29885643
Anomalous Behavior in an Effective Model of Graphene with Coulomb Interactions
We analyze by exact Renormalization Group (RG) methods the infrared properties of an effective model of graphene, in which two-dimensional (2D) massless Dirac fermions propagating with a velocity smaller than the speed of light interact with a 3D quantum electromagnetic field. The fermionic correlation functions are written as series in the running coupling constants, with finite coefficients that admit explicit bounds at all orders. The implementation of Ward Identities in the RG scheme implies that the effective charges tend to a line of fixed points. At small momenta, the quasi-particle weight tends to zero and the effective Fermi velocity tends to a finite value. These limits are approached with a power law behavior characterized by non-universal critical exponents.
17981665
Absolute stability limit for relativistic charged spheres
We find an exact solution for the stability limit of relativistic charged spheres for the case of constant gravitational mass density and constant charge density. We argue that this provides an absolute stability limit for any relativistic charged sphere in which the gravitational mass density decreases with radius and the charge density increases with radius. We then provide a cruder absolute stability limit that applies to any charged sphere with a spherically symmetric mass and charge distribution. We give numerical results for all cases. In addition, we discuss the example of a neutral sphere surrounded by a thin, charged shell.
337931
The Scaling limit of the energy correlations in non integrable Ising models
We obtain an explicit expression for the multipoint energy correlations of a non solvable two-dimensional Ising models with nearest neighbor ferromagnetic interactions plus a weak finite range interaction of strength �, in a scaling limit in which we send the lattice spacing to zero and the temperature to the critical one. Our analysis is based on an exact mapping of the model into an interacting lattice fermionic theory, which generalizes the one originally used by Schultz, Mattis and Lieb for the nearest neighbor Ising model. The interacting model is then analyzed by a multiscale method first proposed by Pinson and Spencer. If the lattice spacing is finite, then the correlations cannot be computed in closed form: rather, they are expressed in terms of infinite, convergent, power series in �. In the scaling limit, these infinite expansions radically simplify and reduce to the limiting energy correlations of the integrable Ising model, up to a finite renormalization of the parameters. Explicit bounds on the speed of convergence to the scaling limit are derived.
14496666
Lattice gauge theory model for graphene
The effects of the electromagnetic (em) electron-electron interactions in half-filled graphene are investigated in terms of a lattice gauge theory model. By using exact renormalization group methods and lattice Ward identities, we show that the em interactions amplify the responses to the excitonic pairings associated to a Kekule distortion and to a charge-density wave. The effect of the electronic repulsion on the Peierls-Kekule instability, usually neglected, is evaluated by deriving an exact non BCS gap equation, from which we find evidence that strong em interactions among electrons facilitate the spontaneous distortion of the lattice and the opening of a gap.
62170783
Terra Incognita 2: Exploring and Modeling Absolute Masses
After drawing the context of discussion of this parallel session, we offer a summary of the various contributions, and comment on future perspectives. We include only the few references that are useful for the discussion, and refer to the individual contributions for a complete bibliography on the related subjects.
126109680
Bolometric light detectors for Neutrinoless Double Beta Decay search
Margherita TENCONI∗,ab Dmitry CHERNYAK,abc Fedor DANEVICH,c Andrea GIULIANI,ad Michele MANCUSO,ad Stefanos MARNIEROS,a Emiliano OLIVIERI,a Claudia RUSCONIde aCentre de Spectrometrie Nucleaire et de Spectrometrie de Masse F-91405 Orsay, France bUniversite Paris-Sud F-91405 Orsay, France cInstitute for Nuclear Research MSP 0368 Kyiv, Ukraine dUniversita degli Studi dell’Insubria, Dipartimento di Fisica e Matematica I-22100 Como, Italy eIstituto Nazionale di Fisica Nucleare, Sezione di Milano-Bicocca I-20126 Milano, Italy
121148985
Neutrinoless Double-Beta Decay
This paper introduces the neutrinoless double-beta decay (the rarest nuclear weak process) and 
describes the status of the research for this transition, both from the point of view of theoretical 
nuclear physics and in terms of the present and future experimental scenarios. Implications of this 
phenomenon on crucial aspects of particle physics are briefly discussed. The calculations of the nuclear 
matrix elements in case of mass mechanisms are reviewed, and a range for these quantities is proposed 
for the most appealing candidates. After introducing general experimental concepts—such as the 
choice of the best candidates, the different proposed technological approaches, and the sensitivity—we make the point on the experimental situation. Searches running or in preparation are described, providing an organic presentation which picks up similarities and differences. A critical comparison of 
the adopted technologies and of their physics reach (in terms of sensitivity to the effective Majorana 
neutrino mass) is performed. As a conclusion, we try to envisage what we expect round the corner 
and at a longer time scale.
55583008
Effect of SiO2 coating in bolometric Ge light detectors for rare event searches
In germanium-based light detectors for scintillating bolometers, a SiO2 anti-reflective coating is often applied on the side of the germanium wafer exposed to light with the aim to improve its light collection efficiency. In this paper, we report about a measurement, performed in the temperature range 25 35 mK, of the light-collection increase obtained thanks to this method, which resulted to be of the order of 20%. The procedure followed has been carefully selected in order to minimize systematic effects. The employed light sources have the same spectral features (peaking at � 630 nm wavelength) that will characterise future neutrinoless double beta decay experiments on the isotope 82 Se and based on ZnSe crystals, such as LUCIFER. The coupling between source and light detector reproduces the configuration used in scintillating bolometers. The present measurement clarifies the role of SiO2 coating and describes a method and a set-up that can be extended to the study of other types of coatings and luminescent materials.
119023109
A “must” for a double beta decay experiment: the reduction of the background
The main goal of the next generation neutrinoless double beta decay (0νββ) experiments will be the investigation of the inverse hierarchy region of the neutrino mass pattern. One of the major challenges for these experiments is to greatly reduce the background in order to reach the required sensitivity. In this work we report some results obtained with a new technique that, exploiting the dynamic of the heat flow in the detector, gives us information on the particle impact point providing a new means for an active background discrimination.