5 research outputs found
Model-Independent Predictions for Low Energy Isoscalar Heavy Baryon Observables in the Combined Heavy Quark and Large Expansion
Model-independent predictions for excitation energies, semileptonic form
factors and electromagnetic decay rates of isoscalar heavy baryons and their
low energy excited states are discussed in terms of the combined heavy quark
and large expansion. At leading order, the observables are completely
determined in terms of the known excitation energy of the first excited state
of . At next-to-leading order in the combined expansion all heavy
baryon observables can be expressed in a model-independent way in terms of two
experimentally measurable quantities. We list predictions at leading and
next-to-leading order.Comment: 7 pages, LaTe
Excited Heavy Baryons and Their Symmetries III: Phenomenology
Phenomenological applications of an effective theory of low-lying excited
states of charm and bottom isoscalar baryons are discussed at leading and
next-to-leading order in the combined heavy quark and large expansion.
The combined expansion is formulated in terms of the counting parameter
; the combined expansion is in powers of
. We work up to next-to-leading order. We obtain
model-independent predictions for the excitation energies, the semileptonic
form factors and electromagnetic decay rates. The spin-averaged mass of the
doublet of the first orbitally excited sate of is predicted to be
approximately . It is shown that in the combined limit at leading and
next-to-leading order there is only one independent form factor describing
; similarly, and
decays are described by a single independent form factor. These form factors
are calculated at leading and next-to-leading order in the combined expansion.
The electromagnetic decay rates of the first excited states of and
are determined at leading and next-to leading order. The ratio of
radiative decay rates is predicted to be approximately
0.2, greatly different from the heavy quark effective theory value of unity.Comment: 21 pages, 2 figure
Threshold effects in excited charmed baryon decays
Motivated by recent results on charmed baryons from CLEO and FOCUS, we
reexamine the couplings of the orbitally excited charmed baryons. Due to its
proximity to the [Sigma_c pi] threshold, the strong decays of the
Lambda_c(2593) are sensitive to finite width effects. This distorts the shape
of the invariant mass spectrum in Lambda_{c1}-> Lambda_c pi^+pi^- from a simple
Breit-Wigner resonance, which has implications for the experimental extraction
of the Lambda_c(2593) mass and couplings. We perform a fit to unpublished CLEO
data which gives M(Lambda_c(2593)) - M(Lambda_c) = 305.6 +- 0.3 MeV and h2^2 =
0.24^{+0.23}_{-0.11}, with h2 the Lambda_{c1}-> Sigma_c pi strong coupling in
the chiral Lagrangian. We also comment on the new orbitally excited states
recently observed by CLEO.Comment: 9 pages, 3 figure