156 research outputs found
Scaling of transverse energies and multiplicities with atomic number and energy in ultrarelativistic nuclear collisions
We compute how the initial energy density and produced gluon, quark and
antiquark numbers scale with atomic number and beam energy in ultrarelativistic
heavy ion collisions. The computation is based on the argument that the effect
of all momentum scales can be estimated by performing the computation at one
transverse momentum scale, the saturation momentum. The initial numbers are
converted to final ones by assuming kinetic thermalisation and adiabatic
expansion. The main emphasis of the study is at LHC and RHIC energies but it is
observed that even at SPS energies this approach leads to results which are not
unreasonable: what is usually described as a completely soft nonperturbative
process can also be described in terms of gluons and quarks. The key element is
the use of the saturation scale.Comment: 13 pages, includes 7 eps-figure
Gluon Distribution Functions for Very Large Nuclei at Small Transverse Momentum
We show that the gluon distribution function for very large nuclei may be
computed for small transverse momentum as correlation functions of an
ultraviolet finite two dimensional Euclidean field theory. This computation is
valid to all orders in the density of partons per unit area, but to lowest
order in . The gluon distribution function is proportional to ,
and the effect of the finite density of partons is to modify the dependence on
transverse momentum for small transverse momentum.Comment: TPI--MINN--93--52/T, NUC--MINN--93--28/T, UMN--TH--1224/93, LaTex, 11
page
An Evolutionary Learning Approach for Adaptive Negotiation Agents
Developing effective and efficient negotiation mechanisms for real-world applications such as e-Business is challenging since negotiations in such a context are characterised by combinatorially complex negotiation spaces, tough deadlines, very limited information about the opponents, and volatile negotiator preferences. Accordingly, practical negotiation systems should be empowered by effective learning mechanisms to acquire dynamic domain knowledge from the possibly changing negotiation contexts. This paper illustrates our adaptive negotiation agents which are underpinned by robust evolutionary learning mechanisms to deal with complex and dynamic negotiation contexts. Our experimental results show that GA-based adaptive negotiation agents outperform a theoretically optimal negotiation mechanism which guarantees Pareto optimal. Our research work opens the door to the development of practical negotiation systems for real-world applications
Some Features of the Glasma
We discuss high energy hadronic collisions within the theory of the Color
Glass Condensate. We point out that the initial electric and magnetic fields
produced in such collisions are longitudinal. This leads to a novel string like
description of the collisions, and a large Chern-Simons charge density made
immediately after the collision. The presence of the longitudinal magnetic
field suggests that essential to the description of these collisions is the
decay of Chern-Simons charge.Comment: 17 pages, 5 figures. V2: references added and correcte
Hot Spots and Turbulent Initial Conditions of Quark-Gluon Plasmas in Nuclear Collisions
As a result of multiple mini-jet production, initial conditions of the QCD
plasma formed in ultrarelativistic nuclear collisions may be inhomogeneous,
with large fluctuations of the local energy density (hot spots), and turbulent,
with a chaotic initial transverse velocity field. Assuming rapid local
thermalization, the evolution of such plasmas is computed using longitudinal
boost-invariant 3+1-dimensional hydrodynamics. We compare the evolution in case
that the speed of sound in the plasma is constant to one resulting from an
equation of state involving a strong first order transition, with a minimum of
the velocity of sound as a function of energy density. We find that azimuthally
asymmetric fluctuations and correlations of the transverse energy flow can
develop in both cases due to the initial inhomogeneities. Hot spots also
enhance significantly high-transverse momenta direct photon yields. In the case
with a phase transition, the hadronization surface evolves into an unusual
foam-like structure. Also in that case, we find that hadronization is
considerably delayed relative to the ideal gas case, just as previous studies
have found for homogeneous initial conditions. The time-delay signature of a
rapid cross-over transition region in the QCD equation of state (as observable
via meson interferometry) is thus found to be remarkably robust to
uncertainties in the initial conditions in heavy-ion reactions.Comment: 28 pages, LaTeX, 20 figures, available as uucompressed file
(including LaTeX-file) ftp://nt1.phys.columbia.edu/pub/turb/turb2.uu
(username: ftp, password: complete email address
On the attainment of the maximum sustainable yield in the Verhulst-Lotka-Volterra model
We reformulate the Verhulst-Lotka-Volterra model of natural resource extraction under the alternative assumptions of Cournot behaviour and perfect competition, to revisit the tragedy of commons vs the possibility of sustainable harvesting. We stress the different impact of demand elasticity on the regulator’s possibility of driving industry harvest to the maximum sustainable yield in the two settings. The presence of a flat demand function offers the authority a fully effective regulatory tool in the form of the exogeneous price faced by perfectly competitive firms, to drive their collective harvest rate at the maximum sustainable yield. The same cannot happen under Cournot competition, as in this case the price is endogenous and the regulator’s policy is confined to limiting access to the common pool
Unanimously acceptable agreements for negotiation teams in unpredictable domains
A negotiation team is a set of agents with common and possibly also conflicting preferences that forms
one of the parties of a negotiation. A negotiation team is involved in two decision making processes
simultaneously, a negotiation with the opponents, and an intra-team process to decide on the moves
to make in the negotiation. This article focuses on negotiation team decision making for circumstances
that require unanimity of team decisions. Existing agent-based approaches only guarantee unanimity
in teams negotiating in domains exclusively composed of predictable and compatible issues. This article
presents a model for negotiation teams that guarantees unanimous team decisions in domains consisting
of predictable and compatible, and alsounpredictable issues. Moreover, the article explores the influence of
using opponent, and team member models in the proposing strategies that team members use. Experimental
results show that the team benefits if team members employ Bayesian learning to model their
teammates’ preferences.
2014 Elsevier B.V. All rights reserved.This research is partially supported by TIN2012-36586-C03-01 of the Spanish government and PROMETEOII/2013/019 of Generalitat Valenciana. Other part of this research is supported by the Dutch Technology Foundation STW, applied science division of NWO and the Technology Program of the Ministry of Economic Affairs; the Pocket Negotiator Project with Grant No. VICI-Project 08075.Sánchez Anguix, V.; Aydogan, R.; Julian Inglada, VJ.; Jonker, C. (2014). Unanimously acceptable agreements for negotiation teams in unpredictable domains. Electronic Commerce Research and Applications. 13(4):243-265. https://doi.org/10.1016/j.elerap.2014.05.002S24326513
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