Chirality violating condensates in QCD and their connection with zero mode solutions of quark Dirac equations

It is demonstrated, that chirality violating condensates in massless QCD arise entirely from zero mode solutions of Dirac equations in arbitrary gluon fields. The model is suggested, where the zero mode solutions are the ones for quarks, moving in the instanton field. Basing on this model were calculated the quark condensate magnetic susceptibilities of dimensions $3(\chi)$ and 5 ($\kappa$ and $\xi$). The good considence of the values $\chi,\kappa$ and $\xi$, obtained in this approach with ones, found from the hadronic spectrum ia a serious argument in favour, that instantons are the only source of chirality violating condensates in QCD. The temperature dependence of the quark condensate is discussed. It is shown that the phase transition, corresponding to the $T$-dependence of the quark condensate $\alpha(T)$ as an order parameter, is of the type of crossover.Comment: The talk presented of Gribov-80 Workshop, May 28-30, 2010, Trieste, 8 pages, minor change

Spontaneous violation of chiral symmetry in QCD vacuum is the origin of baryon masses and determines baryon magnetic moments and their other static properties

A short review is presented of the spontaneous violation of chiral symmetry in QCD vacuum. It is demonstrated, that this phenomenon is the origin of baryon masses in QCD. The value of nucleon mass is calculated as well as the masses of hyperons and some baryonic resonances and expressed mainly through the values of quark condensates -- $, ~q=u,d,s$ -- the vacuum expectation values (v.e.v.) of quark field. The concept of vacuum expectation values induced by external fields is introduced. It is demonstrated that such v.e.v. induced by static electromagnetic field results in quark condensate magnetic susceptibility, which plays the main role in determination of baryon magnetic moments. The magnetic moments of proton, neutron and hyperons are calculated. The results of calculation of baryon octet $\beta$-decay constants are also presented.Comment: 13 pades, 5 figures. Dedicated to 85-birthday of acad. S.T.Belyaev. To be published in Phys.At.Nucl. Few references are correcte

Experimental demonstration of Aharonov-Casher interference in a Josephson junction circuit

A neutral quantum particle with magnetic moment encircling a static electric charge acquires a quantum mechanical phase (Aharonov-Casher effect). In superconducting electronics the neutral particle becomes a fluxon that moves around superconducting islands connected by Josephson junctions. The full understanding of this effect in systems of many junctions is crucial for the design of novel quantum circuits. Here we present measurements and quantitative analysis of fluxon interference patterns in a six Josephson junction chain. In this multi-junction circuit the fluxon can encircle any combination of charges on five superconducting islands, resulting in a complex pattern. We compare the experimental results with predictions of a simplified model that treats fluxons as independent excitations and with the results of the full diagonalization of the quantum problem. Our results demonstrate the accuracy of the fluxon interference description and the quantum coherence of these arrays

The "radiative Delta -> N gamma" decay in light cone QCD

The "g_{Delta N gamma}" coupling for the "Delta -> N gamma" decay is calculated in framework of the light cone QCD sum rules and is found to be g_{Delta N gamma} = (1.6 pm 0.2) GeV^(-1). Using this value of g_{Delta N gamma} we estimate the branching ratio of the Delta^+ -> N gamma decay, which is in a very good agreement with the experimental result.Comment: 9 pages, 1figures, LaTeX formatte

Impurity effects in a two--dimensional system with Dirac spectrum

It is demonstrated that in a two--band 2D system the resonance state is manifested close to the energy of the Dirac point in the electron spectrum for the sufficiently large impurity perturbation. With increasing the impurity concentration, the electron spectrum undergoes the rearrangement, which is characterized by the opening of the broad quasi--gap in the vicinity of the nodal point. If the critical concentration for the spectrum rearrangement is not reached, the domain of localized states remains exponentially small compared to the bandwidth.Comment: 4 pages, 1 figur

Magnetic Moments of Decuplet Baryons in Light Cone QCD

We calculate the magnetic moments of decuplet baryons containing strange quarks within the framework of light cone QCD sum rules taking into account the SU(3) flavor symmetry breaking effects. It is obtained that magnetic moments of the neutral \sso and \xis0 baryons are mainly determined by the SU(3) breaking terms. A comparison of our results on the magnetic moments of the decuplet baryons with the predictions of other approaches is presented.Comment: Latex, 20 pages, 6 figure

Numerical simulation evidence of spectrum rearrangement in impure graphene

By means of numerical simulation we confirm that in graphene with point defects a quasigap opens in the vicinity of the resonance state with increasing impurity concentration. We prove that states inside this quasigap cannot longer be described by a wavevector and are strongly localized. We visualize states corresponding to the density of states maxima within the quasigap and show that they are yielded by impurity pair clusters

Exclusive photoproduction of hard dijets and magnetic susceptibility of QCD vacuum

We argue that coherent production of hard dijets by linearly polarized real photons can provide direct evidence for chirality violation in hard processes, the first measurement of the magnetic susceptibility of the quark condensate and the photon distribution amplitude. It can also serve as a sensitive probe of the generalized gluon parton distribution. Numerical calculations are presented for HERA kinematics.Comment: 4 pages, 4 figure