6,855 research outputs found
Complexity in parametric Bose-Hubbard Hamiltonians and structural analysis of eigenstates
We consider a family of chaotic Bose-Hubbard Hamiltonians (BHH) parameterized
by the coupling strength between neighboring sites. As increases the
eigenstates undergo changes, reflected in the structure of the Local Density of
States. We analyze these changes, both numerically and analytically, using
perturbative and semiclassical methods. Although our focus is on the quantum
trimer, the presented methodology is applicable for the analysis of longer
lattices as well.Comment: 4 pages, 4 figure
Predictors of course and outcome in hypochondriasis after cognitive-behavioral treatment
Background. Predictors of treatment outcome were evaluated in a clinical sample suffering from hypochondriasis. Methods: The sample consisted of 96 patients with hypochondriacal disorder according to DSM-IV or high syndrome scores on the Illness Attitude Scales (IAS) or Whiteley Index (WI). After intense inpatient cognitive-behavioral treatment (CBT), 60% of the patients were classified as responders because of substantial improvements or recovery from hypochondriacal symptomatology. Results: Non-responders were characterized by a higher degree of pre-treatment hypochondriasis, more somatization symptoms and general psychopathology (SCL-90R), more dysfunctional cognitions related to bodily functioning, higher levels of psychosocial impairments, and more utilization of the health care system as indicated by the number of hospital days and costs for inpatient treatments and medication. No predictive value was found for sociodemographic variables, comorbidity with other mental disorders and chronicity. Multiple linear regression showed that pre-treatment variables significantly predicted IAS scores at post-treatment (R-2 = 0.59), changes during treatment (0.10), IAS scores at follow-up two years later (0.41) and changes between baseline and follow-up (0.25). Conclusions: The results demonstrate the relevance of various psychopathological variables and health care utilization as important indicators for outcome and further course of clinical hypochondriasis. Copyright (C) 2002 S. Karger AG, Basel
Controlled quantum stirring of Bose-Einstein condensates
By cyclic adiabatic change of two control parameters of an optical trap one
can induce a circulating current of condensed bosons. The amount of particles
that are transported per period depends on the "radius" of the cycle, and this
dependence can be utilized in order to probe the interatomic interactions. For
strong repulsive interaction the current can be regarded as arising from a
sequence of Landau-Zener crossings. For weaker interaction one observes either
gradual or coherent mega crossings, while for attractive interaction the
particles are glued together and behave like a classical ball. For the analysis
we use the Kubo approach to quantum pumping with the associated Dirac monopoles
picture of parameter space.Comment: 12 pages, 8 figure
A large Muon Electric Dipole Moment from Flavor?
We study the prospects and opportunities of a large muon electric dipole
moment (EDM) of the order (10^{-24} - 10^{-22}) ecm. We investigate how natural
such a value is within the general minimal supersymmetric extension of the
Standard Model with CP violation from lepton flavor violation in view of the
experimental constraints. In models with hybrid gauge-gravity mediated
supersymmetry breaking a large muon EDM is indicative for the structure of
flavor breaking at the Planck scale, and points towards a high messenger scale.Comment: 12 pages, 12 figures. v3: References and Eq 28 fixed; conclusions
unchange
Two-dimensional super Yang-Mills theory investigated with improved resolution
In earlier work, N=(1,1) super Yang--Mills theory in two dimensions was found
to have several interesting properties, though these properties could not be
investigated in any detail. In this paper we analyze two of these properties.
First, we investigate the spectrum of the theory. We calculate the masses of
the low-lying states using the supersymmetric discrete light-cone (SDLCQ)
approximation and obtain their continuum values. The spectrum exhibits an
interesting distribution of masses, which we discuss along with a toy model for
this pattern. We also discuss how the average number of partons grows in the
bound states. Second, we determine the number of fermions and bosons in the
N=(1,1) and N=(2,2) theories in each symmetry sector as a function of the
resolution. Our finding that the numbers of fermions and bosons in each sector
are the same is part of the answer to the question of why the SDLCQ
approximation exactly preserves supersymmetry.Comment: 20 pages, 10 figures, LaTe
- …