scholarly journals LOW LYING SCALAR RESONANCES AND CHIRAL SYMMETRY

2008 ◽  
Vol 23 (27n30) ◽  
pp. 2218-2225 ◽  
Author(s):  
HANQING ZHENG
Keyword(s):  
Chiral Symmetry ◽  
Theoretical Studies ◽  
Goldstone Bosons ◽  
Scalar Resonances ◽  
Chiral Partner

Current theoretical studies on the σ and κ resonances are reviewed. It is emphasized that all evidences accumulated so far are consistent with the picture that the σ meson is the chiral partner of the Nambu–Goldstone bosons in a linear realization of chiral symmetry.

scholarly journals EFFECTIVE COUPLINGS OF DYNAMICAL NAMBU–GOLDSTONE BOSONS WITH ELEMENTARY FERMIONS

2000 ◽  
Vol 15 (10) ◽  
pp. 709-721
Author(s):  
TAKAYUKI MATSUKI ◽  
MASASHI SHIOTANI
Keyword(s):  
Gauge Theory ◽  
Chiral Symmetry ◽  
Effective Action ◽  
Scalar Fields ◽  
Spontaneous Breakdown ◽  
Decay Constants ◽  
Goldstone Bosons

Assuming dynamical spontaneous breakdown of chiral symmetry for massless gauge theory without scalar fields, we find a method to construct an effective action of the dynamical Nambu–Goldstone bosons and elementary fermions by using auxiliary fields. Here dynamical particles are assumed to be composed of elementary fermions. Various quantities including decay constants are calculated from this effective action.

ON THE PHENOMENOLOGICAL σ MODELS

1994 ◽  
Vol 09 (20) ◽  
pp. 3669-3681 ◽  
Author(s):  
N.N. ACHASOV ◽  
G.N. SHESTAKOV
Keyword(s):  
Chiral Symmetry ◽  
Scalar Meson ◽  
Phenomenological Description ◽  
Decay Widths ◽  
Scalar Resonances

The question of the phenomenological description of the broad scalar resonances compatible with chiral symmetry and unitarity is discussed within the linear σ model. It is shown that the naive consideration of the decay widths in the scalar-meson propagators is not an adequate approximation for the physical amplitudes. In this connection Refs. 8–10 are critically discussed. In particular, the K+→ π+π−e+ν and Ks→ππ decays are treated within the linear σ model with due regard for the unitarity.

scholarly journals Degeneracy Patterns of Chiral Companions at Finite Temperature

Symmetry ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1400
Author(s):  
Juan M. Torres-Rincon
Keyword(s):  
Chiral Symmetry ◽  
Nuclear Physics ◽  
Degrees Of Freedom ◽  
Sigma Model ◽  
Smooth Transition ◽  
Linear Sigma Model ◽  
Spontaneous Breaking ◽  
Low Energies ◽  
Effective Theories ◽  
Chiral Partner

Chiral symmetry represents a fundamental concept lying at the core of particle and nuclear physics. Its spontaneous breaking in vacuum can be exploited to distinguish chiral hadronic partners, whose masses differ. In fact, the features of this breaking serve as guiding principles for the construction of effective approaches of QCD at low energies, e.g., the chiral perturbation theory, the linear sigma model, the (Polyakov)–Nambu–Jona-Lasinio model, etc. At high temperatures/densities chiral symmetry can be restored bringing the chiral partners to be nearly degenerated in mass. At vanishing baryochemical potential, such restoration follows a smooth transition, and the chiral companions reach this degeneration above the transition temperature. In this work I review how different realizations of chiral partner degeneracy arise in different effective theories/models of QCD. I distinguish the cases where the chiral states are either fundamental degrees of freedom or (dynamically-generated) composed states. In particular, I discuss the intriguing case in which chiral symmetry restoration involves more than two chiral partners, recently addressed in the literature.

HEAVY AXION ON SARK BRIDGE BETWEEN HIGGS AND TECHNICOLOR MODELS

1991 ◽  
Vol 06 (17) ◽  
pp. 1589-1596
Author(s):  
P. H. FRAMPTON ◽  
T. YANAGIDA
Keyword(s):  
Symmetry Breaking ◽  
Chiral Symmetry ◽  
Chiral Symmetry Breaking ◽  
General Picture ◽  
Goldstone Bosons ◽  
Technicolor Model

It is shown how imposition of Peccei–Quinn symmetry leads to a heavy axion and strong constraints in the sark model. The axion and sark masses are derived. Analysis of chiral symmetry breaking leads to mass formulae for pseudo-Goldstone bosons; the lightest is between 44 and 125 GeV. A general picture which bridges between the sark model and a technicolor model, in terms of a new angle, is proposed.

scholarly journals Alternative Scheme of Spontaneous Chiral Symmetry Breaking

1986 ◽  
Vol 39 (3) ◽  
pp. 347 ◽  
Author(s):  
GA Christos
Keyword(s):  
Symmetry Breaking ◽  
Chiral Symmetry ◽  
Quark Mass ◽  
Chiral Symmetry Breaking ◽  
Alternative Scheme ◽  
Goldstone Bosons ◽  
Spontaneous Chiral Symmetry Breaking ◽  
Mass Ratios ◽  
Usual Scheme

We develop an alternative scheme of spontaneous chiral symmetry breaking which is characterized by four-quark condensates instead of (7jq),*O. In this scheme the Nambu-Goldstone bosons acquire a mass squared - m~uark' in comparison with mquark in the usual scheme. The quark mass ratios and the parameters of the scheme are determined by an application to the pseudoscalar nonet spectrum (including 'lT0_'Yj_'Yj' mixing). The decays Iji -+('lT0 , 'Yj, 'Yj}y and Iji' -+ 1ji('lT0 , 'Yj) are also considered. The results do not promote the alternative scheme.

scholarly journals Mirror versus naive assignment in chiral models for the nucleon

2014 ◽  
Vol 29 (17) ◽  
pp. 1450098 ◽  
Author(s):  
Susanna Gallas ◽  
Francesco Giacosa
Keyword(s):  
Chiral Symmetry ◽  
Scattering Length ◽  
Low Energy ◽  
Chiral Model ◽  
Good Agreement ◽  
Chiral Partner

In the framework of chiral model(s) based on the linear realization of chiral symmetry, we investigate the low-energy phenomenological properties of the nucleon and its chiral partner (identified with either N(1535) or N(1650)) in the naive assignment and compare the results with the ones obtained in the mirror assignment. We find that, within the naive assignment, we are not able to reproduce the experimental value of the isospin-odd scattering length, while the mirror assignment is in good agreement with it for both choices N(1535) and N(1650). The isospin-even scattering length is not yet conclusive in either assignment because it depends crucially on the poorly known scalar mesonic sector. The decay with ΓN(1535)→Nη turns out to be far too small in both the naive and mirror assignments, while ΓN(1650)→Nη is described correctly by both of them. In conclusion, the mirror assignment with N(1650) as the chiral partner of the nucleon is the favored configuration.

scholarly journals QUARK MASS RATIOS AND MASS SPLIT OF π0-π±INChPTWITH THE DIFFERENCE OF QUARK CONDENSATES CONSIDERED

2008 ◽  
Vol 23 (22) ◽  
pp. 3493-3507
Author(s):  
XIAOYA LI ◽  
BIN WANG ◽  
XIAOZHAO CHEN ◽  
XIAOFU LÜ
Keyword(s):  
Chiral Symmetry ◽  
Pseudoscalar Meson ◽  
Quark Mass ◽  
Quark Condensate ◽  
Breaking Effect ◽  
Goldstone Bosons ◽  
Effective Lagrangian ◽  
Pseudoscalar Mesons ◽  
Mass Ratios ◽  
The Difference

The chiral effective Lagrangian for pseudoscalar meson nonet including eight Goldstone bosons and a SU (3) singlet η0is constructed with the breaking effect of chiral symmetry in both quark condensate and quark mass differences taken into account. The [Formula: see text] mixing is discussed. By solving the mass equations of pseudoscalar mesons, the quark mass ratios are obtained and the quark condensate ratios are constrained in ranges. The mass split of π0-π±is discussed.

scholarly journals STATUS OF CHIRAL DOUBLERS OF HEAVY-LIGHT HADRONS IN LIGHT OF RECENT BABAR, CLEO, BELLE AND SELEX Ds STATES

2005 ◽  
Vol 20 (02n03) ◽  
pp. 229-239 ◽  
Author(s):  
MACIEJ A. NOWAK
Keyword(s):  
Heavy Quark ◽  
Chiral Symmetry ◽  
Main Idea ◽  
Spin Symmetry ◽  
Spin Parity ◽  
Quark Spin ◽  
New States ◽  
Heavy Quark Spin Symmetry ◽  
Effective Theories ◽  
Chiral Partner

We explain the main idea of the chiral doublers scenario, originating from simultaneous constraints of chiral symmetry and of heavy quark spin symmetry on effective theories of heavy-light hadrons. In particular we discuss chiral doublers for mesons, chiral doublers for excited mesons, chiral doublers for baryons and chiral doublers for excited baryons. We point out the arguments why new states Ds(2317) and Ds(2457) might be viewed as chiral doublers of Ds and [Formula: see text]. Then we comment on non-strange mesons D0(2308) and D′1(2427) observed by Belle and Focus, and on Θc(3099) signal observed by H1. Finally, we point out that very recent discovery by SELEX of Ds(2632), if confirmed by other experiments and if spin-parity of this state is 1-, may be interpreted as a signal for chiral doubler of Ds1(2536). Such an identification implies another narrow, spin-parity 2-Ds state ca 37 MeV above the new 1-, corresponding to chiral partner of Ds2.

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