415 research outputs found

    Study of the Reactions BDππB \to D^* \pi \pi and BDρπB \to D^* \rho \pi

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    We evaluate the non leptonic decays BDππB \to D^* \pi \pi and BDρπB \to D^* \rho \pi in the limit of infinitely heavy quarks, assuming the dominance of intermediate positive parity charmed resonances. We find that the branching ratios are of the order 10(3)10^(-3).Comment: 9 pages, LaTex, BARI-TH/92-13

    Quantum non-demolition measurement enables macroscopic Leggett-Garg tests

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    We show how a test of macroscopic realism based on Leggett-Garg inequalities (LGIs) can be performed in a macroscopic system. Using a continuous-variable approach, we consider quantum non-demolition (QND) measurements applied to atomic ensembles undergoing magnetically-driven coherent oscillation. We identify measurement schemes requiring only Gaussian states as inputs and giving a significant LGI violation with realistic experimental parameters and imperfections. The predicted violation is shown to be due to true quantum effects rather than to a classical invasivity of the measurement. Using QND measurements to tighten the "clumsiness loophole" forces the stubborn macrorealist to re-create quantum back action in his or her account of measurement

    Probing Universal Extra Dimensions through rare decays induced by bsb \to s transition

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    A few Bd,sB_{d,s} and Λb\Lambda_b decays induced by bsb \to s transition are studied in the Standard Model and in the framework of the Appelquist, Cheng and Dobrescu (ACD) model, which is a New Physics scenario where a single universal extra dimension is considered. In particular, we investigate the sensitivity of the observables to the radius RR of the compactified extra dimension.Comment: LaTex, 7 pages, 4 eps figures. Contribution to the International Workshop QCD@Work 2007, June 16-20, Martina Franca - Ital

    Evading 1/m_b-suppressed IR divergencies in QCDF: Bs-->KK Decays and B_{d,s} mixing

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    We analyze the deviations of the mixing induced CP asymmetry in B-->phi Ks from sin(2beta), as well as the deviations of the asymmetries in Bs-->K*K*, Bs-->phi K* and Bs-->phi phi from sin(2beta_s), that arise in SM due to penguin pollution. We use a theoretical input which is short-distance dominated in QCD-factorization and thus free of IR-divergencies. We also provide alternative ways to extract angles of the unitarity triangle from penguin-mediated decays, and give predictions for Bs-->K*K* observables.Comment: 5 pages. Talk given at the International Workshop on Quantum Chromodynamics: QCD@Work 2007, Martina Franca, Italy, June 200

    Instabilities in two flavor quark matter

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    I discuss briefly the instabilities of two flavor quark matter, paying attention to the gradient instability which develops in the g2SC phase in the Goldstone U(1)AU(1)_A sector.Comment: 6 pages. Talk given at QCD@Work07, Martina Franca (Italy). Some typos corrected, one reference adde

    Instabilities in two flavor quark matter

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    I discuss briefly the instabilities of two flavor quark matter, paying attention to the gradient instability which develops in the g2SC phase in the Goldstone U(1)AU(1)_A sector.Comment: 6 pages. Talk given at QCD@Work07, Martina Franca (Italy). Some typos corrected, one reference adde

    Possible crossover from BCS superconductivity to Bose-Einstein condensate in quark matter

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    The possibility of the crossover from the BCS pairing to the Bose-Einstein condensate (BEC) of diquarks with going down in density is discussed in the framework of in the Nambu Jona-Lasinio (NJL) model. We find that the quark matter at moderate density may be close to the intermediate of the crossover, the precursory regime to the BEC phase.Comment: 6 pages, 4 figures, Contributed to International Workshop on Quantum Chromodynamics: QCD@Work 2007, Martina Franca, Valle d'Itria, Italy, 16-20 Jun 200

    Chiral Lagrangians with tensor sources

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    The implementation of tensor sources in Chiral Lagrangians allows the computation of Green functions and form factors involving tensor currents, that is, quark bilinears of the form \bar{q}_i\sigma^{\mu\nu}q_j. Whereas only four new terms show up at O(p^4), we find around a hundred of them at O(p^6). So it becomes essential to ensure that this set o operators is indeed minimal and non-redundant (i.e., it is a basis). We discuss two phenomenological applications in the context of vector meson resonances and the radiative pion decay.Comment: Talk given at the 4th International Worshop on Quantum ChromoDynamics, Theory and experiment, June 16-20, 2007. Martina Franca - Valle d'Itria - Ital
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