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Rho-Rho interaction in unitary chiral perturbation theory revisited

10/24 2017
  • Title Rho-Rho interaction in unitary chiral perturbation theory revisited
  • Speaker
  • Date
  • Venue
    • Abstract

    CAS Key Laboratory of Theoretical Physics

    Institute of Theoretical Physics

     Chinese Academy of Sciences

    Seminar

    Title

    题目

    Rho-Rho interaction in unitary chiral perturbation theory revisited

    Speaker

    报告人

    耿立升　教授

    Affiliation

    所在单位

    		 北京航空航天大学

    Date

    日期

    2017年10月24日（周二）上午10:30

    Venue

    地点

    Room 6420, ITP NEW BUILDING

    Abstract

    摘要

    		 Studies based on unitary chiral perturbation theory show that the f0(1370) and f2(1270) may contain sizable rho-rho components. Such a picture has been tested in various scenarios, which all yield positive results. In a recent study, improvements to make the ρρ scattering relativistically covariant are made. The paper has a remarkable conclusion that the f2(1270) state disappears with a potential which is much more attractive than for J = 0, where a bound state is found, namely the f0(1370). We trace this abnormal conclusion to the fact that an “on shell” factorization of the potential is done in a region where this potential is singular and develops a large discontinuous and unphysical imaginary part. A method is developed, evaluating exactly the loops with full ρ propagators, and we show that they do not develop singularities and do not have an imaginary part below threshold. With the exact result for the loops we define an effective potential, which used with the Bethe Salpeter equation provides a state with J = 2 around the energy of the f2(1270). In addition, the coupling of the state to ρρ is evaluated and we find that this coupling and the T matrix around the energy of the bound state are remarkably similar to those obtained with a drastic approximation used previously in which the q2 terms of the propagators of the exchanged ρ mesons are dropped, once the cut off in the ρρ loop function is tuned to reproduce the bound state at the same energy.

    Contact person

    所内联系人

    		 郭奉坤