Abstract: A search for the lepton-flavour violating decays B-0 -> K-*0 μe(-/+) and B-s(0)-> mu(+/-)e(-/+) is presented, using proton-proton collision data collected by the LHCb detector at the LHC, corresponding to an integrated luminosity of 9 fb(-1). No significant signals are observed and upper limits of are set at 90% (95%) confidence level. These results constitute the world's most stringent limits to date, with the limit on the decay B-s(0) -> phi mu(+/-) e(-/+) the first being set. In addition, limits are reported for scalar and left-handed lepton-flavour violating New Physics scenarios.

Abstract: A search for the lepton-flavour violating decays B-(s)(0) -> e(+/-)mu(-/+) and B-(s)(0) -> e(+/-)mu(-/+) performed based on a sample of proton-proton collision data corresponding to an integrated luminosity of 3 fb(-1), collected with the LHCb experiment at centre-of-mass energies of 7 and 8TeV. The observed yields are consistent with the background-only hypothesis. Upper limits on the branching fraction of the B-(s)(0) -> e(+/-)mu(-/+) decays are evaluated both in the hypotheses of an amplitude completely dominated by the heavy eigenstate and by the light eigenstate. The results are B(B-s(0) -> e(+/-)mu(-/+)) < 6.3 (5.4) x 10(-9) and B(B-s(0) -> e(+/-)mu(-/+)) < 7.2(6.0) x 10(-9) at 95% (90%) confidence level, respectively. The upper limit on the branching fraction of the B-0 -> e(+/-)mu(-/+) decay is also evaluated, obtaining B(B-0 -> e(+/-)mu(-/+)) < 1.3 (1.0) x 10(-9) at 95% (90%) confidence level. These are the strongest limits on these decays to date.

Abstract: A search is performed for the as yet unobserved baryonic Lambda(0)(b) -> Lambda eta' and Lambda(0)(b) -> Lambda eta decays with 3 fb(-1) of proton-proton collision data recorded by the LHCb experiment. The B-0 -> K-s(0)eta' decay is used as a normalisation channel. No significant signal is observed for the Lambda(0)(b) -> Lambda eta' decay. An upper limit is found on the branching fraction of B(Lambda(0)(b) -> Lambda eta') < 3.1 x 10(-6) at 90% confidence level. Evidence is seen for the presence of the Lambda(0)(b) -> Lambda eta 0 decay at the level of 3 sigma significance, with a branching fraction B(Lambda(0)(b) -> Lambda eta) = (9.3(-5.3)(+7.3)) x 10(-6).

Abstract: The first search for the doubly heavy Omega(0)(bc) baryon and a search for the Xi(0)(bc) baryon are performed using collision data collected via the experiment from 2016 to 2018 at a centre-of-mass energy of, corresponding to an integrated luminosity of 5.2 fb(-1). The baryons are reconstructed via their decays to Lambda(+)(-)(c)(pi) and Xi(+)(c)pi(-). No significant excess is found for invariant masses between 6700 and 7300 MeV/c(2), in a rapidity range from 2.0 to 4.5 and a transverse momentum range from 2 to 20 MeV/c. Upper limits are set on the ratio of the Omega(0)(bc) and Xi(0)(bc) production cross-section times the branching fraction to Lambda(+)(c)pi(-)(Xi(+)(c)pi(-)) relative to that of the Lambda(0)(b)(Xi(0)(b)) baryon, for different lifetime hypotheses, at 95% confidence level. The upper limits range from 0.5x10(-4) to 2.5x10(-4) for the Omega(0)(bc) -> Lambda(+)(c)pi(-) (Xi(0)(bc) -> Lambda(+)(c)pi(-)) decay, pending on the considered mass and lifetime of the Omega(0)(bc) (Xi(0)(bc)) baryon.

Abstract: A search for B-s(0) -> (D) over bar (0) f(0)(980) decays is performed using 3.0 fb(1-) of pp collision data recorded by the LHCb experiment during 2011 and 2012. The f(0)(980) meson is reconstructed through its decay to the pi(+)pi(-) final state in the mass window 900 MeV/c(2) < m (pi(+)pi(-)) < 1080 MeV/c(2). No significant signal is observed. The first upper limits on the branching fraction of B (B-s(0) -> (D) over bar (0) f(0)(980)) < 3.1 (3.4) x 10(-6) are set at 90% (95 %) confidence level.