arXiv subjects

Michael B. Christiansen

Publications and source records attributed to Michael B. Christiansen.

6 recordsLinked to original sources

arXiv2000

Structured Mixed Phase is Favored in Neutron Stars

We give a general thermodynamical argument showing that in neutron stars, the Coulomb structured mixed phase is always favored for any first order phase transition involving systems in equilibrium with baryon number and electric charge as the two independent components. This finding is likely to have important consequences for many neutron star properties, e.g., glitch phenomena, transport and superfluid properties, r-mode instabilities, and the braking index.

astro-ph↗

arXiv2000

Surface Tension between Kaon Condensate and Normal Nuclear Matter Phase

We calculate for the first time the surface tension and curvature coefficient of a first order phase transition between two possible phases of cold nuclear matter, a normal nuclear matter phase in equilibrium with a kaon condensed phase, at densities a few times the saturation density. We find the surface tension is proportional to the difference in energy density between the two phases squared. Furthermore, we show the consequences for the geometrical structures of the mixed phase region in a neutron star.

nucl-th↗

arXiv1997

Finite size effects and the mixed quark-hadron phase in neutron stars

We demonstrate that the form and location (not the size or spacing) of the energetically preferred geometrical structure of the crystalline quark-hadron mixed phase in a neutron star is very sensitive to finite size terms beyond the surface term. We consider two independent approaches of including further finite size terms, namely the multiple reflection expansion of the bag model and an effective surface tension description. Thus care should be taken in any model requiring detailed knowledge of these crystalline structures.

astro-ph↗

arXiv1996

Color Singlet Strangelets

When considering strangelets at finite temperature it is important to obey the constraint that any observed state must be color singlet. This constraint results in an increase in strangelet masses as calculated at fixed entropy per baryon. We use the color singlet partition function for an MIT bag, derived using the group theoretical projection method, to calculate strangelet masses. Mean shell effects are included in a liquid drop model, by using a density of states obtained from the multiple reflection expansion. Another important effect of the color singlet restriction, namely many orders of magnitude suppression of thermal nucleation of quark-gluon plasma in collisions, will also briefly be described.

hep-ph↗

arXiv1996

Large nucleation distances from impurities in the cosmological quark-hadron transition

We calculate the mean nucleation distance, $d_{nuc}$, in a first order cosmological quark-hadron phase transition. For homogeneous nucleation we find that self-consistent inclusion of curvature energy reduces $d_{nuc}$ to $\lesssim 2$cm. However, impurities can lead to heterogeneous nucleation with $d_{nuc}$ of several meters, a value high enough to change the outcome of Big Bang nucleosynthesis.

astro-ph↗

arXiv1996

Color singlet suppression of quark-gluon plasma formation

The rate of quark-gluon plasma droplet nucleation in superheated hadronic matter is calculated within the MIT bag model. The requirements of color singletness and (to less extent) fixed momentum suppress the nucleation rate by many orders of magnitude, making thermal nucleation of quark-gluon plasma droplets unlikely in ultrarelativistic heavy-ion collisions if the transition is first order and reasonably described by the bag model.

nucl-th↗