2,907 research outputs found
Can the "standard" unitarized Regge models describe the TOTEM data?
The standard Regge poles are considered as inputs for two unitarization
methods: eikonal and U-matrix. It is shown that only models with three input
pomerons and two input odderons can describe the high energy data on and
elastic scattering including the new data from Tevatron and LHC.
However, it seems that the both considered models (eikonal and U-matrix)
require a further modification (e.g., to explore nonlinear reggeon trajectories
and/or nonexponential vertex functions) for a more satisfactory description of
the data at 19.0 GeV 7 TeV and 0.01 14.2
GeV.Comment: 11 pages, 7 figures, typos are corrected, minor corrections in the
text, No changes in results and conclusion. To appear in EP
Impact analysis of TOTEM data at the LHC: black disk limit exceeded
We discuss the profile of the impact--parameter dependent elastic scattering
amplitude. Extraction of impact-parameter dependence from the dataset with
inclusion of the experimental data on elastic scattering at the LHC energies
helps to reveal the asymptotics of hadron interactions. Analysis of the data
clearly indicates that the impact-parameter elastic scattering amplitude exceed
the black disk limit at the LHC energy 7TeV and the inelastic overlap function
reaches its maximum value at Comment: 5 pages, 5 figure
On jet structure in heavy ion collisions
The LHC data on jet fragmentation function and jet shapes in PbPb collisions
at center-of-mass energy 2.76 TeV per nucleon pair are analyzed and interpreted
in the frameworks of PYQUEN jet quenching model. A specific modification of
longitudinal and radial jet profiles in most central PbPb collisions as
compared with pp data is close to that obtained with PYQUEN simulations taking
into account wide-angle radiative and collisional partonic energy loss. The
contribution of radiative and collisional loss to the medium-modified intra-jet
structure is estimated.Comment: 9 pages including 3 figures as EPS-files; prepared using LaTeX
package for publication in the European Physical Journal
Choosing an Evaluation Theory: A Supplement to Evaluation Roots (3rd Edition)
Background: Unlike scientific theories, evaluation theories are prescriptive: a set of actions and approaches that should be followed when conducting an evaluation. While evaluation theorists have offered a variety of writings describing their theories and approaches, few have offered a specific outline of what the theory looks like in practice. Thus, Alkin and Christie formulated a book to aid evaluators in how to apply theories in evaluations (Alkin & Christie, forthcoming). This book culminates in a series of prototypes that outline each theory’s goals, appropriate contexts, prescriptions, and observable actions in application.
Purpose: In order to aid evaluators in applying theories, this article seeks to provide a basis for comparison that can be used to help evaluators select which theory would be most appropriate in their practice.
Setting: This comparison can be applied in any setting where evaluations fit the context prescribed by each of the theories.
Intervention: Not applicable.
Research Design: Not applicablre.
Data Collection and Analysis: Not applicable.
Findings: In order for theories to influence practice effectively, theories must be displayed in a way that allows for easy comparison. This comparison of three theory prototypes demonstrates that prototypes can be an effective way for selecting a prescriptive theory when conducting an evaluation.
Keywords: prescriptive theories; practice; empowerment evaluation; learning centered model; developmental evaluatio
Dispersion relations for meson-proton and proton-proton forward elastic scattering
An analysis of the data on forward and
scattering is performed making use of the single- and double-subtraction
integral and comparing with derivative dispersion relations for amplitudes.
Various pomeron and odderon models for the total cross sections are considered
and compared. The real part of the amplitude is calculated via dispersion
relations. It is shown that the integral dispersion relations lead to a better
description of the data for 5 GeV. Predictions of the considered
models for the TOTEM experiment at LHC energies are givenComment: 15 pages, 12 figures. Presented at the workshop "30 years of strong
interactions", Spa, Belgium, 6-8 April 2011. Version published in Few Body
Systems: typos correcte
Forward Physics at the LHC (Elba 2010)
The papers review the main theoretical and experimental aspects of the
Forward Physics at the Large Hadron Collider
Measurement of an excess in the yield of J/ at very low in Pb-Pb collisions at = 2.76 TeV
We report on the first measurement of an excess in the yield of J/ at
very low transverse momentum ( GeV/) in peripheral hadronic
Pb-Pb collisions at = 2.76 TeV, performed by ALICE at the
CERN LHC. Remarkably, the measured nuclear modification factor of J/ in
the rapidity range reaches about 7 (2) in the range 0-0.3
GeV/ in the 70-90% (50-70%) centrality class. The J/ production cross
section associated with the observed excess is obtained under the hypothesis
that coherent photoproduction of J/ is the underlying physics mechanism.
If confirmed, the observation of J/ coherent photoproduction in Pb-Pb
collisions at impact parameters smaller than twice the nuclear radius opens new
theoretical and experimental challenges and opportunities. In particular,
coherent photoproduction accompanying hadronic collisions may provide insight
into the dynamics of photoproduction and nuclear reactions, as well as become a
novel probe of the Quark-Gluon Plasma.Comment: 18 pages, 3 captioned figures, 1 table, authors from page 13,
published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/191
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