1,057 research outputs found

    Comment on "Remark on the external-field method in QCD sum rules"

    Get PDF
    It is proved, that suggested by Jin modified formalism in the external-field method in QCD sum rules exactly coincides with the formalism used before. Therefore, unlike the claims of ref.1, this formalism cannot improve the predictability and reliability of external-field sum rule calculations in comparison with those, done by the standard approach. PACS number(s): 12.38.Lg, 11.55.HxComment: 5 pages, RevTe

    Pentaquark decay is suppressed by chirality conservation

    Full text link
    It is shown, that if the pentaquark Θ+=uuddsˉ\Theta^+ = uudd\bar{s} baryon can be represented by the local quark current ηΘ\eta_{\Theta}, its decay Θ+→nK+(pK0)\Theta^+ \to n K^+ (p K^0) is forbidden in the limit of chirality conservation. The Θ+\Theta^+decay width Γ\Gamma is proportional to αs2<0∣qˉq∣0>2\alpha^2_s < 0 | \bar{q} q | 0 >^2, where , q=u,d,sq = u,d,s is quark condensate, and, therefore, is strongly suppressed. Also the polarization operator of the pentaquark current with isospin 1 is calculated using the operator product expansion and estimation for it mass is obtained .Comment: 4 pages, 1 fig, typos correcte

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

    Full text link
    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, ~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 β\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
    • …
    corecore