546 research outputs found
The Hierarchy Principle and the Large Mass Limit of the Linear Sigma Model
In perturbation theory we study the matching in four dimensions between the
linear sigma model in the large mass limit and the renormalized nonlinear sigma
model in the recently proposed flat connection formalism. We consider both the
chiral limit and the strong coupling limit of the linear sigma model. Our
formalism extends to Green functions with an arbitrary number of pion legs,at
one loop level,on the basis of the hierarchy as an efficient unifying principle
that governs both limits. While the chiral limit is straightforward, the
matching in the strong coupling limit requires careful use of the normalization
conditions of the linear theory, in order to exploit the functional equation
and the complete set of local solutions of its linearized form.Comment: Latex, 41 pages, corrected typos, final version accepted by IJT
High field cardiac magnetic resonance imaging: a case for ultrahigh field cardiac magnetic resonance
Muon-induced background to proton decay in the p→K+ν decay channel with large underground liquid argon TPC detectors
Large liquid argon TPC detector programs such as LBNE and LAGUNA-LBNO will be able to make measurements of the proton lifetime which will outperform Cherenkov detectors in the proton decay channel p→K+ν. At the large depths which are proposed for such experiments, a non-negligible source of isolated charged kaons may be produced in the showers of cosmogenic muons. We present an estimate of the cosmogenic muon background to proton decay in the p→K+ν channel. The simulation of muon transport to a depth of 4 km w.e. is performed in the MUSIC framework and the subsequent propagation of muons and secondary particles in the vicinity of a cylindrical 20 kt LAr target is performed using Geant4. An exposure time of 100 years is considered, with a rate of <0.0012 events/kt/year at 90% CL predicted from our simulations
LHC as and Collider
We propose an experiment at the LHC with leading neutron production.The
latter can be used to extract from it the total cross-sections. With
two leading neutrons we can get access to the total
cross-sections. In this note we give some estimates and discuss related
problems and prospects.Comment: 22 pages, 18 figures, 8 tables, to be publishe
Confronting models on cosmic ray interactions with particle physics at LHC energies
Inelastic pp collisions are dominated by soft (low momentum transfer) physics
where perturbative QCD cannot be fully applied. A deep understanding of both
soft and semi-hard processes is crucial for predictions of minimum bias and
underlying events of the now coming on line pp Large Hadron Collider (LHC).
Moreover, the interaction of cosmic ray particles entering in the atmosphere is
extremely sensitive to these soft processes and consequently cannot be
formulated from first principles. Because of this, air shower analyses strongly
rely on hadronic interaction models, which extrapolate collider data several
orders of magnitude. A comparative study of Monte Carlo simulations of pp
collisions (at the LHC center-of-mass energy ~ 14 TeV) using the most popular
hadronic interaction models for ultrahigh energy cosmic ray (SIBYLL and QGSJET)
and for collider physics (the PYTHIA multiparton model) is presented. The most
relevant distributions are studied including those observables from diffractive
events with the aim of discriminating between the different models.Comment: 8 pages revtex, 8 figures, added reference
Solving matrix models using holomorphy
We investigate the relationship between supersymmetric gauge theories with
moduli spaces and matrix models. Particular attention is given to situations
where the moduli space gets quantum corrected. These corrections are controlled
by holomorphy. It is argued that these quantum deformations give rise to
non-trivial relations for generalized resolvents that must hold in the
associated matrix model. These relations allow to solve a sector of the
associated matrix model in a similar way to a one-matrix model, by studying a
curve that encodes the generalized resolvents. At the level of loop equations
for the matrix model, the situations with a moduli space can sometimes be
considered as a degeneration of an infinite set of linear equations, and the
quantum moduli space encodes the consistency conditions for these equations to
have a solution.Comment: 38 pages, JHEP style, 1 figur
Myocardial effective transverse relaxation time T(2)* is elevated in hypertrophic cardiomyopathy: a 7.0 T magnetic resonance imaging study
Hypertrophic cardiomyopathy (HCM) is the most common genetic disease of the myocardium and bares the risk of progression to heart failure or sudden cardiac death. Identifying patients at risk remains an unmet need. Recognizing the dependence of microscopic susceptibility on tissue microstructure and on cardiac macromorphology we hypothesized that myocardial T2* might be altered in HCM patients compared to healthy controls. To test this hypothesis, myocardial T2*-mapping was conducted at 7.0 Tesla to enhance T2*-contrast. 2D CINE T2*-mapping was performed in healthy controls and HCM patients. To ensure that T2* is not dominated by macroscopic magnetic field inhomogeneities, volume selective B0 shimming was applied. T2* changes in the interventricular septum across the cardiac cycle were analyzed together with left ventricular radius and ventricular septal wall thickness. The results show that myocardial T2* is elevated throughout the cardiac cycle in HCM patients compared to healthy controls. A mean septal T2* = 13.7 ± 1.1 ms (end-systole: T2*,systole = 15.0 ± 2.1, end-diastole: T2*,diastole = 13.4 ± 1.3 ms, T2*,systole/T2*,diastole ratio = 1.12) was observed in healthy controls. For HCM patients a mean septal T2* = 17.4 ± 1.4 ms (end-systole: T2*,systole = 17.7 ± 1.2 ms, end-diastole: T2*,diastole = 16.2 ± 2.5 ms, T2*,systole/T2*,diastole ratio = 1.09) was found. Our preliminary results provide encouragement that assessment of T2* and its changes across the cardiac cycle may benefit myocardial tissue characterization in HCM
Note on Matrix Model with Massless Flavors
In this note, following the work of Seiberg in hep-th/0211234 for the
conjecture between the field theory and matrix model in the case with massive
fundamental flavors, we generalize it to the case with massless fundamental
flavors. We show that with a little modifications, the analysis given by
Seiberg can be used directly to the case of massless flavors. Furthermore, this
new method explains the insertion of delta functions in the matrix model given
by Demasure and Janik in hep-th/0211082.Comment: 10 pages. Type fixed. Remarks adde
Guidelines for training in cardiovascular magnetic resonance (CMR)
These "Guidelines for training in Cardiovascular Magnetic Resonance" were developed by the Certification Committee of the Society for Cardiovascular Magnetic Resonance (SCMR) and approved by the SCMR Board of Trustees
AEGIS at CERN: Measuring Antihydrogen Fall
The main goal of the AEGIS experiment at the CERN Antiproton Decelerator is
the test of fundamental laws such as the Weak Equivalence Principle (WEP) and
CPT symmetry. In the first phase of AEGIS, a beam of antihydrogen will be
formed whose fall in the gravitational field is measured in a Moire'
deflectometer; this will constitute the first test of the WEP with antimatter.Comment: Presented at the Fifth Meeting on CPT and Lorentz Symmetry,
Bloomington, Indiana, June 28-July 2, 201
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