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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. (2024). Measurement of prompt D+ and Ds+ production in pPb collisions at √s_NN=5.02 TeV. J. High Energy Phys., 01(1), 070–43pp.
Abstract: The production of prompt D+ and D-s(+) mesons is studied in proton-lead collisions at a centre-of-mass energy of root s(NN) = 5.02TeV. The data sample corresponding to an integrated luminosity of (1.58 +/- 0.02)nb(-1) is collected by the LHCb experiment at the LHC. The differential production cross-sections are measured using D+ and D-s(+) candidates with transverse momentum in the range of 0 < p(T) < 14 GeV/c and rapidities in the ranges of 1.5 < y* < 4.0 and -5.0 < y* < -2.5 in the nucleon-nucleon centre-of-mass system. For both particles, the nuclear modification factor and the forward-backward production ratio are determined. These results are compared with theoretical models that include initial-state nuclear effects. In addition, measurements of the cross-section ratios between D+, D-s(+) and D-0 mesons are presented, providing a baseline for studying the charm hadronization in lead-lead collisions at LHC energies.
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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), Jaimes Elles, S. J., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Rebollo De Miguel, M., et al. (2023). Measurement of the Prompt D0 Nuclear Modification Factor in p-Pb Collisions at √SNN=8.16 TeV. Phys. Rev. Lett., 131(10), 102301–12pp.
Abstract: The production of prompt D0 mesons in proton-lead collisions in both the forward and backward rapidity regions at a center-of-mass energy per nucleon pair of √SNN= = 8.16 TeV is measured by the sNN LHCb experiment. The nuclear modification factor of prompt D0 mesons is determined as a function of the transverse momentum pT, and the rapidity in the nucleon-nucleon center-of-mass frame y*. In the forward rapidity region, significantly suppressed production with respect to pp collisions is measured, which provides significant constraints on models of nuclear parton distributions and hadron production down to the very low Bjorken-x region of similar to 10-5. In the backward rapidity region, a suppression with a significance of 2.0-3.8 standard deviations compared to parton distribution functions in a nuclear environment expectations is found in the kinematic region of pT 6 GeV/c and -3.25 < y* < -2.5, corresponding to x similar to 0.01.
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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). Evidence for the decays B0 → (D)over-bar(*)0 φ and updated measurements of the branching fractions of the Bs0 → (D)over-bar(*)0 φ decays. J. High Energy Phys., 10(10), 123–26pp.
Abstract: Evidence for the decays B-0 -> (D) over bar (0)phi and B-0 -> (D) over bar (*0) phi is reported with a significance of 3.6 sigma and 4.3 sigma, respectively. The analysis employs pp collision data at centre-of-mass energies root s = 7, 8 and 13TeV collected by the LHCb detector and corresponding to an integrated luminosity of 9 fb(-1). The branching fractions are measured to be B(B-0 -> (D) over bar (0)phi) = (7.7 +/- 2.1 +/- 0.7 +/- 0.7) x 10(-7), B(B-0 -> (D) over bar (*0)phi) = (2.2 +/- 05 +/- 0.2 +/- 0.2) x 10(-6). In these results, the first uncertainty is statistical, the second systematic, and the third is related to the branching fraction of the B-0 -> (D) over bar K-0(+) K- decay, used for normalisation. By combining the branching fractions of the decays B-0 -> (D) over bar ((*)0)phi and B-0 -> (D) over bar ((*)0)omega, the omega-phi mixing angle delta is constrained to be tan(2)delta = (3.6 +/- 0.7 +/- 0.4) x 10(-3), where the first uncertainty is statistical and the second systematic. An updated measurement of the branching fractions of the B-s(0) -> (D) over bar ((*)0).phi decays, which can be used to determine the CKM angle gamma, leads to B(B-s(0) -> (D) over bar (0)phi) = (2.30 +/- 0.10 +/- 0.11 +/- 0.20) x 10(-5), B(B-s(0) -> (D) over bar (*0)phi) = (3.17 +/- 0.16 +/- 0.17 +/- 0.27) x 10(-5).
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