Gordon Godfrey Theoretical Seminar 2006
"Super-Radiance".
a Mechanism for Formation of Narrow Hadronic Resonances
Prof.
Naftali Auerbach
Tel Aviv University
Date
12 pm, Tuesday, 7 March, 2006
School of Physics,
Room 5
Abstract:
The observation of a narrow peak around the energy of 1540 MeV in the
K+N system has caused considerable excitement and research activity.
It was suggested that the observed peak represents a pentaquark resonance,
the theta particle. Since this initial discovery many different experiments
(about 10) have found the peak around this energy. However, in about
the same number of experiments (usually using higher energy probes)
the theta was not seen. Moreover, the experiments that do observe the
theta peak often differ in the energy position of the resonance. The
determination of the widths is difficult because of experimental limitations.
Indirect considerations suggest that the width is smaller than 1 MeV.
In the seminar we discuss a mechanism that could produce narrow resonances
due to interference effects. The mechanism suggested is of generic nature
and can accommodate various models for the states involved. The central
point is that since one deals with a many-quark system a large number
of many-body states can be formed which interact via various mechanisms
including interference through decay. As a result of this interaction
a number of narrow states is generated, superimposed on a very wide
resonance(s) which makes up the background. This is similar to the formation
of giant resonances in nuclear physics.
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