Yukawa Unification: The Good, The Bad and The Ugly

We analyze some consequences of grand unification of the third-generation Yukawa couplings, in the context of the minimal supersymmetric standard model. We address two issues: the prediction of the top quark mass, and the generation of the top-bottom mass hierarchy through a hierarchy of Higgs vacuum expectation values. The top mass is strongly dependent on a certain ratio of superpartner masses. And the VEV hierarchy always entails some tuning of the GUT-scale parameters. We study the RG equations and their semi-analytic solutions, which exhibit several interesting features, such as a focusing effect in the limit of certain symmetries and a correlation between the $A$ terms (which contribute to $b\rightarrow s\gamma$) and the gaugino masses. This study shows that non-universal soft-SUSY-breaking masses are favored (in particular for splitting the Higgs doublets via D-terms and for allowing more natural scenarios of symmetry breaking), and hints at features desired in Yukawa-unified models. Several phenomenological implications are also revealed.Comment: (talk Uri Sarid at the Second IFT Workshop on Yukawa Couplings and the Origins of Mass, 11-13 February 1994, Gainesville, Florida), 18 pages plus 3 uuencoded figures (included at bottom), REVISED: small typos have been fixed and some clarifications and a few forgotten acknowledgments and references have been added. straight LATeX, SU-ITP-94/1

Mesino - Antimesino Oscillations

The phenomenological implications of supersymmetric theories with low scale supersymmetry breaking and a squark as the lightest standard model superpartner are investigated. Such squarks hadronize with light quarks, forming sbaryons and mesinos before decaying. Production of these supersymmetric bound states at a high energy collider can lead to displaced jets with large negative impact parameter. Neutral mesino - antimesino oscillations are not forbidden by any symmetry and can occur at observable rates with distinctive signatures. Stop mesino - antimesino oscillations would give a sensitive probe of up-type sflavor violation in the squark sector, and can provide a discovery channel for supersymmetry through events with a same-sign top-top topology.Comment: 4 pages, 1 figure, LaTe

Gravitational Smearing of Minimal Supersymmetric Unification Predictions

A short and mean paper.Comment: 10 pages total + 1 postscript figure (included), revised: all lines are TRULY < 70 characters long (try it!); LBL-32905, UCB-PTH-92/3

Testing the Standard Model and Schemes for Quark Mass Matrices with CP Asymmetries in B Decays

The values of $\sin (2 \alpha)$ and $\sin (2 \beta)$, where $\alpha$ and $\beta$ are angles of the unitarity triangle, will be readily measured in a B factory (and maybe also in hadron colliders). We study the standard model constraints in the $\sin (2 \alpha) - \sin (2 \beta)$ plane. We use the results from recent analyses of $f_B$ and $\tau_b|V_{cb}|^2$ which take into account heavy quark symmetry considerations. We find $\sin (2 \beta) \geq 0.15$ and most likely \sin (2 \beta) \roughly{>} 0.6, and emphasize the strong correlations between $\sin (2 \alpha)$ and $\sin (2 \beta)$. Various schemes for quark mass matrices allow much smaller areas in the $\sin (2 \alpha) - \sin (2 \beta)$ plane. We study the schemes of Fritzsch, of Dimopoulos, Hall and Raby, and of Giudice, as well as the ``symmetric CKM'' idea, and show how CP asymmetries in B decays will crucially test each of these schemes.Comment: 11 pages and 4 postscript figures available on request, LaTeX, WIS-92/52/Jun-PH, LBL-3256

Tools for Tunneling

If the universe is trapped and cooled in a metastable false vacuum state, that state will eventually decay by bubble nucleation and expansion. For example, many extensions of the standard model incorporate new scalar fields whose potential has a local minimum at the origin but a global minimum elsewhere, to which the vacuum will eventually tunnel. I calculate the lifetime of the false vacuum, and the field profile of the bubble after tunneling, for any potential that is approximately a polynomial of degree <= 4 near the false vacuum. Essentially exact results are given for a single field; for multiple fields the given action is a strict upper bound.Comment: RevTeX, 4 pages, including 3 eps figures embedded via epsfig; revised version (minor typos corrected, reference added, clarifications made) to appear in Phys. Rev.

Low-Energy Signals for a Minimal Gauge-Mediated Model

The inclusive branching ratio $B \to X_s\gamma$ and the anomalous magnetic moment $g_\mu-2$ of the muon are accurately calculated within a minimal gauge-mediated SUSY-breaking model which naturally generates a large $\tan\beta$. The predictions are in somewhat better agreement with current experiments, and new data will soon critically test these predictions. Predictions for $B \to X_s\ell^+\ell^-$ branching ratios and asymmetries, to be tested at future colliders, are also presented.Comment: LaTeX, 9 pages, including 1 (color) figure embedded using epsf macros; minor change to text and figure, added 1 referenc