Spontaneous Parity Violation Research Articles

Possibility of Spontaneous Parity Violation in Hot QCD

We suggest that for QCD in the limit of a large number of colors, N, the axial U(1) symmetry of massless quarks is effectively restored at the deconfining=chiral phase transition. If the deconfining transition is of second order, then the chiral transition is weakly first order. In this case, metastable states in which parity is spontaneously broken appear at temperatures below the phase transition. The production of these metastable states would have dramatic signatures, including enhanced production of eta and eta' mesons, which can decay through parity violating decay processes such as eta -> pi^0 pi^0, and global parity odd asymmetries for charged pions. Using a nonlinear sigma model, in QCD these metastable states only appear rather near the phase transition.

Left-right symmetric and vectorlike models through P invariance of the Lagrangian.

We take two sets of fields, one having even intrinsic parities, the other having odd intrinsic parities, where the gauge fields in both sets transform in the same way under charge conjugation. We construct a Lagrangian out of these fields which is invariant under P. We show that, with an additional discrete symmetry the simplest implementation of the scheme is the left-right symmetric model. We also show that vectorlike models with spontaneous parity violation and with the correct neutral current content are possible in this scheme.

Theory of Developed Turbulence: Principle of Maximal Randomness and Spontaneous Parity Violation

A set of self-consistent equations in one-loop approximation in a statistical model of fully developed homogeneous isotropic turbulence, which is based on the principle of maximal randomness of the velocity field with a given energy spectral flux, is obtained. These equations do not possess both infrared and ultraviolet divergences near the Kolmogorov values of indices. The formal solution found of the system of equations yields Kolmogorov exponents, but this solution leads to negative Kolmogorov constant C k and negative viscosity. It has been shown, that the turbulent fluid becomes stable if spontaneous parity violation is achieved. Namely, the solution with the Kolmogorov indices and additional helical terms (which lead to positive both C k and effective viscosity) exists. This solution predicts a large, closed to limit value, helical coefficient Θ in inertial range. The relationship obtained between C k and e confirms this conclusion for the experimental value of C k .

Exact and broken symmetries in a hydrodynamical description of chiral spin states

Following the procedure recently proposed by Wiegmann, we improve his analysis and derive a complete effective Lagrangian describing long-wavelength fluctuations around hypothetical three-dimensional (3D) and 2D chiral states of Heisenberg spin systems. We study realizations of the previously proposed high symmetry group of the continuous theory [SO(3,1)[times]SU(2)[times]U(1) in 3D and SO(2,1)[times]U[sub [ital c]](1)[times]U[sub [ital s]](1) in 2D] and observe that, in general, Lorentz symmetry is broken already in the bare Lagrangian, although it could be restored after a renormalization. In contrast to the conjectures made by Wiegmann, an additional non-Abelian SU(2) gauge symmetry expected in 3D (and its Abelian counterpart in 2D) are, in fact destroyed due to a spontaneous parity violation in chiral ground states.

Spontaneous symmetry breaking versus spontaneous parity violation

We discuss the possibility of spontaneous parity violation in three-dimensional minkowskian and euclidean gauge theories with scalar fields. In perturbation theory, it is found that parity can be broken spontaneously only in the phase with restored gauge invariance, but is unbroken if the scalars have vacuum expectation values. We note that the spontaneous parity violation in the euclidean case may be related to the breaking of translational invariance. Implications of these results for high temperature gauge theories and cosmology are considered.

Spontaneous parity violation in a supersymmetric nonlinear σ-model in 2+1 dimensions

A supersymmetric nonlinear σ-model in 2+1 dimensions is constructed. The renormalization of the coupling constant makes the model finite to leading order in the 1 N expansion. Mass generation and supersymmetric bound states occur as consequences of spontaneous violation of parity.

Parity-doubling chiral solitons with vector mesons

We argue the presence of new classical solutions with spontaneous parity violation in chiral soliton models coupled with vector fields. Using a variational method, we find that these solutions become stable minima when a coupling of a fourth-order stabilizing term is larger than a critical value. These form an almost degenerate parity doublet via tunneling effects at the semi-classical level.

Numerical evidence for a parity-violating phase in lattice QCD with Wilson fermions

The existence of the parity violating phase in lattice QCD with Wilson fermions in the quenched approximation is examined. Numerical evidence for spontaneous parity violation at K> K c is presented.

Spontaneous parity violation and Higgs-meson masses in a composite model for leptons, quarks, and Higgs mesons.

Parity violation in the left-right-symmetric gauge model is naturally understood in a composite model by imposing the consistency of the model, that is, stability of the Higgs potential and positivity of squared masses of observable mesons. Two quite different types of solutions, which are respectively characterized with massless neutrinos and nonzero-mass neutrinos, are left as realistic solutions and the choice of one of them is determined by the sign of one coupling constant in the Higgs potential. The model predicts some Higgs mesons with masses of the order of ${M}_{{W}_{L}}$ (\ensuremath{\sim}100 GeV), one of which will be observed in the charged lepton-antilepton pair decays, such as the ${\ensuremath{\tau}}^{\mathrm{\ensuremath{-}}}$${\ensuremath{\tau}}^{+}$ mode.

Derivation of very tiny masses of neutrinos in the left-right symmetric gauge model

Very tiny mass values of neutrinos are derived in the left-right symmetric gauge model with spontaneous parity violation. In our scheme the Dirac mass terms of neutrinos vanish in the tree level, but they are induced in higher order and proportional to the charged-lepton mass terms. The relation, m ν l ⋍ G 0m l 2 m WR , with G 0⪅10 −13 for the three generations, is derived. We also discuss the model where the mixings among the lepton generations vanish.

Neutrino masses and mixings in gauge models with spontaneous parity violation

Unified electroweak gauge theories based on the gauge group $\mathrm{SU}{(2)}_{L}\ifmmode\times\else\texttimes\fi{}\mathrm{SU}{(2)}_{R}\ifmmode\times\else\texttimes\fi{}\mathrm{U}{(1)}_{B\ensuremath{-}L}$, in which the breakdown of parity invariance is spontaneous, lead most naturally to a massive neutrino. Assuming the neutrino to be a Majorana particle, we show that smallness of its mass can be understood as a result of the observed maximality of parity violation in low-energy weak interactions. This result is shown to be independent of the number of generations and unaffected by renormalization effects. Phenomenological consequences of this model at low energies are studied. Observation of neutrinoless double-$\ensuremath{\beta}$ decay will provide a crucial test of this class of models. Implications for rare decays such as $\ensuremath{\mu}\ensuremath{\rightarrow}e\ensuremath{\gamma}$, $\ensuremath{\mu}\ensuremath{\rightarrow}\mathrm{ee}\overline{e}$, etc. are also noted. It is pointed out that in the realm of neutral-current phenomena, departure from the predictions of the standard model for polarized-electron-hadron scattering, forward-backward asymmetry in ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$, and neutrino interactions has a universal character and may be therefore used as a test of the model.

New origin ofCPviolation in SU(2) × U(1) gauge models

It is proposed that $\mathrm{CP}$ violation originates in a Yukawa interaction of a single, charged scalar meson, not a Higgs particle, with bilinear forms which contain a light quark and a heavy quark. These Yukawa couplings are the only source of $\mathrm{CP}$ violation and the only direct interaction between light quarks and heavy quarks. Detailed results are worked out for a local SU(2) \ifmmode\times\else\texttimes\fi{} U(1) gauge model with spontaneous parity violation. It is required that $\ensuremath{\Delta}S=2$ $\mathrm{CP}$-conserving processes are dominated by $W$ exchange and $\ensuremath{\Delta}S=2$ $\mathrm{CP}$-violating process are dominated by exchange of the charged scalar meson, called $\ensuremath{\chi}$. The $\ensuremath{\Delta}S=1$ $\mathrm{CP}$ violations and electric dipole of moments of quarks are shown to be extremely small for any values of the $\mathrm{CP}$-violating phases of the $\ensuremath{\chi}$ Yukawa coupling constants. Quasistable, heavy hadrons are a special feature of the model presented, and their properties are summarized. Distinctive features of such hadrons are long lifetimes (greater than ${10}^{\ensuremath{-}9}$ sec), absence of nonleptonic decay modes with only light hadrons, and the likelihood of large $\mathrm{CP}$-violation effects as compared to those of the $K$-meson system.