Workshop on the Physics of Excited Nucleons, Sept. 5-8, 2007, Bonn, Germany – Alexander Titov 1

Alexander TitovForschungzentrum Rossendorf/Dresden

andJoint Institute for Nuclear Research Dubna

Photoproduction of meson off the deuteron

near threshold

Workshop on the Physics of Excited Nucleons

PRC 76, 035202 (2007)

Workshop on the Physics of Excited Nucleons, Sept. 5-8, 2007, Bonn, Germany – Alexander Titov 2

Talk OutlineTalk Outline

Motivation: puzzles in p->p photoproduction (LEPS)

Coherent D->Dreaction In-coherent D->npreaction Spin-density matrix elements Summary

Workshop on the Physics of Excited Nucleons, Sept. 5-8, 2007, Bonn, Germany – Alexander Titov 3

A.T.&T.-S.H.Lee, PRC 67 (2003)

previous experience in reaction

Motivation:

In following we discuss the diffractive part

Workshop on the Physics of Excited Nucleons, Sept. 5-8, 2007, Bonn, Germany – Alexander Titov 4

Puzzle # 1

Workshop on the Physics of Excited Nucleons, Sept. 5-8, 2007, Bonn, Germany – Alexander Titov 5

Puzzle # 2

Workshop on the Physics of Excited Nucleons, Sept. 5-8, 2007, Bonn, Germany – Alexander Titov 6

Nature of the bump: The large amount of un-natural parity ( meson)exchange can not produce the bump:

But this admixture of un-natural parity exchange gives sizable background for possible (real) interference

Workshop on the Physics of Excited Nucleons, Sept. 5-8, 2007, Bonn, Germany – Alexander Titov 7

Pomeron: modified Donnachie-Landshoff model

PS – exchange

Workshop on the Physics of Excited Nucleons, Sept. 5-8, 2007, Bonn, Germany – Alexander Titov 8

Workshop on the Physics of Excited Nucleons, Sept. 5-8, 2007, Bonn, Germany – Alexander Titov 9

coherent

incoherent

Workshop on the Physics of Excited Nucleons, Sept. 5-8, 2007, Bonn, Germany – Alexander Titov 10

coherent

incoherent

Workshop on the Physics of Excited Nucleons, Sept. 5-8, 2007, Bonn, Germany – Alexander Titov 11

Photoproduction from iso-scalar nucleon

Workshop on the Physics of Excited Nucleons, Sept. 5-8, 2007, Bonn, Germany – Alexander Titov 12

Workshop on the Physics of Excited Nucleons, Sept. 5-8, 2007, Bonn, Germany – Alexander Titov 13

Workshop on the Physics of Excited Nucleons, Sept. 5-8, 2007, Bonn, Germany – Alexander Titov 14

Workshop on the Physics of Excited Nucleons, Sept. 5-8, 2007, Bonn, Germany – Alexander Titov 15

GJ system

Workshop on the Physics of Excited Nucleons, Sept. 5-8, 2007, Bonn, Germany – Alexander Titov 16

H system

Workshop on the Physics of Excited Nucleons, Sept. 5-8, 2007, Bonn, Germany – Alexander Titov 17

Workshop on the Physics of Excited Nucleons, Sept. 5-8, 2007, Bonn, Germany – Alexander Titov 18

Workshop on the Physics of Excited Nucleons, Sept. 5-8, 2007, Bonn, Germany – Alexander Titov 19

SummarySummary

2. There is no bump-like behavior in reaction. The model satisfactory unpolarized cross sections and spin observables, which, in particular, indicate to elimination of the un-natural parity exchange processes.

3. Possible explanation of the existence of the bump-like structure in and its absence in reaction may indicate for contribution exotic channel with properties of the scalar – isovector meson exchange.

1. The model describes reasonably and spin

observables in reaction in diffraction region

at finite |t |, but it fails in description of the bump-like

behavior of at