Conveners
CGC: 1
- Michael Lublinsky
CGC: 2
- Tuomas Lappi (University of Jyväskylä)
CGC: 3
- Vladimir Skokov (Brookhaven national laboratory)
CGC: 4
- Alexander Kovner (University of Connecticut)
CGC: 5
- Wojciech Florkowski (Institute of nuclear Physics, Krakow)
Heavy quarks (charm and beauty) are primarily produced in hard-scattering processes with large momentum transfer due to their large masses. They are effective probes to study cold-nuclear-matter (CNM) effects such as gluon saturation, shadowing, $k_{\rm T}$ broadening and energy loss in CNM in p-Pb collisions. In recent years, effects ascribed to the collective expansion of the deconfined...
The leading order result of single inclusive gluon production in high energy pA collisions has been calculated by various approaches for more than two decades . The first saturation correction to the leading order result, terms that are enhanced by $\alpha_s^2 A^{1/3}$ with $\alpha_s$ the strong coupling constant and $A$ the atomic number of nucleus, was only analytically attempted recently...
Within the Color Glass Condensate effective theory or other related frameworks, the theoretical description of low-x (or high-energy) QCD processes sensitive to the nonlinear gluon saturation physics relies on two main pillars.
The first one is the semiclassical approach: due to the high density of low x gluons in an incoming proton or nucleus target, scattering processes off that target...
The ultra-peripheral collisions (UPCs) of relativistic heavy ion beams lead to a diverse set of photon-nucleus interactions. The measurements of particles and their interaction produced in photo-nuclear reactions can shed light on the QCD dynamics of novel, extremely asymmetric colliding systems, with energies between those available at RHIC and the LHC. Understanding the hadronic fluctuation...
We present predictions for proton and nuclear structure functions using numerical solutions to the Balistky-Kovchegov equation with the collinearly improved kernel and including the impact-parameter dependence. Two different approaches to the nuclear case are studied: a solution obtained using a newly proposed type of initial condition which represent the given nucleus and the solutions based...
In recent years there has been a great effort to search for collectivity in small collision systems. Ultra-peripheral pPb events offer the possibility to study photon-proton collisions at center of mass energies of several hundred GeV, and provide a new arena for the search of collectivity at very small systems. The CMS experiment has collected a large dataset of photon-proton collisions by...
The Color Glass Condensate (CGC) effective field theory (EFT) at leading order describes well the Deep Inelastic Scattering (DIS) inclusive cross section data at small-x as measured by the HERA experiments [1-3]. Recently the inclusive DIS impact factors have been calculated in Next-to-Leading Order (NLO) accuracy in CGC EFT [4-6], and the soft gluon divergence present at NLO has been...
We present the forward rapidity gap spectra from proton-lead collisions for both pomeron-lead and pomeron-proton topologies measured at CMS. The analysis is performed over 10.4 units of pseudorapidity at a center-of-mass energy of $\sqrt{s}_{NN}=8.16$ TeV, i.e. almost 300 times higher than previous measurements of diffractive production in proton-nucleus collisions. For the pomeron-lead...
Within the Color Glass Condensate effective theory, most observables are computed by adopting the eikonal approximation. At asymptotic energies, this corresponds to treating the dense target as an infinitely thin shockwave. However, finite longitudinal width corrections to the shockwave approximation might be important at realistic energies. In such a case, the propagation of a parton through...
The ridge phenomena observed in small size systems such as high multiplicity pp and pA collisions triggered a lot of activity to study the two particle correlations from the initial state point of view. In this talk, we will discuss the multiplicity and mean transverse momentum dependence of v2 by adopting CGC-based calculations in pA collisions. More precisely, we apply CGC techniques to...
Two-particle azimuthal correlation has been proposed to be one of the most direct and sensitive channels to access the underlying nonlinear gluon dynamics.
In hadron collisions at RHIC, forward particle production probes gluons at small x where the gluon density rises sharply.
During the 2015 RHIC run, STAR has collected data for measuring azimuthal correlations of neutral pions detected...
Abstract: We analyze the entanglement in the context of high energy QCD. First, in order to provide a firm connection to experimental observables, we define the “entropy of ignorance” which quantifies the entropy associated with ability to perform only a partial set of measurement on a quantum system. For the parton model the entropy of ignorance is equal to the Boltzmann entropy of a...
Particle production at forward rapidities in proton-nucleus collisions provides access to the target structure at very small momentum fraction x, where non-linear QCD dynamics is expect to play an important role. Recently, the CASTOR calorimeter at CMS [1], covering pseudodapidity region -6.6 < eta < -5.2, has released first jet spectra measurements in proton-lead collisions, probing nuclear...
Exclusive vector meson production is a powerful process to probe the gluonic structure of protons and nuclei at small Bjorken-$x$, and it also makes it possible to study the geometry of the nuclei in the transverse plane. An accurate description of the process requires us to use a vector meson light front wave function that correctly represents the meson. Currently, the light front wave...
Particle production at LHC energies results from the interplay of hard- and soft-QCD processes and is sensitive to non-linear QCD evolution in the initial state. In particular, for p-Pb collisions, one can use the proton to probe the low-$x$ dense gluonic fields of the Pb nuclei. The multiplicity and rapidity dependence of charged- and neutral-particle production, therefore, provides important...
The Colour Glass Condensate effective field theory is a useful framework for studying heavy ion collisions at ultra-relativistic energies, such as those reached at the Large Hadron Collider. In this framework, we study the rapidity evolution of Wilson lines that appear explicitly in cross section expressions. The next-to-leading order BK (Balitsky-Kovchegov) equation for the 2-point Wilson...
Color charge correlations in the proton at moderately small x
are extracted from its light-cone wave function. The charge
fluctuations are far from Gaussian. Correlators are described by
n-body GPDs which exhibit interesting dependence on impact parameter
as well as on the relative transverse momentum (or distance) of the
gluon probes.
This analysis provides initial conditions for...
