MULTI - QUARK HADRONS : PRODUCTION OF S = - 2 SYSTEMS. Page: 1 of 10
This article is part of the collection entitled: Office of Scientific & Technical Information Technical Reports and was provided to UNT Digital Library by the UNT Libraries Government Documents Department.
Extracted Text
The following text was automatically extracted from the image on this page using optical character recognition software:
BNL-69352
Multi-Quark hadrons: Production of S=-2 Systems
D. E. Kahana, S. H. Kahana
Physics Department, Brookhaven National Laboratory
Upton, NY 11973, USA
(August 26, 2002)
The general character of 4-quark (mesonic) and strange 6-quark (baryonic) quark systems is very
briefly reviewed a la Jaffe, i. e. in the MIT bag, and so far still possibly viable candidates are
indicated. The concentration is on the latter (S = -2) systems, with some attention given to
more likely to be discoverable light, doubly-strange nuclei. The two modes for generating doubly
strange, generally double-A nuclear systems, are considered and related to each other. Traditionally,
one employs the (K~, K+) reaction on a relatively light target and hopes to retain two units of
strangeness on a single final state fragment. Alternatively, heavy ion reactions can be used to
produce A-hyperons copiously and one seeks to observe coalescence of two of these particles into the
lightest S=-2 nucleus, the H-dibaryon. The complications arising from the presence of a repulsive
core in the baryon-baryon interaction on the production of the H are discussed. Also considered is
the possible presence in the data from the AGS experiment E906, of slightly heavier S= -2 nuclei,
in particular in the system AAH.
I. INTRODUCTION
One very interesting question which arises in our search for macroscopic examples of quark-gluon matter is the
apparent absence, or at least the paucity of examples of elementary hadrons possessing more than three quarks.
There is perhaps one good candidate for an exotic meson consisting of two quarks combined with two anti-quarks:
viz the Xi1410 thought to be an IG jPC = 1-(1-+) state [1], but there is not likely an equally good candidate for a
gg +ggg+ - ". state or glueball. The perhaps more distinguishable H-dibaryon [2] has also not yet shown up on its own
in any experimental search and it has proved to be equally elusive in theoretical analysis. Surely, however, strange
matter must be present at the heart of virtually all gravitationally collapsed objects [3]. Nothing new is offered here
with respect to the mesonic possibilities: but the presence of more than a single strange quark in dibaryons and light
nuclei is explored in more detail.
During this presentation, we wish to cover two apparently disparate subjects: (1) the production of the H-dibaryon
in both elementary and heavy ion induced reactions, and (2) the generation of very light to moderately light S = -2
hypernuclei. Both subjects concern S = -2 systems and they are quite possibly tied together by the possible presence
within finite systems of a hybrid H, possibly constructed both from dibaryon AA and from 6-quark bag like (uuddss)
components, viz:
I)= alAA) + #31q6)(1
with a, 3 being amplitudes for the two-body and 6-quark components of the hybrid state. The purely Jaffe-like H
state [2] corresponds to / = 1. Our coalescence calculation is independent of this parameter. The procedure we follow
to estimate the effect of the hard core on entry from a doorway AA state into the final H is applicable to either the
pure bag or hybrid cases.
We begin by indicating that the seeming absence of the H in existing searches is perhaps attributable to repulsive
(soft-core) forces in the baryon-baryon system, which prevent penetration to short range of a AA pair during any
mechanism for formation of the dihyperon structure. However, one might anticipate to the contrary, that within a
finite nucleus two As could be held together for sufficient time to permit a short range structure to develop.
Since the first of these subjects, H-suppression, has been described elsewhere [4], it will only be briefly dealt with
here. To our knowledge all theoretical estimates of production rates [5,6], irrespective of mechanism, have overlooked
the possibility of a repulsive core in the baryon-baryon interaction at short distances. As we show, under reasonable
assumptions the core can lead to an appreciable diminution of H yield. We introduce this device in the context of
heavy ion collisions where a previous calculation [6] suggested a high formation probability, ~ 0.07 per central Au
+ Au collision. The AGS experiment E896 [7] is presently analysing some 100 million central Au + Au events and
could, in the light of this previous estimate, have provided a definitive search for the H. In Reference [4] we presented
an estimate of the extent to which a repulsive core might interfere with this hope.
We put forward first the simplest possible theoretical description of the multi-quark systems; then we consider
the, successful or otherwise, experimental searches for such objects. This is followed by a description of the related
attempts to produce multi-strange nuclei.1
Upcoming Pages
Here’s what’s next.
Search Inside
This article can be searched. Note: Results may vary based on the legibility of text within the document.
Tools / Downloads
Get a copy of this page or view the extracted text.
Citing and Sharing
Basic information for referencing this web page. We also provide extended guidance on usage rights, references, copying or embedding.
Reference the current page of this Article.
KAHANA,D.E. & KAHANA,S.H. MULTI - QUARK HADRONS : PRODUCTION OF S = - 2 SYSTEMS., article, June 10, 2002; Upton, New York. (https://digital.library.unt.edu/ark:/67531/metadc737158/m1/1/: accessed April 17, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.