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Consequences of unitarity and analyticity for weak interactions

Description: One considers the implications of the fact that weak two body scattering amplitudes, when calculated to all orders in any renormalizable model, should exhibit unitary, analytic, ''Mandelstam'' behavior. One discusses from this point of view, the existence of neutral currents, the suppression of $nu$/sub $mu$/e elastic scattering, and the possibility of lepton hadron resonances. A brief review is given of the predictions for lepton--lepton scattering of two models in which Mandelstam behavior is explicitly realized. (auth)
Date: January 1975
Creator: Dicus, D. A. & Teplitz, V. L.
Partner: UNT Libraries Government Documents Department

Production of pseudoscalar Higgs-bosons in e {gamma} collisions

Description: We investigate the production of a pseudoscalar Higgs-boson A{sup 0} using the reaction e{gamma} {yields} e A{sup 0} at an e{bar e} collider with center of mass energy of 500 GeV. Supersymmetric contributions are included and provide a substantial enhancement to the cross section for most values of the symmetry breaking parameters. We find that, despite the penalty incurred in converting one of the beams into a source of backscattered photons, the e{gamma} process is a promising channel for the detection of the A{sup 0}.
Date: August 21, 1995
Creator: Dicus, D.A. & Repko, W.W.
Partner: UNT Libraries Government Documents Department

Radiative corrections to the decays K{sub L}{sup 0} {r_arrow} e{sup +}e{sup {minus}} and K{sub L}{sup 0} {r_arrow} {mu}{sup +} {mu}{sup {minus}}

Description: The authors calculate the rates and lepton ({ell}) invariant mass distributions for decays of the form 0{sup {minus}+} {r_arrow} {ell}{sup +}{ell}{sup {minus}}{gamma}, which are important radiative corrections to the purely leptonic decays 0{sup {minus}+} {r_arrow} {ell}{sup +}{ell}{sup {minus}}. The approach uses the loop diagrams which arise by including the two photon intermediate state and they retain the imaginary parts of the loops--a radiative extension of the unitarity bound for the process. These results are compared with those obtained using a model in which the meson couples directly to the leptons.
Date: December 31, 1998
Creator: Dicus, D.A. & Repko, W.W.
Partner: UNT Libraries Government Documents Department

Photon-neutrino interactions

Description: The cross sections for the processes {gamma}{nu} {yields} {gamma}{gamma} {yields} {nu}{anti {nu}} are calculated with the aid of an effective Lagrangian derived from the Standard model. These cross sections are shown to be much larger than the elastic cross section {sigma}({gamma}{nu} {yields} {gamma}{nu}) for photon energies {omega} {ge} 1 keV. Possible astrophysical implications are discussed.
Date: December 1, 1997
Creator: Dicus, D.A. & Repko, W.W.
Partner: UNT Libraries Government Documents Department

High energy photon-neutrino interactions

Description: A general decomposition of the amplitudes for the 2 {r_arrow} 2 processes {gamma}{nu} {r_arrow} {gamma}{nu} and {gamma}{gamma} {r_arrow} {nu}{bar {nu}} is obtained using gauge invariance and Bose symmetry. The restrictions implied by this decomposition are investigated for the reaction {gamma}{gamma} {r_arrow} {nu}{bar {nu}} by computing the one-loop helicity amplitudes in the standard model. In the center of mass, where {radical}s = 2{omega}, the cross section grows roughly as {omega}{sup 6} up to the threshold for W-boson production, {radical}s = 2m{sub W}. Astrophysical implications of very high energy photon-neutrino interactions are discussed.
Date: July 14, 1998
Creator: Abbasabadi, A.; Devoto, A.; Dicus, D.A. & Repko, W.W.
Partner: UNT Libraries Government Documents Department

Corrections to primordial nucleosynthesis

Description: The changes in primordial nucleosynthesis resulting from small corrections to rates for weak processes that connect neutrons and protons are discussed. The weak rates are corrected by improved treatment of Coulomb and radiative corrections, and by inclusion of plasma effects. The calculations lead to a systematic decrease in the predicted /sup 4/He abundance of about ..delta..Y = 0.0025. The relative changes in other primoridal abundances are also 1 to 2%.
Date: January 1, 1982
Creator: Dicus, D.A.; Kolb, E.W.; Gleeson, A.M.; Sudarshan, E.C.G.; Teplitz, V.L. & Turner, M.S.
Partner: UNT Libraries Government Documents Department

Research program in particle physics

Description: This report discusses the following topics: Quantum Gravity and Mathematical Physics; Phenomenology; Quantum Mechanics and Quantum Field Theory; Status of BNL Expt. 791; BNL Expt. 791; BNL Expt. 888; and SSC Activities.
Date: July 1, 1992
Creator: Sudarshan, E.C.G.; Dicus, D.A.; Ritchie, J.L. & Lang, K.
Partner: UNT Libraries Government Documents Department

Supernova constraints on a superlight gravitino

Description: In supergravity models with low supersymmetry breaking scale the gravitinos can be superlight, with mass in the 10{sup -6} eV to few keV range. In such a case, gravitino emission provides a new cooling mechanism for protoneutron stars and therefore can provide constraints on the mass of a superlight gravitino. This happens because the coupling to matter of superlight gravitinos is dominated by its goldstino component, whose coupling to matter of superlight gravitinos is dominated by its goldstino component, whose coupling to matter is inversely proportional to the scale of supersymmetry breaking and increases as the gravitino mass decreases. Present observations therefore provide lower limits on the gravitino mass. Using the recently revised goldstino couplings, we find that the two dominant processes in supernova cooling are e{sup +} e{sup -} {yields} GG and {gamma}+e{sup -} {yields} e{sup -} GG. They lead to a lower limit on the supersymmetry breaking scale {Lambda}{sub s} from 160 to 500 GeV for core temperatures 30 to 60 MeV and electron chemical potentials 200 to 300 MeV. The corresponding lower limits on the gravitino mass are .6 - 6 x 10{sup -6} eV.
Date: October 1, 1997
Creator: Dicus, D. A.; Mohapatra, R. N. & Teplitz, V. L.
Partner: UNT Libraries Government Documents Department

Radiative higgs boson decays H {yields} f{anti f}{gamma}

Description: Higgs boson radiative decays of the form H {r_arrow} f{ovr f}{gamma} are calculated in the Standard Model using the complete one-loop expressions for the decay amplitudes. Contributions to the radiative width from leptons and light quarks are given. We also present e{ovr e} invariant mass distributions for H {r_arrow} e{ovr e}{gamma}, which illustrate the importance of the photon pole contribution and the effects of the box diagrams. 4 refs., 6 figs.
Date: October 10, 1996
Creator: Abbasabadi, A.; Bowser-Chao, D.; Repko, W.W. & Dicus, D.A.
Partner: UNT Libraries Government Documents Department

Higgs-photon associated production at hadron colliders

Description: The authors present cross sections for the reactions p{anti p} {yields} H{gamma} and pp {yields} H{gamma} arising from the subprocess q{anti q} {yields} H{gamma}. The calculation includes the complete one-loop contribution from all light quarks and is the main source of Higgs-photon associated production in hadron colliders. At Tevatron energies, the cross section is typically 0.1 fb or less, while at LHC energies it can exceed 1.0fb.
Date: November 1, 1997
Creator: Abbasabadi, A.; Bowser-Chao, D.; Dicus, D.A. & Repko, W.W.
Partner: UNT Libraries Government Documents Department