1,532 research outputs found

    Quark distributions in QCD sum rules: unexpected features and paradoxes

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    Some very unusual features of the hadron structure functions, obtained in the generalized QCD sum rules, like the surprisingly strong difference between longitudinally and transversally polarized ρ\rho mesons structure functions and the strong suppression of the gluon sea in longitudinally polarized ρ\rho mesons are discussed. Also the problem of exact zero contribution of gluon condensates to pion and longitudinally polarized ρ\rho meson quark distributions is discussed.Comment: 9 pages, 5 fig

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

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    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

    Calculation of the pentaquark width by QCD sum rule

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    The pentaquark width is calculated in QCD sum rules. Result for ΓΘ\Gamma_{\Theta} show, that ΓΘ\Gamma_{\Theta} can vary in the region less than 1MeVMeV. The main conclusion is, that if pentaquark is genuine states then sum rules really predict the narrow width of pentaquark θ+\theta^+, and the suppression of the width is both parametrical and numerical.Comment: 8 Ppages, 3 figures,the numerical error was corrected, two figures are modified. In the limit of errors the result did not change significantl

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

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    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
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