6,975 research outputs found
Gluon saturation and the Froissart bound: a simple approach
At very high energies we expect that the hadronic cross sections satisfy the
Froissart bound, which is a well-established property of the strong
interactions. In this energy regime we also expect the formation of the Color
Glass Condensate, characterized by gluon saturation and a typical momentum
scale: the saturation scale . In this paper we show that if a saturation
window exists between the nonperturbative and perturbative regimes of Quantum
Chromodynamics (QCD), the total cross sections satisfy the Froissart bound.
Furthermore, we show that our approach allows us to describe the high energy
experimental data on total cross sections.Comment: 6 pages, 5 figures. Includes additional figures, discussion and
reference
Gluon saturation and Feynman scaling in leading neutron production
In this paper we extend the color dipole formalism to the study of leading
neutron production in collisions at high energies
and estimate the related observables, which were measured at HERA and may be
analysed in future electron-proton () colliders. In particular, we
calculate the Feynman distribution of leading neutrons, which is
expressed in terms of the pion flux and the photon-pion total cross section. In
the color dipole formalism, the photon-pion cross section is described in terms
of the dipole-pion scattering amplitude, which contains information about the
QCD dynamics at high energies and gluon saturation effects. We consider
different models for the scattering amplitude, which have been used to describe
the inclusive and diffractive HERA data. Moreover, the model dependence of
our predictions with the description of the pion flux is analysed in detail. We
show that the recently released H1 leading neutron spectra can be reproduced
using the color dipole formalism and that these spectra could help us to
observe more clearly gluon saturation effects in future colliders.Comment: 10 pages, 5 figure
Tetraquark Production in Double Parton Scattering
We develop a model to study tetraquark production in hadronic collisions. We
focus on double parton scattering and formulate a version of the color
evaporation model for the production of the and of the
tetraquark, a state composed by the quarks. We find that
the production cross section grows rapidly with the collision energy
and make predictions for the forthcoming higher energy data of the LHC.Comment: 13 pages, 3 figures. Corrections in the text and reference
A note on the cylindrical collapse of counter-rotating dust
We find analytical solutions describing the collapse of an infinitely long
cylindrical shell of counter-rotating dust. We show that--for the classes of
solutions discussed herein--from regular initial data a curvature singularity
inevitably develops, and no apparent horizons form, thus in accord with the
spirit of the hoop conjecture.Comment: 8 pages, LaTeX, ijmpd macros (included), 1 eps figure; accepted for
publication in Int. J. Mod. Phys.
Introduction: Narrative in psychotherapy: The emerging metaphor
There has been an increased interest in the study of language processes in psychotherapy. More recently, research and theoretical formulations of the therapeutic process suggested that we must move from the microscopic study of verbal modes to a macroscopic approach in which these modes are organized into narratives. Narratives are conceived, in this perspective, as the basic instruments for meaning making. In this article the research on narrative processes in psychotherapy is reviewed and discussed in terms of its implications for the theory and practice of cognitive narrative psychotherapy. Additionally some of the main data coming from research projects on cognitive narrative psychotherapy are presented
Identificação de CNVs em bovinos Canchim, a partir de dados de gentipagem de SNPs com chips de alta densidade.
O objetivo desse estudo foi utilizar uma ferramenta open source, o CNstream (ALONSO et al., 2010), para a identificação de CNVs a partir de dados de genotipagem de bovinos por meio de chips de SNPs da plataforma Illumina. Foram utilizados dados de 400 animais (bovinos Canchim), participantes de um programa de melhoramento da Embrapa Pecuária Sudeste, genotipados com o BovineHD BeadChip (Illumina)
AN EXERGY COST ANALYSIS OF A COGENERATION PLANT
The exergy analysis, including the calculation of the unit exergetic cost of all flows of the cogeneration plant, was the main purpose of the thermoeconomic analysis of the STAG (STeam And Gas) combined cycle CHP (Combined Heat and Power) plant. The combined cycle cogeneration plant is composed of a GE10 gas turbine (11250 kW) coupled with a HRSG (Heat Recovery Steam Generator) and a condensing extraction steam turbine. The GateCycleTM Software was used for the modeling and simulation of the combined cycle CHP plant thermal scheme, and calculation of the thermodynamic properties of each flow (Mass Flow, Pressure, Temperature, Enthalpy). The entropy values for water and steam were obtained from the Steam Tab software while the entropy and exergy of the exhaust gases were calculated as instructed by. For the calculation of the unit exergetic cost was used the neguentropy and Structural Theory of Thermoeconomic. The GateCycleTM calculations results were exported to an Excel sheet to carry out the exergy analysis and the unit exergetic cost calculations with the thermoeconomic model that was created for matrix inversion solution. Several simulations were performed varying separately five important parameters: the Steam turbine exhaust pressure, the evaporator pinch point temperature, the steam turbine inlet temperature, Rankine cycle operating pressure and the stack gas temperature to determine their impact in the recovery cycle heat exchangers transfer area, power generation and unit exergetic cost
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