Dilepton from Disoriented Chiral Condensates

Disoriented chiral condensates are manifested as long wavelength pionic oscillations and their interaction with the thermal environment can be a significant source of dileptons. We calculate the yield of such dilepton production within the linear sigma model and illustrate the basic features of the dilepton spectrum in a schematic model. We find that the dilepton yield with invariant mass near and below $2m_{\pi}$ due to the soft pion modes can be up to two orders of magnitude larger than the corresponding equilibrium yield. We conclude with a discussion on how this enhancement can be detected by present dilepton experiments.Comment: 15 pages, 9 figs, uses epsf and sprocl style files Contribution to Proceedings, International Workshop on Astro Hadron Physics `Hadrons in Dense Matter', APCTP, Seoul, Korea, October 199

Lobbying the European Parliament: a necessary evil. CEPS Policy Brief No. 242, May 2011

While the European Parliament is in many ways more transparent and more accessible than many of the EU’s national parliaments, the code of conduct for lobbyists and the Parliament’s own Rules of Procedure are rather vague. As a result of the ‘cash for laws’ scandal, the EP President, Jerzy Buzek, has established a working group to draw up a new set of rules to govern the access and behaviour of lobbyists and to formulate a code of conduct for MEPs

Financial Engineering and Rationality: Experimental Evidence Based on the Monty Hall Problem

Financial engineering often involves redefining existing financial assets to create new financial products. This paper investigates whether financial engineering can alter the environment so that irrational agents can quickly learn to be rational. The specific environment we investigate is based on the Monty Hall problem, a well-studied choice anomaly. Our results show that, by the end of the experiment, the majority of subjects understand the Monty Hall anomaly. Average valuation of the experimental asset is very close to the expected value based on the true probabilities.experiment, behavioral finance

Pair production in a strong electric field: an initial value problem in quantum field theory

We review recent achievements in the solution of the initial-value problem for quantum back-reaction in scalar and spinor QED. The problem is formulated and solved in the semiclassical mean-field approximation for a homogeneous, time-dependent electric field. Our primary motivation in examining back-reaction has to do with applications to theoretical models of production of the quark-gluon plasma, though we here address practicable solutions for back-reaction in general. We review the application of the method of adiabatic regularization to the Klein-Gordon and Dirac fields in order to renormalize the expectation value of the current and derive a finite coupled set of ordinary differential equations for the time evolution of the system. Three time scales are involved in the problem and therefore caution is needed to achieve numerical stability for this system. Several physical features, like plasma oscillations and plateaus in the current, appear in the solution. From the plateau of the electric current one can estimate the number of pairs before the onset of plasma oscillations, while the plasma oscillations themselves yield the number of particles from the plasma frequency. We compare the field-theory solution to a simple model based on a relativistic Boltzmann-Vlasov equation, with a particle production source term inferred from the Schwinger particle creation rate and a Pauli-blocking (or Bose-enhancement) factor. This model reproduces very well the time behavior of the electric field and the creation rate of charged pairs of the semiclassical calculation. It therefore provides a simple intuitive understanding of the nature of the solution since nearly all the physical features can be expressed in terms of the classical distribution function.Comment: Old paper, already published, but in an obscure journa