Nuclei as Laboratories: Nuclear Tests of Fundamental Symmetries

The prospect of a rare isosotope accelerator facility opens up possibilities for a new generation of nuclear tests of fundamental symmetries. In this talk, I survey the current landscape of such tests and discuss future opportunities that a new facility might present.Comment: To appear in proceedings of 3rd ANL/MSU/INT/JINA Theory Workshop, Argonne National Laboratory (April, 2006); 13 page

Searching for T-Violating, P-Conserving New Physics with Neutrons

The observance of parity conserving time reversal violation in light quark systems could signal the presence of physics beyond the Standard Model. I discuss the implications of low-energy time reversal tests for the existence of such T-violating, P-conserving (TVPC) interactions. I argue that searches for permanent electric dipole moments (EDM's) and direct TVPC searches provide complementary information on P-conserving T-violation. EDM searches yield constraints only under the assumption that parity symmetry is restored at the scale Lambda associated with new TVPC physics. If parity remains broken at short distances, direct searches yield the least ambiguous bounds. In the latter case, improving the experimental precision of direct TVPC searches in neutron beta-decay and polarized epithermal neutron transmission at the Spallation Neutron Source could yield tighter bounds.Comment: To appear in proceedings of Workshop on Fundamental Physics with Pulsed Neutron Beams, held at the Research Triangle Park, North Carolina, June 1 -- 3, 2000. Nine page

Electrons, New Physics, and the Future of Parity-Violation

The study of parity-violation in semi-leptonic processes has yielded important insights into the structure of the Standard Model and the substructure of the nucleon. I discuss the future of semi-leptonic parity-violation and the role it might play in uncovering physics beyond the Standard Model.Comment: To apperar in the Proceedings of the Bates25 Symposium. 18pgs. Uses aipproc.sty (included

Chiral Symmetries and Low Energy Searches for New Physics

I discuss low energy searches for new physics beyond the Standard Model, identifying the role played by chiral symmetries in these searches and in various new physics scenarios. I focus in particular on electric dipole moment searches; precision studies of weak decays and electron scattering; and neutrino properties and interactions.Comment: Talk given at 5th International Workshop on Chiral Dynamics, Durham/Chapel Hill, NC (September, 2006); 12 page

Electron-to-Tau Lepton Flavor Violation at the Electron-Ion Collider

We analyze the potential sensitivity of a search for $e\rightarrow\tau$ conversion at a proposed electron-ion collider (EIC) facility. To that end, we calculate the cross sections for $e\rightarrow\tau$ events in a leptoquark framework assuming that the leptoquark masses are on the order of several hundred GeV or more. Given present limits on leptoquarks from direct searches at HERA and rare decay processes, an EIC sensitive to 0.1 fb $e\rightarrow\tau$ cross sections could probe previously unexplored regions of parameter space for these lepton flavor violating events (assuming 90 GeV center-of-mass energy and 10 fb$^{-1}$ integrated luminosity). Depending on the species of leptoquark and flavor structure of the couplings, an EIC search could surpass the HERA and rare process sensitivity to $e\rightarrow\tau$ conversion amplitudes by as much as an order of magnitude or more. We also derive updated limits on quark flavor-diagonal LFV leptoquark interactions using the most recent BaBar $\tau\rightarrow e\gamma$ search. We find that limits from an EIC $e\rightarrow\tau$ search could be competitive with the most recent $\tau\rightarrow e\gamma$ limit for a subset of the quark flavor-diagonal leptoquark couplings. Using an SU(5) GUT model in which leptoquark couplings are constrained by the neutrino masses and mixing, we illustrate how observable leptoquark-induced $e\rightarrow\tau$ conversion can be consistent with stringent LFV limits imposed by $\mu\rightarrow e\gamma$ and $\mu\rightarrow e$ conversion searches.Comment: 19 pages, 7 figure

Electroweak Baryogenesis, Electric Dipole Moments, and Higgs Diphoton Decays

We study the viability of electroweak baryogenesis in a two Higgs doublet model scenario augmented by vector-like, electroweakly interacting fermions. Considering a limited, but illustrative region of the model parameter space, we obtain the observed cosmic baryon asymmetry while satisfying present constraints from the non-observation of the permanent electric dipole moment (EDM) of the electron and the combined ATLAS and CMS result for the Higgs boson diphoton decay rate. The observation of a non-zero electron EDM in a next generation experiment and/or the observation of an excess (over the Standard Model) of Higgs to diphoton events with the 14 TeV LHC run or a future $e^+e^-$ collider would be consistent with generation of the observed baryon asymmetry in this scenario.Comment: 22 pages, 3 figure

Cuts, Cancellations and the Closed Time Path: The Soft Leptogenesis Example

By including all leading quantum-statistical effects at finite temperature, we show that no net asymmetry of leptons and sleptons is generated from soft leptogenesis, save the possible contribution from the resonant mixing of sneutrinos. This result contrasts with different conclusions appearing in the literature that are based on an incomplete inclusion of quantum statistics. We discuss vertex and wave-function diagrams as well as all different possible kinematic cuts that nominally lead to CP-violating asymmetries. The present example of soft leptogenesis may therefore serve as a paradigm in order to identify more generally applicable caveats relevant to alternative scenarios for baryogenesis and leptogenesis, and it may provide useful guidance in constructing viable models.Comment: 38 page