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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). 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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Nieves, J., Pich, A., & Ruiz Arriola, E. (2011). Large-N(C) properties of the rho and f(0)(600) mesons from unitary resonance chiral dynamics. Phys. Rev. D, 84(9), 096002–20pp.
Abstract: We construct pi pi amplitudes that fulfill exact elastic unitarity, account for one-loop chiral perturbation theory contributions and include all 1/N(C) leading terms, with the only limitation of considering just the lowest-lying nonet of exchanged resonances. Within such a scheme, the N(C) dependence of sigma and rho masses and widths is discussed. Robust conclusions are drawn in the case of the rho resonance, confirming that it is a stable meson in the limit of a large number of QCD colors, N(C). Less definitive conclusions are reached in the scalar-isoscalar sector. With the present quality of data, we cannot firmly conclude whether or not the N(C) = 3 f(0)(600) resonance completely disappears at large N(C) or if it has a subdominant component in its structure, which would become dominant for a number of quark colors sufficiently large.
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Rodejohann, W., & Valle, J. W. F. (2011). Symmetrical parametrizations of the lepton mixing matrix. Phys. Rev. D, 84(7), 073011–6pp.
Abstract: Advantages of the original symmetrical form of the parametrization of the lepton mixing matrix are discussed. It provides a conceptually more transparent description of neutrino oscillations and lepton number violating processes like neutrinoless double beta decay, clarifying the significance of Dirac and Majorana phases. It is also ideal for parametrizing scenarios with light sterile neutrinos.
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Agullo, I., Navarro-Salas, J., Olmo, G. J., & Parker, L. (2011). Remarks on the renormalization of primordial cosmological perturbations. Phys. Rev. D, 84(10), 107304–5pp.
Abstract: We briefly review the need to perform renormalization of inflationary perturbations to properly work out the physical power spectra. We also summarize the basis of (momentum-space) renormalization in curved spacetime and address several misconceptions found in recent literature on this subject.
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Achilli, A., Srivastava, Y., Godbole, R., Grau, A., Pancheri, G., & Shekhovtsova, O. (2011). Total and inelastic cross sections at LHC at root s=7 TeV and beyond. Phys. Rev. D, 84(9), 094009–14pp.
Abstract: We discuss expectations for the total and inelastic cross sections at LHC CM energies root s = 7 TeV and 14 TeV obtained in an eikonal minijet model augmented by soft gluon k(t)-resummation, which we describe in some detail. We present a band of predictions which encompass recent LHC data and suggest that the inelastic cross section described by two-channel eikonal models include only uncorrelated processes. We show that this interpretation of the model is supported by the LHC data.
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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). Evidence for the h(b)(1P) meson in the decay Y(3S) -> pi(0)h(b)(1P). Phys. Rev. D, 84(9), 091101–8pp.
Abstract: Using a sample of 122 x 10(6) Y(3S) events recorded with the BABAR detector at the PEP-II asymmetric-energy e(+)e(-) collider at SLAC, we search for the h(b)(1P) spin-singlet partner of the P-wave X(bJ)(1P) states in the sequential decay Y(3S) -> pi(0)h(b) (1P), hb(1P) -> gamma eta(b)(1S). We observe an excess of events above background in the distribution of the recoil mass against the pi(0) at mass 9902 +/- 4(stat) +/- 2(syst) MeV/c(2). The width of the observed signal is consistent with experimental resolution, and its significance is 3.1 sigma, including systematic uncertainties. We obtain the value (4.3 +/- 1.1(stat) +/- 0.9(syst) x 10(-4) for the product branching fraction B(Y(3S) -> pi(0)h(b)) XB (h(b) -> gamma eta(b))
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Gonzalez, P., Mathieu, V., & Vento, V. (2011). Heavy meson interquark potential. Phys. Rev. D, 84(11), 114008–7pp.
Abstract: The resolution of Dyson-Schwinger equations leads to the freezing of the QCD running coupling (effective charge) in the infrared, which is best understood as a dynamical generation of a gluon mass function, giving rise to a momentum dependence which is free from infrared divergences. We calculate the interquark static potential for heavy mesons by assuming that it is given by a massive One Gluon Exchange interaction and compare with phenomenologyical fits inspired by lattice QCD. We apply these potential forms to the description of quarkonia and conclude that, even though some aspects of the confinement mechanism are absent in the Dyson-Schwinger formalism, the spectrum can be reasonably reproduced. We discuss possible explanations for this outcome.
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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.
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