LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Henry, L., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., et al. (2020). (U)pdated measurement of decay-time-dependent CP asymmetries in D-0 -> K+ K- and D-0 -> pi(+)pi(-) decays. Phys. Rev. D, 101(1), 012005–12pp.
Abstract: A search for decay-time-dependent charge-parity (CP) asymmetry in D-0 -> K+ K- and D-0 -> pi(+)pi(-) eff decays is performed at the LHCb experiment using proton-proton collision data recorded at a center-of-mass energy of 13 TeV, and corresponding to an integrated luminosity of 5.4 fb(-1). The D-0 mesons are required to originate from semileptonic decays of b hadrons, such that the charge of the muon identifies the flavor of the neutral D meson at production. The asymmetries in the effective decay widths of D-0 and (D) over bar (0) mesons are determined to be A(Gamma)(K+ K-) = (-4.3 +/- 3.6 +/- 0.5) x 10(-4) and A(Gamma) (K+ K- ) = (2.2 +/- 7.0 +/- 0.8) x 10(-4), where the uncertainties are statistical and systematic, respectively. The results are consistent with CP symmetry and, when combined with previous LHCb results, yield A(Gamma) (K+ K-) = (-4.4 +/- 2.3 +/- 0.6) x 10(-4) and A(Gamma) (pi(+)pi(-))= (2.5 +/- 4.3 +/- 0.7) x 10(-4).
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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). Observation of Several Sources of CP Violation in B+ -> pi(+)pi(+)pi(-) Decays. Phys. Rev. Lett., 124(3), 031801–11pp.
Abstract: Observations are reported of different sources of CP violation from an amplitude analysis of B+ -> pi(+)pi(+)pi(-) decays, based on a data sample corresponding to an integrated luminosity of 3 fb(-1) of pp collisions recorded with the LHCb detector. A large CP asymmetry is observed in the decay amplitude involving the tensor f(2)(1270) resonance, and in addition significant CP violation is found in the pi(+)pi S- wave at low invariant mass. The presence of CP violation related to interference between the pi(+)pi S- wave and the P wave B+ -> rho(770)(0)pi(+) amplitude is also established; this causes large local asymmetries but cancels when integrated over the phase space of the decay. The results provide both qualitative and quantitative new insights into CP -violation effects in hadronic B decays.
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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). Amplitude analysis of the B+ -> pi(+)pi(+)pi(-) decay. Phys. Rev. D, 101(1), 012006–46pp.
Abstract: The results of an amplitude analysis of the charmless three-body decay B+ -> pi(+)pi(+)pi(-) , in which CP-violation effects are taken into account, are reported. The analysis is based on a data sample corresponding to an integrated luminosity of 3 fb(-1) of pp collisions recorded with the LHCb detector. The most challenging aspect of the analysis is the description of the behavior of the pi(+)pi(-) S-wave contribution, which is achieved by using three complementary approaches based on the isobar model, the K-matrix formalism, and a quasi-model-independent procedure. Additional resonant contributions for all three methods are described using a common isobar model, and include the rho(770)(0), omega(782)(0) and rho(1450)(0) resonances in the pi(+)pi(-) P-wave, the f(2) (1270) resonance in the pi(+)pi D- -wave, and the rho(3) (1690)(0) resonance in the pi(+)pi(-) F-wave. Significant CP-violation effects are observed in both S- and D-waves, as well as in the interference between the S- and P-waves. The results from all three approaches agree and provide new insight into the dynamics and the origin of CP-violation effects in B+ -> pi(+)pi(+)pi(-) decays.
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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), Garcia Martin, L. M., Henry, L., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., et al. (2019). A search for Xi(++)(cc) -> D(+)pK(-)pi(+) decays. J. High Energy Phys., 10(10), 124–21pp.
Abstract: A search for the Xi(++)(cc) baryon through the Xi(++)(cc) -> D(+)pK(-)pi(+) decay is performed with a data sample corresponding to an integrated luminosity of 1.7 fb(-1) recorded by the LHCb experiment in pp collisions at a centre-of-mass energy of 13 TeV. No significant signal is observed in the mass range from the kinematic threshold of the decay to 3800 MeV/c(2). An upper limit is set on the ratio of branching fractions R = B(Xi(++)(cc) -> D(+)pK(-)pi(+))/B(Xi(++)(cc) -> A(c)(+) K- pi(+)pi(+)) with R < 1.7 (2.1) x 10(-2) at the 90% (95%) confidence level at the known mass of the Xi(++)(cc) state.
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