Statistical description of the proton spin with a large gluon helicity distribution

The quantum statistical parton distributions approach proposed more than one decade ago is revisited by considering a larger set of recent and accurate Deep Inelastic Scattering (DIS) experimental results. It enables us to improve the description of the data by means of a new determination of the parton distributions. We will see that a large gluon polarization emerges, giving a significant contribution to the proton spin.Comment: 11 pages, 4 figure

New Statistical PDFs: Predictions and Tests up to LHC Energies

The quantum statistical parton distributions approach proposed more than one decade ago is revisited by considering a larger set of recent and accurate Deep Inelastic Scattering experimental results. It enables us to improve the description of the data by means of a new determination of the parton distributions. This global next-to-leading order QCD analysis leads to a good description of several structure functions, involving unpolarized parton distributions and helicity distributions, in a broad range of $x$ and $Q^2$ and in terms of a rather small number of free parameters. There are several challenging issues, in particular the behavior of $\bar d(x) / \bar u(x)$ at large $x$, a possible large positive gluon helicity distribution, etc.. The predictions of this theoretical approach will be tested for single-jet production and charge asymmetry in $W^{\pm}$ production in $\bar p p$ and $p p$ collisions up to LHC energies, using recent data and also for forthcoming experimental results.Comment: 4 pages, 3 figures, Invited talk at Diffraction 2016, Acireale, Sicily (Italy), Sept. 2 - 8 (2016), to be published in the AIP Conference Proceedings. arXiv admin note: substantial text overlap with arXiv:1510.0618

Inversion of initial dominance relationships following the interchange of roles of resident and intruder within pairs of male swordtail fish (Xiphophorus helleri)

This experiment consisted of 75 different pairs composed of two male adults Xiphophorus helleri meeting each other twice. On the first occasion, one of the fish was familiarized with the meeting place for 3h (resident) while its opponent was familiarized with another aquarium (intruder). Upon dominance of one individual over the other, the pair members were separated and returned to their respective home groups for 168 hours (7 days). After this period of separation, the same pair members were reunited and met while roles had been reversed: the initial resident became the intruder, and the initial intruder was given prior-residency. Individuals in the initial resident role defeated the initial intruder in a significant majority of cases (76%). On their second meeting, the newly established dominance relationship was noted in favour of the new resident in a significant majority of cases (82%), and in a reversed direction as compared to the initially established dominance order. This shows that prior-residence is a powerful determinant of dyadic dominance outcome in Xiphophorus males when fish show minimal size differences

The statistical model for parton distributions

The phenomenological motivations, the expressions and the comparison with experiment of the parton distributions inspired by the quantum statistics are described. The Fermi-Dirac expressions for the quarks and their antiparticles automatically account for the correlation between the shape and the first moments of the valence partons, as well as the flavor and spin asymmetries of the sea. One is able to describe with a small number of parameters both unpolarized and polarized structure functions.Comment: 7 pages, 3 figures, Invited talk at XX International Workshop on "`Deep-Inelastic Scattering and related subjects"', University of Bonn, Germany, March 26-30 2012, presented by F. Buccella, to appear in the conference proceeding

How large is the gluon polarization in the statistical parton distributions approach?

We review the theoretical foundations of the quantum statistical approach to parton distributions and we show that by using some recent experimental results from Deep Inelastic Scattering, we are able to improve the description of the data by means of a new determination of the parton distributions. We will see that a large gluon polarization emerges, giving a significant contribution to the proton spin.Comment: 4 pages, 3 figures, Invited talk presented by Jacques Soffer at " DIFFRACTION 2014 ",May 10 - 15, 2014, Primosten (Croatia) (to be published in the AIP Conference Proceedings{\deg

Conflict outcome in male green swordtail fish dyads (Xiphophorus helleri): Interaction of body size, prior dominance/subordination experience and prior residency

The relative contribution of asymmetries in prior experience, size, and prior residency to the determination of dyadic dominance between unacquainted individuals was examined using pairs of green swordtail fish, Xiphophorus helleri. Four types of encounters were staged between an intruder and a smaller resident: (1) both had experienced prior victory; (2) both had experienced prior defeat; (3) the intruder had experienced prior victory and the resident prior defeat; and (4) the intruder had experienced prior defeat and the resident prior victory. In a fifth condition in which two intruders met, one was a prior subordinate and the other a prior dominant smaller in size than its opponent. In all these encounters, the superiority in lateral surface of one fish varied between 0 to 30% over that of its opponent. Results showed that (1) when size differences between contestants were within the range of 0-10% and there was an asymmetry in prior social experience, conflicts were essentially resolved according to prior experience with prior winners systematically defeating prior losers; (2) prior residency of 3 hours was an advantage only when both opponents had experienced prior defeat before meeting and when size asymmetries were small (e.g. <20%). It was not an advantage between prior winners or between a prior winner and a prior loser; (3) when large size asymmetries existed (e.g. 20-30%), size uniquely determined dominance outcome and nullified other advantages or disadvantages due to prior social experience and prior residency; and (4) at intermediate levels of size asymmetries (e.g. 10-20%), size partially cancelled any advantage due to a prior victory, and gradually beacme the most important factor in accounting for victories