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V. Barone

Publications and source records attributed to V. Barone.

36 records · Page 2Linked to original sources
arXiv2001

Non-Standard Time Reversal for Particle Multiplets and the Spin-Flavor Structure of Hadrons

We show that a system of quarks interacting with chiral fields provides a physical representation of a ``non-standard'' time reversal for particle multiplets proposed by Weinberg. As an application, we argue that, if the internal structure of hadrons is described by a chiral lagrangian, the so-called time-reversal-odd quark distribution functions might not be forbidden by time-reversal invariance.

hep-ph↗
arXiv2000

A new global analysis of DIS data and the strange sea distribution

We present the results of a new global analysis of DIS data characterized by an enlarged neutrino and antineutrino data set. Special emphasis is given to the strange sector. The strange sea distribution is determined independently of the non strange sea. The possibility of a charge asymmetry, s(x) different from sbar(x), is tested.

hep-ph↗
arXiv1999

A new global analysis of deep inelastic scattering data

A new QCD analysis of Deep Inelastic Scattering (DIS) data is presented. All available neutrino and anti-neutrino cross sections are reanalysed and included in the fit, along with charged-lepton DIS and Drell-Yan data. A massive factorisation scheme is used to describe the charm component of the structure functions. Next-to-leading order parton distribution functions are provided. In particular, the strange sea density is determined with a higher accuracy with respect to other global fits.

hep-ph↗
arXiv1998

Gluon Spin in a Quark Model

We compute the gluon polarization $ΔG$ and the gluon total angular momentum $J_g$ in the Isgur-Karl quark model. Taking into account self-interaction contributions, we obtain for both quantities a positive value of about 0.24 at the model scale $μ_0^2 \simeq 0.25$ GeV$^2$. This estimate is reasonably close to the expectation from polarized deep inelastic scattering analyses.

hep-ph↗
arXiv1997

On the low x behaviour of nuclear shadowing

We calculate the x dependence of nuclear shadowing at moderate values of Q^2 by using HERA diffractive data and, for consistency, F2 parameterization of ZEUS. We show that no decrease of shadowing occurs down to very low x (x = 10^-4).

hep-ph↗
arXiv1997

Double-Spin Transverse Asymmetries in Drell-Yan Processes

We calculate the double-spin transverse asymmetries for the Drell-Yan lepton pair production in p-p and p-anti p collisions. We assume the transverse and the longitudinal polarization densities to be equal at a very small scale, as it is suggested by confinement model results. Using a global fit for the longitudinal distributions, we find transverse asymmetries of order of 10^-2 at most, in the accessible kinematic regions.

hep-ph↗
arXiv1996

Longitudinal and Transverse Nuclear Shadowing

Nuclear shadowing arises from multiple scattering of the hadronic fluctuations of the virtual photon in a nucleus. We predict different longitudinal and transverse shadowing and an A-dependence of R which can be up to a 50% effect. The possibility of detecting nuclear effects on R at HERA is discussed.

hep-ph↗
arXiv1996

A confinement model calculation of h_1(x)

The transverse polarization distribution of quarks $h_1(x)$ is computed in a confinement model, the chiral chromodielectric model. The flavor structure of $h_1$, its $Q^2$ evolution and Soffer's inequality are studied. The Drell--Yan double transverse asymmetry $A_{TT}$ is evaluated and found to be one order of magnitude smaller than the double longitudinal asymmetry.

hep-ph↗
arXiv1995

Extracting the Strange Density from $xF_3$

We present a QCD analysis of the strange and charm contributions to the neutrino deep inelastic structure function $xF_3$. We show that next-to-leading order effects, which are relatively important for $F_2$, play a lesser role in the case of $xF_3$. The neutrino--antineutrino difference $xF_3^ν - xF_3^{\bar ν}$ provides a new determination of the strange density, which exhibits some advantages with respect to other traditional methods.

hep-ph↗
arXiv1995

The Strange Quark Distribution

We discuss the latest CCFR determination of the strange sea density of the proton. We comment on the differences with a previous, leading--order, result and point out the relevance of quark mass effects and current non--conservation effects. By taking them into account it is possible to solve the residual discrepancy with another determination of the strange quark distribution. Two important sources of uncertainties are also analyzed.

hep-ph↗
arXiv1994

Anomalous Evolution of Nonsinglet Nucleon Structure Functions

We calculate the scale dependence of nonsinglet nucleon structure functions. Due to anomalous axial symmetry breaking a large flavour asymmetry of the quark--antiquark sea is generated nonperturbatively. This produces a strong scale dependence of the nonsinglet structure function in an intermediate range of $Q^2$. Evolving nonperturbatively a pure valence distribution from an infrared scale we can thus compute $F_2^p-F_2^n$ as measured by the NMC, and give detailed predictions for its $Q^2$ dependence at fixed $x$. We also compare our results with Drell--Yan data.

hep-ph↗
arXiv1994

Leptoproduction of charm revisited

We calculate the energy--momentum distribution of the charmed quarks produced in neutrino reactions on protons, quantifying the importance of mass and current non--conservation effects. We study the strange and charm distributions probed in neutrino interactions in the presently accessible kinematical region. Some ambiguities inherent to the extraction of the parton densities from dimuon data are pointed out.

hep-ph↗
arXiv1993

Shadowing in deuterium and the small--$x$ limit of $F_2^n/F_2^p$ and $F_2^p - F_2^n$

We discuss the updated NMC determination of $F_2^n/F_2^p$ and $F_2^p - F_2^n$. Shadowing effects in deuterium make the structure functions determined by the NMC sensibly different from the true ones in the low--$x$ region. We show that the departure of $F_2^n/F_2^p$ and $F_2^p-F_2^n$ from the Regge expectations at small $x$ observed by the NMC likely disappears if one takes into account the shadowing corrections.

hep-ph↗
arXiv1993

Non universality of structure functions and measurement of the strange sea density

We show that there is no real conflict between the two determinations of the strange sea density from the opposite--sign dimuon production and from the difference of the $F_2$ structure functions measured in neutrino and muon deep inelastic scattering. Once non universal sea parton densities are introduced, which take into account the effects of different mass thresholds and different longitudinal contributions, the discrepancy is shown to disappear and both sets of data are simultaneously well reproduced. No need for a large strange sea content of the nucleon emerges.

hep-ph↗
arXiv1993

Unitarization of Structure Functions at Large ${\bf 1/x}$

We discuss the effects of the $s$-channel unitarization on the $x$ and $Q^{2}$ dependence of structure functions. The unitarization is implemented at the level of photoabsorption cross sections by resorting to the light--cone wave functions of virtual photons and to the diagonalization property of the scattering matrix in a basis of Fock states of the photon with fixed transverse size. Triple pomeron effects are also explicitly taken into account. We find large unitarity corrections to the structure functions at $x < 10^{-2}$. The results are in very good agreement with the existing NMC and the preliminary HERA data.

hep-ph↗