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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). Study of the Bose-Einstein correlations of same-sign pions in proton-lead collisions. J. High Energy Phys., 09(9), 172–29pp.
Abstract: Correlations of same-sign charged pions are analysed using proton-lead collision data collected by the LHCb experiment at a nucleon-nucleon centre-of-mass energy of 5.02TeV, corresponding to an integrated luminosity of 1.06 nb(-1). Bose-Einstein correlations are observed in the form of an enhancement of pair production for same-sign charged pions with a small four-momentum difference. The dependence of the correlation radius and the intercept parameter on the reconstructed charged-particle multiplicity is investigated. The measured correlation radii scale linearly with the cube root of the reconstructed charged-particle multiplicity, being compatible with predictions of hydrodynamic models on the collision system evolution.
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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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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2011). Observation of the baryonic B decay (B)over-bar(0) -> Lambda(+)(c)(Lambda)over-barK(-). Phys. Rev. D, 84(7), 071102–7pp.
Abstract: We report the observation of the baryonic B decay (B) over bar (0) -> Lambda(+)(c)Lambda K(-) with a significance larger than 7 standard deviations based on 471 x 10(6) B (B) over bar pairs collected with the BABAR detector at the PEP-II storage ring at SLAC. We measure the branching fraction for the decay (B) over bar (0) -> Lambda(+)(c)Lambda K(-) to be (3.8 +/- 0.8(stat) +/- 0.2(sys) +/- 1.0(Lambda c)(+)) x 10(-5). The uncertainties are statistical, systematic, and due to the uncertainty in the Lambda(+)(c) branching fraction. We find that the Lambda(+)(c)K(-) invariant-mass distribution shows an enhancement above 3.5 GeV/c(2).
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BABAR Collaboration(Lees, J. P. et al), Lopez-March, N., Martinez-Vidal, F., & Oyanguren, A. (2011). Study of dipion bottomonium transitions and search for the h(b)(1P) state. Phys. Rev. D, 84(1), 011104–9pp.
Abstract: We study inclusive dipion decays using a sample of 108 x 10(6)Y(3S) events recorded with the BABAR detector. We search for the decay mode Y(3S) -> pi(+)pi(-) h(b)(1P) and find no evidence for the bottomonium spin-singlet state h(b)(1P) in the invariant mass distribution recoiling against the pi(+)pi(-) system. Assuming the h(b)(1P) mass to be 9.900 GeV/c(2), we measure the upper limit on the branching fraction B[Y(3S) -> pi(+)pi(-) h(b)(1P)] < 1.2 x 10(-4), at 90% confidence level. We also investigate the chi(bJ)(2P) -> pi(+)pi(-) chi(bJ)(1P), Y(3S) -> pi(+)pi(-) Y(2S), and Y(2S) -> pi(+)pi(-) Y(1) dipion transitions and present an improved measurement of the branching fraction of the Y(3S) -> pi(+)pi(-) Y(2S) decay and of the Y(3S) – Y(2S) mass difference.
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2011). Search for CP violation using T-odd correlations in D(+) -> K(+)K(S)(0) pi(+)pi(-) and D(s)(+) -> K(+)K(S)(0) pi(+)pi(-) decays. Phys. Rev. D, 84(3), 031103–9pp.
Abstract: We search for CP violation in a sample of 20 000 Cabibbo-suppressed decays, D(+) -> K(+)K(S)(0)pi(+)pi(-), and 30 000 Cabibbo-favored decays, D(+) -> K(+)K(S)(0)pi(+)pi(-). We use 520 fb(-1) of data recorded by the BABAR detector at the PEP-II asymmetric-energy e(+)e(-) collider operating at center of mass energies near 10.6 GeV. We search for CP violation in the difference between the T-odd asymmetries obtained using triple product correlations of the D(+)(D(s)(+)) and D(-)(D(s)(-)) decays, respectively. The T violation parameter values obtained are A(T)(D(+)) = (-12.0 +/- 10.0(stat) +/- 4.6(syst)) x 10(-3) and A(T)(D(s)(+)) = (-13.6 +/- 7.7(stat) +/- 3.4(syst)) x 10(-3), which are consistent with the standard model expectations.
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2011). Study of Y(3S, 2S) -> eta Y(1S) and Y(3S, 2S) -> pi(+) pi(-) Y(1S) hadronic transitions. Phys. Rev. D, 84(9), 092003–8pp.
Abstract: We study the Y(3S, 2S) -> eta Y(1S) and Y (3S,2S) -> pi(+)pi(-) transitions with 122 x 10(6) x Y(3S) and 100 x 10(6) Y (2S) mesons collected by the BABAR detector at the PEP-II asymmetric-energy e(+)e(-) collider. We measure B[Y(2S) -> eta Y(1S)] = (2.39 +/- 0.31 (stat) +/- 0.14(syst)) x 10(-4) and Gamma[Y(2S) -> eta Y(1S)]/Gamma[Y(2S) ->pi(+)pi(-)(1S)] – (2.39 +/- 0.31(stat) +/- 0.14(syst)) x 10(-3). We find no evidence for Y(3S) -> eta Y (1S) and obtain B[Y(3S) -> eta Y(1S)] < 1.0 x 10(-4) and Gamma[Y (3S) -> eta Y(1S)/Gamma[Y(3S) -> pi(+)pi(-) Y(1S)] < 2.3 x 10(-3) as upper limits at the 90% confidence level. We also provide improved measurements of the Y(S) – Y(1S) and Y(3S) – Y (1S) mass differences, 562.170 +/- 0.007(stat) +/- 0.088(syst). MeV/c(2) and 893.813 +/- 0: 015(stat) +/- 0.107(syst.) MeV/c(2), respectively.
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BABAR Collaboration(Lees, J. P. et al), Lopez-March, N., Martinez-Vidal, F., & Oyanguren, A. (2011). Search for b -> u transitions in B(+/-) -> [K(-/+)pi(+/-)pi(0)](D)K(+/-) decays. Phys. Rev. D, 84(1), 012002–10pp.
Abstract: We present a study of the decays B(+) -> DK(+) with D mesons reconstructed in the K(+)pi(-)pi(0) or K(-)pi(+)pi(0) final states, where D indicates a D(0) or a (D) over bar (0) meson. Using a sample of 474 x 10(6) B (B) over bar pairs collected with the BABAR detector at the PEP- II asymmetric- energy e(+)e(-) collider at SLAC, we measure the ratios R +/- equivalent to Gamma(B(+)->[K(-/+)pi(+)pi(0)](D)K(+))/Gamma(B(+)->[K(+)pi(-/+)pi(0)](D) K(+)). We obtain R+ = (5(-10)(+12)(stat)(4)(2)(syst)) X 10(-3) and R(-) = (12(-10)(+12)(stat)(-5)(+3)(syst)) X 10(-3), from which we extract the upper limits at 90% probability: R(+) < 23 X 10(-3) and R- < 29 X 10(-3). Using these measurements, we obtain an upper limit for the ratio r(B) of the magnitudes of the b -> u and b -> c amplitudes r(B) < 0.13 at 90% probability.
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BABAR Collaboration(Lees, J. P. et al), Lopez-March, N., Martinez-Vidal, F., & Oyanguren, A. (2011). Searches for rare or forbidden semileptonic charm decays. Phys. Rev. D, 84(7), 072006–13pp.
Abstract: We present searches for rare or forbidden charm decays of the form X(c)(+) -> h(+/-)l(+/-)l((l)+), where X(c)(+) is a charm hadron (D(+), D(s)(+), or A(c)(+)), h +/- is a pion, kaon, or proton, and l((l)+/-) is an electron or muon. The analysis is based on 384 fb(-1) of e(+)e(-) annihilation data collected at or close to the gamma(4S) resonance with the BABAR detector at the SLAC National Accelerator Laboratory. No significant signal is observed for any of the 35 decay modes that are investigated. We establish 90% confidence-level upper limits on the branching fractions between 1 x 10(-6) and 44 x 10(-6) depending on the channel. In most cases, these results represent either the first limits or significant improvements on existing limits for the decay modes studied.
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BABAR Collaboration(Lees, J. P. et al), Lopez-March, N., Martinez-Vidal, F., & Oyanguren, A. (2011). Measurements of branching fractions and CP asymmetries and studies of angular distributions for B -> phi phi K decays. Phys. Rev. D, 84(1), 012001–13pp.
Abstract: We present branching fraction and CP asymmetry measurements as well as angular studies of B -> phi phi K decays using 464 x 10(6) B (B) over bar events collected by the BABAR experiment. The branching fractions are measured in the phi phi invariant mass range below the eta(c) resonance (m(phi phi) < 2.85 GeV). We find B(B(+) -> phi phi K(+)) = (5.6 +/- 0.5 +/- 0.3) x 10(-6) and B(B(0) -> phi phi K(0)) = (4.5 +/- 0.8 +/- 0.3) x 10(-6), where the first uncertainty is statistical and the second systematic. The measured direct CP asymmetries for the B(+/-) decays are A(CP) = -0.10 +/- 0.08 +/- 0: 02 below the eta(c) threshold (m(phi phi) < 2.85 GeV) and A(CP) = 0.09 +/- 0.10 +/- 0.02 in the eta(c) resonance region (m(phi phi) in [2.94, 3.02] GeV). Angular distributions are consistent with J(P) = 0(-) in the eta(c) resonance region and favor J(P) = 0(+) below the eta(c) resonance.
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BABAR Collaboration(Lees, J. P. et al), Lopez-March, N., Martinez-Vidal, F., & Oyanguren, A. (2011). Study of radiative bottomonium transitions using converted photons. Phys. Rev. D, 84(7), 072002–17pp.
Abstract: We use (111 +/- 1) million Gamma(3S) and (89 +/- 1) million Gamma(2S) events recorded by the BABAR detector at the PEP-II B-factory at SLAC to perform a study of radiative transitions between bottomonium states using photons that have been converted to e(+)e(-) pairs by the detector material. We observe Gamma(3S) -> gamma chi b(0,2)(1P) decay, make precise measurements of the branching fractions for chi b(1,2)(1P, 2P) -> gamma Gamma(1S) and chi b(1,2)(2P) -> gamma Gamma(2S) decays, and search for radiative decay to the eta(b)(1S) and eta(b)(2S) states.
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