Integrable structures in LGTs near the deconfinement transition

In this contribution we review some recent results about the emergence of 2D integrable systems in 3D Lattice Gauge Theories near the deconfinement transition. We focus on some concrete examples involving the flux tube thickness, the ratio of k-string tensions and Polyakov loops correlators in various models.Comment: 8 pages, Poster contribution to the XXVII International Symposium on Lattice Field Theory, July 26-31, 2009, Peking University, Beijing, Chin

Relevance of multiple-quasiparticle tunneling between edge states at \nu =p/(2np+1)

We present an explanation for the anomalous behavior in tunneling conductance and noise through a point contact between edge states in the Jain series $\nu=p/(2np+1)$, for extremely weak-backscattering and low temperatures [Y.C. Chung, M. Heiblum, and V. Umansky, Phys. Rev. Lett. {\bf{91}}, 216804 (2003)]. We consider edge states with neutral modes propagating at finite velocity, and we show that the activation of their dynamics causes the unexpected change in the temperature power-law of the conductance. Even more importantly, we demonstrate that multiple-quasiparticles tunneling at low energies becomes the most relevant process. This result will be used to explain the experimental data on current noise where tunneling particles have a charge that can reach $p$ times the single quasiparticle charge. In this paper we analyze the conductance and the shot noise to substantiate quantitatively the proposed scenario.Comment: 4 pages, 2 figure

Composite Fermions with Spin at ν=1/2ν=1/2

to be published in proceedings of Varenna Summer School "E. Fermi": Course CLI "Quantum phenomena in mesoscopic systems", July 2002This is the author accepted manuscript. The final version is available from IOS press via the DOI in this record.The model of Composite Fermions for describing interacting electrons in two dimensions in the presence of a magnetic field is described. In this model, charged Fermions are combined with an even number of magnetic flux quanta in such a way that the external magnetic field is compensated on the average for half filling of Landau levels and the interaction is incorporated into an effective mass of the new composite particles. The fluctuations of the Chern-Simons gauge field, which describes formally the flux attachment, induce new interactions between the Composite Fermions. The effective interaction is investigated with particular emphasis on the role of the electron spin at filling factor $\nu=1/2$. For a system with equal numbers of spin-up and spin-down electrons it is found that the dominant effective interaction is attractive in the spin-singlet channel. This can induce a ground state consisting of Cooper pairs of Composite Fermions that is separated from the excited states by a gap. The results are used to understand recent spin polarization measurements done in the region of the Fractional Quantum Hall Effect at different constant filling factors.Acknowledgment This work has been supported by the European Union via the TMR and RTN programmes (FMRX-CT98-0180, HPRN-CT2000-00144), by the Deutsche Forschungsgemeinschaft within the Schwerpunkt “Quanten-Hall-Effekt” of the Universit¨at Hamburg, and by the Italian MURST via PRIN00

Parametrization and Stress-Energy-Momentum Tensors in Metric Field Theories

We give an exposition of the parametrization method of Kuchar [1973] in the context of the multisymplectic approach to field theory, as presented in Gotay and Marsden [2008a]. The purpose of the formalism developed herein is to make any classical field theory, containing a metric as a sole background field, generally covariant (that is, "parametrized," with the spacetime diffeomorphism group as a symmetry group) as well as fully dynamic. This is accomplished by introducing certain "covariance fields" as genuine dynamic fields. As we shall see, the multimomenta conjugate to these new fields form the Piola-Kirchhoff version of the stress-energy-momentum tensor field, and their Euler-Lagrange equations are vacuously satisfied. Thus, these fields have no additional physical content; they serve only to provide an efficient means of parametrizing the theory. Our results are illustrated with two examples, namely an electromagnetic field and a Klein-Gordon vector field, both on a background spacetime.Comment: 13 pages, 1 figur

Neutral modes edge state dynamics through quantum point contacts

Dynamics of neutral modes for fractional quantum Hall states is investigated for a quantum point contact geometry in the weak-backscattering regime. The effective field theory introduced by Fradkin-Lopez for edge states in the Jain sequence is generalized to the case of propagating neutral modes. The dominant tunnelling processes are identified also in the presence of non-universal phenomena induced by interactions. The crossover regime in the backscattering current between tunnelling of single-quasiparticles and of agglomerates of p-quasiparticles is analysed. We demonstrate that higher order cumulants of the backscattering current fluctuations are a unique resource to study quantitatively the competition between different carrier charges. We find that propagating neutral modes are a necessary ingredient in order to explain this crossover phenomena.Comment: 28 pages, 5 figure

Maxwell-Chern-Simons Theory With Boundary

The Maxwell-Chern-Simons (MCS) theory with planar boundary is considered. The boundary is introduced according to Symanzik's basic principles of locality and separability. A method of investigation is proposed, which, avoiding the straight computation of correlators, is appealing for situations where the computation of propagators, modified by the boundary, becomes quite complex. For MCS theory, the outcome is that a unique solution exists, in the form of chiral conserved currents, satisfying a Kac-Moody algebra, whose central charge does not depend on the Maxwell term.Comment: 30 page

Konishi anomaly approach to gravitational F-terms

We study gravitational corrections to the effective superpotential in theories with a single adjoint chiral multiplet, using the generalized Konishi anomaly and the gravitationally deformed chiral ring. We show that the genus one correction to the loop equation in the corresponding matrix model agrees with the gravitational corrected anomaly equations in the gauge theory. An important ingrediant in the proof is the lack of factorization of chiral gauge invariant operators in presence of a supergravity background. We also find a genus zero gravitational correction to the superpotential, which can be removed by a field redefinition.Comment: 28 pages, uses JHEP3.cl

Correction induced by irrelevant operators in the correlators of the 2d Ising model in a magnetic field

We investigate the presence of irrelevant operators in the 2d Ising model perturbed by a magnetic field, by studying the corrections induced by these operators in the spin-spin correlator of the model. To this end we perform a set of high precision simulations for the correlator both along the axes and along the diagonal of the lattice. By comparing the numerical results with the predictions of a perturbative expansion around the critical point we find unambiguous evidences of the presence of such irrelevant operators. It turns out that among the irrelevant operators the one which gives the largest correction is the spin 4 operator T^2 + \bar T^2 which accounts for the breaking of the rotational invariance due to the lattice. This result agrees with what was already known for the correlator evaluated exactly at the critical point and also with recent results obtained in the case of the thermal perturbation of the model.Comment: 28 pages, no figure

A novel echocardiographic method closely agrees with cardiac magnetic resonance in the assessment of left ventricular function in infarcted mice

Cardiac Magnetic Resonance (CMR) is the gold standard for left ventricular (LV) function assessment in small rodents and, though echocardiography (ECHO) has been proposed as an alternative method, LV volumes may be underestimated when marked eccentric remodeling is present. In the present study we described a novel echocardiographic method and we tested the agreement with CMR for LV volumes and ejection fraction calculation in mice with experimental myocardial infarction. Sham-operated and infarcted mice, subjected to Coronary Artery Ligation, underwent ECHO and CMR. Volumes and ejection fraction were calculated by ECHO using a standard Simpson\u2019s modified method (ECHO pLAX) or a method from sequential parasternal short axis (ECHO pSAX) acquired mechanically by translating the probe every 1 mm along the left ventricle. The mean differences \ub11.96 standard deviation near to zero suggested close agreement between ECHO pSAX and CMR; contrarily ECHO pLAX agreement with CMR was lower. In addition, ECHO was three times shorter and cheaper (Relative cost difference: pLAX: 1266% and pSAX 1257%) than CMR. In conclusion, ECHO pSAX is a new, fast, cheap and accurate method for LV function assessment in mice