Abstract: The ratio of prompt production cross-sections of psi(2S) and J/psi mesons in their dimuon final state is measured as a function of centrality, using data collected by the LHCb detector in PbPb collisions at root s(NN) = 5.02 TeV, for the first time in the forward rapidity region. The measured ratio shows no dependence on the collision centrality, and is compared to the latest theory predictions and to the recent measurements in literature.

Abstract: The Standard Model of particle physics-the theory of particles and interactions at the smallest scale-predicts that matter and antimatter interact differently due to violation of the combined symmetry of charge conjugation (C) and parity (P). Charge conjugation transforms particles into their antimatter particles, whereas the parity transformation inverts spatial coordinates. This prediction applies to both mesons, which consist of a quark and an antiquark, and baryons, which are composed of three quarks. However, despite having been discovered in various meson decays, CP violation has yet to be observed in baryons, the type of matter that makes up the observable Universe. Here we report a study of the decay of the beauty baryon Lambda(b)(0) to the pK(-)pi(+)pi(-) final state, which proceeds through b -> u or b -> s quark-level transitions, and its CP-conjugated process, using data collected by the Large Hadron Collider beauty experiment(1) at the European Organization for Nuclear Research (CERN). The results reveal significant asymmetries between the decay rates of the Lambda(b)(0) baryon and its CP-conjugated antibaryon, providing, to our knowledge, the first observation of CP violation in baryon decays and demonstrating the different behaviours of baryons and antibaryons. In the Standard Model, CP violation arises from the Cabibbo-Kobayashi-Maskawa mechanism(2), and new forces or particles beyond the Standard Model could provide further contributions. This discovery opens a new path in the search for physics beyond the Standard Model.

Abstract: A study is presented of B+ -> (KSK-)-K-0 pi K-+(+) and B+ -> (KSK+)-K-0 pi K--(+) decays based on the analysis of proton-proton collision data collected with the LHCb detector at center-of- mass energies of 7, 8 and 13 TeV, corresponding to an integrated luminosity of 9 fb(-1). The (KSK)-K-0 pi invariant-mass distributions of both Bthorn decay modes show, in the m((KSK)-K-0 pi) < 1.85 GeV mass region, large activity which is resolved using an amplitude analysis. A simple model, where J(PC) amplitudes are described by multiple Breit-Wigner functions with appropriate angular distributions, provides a good description of the experimental data. In this approach a complex mixture of J(PC) = 0(-+), 1(++) and 1(-+) amplitudes is observed that is dominated by eta(1405), eta(1470), eta(1760), f 1o1285THORN, f(1)(1420) and h(1)(1405) resonances. The (KSK)-K-0 pi Dalitz plots are dominated by asymmetric crossing K*(K) over bar bands which are different for the two Bthorn decay modes. This is due to a different interference pattern between the 1(++) and 1(+-) amplitudes in the two channels. Branching fractions are measured for each resonant contribution.

Abstract: The branching fraction of the decay B+ ->psi(2S)phi(1020)K+, relative to the topologically similar decay B+ -> J psi phi(1020)K+, is measured using proton-proton collision data collected by the LHCb experiment at center-of-mass energies of 7, 8, and 13 TeV, corresponding to an integrated luminosity of 9 fb(-1). The ratio is found to be 0.061 +/- 0.004 +/- 0.009, where the first uncertainty is statistical and the second systematic. Using the world-average branching fraction for B+ -> J psi phi(1020)K+, the branching fraction for the decay B+ ->psi(2S)phi(1020)K+ is found to be (3.0 +/- 0.2 +/- 0.5 +/- 0.2) x 10(-6), where the first uncertainty is statistical, the second systematic, and the third is due to the branching fraction of the normalization channel.

Abstract: An amplitude analysis of B- -> D- (DKS0)-K-0 decays is performed using proton-proton collision data, corresponding to an integrated luminosity of 9 fb(-1), collected with the LHCb detector at center-of-mass energies of 7, 8, and 13 TeV. A resonant structure of spin-parity 0(+) is observed in the (DKS0)-K-0 invariant-mass spectrum with a significance of 5.3s. The mass and width of the state, modeled with a Breit-Wigner line shape, are determined to be 2883 +/- 11 +/- 8 MeV/c(2) and 87(-47)(+22) +/- 17 MeV, respectively, where the first uncertainties are statistical and the second systematic. These properties and the quark content are consistent with those of the open-charm tetraquark candidate T-cs0(*)(2870)(0) observed previously in the D+K- final state of the B- -> D-D+K- decay. This result confirms the existence of the T-cs0(*)(2870)(0) state in a new decay mode. The T-c10(*) (2900)(0) state, reported in the B- -> D-D+K- decay, is also searched for in the (DKS0)-K-0 invariant-mass spectrum of the B- -> D- (DKS0)-K-0 decay, without finding evidence for it.