Hyperfine splitting in muonic hydrogen constrains new pseudoscalar interactions

We constrain the possibility of a new pseudoscalar coupling between the muon and proton using a recent measurement of the 2S hyperfine splitting in muonic hydrogen.Comment: 3 pages, 2 figures. Version to appear in PL

The Decay Rate Asymmetry of the Top Quark

The asymmetries {\cal A}_k \equiv [\Gamma(\twddec) -\Gamma(\tbwddec)] /[\Gamma(\twddec) + \Gamma(\tbwddec)] in the partial widths of the top quark decays are discussed within the Standard Model (SM), the Two-Higgs-Doublet Model (2HDM) and supersymmetric extensions of the SM (SSM). The leading contributions to these asymmetries in the SM and in the 2HDM are induced by the up-type quark self-energy diagrams and are found to be very small. However, in the SSM, the asymmetry ${\cal A}_b$ can be substantial, ${\cal O}(\alpha_{QCD})$, provided the CP-violating phase of gluino-top-stop couplings is not suppressed. Within the SSM ${\cal A}_b$ is generated by the vertex corrections.Comment: 9 pages, 3 figures (not included, postscript files available when requested). CERN-TH.6941/93,UICHEP-TH/93-1

Generic dark matter signature for gamma-ray telescopes

We describe a characteristic signature of dark matter (DM) annihilation or decay into gamma-rays. We show that if the total angular momentum of the initial DM particle(s) vanishes, and helicity suppression operates to prevent annihilation/decay into light fermion pairs, then the amplitude for the dominant 3-body final state f^+f^-\gamma has a unique form dictated by gauge invariance. This amplitude and the corresponding energy spectra hold for annihilation of DM Majorana fermions or self-conjugate scalars, and for decay of DM scalars, thus encompassing a variety of possibilities. Within this scenario, we analyze Fermi LAT, PAMELA and HESS data, and predict a hint in future Fermi gamma-ray data that portends a striking signal at atmospheric Cherenkov telescopes (ACTs).Comment: 9 pages, 4 figures. Version to appear in PR

Physics at e-e- Colliders

An overview of the physics motivations for e-e- colliders is presented.Comment: 10 pages. Opening lecture of the 3nd International Workshop on Electron-Electron Interactions at TeV Energies (e-e-99), University of California, Santa Cruz, 10-12 December 199