6,288 research outputs found

    Multigap RPC time resolution to 511 keV annihilation photons

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    The time resolution of Multigap Resistive Plate Counters (MRPCs) to 511511 keV gamma rays has been investigated using a 22^{22}Na source and four detectors. The MRPCs time resolution has been derived from the Time-of-Flight information, measured from pairs of space correlated triggered events. A GEANT4 simulation has been performed to analyze possible setup contributions and to support experimental results. A time resolution (FWHM) of 376376 ps and 312312 ps has been measured for a single MRPC with four 250250 ÎĽ\mum gas gaps by considering respectively one and two independent pairs of detectors.Comment: 25 pages, 14 figure

    QGP Susceptibilities from PNJL Model

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    An improved version of the PNJL model is used to calculate various thermodynamical quantities, {\it viz.}, quark number susceptibility, isospin susceptibility, specific heat, speed of sound and conformal measure. Comparison with Lattice data is found to be encouraging.Comment: 4 pages, 2 figures, poster presented at Quark Matter'0

    Polyakov Loop and Gluon Quasiparticles in Yang-Mills Thermodynamics

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    We study the interpretation of Lattice data about the thermodynamics of the deconfinement phase of SU(3) Yang-Mills theory, in terms of gluon quasiparticles propagating in a background of a Polyakov loop. A potential for the Polyakov loop, inspired by the strong coupling expansion of the QCD action, is introduced; the Polyakov loop is coupled to tranverse gluon quasiparticles by means of a gas-like effective potential. This study is useful to identify the effective degrees of freedom propagating in the gluon medium above the critical temperature. A main general finding is that a dominant part of the phase transition dynamics is accounted for by the Polyakov loop dynamics, hence the thermodynamics can be described without the need for diverging or exponentially increasing quasiparticle masses as T→TcT \rightarrow T_c, at variance respect to standard quasiparticle models.Comment: 8 pages, 9 figure

    Compact Stars - How Exotic Can They Be?

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    Strong interaction physics under extreme conditions of high temperature and/or density is of central interest in modern nuclear physics for experimentalists and theorists alike. In order to investigate such systems, model approaches that include hadrons and quarks in a unified approach, will be discussed. Special attention will be given to high-density matter as it occurs in neutron stars. Given the current observational limits for neutron star masses, the properties of hyperonic and hybrid stars will be determined. In this context especially the question of the extent, to which exotic particles like hyperons and quarks affect star masses, will be discussed.Comment: Contributon to conference "Nuclear Physics: Present and Future", held in Boppard (Germany), May 201

    Fast and Sensitive Detection of Soil-Borne Cereal Mosaic Virus in Leaf Crude Extract of Durum Wheat

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    Soil-borne cereal mosaic virus (SBCMV) is a furovirus with rigid rod-shaped particles containing an ssRNA genome, transmitted by Polymyxa graminis Led., a plasmodiophorid that can persist in soil for up to 20 years. SBCMV was reported on common and durum wheat and it can cause yield losses of up to 70%. Detection protocols currently available are costly and time-consuming (real-time PCR) or have limited sensitivity (ELISA). To facilitate an efficient investigation of the real dispersal of SBCMV, it is necessary to develop a new detection tool with the following characteristics: no extraction steps, very fast results, and high sensitivity to allow pooling of a large number of samples. In the present work, we have developed a reverse transcription loop-mediated isothermal amplification (RT-LAMP) protocol with such characteristics, and we have compared it with real-time PCR. Our results show that the sensitivity of LAMP and real-time PCR on cDNA and RT-LAMP on crude extracts are comparable, with the obvious advantage that RT-LAMP produces results in minutes rather than hours. This paves the way for extensive field surveys, leading to a better knowledge of the impact of this virus on wheat health and yield

    Towards the automation of the Local Analytic Sector subtraction

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    We present the state of the art of the Local Analytic Sector subtraction. The scheme is now complete at NLO in the massless case for the treatment of initial- and final-state radiations. Its flexibility has been improved by the introduction of damping factors, which can be tuned to reduce numerical instabilities, though preserving the simplicity of the algorithm. The same degree of universality has been reached at NNLO for final-state radiation, where we derived fully analytic and compact results for all integrated counterterms. This allows us to explicitly check the cancellation of the virtual infrared singularities in generic processes with massless final-state partons

    An effective chiral Hadron-Quark Equation of State

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    We construct an effective model for the QCD equation of state, taking into account chiral symmetry restoration as well as the deconfinement phase transition. The correct asymptotic degrees of freedom at the high and low temperature limits are included (quarks ↔\leftrightarrow hadrons). The model shows a rapid crossover for both order parameters, as is expected from lattice calculations. We then compare the thermodynamic properties of the model at μB=0\mu_B=0 which turn out to be in qualitative agreement with lattice data, while apparent quantitative differences can be attributed to hadronic contributions and excluded volume corrections. Furthermore we discuss the effects of a repulsive vector type quark interaction at finite baryon number densities on the resulting phase diagram of the model. Our current model is able to reproduce a first-order liquid gas phase transition as expected, but does not show any signs of a first order deconfinement or chiral phase transition. Both transitions rather appear as a very wide crossover in which heavily medium modified hadron coexist with free quarks.Comment: 19 pages, 13 figures Version accepted by J. Phys.

    Thermodynamics of the PNJL model

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    QCD thermodynamics is investigated by means of the Polyakov-loop-extended Nambu Jona-Lasinio (PNJL) model, in which quarks couple simultaneously to the chiral condensate and to a background temporal gauge field representing Polyakov loop dynamics. The behaviour of the Polyakov loop as a function of temperature is obtained by minimizing the thermodynamic potential of the system. A Taylor series expansion of the pressure is performed. Pressure difference and quark number density are then evaluated up to sixth order in quark chemical potential, and compared to the corresponding lattice data. The validity of the Taylor expansion is discussed within our model, through a comparison between the full results and the truncated ones.Comment: 6 pages, 5 figures, Talk given at the Workshop for Young Scientists on the Physics of Ultrarelativistic Nucleus-Nucleus Collisions (Hot Quarks 2006), Villasimius, Italy, 15-20 May 200
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