Ismail Zahed

Bio: Ismail Zahed is an academic researcher from Stony Brook University. The author has contributed to research in topics: Quantum chromodynamics & Instanton. The author has an hindex of 39, co-authored 207 publications receiving 4397 citations. Previous affiliations of Ismail Zahed include Korea Institute for Advanced Study.

Properties of the scalar sigma meson at finite density.

Abstract: The behavior of the scalar \ensuremath{\sigma} meson at high density is discussed in the context of the Nambu--Jona-Lasinio model. The decrease of the \ensuremath{\sigma}-meson mass with increasing density suggests a softening of the equation of state at high density in most of the relativistic mean-field calculations.

Chiral Nuclear Dynamics

Abstract: Part 1 QCD vacuum: QCD vacuum as a magnetic medium monopoles, harons and confinement instantons and chiral symmetry. Part 2 Chiral QCD - mesons: the large Nc limit aspects of current algebra effective Lagrangians soft pion physics vector mesons - open and hidden. Part 3 Chiral QCD-baryons: Wess-Zumino-Witten term Berry phases, spin factors skyrmions Cheshire cat mechanism chiral spin systems anyons. Part 4 Chiral QCD - nuclei: nuclear forces exchange currents nuclei from skyrmions. Part 5 Chiral symmetry breaking and strangeness: piN sigma term the proton spin problem strangeness in the nucleon strange matter heavy flavour systems. Part 6 Hadronic matter under extreme conditions: hot matter RHIC dense matter neutron stars.

High-multiplicity pp and pA collisions: Hydrodynamics at its edge

Abstract: With growing multiplicity, the $pp$ and $pA$ collisions enter the domain where the macroscopic description (thermodynamics and hydrodynamics) becomes applicable. We discuss this situation, first with simplified thought experiments, then with some idealized representative cases, and finally address the real data. For clarity, we do not do it numerically but analytically, using the Gubser solution. We found that the radial flow is expected to increase from central $AA$ to central $pA$, while the elliptic flow decreases, with higher harmonics being comparable. We extensively study the magnitude and distribution of the viscous corrections, in Navier-Stokes and Israel-Stuart approximations, ending with higher gradient resummation proposed by Lublinsky and Shuryak. We found that those corrections grow from $AA$ to $pA$ to $pp$, but remain tractable even for $pp$.

Chiral effective action with heavy-quark symmetry.

Abstract: We derive an effective action combining chiral and heavy-quark symmetry, using approximate bosonization techniques to QCD-inspired models of spontaneous symmetry breaking. We explicitly show that the heavy-quark limit is compatible with the large [ital N][sub [ital c]] (number of color) limit in the meson sector, and estimate the couplings between the light and heavy mesons ([ital D],[ital D][sup *], . . .) and their chiral partners to order one in the heavy-quark mass. The relevance of this effective action to solitons with heavy quarks is briefly discussed.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Random Matrix Theories in Quantum Physics: Common Concepts

Abstract: We review the development of random-matrix theory (RMT) during the last decade. We emphasize both the theoretical aspects, and the application of the theory to a number of fields. These comprise chaotic and disordered systems, the localization problem, many-body quantum systems, the Calogero-Sutherland model, chiral symmetry breaking in QCD, and quantum gravity in two dimensions. The review is preceded by a brief historical survey of the developments of RMT and of localization theory since their inception. We emphasize the concepts common to the above-mentioned fields as well as the great diversity of RMT. In view of the universality of RMT, we suggest that the current development signals the emergence of a new "statistical mechanics": Stochasticity and general symmetry requirements lead to universal laws not based on dynamical principles.