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). First observation of the B+ → Ds+ Ds- K+ decay. Phys. Rev. D, 108(3), 034012–14pp.
Abstract: B+ -> D-s(+) D-s(-) K+ decay is observed for the first time using proton-proton collision data collected by the LHCb detector at center-of-mass energies of 7, 8, and 13 TeV, corresponding to an integrated luminosity of 9 fb-1. Its branching fraction relative to that of the B+ -> D-s(+) D-s(-) K+ decay is measured to be B(B+ -> D-s(+) D-s(-) K+)/(KB+ -> D-s(+) D-s(-) K+) = 0.525 +/- 0.0333 +/- 0.027 +/- 0.034; where the first uncertainty is statistical, the second s D-s Kthornthorn systematic, and the third is due to the uncertainties on the branching fractions of the D-s(+/-) -> (KK +/-)-K--/+pi(+/-) and D-+/- -> K--/+pi(+/-)pi(+/-) decays. This measurement fills an experimental gap in the knowledge of the family of Cabibbo-favored (b) over bar -> (b) over barc (c) over bar transitions and opens the path for unique studies of spectroscopy in future.
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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 KS(L)0 → μ+ μ- μ+ μ- decays at LHCb. Phys. Rev. D, 108(3), L031102–12pp.
Abstract: A search for K-S(L)(0) -> mu(+) mu(-) mu(+) mu(-) decays is performed using proton-proton collision data collected by the LHCb experiment at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5.1 fb(-1). No evidence for signal is found. The 90% confidence level upper limits are the first set for both decays and are B(K-S(0)) -> mu(+) mu(-) mu(+) mu(-)) < 5.1 x 10(-12) and B(K-L(0))-> mu(+) mu(-) mu(+) mu(-)) < 2.3 x 10(-9).
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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 the Z boson production cross-section in pp collisions at √s=5.02 TeV. J. High Energy Phys., 02(2), 070–38pp.
Abstract: The first measurement of the Z boson production cross-section at centre-of-mass energy v s = 5.02TeV in the forward region is reported, using pp collision data collected by the LHCb experiment in year 2017, corresponding to an integrated luminosity of 100 +/- 2 pb-1. The production cross-section is measured for final-state muons in the pseudorapidity range 2.0 <. < 4.5 with transverse momentum pT > 20 GeV/c. The integrated cross-section is determined to be sZ.mu+mu- = 39.6 +/- 0.7(stat) +/- 0.6(syst) +/- 0.8(lumi) pb for the di-muon invariant mass in the range 60 < M μμ< 120 GeV/c2. This result and the differential cross-section results are in good agreement with theoretical predictions at next-to-next-to-leading order in the strong coupling constant. Based on a previous LHCb measurement of the Z boson production cross-section in pPb collisions at v sNN = 5.02TeV, the nuclear modification factor RpPb is measured for the first time at this energy. The measured values are 1.2+0.5 -0.3(stat) +/- 0.1(syst) in the forward region (1.53 < y* μ< 4.03) and 3.6+1.6 -0.9(stat)+/- 0.2(syst) in the backward region (-4.97 < y* μ< -2.47), where y* μrepresents the muon rapidity in the centre-of-mass frame.
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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). A search for rare B → D μ+ μ- decays. J. High Energy Phys., 02(2), 032–23pp.
Abstract: A search for rare B. D mu+ mu- decays is performed using proton-proton collision data collected by the LHCb experiment, corresponding to an integrated luminosity of 9 fb-1. No significant signals are observed in the non-resonant mu+ mu- modes, and upper limits of B -> B0. D0 mu+ mu- < 5.1 x 10-8, B B+. D+ s mu+ mu- -> < 3.2 x 10-8, B -> B0 s. D0 mu+ mu--> < 1.6 x 10-7 and fc/fu center dot B B+ c. D+ s mu+ mu--> < 9.6 x 10-8 are set at the 95% confidence level, where fc and fu are the fragmentation fractions of a B meson with a c and u quark respectively in proton-proton collisions. Each result is either the first such measurement or an improvement by three orders of magnitude on an existing limit. Separate upper limits are calculated when the muon pair originates from a J/.. mu+ mu- decay. The branching fraction of B+ c. D+ s J/. multiplied by the fragmentation-fraction ratio is measured to be fc fu center dot B -> B+ c. D+ s J/.-> = (1.63 +/- 0.15 +/- 0.13) x 10-5, where the first uncertainty is statistical and the second systematic.
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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 the CKM angle γ in the B0 → D K*0 channel using self-conjugate D → KS0 h+ h- decays. Eur. Phys. J. C, 84(2), 206–18pp.
Abstract: A model-independent study of CP violation in B-0 -> DK (*0) decays is presented using data corresponding to an integrated luminosity of 9 fb(-1) collected by the LHCb experiment at centre-of-mass energies of v s = 7, 8 and 13TeV. The CKM angle. is determined by examining the distributions of signal decays in phase-space bins of the self-conjugate D. K(S)(0)h(+) h(-) decays, where h = p, K. Observables related to CP violation are measured and the angle. is determined to be = (49+22 -19). Measurements of the amplitude ratio and strong-phase difference between the favoured and suppressed B-0 decays are also presented.
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