arXiv subjects

W. W. Repko

Publications and source records attributed to W. W. Repko.

6 recordsLinked to original sources

arXiv2009

Strange Quarks Nuggets in Space: Charges in Seven Settings

We have computed the charge that develops on an SQN in space as a result of balance between the rates of ionization by ambient gammas and capture of ambient electrons. We have also computed the times for achieving that equilibrium and binding energy of the least bound SQN electrons. We have done this for seven different settings. We sketch the calculations here and give their results in the Figure and Table II; details are in the Physical Review D.79.023513 (2009).

astro-ph.HE↗

arXiv2008

Charges on Strange Quark Nuggets in Space

Since Witten's seminal 1984 paper on the subject, searches for evidence of strange quark nuggets (SQNs) have proven unsuccessful. In the absence of experimental evidence ruling out SQNs, the validity of theories introducing mechanisms that increase their stability should continue to be tested. To stimulate electromagnetic SQN searches, particularly space searches, we estimate the net charge that would develop on an SQN in space exposed to various radiation baths (and showers) capable of liberating their less strongly bound electrons, taking into account recombination with ambient electrons. We consider, in particular, the cosmic background radiation, radiation from the sun, and diffuse galactic and extragalactic $γ$-ray backgrounds. A possible dramatic signal of SQNs in explosive astrophysical events is noted.

astro-ph↗

arXiv2001

Neutrino Scattering in a Magnetic Field

Motivated by the evidence for a finite neutrino mass we examine anew the interaction of neutrinos in a magnetic field. We present the rate for radiative scattering for both massless and massive neutrinos in the standard model and give the corresponding numerical estimates. We also consider the effects arising from a possible neutrino magnetic moment.

hep-ph↗

arXiv1999

Collider Tests of Compact Space Dimensions Using Weak Gauge Bosons

We present collider tests of the recent proposal for weak-scale quantum gravity due to new large compact space dimensions in which only the graviton ($\G$) propagates. We show that the existing high precision LEP-I $Z$-pole data can impose non-trivial constraints on the scale of the new dimensions, via the decay mode $Z\to f\bar{f}+\G$ ($f=q,\ell$). These bounds are comparable to those obtained at high energy colliders and provide the first sensitive probe of the scalar graviton. We also study $W(Z)+\G$ production and the anomalous $WW(ZZ)$ signal from virtual $\G$-states at the Fermilab Tevatron, and compare them with the LEP-I bound and those from LEP-II and future linear colliders.

hep-ph↗

arXiv1998

Higgs-photon associated production at hadron colliders

We present cross sections for the reactions p pbar --> H gamma and pp --> Hγarising from the subprocess q qbar --> H gamma. The calculation includes the complete one-loop contribution from all light quarks as well as the tree contributions from light quarks and c and b quarks. These are the main sources of Higgs-photon associated production at hadron colliders. At Tevatron energies, the cross section is typically between 0.1fb and 1 fb for 80 Gev < m_H < 160 GeV, and at LHC energies it exceeds about 2 fb over the same range of m_H. While substantial, these cross sections are not large enough to produce a signal which is discernable above the backgrounds from q qbar-->b bbar gamma and gg-->b bbar gamma.

hep-ph↗

arXiv1997

Higgs-photon production at μ\barμ colliders

We present cross sections for the reaction $μ\barμ\to Hγ$ over a range of $μ\barμ$ collider energies. The amplitudes for this process receive tree level contributions and one-loop contributions, which are of comparable magnitude. The tree level amplitudes are dominated by helicity non-flip terms and the one-loop amplitudes are dominated by helicity flip terms. As a consequence, the interference terms between the tree level and one-loop contributions are negligible. For a 500 GeV $μ\barμ$ collider, the cross section for $Hγ$ associated production approaches 0.1 fb.

hep-ph↗