740 research outputs found
Assignments of and baryons in the heavy quark-light diquark picture
We apply a new mass formula which is derived analytically in the relativistic
flux tube model to the mass spectra of and (\emph{Q} =
\emph{c} or \emph{b} quark) baryons. To this end, the heavy quark-light diquark
picture is employed. We find that all masses of the available and
states can be understood well. The assignments to these states do not
appear to contradict the strong decay properties. and
are assigned to the first radial excitations with .
and might be the 2\emph{P} states. The
and are the good 1\emph{D} candidates with
. is likely to be a 1\emph{D} state with . and favor the 1\emph{P}
assignments with and , respectively. We propose a search
for the state which can help to distinguish the
diquark and three-body schemes.Comment: 9 tables, more discussions and references adde
Low-lying charmed and charmed-strange baryon states
In this work, we systematically study the mass spectra and strong decays of
and charmed and charmed-strange baryons in the framework of
nonrelativistic constituent quark models. With the light quark cluster-heavy
quark picture, the masses are simply calculated by a potential model. The
strong decays are studied by the Eichten-Hill-Quigg decay formula. Masses and
decay properties of the well-established and states can be reproduced
by our method. can be assigned as a
or state. We prefer to interpret the
signal as a state although at present we cannot
thoroughly exclude the possibility that this is the same state as
. or could be
explained as the state or state,
respectively. We propose to measure the branching ratio of
in future,
which may disentangle the puzzle of this state. Our results support
as the first radial excited state of
with . The assignment of is analogous to
, \emph{i.e.}, a or
state. In addition, we predict some typical ratios
among partial decay widths, which are valuable for experimental search for
these missing charmed and charmed-strange baryons.Comment: 16 pages, 3 figures, 13 tables. Accepted by Eur. Phys. J.
The first Chinese student space shuttle getaway special program
The first Chinese Getaway Special program is described. Program organization, the student proposal evaluation procedure, and the objectives of some of the finalist's experiments are covered. The two experiments selected for eventual flight on the space shuttle are described in detail. These include: (1) the control of debris in the cabin of the space shuttle; and (2) the solidification of two immiscible liquids in space
Plastic avalanches in metal-organic framework crystals
The compressive properties of metal-organic framework (MOF) crystals are not
only crucial for their densification but also key in determining their
performance in many applications. We herein investigated the mechanical
responses of a classic crystalline MOF, HKUST-1 by using in situ compression
tests. A serrated flow accompanied by the unique strain avalanches was found in
individual and contacting crystals before their final flattening or fracture
with splitting cracks. The plastic flow with serrations is ascribed to the
dynamic phase mixing due to the progressive and irreversible local phase
transition in HKUST-1 crystals, as revealed by molecular dynamics and finite
element simulations. Such pressure-induced phase coexistence in HKUST-1
crystals also induces a significant loading-history dependence of their Young's
modulus. The observation of plastic avalanches in HKUST-1 crystals here not
only expands our current understanding of the plasticity of MOF crystals but
also unveils a novel mechanism for the avalanches and plastic flow in crystal
plasticity
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