scholarly journals Quark masses and chiral symmetry

1995 ◽  
Vol 52 (5) ◽  
pp. 2951-2959 ◽  
Author(s):  
Michael Creutz
Keyword(s):  
Chiral Symmetry ◽  
Quark Masses

scholarly journals Light quark masses in quenched QCD with exact chiral symmetry

2002 ◽  
Vol 538 (3-4) ◽  
pp. 298-300 ◽  
Author(s):  
Ting-Wai Chiu ◽  
Tung-Han Hsieh
Keyword(s):  
Chiral Symmetry ◽  
Light Quark ◽  
Quark Masses

NEUTRAL PION PHOTOPRODUCTION ON THE PROTON AND THE CLOUDY-BAG MODEL

1992 ◽  
Vol 07 (21) ◽  
pp. 5231-5244
Author(s):  
A.N. TABACHENKO
Keyword(s):  
Symmetry Breaking ◽  
Chiral Symmetry ◽  
Electric Dipole ◽  
Neutral Pion ◽  
Chiral Symmetry Breaking ◽  
Pion Photoproduction ◽  
Additional Contribution ◽  
Bag Model ◽  
Neutral Pions ◽  
Quark Masses

In the cloudy-bag model, the value of the electric dipole amplitude of the photoproduction of neutral pions off protons at threshold connected with the additional contribution from the chiral symmetry breaking interaction is evaluated. If this additional contribution is included in the amplitude of the photoproduction of neutral pions off protons at threshold, the discrepancy between the LET predictions and the measured value of the electric dipole amplitude [Formula: see text] can be resolved for the values of quark masses and bag radii which are close to the generally used values.

scholarly journals CHIRAL PERTURBATION THEORY WITH NUCLEONS

1992 ◽  
Vol 01 (03) ◽  
pp. 561-601 ◽  
Author(s):  
Ulf-G. Meißner
Keyword(s):  
Perturbation Theory ◽  
Chiral Symmetry ◽  
Chiral Perturbation Theory ◽  
Chiral Limit ◽  
Nuclear Forces ◽  
Chiral Perturbation ◽  
Chiral Structure ◽  
Quark Masses ◽  
Alternative Approach ◽  
Working Out

I review the constraints posed on the interactions of pions, nucleons and photons by the spontaneously broken chiral symmetry of QCD. The framework to perform these calculations, chiral perturbation theory, is briefly discussed in the meson sector. The method is a simultaneous expansion of the Greens functions in powers of external momenta and quark masses around the massless case, the chiral limit. To perform this expansion, use is made of a phenomenological Lagrangian which encodes the Ward–identities and pertinent symmetries of QCD. The concept of chiral power counting is introduced. The main part of the lectures consists in describing how to include baryons (nucleons) and how the chiral structure is modified by the fact that the nucleon mass in the chiral limit does not vanish. Particular emphasis is put on working out applications to show the strengths and limitations of the method. Some processes which are discussed are threshold photopion production, low-energy Compton scattering off nucleons, πN scattering and the σ–term. The implications of the broken chiral symmetry on the nuclear forces are briefly described. An alternative approach, in which the baryons are treated as very heavy fields, is touched upon.

scholarly journals NEW ANGLE ON THE STRONG CP AND CHIRAL SYMMETRY PROBLEMS FROM A ROTATING MASS MATRIX

2009 ◽  
Vol 24 (01) ◽  
pp. 101-112 ◽  
Author(s):  
JOSÉ BORDES ◽  
HONG-MO CHAN ◽  
TSOU SHEUNG TSUN
Keyword(s):  
Chiral Symmetry ◽  
Chiral Symmetry Breaking ◽  
Mass Matrix ◽  
Energy Scale ◽  
Fermion Mass ◽  
Mass Hierarchy ◽  
Quark Masses ◽  
Chiral Transformation ◽  
The Masses ◽  
Fermion Mass Matrix

It is shown that when the mass matrix changes in orientation (i.e. rotates) in generation space for a changing energy scale, the masses of the lower generations are not given just by its eigenvalues. In particular, these masses need not be zero even when the eigenvalues are zero. In that case, the strong CP problem can be avoided by removing the unwanted θ term by a chiral transformation not in contradiction with the nonvanishing quark masses experimentally observed. Similarly, a rotating mass matrix may shed new light on the problem of chiral symmetry breaking. That the fermion mass matrix may so rotate with the scale has been suggested before as a possible explanation for up–down fermion mixing and fermion mass hierarchy, giving results in good agreement with experiment.

Chiral Symmetry

2019 ◽  
pp. 217-230
Author(s):  
Michael E. Peskin
Keyword(s):  
Symmetry Breaking ◽  
Spontaneous Symmetry Breaking ◽  
Chiral Symmetry ◽  
Goldstone Boson ◽  
Spontaneous Breaking ◽  
Quark Masses ◽  
Zero Mass ◽  
K Mesons ◽  
The Masses

This chapter introduces chiral symmetry, the extra symmetry that QCD acquires when the masses of quarks are set to zero. It introduces the concept of spontaneous symmetry breaking and explains the spontaneous breaking of chiral symmetry in QCD. It introduces the concept of a Goldstone boson, a particle that has zero mass as the result of spontaneous symmetry breaking, and explains how this concept explains properties of the pi and K mesons and allows us to determine the underlying values of the quark masses.

Dynamical chiral-symmetry breaking and determination of the quark masses

1988 ◽  
Vol 38 (1) ◽  
pp. 238-278 ◽  
Author(s):  
A. Barducci ◽  
R. Casalbuoni ◽  
S. De Curtis ◽  
D. Dominici ◽  
R. Gatto
Keyword(s):  
Symmetry Breaking ◽  
Chiral Symmetry ◽  
Chiral Symmetry Breaking ◽  
Dynamical Chiral Symmetry Breaking ◽  
Quark Masses
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