arXiv subjects

D. Treleani

Publications and source records attributed to D. Treleani.

At least 37 records · Page 2Linked to original sources

arXiv2002

On the jet spectrum in nucleus-nucleus interactions

We derive the inclusive transverse spectrum of minijets in nuclear collisions at very high energies by assuming that the nuclear S-matrix factorizes into a product of elastic S-matrices for elementary partonic collisions. Interference effects and, in particular, the contribution of loop diagrams are fully taken into account in the derivation of the spectrum, which is shown to coincide with the result earlier obtained by superposing the elementary interactions incoherently. A quantitative analysis confirms that the deformation induced by multiple collsions is a large effect at RHIC and LHC energies, for transverse momenta ~ 20 GeV.

hep-ph↗

arXiv2001

Measuring Double Parton Distributions in Nucleons at Proton-Nucleus Colliders

We predict a strong enhancement of multijet production in proton-nucleus collisions at collider energies, as compared to a naive expectation of a cross section $\propto A$. The study of the process would allow to measure, for the first time, the double parton distribution functions in a nucleon in a model independent way and hence to study both the longitudinal and the transverse correlations of partons.

hep-ph↗

arXiv2001

Finite formation time effects in inclusive and semi-inclusive electro-disintegration of few-body nuclei

Finite Formation Time (FFT) effects in the exclusive reaction ^4He(e,e'p)^3H at high values of Q^2 are introduced and discussed. It is shown that the minimum in the momentum distributions predicted by the Plane Wave Impulse Approximation (PWIA), which is filled by the Glauber-type Final State Interaction (FSI), is completely recovered when FFT effects are taken into account. The semi-inclusive process ^4 He(e,e'p)X is also investigated.

nucl-th↗

arXiv2001

Minijet transverse spectrum in high-energy hadron-nucleus collisions

Hadron-nucleus collisions at LHC energies are studied by including explicitly semi-hard parton rescatterings in the collision dynamics. Under rather general conditions, we obtain explicit formulae for the semi-hard cross-section and the inclusive minijet transverse spectrum. As an effect of the rescatterings the spectrum is lowered at small $p_t$ and is enhanced at relatively large transverse momenta, the deformation being more pronounced at increasing rapidity. Its study allows to test the proposed interaction mechanisms and represents an important baseline to examine nucleus-nucleus collisions.

hep-ph↗

arXiv2001

Hard Parton Rescatterings and Minijets in Nuclear Collisions at LHC

The average number of minijets and the corresponding transverse energy produced in heavy ion collisions are evaluated by including explicitly semi-hard parton rescatterings in the dynamics of the interaction. At the LHC semi-hard rescatterings have a sizable effect on global characteristics of the typical inelastic event. An interesting feature is that the dependence on the cutoff which separates soft and hard parton interactions becomes less critical after taking rescatterings into account.

hep-ph↗

arXiv2000

Final state interaction in inclusive and exclusive quasi-elastic processes

We discuss a new approach to final state interactions, that keeps explicitly into account the virtuality of the ejected nucleon in quasi-elastic $A(e,e'p)X$ scattering at very large $Q^2$, and we present some recent results, at moderately large $Q^2$ values, for the nuclear transparency in $^4He$, $^{16}O$ and $^{40}Ca$ and for the momentum distributions of $^4He$.

nucl-th↗

arXiv2000

Scale Factor in Double Parton Collisions and Parton Densities in Transverse Space

The scale factor $σ_{eff}$, which characterizes double parton collisions in high energy hadron interactions, is a direct manifestation of the distribution of the interacting partons in transverse space, in such a way that different distributions give rise to different values of $σ_{eff}$ in different double parton collision processes. We work out the value of the scale factor in a few reactions of interest, in a correlated model of the multi-parton density of the proton recently proposed.

hep-ph↗

arXiv2000

On the effects of the final state interaction in the electro-disintegration of the deuteron at intermediate and high energies

The role of the final state interactions (FSI) in the inclusive quasi-elastic disintegration of the deuteron is investigated treating the two-nucleon final state within the exact continuum solutions of the non-relativistic Schroedinger equation, as well as within the Glauber multiple scattering approach. It is shown that for values of the Bjorken scaling variable $x_{Bj}\simeq 1$ both approaches provide similar results, unless the case $x_{Bj}\gtrsim 1$, where they appreciably disagree. It is demonstrated that present experimental data, which are mostly limited to a region of four-momentum transfer ($Q^2 \lesssim 4 (GeV/c)^2$) where the Center-of-Mass energy of the final state is below the pion threshold production, can be satisfactorily reproduced by the approach based on the exact solution of the Schroedinger equation and not by the Glauber approach. It is also pointed out that the latter, unlike the former, does not satisfy the inelastic Coulomb sum rule, the violation being of the order of about 20%.

nucl-th↗

arXiv2000

QCD

We discuss issues of QCD at the LHC including parton distributions, Monte Carlo event generators, the available next-to-leading order calculations, resummation, photon production, small x physics, double parton scattering, and backgrounds to Higgs production.

hep-ph↗

arXiv1999

A double parton scattering background to Higgs boson production at the LHC

The experimental capability of recognizing the presence of b quarks in complex hadronic final states has addressed the attention towards final states with b\bar{b} pairs for observing the production of the Higgs boson at the LHC, in the intermediate Higgs mass range.We point out that double parton scattering processes are going to represent a sizeable background to the process.

hep-ph↗

arXiv1999

A realistic study of the nuclear transparency and the distorted momentum distributions in the semi-inclusive process 4He(e,e'p)X

The nuclear transparency and the distorted momentum distributions of 4He in the semi-inclusive process 4He(e,e'p)X are calculated within the Glauber multiple scattering approach using for the first time realistic four-body variational wave functions embodying central and non-central nucleon-nucleon (N-N) correlations. The contributions from N-N correlations and from Glauber multiple scattering are taken into account exactly to all orders. It is shown that non-central correlations significantly affect both the transparency and the distorted momentum distributions; as a matter of fact: i) the small (approx 3%) value of the effect of correlations on the transparency results from an appreciable cancellation between the short-range central repulsive correlations and the intermediate-range attractive correlations, whose magnitude is significantly affected by the non-central forces, and ii) the effect of Glauber final state interactions on the momentum distribution is reduced by the inclusion of tensor correlations.

nucl-th↗

arXiv1999

A linked cluster expansion for the calculation of the semi-inclusive A(e,e'p)X processes using correlated Glauber wave functions

The distorted one-body mixed density matrix, which is the basic nuclear quantity appearing in the definition of the cross section for the semi-inclusive A(e,e'p)X processes, is calculated within a linked-cluster expansion based upon correlated wave functions and the Glauber multiple scattering theory to take into account the final state interaction of the ejected nucleon. The nuclear transparency for 16O and 40Ca is calculated using realistic central and non-central correlations and the important role played by the latter is illustrated.

nucl-th↗

arXiv1999

A Hamiltonian Model for Hard Inelastic Hadronic Collisions

Hamiltonian eikonal model for multiple production in high energy hadron-hadron collisions is presented and worked out with the aim of providing a simple frame for various different observables. An important role is played by unitarity which is built in by construction in the Hamiltonian formulation. The eikonal approximation allows both a very effective simplification of the dynamics, and facilitates the discussion on the relevance of possible spatial inhomogeneities of the hadrons. The model is intended to describe only the hard interaction of the constituents, the structure of the incoming hadrons and the final hadronization processes are outside the scope of the present investigation.

hep-ph↗

arXiv1999

Proton Structure in Transverse Space and the Effective Cross Section

The observation of double parton collisions by CDF has provided the first direct information on the structure of the proton in transverse space. The actual quantity which has been measured is the `effective cross section' $σ_{eff}$, which is related to the transverse size of the region where hard interactions are localized. The actual value which has been measured is sizably smaller than naively expected and it is an indication of important correlation effects in the many-body parton distribution of the proton. We discuss the problem pointing out a possible source of correlations in the proton structure, which could have a significant effect on the value of $σ_{eff}$.

hep-ph↗

arXiv1998

Missing momentum distributions and nuclear transparency in semi-inclusive A(e,e'p)X processes

A linked cluster expansion for the distorted one-body mixed density matrix is obtained within the Glauber multiple scattering theory with correlated wave functions. The nuclear transparency for 16O is calculated using realistic central and non-central correlations. The convergence of the expansion is investigated in the case of 4He for which the transparency and the distorted momentum distributions are calculated to all order in the correlations using a variational wave function obtained from realistic NN interactions. The important role played by non central correlations is illustrated.

nucl-th↗

arXiv1998

Rapidity Distributions of Jets Produced in Heavy Ion Collisions at LHC

We discuss the rapidity distribution of produced jets in heavy-ion collisions at LHC. The process allows one to determine to a good accuracy the value of the impact parameter of the nuclear collision in each single inelastic event. The knowledge of the geometry is a powerful tool for a detailed analysis of the process, making it possible to test the various different elements which, in accordance with present theoretical ideas, take part to the production mechanism.

hep-ph↗

arXiv1998

Stripping Cross Sections in Collisions of Light Nuclei

By evaluating all the contributions of the intermediate states of the multiple scattering theory diagrams, we compute the integrated stripping cross sections of collisions among light nuclei. The resulting expressions have the simple form of a combination of total inelastic cross sections of nuclear reactions with projectile nuclei differing in the atomic mass number. We also check the accuracy of some widely used relations in heavy ion collisions.

hep-ph↗

arXiv1997

Double parton scatterings in high energy hadronic collisions

CDF has recently measured a large number of double parton scatterings. The observed value of $σ_{eff}$, the non perturbative parameter which characterizes the process, is considerably smaller as compared with the naive expectation. The small value of $σ_{eff}$ is likely to be an indication of the importance of the two-body parton correlations in the many-body parton distributions of the proton.

hep-ph↗