Unfolding of event-by-event net-charge distributions in heavy-ion collision

We discuss a method to obtain the true event-by-event net-charge multiplicity distributions from a corresponding measured distribution which is subjected to detector effects such as finite particle counting efficiency. The approach is based on the Bayes method for unfolding of distributions. We are able to faithfully unfold back the measured distributions to match with their corresponding true distributions obtained for a widely varying underlying particle production mechanism, beam energy and collision centrality. Particularly the mean, variance, skewness, kurtosis, their products and ratios of net-charge distributions from the event generators are shown to be successfully unfolded from the measured distributions constructed to mimic a real experimental distribution. We demonstrate the necessity to account for detector effects before associating the higher moments of net-charge distributions with physical quantities or phenomena. The advantage of this approach being that one need not construct new observable to cancel out detector effects which loose their ability to be connected to physical quantities calculable in standard theories

Phase separation transition in anti-ferromagnetically interacting particle systems

One dimensional non-equilibrium systems with short-range interaction can undergo phase transitions from homogeneous states to phase separated states as interaction ($\epsilon$) among particles is increased. One of the model systems where such transition has been observed is the extended Katz-Lebowitz-Spohn (KLS) model with ferro-magnetically interacting particles at $\epsilon=4/5$. Here, the system remains homogeneous for small interaction strength ($\epsilon<4/5$), and for anti-feromagnetic interactions ($\epsilon<0$). We show that the phase separation transitions can also occur in anti-ferromagnetic systems if interaction among particles depends explicitly on the size of the block ($n$) they belong to. We study this transition in detail for a specific case $\epsilon = \delta/n$, where phase separation occurs for $\delta < -1$.Comment: 4 pages, 5 figure

Influence Functional for Decoherence of Interacting Electrons in Disordered Conductors

We have rederived the controversial influence functional approach of Golubev and Zaikin (GZ) for interacting electrons in disordered metals in a way that allows us to show its equivalence, before disorder averaging, to diagrammatic Keldysh perturbation theory. By representing a certain Pauli factor (1-2 rho) occuring in GZ's effective action in the frequency domain (instead of the time domain, as GZ do), we also achieve a more accurate treatment of recoil effects. With this change, GZ's approach reproduces, in a remarkably simple way, the standard, generally accepted result for the decoherence rate. -- The main text and appendix A.1 to A.3 of the present paper have already been published previously; for convenience, they are included here again, together with five additional, lengthy appendices containing relevant technical details.Comment: Final version, as submitted to IJMPB. 106 pages, 11 figures. First 16 pages contain summary of main results. Appendix A summarizes key technical steps, with a new section A.4 on "Perturbative vs. Nonperturbative Methods". Appendix C.4 on thermal weighting has been extended to include discussion [see Eqs.(C.22-24)] of average energy of electron trajectorie