Multi-particle production in proton–nucleus collisions in the color glass condensate

Abstract

We compute multi-gluon production in the Color Glass Condensate approach in dilute-dense collisions, $$\hbox {p}A$$ p A , extending previous calculations up to four gluons. We include the contributions that are leading in the overlap area of the collision but keep all orders in the expansion in the number of colors. We develop a diagrammatic technique to write the numerous color contractions and exploit the symmetries to group the diagrams and simplify the expressions. To proceed further, we use the McLerran–Venugopalan and Golec–Biernat–Wüsthoff models for the projectile and target averages, respectively. We use a form of the Lipatov vertices that leads to the Wigner function approach for the projectile previously employed, that we generalise to take into account quantum correlations in the projectile wave function. We provide analytic expressions for integrated and differential two gluon cumulants and show a smooth dependence on the parameters defining the projectile and target Wigner function and dipole, respectively. For four gluon correlations we find that the second order four particle cumulant is negative, so a sensible second Fourier azimuthal coefficient can be defined. The effect of correlations in the projectile on this result results qualitatively and quantitatively large.

Development of transverse flow at small and large opacities in conformal kinetic theory

“…Beyond studies based on effective macroscopic descriptions of QCD, there have also been attempts to explain the onset of collective behavior in small systems by in- * cwerthmann@physik.uni-bielefeld.de voking a microscopic origin of the correlations. Examples include calculations within the Color Glass Condensate (CGC) effective field theory of high-energy QCD [32][33][34][35][36][37][38][39][40][41][42], as well as more conventional approaches extending general purpose event generators such as PYTHIA or HERWIG to include space-time dependent final state interactions [43][44][45][46].…”

First saturation correction in high energy proton-nucleus collisions. Part III. Ensemble averaging

“…Recently, a new approximation scheme was proposed by Kovner and Rezaeian in [12] and has been applied to study the multiparticle production in high energy nuclear collisions [35,36].…”

Search for Neutrinoless Double-Beta Decay of $^{76}$Ge with a Natural Broad Energy Germanium Detector

“…After combining calibrations of all datasets, a maximum 1.5 keV residual is found in the calibration curve. A quadratic correction [29] is applied in the combined data to reduce the residuals of fitted energy, as shown in Fig. 7.…”