No Arabic abstract
The contribution of the different terms of the running-coupling Balistky-Kovchegov (rcBK) equation to the description of inclusive HERA data is discussed. Within this framework an alternative definition of the saturation scale is presented. The definition is based on the ratio of the term corresponding to the recombination of two dipoles to the term corresponding to a dipole splitting. A similar ratio is used to study the contribution of the recombination term to the evolution of inclusive HERA data with rapidity. It is found that, although the data are well described, the behaviour of the different terms of the rcBK equation for HERA kinematics is not what it is naively expected from saturation arguments.
A new experimental analysis of the diffractive process $ep rightarrow eXY$, where $Y$ denotes a proton or its low mass excitation with $M_Y<1.6$ GeV, has been performed with the H1 experiment at HERA cite{Aaron:2012ad}. The main results of this study are summarised in this document, together with the comparisons to other measurements and theoretical predictions.
We study ratios of azimuthal-angle distributions in Mueller-Navelet jets after imposing a rapidity veto constraint: the minijet radiation activity is restricted to only allow final-state partons separated at least a distance in rapidity $b$. It is well-known that the asymptotic growth with the rapidity separation of the two tagged jets of the NLLA BFKL Greens function requires a value of $b simeq {cal O} (2)$ in order to avoid unphysical cross sections. We further investigate this point from a phenomenological point of view and work out those values of $b$ which best fit angular distributions measured at the LHC in a realistic set-up where impact factors and parton distribution effects are also taken into account.
We study ridge correlations of the glasma in pp collisions at $sqrt{s_{mathrm{NN}}}=7$ TeV by using the color glass condensate (CGC) formalism. The azimuthal collimation at long range rapidity is intrinsic to glasma dynamics and is reproduced here. When rapidity window enlarges, ridge correlations in two dimensional $Delta y$-$Deltaphi$ distribution and one dimensional $Deltaphi$ distribution at long range rapidity gap are enhanced. The enhancements are demonstrated to be the contributions of source gluons. The quantum evolution of the gluons presents unique correlation patterns in differential correlation function. These characters of two gluon correlations open a way of testing the production mechanism from experimental measurements.
We review recent progress on the calculations on the inclusive forward hadron production within the saturation formalism. After introducing the concept of perturbative parton saturation and nonlinear evolution we discuss the formalism for the forward hadron production at high energy in the leading and next-to-leading order. Numerical results are presented and compared with the experimental data on forward hadron production in $dA$ and $pA$. We discuss the problem of the negativity of the NLO cross section at high transverse momenta, study its origin in detail and present possible improvements which include the corrected kinematics and the suitable choice of the rapidity cutoff.
We present a short summary of parton saturation concepts as seen in deep inelastic scattering.