1,841 research outputs found

    Photon polarization in radiative B decays

    Full text link
    We study decay distributions in B -> K pi pi gamma, combining contributions from several overlapping resonances in a K pi pi mass range near 1400 MeV, (1^+) K_1(1400), (2^+) K^*_2(1430) and (1^-) K^*(1410). A method is proposed for using these distributions to determine a photon polarization parameter in the effective radiative weak Hamiltonian. This parameter is measured through an up-down asymmetry of the photon direction relative to the K pi pi decay plane. We calculate a dominant up-down asymmetry of 0.33 +- 0.05 from the K1(1400) resonance, which can be measured with about 10^8 B B-bar pairs, thus providing a new test for the Standard Model and a probe for some of its extensions.Comment: 22 pages, 3 figures, version to appear in Phys. Rev.

    Form factors of heavy-to-light B decays at large recoil

    Get PDF
    General relations between the form factors of B decays to light mesons are derived using the heavy quark and large recoil expansion. On their basis the complete account of contributions of second order in the ratio of the light meson mass to the large recoil energy is performed. Both ground and excited final meson states are considered. It is shown that most of the known form factor relations remain valid after the inclusion of quadratic mass corrections. The validity of some of such relations requires additional equalities for the helicity amplitudes. It is found that all these relations and equalities are fulfilled in the relativistic quark model based on the quasipotential approach in quantum field theory. The contribution of 1/m_b corrections to the branching fraction of the rare radiative B decay is discussed.Comment: 23 pages, revte

    An Optimal Self-Stabilizing Firing Squad

    Full text link
    Consider a fully connected network where up to tt processes may crash, and all processes start in an arbitrary memory state. The self-stabilizing firing squad problem consists of eventually guaranteeing simultaneous response to an external input. This is modeled by requiring that the non-crashed processes "fire" simultaneously if some correct process received an external "GO" input, and that they only fire as a response to some process receiving such an input. This paper presents FireAlg, the first self-stabilizing firing squad algorithm. The FireAlg algorithm is optimal in two respects: (a) Once the algorithm is in a safe state, it fires in response to a GO input as fast as any other algorithm does, and (b) Starting from an arbitrary state, it converges to a safe state as fast as any other algorithm does.Comment: Shorter version to appear in SSS0

    Possible Supersymmetric Effects on Angular Distributions in BK(Kπ)+B \to K^* (\to K \pi) \ell^+ \ell^- Decays

    Full text link
    We investigate the angular distributions of the rare B decay, BK(Kπ)+B \to K^* (\to K \pi) \ell^+ \ell^-, in general supersymmetric extensions of the standard model. We consider the new physics contributions from the operators O7,8,9,10O_{7,8,9,10} in small invariant mass region of lepton pair. We show that the azimuthal angle distribution of the decay can tell us the new physics effects clearly from the behavior of the distribution, even if new physics does not change the decay rate substantially from the standard model prediction

    Measuring the Photon Helicity in Radiative B Decays

    Full text link
    We propose a way of measuring the photon polarization in radiative B decays into K resonance states decaying to K\pi\pi, which can test the Standard Model and probe new physics. The photon polarization is shown to be measured by the up-down asymmetry of the photon direction relative to the K\pi\pi decay plane in the K resonance rest frame. The integrated asymmetry in K_1(1400)\to K\pi\pi, calculated to be 0.34\pm 0.05 in the Standard Model, is measurable at currently operating B factories.Comment: 4 pages, final version to appear in Physical Review Letter

    1/m_Q Corrections to the Heavy-to-Light-Vector Transitions in the HQET

    Full text link
    Within the HQET, the heavy to light vector meson transitions are systematically analyzed to the order of 1/m_Q. Besides the four universal functions at the leading order, there are twenty-two independent universal form factors at the order of 1/m_Q. Both the semileptonic decay B->\rho which is relevant to the |V_{ub}| extraction, and the penguin induced decay B -> K^* which is important to new physics discovering, depend on these form factors. Phenomenological implications are discussed.Comment: RevTeX, 9 pages, no figure

    Rare radiative B decay to the orbitally excited K_2^*(1430) meson

    Get PDF
    The exclusive rare radiative B meson decay to the orbitally excited tensor K_2^*(1430) meson is investigated in the framework of the relativistic quark model based on the quasipotential approach in quantum field theory. The calculated branching ratio BR(B --> K_2^*(1430)\gamma)=(1.7\pm 0.6)\times 10^{-5} as well as the ratio BR(B --> K_2^*(1430)\gamma)/BR(B --> K^*(892)\gamma)=0.38\pm 0.08 is found in a good agreement with recent experimental data from CLEO.Comment: 10 pages, RevTe

    Emotional responses shape the substance of information seeking under conditions of threat

    Get PDF
    This is the author accepted manuscript. The final version is available from SAGE Publications via the DOI in this recordMenacing news inclines individuals to acquire information, and research has explored how emotional reactions such as fear or anger condition this process. While scholars have debated the relevance of fear and anger for levels of attentiveness and learning in politics, fewer studies consider how variation in emotional responses can shape the substance of information searches in times of threat.We posit that heightened fear motivates interest in defense-oriented information among threatened individuals, while heightened anger motivates interest in aggression-oriented information. To test these hypotheses, we focus on international terrorist threat because of its known tendency to elevate both anger and fear. We use data that permit a behavioral measure of information seeking, via an experiment embedded within a dynamic process tracing environment (DPTE) platform. Within this information-rich context, exposure to terrorist threat motivates a search for relevant information. Further, we find that while an induction to elevate anger prompts more immediate attention to aggression-oriented information, an induction to elevate fear is more effective in steering attention toward defense-oriented information
    corecore