Rare charm meson decays D->Pl^+l^- and c->ul^+l^- in SM and MSSM

We study the nine possible rare charm meson decays D->Pl^+l^- (P=pi,K,eta,eta') using the Heavy Meson Chiral Lagrangians and find them to be dominated by the long distance contributions. The decay D^+ -> pi^+l^+l^- with the branching ratio 1*10^(-6) is expected to have the best chances for an early experimental discovery. The short distance contribution in the five Cabibbo suppressed channels arises via the c->ul^+l^- transition; we find that this contribution is detectable only in the D->pi l^+l^- decay, where it dominates the differential spectrum at high-q^2. The general Minimal Supersymmetric Standard Model can enhance the c->ul^+l^- rate by up to an order of magnitude; its effect on the D->Pl^+l^- rates is small since the c->ul^+l^- enhancement is sizable in low-q^2 region, which is inhibited in the hadronic decay.Comment: 17 page

Hard Instances of the Constrained Discrete Logarithm Problem

The discrete logarithm problem (DLP) generalizes to the constrained DLP, where the secret exponent $x$ belongs to a set known to the attacker. The complexity of generic algorithms for solving the constrained DLP depends on the choice of the set. Motivated by cryptographic applications, we study sets with succinct representation for which the constrained DLP is hard. We draw on earlier results due to Erd\"os et al. and Schnorr, develop geometric tools such as generalized Menelaus' theorem for proving lower bounds on the complexity of the constrained DLP, and construct sets with succinct representation with provable non-trivial lower bounds

Nonresonant Three-body Decays of D and B Mesons

Nonresonant three-body decays of D and B mesons are studied. It is pointed out that if heavy meson chiral perturbation theory (HMChPT) is applied to the heavy-light strong and weak vertices and assumed to be valid over the whole kinematic region, then the predicted decay rates for nonresonant charmless 3-body B decays will be too large and especially B^- --> pi^- K^+ K^- greatly exceeds the current experimental limit. This can be understood as chiral symmetry has been applied there twice beyond its region of validity. If HMChPT is applied only to the strong vertex and the weak transition is accounted for by the form factors, the dominant B^* pole contribution to the tree-dominated direct three-body B decays will become small and the branching ratio will be of order 10^{-6}. The decay modes B^- --> (K^- h^+ h^-)_{NR} and bar{B}^0 --> (bar{K}^0 h^+h^-)_{NR} for h = pi, K are penguin dominated. We apply HMChPT in two different cases to study the direct 3-body D decays and compare the results with experiment. Theoretical uncertainties are discussed.Comment: 24 pages, 2 figures. New experimental results of direct 3-body D decays as Reported at ICHEP2002 are included. To appear in Phys. Re

Radiative tau decay and the magnetic moment of the muon

We discuss the decay tau^- -> nu_tau pi^- pi^0 gamma in terms of a model with the correct low-energy structure and with the relevant resonance degress of freedom. The nontrivial radiative dynamics becomes visible for large photon momenta only. We use the model to calculate electromagnetic corrections for the two-pion contribution to hadronic vacuum polarization extracted from photon-inclusive two-pion decays. The corrections are insensitive to the details of the model and depend on the pion form factor only. Putting all relevant isospin violating corrections together, we obtain a shift Delta a_mu = (- 120 +/- 26 +/- 3) x 10^-11 to be applied to determinations of the anomalous magnetic moment of the muon from photon-inclusive tau data.Comment: 24 pages, 6 figure

Treatable traits in the European U-BIOPRED adult asthma cohorts

No abstract availabl

Rare Charm Decays in the Standard Model and Beyond

We perform a comprehensive study of a number of rare charm decays, incorporating the first evaluation of the QCD corrections to the short distance contributions, as well as examining the long range effects. For processes mediated by the $c\to u\ell^+\ell^-$ transitions, we show that sensitivity to short distance physics exists in kinematic regions away from the vector meson resonances that dominate the total rate. In particular, we find that $D\to\pi\ell^+\ell^-$ and $D\to\rho\ell^+\ell^-$ are sensitive to non-universal soft-breaking effects in the Minimal Supersymmetric Standard Model with R-parity conservation. We separately study the sensitivity of these modes to R-parity violating effects and derive new bounds on R-parity violating couplings. We also obtain predictions for these decays within extensions of the Standard Model, including extensions of the Higgs, gauge and fermion sectors, as well as models of dynamical electroweak symmetry breaking.Comment: 45 pages, typos fixed, discussions adde

Vector meson production and nucleon resonance analysis in a coupled-channel approach for energies m_N < sqrt(s) < 2 GeV II: photon-induced results

We present a nucleon resonance analysis by simultaneously considering all pion- and photon-induced experimental data on the final states gamma N, pi N, 2 pi N, eta N, K Lambda, K Sigma, and omega N for energies from the nucleon mass up to sqrt(s) = 2 GeV. In this analysis we find strong evidence for the resonances P_{31}(1750), P_{13}(1900), P_{33}(1920), and D_{13}(1950). The omega N production mechanism is dominated by large P_{11}(1710) and P_{13}(1900) contributions. In this second part we present the results on the photoproduction reactions and the electromagnetic properties of the resonances. The inclusion of all important final states up to sqrt(s) = 2 GeV allows for estimates on the importance of the individual states for the GDH sum rule.Comment: 41 pages, 26 figures, discussion extended, typos corrected, references updated, to appear in Phys. Rev.

SU(3)c⊗SU(3)L⊗U(1)x as an SU(6)⊗U(1)x subgroup

ABSTRACT: An extension of the standard model to the local gauge group SU(3) c ^ SU(3)L ^ U(1)X as a family independent model is presented. The mass scales, the gauge boson masses, and the masses for the spin 1/2 particles in the model are studied. The mass differences between the up and down quark sectors, between the quarks and leptons, and between the charged and neutral leptons in one family are analyzed. The existence of two Dirac neutrinos for each family, one light and one very heavy, is predicted. By using experimental results from CERN LEP, SLC and atomic parity violation we constrain the mixing angle between the two neutral currents and the mass of the additional neutral gauge boson to be 20.00015<sin u<0 and 1.5 TeV<MZ2 at 95% C.L