Studies of backward particle production with A Fixed-Target Experiment using the LHC beams

The foreseen capability to cover the far backward region at A Fixed-Target Experiment using the LHC beams allows to explore the dynamics of target fragmentation in hadronic collisions. In this report we briefly outline the required theoretical framework and discuss a number of studies of forward and backward particle production. By comparing this knowledge with the one accumulated in Deep Inelastic Scattering on target fragmentation, the basic concept of QCD factorisation could be investigated in detail.Comment: Contribution to the special issue on "A Fixed-Target Experiment using the LHC beams". Phenomenological section describing single hard diffraction added. 8 plots adde

Transverse momentum distributions in Semi-inclusive Deep Inelastic Scattering

Within a perturbative approach to Quantum Chromodynamics (QCD), we show how to extend ordinary DGLAP longitudinal evolution equations to include the radiative transverse momentum generated in the collinear branching regime. Considering Semi-inclusive Deep Inelastic Scattering as a reference process, we perform such a generalization both in the current and in the target fragmentation region. These distributions are then used to predict semi-inclusive Deep Inelastic Scattering cross-sections onto the whole phase space of the detected hadron.Comment: 6 pages. Invited talk at "Symmetries and Spin", Prague, July 19-2

Scale evolution of kt-distributions

We review some of the features of the evolutions equations for transverse momentum dependent parton distributions recently proposed by us. We briefly describe the new ingredients entering the equations and their relationship with ordinary evolution equations. We comment on possible choices for the initial conditions and then show results for the evolved distributions obtained by numerical implementation of the equations. By computing the average transverse momentum at different scale we highlight some general properties of the solutions.Comment: Contribution to the XVIII International Workshop on Deep-Inelastic Scattering and Related Subjects, April 19 -23, 2010, Florence, Italy. 5 pages, 2 figure

QCD analysis of forward neutron production in DIS

We consider forward neutron production in DIS within fracture functions formalism. By performing a QCD analysis of available data we extract proton-to-neutron fracture functions exploiting a method which is in close relation with the factorisation theorem for this class of processes.Comment: 18 pages, 5 figures, revtex

A second update on double parton distributions

We present two equivalent consistency checks of the momentum sum rule for double parton distributions and show the importance of the inclusion of the so-called inhomogeneous term in order to preserve correct longitudinal momentum correlations. We further discuss in some detail the kinematics of the splitting at the basis of the inhomogeneous term and update the double parton distributions evolution equations at different virtualities.Comment: Two reference added. Additional appendix. Minor changes on the tex

Single-diffractive Drell-Yan pair production at the LHC

We present predictions for single-diffractive low-mass Drell-Yan pair production in $pp$ collisions at the LHC at $\sqrt{s}=13$ TeV. Predictions are obtained adopting a factorised form for the relevant cross sections and are based on a new set of diffractive parton distributions resulting from the QCD analysis of combined HERA leading proton data. We discuss a number of observables useful to characterise the expected factorisation breaking effects.Comment: 22 pages, 2 tables, 9 figures. Typos corrected, 3 References adde

QCD analysis of Lambda hyperon production in DIS target-fragmentation region

We consider Lambda-hyperon production in the target-fragmentation region of semi-inclusive deep-inelastic scattering within the framework of fracture functions. We present a first attempt to determine the flavour and energy dependences of these non-perturbative distributions through a simultaneous QCD-based fit to available neutral- and charged-current semi-inclusive-DIS cross sections. Predictions based on the resulting nucleon-to-Lambda fracture functions are in good agreement with data and observables not included in the regression. The successful prediction of the $Q^2$ dependence of the Lambda multiplicity notably represents the first validation of the perturbative framework implied by fracture functions.Comment: Detailed comparison to quark-gluon string model added together with 3 additional plots. Three references added. Conclusions unchanged. Minor corrections to the text. 18 pages, 18 figures, 3 table

Lambda production in the DIS target fragmentation region

By using a recently obtained set of Lambda fracture functions, we present predictions for Lambda production in the target fragmentation region of Semi-Inclusive Deep Inelastic Scattering in CLAS@12 GeV kinematics, supplemented with a conservative error estimates. We discuss a number of observables sensitive to the assumptions of the underlying theory and many of the assumptions of the proposed phenomenological model.Comment: 16 pages, 11 figures, updated experimental and theoretical errors estimation. Accepted for publication in EPJ

Hadronic structure from double parton scattering

In the present paper we consider the so-called effective cross section, a quantity which encodes the experimental knowledge on double parton scattering in hadronic collisions that has been accomulated so far. We show that the effective cross section, under some assumptions close to those adopted in its experimental extractions, can be used to obtain a range of mean transverse distance between an interacting parton pair in double parton scattering. Therefore we have proved that the effective cross section offers a way to access information on the hadronic structure.Comment: 5 pages, 1 figure. References added and figure updated. Referee suggestions implemented. Published in PRD rapid communicatio

On the QCD Evolution of Transverse Momentum Dependent Distributions

We reconsider the evolution equations for transverse momentum dependent distributions recently proposed by us and recast them in a form which allows the comparison with results recently appeared in the literature. We show under which conditions the obtained results might be consistent with each other.Comment: 13 pages, no figures, minor changes to text, one reference adde