392 research outputs found
Comment on ``Confirmation of the Sigma Meson''
We comment on the recent paper by N.A. Tornqvist and M. Roos published in
Phys. Rev. Lett. 76, 1575 (1996).Comment: 3 pages (LaTeX), 1 PostScript Figur
Estimating sigma-meson couplings from D \to 3\pi decays
Using recent experimental evidence from E791 on the sigma meson in D \to 3\pi
decays, we study the relevant couplings in D \to \sigma \pi and \sigma \to \pi\
pi within the accepted theoretical framework for non leptonic D decays. We also
review the linear sigma model, finding that it gives a description which is
consistent with the experimental data.Comment: 6 pages, no figures. Final version accepted for publication as a
Brief Report in Physical Review
Masses of tetraquarks with two heavy quarks in the relativistic quark model
Masses of tetraquarks with two heavy quarks and open charm and bottom are
calculated in the framework of the diquark-antidiquark picture in the
relativistic quark model. All model parameters were regarded as fixed by
previous considerations of various properties of mesons and baryons. The light
quarks and diquarks are treated completely relativistically. The c quark is
assumed to be heavy enough to make the diquark configurations dominating. The
diquarks are considered not to be point-like but to have an internal structure
which is taken into account by the calculated diquark form factor entering the
diquark-gluon interaction. It is found that all the (cc)(\bar q\bar q')
tetraquarks have masses above the thresholds for decays into open charm mesons.
Only the I(J^P)=0(1^+) state of (bb)(\bar u\bar d) lies below the BB* threshold
and is predicted to be narrow.Comment: 12 pages; version to be published in Phys.Rev.
A new look at scalar mesons
Light scalar mesons are found to fit rather well a diquark-antidiquark
description. The resulting nonet obeys mass formulae which respect, to a good
extent, the OZI rule. OZI allowed strong decays are reasonably reproduced by a
single amplitude describing the switch of a qbar-q pair, which transforms the
state into two colourless pseudoscalar mesons. Predicted heavy states with one
or more quarks replaced by charm or beauty are briefly described; they should
give rise to narrow states with exotic quantum numbers.Comment: 4 pages, 1 figure, misprints corrected, references added, accepted
for publication in Phys. Rev. Let
Total Widths And Slopes From Complex Regge Trajectories
Maximally complex Regge trajectories are introduced for which both Re
and Im grow as ( small and
positive). Our expression reduces to the standard real linear form as the
imaginary part (proportional to ) goes to zero. A scaling formula for
the total widths emerges: constant for large M, in very
good agreement with data for mesons and baryons. The unitarity corrections also
enhance the space-like slopes from their time-like values, thereby resolving an
old problem with the trajectory in charge exchange. Finally, the
unitarily enhanced intercept, , \nolinebreak is in
good accord with the Donnachie-Landshoff total cross section analysis.Comment: 9 pages, 3 Figure
Baryons with Two Heavy Quarks as Solitons
Using the chiral soliton model and heavy quark symmetry we study baryons
containing two heavy quarks. If there exists a stable (under strong
interactions) meson consisting of two heavy quarks and two light ones, then we
find that there always exists a state of this meson bound to a chiral soliton
and to a chiral anti-soliton, corresponding to a two heavy quark baryon and a
baryon containing two heavy anti-quarks and five light quarks, or a
``heptaquark".Comment: 7 pages and 2 postscript figures appended, LaTex, UCI-TR 94-3
Mechanism for a next-to-lowest lying scalar meson nonet
Recent work suggests the existence of a non-conventional lowest-lying scalar
nonet containing the a0(980). Then the a0(1450) and also the K0*(1430) are
likely candidates to belong to a conventional p-wave nonet. However
a comparison of their properties with those expected on this basis reveals a
number of puzzling features. It is pointed out that these puzzles can be
resolved in a natural and robust way by assuming a ``bare'' conventional p-wave
scalar nonet to mix with a lighter four quark
scalar nonet to form new ``physical'' states. The essential mechanism is driven
by the fact that the isospinor is lighter than the isovector in the unmixed multiplet.Comment: 22 pages, 6 figure
On Deusons or Deuteronlike Meson-Meson Bound States
The systematics of deuteronlike two-meson bound states, {\it deusons}, is
discussed. Previous arguments that many of the present non- states are
such states are elaborated including, in particular, the tensor potential. For
pseudoscalar states the important observation is made that the centrifugal
barrier from the P-wave can be overcome by the and terms of the
tensor potential. In the heavy meson sector one-pion exchange alone is strong
enough to form at least deuteron-like and composites
bound by approximately 50 MeV, while and states are
expected near the threshold.Comment: Invited talk at the Hadron93 International Conf. on Hadron
Spectroscopy, Como, Italy 22.-25.6. 1993. 5 pages in LATEX HU-SEFT R 1993-13
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