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X. Jiang G.A. Navarro R. Sassot 《The European Physical Journal C - Particles and Fields》2006,47(1):81-85
We investigate the potential impact of forthcoming Jefferson Lab semi-inclusive polarized deep inelastic scattering proton
measurements in the determination of the sea quark polarization in the nucleons by means of a next to leading order global
QCD analysis. Specifically, we estimate the resulting improvement in the constraints on polarized parton densities for different
flavors, which is found to be significant for up and strange quarks, and the correlation between remaining uncertainty ranges
for each of the parton species.
PACS 12.38.Bx, 13.85.Ni 相似文献
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Epele L. N. Fanchiotti H. García Canal C. A. Leader E. Sassot R. 《Zeitschrift fur Physik C Particles and Fields》1994,61(2):285-291
The thermodynamic potential (TDP) of the boson sector of the Weinberg-Salam model in an external uniform magnetic field at finite temperature and nonzero chemical potential is calculated in one-loop approximation. In the high temperature limit with the use of Mellin summation technique explicit expressions for the thermodynamic potential are obtained to analyze its new minimum, different from the ordinary Higgs one. This new minimum is due to the root singularity in the oneloop expression for the TDP, originating as a consequence of the tachyonic mode in the spectrum of gauge boson in the magnetic field. It is demonstrated that in the high temperature limit the Higgs minimum possesses properties common with the ordinary superconductors and Abelian Higgs model. The influence of the magnetic field on the Higgs minimum is indirect and has a sufficiently complicated character. The presence of the non-zero chemical potential lowers the critical temperature leading to the disappearance of the Higgs minimum. 相似文献
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We perform a detailed study of the consistency between different sets of polarized deep inelastic scattering data and theory,
from the standpoint of a next to leading order QCD global analysis, and following the criteria proposed by Collins and Pumplin.
In face of recent suggestions that challenge the usual assumption about parent parton spin independence of unpolarized fragmentation
functions, we specially focus on polarized semi-inclusive data.
Received: 2 December 2002 / Revised version: 6 February 2003 / Published online: 31 March 2003
RID="a"
ID="a" e-mail: sassot@df.uba.ar * Partially supported by Conicet and Fundación Antorchas 相似文献
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D. de Florian C. García Canal R. Sassot 《Zeitschrift fur Physik C Particles and Fields》1997,75(2):265-270
We compute the ratio between the direct and the resolved photon components of single jet and dijet production in ep collisions for the kinematical range covered by the most recent ZEUS data. We analyse the phenomenological consequences of different models for the structure of virtual photons in these observables and compare them with the available data. We also comment on the correlation between the so-called $x_{αmma}^{? obs}$ and the ‘true’ xγ, that can be inferred from the data. 相似文献
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We present a new analysis of the helicity parton distributions of the nucleon. The analysis takes into account the available data from inclusive and semi-inclusive polarized deep inelastic scattering, as well as from polarized proton-proton (p-p) scattering at RHIC. For the first time, all theoretical calculations are performed fully at next-to-leading order (NLO) of perturbative QCD, using a method that allows incorporation of the NLO corrections in a very fast and efficient way in the analysis. We find evidence for a rather small gluon polarization in the nucleon, over a limited region of momentum fraction, and for interesting flavor patterns in the polarized sea. 相似文献
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D. de Florian L. N. Epele H. Fanchiotti C. A. García Canal R. Sassot 《Zeitschrift für Physik A Hadrons and Nuclei》1994,350(1):55-59
Recent data on Drell-Yan processes induced by protons on nuclear targets gives non trivial information about nuclear effects. A very simple model for excess pions in nuclei reproduces the main features of these data, and also of those comming from deep inelastic experiments. This simple scheme gives an unified treatement of nuclear effects highlighting its importance in the deuteron and provides a precise prediction for futurep-p andp-d Drell-Yan experiments. 相似文献
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