arXiv subjects

Wayne W. Repko

Publications and source records attributed to Wayne W. Repko.

68 records · Page 4Linked to original sources

arXiv1998

Effective Lagrangians and low energy photon-photon scattering

We use the behavior of the photon-photon scattering for photon energies $ω$ less than the electron mass, $m_e$, to examine the implications of treating the Euler-Heisenberg Lagrangian as an effective field theory. Specifically, we determine the $ω^2/m_e^2$ behavior of the scattering amplitude predicted by including one-loop corrections to the Euler-Heisenberg effective Lagrangian together with the counterterms required by renomalizability. This behavior is compared with the energy dependence obtained by expanding the exact QED photon-photon scattering amplitude. If the introduction of counterterms in the effective field theory is restricted to those determined by renormalizability, the $ω^2/m_e^2$ dependences of the two expansions differ.

hep-ph↗

arXiv1997

Probing Anomalous Higgs Coupling through mu+ mu- --> H gamma

The process mu+ mu- --> H gamma, though small compared to the resonance process, could be observable at proposed muon colliders, given expected integrated luminosities. The apparently leading diagrams occur at tree-level, and are proportional to the Higgs-muon coupling. We show, however, that the one-loop contribution is comparable to the tree-level amplitude. Furthermore, the one-loop diagrams, unlike those at tree-level, could be greatly enhanced by possible anomalous Higgs-top quark or Higgs-gauge boson couplings. For a 500 GeV unpolarized muon collider, the total cross section for H-gamma associated production approaches 0.1 fb.

hep-ph↗

arXiv1997

Production of neutral scalar Higgs bosons at $eγ$ colliders

We study the production of neutral scalar (CP even) Higgs bosons in the process $eγ\to e h$ by including supersymmetric corrections to the dominant $t$-channel photon exchange amplitude. In addition to the standard model $W^{\pm}$ and fermion loops, there are substantial contributions from chargino loops. For some cases, these contributions can exceed those of the $W$'s and ordinary fermions. The cross sections in this channel are generally one or two orders of magnitude larger than those in the related channel $e\bar{e}\toγh$.

hep-ph↗

arXiv1997

Photon-neutrino interactions

The cross sections for the processes γν--> γγν, γγ-->γν\barν and ν\barν -->γγγare 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 σ(γν--> γν) for photon energies $ω> 1$ keV. Possible astrophysical implications are discussed.

hep-ph↗

arXiv1996

Radiative Higgs Boson Decays H -> f fbar gamma

Higgs boson radiative decays of the form $H\rightarrow f\bar{f}γ$ 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 $e\bar{e}$ invariant mass distributions for $H\rightarrow e\bar{e}γ$, which illustrate the importance of the photon pole contribution and the effects of the box diagrams.

hep-ph↗

arXiv1996

Relativistic two-photon and two-gluon decay rates of heavy quarkonia

The decay rates of $c\bar{c}$ and $b\bar{b}$ through two-photon or two-gluon annihilations are obtained by using totally relativistic decay amplitudes and a sophisticated quantum-chromodynamic potential model for heavy quarkonia. Our results for the photonic and gluonic widths of the 1S0, 3P0, and the 3P2 states are in excellent agreement with the available experimental data. The procedures and mathematical techniques used by us for the treatment of the fermion-antifermion bound states are also applicable to other decay processes.

hep-ph↗

arXiv1996

Gauge-boson scattering signals at the LHC

We have extended our earlier treatment of the gauge-boson scattering with radiative corrections in the standard model at supercollider energies, and computed the rates for gauge-boson scattering modes in $pp$ collisions leading to the final states $W^+W^-$, $ZZ(4l)$, $ZZ(2l2ν)$, $W^\pm Z$, and $W^\pm W^\pm $. Our results at the LHC \hbox{energy} of $\sqrt{s}=14$~TeV for $m_H=1000$~GeV are compared with those recently obtained by Bagger {\it et al.} These results will be useful in the search for the Higgs bosons at supercollider energies as well as for experimentally distinguishing the standard model from non-minimal Higgs models.

hep-ph↗

arXiv1996

Production of pseudoscalar Higgs-bosons in $e\,γ$ collisions

We investigate the production of a pseudoscalar Higgs-boson $A^0$ using the reaction $e\,γ\rightarrow e\,A^0$ 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 $e\, γ$ process is a promising channel for the detection of the $A^0$.

hep-ph↗

arXiv1995

Higgs-photon associated production at $e\bar{e}$ colliders

We present complete analytical expressions for the amplitudes of the process $e\bar{e}\rightarrow Hγ$. The calculation is performed using nonlinear gauges, which significantly simplifies both the actual analytical calculation and the check of its gauge invariance. After comparing our results with a previous numerical calculation, we extend the range of Higgs masses and center of mass energies to those appropriate to LEP 200 and a future linear collider.

hep-ph↗

arXiv1993

Heavy Quarkonium Potential Model and the ${}^1P_1$ State of Charmonium

A theoretical explanation of the observed splittings among the P~states of charmonium is given with the use of a nonsingular potential model for heavy quarkonia. We also show that the recently observed mass difference between the center of gravity of the ${}^3P_J$ states and the ${}^1P_1$ state of $c\bar{c}$ does not provide a direct test of the color hyperfine interaction in heavy quarkonia. Our theoretical value for the mass of the ${}^1P_1$ state is in agreement with the experimental result, and its E1 transition width is 341.8~keV. The mass of the $η_c'$ state is predicted to be 3622.3~MeV.

hep-ph↗

arXiv1993

W, Z and Higgs Scattering at SSC Energies

The scattering of $W$, $Z$ and Higgs bosons in the Standard Model is investigated in the region $s,m_H^2\gg m_W^2$ with no restrictions on relative sizes of $s$ and $m_H^2$, so that our results are applicable at energies below as well as above $2m_H$. We have calculated, with the inclusion of the full one-loop corrections, the scattering matrix between the states $W_L^+W_L^-$, $Z_LZ_L$ and $HH$, and computed the S-wave amplitudes as functions of the center-of-mass energy $\sqrt{s}$ for $m_H=$500~GeV and 1000~GeV. The apparent violation of unitarity is avoided by unitarizing the amplitudes by the K-matrix and the Padé methods. For the detection of the Higgs boson through gauge boson scattering in $pp$ collisions, we have used the unitarized amplitudes to obtain the invariant-mass distributions for the final $W_L^+W_L^-$ and $Z_LZ_L$ pairs at the SSC energy of $\sqrt{s}=$40~TeV by means of the effective-W approximation.

hep-ph↗

arXiv1993

Photon neutrino scattering

The cross section for photon neutrino scattering is calculated in the standard model assuming that the neutrino is massless and that the center of mass energy is small compared to any charged lepton mass. Although the scattered photons can acquire a (parity violating) circular polarization of order unity, the cross section in this limit is highly suppressed.

hep-ph↗

arXiv1993

W, Z and Higgs Scattering at SSC Energies

We examine the scattering of longitudinal $W$, $Z$ and Higgs bosons in the Standard Model using the equivalent Goldstone-boson Lagrangian. Our calculations include the full one-loop scattering matrix between the states $W^+_LW^-_L$, $Z_LZ_L$ and $HH$ with no restrictions on the relative sizes of $M_H$ and $\sqrt{s}$. In addition to deriving the perturbative eigen-amplitudes, we also obtain quite striking results by unitarizing the amplitudes with the use of the K-matrix and Padé techniques. (Complete postscript file can be obtained by anonymous ftp from hal.physics.wayne.edu as dpf92g.ps in directory pub/physics )

hep-ph↗

arXiv1993

The effects of a strongly interacting Higgs sector on $γ\,γ\rightarrow W_L^+\,W_L^-, Z_L^{\,0}\,Z_L^{\,0}$ scattering

We study the effects of a strongly interacting Higgs sector on the amplitudes for $γ\,γ\rightarrow W_L^+\,W_L^-, Z_L^{\,0}\,Z_L^{\,0}$ by unitarizing the $W_L^+\,W_L^-, Z_L^{\,0}\,Z_L^{\,0}, γ\,γ$ system using the $K$--matrix technique. Unitarization produces substantial corrections to the cross sections for gauge boson pair production by photon fusion when $m_H \agt 5-10\;$TeV.

hep-ph↗