Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userEffects of Vector Coupling on Chiral and Color-superconducting Phase Transitions -- interplay among the scalar, pairing and vector interaction --
84
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We investigate effects of the vector interaction appearing in chiral effective Lagrangians on the chiral and color superconducting (CSC) phase transitions using Nambu-Jona-Lasinio model. It is shown that the repulsive density-density interaction coming from the vector term enhances competition between the chiral symmerty breaking and CSC phase transition: When the vector coupling is increased, the first order transition between the chiral symmerty breaking and CSC phase becomes weaker, and the coexisting phase in which both the chiral and color-gauge symmetries are dynamically broken comes to exisit in a wider region in the T-mu plane. We find that the critical line of the first order transition can have two endpoints for an intermediate range of the vector coupling.
rate research
Read More
A previous formal derivation of the effective chiral Lagrangian for low-lying pseudoscalar mesons from first-principles QCD without approximations [Wang et al., Phys. Rev. D61, (2000) 54011] is generalized to further include scalar, vector, and axial-vector mesons. In the large Nc limit and with an Abelian approximation, we show that the properties of the newly added mesons in our formalism are determined by the corresponding underlying fundamental homogeneous Bethe--Salpeter equation in the ladder approximation, which yields the equations of motion for the scalar, vector, and axial-vector meson fields at the level of an effective chiral Lagrangian. The masses appearing in the equations of motion of the meson fields are those determined by the corresponding Bethe--Salpeter equation.
Chiral effective theory of scalar and vector diquarks is formulated according to the linear sigma model. The main application is to describe the ground and excited states of singly heavy baryons with a charm or bottom quark. Applying the potential quark model between the diquark and the heavy quark ($Q=c, b$), we construct a heavy-quark--diquark model. The spectra of the positive- and negative-parity states of $Lambda_Q$, $Sigma_Q$, $Xi^{()}_Q$ and $Omega_Q$ are obtained. The masses and interaction parameters of the effective theory are fixed partly from the lattice QCD data and also from fitting low-lying heavy baryon masses. We find that the negative parity excited states of $Xi_Q$ (flavor $bar{bf 3}$) are different from those of $Lambda_Q$, because of the inverse hierarchy of the pseudoscalar diquark. On the other hand, $Sigma_Q, Xi_Q$ and $Omega_Q$ (flavor ${bf 6}$) baryons have similar spectra. We compare our results of the heavy-quark--diquark model with experimental data as well as the quark model.
An alternative for the construction of fundamental theories is the introduction of Galileons. These are fields whose action leads to non higher than second-order equations of motion. As this is a necessary but not sufficient condition to make the Hamiltonian bounded from below, as long as the action is not degenerate, the Galileon construction is a way to avoid pathologies both at the classical and quantum levels. Galileon actions are, therefore, of great interest in many branches of physics, specially in high energy physics and cosmology. This proceedings contribution presents the generalities of the construction of both scalar and vector Galileons following two different but complimentary routes.
The 2-flavor Polyakov-loop extended model is generalized by taking into account the effective four-quark vector-type interaction with the coupling strengths, which are endowed with a dependence on the Polyakov field $Phi$. The effective vertex generates entanglement interaction between the Polyakov loop and the chiral condensate. We investigate the influence of an additional quark vector interaction and the entanglement interaction on the location of the critical end-point at the given chemical potential or quark density. It is shown that the finite value of the vector interaction strength $G_{rm v}$ improves the model agreement with the lattice data. The influence of the non-zero $G_{rm v}$ and entanglement on the thermodynamic observables and the curvature of the crossover boundary in the $T-mu$ plane is also examined.
Effects of the vector-type four-quark interaction on QCD phase structure are investigated in the imaginary chemical potential region, by using the Polyakov-loop extended Nambu-Jona-Lasinio (PNJL) model with the extended Z3 symmetry. In the course to this end, we clarify analytically the Roberge-Weiss periodicity and symmetry properties of various quantities under the existence of a vector-type four-quark interaction. In the imaginary chemical potential region, the chiral condensate and the quark number density are sensitive to the strength of the interaction. Based on this result, we propose a possibility to determine the strength of the vector-type interaction, which largely affects QCD phase structure in the real chemical potential region, by comparing the results of lattice simulations and effective model calculations in the imaginary chemical potential region.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
