arXiv:0812.1617·v2·Nuclear Theory

Combined study of gamma p to eta p and pi-p to eta n in a chiral constituent quark approach

Within a chiral constituent quark model approach, $η$ -meson production on the proton {\it via} electromagnetic and hadron probes are studied. With few parameters, differential cross-section and polarized beam asymmetry for \gamma p \to \eta p $an dd i f f er e n t ia l cr osssec t i o n f or$ \pi^- p\to \eta n $p r ocesses a r ec a l c u l a t e d an d s u ccess f u l l y co m p a r e d w i t h t h e d a t ain t h ece n t er - o f - ma sse n er g y r an g e f r o m t h r es h o l d u pt o 2 G e V . T h e f i v e k n o w n r eso nan ces$ S_{11}(1535) $,$ S_{11}(1650) $,$ P_{13}(1720) $,$ D_{13}(1520) $, an d$ F_{15}(1680) $a r e f o u n d t o b e d o minan t in t h er e a c t i o nm ec hani s m s inb o t h c hann e l s . P oss ib l er o l es pl ai e d b y n e w r eso nan ces a r e a l so in v es t i g a t e d an d in t h e p h o t o p r o d u c t i o n c hann e l, s i g ni f i c an t co n t r ib u t i o n f r o m$ S_{11} $- an d$ D_{15} $- r eso nan ces, w i t hma sses a r o u n d 1715 M e V an d 2090 M e V, r es p ec t i v e l y, a r e d e d u ce d . F or t h eso - c a l l e d mi ss in g r eso nan ces, n oe v i d e n ce i s f o u n d w i t hin t h e in v es t i g a t e d r e a c t i o n s . T h e h e l i c i t y am pl i t u d es an dd ec a y w i d t h so f$ N^* \to \pi N, \eta N$ are also presented, and found consistent with the PDG values.

Comments: 23 pages,5 figures

Combined study of gamma p to eta p and pi-p to eta n in a chiral constituent quark approach

Abstract

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