634 research outputs found
Plaque-Like Sclerodermiform Localized Mucinosis Rapidly Responsive to Topical Tacrolimus
We report the successful treatment of plaque-like sclerodermiform mucinosis using tacrolimus ointment topically. We present a 70-year-old male with a large chronic erythema and hardening of the nuchal skin and shoulder area. Subjective symptoms were a moderate pruritus and a rather disabling stiffness. A biopsy specimen revealed typical features of lichen myxedematosus. In a subsequent clinical examination, no associated illnesses such as hypothyroidism or gammopathy were found. Since no established therapy exists for this condition, and as there was a lack of response to potent topical glucocorticosteroids, tacrolimus 0.03% ointment was used off-label twice daily. Surprisingly, this resulted in a rapid, almost complete clearance of the skin within three weeks of treatment
The Little Hierarchy in Universal Extra Dimensions
In the standard model in universal extra dimensions (UED) the mass of the
Higgs field is driven to the cutoff of the higher-dimensional theory. This
re-introduces a small hierarchy since the compactification scale 1/R should not
be smaller than the weak scale. In this paper we study possible solutions to
this problem by considering five-dimensional theories where the Higgs field
potential vanishes at tree level due to a global symmetry. We consider two
avenues: a Little Higgs model and a Twin Higgs model. An obstacle for the
embedding of these four-dimensional models in five dimensions is that their
logarithmic sensitivity to the cutoff will result in linear divergences in the
higher dimensional theory. We show that, despite the increased cutoff
sensitivity of higher dimensional theories, it is possible to control the Higgs
mass in these two scenarios. For the Little Higgs model studied, the
phenomenology will be significantly different from the case of the standard
model in UED. This is due to the fact that the compactification scale
approximately coincides with the scale where the masses of the new states
appear. For the case of the Twin Higgs model, the compactification scale may be
considerably lower than the scale where the new states appear. If it is as low
as allowed by current limits, it would be possible to experimentally observe
the standard model Kaluza-Klein states as well as a new heavy quark. On the
other hand, if the compactification scale is higher, then the phenomenology at
colliders would coincide with the one for the standard model in UED.Comment: 25 pages, 2 figure
Understanding Pound-Drever-Hall locking using voltage controlled radio-frequency oscillators: An undergraduate experiment
We have developed a senior undergraduate experiment that illustrates
frequency stabilization techniques using radio-frequency electronics. The
primary objective is to frequency stabilize a voltage controlled oscillator to
a cavity resonance at 800 MHz using the Pound-Drever-Hall method. This
technique is commonly applied to stabilize lasers at optical frequencies. By
using only radio-frequency equipment it is possible to systematically study
aspects of the technique more thoroughly, inexpensively, and free from eye
hazards. Students also learn about modular radio-frequency electronics and
basic feedback control loops. By varying the temperature of the resonator,
students can determine the thermal expansion coefficients of copper, aluminum,
and super invar.Comment: 9 pages, 10 figure
Little Higgs model effects in
Though the predictions of the Standard Model (SM) are in excellent agreement
with experiments there are still several theoretical problems associated with
the Higgs sector of the SM, where it is widely believed that some ``{\it new
physics}'' will take over at the TeV scale. One beyond the SM theory which
resolves these problems is the Little Higgs (LH) model. In this work we have
investigated the effects of the LH model on \gggg scattering
\cite{Choudhury:2006xa}.Comment: Talk given at LCWS06, Bangalore, 4 pages (style files included
Report of the Subgroup on Alternative Models and New Ideas
We summarize some of the work done by the P3 subgroup on Alternative Models
and New Ideas. The working group covered a broad range of topics including a
constrained Standard Model from an extra dimension, a discussion of recent
ideas addressing the strong CP problem, searches for doubly charged higgs
bosons in e gamma collisions, and an update on discovery limits for extra
neutral gauge bosons at hadron colliders. The breadth of topics reflects the
many ideas and approaches to physics beyond the Standard Model.Comment: 10 pages, 5 figures. Contributed to the APS/DPF/DPB Summer Study on
the Future of Particle Physics (Snowmass 2001), Snowmass, Colorado, 30 Jun -
21 Jul 200
Large N reduction with overlap fermions
We revisit quenched reduction with fermions and explain how some old problems
can be avoided using the overlap Dirac operator.Comment: Lattice2002(chiral) 3 pages, no figure
The Phase Structure of Supersymmetric Sp(2N_c) Gauge Theories with an Adjoint
We study the phase structure of N = 1 supersymmetric Sp(2N_c) gauge theories
with 2N_f fundamentals, an adjoint, and vanishing superpotential. Using
a-maximization, we derive analytic expressions for the values of N_f below
which the first several gauge-invariant operators in the chiral ring violate
the unitarity bound and become free fields. In doing so we are able to
explicitly check previous conjectures about the behavior of this theory made by
Luty, Schmaltz, and Terning. We then compare this to an analysis of the first
two 'deconfined' dual descriptions based on the gauge groups Sp(2N_f+2) x
SO(2N_c+5) and Sp(2N_f+2) x SO(4N_f+4) x Sp(2N_c+2), finding precise agreement.
In particular, we find no evidence for non-obvious accidental symmetries or the
appearance of a mixed phase in which one of the dual gauge groups becomes free.Comment: 18 pages, 2 figures; v2: added references to match JHEP versio
Classical skyrmions in SU(N)/SO(N) cosets
We construct the skyrmion solutions appearing in the coset spaces SU(N)/SO(N)
for N > 2 and compute their classical mass. For N = 3, the third homotopy group
pi_3(SU(3)/SO(3)) = Z_4 implies the existence of two distinct solutions: the
skyrmion of winding number two has spherical symmetry and is found to be the
lightest non-trivial field configuration; the skyrmion and antiskyrmion of
winding number plus and minus one are slightly heavier and of toroidal shape.
For N >= 4, there is only one skyrmion since the third homotopy group is Z_2.
It is found to have spherical symmetry and is significantly lighter than the N
= 3 solutions.Comment: 14 pages, 3 figures; v2: discussion improve
Higher dimensional supersymmetry in 4D superspace
We present an explicit formulation of supersymmetric Yang-Mills theories from
\D= 5 to 10 dimensions in the familiar \N=1,\D=4 superspace. This provides
the rules for globally supersymmetric model building with extra dimensions and
in particular allows us to simply write down SUSY preserving
interactions between bulk fields and fields localized on branes. We present a
few applications of the formalism by way of illustration, including
supersymmetric ``shining'' of bulk fields, orbifolds and localization of chiral
fermions, anomaly inflow and super-Chern-Simons theories.Comment: Typos corrected. Added reference to early work by Marcus, Sagnotti
and Siegel and a term to the non-Abelian Lagrangian for D>5 formally needed
for gauge invariance. The results however remain unchange
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