi(+) decay rates is determined to be -0.308 +/- 0.062.
|
LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., et al. (2018). Measurement of the Lifetime of the Doubly Charmed Baryon Xi(++)(cc). Phys. Rev. Lett., 121(5), 052002–10pp.
Abstract: The first measurement of the lifetime of the doubly charmed baryon Xi(++)(cc) is presented, with the signal reconstructed in the final state Lambda K-+(c)-pi(+)pi(+). The data sample used corresponds to an integrated luminosity of 1.7 fb(-1), collected by the LHCb experiment in proton-proton collisions at a center-of-mass energy of 13 TeV. The Xi(++)(cc) lifetime is measured to be 0.256(-0.022)(+0.024) (stat) +/- 0.014(syst) ps.
|
