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LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., et al. (2018). Test of lepton flavor universality by the measurement of the B-0 -> D*(-) tau(+) nu(tau) branching fraction using three-prong tau decays. Phys. Rev. D, 97(7), 072013–26pp.
Abstract: The ratio of branching fractions R(D*(-)) = B(B-0 -> D*(-) tau(+)nu(tau))/(B-0 -> D*(-) mu(+)nu(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). The tau lepton is reconstructed with three charged pions in the final state. A novel method is used that exploits the different vertex topologies of signal and backgrounds to isolate samples of semitauonic decays of b hadrons with high purity. Using the B-0 -> D*(-) pi(+)pi(-)pi(+) decay as the normalization channel, the ratio B(B-0 -> D*(-) tau(+)nu(tau))/B(B-0 -> D* pi(+)pi(-)pi(+)) is measured to be 1.97 +/- 0.13 +/- 0.18, where the first uncertainty is statistical and the second systematic. An average of branching fraction measurements for the normalization channel is used to derive B(B-0 -> D*(-) tau(+)nu(tau))(_)= (1.42 +/- 0.094 +/- 0.129 +/- 0.054)%, where the third uncertainty is due to the limited knowledge of B(B-0 -> D*(-) pi(+)pi(-)pi(+)). A test of lepton flavor universality is performed using the well- measured branching fraction B(B-0 -> D*(-) mu(+)nu(mu)) to compute R(D*(-))0 = 0.291 +/- 0.019 +/- 0.026 +/- 0.013, where the third uncertainty originates from the uncertainties on B(B-0 -> D*(-) pi(+)pi(-)pi(+)) and B(B-0 -> D*(-) mu(+)nu(mu)) This measurement is in agreement with the Standard Model prediction and with previous measurements.
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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.
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LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., et al. (2018). Search for the rare decay Lambda(+)(c) -> p mu(+ )mu(-). Phys. Rev. D, 97(9), 091101–10pp.
Abstract: A search for the flavor-changing neutral-current decay Lambda(+)(c) -> p mu(+)mu(-) is reported using a data set corresponding to an integrated luminosity of 3.0 fb(-1) collected by the LHCb Collaboration. No significant signal is observed outside of the dimuon mass regions around the phi and omega resonances, and an upper limit is placed on the branching fraction of B(Lambda(+ )(c)-> p mu(+)mu(-)) < 7.7(9.6) x 10(-8) at 90%(95%) confidence level. A significant signal is observed in the omega dimuon mass region for the first time.
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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.
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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.
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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.
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LHCb Collaboration, Garcia Martin, L. M., Henry, L., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., et al. (2018). Observation of a New Xi(-)(b) Resonance. Phys. Rev. Lett., 121(7), 072002–12pp.
Abstract: From samples of pp collision data collected by the LHCb experiment at root s = 7, 8 and 13 TeV, corresponding to integrated luminosities of 1.0, 2.0 and 1.5 fb(-1), respectively, a peak in both the Lambda(0)(b) K- and Xi(0)(b)pi(-) invariant mass spectra is observed. In the quark model, radially and orbitally excited Xi(-)(b) resonances with quark content bds are expected. Referring to this peak as Xi(b)(6227)(-), the mass and natural width are measured to be m(Xi b(6227))(-) = 6226.9 +/- 2.0 +/- 0.3 +/- 0.2 MeV/c(2) and Gamma(Xi b(6227))- = 18.1 +/- 5.4 +/- 1.8 MeV/c(2), where the first uncertainty is statistical, the second is systematic, and the third, on m(Xi b(6227))(-), is due to the knowledge of the Lambda(0)(b) baryon mass. Relative production rates of the Xi(b)(6227)(-) -> Lambda K-0(b)- and Xi(b)(6227)(-) -> Xi(0)(b)pi(-) decays are also reported.
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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 Angular and CP Asymmetries in D-0 -> pi(+) pi(-) mu(+) mu(-) and D-0 -> K+ K- mu(+) mu(-) Decays. Phys. Rev. Lett., 121(9), 091801–10pp.
Abstract: The first measurements of the forward-backward asymmetry of the dimuon pair (A(FB)), the triple-product asymmetry (A(2 phi)), and the charge-parity-conjugation asymmetry (A(CP)), in D-0 -> pi(+) pi(-) mu(+) mu(-) and -> D-0 -> K+ K- mu(+) mu(-) decays are reported. They are performed using data from proton-proton collisions collected with the LHCb experiment from 2011 to 2016, corresponding to a total integrated luminosity of 5 fb(-1). The asymmetries are measured to be A(FB) (D-0 -> pi(+) pi(-) mu(+) mu(-)) = (3.3 +/- 3.7 +/- 0.6)%, A(2 phi) (D-0 -> pi(+) pi(-) mu(+) mu(-)) = (-0.6 +/- 3.7 +/- 0.6)%, A(CP) (D-0 -> pi(+) pi(-) mu(+) mu(-)) = (4.9 +/- 3.8 +/- 0.7)%, A(FB) (D-0 -> K+ K- mu(+) mu(-)) = (0 +/- 11 +/- 2 +/-)%, A(2 phi) (D-0 -> K+ K- mu(+) mu(-)) = (9 +/- 11 +/- 1)%, A(CP) (D-0 -> K+ K- mu(+) mu(-)) = (0 +/- 11 +/- 2)% where the first uncertainty is statistical and the second systematic. The asymmetries are also measured as a function of the dimuon invariant mass. The results are consistent with the standard model predictions.
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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 CP asymmetries in two-body B-(s)(0)-meson decays to charged pions and kaons. Phys. Rev. D, 98(3), 032004–23pp.
Abstract: The time-dependent CP asymmetries in B-0 -> pi(+)pi(-) and B-(s)(0) -> K+K- decays are measured using a data sample of p p collisions corresponding to an integrated luminosity of 3.0 fb(-1), collected with the LHCb detector at center-of-mass energies of 7 and 8 TeV. The same data sample is used to measure the time-integrated CP asymmetries in B-0 -> K+pi(-) and B-(s)(0) -> pi K-+(-) decays. The results are C pi+pi- = -0.34 +/- 0.06 +/- 0.01, S pi+pi- = -0.63 +/- 0.05 +/- 0.01, CK+K- = 0.20 +/- 0.06 +/- 0.02, SK+K- = 0.18 +/- 0.06 +/- 0.02, A(K+K-)(Delta Gamma) = -0.79 +/- 0.07 +/- 0.10, A(CP)(B0) = -0.084 +/- 0.004 +/- 0.003, and A(CP)(B0s) = 0.213 +/- 0.015 +/- 0.007, where the first uncertainties are statistical and the second systematic. Evidence for CP violation is found in the B-s(0) -> K+K- decay for the first time.
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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 Omega(0)(c) Baryon Lifetime. Phys. Rev. Lett., 121(9), 092003–10pp.
Abstract: We report a measurement of the lifetime of the Omega(0)(c) baryon using proton-proton collision data at center-of-mass energies of 7 and 8 TeV, corresponding to an integrated luminosity of 3.0 fb(-1) collected by the LHCb experiment. The sample consists of about 1000 Omega(-)(b) -> Omega(0)(c)mu(-)nu X-mu signal decays, where the Omega(0)(c) baryon is detected in the pK(-)K(-)pi(+) thorn final state and X represents possible additional undetected particles in the decay. The Omega(0)(c) lifetime is measured to be tau(Omega c0) = 268 +/- 24 +/- 10 +/- 2 fs, where the uncertainties are statistical, systematic, and from the uncertainty in the D+ lifetime, respectively. This value is nearly four times larger than, and inconsistent with, the current world-average value.
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