Related papers: Lifetime of a Disoriented Chiral Condensate
The pionium lifetime is calculated in the framework of the quasipotential-constraint theory approach, including the sizable electromagnetic corrections. The framework of generalized chiral perturbation theory allows then an analysis of the…
Pionium lifetime corrections to the nonrelativistic formula are calculated in the framework of the quasipotential-constraint theory approach. The calculation extends an earlier evaluation, made in the scheme of standard chiral perturbation…
The relationship between the pionium lifetime and the $\pi\pi$ scattering lengths is established, including the sizable electromagnetic corrections. The bound state formalism that is used is that of constraint theory which provides a…
We suggest two methods for the detection of the formation of disoriented chiral condensates in heavy ion collisions. We show that the variance in the number of charged pions (in a suitable range of momentum space) provides a signature for…
In the near future, the DIRAC collaboration will measure pion-pion scattering lengths with great precision. Those measurements are likely to shed some light on the problem of the size of the chiral quark-antiquark condensate. Although it is…
Evolution of disoriented chiral condenstates is studied with the classical sigma model in 3+1 dimensions. By smoothly connecting a chiral symmetric solution of the formation period to a solution of the decay period, we obtain a complete…
The probability distribution of neutral pion fraction from independent domains of disoriented chiral condensate is characterized. The signal for the condensate is clear for a small number of domains but is greatly reduced for more than…
The probability distribution in $R$, the proportion of neutral pions to all pions emitted in heavy ion collisions in certain kinematic regions, has been suggested as a signal of a disoriented chiral condensate (D$\chi$C). Here we note that…
We address the issue of whether a region of disordered chiral condensate (DCC), in which the chiral condensate has components along the pion directions, can form. We consider a system going through the chiral phase transition either via a…
We report the progress in the measurement of the pionium lifetime by the DIRAC Collaboration at CERN (PS212). Based on data collected in 2001-2003 on Ni targets we have achieved the precision of 11% in the measurement of the pionium…
Chiral Perturbation Theory predicts the lifetime of pionium, a hydrogen-like $\pi^+ \pi^-$ atom, to better than 3% precision. The goal of the DIRAC experiment at CERN is to obtain and check this value experimentally by measuring the…
We investigate the time evolution of a system of quarks interacting with sigma and pion fields starting from an initial configuration consisting of a tube of hot quark plasma undergoing a boost-invariant longitudinal expansion. We work…
One of the main aims of present and upcoming high energy heavy ion collision experiments is to study new phases of matter at extreme temperature and density. It is expected that a nontrivial classical pion field configuration can…
Disoriented chiral condensates or 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…
We study the dynamics of the chiral phase transition expected during the expansion of the quark-gluon plasma produced in a high energy hadron or heavy ion collision, using the $O(4)$ linear sigma model in the mean field approximation.…
Classical considerations suggest that the probability distribution $P(R)$, where $R$ is the ratio of neutral pions to total pions emitted from a disoriented chiral condensate (which has been hypothesized to form in heavy ion reactions) is…
Applying a Langevin description of the linear sigma model we investigate four different scenarios for the evolution of a disoriented chiral condensate: annealing or quench with initial conditions governed by effective `light' or physical…
A theoretical treatment for the weak decays of heavy-flavour hadrons has been developed that is genuinely based on QCD. Its methodology as it applies to total lifetimes and the underlying theoretical issues are sketched. Predictions are…
If a disoriented chiral condensate is created over an extended space-time region following a rapid cooling in hadronic or nuclear collisions, the misalignment of the condensate with the electroweak symmetry breaking can generate observable…
We show that an event-by-event fluctuation of the ratio of neutral pions or resulting photons to charged pions can be used as an effective probe for the formation of disoriented chiral condensates. The fact that the neutral pion fraction…