LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., et al. (2018). Updated determination of D-0-(D)over-bar(0) mixing and CP violation parameters with D-0 -> K+ pi(-) decays. Phys. Rev. D, 97(3), 031101–11pp.
Abstract: We report measurements of charm-mixing parameters based on the decay-time-dependent ratio of D-0 -> K+pi(-) to D-0 -> K-pi(+) rates. The analysis uses a data sample of proton-proton collisions corresponding to an integrated luminosity of 5.0 fb(-1) recorded by the LHCb experiment from 2011 through 2016. Assuming charge-parity (CP) symmetry, the mixing parameters are determined to be x'(2) = (3.9 +/- 2.7) x 10(-5), y' = (5.28 +/- 0.52) x 10(-3), and R-D = (3.454 +/- 0.031) x 10(-3). Without this assumption, the measurement is performed separately for D-0 and (D) over bar (0) mesons, yielding a direct CP-violating asymmetry A(D) = (-0.1 +/- 9.1) x 10(-3), and magnitude of the ratio of mixing parameters 1.00 < vertical bar q/p vertical bar < 1.35 at the 68.3% confidence level. All results include statistical and systematic uncertainties and improve significantly upon previous single-measurement determinations. No evidence for CP violation in charm mixing is observed.
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LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., et al. (2020). Measurement of Xi(++)(cc) production in pp collisions at root s=13 TeV. Chin. Phys. C, 44(2), 022001–11pp.
Abstract: The production of Xi(++)(cc) baryons in proton-proton collisions at a centre-of-mass energy of root s = 13 Tev is measured in the transverse-momentum range 4 < p(T) < 15 GeV/c and the rapidity range 2.0 < y < 4.5. The data used in this measurement correspond to an integrated luminosity of 1.7 fb(-1), recorded by the LHCb experiment during 2016. The ratio of the Xi(++)(cc) production cross-section times the branching fraction of the Xi(++)(cc) -> Lambda K-+(c)-pi(+)pi(+) decay relative to the prompt Lambda(+)(c) production cross-section is found to be (2.22 +/- 0.27 +/- 0.29) x 10(-4), assuming the central value of the measured Xi(++)(cc) lifetime, where the first uncertainty is statistical and the second systematic.
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LHCb Collaboration(Aaij, R. et al), Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Rebollo De Miguel, M., Remon Alepuz, C., et al. (2023). Amplitude analysis of the Lambdac+ -> p K- pi+ decay and Lambdac+ baryon polarization measurement in semileptonic beauty hadron decays. Phys. Rev. D, 108(1), 012023–27pp.
Abstract: An amplitude analysis of A+c – pK- & pi;+ decays together with a measurement of the A+c polarization vector in semiOleptonic beauty hadron decays is presented. A sample of 400 000 candidates is selected from proton-proton collisions recorded by the LHCb detector at a center-of-mass energy of 13 TeV. An amplitude model is developed and the resonance fractions as well as two- and three-body decay parameters are reported. The mass and width of the Ao2000 thorn state are also determined. A significant A+c polarization is found. A large sensitivity of the A+c – pK-& pi;+ decay to the polarization is seen, making the amplitude model suitable for A+c polarization measurements in other systems.
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LHCb Collaboration(Aaij, R. et al), Jaimes Elles, S. J., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Rebollo De Miguel, M., et al. (2023). Search for the baryon- and lepton-number violating decays B0 → pμ- and Bs0 → pμ-. Phys. Rev. D, 108(1), 012021–15pp.
Abstract: A search for the baryon- and lepton-number violating decays B-0 -> p mu(-) and B-s(0) -> p mu(-) is performed at the LHCb experiment using data collected in proton-proton collisions at root s = 7, 8 and 13 TeV, corresponding to integrated luminosities of 1, 2, and 6 fb(-1), respectively. No significant signal for B-0 -> p mu(-) and B-s(0) -> p mu(-) decays is found and the upper limits on the branching fractions are determined to be B(B-0 -> p mu(-)) < 2.6(3.1) x 10(-9) and B(B-s(0) -> p mu(-)) < 12.1(14.0) x 10(-9), respectively, at 90% (95%) confidence level. These are the first limits on these decays to date.
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LHCb Collaboration(Aaij, R. et al), Jaimes Elles, S. J., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Rebollo De Miguel, M., et al. (2023). Study of the B- → Λc+(Λ)over-barc-K- decay. Phys. Rev. D, 108(1), 012020–15pp.
Abstract: The decay B- -> Lambda(+)(c)(Lambda) over bar K--(c)- is studied in proton-proton collisions at a center-of-mass energy of root s = 13 TeV using data corresponding to an integrated luminosity of 5 fb(-1) collected by the LHCb experiment. In the Lambda K-+(c)- system, the Xi(c)(2930)(0) state observed at the BABAR and Belle experiments is resolved into two narrower states, Xi(c)(2923)(0) and Xi(c)(2939)(0), whose masses and widths are measured to be m(Xi(c)(2930)(0) = 2924.5 +/- 0.4 +/- 1.1 Mev, m Xi(c)(2930)(0)) = 2938.5 +/- 0.9 +/- 2.3 Mev, Gamma(Xi(c)(2930)(0)) = 4.8 +/- 0.9 +/- 1.5 MeV, Gamma(Xi(c)(2930)(0) – 11.0 +/- 1.9 +/- 7.5 MeV, where the first uncertainties are statistical and the second systematic. The results are consistent with a previous LHCb measurement using a prompt Lambda K-+(c)- sample. Evidence of a new Xi(c)(2930)(0) state is found with a local significance of 3.8 sigma, whose mass and width are measured to be 2881.8 +/- 3.1 +/- 8.5 MeV and 12.4 +/- 5.3 +/- 5.8 MeV, respectively. In addition, evidence of a new decay mode Xi(c)(2930)(0) -> Lambda K-+(c) is found with a significance of 3.7 sigma. The relative branching fraction of B- -> Lambda(+)(c)(Lambda) over bar K--(c)- with respect to the B- -> D+D-K- decay is measured to be 2.36 +/- 0.11 +/- 0.22 +/- 0.25, where the first uncertainty is statistical, the second systematic and the third originates from the branching fractions of charm hadron decays.
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LHCb Collaboration(Aaij, R. et al), Jaimes Elles, S. J., Jashal, B. K., Martinez Vidal, F., Oyanguren, A., Rebollo De Miguel, M., et al. (2023). Test of lepton flavor universality using B0→D*−τ+ντ decays with hadronic τ channels. Phys. Rev. D, 108, 012018–18pp.
Abstract: The branching fraction B(B0→D*−τ+ντ) is measured relative to that of the normalization mode B0→D*−π+π−π+ using hadronic τ+→π+π−π+(π0)¯ντ decays in proton-proton collision data at a center-of-mass energy of 13 TeV collected by the LHCb experiment, corresponding to an integrated luminosity of 2 fb−1. The measured ratio is B(B0→D*−τ+ντ)/B(B0→D*−π+π−π+)=1.70±0.10+0.11−0.10, where the first uncertainty is statistical and the second is related to systematic effects. Using established branching fractions for the B0→D*−π+π−π+ and B0→D*−μ+νμ modes, the lepton universality test R(D*−)≡B(B0→D*−τ+ντ)/B(B0→D*−μ+νμ) is calculated, R(D*−)=0.247±0.015±0.015±0.012, where the third uncertainty is due to the uncertainties on the external branching fractions. This result is consistent with the Standard Model prediction and with previous measurements.
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LHCb Collaboration(Aaij, R. et al), Jaimes Elles, S. J., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Rebollo De Miguel, M., et al. (2023). Amplitude analysis of B0 -> D0bar Ds+ pi- and B+ -> D- Ds+ pi+ decays. Phys. Rev. D, 108(1), 012017–30pp.
Abstract: Resonant contributions in B0 & RARR; over bar D0D+s & pi;- and B+ & RARR; D-D+s & pi;+ decays are determined with an amplitude analysis, which is performed both separately and simultaneously, where in the latter case isospin symmetry between the decays is assumed. The analysis is based on data collected by the LHCb detector in proton-proton collisions at center-of-mass energies of 7, 8, and 13 TeV. The full data sample corresponds to an integrated luminosity of 9 fb-1. A doubly charged spin-0 open-charm tetraquark candidate together with a neutral partner, both with masses near 2.9 GeV, are observed in the Ds & pi; decay channel.
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LHCb Collaboration(Aaij, R. et al), Jaimes Elles, S. J., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Rebollo De Miguel, M., et al. (2023). Search for direct CP violation in charged charmless B → PV decays. Phys. Rev. D, 108(1), 012013–13pp.
Abstract: Measurements of CP asymmetry in charmless B -> PV decays are presented, where P and V denote a pseudoscalar and a vector meson, respectively. Five different B -> PV decays from four final states, B-+/- -> pi(+/-)pi(+) pi(-), B-+/- -> K-+/-pi(+) pi(-), B-+/-->(KK+K-)-K-+/- and B-+/- -> pi(K+K-)-K-+/- are analyzed. The measurements are based on a method that does not require full amplitude analyses, and are performed using proton-proton collision data at a center-of-mass energy of 13 TeV collected by LHCb between 2015 and 2018, corresponding to an integrated luminosity of 5.9 fb(-1). In the pi(+) pi(-) P-wave, in the region dominated by the B-+/- -> rho(770)K-0(+/-) decay, a CP asymmetry of A(CP) = +0.150 +/- 0.019 +/- 0.011 is measured, where the first uncertainty is statistical and the second is systematic. This is the first observation of CP violation in this process. For the other four decay channels, in regions dominated by the B-+/- -> rho(770)(0)pi(+/-), B-+/- -> K(-)*(892)(0) pi(+/-), B-+/- -> K(-)* (892)K-+/- and B-+/- -> (sic)(1020) K-+/- decays, CP asymmetries in the P-wave compatible with zero are measured.
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LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., et al. (2020). Measurement of the branching fraction of the decay B-s(0) -> (KSKS0)-K-0. Phys. Rev. D, 102(1), 012011–15pp.
Abstract: A measurement of the branching fraction of the decay B-s(0) -> (KSKS0)-K-0 is performed using proton- proton – collision data corresponding to an integrated luminosity of 5 fb(-1) collected by the LHCb experiment between 2011 and 2016. The branching fraction is determined to be B(B-s(0) -> (KSKS0)-K-0) = [8.3 +/- 1.6(stat) +/- 0.9(syst) +/- 0.8(norm) +/- 0.3(f(s)/f(d))] x 10(-6), where the first uncertainty is statistical, the second is systematic, and the third and fourth are due to uncertainties on the branching fraction of the normalization mode B-0 -> phi K(S)(0 )and the ratio of hadronization fractions f(s)/f(d). This is the most precise measurement of this branching fraction to date. Furthermore, a measurement of the branching fraction of the decay B-s(0) -> (KSKS0)-K-0 is performed relative to that of the B-s(0) -> (KSKS0)-K-0 channel, and is found to be B(B-s(0) -> (KSKS0)-K-0)/B(B-s(0) -> (KSKS0)-K-0) = [7.5 +/- 3.1(stat) 0.5(syst) +/- 0.3(f(s)/f(d))1 x 10(-2).
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LHCb Collaboration(Aaij, R. et al), Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., & Ruiz Vidal, J. (2022). Measurement of the B-s(0) -> mu(+)mu(-) decay properties and search for the B-0 -> mu(+)mu(-) and B-s(0) -> mu(+)mu(-) gamma decays. Phys. Rev. D, 105(1), 012010–34pp.
Abstract: An improved measurement of the decay B-s(0) -> mu(+)mu(-) and searches for the decays B-0 -> mu(+)mu(-) and B-s(0) -> mu(+)mu(-)gamma are performed at the LHCb experiment using data collected in proton-proton collisions at root s = 7, 8 and 13 TeV, corresponding to integrated luminosities of 1, 2 and 6 fb(-1), respectively. The B-s(0) -> mu(+)mu(-) branching fraction and effective lifetime are measured to be B(B-s(0) -> mu(+)mu(-)) = (3.09(-0.43-0.11)(+0.46+0.15)) x 10(-9) and tau(B-s(0) -> mu(+)mu(-)) = (2.07 +/- 0.29 +/- 0.03) ps, respectively, where the uncertain-ties include both statistical and systematic contributions. No significant signal for B-0 -> mu(+)mu(-) and B-s(0) -> mu(+)mu(-) gamma decays is found and the upper limits B(B-0 -> mu(+)mu(-)) < 2.6 x 10(-10) and B(B-s(0) -> mu(+)mu(-)gamma) 2.0 x 10(-9) at 95% confidence level are determined, where the latter is limited to the range m(mu mu) > 4.9 GeV/c(2). Additionally, the ratio between the B-0 -> mu(+)mu(-) and B-s(0) -> mu(+)mu(-) branching fractions is measured to be R mu+mu- < 0.095 at 95% confidence level. The results are in agreement with the Standard Model predictions.
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