8,711 research outputs found
Phase transitions and adiabatic preparation of a fractional Chern insulator in a boson cold atom model
We investigate the fate of hardcore bosons in a Harper-Hofstadter model which
was experimentally realized by Aidelsburger et al. [Nature Physics 11 , 162
(2015)] at half filling of the lowest band. We discuss the stability of an
emergent fractional Chern insulator (FCI) state in a finite region of the phase
diagram that is separated from a superfluid state by a first-order transition
when tuning the band topology following the protocol used in the experiment.
Since crossing a first-order transition is unfavorable for adiabatically
preparing the FCI state, we extend the model to stabilize a featureless
insulating state. The transition between this phase and the topological state
proves to be continuous, providing a path in parameter space along which an FCI
state could be adiabatically prepared. To further corroborate this statement,
we perform time-dependent DMRG calculations which demonstrate that the FCI
state may indeed be reached by adiabatically tuning a simple product state.Comment: 7 pages, 7 figures, published versio
Diffractive dissociation into final states
The COMPASS fixed-target experiment at CERN/SPS is dedicated to the study of
hadron structure and spectroscopy, especially the search for spin-exotic
states. After having started to study the existence of the spin-exotic
resonance in the 2004 pilot-run data, the new 2008/09 data will
enable us to further clarify the situation. Apart from the
resonance, also a spin-exotic was reported in the past in the
decay channel by the E852/BNL experiment, however, this state
still lacks confirmation. We present a first event selection of the
diffractively produced system showing clean
and resonances at competing statistics. A partial-wave analysis
started on and decay channels will further
complete the search for spin-exotics in the 2008/09 COMPASS data.Comment: 4 pages, 6 figures, Hadron2011 Conference Proceedings, to appear in
the proceedings of the XIV International Conference on Hadron Spectroscopy:
Hadron 2011, Munich, Germany, 13-17 June 201
NLO QCD predictions for + jets production with Sherpa
We present precise predictions for prompt photon production in association
with a boson and jets. They are obtained within the Sherpa framework as a
consistently merged inclusive sample. Leptonic decays of the boson are
fully included in the calculation with all offshell effects. Virtual matrix
elements are provided by OpenLoops and parton shower effects are simulated with
a dipole parton shower. Thanks to the NLO QCD corrections included not only for
inclusive production but also for the + 1-jet process we
find significantly reduced systematic uncertainties and very good agreement
with experimental measurements at TeV. Predictions at
TeV are displayed including a study of theoretical uncertainties.
In view of an application of these simulations within LHC experiments, we
discuss in detail the necessary combination with a simulation of the + jets
final state. In addition to a corresponding prescription we introduce
recommended cross checks to avoid common pitfalls during the overlap removal
between the two samples.Comment: 20 pages, 15 Figure
Mutual information in classical spin models
The total many-body correlations present in finite temperature classical spin
systems are studied using the concept of mutual information. As opposed to
zero-temperature quantum phase transitions, the total correlations are not
maximal at the phase transition, but reach a maximum in the high temperature
paramagnetic phase. The Shannon and Renyi mutual information in both Ising and
Potts models in 2 dimensions are calculated numerically by combining matrix
product states algorithms and Monte Carlo sampling techniques
Impact of Specialization on Health Outcomes – Evidence from U.S. Cancer Data
There have been many studies of the volume-outcome relationship. In all of these, the unit of analysis is the hospital or physician. However, this level of analysis is mostly limited to the use of in-hospital mortality rates and is particularly sensitive to selective referral. Moreover, the literature on agglomeration economies highlights the importance of information spillovers within regions (Glaeser, 2010). To overcome these problems, our study is the first that examines the volume-outcome relationship on a regional (county or cancer registry) level. Using data from the National Cancer Institute’s Surveillance, Epidemiology and End Results program we find that regions with relatively more of the same cancer type exhibit relatively better health outcomes.Specialization, experience, cancer, survival
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