Charged Current Universality and the MSSM

We analyze the prospective impact of supersymmetric radiative corrections on tests of charged current universality involving light quarks and leptons. Working within the R-parity conserving Minimal Supersymmetric Standard Model, we compute the corresponding one-loop corrections that enter the extraction of the Cabibbo-Kobayashi-Maskawa matrix element $V_{ud}$ from a comparison of the muon-decay Fermi constant with the vector coupling constant determined from nuclear and neutron $\beta$-decay. We also revisit earlier studies of the corrections to the ratio $R_{e/\mu}$ of pion leptonic decay rates $\Gamma[\pi^+ \to e^+ \nu (\gamma)]$ and $\Gamma[\pi^+ \to \mu^+ \nu (\gamma)]$. In both cases, we observe that the magnitude of the corrections can be on the order of $10^{-3}$. We show that a comparison of the first row CKM unitarity tests with measurements of $R_{e/\mu}$ can provide unique probes of the spectrum of first generation squarks and first and second generation sleptons.Comment: 38 pages, 17 figure

Meson Scattering in a Pion Superfluid

Instead of the fermion-fermion scattering which identifies the BCS-BEC crossover in cold atom systems, boson-boson scattering is measurable and characterizes the BCS-BEC crossover at quark level. We study $\pi$-$\pi$ scattering in a pion superfluid described by the Nambu--Jona-Lasinio model. We found that the scattering amplitude drops down monotonically with decreasing isospin density and finally vanishes at the boundary of the phase transition. This indicates a BCS-BEC crossover in the pion superfluid.Comment: 5 pages, 3 figure

Measurements of the (n,p) Reaction at IUCF

This research was sponsored by the National Science Foundation Grant NSF PHY 87-1440

Study of (n,p) Reactions Between 100 and 200 MeV

This research was sponsored by the National Science Foundation Grant NSF PHY 87-1440