134,313 research outputs found
Ultrahigh Energy Tau Neutrinos
We study ultrahigh energy astrophysical neutrinos and the contribution of tau
neutrinos from neutrino oscillations, relative to the contribution of the other
flavors. We show the effect of tau neutrino regeneration and tau energy loss as
they propagate through the Earth. We consider a variety of neutrino fluxes,
such as cosmogenic neutrinos and neutrinos that originate in Active Galactic
Nuclei. We discuss signals of tau neutrinos in detectors such as IceCube, RICE
and ANITA.Comment: Invited talk given at the ``8th Workshop on Non-Perturbative Quantum
Chromodynamics", June 7-11, 2004, Paris, France; 10 pages, 6 figure
Beauty hadron lifetime ratios and the problem of
We describe a theoretical approach to compute inclusive widths of heavy
hadrons, based on a systematic expansion in the inverse powers of the heavy
quark mass. The method reproduces quite well the experimental ratios of
mesons lifetimes. As for , we present a QCD sum rule
calculation of the contribution to ; we conclude
that such correction is not responsible of the small experimental value of
.Comment: Talk presented at the Fifth Topical Seminar on The Irresistible Rise
of the Standard Model, San Miniato, Italy, April 21-25, 1997. Latex, 4 pages,
1 figur
Charged Higgs boson contribution to for very large in the two Higgs doublet model with UHE-neutrinos
We study the deep inelastic process
(with an isoscalar nucleon), in the context of the
two Higgs doublet model {\it type two} (2HDM(II)). In particular, we discuss
the contribution to the total cross section of diagrams, in which a charged
Higgs boson is exchanged. We show that for large values of such
contribution for an inclusive dispersion generated through the collision of an
ultrahigh energy tau-neutrino on a target nucleon can reach up to 57% of the
value of the contribution of the exchange diagrams (i.e. can reach up to
57% of the standard model (SM) prediction) and could permit to distinguish
between the SM and the 2HDM(II) predictions at the Pierre Auger Observatory.Comment: 10 pages, 5 figure
Resonant Structure of and Decays
The resonant structure of the four pion final state in the decay is analyzed using 4.27 million pairs
collected by the CLEO II experiment. We search for second class currents in the
decay using spin-parity analysis and establish an
upper limit on the non-vector current contribution. The mass and width of the
resonance are extracted from a fit to the
spectral function. A partial wave analysis of the resonant structure of the
decay is performed; the spectral decomposition of
the four pion system is dominated by the and final
states.Comment: 34 pages postscript, also available through
http://w4.lns.cornell.edu/public/CLN
The Contribution of Bc Mesons to the Search for B->tau nu Decays at LEP
We study the contribution of B_c mesons to the search for B->tau nu decays.
We find that at LEP the contributions from B_u and B_c mesons can be
comparable. This observation can have a relevant impact on the extraction of
constraints on new physics (such as charged-Higgs contributions) from current
LEP limits on B->tau nu final states. Inclusion of the B_c contribution can
reduce the current L3 limit on Tan(beta)/M_H from 0.38/GeV (90%CL) down to
0.27/GeV (90%CL).Comment: 8 pages, Latex, epsfig, 1 figur
Review of Recent Calculations of the Hadronic Vacuum Polarisation Contribution
Recent calculations of the hadronic vacuum polarisation contribution are
reviewed. The focus is put on the leading-order contribution to the muon
magnetic anomaly involving annihilation cross section data as input to
a dispersion relation approach. Alternative calculation including tau data is
also discussed. The data are corrected for various isospin-breaking
sources which are explicitly shown source by source.Comment: 8 pages, 9 figures, 3 tables, invited talk given at the FCCP 2015
worksho
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