The flavor universality of some mass splittings in hadrons

The approximate chiral invariance of the two-flavor (QCD) is known to be spontaneously broken. This effect explains the relatively small pion mass and, as is widely believed, the mass splittings of would-be chiral partners — the hadrons of equal spin but opposite parity lying in one multiplet of the chiral symmetry. We present experimental evidences that in reality such mass splittings in the meson sector seem to be approximately flavor-independent in all cases where they can be tested experimentally — the spin 0 and 1. In addition, a partial flavor independence holds for spin-1/2 baryons (namely among states in which at least one of the quark is not u or d one). This property allow to predict masses and quantum numbers for 10 new hadrons. The given flavor-independence, if confirmed for higher spins, hints at the existence of universal scale Λ strong ~300 MeV in the strong interactions which, in contrast to Λ QCD , is flavor and scheme independent. Some manifestations of Λ strong are discussed.

Suppression of superconductivity by inhomogeneous chiral condensation in the NJL2 model

We investigate the possibility of spatially inhomogeneous chiral and Cooper, or superconducting, pairing in the (1+1)-dimensional model by Chodos et al. [Phys. Rev. D 61, 045011 (2000)] generalized to continuous chiral invariance. The consideration is performed at nonzero values of temperature T and quark number chemical potential μ. In the framework of the Fulde–Ferrel inhomogeneity ansatz for chiral and Cooper condensates, we show that if G1>G2, where G1 and G2 are the coupling constants in the quark–antiquark and diquark channels, then in the (μ, T)-phase diagram the superconducting phase is suppressed by spatially inhomogeneous chiral spiral phase with broken chiral symmetry. In contrast, in the above mentioned original Chodos et al. model, where only the opportunity for homogeneous condensates is taken into account, the superconducting phase is realized at sufficiently high values of μ at arbitrary values of G2>0, including the interval 0<G2<G1.

MAGNETIC MONOPOLES AND CHIRAL ASYMMETRY

The asymmetry, between electric (E) and magnetic (H) fields of Maxwell's equation is here analyzed by using the concept of chirality. The chiral spinorial approach sets the stage for the construction of a more general theory of spin-1 particles than usual electrodynamics. Chiral components of a rank-2 spinor field are taken as the dynamic variables of the theory. A rank-2 spinor accommodates another particle (the magnetic photon). This new particle emerges naturally from chiral invariance arguments. The nonexistence, in nature, of such a particle is the reason for the nonexistence of monopoles and the asymmetry in Maxwell's equation. The existence of magnetic monopoles would restore the symmetry of Maxwell's equation. We establish, in this way, at a very formal level, the connection between magnetic monopoles and chiral asymmetry.

CHIRAL ASYMMETRY AND GRAVITATION THOERY

In this letter we apply an alternative approach, recently developed, to the description of massless particles of arbitrary spin to the case of spin-two particles. This provides a non-geometrical approach to the theory of linearized gravitation. Within this method the chiral components of a spinor field are treated as independent field variables. The free field Lagrangian is built up from the requirement of chiral invariance. This formulation is parallel to the neutrino theory and leads to a formulation that generalizes, to particles of spin-two, the two-component neutrino theory. At the free field level the analog of curvature tensor, spin connection tensor, and metric tensor are independent quantities. By introducing left–right asymmetric linear interactions of these chiral components we get the linearized gravitation theory.

CHIRALLY EXTENDED QUANTUM CHROMODYNAMICS

We propose an extended Quantum Chromodynamics (XQCD) Lagrangian in which the fermions are coupled to elementary scalar fields through a Yukawa coupling which preserves chiral invariance. Our principle motivation is to find a new lattice formulation for QCD which avoids the source of critical slowing down usually encountered as the bare quark mass is tuned to the chiral limit. The phase diagram and the weak coupling limit for XQCD are studied. They suggest a conjecture that the continuum limit of XQCD is the same as the continuum limit of conventional lattice formulation of QCD. As examples of such universality, we present the large N solutions of two prototype models for XQCD, in which the mass of the spurious pion and sigma resonance go to infinity with the cut-off. Even if the universality conjecture turns out to be false, we believe that XQCD will still be useful as a low energy effective action for QCD phenomenology on the lattice. Numerical simulations are recommended to further investigate the possible benefits of XQCD in extracting QCD predictions.