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S. Ying

Publications and source records attributed to S. Ying.

16 recordsLinked to original sources
arXiv2000

Space--Time Symmetry, CPT and Mirror Fermions

The motivations for the construction of an 8-component representation of fermion fields based on a two dimensional representation of time reversal transformation and CPT invariance are discussed. Some of the elementary properties of the quantum field theory in the 8-component representation are studied. It includes the space-time and charge conjugation symmetries, the implementation of a reality condition, the construction of interaction theories, the field theoretical imaginary- and real-time approach to thermodynamics of fermionic systems, the quantization of fermion fields, their particle content and the Feynman rules for perturbation theories. It is shown that in the new presentation, a CPT violation can be formulated in principle. The construction of interaction theories in the 8-component theory for fermions is shown to be constrained by the CPT invariance. The short distance behavior and relativistic covariance are studied. In the path integral representation of the thermodynamical potential, the conventional imaginary-time approach is shown to be smoothly connected to a real-time thermal field theory in the 8-component representation for fermion fields without any additional subtraction of infinities. The metastability at zero density and the nature of the spontaneous CP violation in color superconducting phases of strong interaction ground states are clarified.

hep-th↗
arXiv2000

Color superconductivity and its electromagnetic manifestation

A collection of the physical observables, related to the electromagnetic properties of a nucleon, to investigate the non--perturbative quantum fluctuations in the strong interaction vacuum state under the influence of at least one close by (in energy density) color superconducting phase found in several QCD motivated model calculations, are studied. It is shown that the spontaneous breaking of the electromagnetic gauge symmetry in the color superconducting phase of strong interaction can result in relatively clean signals in high energy processes, especially in the semi-leptonic deep inelastic scattering ones, due to a kind of electromagnetic induced strong interaction. A new type of mechanism, which is a generalization of the Higgs one, through which the local electromagnetic gauge symmetry is spontaneously broken by a spontaneous breaking of the global baryon (nucleon) number conservation, is revealed. A model independent assessment of the question of how far is the color superconducting phase of the strong interaction from its vacuum phase is made by studying currently available experimental data on the electromagnetic responses of a nucleon at high energies. It is shown that based on our current knowledge about a nucleon, it is quite likely that there is at least one color superconducting phase for the strong interaction that is close enough to the vacuum state so that its effects can even be seen in high energy processes besides heavy ion collisions.

hep-ph↗
arXiv2000

On the Nucleon Stability and Sigma_N Term Puzzles

A stable soliton configuration for a nucleon emerges when the nucleon stability and $Σ_N$ term discrepancy problems are studied semi-quantitatively within a local theory developed recently. The approach developed here goes beyond the mean field or Hartree-Fock approximation by taking into account of the non-perturbative wave function renormalization in a way that is consistent with the chiral Ward-Takahashi identities of QCD. The stability condition for a nucleon and the recently extracted nucleon $Σ_N$ term are used to estimate the radius of the soliton. It is found that 0.67 fm $\le R \le$ 0.78 fm. A new mechanism for the stability of a nucleon is proposed. The discrepancy between the nucleon $Σ_N$ term extracted from pion--nucleon scattering data and the one from baryonic spectra is resolved by assuming the existence of a metastable virtual color superconducting phase for the strong interaction vacuum. Under such a scenario, the difference between the energy density of the chiral symmetry breaking phase and the metastable color superconducting phase is found to be 0.41 GeV/fm$^3$ $\le Δε\le $ 0.85 GeV/fm$^3$.

hep-ph↗
arXiv2000

On an Extended PCAC Relationship

We explore a consistent way to extend the partially conserved axial vector current (PCAC) relationship and corresponding current algebra results in two strongly correlated directions: 1) towards a search for a set of systematic rules for the establishment of PCAC related relationships in a finite low momentum transfer region and for the extrapolation of the momentum transfer $q^2$ to zero when deriving the low energy PCAC results that can be compared to experimental data and 2) towards taking into account, besides the conventional one, the only other possibility of the spontaneous chiral symmetry breaking, $SU(2)_L\times SU(2)_R \to SU(2)_V$, inside a baryonic system by a condensation (in the sense to be specified in the paper) of diquarks. The paper includes investigations of a chiral Ward--Takahashi identity, the explicit chiral symmetry breaking by a finite current quark mass, the modification of the PCAC relationship and its consequences. It is shown that the signals for a hypothetical diquark condensation inside a nucleon and nucleus is observable in high precision experiments despite the fact that they may evade most of the current observations. We briefly discuss how diquark condensation could provide an answer to the question of where about of pions and quark number in a nucleon and a nucleus, which is raised in explaining puzzles in polarized pion nucleus scattering, violation of Gottfried sum rule and EMC effects.

nucl-th↗
arXiv2000

Virtual Color Superconductivity and Nucleon Structure

The observed electromagnetic (EM) properties of a nucleon at high energy are studied to search for a possible metastable color superconducting phase, called a virtual phase, that has an energy density close to the true ground state of the vacuum. The discussion is based on a mechanism of spontaneous partial breaking of the EM U(1) gauge symmetry inside a color superconductor. Favorable evidences for such a scenario are found.

hep-ph↗
arXiv2000

Local Finite Density Theory, Statistical Blocking and Color Superconductivity

The motivation for the development of a local finite density theory is discussed. One of the problems related to an instability in the baryon number fluctuation of the chiral symmetry breaking phase of the quark system in the local theory is shown to exist. Such an instability problem is removed by taking into account the statistical blocking effects for the quark propagator, which depends on a macroscopic {\em statistical blocking parameter} $ε$. This new frame work is then applied to study color superconducting phase of the light quark system.

hep-ph↗
arXiv1999

Statistical Gauge Theory for Relativistic Finite Density Problems

A relativistic quantum field theory is presented for finite density problems based on the principle of locality. It is found that, in addition to the conventional ones, a local approach to the relativistic quantum field theories at both zero and finite density consistent with the violation of Bell like inequalities should contain, and provide solutions to at least three additional problems, namely, 1) the statistical gauge invariance 2) the dark components of the local observables and 3) the fermion statistical blocking effects, base upon an asymptotic non-thermo ensemble. An application to models are presented to show the importance of the discussions.

hep-th↗
arXiv1999

On the Local Finite Density Relativistic Quantum Field Theories

It is found that, in addition to the conventional ones, a local approach to the relativistic quantum field theories at both zero and finite density consistent with the violation of Bell like inequalities should contain, and provide solutions to at least three additional problems, namely, 1) the statistical gauge invariance 2) the dark components of the local observables and 3) the fermion statistical block effects, base upon an asymptotic non-thermo ensemble. An application to models are presented to show the relevance of the discussions.

hep-th↗
arXiv1998

Gerasimov-Drell-Hearn sum rule and nucleon structure

A modification of the Gerasimov--Drell--Hearn sum rule suggested by the current experimental data is presented. Within the conventional theoretical framework, we find it necessary to consider the possibility of the presence of a localized region inside a nucleon, in which the electromagnetic (EM) gauge symmetry is spontaneous broken down, if the constraints of the gauge invariance, Lorentz invariance and the assumption of the commutativity of the EM charge density operator at equal-time are considered. We also discuss the propagation of a virtual photon inside a nucleon under such a scenario. A comment on some of the recent model independent works on the same subject is provided.

hep-ph↗
arXiv1997

The Quantum Aspects of Relativistic Fermion Systems with Particle Condensation

A consistent local approach to the study of interacting relativistic fermion systems with a condensation of bare particles in its ground or vacuum state, which may has a finite matter density, is developed. The attention is payed to some of the not so well explored quantum aspects that survive the thermodynamic limit. A 4-vector local field, called the primary statistical gauge field, and a statistical blocking parameter are introduced for a consistent treatment of the problem. The effects of random fluctuations of the fields on local observables are discussed. It is found that quasiparticle contributions are not sufficient to saturate local observables. The property of the primary statistical gauge field are discussed in some detail. Two models for the strong interaction are then introduced and studied using the general framework developed. Four possible phases for these models are found. The possibility of spontaneous CP violation and local fermion creation in two of the four phases is revealed. The implications of the finding on our understanding of some of the strong interaction processes are discussed.

hep-th↗
arXiv1997

Quasiparticles and the quantum fluctuations of local observables

The role that quasiparticles play in a strong interaction system with spontaneous symmetry breaking is examined. We find, using a non- perturbative cluster decomposition method, that the quasiparticles do not saturate the physical local observables at small distances. The fermion number density serves as a clearcut example. A component due to localized random quantum fluctuations of the order parameter(s) in the vacuum state and the contributions of ``quasiparticles'' corresponding to other local minima of the effective potential is needed. At large distances, the ordinary quasiparticle picture emerges in the response of the system to classical background fields but the above mentioned component acts as a source for them.

hep-ph↗
arXiv1996

A path integration approach to relativistic finite density problems and its particle content

A path integration formulation for the finite density and temperature problems is shown to be consistent with the thermodynamics using an 8 component ``real'' representation for the fermion fields by applying it to a free fermion system. A relativistic quantum field theory is shown to be smoothly approached at zero temperature by a real-time thermal field theory so derived even at a finite density. The analysis leads to a new representation for the fermion fields which is shown to be inequivalent to the conventional 4 component theory at the quantum level by having a mirror universe with observable effects and to be better behaved at short distances.

hep-th↗
arXiv1996

Possible Phases in Strong Interaction Vacuum

A study of the possible vacuum phases in a strongly interacting two flavor light quark system is presented. Four possible phases are found with some of their properties presented. The possible existence of localized U(1) EM symmetry breaking phases inside a nucleon and excited hadrons is investigated by showing the potential of solving three selected current ``puzzles'' in experimental obervations if such a possibility is taken into account. Base on these results, the potential of producing these phases in heavy ion collisions is speculated.

hep-ph↗
arXiv1995

Extended PCAC Relation

We explore a consistent way to extend the partially conserved axial vector current (PCAC) relation and corresponding current algebra results. The paper includes investigations of a chiral Ward-Takahashi identity, the explicit chiral symmetry breaking by a finite current quark mass, the modifica- tion of the PCAC relation and its consequences. Two explicit relations between the nucleon axial vector form factor $g_A(q^2)$, pseudo-scalar form factor $ g_P(q^2)$ and the pion-nucleon coupling constant $g_{πNN}(q^2)$ is obtained. One of the relation is confirmed, within the experimental error, by observation in the $0<-q^2 <0.2$ $\mbox{GeV}^2$ region. The other one, which relates $g_A(q^2)$ and $f_π(q^2) g_{πNN}(q^2)$ is studied by using known empirical facts and dispersion relation. Thoeretical uncertainties are evaluated. Certain inconsistencies, which is in favor of the introduction of diquark condensation, is discovered. We briefly discuss how diquark condensation could provide an answer to the question of where about of the quark numbers in a nucleon and a nucleus, which is raised in explaining puzzles observed in the violation of Gottfried sum rule and EMC effects.

hep-ph↗
arXiv1994

Time Reversal Invariance in the beta-Decays of A = 8 Nuclei

We examine time reversal invariance in the beta-decays of 8B(2+) and 8Li(2+) to 8Be(2+) in detail, with particular attention to final state interactions of the two alpha particles from the decay of 8Be, and of the electron (positron) with the daughter nucleus. A R-matrix formulation is used, with the initial state described by a shell model. The R-matrix parameters are obtained by fitting the alpha-αscattering phase shifts and allowed beta-decay rates. Because the nuclear final state interaction effects on the time reversal test come from second forbidden beta-decays, they are small and can be minimized by a suitable choice of kinematic conditions. The e(+/-)-nucleus Coulomb interaction induced T-violation effects depend on the first forbidden operators.

nucl-th↗