361 research outputs found

    Universality in a Class of Q-Ball Solutions: An Analytic Approach

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    The properties of Q-balls in the general case of a sixth order potential have been studied using analytic methods. In particular, for a given potential, the initial field value that leads to the soliton solution has been derived and the corresponding energy and charge have been explicitly evaluated. The proposed scheme is found to work reasonably well for all allowed values of the model parameters.Comment: 9 Pages, 6 Figure

    On decay of large amplitude bubble of disoriented chiral condensate

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    The time evolution of initially formed large amplitude bubble of disoriented chiral condensate (DCC) is studied. It is found that the evolution of this object may have a relatively long pre-decay stage. Simple explanation of such delay of the DCC bubble decay is given. This delay is related to the existence of the approximate solutions of multi-soliton type of the corresponding radial sine-Gordon equation in (3+1) dimensions at large bubble radius.Comment: 6 pages, LaTeX, 5 PostScript figure

    The bubbles of matter from multiskyrmions

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    The multiskyrmions with large baryon number B given by rational map (RM) ansaetze can be described reasonably well within the domain wall approximation, or as spherical bubbles with energy and baryon number density concentrated at their boundary. A special class of profile functions is considered approximating the true profile and domain wall behaviour at the same time. An upper bound is obtained for the masses of RM multiskyrmions which is close to the calculated masses, especially at large B. The gap between rigorous upper and lower bounds for large B multiskyrmions is less than 4%. The basic properties of such bubbles of matter are investigated, some of them being of universal character, i.e. they do not depend on baryon number of configuration and on the number of flavors. As a result, the lagrangian of the Skyrme type models provides field theoretical realization of the bag model of special kind.Comment: 7 pages, no figure

    Kink-antikink interactions in the double sine-Gordon equation and the problem of resonance frequencies

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    We studied the kink-antikink collision process for the "double sine-Gordon" (DSG) equation in 1+1 dimensions at different values of the potential parameter R>0R>0. For small values of RR we discuss the problem of resonance frequencies. We give qualitative explanation of the frequency shift in comparison with the frequency of the discrete level in the potential well of isolated kink. We show that in this region of the parameter RR the effective long-range interaction between kink and antikink takes place.Comment: 9 pages, LaTeX, 4 figures (eps

    Multiskyrmions and baryonic bags

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    Analytical treatment of skyrmions given by rational map (RM) ansaetze proposed recently for the Skyrme model is extended to the model including the 6-th order term in chiral fields derivatives in the lagrangian (the SK6 variant of the model) and used for calculation of different properties of multiskyrmions. For special class of profile functions approximating the true profile and the domain wall behaviour at the same time, the masses and other static properties of multiskyrmions are expressed in terms of the Euler-type integrals. An upper bound is obtained for the masses of RM multiskyrmions which is close to the calculated masses, especially at large B. The gap between rigorous upper bound and lower bound, obtained for the SK6 model as well, for large B multiskyrmions is less than 9%, in comparison with about 4% for the SK4 (Skyrme) variant. The basic properties of such bubbles of matter are investigated, some of them, e.g. the thickness of the bubbles envelope, being of universal character, i.e. they do not depend on baryon number of configuration, or reveal a simple and natural dependence. The dependence of these properties on the number of flavours is absent or very weak in both models. Qualitatively, the properties of the baryonic bags are the same for the SK6 and SK4 variants of the model, although differ in some details.Comment: 16 pages, no figure

    Ferromagnetism in the Mott insulator Ba2NaOsO6

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    Results are presented of single crystal structural, thermodynamic, and reflectivity measurements of the double-perovskite Ba2NaOsO6. These characterize the material as a 5d^1 ferromagnetic Mott insulator with an ordered moment of ~0.2 Bohr magnetons per formula unit and TC = 6.8(3) K. The magnetic entropy associated with this phase transition is close to Rln2, indicating that the quartet groundstate anticipated from consideration of the crystal structure is split, consistent with a scenario in which the ferromagnetism is associated with orbital ordering.Comment: 5 pages, 5 figures, added reference

    Low molecular weight thymic factor inhibits histamine release from basophils

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    Low molecular weight thymic factor stimulates the suppressor function of T-lymphocytes, increases cAMP content (but not cGMP) in lymphocytes and inhibits histamine release from sensitized basophils. The mechanisms of LTF action are discussed

    Towards an Abelian Formulation of Lattice QCD Confinement

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    We probe for operators occurring in the APQCD(``abelian-projected QCD'') action by evaluating abelian-projected 11-plaquette spectral densities in pure gauge SU(3)SU(3) fixed to maximal abelian gauge. Couplings BAPQCD(q,L)B_{APQCD}(q,L) are extracted from the spectral densities for each representation qq, L×LL\times L plaquette. While APQCD is dominated by a q=L=1q=L=1 resonance, we also find evidence for weakly coupled L=2L=2 plaquettes. Moreover, since BAPQCD(1,1)>BQED(1,1)B_{APQCD}(1,1) > B_{QED}(1,1) even if βQED>βc\beta_{QED} > \beta_c, L>1L>1 plaquettes must be significant since APQCD is confining.Comment: 1+11 pages, fixed minor postscript erro
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