scholarly journals Mesons and diquarks in a color superconducting regime

Author(s):  
Eric Blanquier

The behavior of the mesons and diquarks is studied at finite temperatures, chemical potentials and densities, notably when the color superconductivity is taken into account. The Nambu and Jona-Lasinio model complemented by a Polyakov loop (PNJL description) has been adapted in order to model them in this regime. This paper focuses on the scalar and pseudoscalar mesons and diquarks, in a three-flavor and three-color description, with the isospin symmetry and at zero strange density. An objective of this work is to underline the modifications carried out by the color superconducting regime on the used equations and on the obtained results. It has been observed that the two-flavor color-superconducting (2SC) phase affects the masses and the coupling constants of the mesons and diquarks in a non-negligible way. This observation is particularly true at high densities and low temperatures for the pions, [Formula: see text] and the diquarks [Formula: see text] whose color is [Formula: see text]. This reveals that the inclusion of the color superconductivity in the modeling is relevant to describe the mesons and diquarks near the first-order chiral phase transition.

2004 ◽  
Vol 19 (10) ◽  
pp. 727-743 ◽  
Author(s):  
P. C. W. DAVIES

Recent advances in string theory and inflationary cosmology have led to a surge of interest in the possible existence of an ensemble of cosmic regions, or "universes", among the members of which key physical parameters, such as the masses of elementary particles and the coupling constants, might assume different values. The observed values in our cosmic region are then attributed to an observer selection effect (the so-called anthropic principle). The assemblage of universes has been dubbed "the multiverse". In this paper we review the multiverse concept and the criticisms that have been advanced against it on both scientific and philosophical grounds.


The thermal conductivity between 0.4 and 4.2 K and in magnetic fields up to 50 kOe of KMgF 3 doped with Ni 2+ has been measured. The results are analysed to give values of the average spin-lattice coupling constants ( x Sl ) for the Ni 2+ ion. These are in agreement with values calculated using the magneto-elastic constants (GX1 and 6r44) derived from acoustic paramagnetic resonance (a.p.r.) experiments. Below IK the thermal resistivity as a function of magnetic field shows a number of anomalies, for which possible causes are discussed; it is concluded that they result from phonon interactions with exchange-coupled pairs of Ni 2+ ions. Such pairs are also observed in a.p.r. experiments.


2011 ◽  
Vol 26 (14) ◽  
pp. 2327-2352 ◽  
Author(s):  
AMIR H. FARIBORZ

A procedure for implementation of the generating equations in the linear sigma model of low energy QCD is presented. For any explicit symmetry breaking term, this procedure computes the masses of scalar and pseudoscalar mesons as well as various three-point and four-point interaction vertices that are needed in calculation of different decay widths and scattering amplitudes.


2019 ◽  
Vol 34 (15) ◽  
pp. 1950073
Author(s):  
Vo Quoc Phong ◽  
Minh Anh Nguyen

Our analysis shows that SM-like electroweak phase transition (EWPT) in the [Formula: see text] (2-2-1) model is a first-order phase transition at the 200 GeV scale (the SM scale). Its strength [Formula: see text] is about 1–2.7 and the masses of new gauge bosons are larger than 1.7 TeV when the second VEV is larger than 535 GeV in a three-stage EWPT scenario and the coupling constant of [Formula: see text] group must be larger than 2. Therefore, this first-order EWPT can be used to fix VEVs and the coupling constant of the gauge group in electroweak models.


1947 ◽  
Vol 25b (2) ◽  
pp. 135-150 ◽  
Author(s):  
Paul A. Giguère

The decomposition of hydrogen peroxide vapour has been investigated at low pressures (5 to 6 mm.) in the temperature range 50° to 420 °C., for the purpose of determining the effect of the nature and treatment of the active surfaces. The reaction was followed in an all-glass apparatus and, except in one case, with one-litre round flasks as reaction vessels. Soft glass, Pyrex, quartz, and metallized surfaces variously treated were used. In most cases the decomposition was found to be mainly of the first order but the rates varied markedly from one vessel to another, even with vessels made of the same type of glass. On a quartz surface the decomposition was preceded by an induction period at low temperatures. Fusing the glass vessels slowed the reaction considerably and increased its apparent activation energy; this effect was destroyed by acid washing. Attempts to poison the surface with hydrocyanic acid gave no noticeable result. The marked importance of surface effects at all temperatures is considered as an indication that the reaction was predominantly heterogeneous under the prevailing conditions. Values ranging from 8 to 20 kcal. were found for the apparent energy of activation. It is concluded that the decomposition of hydrogen peroxide vapour is not very specific as far as the nature of the catalyst is concerned.


An attempt is made to examine theoretically the properties of paramagnetic alums at low temperatures. The model taken is a lattice of freely suspended magnets, all interactions except purely magnetic being neglected. Even with this simplification it is impossible at present to make rigorous calculations of the partition function, either on classical or quantum lines. A simple model is proposed, which is really a generalization of the Bragg - Williams theory enabling one to take account of the effect of a magnetic field. The few configurations whose energies are known are used to fix arbitrary constants in the expression assumed for the energy. The theory predicts that the state of lowest energy is either a spontaneously magnetized, state for a long thin specimen, or a state in which alternate rows of magnets point in opposite directions for a sphere, spontaneous magnetization appearing in an ellipsoid with an eccentricity greater than a certain critical value. The transition curve bounding the region in which the antiparallel state is stable consists partly of a line of Curie points corresponding to transitions of the second, order, passing smoothly into a line of critical points corresponding to a transition of the first order. The effect of shape on the magnetic properties of the specimen seems to be experimentally verified, but the rough nature of the theory prevents it being more than qualitative.


2002 ◽  
Vol 17 (12) ◽  
pp. 751-761 ◽  
Author(s):  
G. KOUTSOUMBAS ◽  
G. K. SAVVIDY

We perform Monte–Carlo simulations of a three-dimensional spin system with a Hamiltonian which contains only four-spin interaction term. This system describes random surfaces with extrinsic curvature – gonihedric action. We study the anisotropic model when the coupling constants βS for the space-like plaquettes and βT for the transverse-like plaquettes are different. In the two limits βS = 0 and βT = 0 the system has been solved exactly and the main interest is to see what happens when we move away from these points towards the isotropic point, where we recover the original model. We find that the phase transition is of first order for βT = βS ≈ 0.25, while away from this point it becomes weaker and eventually turns to a crossover. The conclusion which can be drawn from this result is that the exact solution at the point βS = 0 in terms of 2D-Ising model should be considered as a good zero-order approximation in the description of the system also at the isotropic point βS = βT and clearly confirms the earlier findings that at the isotropic point the original model shows a first-order phase transition.


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