Community Research and Development Information Service - CORDIS

Periodic Report Summary 1 - QCDHI (High Energy QCD for Heavy Ions)

The Large Hadron Collider (LHC) is the world's most important project in high energy physics. With its dedicated experiment on heavy ion (HI) physics, the LHC focuses on the unique possibility of creating and studying a new state of matter, quark gluon plasma (QGP), at energy densities similar to those of the early Universe. The quest for QGP is also the driving force behind the currently operating (though at much smaller energies) Relativistic Heavy Ion Collider (RHIC). The fundamental theory underlying the proton structure as well as the one responsible for nuclear forces is Quantum ChromoDynamics (QCD), the theory of strong interactions.

The study of QCD under extreme conditions of high energies, temperatures and densities has been for long one of the most challenging problems in physics, capturing increasing experimental and theoretical attention. Understanding QCD at high energies is an essential ingredient for success of the LHC program. It is also one of the most active frontiers both in particle phenomenology and nuclear physics
and one of the topics where both fields clearly profit from close collaboration. In particular, a theoretical description of HI collisions and the formation of QGP from first principle calculations is still missing. This project is aimed at achieving a qualitatively new level of understanding of HI collisions, both theoretically and phenomenologically, through the development of a new QCD-based description of these processes.

Both searches for new physics at the LHC in proton-proton and investigations of high energy medium effects in HI collisions require a solid understanding of multiple gluonic interactions. The same effects should be present, though less pronounced, at currently operating accelerators. Gluon densities rise rapidly with energies as has been discovered by Hadron-Electron Ring Accelerator (HERA)
at German Electron Synchrotron DESY. When probed at very high energies, proton appears like a very dense cloud of gluons. Part of this project is to develop a new theory for high energy collisions of dense objects. This is an essential problem for LHC especially for its heavy ion program, where the effects of high gluonic densities get enhanced not only by very high energies but also by the number of nucleons in nuclei.

The main objective of our research project is to further develop the theory of high-energy collisions of dense objects from first-principle calculations and to apply it to phenomenology at the LHC and at the proposed Electron-Ion and Large Hadron-electron Colliders. We focus on collisions involving HIs, where the effects of high densities become enhanced not only by energy but also by the number of nucleons in the nuclei.

The objectives of this project shell be achieved via strengthening and broadening of a long-lasting collaboration between research centers from EU and the US aiming at the development of a unified, QCD-based theoretical framework to describe the structure and collisions of hadrons and nuclei.

The results of this study will facilitate a better understanding of a quantum field theory, such as QCD, beyond naive perturbation
theory. Today, exploring QCD under extreme conditions, such as at high energy/density, is more important than ever due to its relevance for the LHC and future collider programs. In this project we address questions fundamental to understanding the experimental results.

The results obtained so far involve a throughout understanding of the QCD Reggeon Field Theory. Particularly next-to leading order corrections in the QCD coupling constant have been derived. Study of single inclusive particle production, diffraction and vector meson
within the effective theory has been addressed.

The project's webpage is
where we have posted our objectives and results achieved.
So far, the list of publications which came out of this project involves

"QCD Reggeon Calculus From KLWMIJ/JIMWLK Evolution: Vertices, Reggeization and All",
Tolga Altinoluk, Carlos Contreras, Alex Kovner, Eugene Levin, Michael Lublinsky,
and Arthur Shulkin; JHEP 1309 (2013) 115; arXiv:1306.2794.

"JIMWLK Evolution at NLO", Alex Kovner, Michael Lublinsky, and Yair Mulian, Phys.Rev. D89 (2014) 061704 arXiv:1310.0378.

"Conformal symmetry of JIMWLK Evolution at NLO", Alex Kovner, Michael Lublinsky, and Yair Mulian, JHEP 1404 (2014) 030, arXiv:1401.0374.

"Improving the kinematics for low-x QCD evolution equations in coordinate space",
Guillaume Beuf, Phys.Rev. D89 (2014) 074039, arXiv:1401.0313.

"Reggeon field theory for large pomeron loops",
Tolga Altinoluk, Alex Kovner, Eugene Levin, and Michael Lublinsky, JHEP 1404 (2014) 075,

"KLWMIJ reggeon field theory beyond large Nc",
Tolga Altinoluk, Nestor Armesto, Alex Kovner, Eugene Levin, and Michael Lublinsky,
JHEP 1408 (2014) 007 arXiv:1402.5936.

"Remarks on diffractive dissociation within JIMWLK Evolution at NLO",
Michael Lublinsky, Phys. Lett. B 735 (2014) 200, arXiv:1404.0369 .

Next to eikonal corrections in the CGC: gluon production and spin asymmetries in pA collisions",
Tolga Altinoluk, Nestor Armesto, Guillaume Beuf, Mauricio Martínez, Carlos A. Salgado,
JHEP 1407 (2014) 068, arXiv:1404.2219

"NLO JIMWLK evolution unabridged",
Alex Kovner, Michael Lublinsky, and Yair Mulian, JHEP 1408 (2014) 114, arXiv:1405.0418

"Single-inclusive particle production in proton-nucleus collisions at next-to-leading order
in the hybrid formalism,''
Tolga Altinoluk, Nestor Armesto, Guillaume Beuf, Alex Kovner, and Michael Lublinsky,
arXiv:1411.2869, submitted to JHEP.

"Exclusive vector meson production at high energies and gluon saturation,''
Nestor Armesto, and Amir H. Rezaeian, Phys. Rev. D90 (2014), 054003, arXiv:1402.4831

"Linearized fluid/gravity correspondence: from shear viscosity to all order hydrodynamics",
Yanyan Bu and Michael Lublinsky, JHEP 1411 (2014) 064, arXiv:1409.3095


Daphna Tripto, (Head of the Research Liaison Section and LEAR)
Tel.: +972 8 6472443
Fax: +972 8 6472930
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