Spontaneous symmetry breaking in the linear sigma model at finite chemical potential: One-loop corrections

We investigate spontaneous symmetry breaking within the linear sigma model with the SU(2)xU(1) internal symmetry at finite chemical potential, which was suggested as a model for kaon condensation in the CFL phase of dense quark matter. One-loop corrections to the scalar field effective potential as well as its propagator are calculated. Particular attention is paid to the type-II Goldstone boson that appears in the Bose--Einstein condensed phase. Furthermore, we show that the type-I Goldstone boson -- the superfluid phonon -- is allowed to decay due to the nonlinearity of its dispersion relation at high momentum, and determine its decay width.Comment: 13 pages, REVTeX4, 37 eps figures; v2: substantial error in Sec. IV corrected, references added, other minor corrections; version to appear in Phys. Rev.

Goldstone boson counting in linear sigma models with chemical potential

We analyze the effects of finite chemical potential on spontaneous breaking of internal symmetries within the class of relativistic field theories described by the linear sigma model. Special attention is paid to the emergence of ``abnormal'' Goldstone bosons with quadratic dispersion relation. We show that their presence is tightly connected to nonzero density of the Noether charges, and formulate a general counting rule. The general results are demonstrated on an SU(3)xU(1) invariant model with an SU(3)-sextet scalar field, which describes one of the color-superconducting phases of QCD.Comment: 10 pages, REVTeX4, 4 eps figures, v2: general discussion in Sec. IV expanded and improved, references added, other minor corrections throughout the tex

Root effect haemoglobins in fish may greatly enhance general oxygen delivery relative to other vertebrates

The teleost fishes represent over half of all extant vertebrates; they occupy nearly every body of water and in doing so, occupy a diverse array of environmental conditions. We propose that their success is related to a unique oxygen (O2) transport system involving their extremely pH-sensitive haemoglobin (Hb). A reduction in pH reduces both Hb-O2 affinity (Bohr effect) and carrying capacity (Root effect). This, combined with a large arterial-venous pH change (ΔpHa-v) relative to other vertebrates, may greatly enhance tissue oxygen delivery in teleosts (e.g., rainbow trout) during stress, beyond that in mammals (e.g., human). We generated oxygen equilibrium curves (OECs) at five different CO2 tensions for rainbow trout and determined that, when Hb-O2 saturation is 50% or greater, the change in oxygen partial pressure (ΔPO2) associated with ΔpHa-v can exceed that of the mammalian Bohr effect by at least 3-fold, but as much as 21-fold. Using known ΔpHa-v and assuming a constant arterial-venous PO2 difference (Pa-vO2), Root effect Hbs can enhance O2 release to the tissues by 73.5% in trout; whereas, the Bohr effect alone is responsible for enhancing O2 release by only 1.3% in humans. Disequilibrium states are likely operational in teleosts in vivo, and therefore the ΔpHa-v, and thus enhancement of O2 delivery, could be even larger. Modeling with known Pa-vO2 in fish during exercise and hypoxia indicates that O2 release from the Hb and therefore potentially tissue O2 delivery may double during exercise and triple during some levels of hypoxia. These characteristics may be central to performance of athletic fish species such as salmonids, but may indicate that general tissue oxygen delivery may have been the incipient function of Root effect Hbs in fish, a trait strongly associated with the adaptive radiation of teleosts

Physiological Responses to Acute Silver Exposure in the Freshwater Crayfish (\u3cem\u3eCambarus diogenes diogenes\u3c/em\u3e)—A Model Invertebrate?

Adult crayfish (Cambarus diogenes diogenes) exposed to 8.41 ± 0.17 μg silver/L (19.4% as Ag+) in moderately hard freshwater under flow-through conditions for 96 h exhibited ionoregulatory disturbance, elevated metabolic ammonia (Tamm) production and substantial silver accumulation in the gills, hemolymph, and hepatopancreas. The ionoregulatory disturbance included both a generally reduced unidirectional Na1 influx and an increased unidirectional Na+ efflux, leading to a substantial net loss of Na+ from the silver-exposed crayfish. The Na+ uptake in silver-exposed crayfish differed overall from controls, while the increased Na+ efflux recovered to control values 48 h into the 96 h of exposure. The general inhibition of Na+ uptake could be explained by a reduced sodium/potassium-adenosine triphosphatase (Na/K-ATPase) activity in terminally obtained gill samples from the silver exposed crayfish. The silver-induced effect on Na+ uptake and loss translated to reduced hemolymph Na+ concentrations but not significantly reduced hemolymph Cl- concentrations. Hemolymph Tamm and Tamm efflux both increased in silver-exposed crayfish, indicating an increased metabolic Tamm production. The present study demonstrates that the toxic mechanism of waterborne silver exposure in freshwater crayfish resembles that of freshwater teleost fish. The crayfish might therefore be a useful model system for extending current environmental regulatory strategies, currently based on teleost fish, to invertebrates

Coulomb corrections to the three-body correlation function in high-energy heavy ion reactions

Starting from an asymptotically correct three-body Coulomb wave-function, we determine the effect of Coulomb final state interaction on the three-particle Bose-Einstein correlation function of similarly charged particles. We numerically estimate that the Riverside approximation is not precise enough to determine the three-body Coulomb correction factor in the correlation function, if the characteristic HBT radius parameter is 5 - 10 fm, which is the range of interest in high-energy heavy ion physics.Comment: 14 pages, 4 figure