595 research outputs found

    Radiative corrections to hard spectator scattering in BππB\to \pi\pi decays

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    We present the calculation of the next-to-leading corrections to the tree amplitudes which appear in the description of non-leptonic B-decays in the factorization approach. These corrections, together with radiative corrections to the jet functions, represent the full next-to-leading contributions to the dominant hard spectator scattering term generated by operators O1,2O_{1,2} in the decay amplitudes. Using obtained analytical results we estimate BππB\to\pi\pi branchings fractions in the physical (or BBNS) factorization scheme. We have also found that the imaginary part generated in the hard spectator scattering term is rather large compared to the imaginary part of the vertex contribution.Comment: text is improved and typos are corrected, accepted for publication in JHE

    Constraining the Unitarity Triangle with B -> V gamma

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    We discuss the exclusive radiative decays BKγB\to K^{*}\gamma, BργB \to\rho\gamma, and BωγB\to\omega\gamma in QCD factorization within the Standard Model. The analysis is based on the heavy-quark limit of QCD. Our results for these decays are complete to next-to-leading order in QCD and to leading order in the heavy-quark limit. Special emphasis is placed on constraining the CKM-unitarity triangle from these observables. We propose a theoretically clean method to determine CKM parameters from the ratio of the BρlνB\to\rho l\nu decay spectrum to the branching fraction of BργB\to\rho\gamma. The method is based on the cancellation of soft hadronic form factors in the large energy limit, which occurs in a suitable region of phase space. The ratio of the BργB\to\rho\gamma and BKγB\to K^{*}\gamma branching fractions determines the side RtR_{t} of the standard unitarity triangle with reduced hadronic uncertainties. The recent Babar bound on B(B0ρ0γ)B(B^0\to\rho^0\gamma) implies Rt<0.81(ξ/1.3)R_t < 0.81 (\xi/1.3), with the limiting uncertainty coming only from the SU(3) breaking form factor ratio ξ\xi. This constraint is already getting competitive with the constraint from BsB_{s}-Bˉs\bar B_{s} mixing. Phenomenological implications from isospin-breaking effects are briefly discussed.Comment: 23 pages, 8 figure

    A mid-IR survey of the L 1641-N region with ISOCAM

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    We present an analysis of the L 1641 outflow region using broad-band and narrow-band imaging data at mid-infrared wavelengths from ISOCAM. We detect a total of 34 sources in the 7.657.65^{\prime} x 8.408.40^{\prime} region covered by the broad-band filters. Four of these sources have no reported detection in previous studies of the region. We find that the source previously identified as the near-IR counter-part to the IRAS detected point-source (IRAS 05338-0624) is not the brightest source in the wavelength region of the IRAS 12 \micron\ filter. We find instead that a nearby object (within the beam of IRAS and not detected at near-IR wavelengths) outshines all others sources in the area by a factor of \sim2. We submit that this source is likely to be the IRAS detected point source. A comparison of the near-IR (J-H vs H-K) and mid-IR (J-K vs [6.7 um]-[14 um]) color-color plots shows only four sources with excess emission at near-IR wavelengths, but atleast 85% of all sources show excess emission at mid-IR wavelengths. The CVF spectra suggest a range of evolutionary status in the program stars ranging from embedded YSOs to the young disks. When combined with optical and near-IR age estimates, these results show active current star-formation in the region that has been on-going for at least 2 Myr.Comment: Submitted to ApJ. Abstracted edited for arXiv submission Replaced by version accepted by Ap

    Non-factorizable Contributions to BππB \to \pi\pi Decays

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    We investigate to what extent the experimental information on BππB \to \pi\pi branching fractions and CP asymmetries can be used to better understand the QCD dynamics in these decays. For this purpose we decompose the independent isospin amplitudes into factorizable and non-factorizable contributions. The former can be estimated within the framework of QCD factorization for exclusive BB decays. The latter vanish in the heavy-quark limit, mbm_b \to \infty, and are treated as unknown hadronic parameters. We discuss at some length in which way the non-factorizable contributions are treated in different theoretical and phenomenological frameworks. We point out the potential differences between the phenomenological treatment of power-corrections in the ``BBNS approach'', and the appearance of power -suppressed operators in soft-collinear effective theory (SCET). On that basis we define a handful of different (but generic) scenarios where the non-factorizable part of isospin amplitudes is parametrized in terms of three or four unknowns, which can be constrained by data. We also give some short discussion on the implications of our analysis for BπKB \to \pi K decays. In particular, since non-factorizable QCD effects in BππB \to \pi \pi may be large, we cannot exclude sizeable non-factorizable effects, which violate SU(3)FSU(3)_F flavour symmetry, or even isospin symmetry (via long-distance QED effects). This may help to explain certain puzzles in connection with isospin-violating observables in BπKB \to \pi K decays.Comment: published version, minor correction

    Direct CP Violation, Branching Ratios and Form Factors BπB \to \pi, BKB \to K in BB Decays

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    The BπB \to \pi and BKB \to K transitions involved in hadronic B decays are investigated in a phenomenological way through the framework of QCD factorization. By comparing our results with experimental branching ratios from the BELLE, BABAR and CLEO Collaborations for all the B decays including either a pion or a kaon, we propose boundaries for the transition form factors BπB \to \pi and BKB \to K depending on the CKM matrix element parameters ρ\rho and η\eta. From this analysis, the form factors required to reproduce the experimental data for branching ratios are FBπ=0.31±0.12F^{B \to \pi}= 0.31 \pm 0.12 and FBK=0.37±0.13F^{B \to K}= 0.37\pm 0.13. We calculate the direct CP violating asymmetry parameter, aCPa_{CP}, for Bπ+ππB \to \pi^{+} \pi^{-} \pi and Bπ+πKB \to \pi^{+} \pi^{-} K decays, in the case where ρω\rho-\omega mixing effects are taken into account. Based on these results, we find that the direct CP asymmetry for Bπ+ππB^{-} \to \pi^{+} \pi^{-} \pi^{-}, Bˉ0π+ππ0\bar{B}^{0} \to \pi^{+} \pi^{-} \pi^{0}, Bπ+πKB^{-} \to \pi^{+} \pi^{-} K^{-}, and Bˉ0π+πKˉ0\bar{B}^{0} \to \pi^{+} \pi^{-} \bar{K}^{0}, reaches its maximum when the invariant mass π+π\pi^{+} \pi^{-} is in the vicinity of the ω\omega meson mass. The inclusion of ρω\rho-\omega mixing provides an opportunity to erase, without ambiguity, the phase uncertainty mod(π)(\pi) in the determination of the CKM angles α\alpha in case of bub\to u and γ\gamma in case of bsb \to s.Comment: 74 pages, 15 figures, 8 tables. A few misprints corrected, two references adde

    Symmetries and Asymmetries of B -> K* mu+ mu- Decays in the Standard Model and Beyond

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    The rare decay B -> K* (-> K pi) mu+ mu- is regarded as one of the crucial channels for B physics as the polarization of the K* allows a precise angular reconstruction resulting in many observables that offer new important tests of the Standard Model and its extensions. These angular observables can be expressed in terms of CP-conserving and CP-violating quantities which we study in terms of the full form factors calculated from QCD sum rules on the light-cone, including QCD factorization corrections. We investigate all observables in the context of the Standard Model and various New Physics models, in particular the Littlest Higgs model with T-parity and various MSSM scenarios, identifying those observables with small to moderate dependence on hadronic quantities and large impact of New Physics. One important result of our studies is that new CP-violating phases will produce clean signals in CP-violating asymmetries. We also identify a number of correlations between various observables which will allow a clear distinction between different New Physics scenarios.Comment: 56 pages, 18 figures, 14 tables. v5: Missing factor in eqs. (3.31-32) and fig. 6 corrected. Minor misprints in eq. (2.10) and table A corrected. Conclusions unchange

    Efficient synthesis of novel thieno[3,2-b]-, [2,3-c]- and [3,2-c]pyridones by Sonogashira coupling of bromothiophenes with terminal alkynes and subsequent intramolecular C-N bond-forming reaction

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    The coupling of bromothiophenes with terminal alkynes using triethylamine or diisopropyl amine under Sonogashira conditions (PdCl2(PPh 3)2, CuI) followed by subsequent addition of amines or ammonium to the intermediate thienyl acetylenes represents a novel access to a wide range of thieno[3,2-b]-, [2,3-c]-, and [3,2-c]pyridones under basic conditions and in excellent yields. © 2013 Elsevier Ltd. All rights reserved

    Charged-Lepton Flavour Physics

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    This writeup of a talk at the 2011 Lepton-Photon symposium in Mumbai, India, summarises recent results in the charged-lepton flavour sector. I review searches for charged-lepton flavour violation, lepton electric dipole moments and flavour-conserving CP violation. I also discuss recent progress in tau-lepton physics and in the Standard Model prediction of the muon anomalous magnetic moment.Comment: Presented at Lepton-Photon 2011, Mumbai, India; 23 pages, 14 figure

    BB-to-Glueball form factor and Glueball production in BB decays

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    We investigate transition form factors of BB meson decays into a scalar glueball in the light-cone formalism. Compared with form factors of BB to ordinary scalar mesons, the BB-to-glueball form factors have the same power in the expansion of 1/mB1/m_B. Taking into account the leading twist light-cone distribution amplitude, we find that they are numerically smaller than those form factors of BB to ordinary scalar mesons. Semileptonic BGlνˉB\to Gl\bar\nu, BGl+lB\to Gl^+l^- and BsGl+lB_s\to Gl^+l^- decays are subsequently investigated. We also analyze the production rates of scalar mesons in semileptonic BB decays in the presence of mixing between scalar qˉq\bar qq and glueball states. The glueball production in BcB_c meson decays is also investigated and the LHCb experiment may discover this channel. The sizable branching fraction in Bc(π+π)lνˉB_c\to (\pi^+\pi^-)l^-\bar\nu, Bc(K+K)lνˉB_c\to (K^+K^-)l^-\bar\nu or Bc(π+ππ+π)lνˉB_c\to (\pi^+\pi^-\pi^+\pi^-)l^-\bar\nu could be a clear signal for a scalar glueball state.Comment: 17 pages, 3 figure, revtex
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