Chromomagnetic Instability and Gluonic Phase at Nonzero Temperature

We describe the results of recent studies of a chromomagnetic instability and a gluonic phase in neutral two-flavor quark matter at nonzero temperature.Comment: 6 pages, 3 figures, prepared for International Workshop on Quantum Chromodynamics: QCD@Work 2007, Martina Franca, Valle d'Itria, Italy, 16-20 Jun 200

Observation of a New Fluxon Resonant Mechanism in Annular Josephson Tunnel Structures

A novel dynamical state has been observed in the dynamics of a perdurbed sine-Gordon system. This resonant state, has been experimentally observed as a singularity in the dc current voltage characteristic of an annular Josephson tunnel junction, excited in the presence of a magnetic field. With this respect, it can be assimilated to self-resonances known as Fiske steps. Differently from these, however, we demonstrate, on the basis of numerical simulations, that its detailed dynamics involves rotating fluxon pairs, a mechanism associated, so far, to self-resonances known as zero-field steps.Comment: 4 pages, 2 figures, submitted to Physical Review Letter

Heterogeneous response to immunotherapy in a patient with tonsillar squamous cell carcinoma assessed by18f-fdg pet/ct

Tonsillar carcinoma is the second most common malignancy of the head and neck region, with Squamous Cell Carcinoma (TSCC) as the most common histological type (>90%). For the advanced stage of TSCC, radiotherapy with or without platinum-based chemotherapy is the only therapeutic option. Immuno-checkpoint inhibitors (ICIs), in particular Nivolumab, considerably improves clinical management of these patients, but the response can be unpredictable. Difficulties can be encountered in evaluating response to immunotherapy, especially with morphological imaging, which can show an atypical response, such as pseudo-progression, leading to a premature discontinuation. Conversely, metabolic imaging can guide a more properly therapeutic decision. We present a case of a 71-year-old man affected by TSCC, treated with chemotherapy, radiotherapy, and Nivolumab as the last line of treatment. Pre-and post-immunotherapy18F-FDG PET/CT showed an impressive response, avoiding early drug discontinuation and ensuring better management of this patient

Exactly solvable models in 2D semiclassical dilaton gravity and extremal black holes

Previously known exactly solvable models of 2D semiclassical dilaton gravity admit, in the general case, only non-extreme black holes. It is shown that there exist exceptional degenerate cases, that can be obtained by some limiting transitions from the general exact solution, which include, in particular, extremal and ultraextremal black holes. We also analyze properties of extreme black holes without demanding exact solvability and show that for such solutions quantum backreaction forbids the existence of ultraextreme black holes. The conditions,under which divergencies of quantum stresses in a free falling frame can disappear, are found. We derive the closed equation with respect to the metric as a function of the dilaton field that enables one, choosing the form of the metric, to restore corresponding Lagrangian. It is demonstrated that exactly solvable models, found earlier, can be extended to include an electric charge only in two cases: either the dilaton-gravitation coupling is proportional to the potential term, or the latter vanishes. The second case leads to the effective potential with a negative amplitude and we analyze, how this fact affects the structure of spacetime. We also discuss the role of quantum backreaction in the relationship between extremal horizons and the branch of solutions with a constant dilaton.Comment: 31 pages. In v.2 typo in Ref. [2] corrected, 4 references added. Accepted in Class. Quant. Gra

Chern-Simons Field Theories with Non-semisimple Gauge Group of Symmetry

Subject of this work is a class of Chern-Simons field theories with non-semisimple gauge group, which may well be considered as the most straightforward generalization of an Abelian Chern-Simons field theory. As a matter of fact these theories, which are characterized by a non-semisimple group of gauge symmetry, have cubic interactions like those of non-abelian Chern-Simons field theories, but are free from radiative corrections. Moreover, at the tree level in the perturbative expansion,there are only two connected tree diagrams, corresponding to the propagator and to the three vertex originating from the cubic interaction terms. For such theories it is derived here a set of BRST invariant observables, which lead to metric independent amplitudes. The vacuum expectation values of these observables can be computed exactly. From their expressions it is possible to isolate the Gauss linking number and an invariant of the Milnor type, which describes the topological relations among three or more closed curves.Comment: 16 pages, 1 figure, plain LaTeX + psfig.st

Aging and Holography

Aging phenomena are examples of `non-equilibrium criticality' and can be exemplified by systems with Galilean and scaling symmetries but no time translation invariance. We realize aging holographically using a deformation of a non-relativistic version of gauge/gravity duality. Correlation functions of scalar operators are computed using holographic real-time techniques, and agree with field theory expectations. At least in this setup, general aging phenomena are reproduced holographically by complexifying the bulk space-time geometry, even in Lorentzian signature.Comment: 1 pdf figur

Closed strings in Misner space: a toy model for a Big Bounce ?

Misner space, also known as the Lorentzian orbifold $R^{1,1}/boost$, is one of the simplest examples of a cosmological singularity in string theory. In this lecture, we review the semi-classical propagation of closed strings in this background, with a particular emphasis on the twisted sectors of the orbifold. Tree-level scattering amplitudes and the one-loop vacuum amplitude are also discussed.Comment: 30 pages, 3 figures, to appear in the Proceedings of the NATO ASI and EC Summer School ``String Theory: from Gauge Interactions to Cosmology'', Cargese, France, June 7-19, 200

Thermodynamics of doubly charged CGHS model and D1-D5-KK black holes of IIB supergravity

We study the doubly charged Callan-Giddings-Harvey-Strominger (CGHS) model, which has black hole solutions that were found to be U-dual to the D1-D5-KK black holes of the IIB supergravity. We derive the action of the model via a spontaneous compactification on S^3 of the IIB supergravity on S^1*T^4 and obtain the general static solutions including black holes corresponding to certain non-asymptotically flat black holes in the IIB supergravity. Thermodynamics of them is established by computing the entropy, temperature, chemical potentials, and mass in the two-dimensional setup, and the first law of thermodynamics is explicitly verified. The entropy is in precise agreement with that of the D1-D5-KK black holes, and the mass turns out to be consistent with the infinite Lorentz boost along the M theory circle that is a part of the aforementioned U-dual chain.Comment: 21 pages, Revte

Open strings in relativistic ion traps

Electromagnetic plane waves provide examples of time-dependent open string backgrounds free of $\alpha'$ corrections. The solvable case of open strings in a quadrupolar wave front, analogous to pp-waves for closed strings, is discussed. In light-cone gauge, it leads to non-conformal boundary conditions similar to those induced by tachyon condensates. A maximum electric gradient is found, at which macroscopic strings with vanishing tension are pair-produced -- a non-relativistic analogue of the Born-Infeld critical electric field. Kinetic instabilities of quadrupolar electric fields are cured by standard atomic physics techniques, and do not interfere with the former dynamic instability. A new example of non-conformal open-closed duality is found. Propagation of open strings in time-dependent wave fronts is discussed.Comment: 43 pages, 11 figures, Latex2e, JHEP3.cls style; v2: one-loop amplitude corrected, open-closed duality proved, refs added, miscellaneous improvements, see historical note in fil

Glassy Random Matrix Models

This paper discusses Random Matrix Models which exhibit the unusual phenomena of having multiple solutions at the same point in phase space. These matrix models have gaps in their spectrum or density of eigenvalues. The free energy and certain correlation functions of these models show differences for the different solutions. Here I present evidence for the presence of multiple solutions both analytically and numerically. As an example I discuss the double well matrix model with potential $V(M)= -{\mu \over 2}M^2+{g \over 4}M^4$ where $M$ is a random $N\times N$ matrix (the $M^4$ matrix model) as well as the Gaussian Penner model with $V(M)={\mu\over 2}M^2-t \ln M$. First I study what these multiple solutions are in the large $N$ limit using the recurrence coefficient of the orthogonal polynomials. Second I discuss these solutions at the non-perturbative level to bring out some differences between the multiple solutions. I also present the two-point density-density correlation functions which further characterizes these models in a new university class. A motivation for this work is that variants of these models have been conjectured to be models of certain structural glasses in the high temperature phase.Comment: 25 pages, Latex, 7 Figures, to appear in PR