15 research outputs found

### Probing the Randall-Sundrum geometric origin of flavor with lepton flavor violation

The ``anarchic'' Randall-Sundrum model of flavor is a low energy solution to
both the electroweak hierarchy and flavor problems. Such models have a warped,
compact extra dimension with the standard model fermions and gauge bosons
living in the bulk, and the Higgs living on or near the TeV brane. In this
paper we consider bounds on these models set by lepton flavor violation
constraints. We find that loop-induced decays of the form l->l'+gamma are
ultraviolet sensitive and uncalculable when the Higgs field is localized on a
four-dimensional brane; this drawback does not occur when the Higgs field
propagates in the full five-dimensional space-time. We find constraints at the
few TeV level throughout the natural range of parameters, arising from
muon-electron conversion in the presence of nuclei, rare muon decays, and rare
tau decays. A "tension" exists between loop-induced dipole decays such as
mu->e+gamma and tree-level processes such as muon-electron conversion; they
have opposite dependences on the five-dimensional Yukawa couplings, making it
difficult to decouple flavor-violating effects. We emphasize the importance of
the future experiments MEG and PRIME. These experiments will definitively test
the Randall-Sundrum geometric origin of hierarchies in the lepton sector at the
TeV-scale.Comment: 27 pgs, 15 figs; v2: numerical bug in tau decays fixe

### R-symmetric Gauge Mediation and the MRSSM

This is an invited summary of a seminar talk given at various institutions in
the United States and Canada. After a brief introduction, a review of the
minimal R-symmetric supersymmetric standard model is given, and the benefits to
the flavor sector are discussed. R-symmetric gauge mediation is an attempt to
realize this model using metastable supersymmetry breaking techniques. Sample
low energy spectra are presented and tuning is discussed. Various other
phenomenological results are summarized.Comment: 14 pages, invited Brief Review, submitted to Modern Physics Letters
A; v2: replaced Figure 1, updated acknowledgments, fixed typo

### QCD Corrections to K-Kbar Mixing in R-symmetric Supersymmetric Models

The leading-log QCD corrections to K-Kbar mixing in R-symmetric
supersymmetric models are computed using effective field theory techniques. The
spectrum topology where the gluino is significantly heavier than the squarks is
motivated and focused on. It is found that, like in the MSSM, QCD corrections
can tighten the kaon mass difference bound by roughly a factor of three. CP
violation is also briefly considered, where QCD corrections can constrain
phases to be as much as a factor of ten smaller than the uncorrected value.Comment: 11 pages, 11 pdf-figures; updated acknowledgments and references,
clarified relationship to Ref[17], clarified CP-violation sectio

### R-symmetric gauge mediation

We present a version of Gauge Mediated Supersymmetry Breaking which preserves
an R-symmetry - the gauginos are Dirac particles, the A-terms are zero, and
there are four Higgs doublets. This offers an alternative way for gauginos to
acquire mass in the supersymmetry-breaking models of Intriligator, Seiberg, and
Shih. We investigate the possibility of using R-symmetric gauge mediation to
realize the spectrum and large sfermion mixing of the model of Kribs, Poppitz,
and Weiner.Comment: 26+ pages, 3 figures, BIBTEX; v2 published version: references added,
paragraph on spectrum running removed, section added on adjoint scalar
masses, clarification of the meaning of Table 3 adde

### The flavor puzzle in multi-Higgs models

We reconsider the flavor problem in the models with two Higgs doublets. By
studying two generation toy models, we look for flavor basis independent
constraints on Yukawa couplings that will give us the mass hierarchy while
keeping all Yukawa couplings of the same order. We then generalize our findings
to the full three generation Standard Model. We find that we need two
constraints on the Yukawa couplings to generate the observed mass hierarchy,
and a slight tuning of Yukawa couplings of order 10%, much less than the
Standard Model. We briefly study how these constraints can be realized, and
show how flavor changing currents are under control for $K-\bar{K}$ mixing in
the near-decoupling limit.Comment: 26 pages, typos are corrected, references are added, the final
versio

### Threshold effects in excited charmed baryon decays

Motivated by recent results on charmed baryons from CLEO and FOCUS, we
reexamine the couplings of the orbitally excited charmed baryons. Due to its
proximity to the [Sigma_c pi] threshold, the strong decays of the
Lambda_c(2593) are sensitive to finite width effects. This distorts the shape
of the invariant mass spectrum in Lambda_{c1}-> Lambda_c pi^+pi^- from a simple
Breit-Wigner resonance, which has implications for the experimental extraction
of the Lambda_c(2593) mass and couplings. We perform a fit to unpublished CLEO
data which gives M(Lambda_c(2593)) - M(Lambda_c) = 305.6 +- 0.3 MeV and h2^2 =
0.24^{+0.23}_{-0.11}, with h2 the Lambda_{c1}-> Sigma_c pi strong coupling in
the chiral Lagrangian. We also comment on the new orbitally excited states
recently observed by CLEO.Comment: 9 pages, 3 figure

### Effective field theories

This book is a broad-based text intended to help the growing student body interested in topics such as gravitational effective theories, supersymmetric effective theories, applications of effective theory techniques to problems in condensed matter physics (superconductivity) and quantum chromodynamics (such as soft-collinear effective theory). It begins with a review of the use of symmetries to identify the relevant degrees of freedom in a problem, and then presents a variety of methods that can be used to solve physical problems. A detailed discussion of canonical examples of effective field theories with increasing complexity is then conducted. Special cases such as supersymmetry and lattice EFT are discussed, as well as recently-found applications to problems in gravitation and cosmology. An appendix includes various factoids from group theory and other topics that are used throughout the text, in an attempt to make the book self-contained