123325200
Production of antinuclei and hypernuclei in a relativistic Hagedorn resonance gas model
119271689
Event-plane correlators
Introduction.−High-energy heavy-ion collision experiments at the Relativistic Heavy-Ion Collider (RHIC), BNL and the Large Hadron Collider (LHC), CERN have firmly established the formation of strongly interacting matter which exhibits a strong collective flow [1–3]. This not only suggests that the matter formed is close to local thermal equilibrium but also provides a window to the initial state of the fireball immediately after the collision. Collective flow in the plane transverse to the beam axis is typically measured in terms of two-particle angular correlations [4–7] and its small anisotropies captured in its Fourier harmonics [8–11]. Recently, a new tool, namely correlations among event planes corresponding to different harmonics [12–14], is emerging with a promise to throw additional light on the initial-state phenomena. Pair correlations (i.e., the single-particle anisotropic flow vn extracted from two-particle correlations) are reasonably well understood [8]. Event-plane correlators represent higher-order correlations, involving at least three particles. Such higher-order correlations thus open a new direction in heavy-ion physics, much in the same way as studies of non-Gaussian fluctuations [15] in the early Universe. They bring in a large number of new observables which provide new, detailed insight into the hydrodynamic response and on the initial stage, and will significantly improve our understanding of heavy-ion collisions. The ATLAS collaboration [14] has recently released preliminary measurements of eight two-plane correlators (e.g., the correlation between the second and fourth harmonics) and six three-plane correlators (e.g., the mixed correlation between second, third and fifth harmonics) in Pb-Pb collisions at √ sNN = 2.76 TeV, as a function of the centrality of the collision. These correlators are qualitatively understood within event-by-event hydrodynamics [16] and provide new insight [17] into the interplay between the linear and nonlinear [18] hydrodynamic response [19, 20] to the initial density profile. The ATLAS analysis is very demanding in terms of detector acceptance: each event plane is determined in a separate pseudorapidity window; windows must be pairwise separated by gaps in order to suppress nonflow correlations; finally, each window must be wide enough to achieve a significant resolution in every Fourier harmonic up to order six. In this article, we show that the analysis can be done more simply, and that even three- and four-plane correlators can be safely analyzed with just two symmetric pseudorapidity windows, in the same way as two-plane correlators. The analysis can thus be performed by other experiments with smaller detector acceptance. We also explain in detail how to generalize the scalar-product method used earlier for two-particle flow analysis [21], to mixed correlations, so as to eliminate the ambiguity brought about by the event-plane method [22]. We carry out realistic simulations within a multiphase transport (AMPT) model [23]. Results are for the first time in quantitative agreement with the ATLAS measurements. In addition, we present predictions for several new correlators, in particular four-plane correlators. Method.−The azimuthal distribution of outgoing particles is decomposed in Fourier harmonics in each collision event. The flow vector in harmonic n is defined as [24],
120847496
Multiplicity scaling in nuclear fragmentation
17948221
Noncommutative Open String, D-brane and Duality
Abstract We consider open strings ending on D-branes in the presence of constant metric, G , antisymmetric tensor, B and gauge field, A . The Hamiltonian is manifestly invariant under a global noncompact group; strikingly similar to toroidally compactified closed string Hamiltonian. The evolution equations for the string coordinates, { X i } and their dual partners, { Y i }, are combined to obtain equations of motion invariant under the noncompact symmetry transformations. We show that one can start from a noncommutative theory, with nonvanishing G and B and mixed boundary conditions and then go over to a dual theory whose coordinates obey Dirichlet boundary conditions. It is possible to generate B -field by implementing the noncompact symmetry transformation. The connection between this duality transformation and Seiberg-Witten map is discussed.
15460339
A NOTE ON NONCOMMUTATIVE STRING THEORY AND ITS LOW ENERGY LIMIT
The noncommutative string theory is described by embedding open string theory in a constant second rank antisymmetric Bμν field and the noncommutative gauge theory is defined by a deformed ⋆ product. As a check, the study of various scattering amplitudes in both noncommutative string and noncommutative gauge theory confirms that in the α′ → 0 limit, the noncommutative string theoretic amplitude goes over to the noncommutative gauge theoretic amplitude and the couplings are related as . Furthermore, we show that in this limit there will not be any correction to the gauge theoretic action because of the absence of massive modes. We get sin/cos factors in the scattering amplitudes depending on the odd/even number of external photons.
117480588
Weak Gravity Conjecture, Central Charges and $\eta/s$
We correlate the weak gravity conjecture (WGC), the KSS conjecture with chemical potential at extremality and the central charges by going through a particular example in five dimensional AdS spacetime with two unknown coefficients $c_1, c_2$, assuming WGC exists in AdS spacetime. The result that follows from this example suggests that WGC makes the KSS conjecture to hold in the extremal limit but only when one of the coefficient vanishes ($c_1=0, c_2\neq 0$ or $c_2=0, c_1\neq 0$) and when both the coefficients are non zero it can respect and/or violate the KSS conjecture depending on the choice to $c_1$ at extremality, even though $\eta/s$ do not depend on $c_1$ at extremality. Moreover, WGC is not fully compatible with the calculation of central charges even though the bounds on coefficient $c_1$ that follows from demanding WGC stays within the bounds that central charges predict. As usual, the KSS conjecture is violated, of course, in the non-extremal limit.
17697869
Coincident Dp-branes in codimension two
We derive the mass shell condition for N coincident D0 branes in codimension two i.e. in space-time dimension three. Using this we present the action for this system in first order formalism. Our analysis is restricted to flat space-time.