5,831 research outputs found

    Factorization in B -> K pi e+e- decays

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    We derive factorization relations for the transverse helicity amplitudes in the rare decays B-> K\pi l+l- at leading order in Lambda/m_b, in the kinematical region with an energetic kaon and a soft pion. We identify and compute a new contribution of leading order in Lambda/m_b to the B->K\pi l+l- amplitude, which is not present in the one-body decay B-> K*l+l-. As an application we study the forward-backward asymmetry (FBA) of the lepton momentum angular distribution in B-> K\pi l+l- decays away from the K* resonance. The FBA in these decays has a zero at q0^2 = q0^2(M_{Kpi}), which can be used, in principle, for determining the Wilson coefficients C_{7,9} and testing the Standard Model. We point out that the slope of the q0^2(M_{Kpi}^2) curve contains the same information about the Wilson coefficients as the location of the zero, but is less sensitive to unknown nonperturbative dynamics. We estimate the location of the zero at leading order in factorization, and using a resonant model for the B -> K\pi l+l- nonfactorizable amplitude.Comment: 16 pages, 5 figures. Version to appear in Physical Review D. One new observable introduced and considered - the slope of the zero of the forward-backward asymmetry as function of the K\pi invariant mas

    Heavy Meson Physics: What have we learned in Twenty Years?

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    I give a personal account of the development of the field of heavy quarks. After reviewing the experimental discovery of charm and bottom quarks, I describe how the field's focus shifted towards determination of CKM elements and how this has matured into a precision science.Comment: This talk was presented during the ceremony awarding the Medalla 2003 of the Division of Particles and Fields of The Mexican Phsyical Society, at the IX Mexican Workshop on Particles and Fields; submitted for proceedings; 9 pages, 9 figures; replacement: fix multiple typo

    Lepton non-universality in BB decays and fermion mass structure

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    We consider the possibility that the neutral-current BB anomalies are due to radiative corrections generated by Yukawa interactions of quarks and leptons with new vector-like quark and lepton electroweak doublets and new Standard Model singlet scalars. We show that the restricted interactions needed can result from an underlying Abelian family symmetry and that the same symmetry can give rise to an acceptable pattern of quark and charged lepton masses and mixings, providing a bridge between the non-universality observed in the B-sector and that of the fermion mass matrices. We construct two simple models, one with a single singlet scalar in which the flavour changing comes from quark and lepton mixing and one with an additional scalar in which the flavour changing can come from both fermion and scalar mixing. We show that for the case the new quarks are much heavier than the new leptons and scalars the BB anomalies can be due to box diagrams with couplings in the perturbative regime consistent with the bounds coming from Bs−BˉsB_s- \bar B_s, K−KˉK- \bar K and D−DˉD- \bar D mixing as well as other lepton family number violating processes. The new states can be dark matter candidates and, in the two scalar model with a light scalar of O(60) GeV and vector-like lepton of O(100) GeV, there can be a simultaneous explanation of the B-anomalies, the muon anomalous magnetic moment and the dark matter abundance.Comment: Replacement contains few additional reference

    The Lee-Wick Standard Model

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    We construct a modification of the standard model which stabilizes the Higgs mass against quadratically divergent radiative corrections, using ideas originally discussed by Lee and Wick in the context of a finite theory of quantum electrodynamics. The Lagrangian includes new higher derivative operators. We show that the higher derivative terms can be eliminated by introducing a set of auxiliary fields; this allows for convenient computation and makes the physical interpretation more transparent. Although the theory is unitary, it does not satisfy the usual analyticity conditions.Comment: 20 pages, 4 figures. Improved discussion and reference added. Contour prescription clarifie

    Massive Vector Scattering in Lee-Wick Gauge Theory

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    We demonstrate that amplitudes describing scattering of longitudinally polarized massive vector bosons present in non-Abelian Lee-Wick gauge theory do not grow with energy and, hence, satisfy the constraints imposed by perturbative unitarity. This result contrasts with the widely-known violation of perturbative unitarity in the standard model with a very heavy Higgs. Our conclusions are valid to all orders of perturbation theory and depend on the existence of a formulation of the theory in which all operators are of dimension four or less. This can be thought of as a restriction on the kinds of higher dimension operator which can be included in the higher derivative formulation of the theory.Comment: 11 pages, no figure

    Magnetic Wormholes and Vertex Operators

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    We consider wormhole solutions in 2+12+1 Euclidean dimensions. A duality transformation is introduced to derive a new action from magnetic wormhole action of Gupta, Hughes, Preskill and Wise. The classical solution is presented. The vertex operators corresponding to the wormhole are derived. Conformally coupled scalars and spinors are considered in the wormhole background and the vertex operators are computed. ( To be published in Phys. Rev. D15)Comment: 18 pages of RevTex, preprint IP/BBSR/94-2

    Operator Product Expansion for Exclusive Decays: B^+ ->Ds^+ e+e- and B^+ -> Ds^{*+} e+e-

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    The decays B+→Ds,d+e+e−B^+\to D_{s,d}^+e^+e^- and B+→Ds,d∗+e+e−B^+\to D_{s,d}^{*+}e^+e^- proceed through a weak and an electromagnetic interaction. This is a typical ``long distance'' process, usually difficult to compute systematically. We propose that over a large fraction of phase space a combination of an operator product and heavy quark expansions effectively turns this process into one in which the weak and electromagnetic interactions occur through a local operator. Moreover, we use heavy quark spin symmetry to relate all the local operators that appear in leading order of the operator expansion to two basic ones. We use this operator expansion to estimate the decay rates for B+→Ds,d(∗)+e+e−B^+\to D_{s,d}^{(*)+}e^+e^-.Comment: 4 pages, 1 figure, Latex, published version in PR
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