1,227 research outputs found
Quantization of Midisuperspace Models
We give a comprehensive review of the quantization of midisuperspace models.
Though the main focus of the paper is on quantum aspects, we also provide an
introduction to several classical points related to the definition of these
models. We cover some important issues, in particular, the use of the principle
of symmetric criticality as a very useful tool to obtain the required
Hamiltonian formulations. Two main types of reductions are discussed: those
involving metrics with two Killing vector fields and spherically symmetric
models. We also review the more general models obtained by coupling matter
fields to these systems. Throughout the paper we give separate discussions for
standard quantizations using geometrodynamical variables and those relying on
loop quantum gravity inspired methods.Comment: To appear in Living Review in Relativit
Combining symbiotic simulation systems with enterprise data storage systems for real-time decision-making
This is the author accepted manuscript. The final version is available from Taylor & Francis via the DOI in this recordA symbiotic simulation system (S3) enables interactions between a physical system and its computational model representation. To support operational decisions, an S3 uses real-time data from the physical system, which is gathered via sensors and saved in an enterprise data storage system (EDSS). Both real-time and historical data are then used as inputs to the different components of an S3. This paper proposes a generic system architecture for an S3 and discusses its integration within EDSSs. The paper also reviews the literature on S3 and analyses how these systems can be used for real-time decision-making.Erasmus
First order parent formulation for generic gauge field theories
We show how a generic gauge field theory described by a BRST differential can
systematically be reformulated as a first order parent system whose spacetime
part is determined by the de Rham differential. In the spirit of Vasiliev's
unfolded approach, this is done by extending the original space of fields so as
to include their derivatives as new independent fields together with associated
form fields. Through the inclusion of the antifield dependent part of the BRST
differential, the parent formulation can be used both for on and off-shell
formulations. For diffeomorphism invariant models, the parent formulation can
be reformulated as an AKSZ-type sigma model. Several examples, such as the
relativistic particle, parametrized theories, Yang-Mills theory, general
relativity and the two dimensional sigma model are worked out in details.Comment: 36 pages, additional sections and minor correction
Recommended from our members
Erratum to: 36th International Symposium on Intensive Care and Emergency Medicine: Brussels, Belgium. 15-18 March 2016.
[This corrects the article DOI: 10.1186/s13054-016-1208-6.]
Extremal and nonextremal Kerr/CFT correspondences
I rederive the Kerr/CFT correspondence without first taking the near-horizon
extremal Kerr limit. This method extends easily to nonextremal black holes, for
which the temperature and central charge behave poorly at the horizon but the
entropy remains finite. A computation yields one-half of the standard
Bekenstein-Hawking entropy, with hints that the other half may be related to a
conformal field theory at the inner horizon. I then present an alternative
approach, based on a stretched Killing horizon, in which the full entropy is
obtained and the temperature and central charge remain well-behaved even in the
nonextremal case.Comment: v3: missing term restored in eqn. (A.10) for central term; does not
affect conclusions of this paper, but important in other context
Quantum Gravity in 2+1 Dimensions: The Case of a Closed Universe
In three spacetime dimensions, general relativity drastically simplifies,
becoming a ``topological'' theory with no propagating local degrees of freedom.
Nevertheless, many of the difficult conceptual problems of quantizing gravity
are still present. In this review, I summarize the rather large body of work
that has gone towards quantizing (2+1)-dimensional vacuum gravity in the
setting of a spatially closed universe.Comment: 61 pages, draft of review for Living Reviews; comments, criticisms,
additions, missing references welcome; v2: minor changes, added reference
Socio-demographic determinants of coinfections by HIV, hepatitis B and hepatitis C viruses in central Italian prisoners
BACKGROUND: The coinfections HIV/HCV/HBV are an important health issue in penitentiary communities. The aim of the study was to examine HIV, HBV and HCV coinfections determinants amongst prisoners in the jails of Southern Lazio (Central Italy), in the period 1995-2000. METHODS: Diagnosis of seropositivities for HIV, HBV and HCV was made using ELISA method. A multiple logistic regression analysis was conducted to verify the influence of socio-demographic factors on the HIV/HBV/HCV coinfections. RESULTS: HIV/HCV, HBV/HCV and HIV/HBV coinfections were detected in 42 (4%), 203 (17.9%) and 31 (2.9%) inmates, respectively. These coinfections are significantly associated with the status of drug addiction (OR = 16.02; p = 0.012; OR = 4.15; p < 0.001; OR = 23.57; p = 0.002), smoking habits (OR = 3.73; p = 0.033; OR = 1.42; p = 0.088; OR = 4.25; p = 0.053) and Italian nationality (OR = 7.05; p = 0.009; OR = 2.31; p < 0.001; OR = 4.61; p = 0.04). CONCLUSION: The prevalence of HIV, HBV and HCV seropositivity in jails suggests that information and education programs for inmates could be useful to reduce the spread of such infections
Measurement of the Bottom-Strange Meson Mixing Phase in the Full CDF Data Set
We report a measurement of the bottom-strange meson mixing phase \beta_s
using the time evolution of B0_s -> J/\psi (->\mu+\mu-) \phi (-> K+ K-) decays
in which the quark-flavor content of the bottom-strange meson is identified at
production. This measurement uses the full data set of proton-antiproton
collisions at sqrt(s)= 1.96 TeV collected by the Collider Detector experiment
at the Fermilab Tevatron, corresponding to 9.6 fb-1 of integrated luminosity.
We report confidence regions in the two-dimensional space of \beta_s and the
B0_s decay-width difference \Delta\Gamma_s, and measure \beta_s in [-\pi/2,
-1.51] U [-0.06, 0.30] U [1.26, \pi/2] at the 68% confidence level, in
agreement with the standard model expectation. Assuming the standard model
value of \beta_s, we also determine \Delta\Gamma_s = 0.068 +- 0.026 (stat) +-
0.009 (syst) ps-1 and the mean B0_s lifetime, \tau_s = 1.528 +- 0.019 (stat) +-
0.009 (syst) ps, which are consistent and competitive with determinations by
other experiments.Comment: 8 pages, 2 figures, Phys. Rev. Lett 109, 171802 (2012
Jet energy measurement with the ATLAS detector in proton-proton collisions at root s=7 TeV
The jet energy scale and its systematic uncertainty are determined for jets measured with the ATLAS detector at the LHC in proton-proton collision data at a centre-of-mass energy of βs = 7TeV corresponding to an integrated luminosity of 38 pb-1. Jets are reconstructed with the anti-kt algorithm with distance parameters R=0. 4 or R=0. 6. Jet energy and angle corrections are determined from Monte Carlo simulations to calibrate jets with transverse momenta pTβ₯20 GeV and pseudorapidities {pipe}Ξ·{pipe}<4. 5. The jet energy systematic uncertainty is estimated using the single isolated hadron response measured in situ and in test-beams, exploiting the transverse momentum balance between central and forward jets in events with dijet topologies and studying systematic variations in Monte Carlo simulations. The jet energy uncertainty is less than 2. 5 % in the central calorimeter region ({pipe}Ξ·{pipe}<0. 8) for jets with 60β€pT<800 GeV, and is maximally 14 % for pT<30 GeV in the most forward region 3. 2β€{pipe}Ξ·{pipe}<4. 5. The jet energy is validated for jet transverse momenta up to 1 TeV to the level of a few percent using several in situ techniques by comparing a well-known reference such as the recoiling photon pT, the sum of the transverse momenta of tracks associated to the jet, or a system of low-pT jets recoiling against a high-pT jet. More sophisticated jet calibration schemes are presented based on calorimeter cell energy density weighting or hadronic properties of jets, aiming for an improved jet energy resolution and a reduced flavour dependence of the jet response. The systematic uncertainty of the jet energy determined from a combination of in situ techniques is consistent with the one derived from single hadron response measurements over a wide kinematic range. The nominal corrections and uncertainties are derived for isolated jets in an inclusive sample of high-pT jets. Special cases such as event topologies with close-by jets, or selections of samples with an enhanced content of jets originating from light quarks, heavy quarks or gluons are also discussed and the corresponding uncertainties are determined. Β© 2013 CERN for the benefit of the ATLAS collaboration
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