Dissociated coloured quarks and inclusive scattering

Nuclear Physics A, 1999

Multiple interactions of quarks and gluons in high-energy heavy-ion collisions may give rise to interesting phemomena of color charges propagating in high-density QCD matter. We study the dynamics of multi-parton systems produced in nucleus-nucleus collisions at energies corresponding the the CERN SPS and the future BNL RHIC experiments. Due to the complexity of the multi-particle dynamics we c hoose to employ the parton cascade model in order to simulate the development o f m ultiple parton scatterings and associated stimulated emision processes. Our results indicate a nonlinear increase with nuclear mass A of, e.g., parton multiplicity, energy density, strangeness, and contrasts a linear A-scaling as in Glauber-type approaches. If multiple interactions are suppressed and only single parton scatterings (no re-interactions) are considered, we recover such a linear behavior. It remains to be studied whether these results on the parton level can be experimentally seen in nal-state observables, such as the charged particle multiplicity, the magnitude of produced transverse energy, or the number of produced strange hadrons.

Nuclear Physics A, 1987

pp annihilation into mesons in flight and at rest are analysed in the constituent quark model with the 'P, and the 'S, model for the qq pair creation/annihilation vertex. In the 3P, model, one assumes that the created/annihilated qS pair has the quantum number of the vacuum, while in the 'S, model, it has the quantum number of a gluon. As the meson channels we consider combinations of s-wave mesons and p-wave mesons, and in the annihilation into two mesons we compare the annihilation model (A2), the rearrangement model with a 'P,, vertex (R2) and the rearrangement with a 'S, vertex (S2). The initial state interaction is taken into account by solving the coupled Lippmann-Schwinger equation including virtual Nd+ RA and Ad channels. The combination of R3 and A2 in the 'P,, model roughly reproduces the branching ratios of pp annihilation into mesons, while the combination of R3 and R2 and the combination of R3 and S2 show worse agreement with the experimental branching ratios. The total pp annihilation cross section turned out to be about 60% of the experimental value for R3 + A2 and R3 + R2 and about 70% for R3 + S2, which means that we need other mechanisms of pp annihilation into mesons. The channel of virtual 3's modifies the branching ratios of certain partial waves, but in the total annihilation cross section, the effect of A's is not large.

arXiv (Cornell University), 2003

In a scenario where the constituent quarks are composite systems, Generalized Parton Distributions (GPDs) are built from wave functions to be evaluated in a Constituent Quark Model (CQM), convoluted with the GPDs of the constituent quarks themselves. The approach permits to access the full kinematical range corresponding to the DGLAP and ERBL regions, so that cross sections for deeply virtual Compton scattering can be estimated.

Physical Review D, 2003

Nuclear Physics A, 2005

0375-9474/$ -see front matter

Physical Review C, 2009

SU (Nc) colour-singlet restriction, along with flavour and spin symmetry, on thermal partonic ensemble is shown to recombine the partons with internal colour structure into colour-singlet multiquark clusters which can be identified with various hadronic modes at a given temperature. This can provide a possible basis for recombination model for hadronization of quark-gluon plasma. This also leads to a natural explanation for the ratio of (anti)protons to pions and the quark number scaling of the elliptic flow coefficient in relativistic heavy-ion collisions.

Physical Review D, 1997

A flavor-universal extension of the strong interactions was recently proposed in response to the apparent excess of high-E T jets in the inclusive jet spectrum measured at the Tevatron. This paper studies the color octet of massive gauge bosons ('colorons') that is present in the low-energy spectrum of the model's Higgs phase. Constraints from searches for new particles decaying to dijets and from measurements of the weak-interaction ρ parameter imply that the colorons must have masses greater than 870-1000 GeV. The implications of recent Tevatron data and the prospective input from future experiments are also discussed.

Journal of Physics: Conference Series, 2018

Double parton distribution functions (dPDFs) represent a tool to explore the 3D partonic structure of the proton. They can be measured in high energy proton-proton and proton nucleus collisions and encode information on how partons inside a proton are correlated among each other. dPFDs are studied here in the valence region by means of a constituent quark model scenario within the relativistic Light Front approach, where two particle correlations are present without any additional prescription. Furthermore, a study of the QCD evolution at high energy scale, of the model results, has been completed in order to compare our predictions with future data analyses. In closing, results on the evaluation of the so called σ ef f , crucial ingredient for the description of double parton scattering, where dPDFs can be accessed, are presented and discussed.

Physics Letters B, 2016

We present a calculation of the effective cross section σ ef f , an important ingredient in the description of double parton scattering in proton-proton collisions. Our theoretical approach makes use of a Light-Front quark model as framework to calculate the double parton distribution functions at low-resolution scale. QCD evolution is implemented to reach the experimental scale. The obtained σ ef f , when averaged over the longitudinal momentum fractions of the interacting partons, x i , is consistent with the present experimental scenario. However the result of the complete calculation shows a dependence of σ ef f on x i , a feature not easily seen in the available data, probably because of their low accuracy. Measurements of σ ef f in restricted x i regions are addressed to obtain indications on double parton correlations, a novel and interesting aspect of the three dimensional structure of the nucleon.

Progress of Theoretical Physics, 1983

Small py inclusive spectra are studied from a constituent quark parton model. The Constituent Quark (CQ) is regarded as made of a valence quark and a cloud of quark-antiquark pairs and gluons. The distribution functions of CQ are estimated using a similar version to the Kuti-Weisskopf model.