BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2020). Measurements of the Absolute Branching Fractions of B-+/- -> K(+/-)Xc(c)over-bar. Phys. Rev. Lett., 124(15), 152001–8pp.
Abstract: A study of the two-body decays B-+/- -> Xc (c) over barK +/-, where X-c (c) over bar refers to one charmonium state, is reported by the BABAR Collaboration using a data sample of 424 fb(-1). The absolute determination of branching fractions for these decays are significantly improved compared to previous BABAR measurements. Evidence is found for the decay B-+/- -> X(3872)K+ at the 3 sigma level. The absolute branching fraction B[B+ -> X(3872)K+] = [2.1 +/- 0.6(stat) +/- 0.3(syst)] x 10(-4) is measured for the first time. It follows that B[X(3872) -> J/psi pi(+)pi(-)] = (4.1 +/- 1.3)%, supporting the hypothesis of a molecular component for this resonance.
|
BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2016). Observation of (B)over-bar -> D-(*()) pi(+)pi(-)l(-)(nu)over-bar Decays in e(+)e(-) Collisions at the Upsilon(4S) Resonance. Phys. Rev. Lett., 116(4), 041801–7pp.
Abstract: We report on measurements of the decays of (B) over bar mesons into the semileptonic final states (B) over bar -> D-(*())pi(+)pi(-)l(-)(nu) over bar, where D-(*()) represents a D or D* meson and l(-) is an electron or a muon. These measurements are based on 471 x 10(6) B (B) over bar pairs recorded with the BABAR detector at the SLAC asymmetric B factory PEP-II. We determine the branching fraction ratios R-pi+pi-(()*()) = B((B) over bar -> D-(*())pi(+)pi(-)l(-)(nu) over bar /B (B) over bar -> D-(*())l(-)(nu) over bar) using events in which the second B meson is fully reconstructed. We find R pi+pi- = 0.067 +/- 0.010 +/- 0.008 and R pi+pi-* = 0.019 +/- 0.005 +/- 0.004, where the first uncertainty is statistical and the second is systematic. Based on these results and assuming isospin invariance, we estimate that (B) over bar -> D-(*())pi pi l (nu) over bar decays, where pi denotes either a pi(+/-) and pi(0) meson, account for up to half the difference between the measured inclusive semileptonic branching fraction to charm hadrons and the corresponding sum of previously measured exclusive branching fractions.
|
BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., Oyanguren, A., & Villanueva-Perez, P. (2013). Observation of direct CP violation in the measurement of the Cabibbo-Kobayashi-Maskawa angle gamma with B-+/- -> Dd(()*()) K-(*()+/-) decays. Phys. Rev. D, 87(5), 052015–12pp.
Abstract: We report the determination of the Cabibbo-Kobayashi-Maskawa CP-violating angle gamma through the combination of various measurements involving B-+/- -> DK +/-, B-+/- -> D*K-+/-, and B-+/- -> DK*(+/-) decays performed by the BABAR experiment at the PEP-II e(+)e(-) collider at SLAC National Accelerator Laboratory. Using up to 474 million B (B) over bar pairs, we obtain gamma = (69(-16)(+17))degrees modulo 180 degrees. The total uncertainty is dominated by the statistical component, with the experimental and amplitude-model systematic uncertainties amounting to +/- 4 degrees. The corresponding two-standard-deviation region is 41 degrees < gamma < 102 degrees. This result is inconsistent with gamma = 0 with a significance of 5.9 standard deviations.
|
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).
|
BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., Oyanguren, A., & Villanueva-Perez, P. (2015). Observation of the baryonic decay (B)over-bar(0) -> Lambda(+)(c)(p)over-barK(-)K(+). Phys. Rev. D, 91(3), 031102–7pp.
Abstract: We report the observation of the baryonic decay (B) over bar (0) -> Lambda(+)(c)(p) over barK(-)K(+) using a data sample of 471 x 10(6) B (B) over bar pairs produced in e(+)e(-) annihilations at root s = 10.58 GeV. This data sample was recorded with the BABAR detector at the PEP- II storage ring at SLAC. We find B((B) over bar (0) -> Lambda(+)(c)(p) over barK(-)K(+)) = (2.5 +/- 0.4((stat)) +/- 0.2((syst)) +/- 0.6(B(Lambda c+)) ) x 10(-5) where the uncertainties are statistical, systematic, and due to the uncertainty of the Lambda(+)(c) -> (p) over barK(-)pi(+) branching fraction, respectively. The result has a significance corresponding to 5.0 standard deviations, including all uncertainties. For the resonant decay (B) over bar (0) -> Lambda(+)(c)(p) over bar phi, we determine the upper limit B((B) over bar (0) -> Lambda(+)(c)(p) over bar phi) < 1.2 x 10(-5) at 90% confidence level.
|
BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2019). Observation of the Decay D-0 -> K- pi(+) e(+) e(-). Phys. Rev. Lett., 122(8), 081802–8pp.
Abstract: We report the observation of the rare charm decay D-0 -> K-pi(+)e(+)e(-), based on 468 fb(-1) of e(+)e(-) annihilation data collected at or close to the center-of-mass energy of the (sic)(4S) resonance with the BABAR detector at the SLAC National Accelerator Laboratory. We find the branching fraction in the invariant mass range 0.675 < m(e(+)e(-)) < 0.875 GeV/c(2) of the electron-positron pair to be B(D-0 -> K-pi(+)e(+)e(-)) = (4.0 +/- 0.5 +/- 0.2 +/- 0.1) x 10(-6), where the first uncertainty is statistical, the second systematic, and the third due to the uncertainty in the branching fraction of the decay D-0 -> K-pi(+)pi(+)pi(-) used as a normalization mode. The significance of the observation corresponds to 9.7 standard deviations including systematic uncertainties. This result is consistent with the recently reported D-0 -> K-pi(+)mu(+)mu(-) branching fraction, measured in the same invariant mass range, and with the value expected in the standard model. In a set of regions of m(e(+)e(-)), where long-distance effects are potentially small, we determine a 90% confidence level upper limit on the branching fraction B(D-0 -> K-pi(+)e(+)e(-)) < 3.1 x 10(-6).
|
BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2011). Observation of the rare decay B(+) -> K(+) pi(0)pi(0) and measurement of the quasi-two-body contributions B(+) -> K* (892)(+) pi(0), B(+) -> f(0)(980)K(+), and B(+) -> chi(c0)K(+). Phys. Rev. D, 84(9), 092007–11pp.
Abstract: We report an analysis of charmless hadronic decays of charged B mesons to the final state K(+) pi(0)pi(0), using a data sample of (470.9 +/- 2.8) x 10(6) B (B) over bar events collected with the BABAR detector at the Y(4S) resonance. We observe an excess of signal events, with a significance above 10 standard deviations including systematic uncertainties, and measure the branching fraction and CP asymmetry to be B(B(+) -> K(+) pi(0)pi(0)) = (16.2 +/- 1.2 +/- 1.5) x 10(-6) and A(CP)(B(+) -> K(+) pi(0)pi(0)) = -0.06 +/- 0.06 +/- 0.04, where the uncertainties are statistical and systematic, respectively. Additionally, we study the contributions of the B(+) -> K*(892)(+) pi(0), B(+) -> f(0)(980)K(+), and B(+) -> chi(c0)K(+) quasi-two-body decays. We report the world's best measurements of the branching fraction and CP asymmetry of the B(+) -> K(+) pi(0)pi(0) and B(+) -> K(+)(892)(+) pi(0) channels.
|
BABAR Collaboration(Lees, J. P. et al), Bernabeu, J., Martinez-Vidal, F., Oyanguren, A., & Villanueva-Perez, P. (2012). Observation of Time-Reversal Violation in the B-0 Meson System. Phys. Rev. Lett., 109(21), 211801–8pp.
Abstract: Although CP violation in the B meson system has been well established by the B factories, there has been no direct observation of time-reversal violation. The decays of entangled neutral B mesons into definite flavor states (B-0 or (B) over bar (0)), and J/psi K-L(0) or c (c) over barK(S)(0) final states (referred to as B+ or B-), allow comparisons between the probabilities of four pairs of T-conjugated transitions, for example, (B) over bar (0) -> B- and B- -> (B) over bar (0), as a function of the time difference between the two B decays. Using 468 X 10(6) B (B) over bar pairs produced in Y(4S) decays collected by the BABAR detector at SLAC, we measure T-violating parameters in the time evolution of neutral B mesons, yielding Delta S-T(+) = -137 +/- 0.14(stat) +/- 0.06(syst) and Delta S-T(-) = 1.17 +/- 0.18(stat) +/- 0.11(syst). These nonzero results represent the first direct observation of T violation through the exchange of initial and final states in transitions that can only be connected by a T-symmetry transformation.
|
BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2012). Precise measurement of the e(+)e(-) -> pi(+)pi(-)(gamma) cross section with the initial-state radiation method at BABAR. Phys. Rev. D, 86(3), 032013–49pp.
Abstract: A precise measurement of the cross section of the process e(+)e(-) -> pi(+)pi(-) (gamma) from threshold to an energy of 3 GeV is obtained with the initial-state radiation (ISR) method using 232 fb(-1) of data collected with the BABAR detector at e(+)e(-) center-of-mass energies near 10.6 GeV. The ISR luminosity is determined from a study of the leptonic process e(+)e(-) -> mu(+)mu(-) (gamma)gamma(ISR), which is found to agree with the next-to-leading-order QED prediction to within 1.1%. The cross section for the process e(+)e(-) -> pi(+)pi(-) (gamma) is obtained with a systematic uncertainty of 0.5% in the dominant rho resonance region. The leading-order hadronic contribution to the muon magnetic anomaly calculated using the measured pi pi cross section from threshold to 1.8 GeV is (514.1 +/- 2.2(stat) +/- 3.1(sys)) x 10(-10).
|
BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2012). Precision Measurement of the B -> Xs gamma Photon Energy Spectrum, Branching Fraction, and Direct CP Asymmetry ACP(B -> Xs+d gamma). Phys. Rev. Lett., 109(19), 191801–8pp.
Abstract: The photon spectrum in the inclusive electromagnetic radiative decays of the B meson, B --> X-s gamma plus B --> X-d gamma, is studied using a data sample of (382.8 +/- 4.2) x 10(6)Y(4S) --> B (B) over bar decays collected by the BABAR experiment at SLAC. The spectrum is used to extract the branching fraction B(B --> X-s gamma) = (3.21 +/- 0.33) x 10(-4) for E-gamma > 1.8 GeV and the direct CP asymmetry A(CP)(B --> Xs+d gamma) = 0.057 +/- 0.063. The effects of detector resolution and Doppler smearing are unfolded to measure the photon energy spectrum in the B meson rest frame.
|
