The quark-hadron phase transition and primordial nucleosynthesis

Abstract

The dynamics and statistical mechanics of the quark-hadron phase transition are explored using the bag model and the known spectrum of hadronic states. We compute the maximum amplitude for isothermal baryon number density fluctuations to emerge from this phase transition and their effects on primordial nucleosynthesis, as a function of the coexistence temperature (or bag constant) and the fractional volume of the universe which will remain in quark-gluon plasma when the release of latent heat no longer compensates the cooling due to expansion. For values of the bag constant, B < (260 MeV) 4 , it is possible to find a pressure, temperature, and baryon-chemical-potential equilibrium between the quark-gluon phase and the hadron phase. We calculate the difference in baryon number concentration between these phases. This difference in baryon number concentration may lead to isothermal baryon density fluctuations. For B > (260 MeV) 4 phase equilibrium is not possible for temperatures below 300 MeV. Thus any differences in baryon concentration are small. In the extreme but interesting case of a Hagedorn limiting hadronic temperature and large bag constant we even find that the QCD vacuum energy can produce a mini-inflationary epoch. We discuss computations of the primordial nucleosynthesis yields corresponding to our estimates of the maximum baryon density fluctuations in a universe with Q = 1 in baryons. We find that 4 He, 3 He, and deuterium are within observed constraints for a large part of the parameter space. However, 7 Li is overproduced. Within the parameter space for an Q = 1 universe we'find only a very small abundance of elements heavier than mass 11 (total mass fraction X < 10" 8).

Inhomogeneous big bang nucleosynthesis revisited

“…Various theories of cosmic phase transitions may lead to the formation of baryon inhomogeneous regions, for example during a first order quark hadron phase transition [15,16,17,18,19,20,21,22,23] or during the electroweak phase transition [24,25,26,27,28].…”

Fundamentals of Cosmological Particle Physics

“…The other side of the conservation of baryons is that the proton, being the lightest baryon, is stable. In the table of the properties of the particles (Nakamura et al 2010) the lower limit of the lifetime of the proton is provided 29 2.1 10 years, p > ⋅ t (2.29) which was obtained in the searches for de-excitation of the residual nucleus after disappearance of the proton in 16 O and does not depend on the possible modes of proton decay, as well as restrictions 31 32 10 5 10 years, p > ÷ ⋅ t (2.30) arising from the negative results of search for specific channels for proton decay. which is the characteristic time for reactions proceeding through the strong interaction.…”

Baryon number penetrability as a measure of isothermal baryon number fluctuations in the early universe

“…Such a fluctuation might also result into the formation of quark nuggets and/or quark stars etc. [1][2][3][4][5][6][7][8]. The basis for the production of isothermal baryon number fluctuation lies in the separation of cosmic phases as follows [1,5].…”