231 research outputs found
Lepton Polarization and Forward-Backward Asymmetries in b -> s tau+ tau-
We study the spin polarizations of both tau leptons in the decay b -> s tau+
tau-. In addition to the polarization asymmetries involving a single tau, we
construct asymmetries for the case where both polarizations are simultaneously
measured. We also study forward-backward asymmetries with polarized tau's. We
find that a large number of asymmetries are predicted to be large, >~ 10%. This
permits the measurement of all Wilson coefficients and the b-quark mass, thus
allowing the standard model (SM) to be exhaustively tested. Furthermore, there
are many unique signals for the presence of new physics. For example,
asymmetries involving triple-product correlations are predicted to be tiny
within the SM, O(10^{-2}). Their observation would be a clear signal of new
physics.Comment: 21 pages, LaTeX, 4 figures (included). Paper somewhat reorganized,
references greatly expanded, conclusions unchange
Clustering transitions in vibro-fluidized magnetized granular materials
We study the effects of long range interactions on the phases observed in
cohesive granular materials. At high vibration amplitudes, a gas of magnetized
particles is observed with velocity distributions similar to non-magnetized
particles. Below a transition temperature compact clusters are observed to form
and coexist with single particles. The cluster growth rate is consistent with a
classical nucleation process. However, the temperature of the particles in the
clusters is significantly lower than the surrounding gas, indicating a
breakdown of equipartition. If the system is quenched to low temperatures, a
meta-stable network of connected chains self-assemble due to the anisotropic
nature of magnetic interactions between particles.Comment: 4 pages, 5 figure
Possible Supersymmetric Effects on Angular Distributions in Decays
We investigate the angular distributions of the rare B decay, , in general supersymmetric extensions of the standard
model. We consider the new physics contributions from the operators
in small invariant mass region of lepton pair. We show that the
azimuthal angle distribution of the decay can tell us the new physics effects
clearly from the behavior of the distribution, even if new physics does not
change the decay rate substantially from the standard model prediction
A Systematic Analysis of the Lepton Polarization Asymmetries in the Rare B Decay, B -> X_s\tau^+\tau^-
The most general model-independent analysis of the lepton polarization
asymmetries in the rare B decay, \Bstt, is presented. We present the
longitudinal, normal and transverse polarization asymmetries for the
and , and combinations of them, as functions of the Wilson coefficients
of twelve independent four-Fermi interactions, ten of them local and two
nonlocal. These procedures will tell us which type of operators contributes to
the process. And it will be very useful to pin down new physics systematically,
once we have the experimental data with high statistics and a deviation from
the Standard Model is found.Comment: 24 pages, 8 figures, LaTe
Correlated sampling in quantum Monte Carlo: a route to forces
In order to find the equilibrium geometries of molecules and solids and to
perform ab initio molecular dynamics, it is necessary to calculate the forces
on the nuclei. We present a correlated sampling method to efficiently calculate
numerical forces and potential energy surfaces in diffusion Monte Carlo. It
employs a novel coordinate transformation, earlier used in variational Monte
Carlo, to greatly reduce the statistical error. Results are presented for
first-row diatomic molecules.Comment: 5 pages, 2 postscript figure
On post-Lie algebras, Lie--Butcher series and moving frames
Pre-Lie (or Vinberg) algebras arise from flat and torsion-free connections on
differential manifolds. They have been studied extensively in recent years,
both from algebraic operadic points of view and through numerous applications
in numerical analysis, control theory, stochastic differential equations and
renormalization. Butcher series are formal power series founded on pre-Lie
algebras, used in numerical analysis to study geometric properties of flows on
euclidean spaces. Motivated by the analysis of flows on manifolds and
homogeneous spaces, we investigate algebras arising from flat connections with
constant torsion, leading to the definition of post-Lie algebras, a
generalization of pre-Lie algebras. Whereas pre-Lie algebras are intimately
associated with euclidean geometry, post-Lie algebras occur naturally in the
differential geometry of homogeneous spaces, and are also closely related to
Cartan's method of moving frames. Lie--Butcher series combine Butcher series
with Lie series and are used to analyze flows on manifolds. In this paper we
show that Lie--Butcher series are founded on post-Lie algebras. The functorial
relations between post-Lie algebras and their enveloping algebras, called
D-algebras, are explored. Furthermore, we develop new formulas for computations
in free post-Lie algebras and D-algebras, based on recursions in a magma, and
we show that Lie--Butcher series are related to invariants of curves described
by moving frames.Comment: added discussion of post-Lie algebroid
Explicit differential characterization of the Newtonian free particle system in m > 1 dependent variables
In 1883, as an early result, Sophus Lie established an explicit necessary and
sufficient condition for an analytic second order ordinary differential
equation y_xx = F(x,y,y_x) to be equivalent, through a point transformation
(x,y) --> (X(x,y), Y(x,y)), to the Newtonian free particle equation Y_XX = 0.
This result, preliminary to the deep group-theoretic classification of second
order analytic ordinary differential equations, was parachieved later in 1896
by Arthur Tresse, a French student of S. Lie. In the present paper, following
closely the original strategy of proof of S. Lie, which we firstly expose and
restitute in length, we generalize this explicit characterization to the case
of several second order ordinary differential equations. Let K=R or C, or more
generally any field of characteristic zero equipped with a valuation, so that
K-analytic functions make sense. Let x in K, let m > 1, let y := (y^1, ...,
y^m) in K^m and let y_xx^j = F^j(x,y,y_x^l), j = 1,...,m be a collection of m
analytic second order ordinary differential equations, in general nonlinear. We
provide an explicit necessary and sufficient condition in order that this
system is equivalent, under a point transformation (x, y^1, ..., y^m) -->
(X(x,y), Y^1(x,y),..., Y^m(x, y)), to the Newtonian free particle system Y_XX^1
= ... = Y_XX^m = 0. Strikingly, the (complicated) differential system that we
obtain is of first order in the case m > 1, whereas it is of second order in S.
Lie's original case m = 1.Comment: 76 pages, no figur
Lepton polarization correlations in
In this work we will study the polarizations of both leptons () in the
decay channel . In the case of the dileptonic inclusive
decay , where apart from the polarization asymmetries
of single lepton , one can also observe the polarization asymmetries of
both leptons simultaneously. If this sort of measurement is possible then we
can have, apart from decay rate, FB asymmetry and the six single lepton
polarization asymmetries (three each for and ), nine more
double polarization asymmetries. This will give us a very useful tool in more
strict testing of SM and the physics beyond. We discuss the double polarization
asymmetries of leptons in the decay mode within
the SM and the Minimal Supersymmetric extensions of it.Comment: 21 pages, 21 figures; version to match paper to appear in PR
Experimental Probes of Localized Gravity: On and Off the Wall
The phenomenology of the Randall-Sundrum model of localized gravity is
analyzed in detail for the two scenarios where the Standard Model (SM) gauge
and matter fields are either confined to a TeV scale 3-brane or may propagate
in a slice of five dimensional anti-deSitter space. In the latter instance, we
derive the interactions of the graviton, gauge, and fermion Kaluza-Klein (KK)
states. The resulting phenomenological signatures are shown to be highly
dependent on the value of the 5-dimensional fermion mass and differ
substantially from the case where the SM fields lie on the TeV-brane. In both
scenarios, we examine the collider signatures for direct production of the
graviton and gauge KK towers as well as their induced contributions to
precision electroweak observables. These direct and indirect signatures are
found to play a complementary role in the exploration of the model parameter
space. In the case where the SM field content resides on the TeV-brane, we show
that the LHC can probe the full parameter space and hence will either discover
or exclude this model if the scale of electroweak physics on the 3-brane is
less than 10 TeV. We also show that spontaneous electroweak symmetry breaking
of the SM must take place on the TeV-brane.Comment: 62 pages, Latex, 22 figure
Effectiveness of Metyrapone in Treating Cushing's Syndrome: A Retrospective Multicenter Study in 195 Patients
Background:
Cushing's syndrome (CS) is a severe condition with excess mortality and significant morbidity necessitating control of hypercortisolemia. There are few data documenting use of the steroidogenesis inhibitor metyrapone for this purpose.
Objective:
The objective was to assess the effectiveness of metyrapone in controlling cortisol excess in a contemporary series of patients with CS.
Design:
This was designed as a retrospective, multicenter study.
Setting:
Thirteen University hospitals were studied.
Patients:
We studied a total of 195 patients with proven CS: 115 Cushing's disease, 37 ectopic ACTH syndrome, 43 ACTH-independent disease (adrenocortical carcinoma 10, adrenal adenoma 30, and ACTH-independent adrenal hyperplasia 3).
Measurements:
Measurements included biochemical parameters of activity of CS: mean serum cortisol “day-curve” (CDC) (target 150–300 nmol/L); 9 am serum cortisol; 24-hour urinary free cortisol (UFC).
Results:
A total of 164/195 received metyrapone monotherapy. Mean age was 49.6 ± 15.7 years; mean duration of therapy 8 months (median 3 mo, range 3 d to 11.6 y). There were significant improvements on metyrapone, first evaluation to last review: CDC (91 patients, 722.9 nmol/L [26.2 μg/dL] vs 348.6 nmol/L [12.6 μg/dL]; P < .0001); 9 am cortisol (123 patients, 882.9 nmol/L [32.0 μg/dL] vs 491.1 nmol/L [17.8 μg/dL]; P < .0001); and UFC (37 patients, 1483 nmol/24 h [537 μg/24 h] vs 452.6 nmol/24 h [164 μg/24 h]; P = .003). Overall, control at last review: 55%, 43%, 46%, and 76% of patients who had CDCs, UFCs, 9 am cortisol less than 331 nmol/L (12.0 μg/dL), and 9 am cortisol less than upper limit of normal/600 nmol/L (21.7 μg/dL). Median final dose: Cushing's disease 1375 mg; ectopic ACTH syndrome 1500 mg; benign adrenal disease 750 mg; and adrenocortical carcinoma 1250 mg. Adverse events occurred in 25% of patients, mostly mild gastrointestinal upset and dizziness, usually within 2 weeks of initiation or dose increase, all reversible.
Conclusions:
Metyrapone is effective therapy for short- and long-term control of hypercortisolemia in CS
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