CHIRAL SYMMETRY AND MESON LOOP MODEL FOR NON-LEPTONIC K AND D WEAK DECAYS

1991 ◽  
Vol 06 (07) ◽  
pp. 543-551 ◽  
Author(s):  
R.E. KARLSEN ◽  
M.D. SCADRON

We show that K→ππ and charmed [Formula: see text] decays can be understood using chiral symmetry and a meson loop model to simulate first order weak decays driven by the heavy-W vector boson.

2020 ◽  
Vol 2020 (12) ◽  
Author(s):  
Francesco Bigazzi ◽  
Alessio Caddeo ◽  
Aldo L. Cotrone ◽  
Angel Paredes

Abstract Using the holographic correspondence as a tool, we study the dynamics of first-order phase transitions in strongly coupled gauge theories at finite temperature. Considering an evolution from the large to the small temperature phase, we compute the nucleation rate of bubbles of true vacuum in the metastable phase. For this purpose, we find the relevant configurations (bounces) interpolating between the vacua and we compute the related effective actions. We start by revisiting the compact Randall-Sundrum model at high temperature. Using holographic renormalization, we compute the derivative term in the effective bounce action, that was missing in the literature. Then, we address the full problem within the top-down Witten-Sakai-Sugimoto model. It displays both a confinement/deconfinement and a chiral symmetry breaking/restoration phase transition which, depending on the model parameters, can happen at different critical temperatures. For the confinement/deconfinement case we perform the numerical analysis of an effective description of the transition and also provide analytic expressions using thick and thin wall approximations. For the chiral symmetry transition, we implement a variational approach that allows us to address the challenging non-linear problem stemming from the Dirac-Born-Infeld action.


2022 ◽  
Vol 258 ◽  
pp. 10006
Author(s):  
Juan L. Mañes ◽  
Eugenio Megías ◽  
Manuel Valle ◽  
Miguel Á. Vázquez-Mozo

We study the constitutive relations of a chiral hadronic fluid in presence of non-Abelian’t Hooft anomalies. Analytical expressions for the covariant currents are obtained at first order in derivatives in the chiral symmetric phase, for both two and three quark flavors in the presence of chiral imbalance. We also investigate the constitutive relations after chiral symmetry breaking at the leading order.


1998 ◽  
Vol 13 (11) ◽  
pp. 1847-1880 ◽  
Author(s):  
LUIS ÁLVAREZ-GAUMÉ ◽  
MARCOS MARIÑO ◽  
FREDERIC ZAMORA

We analyze the vacuum structure of N=2, SU(2) QCD with massive quark hypermultiplets, once supersymmetry is softly broken down to N=0 with dilaton and mass spurions. We give general expressions for the low energy couplings of the effective potential in terms of elliptic functions to have a complete numerical control of the model. We study in detail the possible phases of the theories with Nf=1,2 flavors for different values of the bare quark masses and the supersymmetry breaking parameters and we find a rich structure of first order phase transitions. The chiral symmetry breaking pattern of the Nf=2 theory is considered, and we obtain the pion Lagrangian for this model up to two derivatives. Exact expressions are given for the pion mass and Fπ in terms of the magnetic monopole description of chiral symmetry breaking.


2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Shinichiro Akiyama ◽  
Yoshinobu Kuramashi ◽  
Takumi Yamashita ◽  
Yusuke Yoshimura

Abstract We analyze the chiral phase transition of the Nambu-Jona-Lasinio model in the cold and dense region on the lattice, developing the Grassmann version of the anisotropic tensor renormalization group algorithm. The model is formulated with the Kogut-Susskind fermion action. We use the chiral condensate as an order parameter to investigate the restoration of the chiral symmetry. The first-order chiral phase transition is clearly observed in the dense region at vanishing temperature with μ/T ∼ O(103) on a large volume of V = 10244. We also present the results for the equation of state.


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