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), Henry, L., Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., et al. (2022). Precise determination of the B-s(0)-B-s(-0) oscillation frequency. Nat. Phys., 18, 54–58.
Abstract: Mesons comprising a beauty quark and strange quark can oscillate between particle (B-s(0)) and antiparticle (B-s(-0)) flavour eigenstates, with a frequency given by the mass difference between heavy and light mass eigenstates, Delta m(s). Here we present a measurement of Delta m(s) using B-s(0) -> D-s(-)pi(+) decays produced in proton-proton collisions collected with the LHCb detector at the Large Hadron Collider. The oscillation frequency is found to be Delta m(s) = 17.7683 +/- 0.0051 +/- 0.0032 ps(-1), where the first uncertainty is statistical and the second is systematic. This measurement improves on the current Delta m(s) precision by a factor of two. We combine this result with previous LHCb measurements to determine Delta m(s) = 17.7656 +/- 0.0057 ps(-1), which is the legacy measurement of the original LHCb detector.
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LHCb Collaboration(Aaij, R. et al), Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., & Ruiz Vidal, J. (2022). Measurement of the W boson mass. J. High Energy Phys., 01(1), 036–38pp.
Abstract: The W boson mass is measured using proton-proton collision data at root s = 13 TeV corresponding to an integrated luminosity of 1.7fb(-1) recorded during 2016 by the LHCb experiment. With a simultaneous fit of the muon q/p(T) distribution of a sample of W ->mu y decays and the phi* distribution of a sample of Z -> μμdecays the W boson mass is determined to be m(W )= 80354 +/- 23(stat )+/- 10(exp) +/- 17(theory) +/- 9(PDF) MeV, where uncertainties correspond to contributions from statistical, experimental systematic, theoretical and parton distribution function sources. This is an average of results based on three recent global parton distribution function sets. The measurement agrees well with the prediction of the global electroweak fit and with previous measurements.
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LHCb Collaboration(Aaij, R. et al), Jashal, B. K., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., & Ruiz Vidal, J. (2022). Study of B-c(+) decays to charmonia and three light hadrons. J. High Energy Phys., 01(1), 065–28pp.
Abstract: Using proton-proton collision data, corresponding to an integrated luminosity of 9 fb(-1) collected with the LHCb detector, seven decay modes of the B-C(+) meson into a J/psi or psi(2S) meson and three charged hadrons, kaons or pions, are studied. The decays B-C (+)-> (psi(2S) -> J/psi pi(+)pi(-))pi(+), B+C -> (psi(2S)pi(+)pi(-)pi(+), B+C -> J/psi K+pi(-)pi(+) and B+C -> J/K+K-K+ are observed for the first time, and evidence for the B-C (+)-> (psi(2S)K+K-pi(+), decay is found, where J/psi and psi(2S) mesons are reconstructed in their dimuon decay modes. The ratios of branching fractions between the different B-C(+) decays are reported as well as the fractions of the decays proceeding via intermediate resonances. The results largely support the factorisation approach used for a theoretical description of the studied decays.
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2022). Search for Darkonium in e(+) e(-) Collisions. Phys. Rev. Lett., 128(2), 021802–7pp.
Abstract: Collider searches for dark sectors, new particles interacting only feebly with ordinary matter, have largely focused on identifying signatures of new mediators, leaving much of dark sector structures unexplored. In particular, the existence of dark matter bound states (darkonia) remains to be investigated. This possibility could arise in a simple model in which a dark photon (A') is light enough to generate an attractive force between dark fermions. We report herein a search for a J(PC) = 1(--) darkonium state, the Upsilon(D), produced in the reaction e(+) e(-) -> gamma Upsilon(D), Upsilon(D) -> A'A'A', where the dark photons subsequently decay into pairs of leptons or pions, using 514 fb(-1) of data collected with the BABAR detector. No significant signal is observed, and we set bounds on the gamma – A' kinetic mixing as a function of the dark sector coupling constant for 0.001 < m(A)' < 3.16 GeV and 0.05 < m(Upsilon D) < 9.5 GeV.
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