17476222
On Reduced Time Evolution for Initially Correlated Pure States
A new method to deal with reduced dynamics of open systems by means of the Schrodinger equation is presented. It allows one to consider the reduced time evolution for correlated and uncorrelated initial conditions.
115163135
Curing the UV/IR mixing for field theories with translation-invariant star products
The ultraviolet/infrared (UV/IR) mixing of noncommutative field theories has been recently shown to be a generic feature of translation- invariant associative products. In this paper we propose to take into account the quantum corrections of the model to modify in this way the noncommutative action. This idea was already used to cure the UV/IR mixing for theories on Moyal space. We show that in the present framework also, this proposal proves successful for curing the mixing. We achieve this task by explicit calculations of one and higher loops Feynman amplitudes. For the sake of completeness, we compute the form of the new action in the matrix base for the Wick-Voros product.
9251869
Probability representation in quantum field theory
Abstract The recently proposed probability representation of quantum mechanics is generalized to quantum field theory. We introduce a probability distribution functional for field configurations and find an evolution equation for such a distribution. The connection to the time-dependent generating functional of Green's functions is elucidated and the classical limit is discussed.
11091935
The beat of a fuzzy drum: fuzzy Bessel functions for the disc
The fuzzy disc is a matrix approximation of the functions on a disc which preserves rotational symmetry. In this paper we introduce a basis for the algebra of functions on the fuzzy disc in terms of the eigenfunctions of a properly defined fuzzy laplacian. In the commutative limit they tend to the eigenfunctions of the ordinary laplacian on the disc, i.e. Bessel functions of the first kind, thus deserving the name of fuzzy Bessel functions.
118914872
A field-theoretic approach to Spin Foam models in Quantum Gravity
We present an introduction to Group Field Theory models, motivating them on the basis of their relationship with discretized BF models of gravity. We derive the Feynmann rules and compute quantum corrections in the coherent states basis.
5552432
Critical exponents of the Gross-Neveu model from the effective average action.
The phase transition of the Gross-Neveu model with N fermions is investigated by means of a nonperturbative evolution equation for the scale dependence of the effective average action. The critical exponents and scaling amplitudes are calculated for various values of N in d = 3. It is also explicitly verified that the Neveu-Yukawa model belongs to the same universality class as the Gross-Neveu model.
122999968
Elemental analysis of aerosols collected at the Pierre Auger Cosmic Ray Observatory with PIXE technique complemented with SEM/EDX
Abstract The aim of this work is to characterize surface aerosols at the Pierre Auger Cosmic Ray Observatory located at Pampa Amarilla, near Malargue city, in the Andes region of Argentina, with experimental sampling techniques used for the first time in a cosmic ray observatory, adding to information provided by the existing Auger aerosol monitors. A good knowledge of the optical attenuation due to aerosols is crucial for a good reconstruction of the signals from cosmic ray showers detected by the fluorescence detectors of the Observatory. Aerosols were collected in filters, during the Southern Hemisphere winter and spring in 2008. Concentrations in PM2.5 and PM2.5–10 filters were determined by gravimetric analysis and their elemental composition by the PIXE technique, complemented with SEM/EDX. Low aerosol concentrations were measured during the sampling period. The mean total mass PM10 (=PM2.5 + PM2.5–10 fractions) value was [mean(se)] 9.8(1.0) μg/m3 [sd = 5.9 μg/m3]. The mean PM10 value during winter was 7(1.1) μg/m3 [sd = 4.5 μg/m3], about half of the 13.1(1.5) [sd = 5.7 μg/m3] measured during springtime. The PM2.5 fraction was approximately 30% of the PM10 fraction. PIXE results gave levels of S, Cl, K, Ca, Ti, Mn, Fe in the analyzed aerosol samples, showing that these elements correspond to 25% and 13% of the PM2.5 and PM2.5–10 total mass respectively. The rest of the mass was due to the elements with low Z (below 16) which cannot be detected by our X-ray setup. Comparison with SEM/EDX analysis showed that most of them were Si and Al (aluminosilicates). Our results indicate that most of the aerosols at the Auger Observatory would most likely come from the soil of the region. Due to its vast atmospheric monitoring network, the Auger Observatory is an interesting reference site for further atmospheric studies.