The statistical parton distributions: status and prospects

New experimental results on polarized structure functions, cross sections for $e^{\pm}p$ neutral and charge current reactions and $\nu$ ($\bar{\nu}$) charge current on isoscalar targets are compared with predictions using the statistical parton distributions, which were previously determined. New data on cross sections for Drell-Yan processes, single jet in $p\bar{p}$ collisions and inclusive $\pi^0$ production in $pp$ collisions are also compared with predictions from this theoretical approach. The good agreement which we find with all these tests against experiment, strenghtens our opinion on the relevance of the role of quantum statistics for parton distributions. We will also discuss the prospects of this physical framework.Comment: 34 pages, 23 figures, references and figures adde

The strangeness content of the nucleon

We evaluate the matrix element of $\bar{q} q$ in hadron states on a lattice. We find substantial mixing of the connected and disconnected contributions so that the lattice result that the disconnected contribution to the nucleon is large does not imply that the $\bar{s} s$ content is large. This has implications for dark matter searches.Comment: contribution to Lattice2001(matrixelement

LHC Coverage of RPV MSSM with Light Stops

We examine the sensitivity of recent LHC searches to signatures of supersymmetry with R-parity violation (RPV). Motivated by naturalness of the Higgs potential, which would favor light third-generation squarks, and the stringent LHC bounds on spectra in which the gluino or first and second generation squarks are light, we focus on scenarios dominated by the pair production of light stops. We consider the various possible direct and cascade decays of the stop that involve the trilinear RPV operators. We find that in many cases, the existing searches exclude stops in the natural mass range and beyond. However, typically there is little or no sensitivity to cases dominated by UDD operators or LQD operators involving taus. We propose several ideas for searches which could address the existing gaps in experimental coverage of these signals.Comment: 41 pages, 12 figures; v2: included new searches (see footnote 10), minor corrections and improvement

Novel Bose-Einstein Interference in the Passage of a Fast Particle in a Dense Medium

When an energetic particle collides coherently with many medium particles at high energies, the Bose-Einstein symmetry with respect to the interchange of the exchanged virtual bosons leads to a destructive interference of the Feynman amplitudes in most regions of the phase space but a constructive interference in some other regions of the phase space. As a consequence, the recoiling medium particles have a tendency to come out collectively along the direction of the incident fast particle, each carrying a substantial fraction of the incident longitudinal momentum. Such an interference appearing as collective recoils of scatterers along the incident particle direction may have been observed in angular correlations of hadrons associated with a high-$p_T$ trigger in high-energy AuAu collisions at RHIC.Comment: 10 pages, 2 figures, invited talk presented at the 35th Symposium on Nuclear Physics, Cocoyoc, Mexico, January 3, 2012, to be published in IOP Conference Serie

Structure functions at large x

Structure function data together with other measurements from fixed-target deep inelastic scattering and hadron-hadron collider experiments which contribute to our knowledge of the parton density functions are reviewed. The inclusive cross-section measurements of neutral and charged current interactions at HERA are presented and their impact on the parton density functions is discussed. Future prospects for an improved knowledge of the parton density functions at large x are briefly mentioned.Comment: Invited talk given at the workshop on ``New Trends in HERA Physics 2001'', Ringberg castle, Germany, June 17-22, 200

Light hadrons in 2+1 flavor lattice QCD

This talk will focus on recent results by the MILC collaboration from simulations of light hadrons in 2+1 flavor lattice QCD. We have achieved high precision results in the pseudoscalar sector, including masses and decay constants, plus quark masses and Gasser-Leutwyler parameters from well controlled chiral perturbation theory fits to our data. We also show spectroscopy results for vector mesons and baryons.Comment: To appear in the proceedings of the First Meeting of the APS Topical Group on Hadronic Physics, Fermilab, Batavia, Illinois, Oct. 24-26, 200

The mass of the charm quark from unquenched lattice QCD at fixed lattice spacing

We determine the mass of the charm quark ($m_c$) from lattice QCD with two flavors of dynamical quarks with a mass around the strange quark. We compare this to a determination in quenched QCD which has the same lattice spacing (0.1 fm). We investigate different formulations of the quark mass, based on the Vector Ward Identity, PCAC relation and the FNAL heavy quark formalism. Based on these preliminary results we find no effects due to sea quarks with a mass around strange.Comment: Presented at 21st International Symposium on Lattice Field Theory (LATTICE 2003), Tsukuba, Japan, 15-19 July, 200