What is the Natural Size of Supersymmetric CPCP Violation?

It is well known that if phases and masses in the Minimal Supersymmetric Standard Model (MSSM) are allowed to have general values, the resulting neutron EDM ($d_n$) exceeds the experimental upper limit by about $10^3$. We assume that the needed suppression is not due to a fine-tuning of phases or masses, and ask what natural size of $CP$ violation (CPV) results. We show that (1) the phase of one of the superpotential parameters, $\mu$, does not contribute to any CPV in the MSSM and so is not constrained by \dn; (2) the MSSM contribution to $d_n$ is tiny, just coming from the CKM phase; (3) the phases in the MSSM cannot be used to generate a baryon asymmetry at the weak scale, given our assumptions; and (4) in non-minimal SUSY models, an effective phase can enter at one loop giving $d_n \sim 10^{-26}$\ecm, $d_e \sim 10^{-27}$\ecm, and allowing a baryon asymmetry to be generated at the weak scale, without fine-tunings. Our results could be evaded by a SUSY breaking mechanism which produced phases for the SUSY breaking parameters that somehow were naturally of order $10^{-3}$.Comment: 13pp (no figs), REVTEX (LATEX), TRI-PP-93-

How to Select Observers

A number of problems in physics, mathematics, and philosophy involve observers in given situations which lead to debates about whether observer-specific information should affect the probability for some outcome or hypothesis. Our purpose is not to advocate for such observer selection effects, but rather to show that any such effects depend greatly on the assumptions made. We focus on the debate about the existence of a `Doomsday effect'---whether observer index information should cause one to favor possibilities with fewer observers, which has been argued to have implications for models of cosmology. Our central goal is to reconcile the apparent inconsistencies in the literature by introducing a formalism to lay bare assumptions made and address a key issue that has not been clearly articulated in such problems: whether the observer is selected by *picking from* or *being in* a set of worlds. In the former there generally are observer selection effects, and in the latter there generally are not. This leads us to differentiate what we call *inclusive* from *exclusive* selection, and how they relate to the concept of a multiverse. Then we relax the assumption that all observers are equally typical, and consider the problem of Boltzmann brains, showing that typicality can play a role in solving the problem. We then stress the need for scale-invariant questions, which causes us to analyze J. Richard Gott's approach to the problem. This all allows us to analyze the Doomsday and Universal Doomsday arguments. We find that there is no Doomsday effect, absent a set of assumptions we find somewhat unreasonable. Then we use our formalism to resolve a debate in the philosophy community called the `Sleeping Beauty Problem.' Finally, we conclude with a heuristic summary, free from equations, and point to possible future directions of this line of research.Comment: 33 pages, 2 figures, 1 Table. To be published in Phys. Rev. Research. New title, minor changes, & summary table in response to peer revie

What can the L3 γγll\gamma\gamma ll events be?

We consider the 4 $\gamma\gamma ll$ ($l=\mu,\ e$) events reported by the L3 collaboration, and go through the logical possibilities which could explain the events. If they are not coincidental bremsstrahlung events, we find that the physics which they could point to is extremely limited. One possibility would be to have a new 60 GeV scalar (or pseudoscalar) particle $X^0$ with an off-diagonal coupling to a $Z$ and $Z'$ which is non-perturbative ($\alpha > 1$), where the $Z'$ couplings to $\nu\bar\nu$ are suppressed. One could also construct a model involving $X^0$, and a second scalar $X'^0$ with a large $X'll$ coupling. We do not promote either of these models, but hope they would prove to be useful guidelines, should the L3 events turn out to be new physics.Comment: 7 pp (3 fig avail. on request), LATEX, TRI-PP-92-12

Moderate Supersymmetric CP Violation

It is well known that supersymmetry (SUSY) gives neutron and electron electric dipole moments ($d_n$ and $d_e$) which are too large by about $10^{3}$. If we assume a SUSY model cannot contain fine-tunings or large mass scales, then one must require that the SUSY breaking mechanism give real soft breaking parameters, in which case the minimal SUSY model has no $CP$ violation other than from the CKM matrix (besides possible strong $CP$ violating effects). We show that in non-minimal SUSY models, a moderate amount of $CP$ violation can be induced through one loop corrections to the scalar potential, giving an effective phase of order $10^{-3}$, and thus implying $d_n$ and $d_e$ can be near their current experimental bounds $naturally$. This moderate amount of SUSY $CP$ violation could also prove important for models of electroweak baryogenesis. We illustrate our results with a specific model.Comment: 19pp plain LATEX, 1 fig (by EMAIL request), TRI-PP-93-86. (Some clarifying comments about renormalizability added--version to appear in Phys. Rev. D

CP violating polarizations in semileptonic heavy meson decays

We study the $T$-violating lepton transverse polarization ($P^\perp_l$) in three body semileptonic heavy meson decays to pseudoscalar mesons and to vector mesons. We calculate these polarizations in the heavy quark effective limit, which simplifies the expressions considerably. After examining constraints from $CP$ conserving (including $b \rightarrow s \gamma$) and $CP$ violating processes, we find that in $B$ decays, $P^\perp$ of the muon in multi-Higgs doublet models can be of order $10\%$, while $P^\perp$ of the $\tau$ can even approach unity. In contrast, $P^\perp_\mu$ in $D$ decays is at most 1.5\%. We discuss possibilities for detection of $P^\perp_l$ at current and future $B$ factories. We also show that $P^\perp_l$ in decays to vector mesons, unlike in decays to pseudoscalars, can get contributions from left-right models. Unfortunately, $P^\perp_l$ in that case is proportional to $W_L$-$W_R$ mixing, and is thus small.Comment: 32pp plain LATEX, 3 figs (by EMAIL request), TRI-PP-94-1

Using CP violation to seine and cull: The muon transverse polarization in semileptonic decays and the supersymmetric electric dipole moment of the neutron.

We explore two complementary uses of CP violating observables. The transverse polarization of the muon in K\sb{\mu3} decays is a promising tool for detecting new physics, because it gets no contribution from the Standard Model. To show that the transverse polarization is in principle sensitive enough to be seen in the near future, we construct three models which give a polarization of order 10\sp{-3}, while satisfying all experimental constraints. The complementary approach is exhibited by the constraints which the neutron electric dipole moment (NEDM) places on supersymmetric theories. We find that certain parameters of the low energy supergravity Lagrangian must be real in order to satisfy the experimental bound on the NEDM without resorting to fine-tunings or large mass scales. We believe that such a requirement should be imposed on all supersymmetric theories that are taken seriously. We show that the claim that the Polonyi model of supergravity naturally accomplishes this is in general false. Finally, we estimate finite loop effects due to the CKM matrix on the NEDM, through the squark mass matrix, and find them to be small.Ph.D.PhysicsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/103214/1/9308316.pdfDescription of 9308316.pdf : Restricted to UM users only