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  Location: Home >  Research Activities >  Seminar
Rho-Rho interaction in unitary chiral perturbation theory revisited
2017-10-24     Text Size:  A

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
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