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Search for mixing-induced CP violation using partial reconstruction of B¯0→D*+Xℓ−ν¯ℓ and kaon tagging

  • Graugés Pous, Eugeni
  • BABAR Collaboration
We describe in detail a previously published measurement of C P violation in B 0 - ¯ B 0 oscillations, based on an integrated luminosity of 425.7     fb − 1 collected by the BABAR experiment at the PEPII collider. We apply a novel technique to a sample of about 6 million ¯ B 0 → D * + ℓ − ¯ ν ℓ decays selected with partial reconstruction of the D * + meson. The charged lepton identifies the flavor of one B meson at its decay time, the flavor of the other B is determined by kaon tagging. We determine a C P violating asymmetry A C P = ( N ( B 0 B 0 ) − N ( ¯ B 0 ¯ B 0 ) ) / ( N ( B 0 B 0 ) + N ( ¯ B 0 ¯ B 0 ) ) = ( 0.06 ± 0.1 7 + 0.38 − 0.32 ) % corresponding to Δ C P = 1 − | q / p | = ( 0.29 ± 0.8 4 + 1.88 − 1.61 ) × 1 0 − 3 . This measurement is consistent and competitive with those obtained at the B factories with dilepton events.
Proyecto:


Search for Structure in the Bs0 π± Invariant Mass Spectrum

  • Badalov, Alexey
  • Camboni, Alessandro
  • Garrido Beltrán, Lluís
  • Gascón Fora, David
  • Graciani Díaz, Ricardo
  • Graugés Pous, Eugeni
  • Marin Benito, Carla
  • Picatoste Olloqui, Eduardo
  • Rives Molina, Vicente José
  • LHCb Collaboration
The B 0 s π ± invariant mass distribution is investigated in order to search for possible exotic meson states. The analysis is based on a data sample recorded with the LHCb detector corresponding to 3     fb − 1 of p p collision data at √ s = 7 and 8 TeV. No significant excess is found, and upper limits are set on the production rate of the claimed X ( 5568 ) state within the LHCb acceptance. Upper limits are also set as a function of the mass and width of a possible exotic meson decaying to the B 0 s π ± final state. The same limits also apply to a possible exotic meson decaying through the chain B * 0 s π ± , B * 0 s → B 0 s γ where the photon is excluded from the reconstructed decays.
Proyecto:


Studies of the resonance structure in D0 → KS0 K±π decays

  • Garrido Beltrán, Lluís
  • Gascón Fora, David
  • Graciani Díaz, Ricardo
  • Graugés Pous, Eugeni
  • Marin Benito, Carla
  • Picatoste Olloqui, Eduardo
  • Rives Molina, Vicente José
  • Ruiz, Hugo (Ruiz Pérez)
  • LHCb Collaboration
Amplitude models are applied to studies of resonance structure in D 0 → K 0 S K − π + and D 0 → K 0 S K + π − decays using p p collision data corresponding to an integrated luminosity of 3.0     fb − 1 collected by the LHCb experiment. Relative magnitude and phase information is determined, and coherence factors and related observables are computed for both the whole phase space and a restricted region of 100     MeV / c 2 around the K ∗ ( 892 ) ± resonance. Two formulations for the K π   S -wave are used, both of which give a good description of the data. The ratio of branching fractions B ( D 0 → K 0 S K + π − ) / B ( D 0 → K 0 S K − π + ) is measured to be 0.655 ± 0.004 ( stat ) ± 0.006 ( syst ) over the full phase space and 0.370 ± 0.003 ( stat ) ± 0.012 ( syst ) in the restricted region. A search for C P violation is performed using the amplitude models and no significant effect is found. Predictions from SU(3) flavor symmetry for K ∗ ( 892 ) K amplitudes of different charges are compared with the amplitude model results.
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Study of Bc+ decays to the K+K-π+ final state and evidence for the decay Bc+ →χc0π+

  • Coquereau, S.
  • Garrido Beltrán, Lluís
  • Gascón Fora, David
  • Graciani Díaz, Ricardo
  • Graugés Pous, Eugeni
  • Marin Benito, Carla
  • Picatoste Olloqui, Eduardo
  • Rives Molina, Vicente José
  • LHCb Collaboration
A study of B + c → K + K − π + decays is performed for the first time using data corresponding to an integrated luminosity of 3.0     fb − 1 collected by the LHCb experiment in p p collisions at center-of-mass energies of 7 and 8 TeV. Evidence for the decay B + c → χ c 0 ( → K + K − ) π + is reported with a significance of 4.0 standard deviations, giving σ ( B + c ) σ ( B + ) × B ( B + c → χ c 0 π + ) = ( 9. 8 + 3.4 − 3.0 ( stat ) ± 0.8 ( syst ) ) × 10 − 6 . Here B denotes a branching fraction while σ ( B + c ) and σ ( B + ) are the production cross sections for B + c and B + mesons. An indication of ¯ b c weak annihilation is found for the region m ( K − π + ) < 1.834     GeV / c 2 , with a significance of 2.4 standard deviations.
Proyecto:


Study of DsJ(*) + mesons decaying to D∗ +KS0 and D*0K+ final states

  • Gascón Fora, David
  • Graciani Díaz, Ricardo
  • Graugés Pous, Eugeni
  • Marin Benito, Carla
  • Picatoste Olloqui, Eduardo
  • Rives Molina, Vicente José
  • LHCb Collaboration
A search is performed for D sJ (*) + mesons in the reactions pp → D ∗ + K S 0 X and pp → D *0 K + X using data collected at centre-of-mass energies of 7 and 8 TeV with the LHCb detector. For the D ∗ + K S 0 final state, the decays D *+ → D 0 π + with D 0 → K − π + and D 0 → K − π + π + π − are used. For D *0 K +, the decay D *0 → D 0 π 0 with D 0 → K − π + is used. A prominent D s1(2536)+ signal is observed in both D ∗ + K S 0 and D *0 K + final states. The resonances D s1 * (2700)+ and D s3 * (2860)+ are also observed, yielding information on their properties, including spin-parity assignments. The decay D s2 * (2573)+ → D ∗ + K S 0 is observed for the first time, at a significance of 6.9 σ, and its branching fraction relative to the D s2 * (2573)+ → D + K S 0 decay mode is measured.
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Tests of CPT symmetry in B0- B 0 mixing and in B0 →c c K0 decays

  • Graugés Pous, Eugeni
  • BABAR Collaboration
Using the eight time dependences e − Γ t ( 1 + C i cos Δ m t + S i sin Δ m t ) for the decays Υ ( 4 S ) → B 0 ¯ B 0 → f j f k , with the decay into a flavor-specific state f j = ℓ ± X before or after the decay into a C P eigenstate f k = c ¯ c K S , L , as measured by the BABAR experiment, we determine the three C P T -sensitive parameters Re ( z ) and Im ( z ) in B 0 − ¯ B 0 mixing and | ¯ A / A | in B 0 → c ¯ c K 0 decays. We find Im ( z ) = 0.010 ± 0.030 ± 0.013 , Re ( z ) = − 0.065 ± 0.028 ± 0.014 , and | ¯ A / A | = 0.999 ± 0.023 ± 0.017 , in agreement with C P T symmetry.
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Observation of inclusive D*+- production in the decay of Upsilon (1S)

  • Graugés Pous, Eugeni
  • Garra Ticó, Jordi
  • BABAR Collaboration
Bound states of heavy quarks provide a powerful testing ground for quantum chromodynamics (QCD). Experimental studies of charmonium and bottomonium spectroscopy have helped uncover some of the key aspects of the quarkonium potential. Studies of the decays of quarkonia and of their decay products can also reveal important information on QCD processes. The hadronic decays of the narrow quarkonia, states which are below the threshold for open flavor production, are dominated by couplings to gluons and the fragmentation process into light hadrons. The decay properties of charmonia, which have a relatively low multiplicity particle content, have been extensively studied. However, little is known about the final state contents of bottomonia. In particular, scarcely any experimental information exists on the decays of bottomonium to open charm. The CLEO Collaboration has observed charm production in the decays of the b states with branching fractions of the order of 10%. The ARGUS Collaboration searched for the decay Y(1S) -- D+-X and set a limit on its branching fraction of B < 1,9% at 90% confidence level.
Proyecto:


Measurement of the gamma gamma* --> eta_c transition form factor

  • Graugés Pous, Eugeni
  • Garra Ticó, Jordi
  • BABAR Collaboration
We study the reaction e+e- --> e+e- eta_c, eta_c --> K_S K+- pi-+ and obtain eta_c mass and width values 2982.2+-0.4+-1.6 MeV/c^2 and 31.7+-1.2+-0.8 MeV, respectively. We find Gamma(eta_c --> gamma gamma)B(eta_c --> K anti-K pi)=0.374+-0.009+-0.031 keV, and measure the gamma gamma* --> eta_c transition form factor in the momentum transfer range from 2 to 50 GeV^2. The analysis is based on 469 fb-1 of integrated luminosity collected at PEP-II with the BABAR detector at e+e- center-of-mass energies near 10.6 GeV.
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A Measurement of the Semileptonic Branching Fraction of the B_s Meson

  • Graugés Pous, Eugeni
  • Garra Ticó, Jordi
  • BABAR Collaboration
We report a measurement of the inclusive semileptonic branching fraction of the B_s meson using data collected with the BaBar detector in the center-of-mass (CM) energy region above the Upsilon (4S) resonance. We use the inclusive yield of phi mesons and the phi yield in association with a high-momentum lepton to perform a simultaneous measurement of the semileptonic branching fraction and the production rate of B_s mesons relative to all B mesons as a function of CM energy. The inclusive semileptonic branching fraction of the B_s meson is determined to be B(B_s to l nu X)=9.5 (+2.5/-2.0)(stat)(+1.1/-1.9)(syst)%, where l indicates the average of e and mu.
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Search for f_J(2220) in radiative J/psi decays

  • Graugés Pous, Eugeni
  • Garra Ticó, Jordi
  • BABAR Collaboration
We present a search for fJ(2220) production in radiative J/ψ→γfJ(2220) decays using 460fb-1 of data collected with the BABAR detector at the SLAC PEP-II e+e- collider. The fJ(2220) is searched for in the decays to K+K- and KS0KS0. No evidence of this resonance is observed, and 90% confidence level upper limits on the product of the branching fractions for J/ψ→γfJ(2220) and fJ(2220)→K+K-(KS0KS0) as a function of spin and helicity are set at the level of 10-5, below the central values reported by the Mark III experiment.
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