Yael Shadmi

Dynamical Supersymmetry Breaking

Supersymmetry is one of the most plausible and theoretically motivated frameworks for extending the standard model. However, any supersymmetry in Nature must be a broken symmetry. Dynamical supersymmetry breaking (DSB) is an attractive idea for incorporating supersymmetry into a successful description of Nature. The study of DSB has recently enjoyed dramatic progress, fueled by advances in our understanding of the dynamics of supersymmetric field theories. These advances have allowed for direct analysis of DSB in strongly coupled theories, and for the discovery of new DSB theories, some of which contradict early criteria for DSB. The authors review these criteria, emphasizing recently discovered exceptions. They also describe, through many examples, various techniques for directly establishing DSB by studying the infrared theory, including both older techniques in regions of weak coupling and new techniques in regions of strong coupling. Finally, they present a list of representative DSB models, their main properties, and the relations among them. (c) 2000 The American Physical Society.

Deconstruction and gauge theories in AdS5

On a slice of AdS5, despite having a dimensionful coupling, gauge theories can exhibit logarithmic dependence on scale. In this paper, we utilize deconstruction to analyze the scaling behavior of the theory, both above and below the AdS curvature scale, and shed light on position-dependent regularizations of the theory. We comment on applications to geometries other than AdS.

Neutrino parameters, Abelian flavor symmetries, and charged lepton flavor violation

Neutrino masses and mixings have important implications for models of fermion masses, and, most directly, for the charged lepton sector. We consider supersymmetric Abelian flavor models, where neutrino mass parameters are related to those of charged leptons and sleptons. We show that processes such as {tau}{yields}{mu}{gamma}, {mu}{yields}e{gamma} and {mu}-e conversion provide interesting probes. In particular, some existing models are excluded by current bounds, while many others predict rates within reach of proposed near future experiments. We also construct models in which the predicted rates for charged lepton flavor violation are below even the proposed experimental sensitivities, but argue that such models necessarily involve loss of predictive power. (c) 2000 The American Physical Society.

Flavored Gauge Mediation, A Heavy Higgs, and Supersymmetric Alignment

A bstractWe show that the messenger-matter couplings of Flavored Gauge Mediation Models can generate substantial stop mixing and new contributions to the stop masses, leading to Higgs masses around 126 GeV with sub-TeV superpartners, and with some colored superpartners around 1-2 TeV in parts of the parameter space. We study the spectra of a few examples with a single messenger pair coupling dominantly to the top, for different messenger scales. Flavor constraints in these models are obeyed by virtue of supersymmetric alignment: the same flavor symmetry that explains fermion masses dictates the structure of the matter-messenger couplings, and this structure is inherited by the soft terms. We present the leading 1-loop and 2-loop contributions to the soft terms for general coupling matrices in generation space. Because of the Higgs-messenger mixing induced by the new couplings, the calculation of these soft terms via analytic continuation requires careful matching of the high- and low-energy theories. We discuss the calculation in detail in the appendix.

Flavored gauge-mediation

The messengers of Gauge-Mediation Models can couple to standard-model matter fields through renormalizable superpotential couplings. These matter-messenger couplings generate generation-dependent sfermion masses and are therefore usually forbidden by discrete symmetries. However, the non-trivial structure of the standard-model Yukawa couplings hints at some underlying flavor theory, which would necessarily control the sizes of the matter-messenger couplings as well. Thus for example, if the doublet messenger and the Higgs have the same properties under the flavor theory, the resulting messenger-lepton couplings are parametrically of the same order as the lepton Yukawas, so that slepton mass-splittings are similar to those of minimally-flavor-violating models and therefore satisfy bounds on flavor-violation, with, however, slepton mixings that are potentially large. Assuming that fermion masses are explained by a flavor symmetry, we construct viable and natural models with messenger-lepton couplings controlled by the flavor symmetry. The resulting slepton spectra are unusual and interesting, with slepton mass-splittings and mixings that may be probed at the LHC. In particular, since the new contributions are typically negative, and since they are often larger for the first- and second-generation sleptons, some of these examples have the selectron or the smuon as the lightest slepton, with mass splittings of a few to tens of GeV.

Standard model and supersymmetric flavor puzzles at the CERN Large Hadron Collider

Can the Large Hadron Collider explain the masses and mixings of the known fermions? A promising possibility is that these masses and mixings are determined by flavor symmetries that also govern new particles that will appear at the LHC. We consider well-motivated examples in supersymmetry with both gravity and gauge mediation. Contrary to spreading belief, new physics need not be minimally flavor violating. We build nonminimally flavor violating models that successfully explain all known lepton masses and mixings, but span a wide range in their predictions for slepton flavor violation. In natural and favorable cases, these models have metastable sleptons and are characterized by fully reconstructible events. We outline many flavor measurements that are then possible and describe their prospects for resolving both the standard model and new physics flavor puzzles at the Large Hadron Collider.

Theoretical expectations for the muon's electric dipole moment

Abstract We examine the muons electric dipole moment dμ from a variety of theoretical perspectives. We point out that the reported deviation in the muons g−2 can be due partially or even entirely to a new physics contribution to the muons electric dipole moment. In fact, the recent g−2 measurement provides the most stringent bound on dμ to date. This ambiguity could be definitively resolved by the dedicated search for dμ recently proposed. We then consider both model-independent and supersymmetric frameworks. Under the assumptions of scalar degeneracy, proportionality, and flavor conservation, the theoretical expectations for dμ in supersymmetry fall just below the proposed sensitivity. However, nondegeneracy can give an order of magnitude enhancement, and lepton flavor violation can lead to d μ ∼10 −22 e cm , two orders of magnitude above the sensitivity of the dμ experiment. We present compact expressions for leptonic dipole moments and lepton flavor violating amplitudes. We also derive new limits on the amount of flavor violation allowed and demonstrate that approximations previously used to obtain such limits are highly inaccurate in much of parameter space.

Exact results in 5D from instantons and deconstruction

We consider non-perturbative effects in theories with extra dimensions and the deconstructed versions of these theories. We establish the rules for instanton calculations in 5D theories on the circle, and use them for an explicit one-instanton calculation in a supersymmetric gauge theory. The results are then compared to the known exact Seiberg-Witten type solution for this theory, confirming the validity both of the exact results and of the rules for instanton calculus for extra dimensions introduced here. Next we consider the non-perturbative results from the perspective of deconstructed extra dimensions. We show that the non-perturbative results of the deconstructed theory do indeed reproduce the known results for the continuum extra dimensional theory, thus providing the first non-perturbative evidence in favor of deconstruction. This way deconstruction also allows us to make exact predictions in higher dimensional theories which agree with earlier results, and helps to clarify the interpretation of 5D instantons.

Non-Degenerate Squarks from Flavored Gauge Mediation

A bstractWe study the squark spectra of Flavored Gauge Mediation Models, in which messenger-matter uperpotential couplings generate new, generation-dependent contributions to the squark masses. The new couplings are controlled by the same flavor symmetry that explains the fermion masses, leading to excellent alignment of the quark and squark mass matrices. This allows for large squark mass splittings consistent with all flavor bounds. In particular, second-generation squarks are often significantly lighter than the first-generation squarks. As squark production at the LHC is dominated by the up- and down-squarks and the efficiencies for squark searches increase with their masses, the charm and/or strange squark masses can be well below the current LHC bounds. At the same time, even with a single set of messengers, the models can generate large stop mixings which result in large loop contributions to the Higgs mass.

Visible effects of the hidden sector

The renormalization of operators responsible for soft supersymmetry breaking is usually calculated by starting at some high scale and including only visible sector interactions in the evolution equations, while ignoring hidden sector interactions. Here we explain why this is correct only for the most trivial structures in the hidden sector and discuss possible implications. This investigation was prompted by the idea of conformal sequestering. In that framework hidden sector renormalizations by nearly conformal dynamics are critical. In the original models of conformal sequestering it was necessary to impose hidden sector flavor symmetries to achieve the sequestered form. We present models that can evade this requirement and lead to no-scale or anomaly mediated boundary conditions, but the necessary structures do not seem generic. More generally, the ratios of scalar masses to gaugino masses, the m term, the Bm term, A terms, and the gravitino mass can be significantly affected.