38 research outputs found

    Implications of factorization for the determination of hadronic form factors in D_s^+ \ra \phi transition

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    Using factorization we determine the allowed domains of the ratios of form factors, x=A2(0)/A1(0)x = A_2(0)/A_1(0) and y=V(0)/A1(0)y = V(0)/A_1(0), from the experimentally measured ratio R_h \equiv \Gamma(D_s^+ \ra \phi \rho^+)/\Gamma(D_s^+ \ra \phi \pi^+) assuming three different scenarios for the q2q^2-dependence of the form factors. We find that the allowed domains overlap with those obtained by using the experimentally measured ratio R_{s\ell} = \Gamma(D^+_s \ra \phi \ell^+ \nu_{\ell})/\Gamma(D^+_s \ra \phi \pi^+) provided that the phenomenological parameter a1a_1 is 1.231.23. Such a comparison presents a genuine test of factorization. We calculate the longitudinal polarization fraction, \Gamma_L/\Gamma \equiv \Gamma(D_s^+ \ra \phi_L \rho^+_L)/\Gamma(D_s^+ \ra \phi \rho^+), in the three scenarios for the q2q^2-dependence of the form factors and emphasize the importance of measuring ΓL/Γ\Gamma_L/\Gamma . Finally we discuss the q2q^2-distribution of the semileptonic decay and find that it is rather insensitive to the scenarios for the q2q^2-dependence of the form factors, and unless very accurate data can be obtained it is unlikely to discriminate between the different scenarios. Useful information on the value of xx might be obtained by the magnitude of the q2q^2-distribution near q2=0q^2 = 0. However the most precise information on xx and yy would come from the knowledge of the longitudinal and left-right transverse polarizations of the final vector mesons in hadronic and/or semileptonic decays.Comment: Latex 10 pages( 4 figures), PAR/LPTHE/94-3

    On the Determination of a1a_1 and a2a_2 from Hadronic Two Body BB Decays

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    {}From Class I decays : B^o \ra \pi^+ ( \rho^+ ) + D^- ( {D^*}^- ), we determine a1a_1, and from Class III decays : B^+ \ra \pi^+ ( \rho^+ ) + \ol{D}^o ( {\ol{D}^*}^o ), we determine an allowed domain in the (a1,a2)( a_1, a_2 ) plane. We find that within one standard deviation errors, the allowed band of a1a_1 from Class I decays is at least three standard deviations removed from the allowed domain (a1,a2)( a_1, a_2 ) from Class III decays.If we expand the experimental errors to two standard deviations we do find a small intersection between the a1a_1 band and the allowed (a1,a2)( a_1, a_2 ) domain. The results usually quoted in the literature lie in this intersection. We suggest : (1) an independent measurement of the branching ratio for the Class III decay, B^+ \ra \rho^+ \ol{D}^o , (2) a high-statistics measurement of the branching ratio of the Class I decay, B \ra \ol{D} ( \ol{D}^* ) + D_s ( D_s^* ) in both charged states, and (3) a measurement of the longitudinal polarization fraction in the Class III decay B^+ \ra \rho^+ {\ol{D}^*}^o to shed more light on the questions involved .Comment: 9pages(Latex)+4 figures(PS file appended), PAR/LPTHE/94-2

    Superheavy Majorana neutrino effects in the lepton-number violating e- + e- -> mu- + mu- process

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    In the minimal extension of the standard electroweak theory with ultra massive Majorana neutrinos, the process e- + e- -> mu- + mu- could be observable, in sharp contrast with the reaction e- + e- -> W- + W- which is entirely controlled by neutrinoless double beta decay ββ0ν\beta \beta_{0 \nu} data. Our result provides the process background that must be confronted "new physics" models which postulate doubly charged particles, such as the gauge bilepton Y^{-} in the SU(3)c×SU(3)L×U(1)SU(3)_{\rm c} \times SU(3)_{\rm L} \times U(1) model, the left-right SU(2)L×SU(2)R×U(1)BLSU(2)_{\rm L} \times SU(2)_{\rm R} \times U(1)_{\rm B-L} one, and its supersymmetric version with doubly charged Higgs multiplets.Comment: 5 pages LaTeX + 1 postscript figure. Some references added; some new paragraphs added in the tex

    Nonfactorization and the decays Ds+ϕπ+,ϕρ+D_s^+ \to \phi \pi^+, \phi \rho^+ and ϕl+νl\phi l^+ \nu_l

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    In six chosen scenarios for the q2q^2 dependence of the form factors involved in Ds+ϕD_s^+ \rightarrow \phi transition, we have determined the allowed domain of x=A2(0)/A1(0)x = A_2(0) / A_1(0) and y=V(0)/A1(0)y = V(0)/A_1(0) from the experimentally measured ratios Rsl=Γ(Ds+ϕl+νl)/Γ(Ds+ϕπ+)R_{sl} = \Gamma(D_s^+ \rightarrow \phi l^+ \nu_l)/\Gamma(D_s^+ \rightarrow \phi \pi^+) and Rh=Γ(Ds+ϕρ+)/Γ(Ds+ϕπ+)R_h = \Gamma(D_s^+ \rightarrow \phi \rho^+)/\Gamma(D_s^+ \rightarrow \phi \pi^+) in a scheme that uses the Nc=3N_c =3 value of the phenomenological parameter a1a_1 and includes nonfactorized contribution. We find that the experimentally measured values of xx and yy from semileptonic decays of Ds+D_s^+ favor solutions which have significant nonfactorized contribution, and, in particular, RslR_{sl} favors solutions in scenarios where A1(q2)A_1(q^2) is either flat or decreasing with q2q^2.Comment: 15 pages, Latex, four figure (available on request)

    Hadronic Charmed Meson Decays Involving Axial Vector Mesons

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    Cabibbo-allowed charmed meson decays into a pseudoscalar meson and an axial-vector meson are studied. The charm to axial-vector meson transition form factors are evaluated in the Isgur-Scora-Grinstein-Wise quark model. The dipole momentum dependence of the DKD\to K transition form factor and the presence of a sizable long-distance WW-exchange are the two key ingredients for understanding the data of DKˉa1D\to \bar Ka_1. The K1AK1BK_{1A}-K_{1B} mixing angle of the strange axial-vector mesons is found to be ±37\approx \pm37^\circ or ±58\pm58^\circ from τK1ντ\tau\to K_1\nu_\tau decays. The study of DK1(1270)π,K1(1400)πD\to K_1(1270)\pi, K_1(1400)\pi decays excludes the positive mixing-angle solutions. It is pointed out that an observation of the decay D0K1(1400)π+D^0\to K_1^-(1400)\pi^+ at the level of 5×1045\times 10^{-4} will rule out θ37\theta\approx -37^\circ and favor the solution θ58\theta\approx -58^\circ. Though the decays D0Kˉ10π0D^0\to \bar K_1^0\pi^0 are color suppressed, they are comparable to and even larger than the color-allowed counterparts: Kˉ10(1270)π0K1(1270)π+\bar K_1^0(1270)\pi^0\sim K_1^-(1270)\pi^+ and Kˉ10(1400)π0>K1(1400)π+\bar K_1^0(1400)\pi^0> K_1^-(1400)\pi^+. The finite width effect of the axial-vector resonance is examined. It becomes important for a1(1260)a_1(1260) in particular when its width is near 600 MeV.Comment: 19 page

    Trans-ancestry genome-wide association study identifies 12 genetic loci influencing blood pressure and implicates a role for DNA methylation

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    We carried out a trans-ancestry genome-wide association and replication study of blood pressure phenotypes among up to 320,251 individuals of East Asian, European and South Asian ancestry. We find genetic variants at 12 new loci to be associated with blood pressure (P = 3.9 × 10-11 to 5.0 × 10-21). The sentinel blood pressure SNPs are enriched for association with DNA methylation at multiple nearby CpG sites, suggesting that, at some of the loci identified, DNA methylation may lie on the regulatory pathway linking sequence variation to blood pressure. The sentinel SNPs at the 12 new loci point to genes involved in vascular smooth muscle (IGFBP3, KCNK3, PDE3A and PRDM6) and renal (ARHGAP24, OSR1, SLC22A7 and TBX2) function. The new and known genetic variants predict increased left ventricular mass, circulating levels of NT-proBNP, and cardiovascular and all-cause mortality (P = 0.04 to 8.6 × 10-6). Our results provide new evidence for the role of DNA methylation in blood pressure regulation

    Production of Υ(nS) mesons in Pb+Pb and pp collisions at 5.02 TeV

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    A measurement of the production of vector bottomonium states, Υ ( 1S ) , Υ ( 2S ) , and Υ ( 3S ) , in Pb + Pb and p p collisions at a center-of-mass energy per nucleon pair of 5.02 TeV is presented. The data correspond to integrated luminosities of 1.38 nb − 1 of Pb + Pb data collected in 2018, 0.44 nb − 1 of Pb + Pb data collected in 2015, and 0.26 fb − 1 of p p data collected in 2017 by the ATLAS detector at the Large Hadron Collider. The measurements are performed in the dimuon decay channel for transverse momentum p μ μ T < 30 GeV , absolute rapidity | y μ μ | < 1.5 , and Pb + Pb event centrality 0–80%. The production rates of the three bottomonium states in Pb + Pb collisions are compared with those in p p collisions to extract the nuclear modification factors as functions of event centrality, p μ μ T , and | y μ μ | . In addition, the suppression of the excited states relative to the ground state is studied. The results are compared with theoretical model calculations

    Some problems with the hyperfine structure of charmonium

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