Diffractive dissociation in proton-nucleus collisions at collider energies

The cross section for the nuclear diffractive dissociation in proton-lead collisions at the LHC is estimated. Based on the current theoretical uncertainties for the single (target) diffactive cross section in hadron-hadron reactions one obtains sigma_SD(5.02 TeV) = 19.67 \pm 5.41 mb and sigma_SD(8.8 TeV) = 18.76 \pm 5.77 mb, respectively. The invariant mass M_X for the reaction pPb -> pX is also analyzed. Discussion is performed on the main theoretical uncertainties associated to the calculations.Comment: 04 pages, 2 figures. Final version to be published in European Physical Journal A - "Hadrons and Nuclei

Light vector meson photoproduction in hadron-hadron and nucleus-nucleus collisions at the energies available at the CERN Large Hadron Collider

In this work we analyse the theoretical uncertainties on the predictions for the photoproduction of light vector mesons in coherent pp, pA and AA collisions at the LHC energies using the color dipole approach. In particular, we present our predictions for the rapidity distribution for rh0 and phi photoproduction and perform an analysis on the uncertainties associated to the choice of vector meson wavefunctionand the phenomenological models for the dipole cross section. Comparison is done with the recent ALICE analysis on coherent production of rho at 2.76 TeV in PbPb collisions.Comment: 07 pages, 6 figures. Version to be published in Phys. Rev.

Exclusive photoproduction of quarkonium in proton-nucleus collisions at energies available at the CERN Large Hadron Collider

In this work we investigate the coherent photoproduction of psi(1S), psi(2S) and Upsilon (1S) states in the proton-nucleus collisions in the LHC energies. Predictions for the rapidity distributions are presented using the color dipole formalism and including saturation effects that are expected to be relevant at high energies. Calculations are done at the energy 5.02 TeV and also for the next LHC run at 8.8 TeV in proton-lead mode. Discussion is performed on the main theoretical uncertainties associated to the calculations.Comment: 05 pages, 5 figures. Version to be published in Phys. Rev.

A model for the onset of transport in systems with distributed thresholds for conduction

We present a model supported by simulation to explain the effect of temperature on the conduction threshold in disordered systems. Arrays with randomly distributed local thresholds for conduction occur in systems ranging from superconductors to metal nanocrystal arrays. Thermal fluctuations provide the energy to overcome some of the local thresholds, effectively erasing them as far as the global conduction threshold for the array is concerned. We augment this thermal energy reasoning with percolation theory to predict the temperature at which the global threshold reaches zero. We also study the effect of capacitive nearest-neighbor interactions on the effective charging energy. Finally, we present results from Monte Carlo simulations that find the lowest-cost path across an array as a function of temperature. The main result of the paper is the linear decrease of conduction threshold with increasing temperature: $V_t(T) = V_t(0) (1 - 4.8 k_BT P(0)/ p_c)$, where $1/P(0)$ is an effective charging energy that depends on the particle radius and interparticle distance, and $p_c$ is the percolation threshold of the underlying lattice. The predictions of this theory compare well to experiments in one- and two-dimensional systems.Comment: 14 pages, 10 figures, submitted to PR

Ultraviolet and Infrared Divergences in Implicit Regularization: a Consistent Approach

Implicit Regularization is a 4-dimensional regularization initially conceived to treat ultraviolet divergences. It has been successfully tested in several instances in the literature, more specifically in those where Dimensional Regularization does not apply. In the present contribution we extend the method to handle infrared divergences as well. We show that the essential steps which rendered Implicit Regularization adequate in the case of ultraviolet divergences have their counterpart for infrared ones. Moreover we show that a new scale appears, typically an infrared scale which is completely independent of the ultraviolet one. Examples are given.Comment: 9 pages, version to appear in Mod. Phys. Lett.

Double charmed meson production in pppp and pApA collisions at the LHC within the dipole approach in momentum representation

A study of double charmed meson production in proton-proton and proton-nucleus collisions at the LHC energies is performed. Based on the color dipole formalism developed in the transverse momentum representation and the double parton scattering mechanism, predictions are made for the transverse momentum differential cross section for different pairs of $D$-mesons. The theoretical results consider the center-of-mass energy and forward rapidities associated to the measurements by the LHCb Collaboration. The results considering different unintegrated gluon distributions are presented and compared to data and predictions for proton-nucleus collisions are provided.Comment: 20 pages, 4 figure

The color dipole picture for prompt photon production in pppp and pPbpPb collisions at the CERN-LHC

A study on the prompt photon production within the QCD color dipole picture with emphasis in $pp$ and $pA$ collisions at the LHC energy regimes is performed. We present predictions for the differential cross section as a function of photon transverse momentum at different rapidity bins considering updated phenomenological color dipole models, which take into account the QCD gluon saturation physics. The results are directly compared to the recent experimental measurements provided by CMS and ATLAS Collaborations, showing a reasonable agreement in all rapidity bins with no free parameters. Special attention is given to the IPSAT model given its good description of the data in all rapidity bins from low- to high-$p_{T}$ ranges. As a result, a free-parameter approach has succeeded in describing the LHC data for prompt photon production, while new predictions for the 13-TeV data is presented in view of new data to confirm such prospect.Comment: 12 pages, 18 figure