20,527,561 research outputs found
Can Y(4140) be a tetraquark ?
In this exploratory study the spectrum of tetraquarks of type is calculated within a simple quark model with chromomagnetic
interaction and effective quark masses extracted from meson and baryon spectra.
It is tempting to see if this spectrum can accommodate the resonance Y(4140),
observed by the CDF collaboration, but not yet confirmed. The results seem to
favour the J = 1 sector where the coupling to the VV channel is
nearly as small as that of X(3872), when described as a
tetraquark. This suggests that Y(4140) could possibly be the strange partner of
X(3872), in a tetraquark interpretation. However the sector J = 0
cannot entirely be excluded. This work questions the practice of extracting
effective quark masses containing spin independent contributions, from mesons
and baryons, to be used in multiquark systems as well.Comment: new additional parts, published versio
Vibrational Satellites of CS, CS, and CS: Microwave Spectral Taxonomy as a Stepping Stone to the Millimeter-Wave Band
We present a microwave spectral taxonomy study of several hydrocarbon/CS
discharge mixtures in which more than 60 distinct chemical species, their more
abundant isotopic species, and/or their vibrationally excited states were
detected using chirped-pulse and cavity Fourier-transform microwave
spectroscopies. Taken together, in excess of 85 unique variants were detected,
including several new isotopic species and more than 25 new vibrationally
excited states of CS, CS, and CS, which have been assigned on the
basis of published vibration-rotation interaction constants for CS, or
newly calculated ones for CS and CS. On the basis of these precise,
low-frequency measurements, several vibrationally exited states of CS and
CS were subsequently identified in archival millimeter-wave data in the
253--280 GHz frequency range, ultimately providing highly accurate catalogs for
astronomical searches. As part of this work, formation pathways of the two
smaller carbon-sulfur chains were investigated using C isotopic
spectroscopy, as was their vibrational excitation. The present study
illustrates the utility of microwave spectral taxonomy as a tool for complex
mixture analysis, and as a powerful and convenient `stepping stone' to higher
frequency measurements in the millimeter and submillimeter bands.Comment: Accepted in PCC
Is S=1 for c=1?
The string in the Liouville field theory approach is shown to possess a
nontrivial tree-level -matrix which satisfies factorization property implied
by unitary, if all the extra massive physical states are included.Comment: 11 page
H^s versus C^0-weighted minimizers
We study a class of semi-linear problems involving the fractional Laplacian
under subcritical or critical growth assumptions. We prove that, for the
corresponding functional, local minimizers with respect to a C^0-topology
weighted with a suitable power of the distance from the boundary are actually
local minimizers in the natural H^s-topology.Comment: 15 page
Spectroscopy of the hidden-charm and tetraquarks
We calculate the spectrum of and
tetraquarks, where , and stand for light (), strange and charm
quarks, respectively, in a relativized diquark model, characterized by
one-gluon-exchange (OGE) plus confining potential. In the diquark model, a
() tetraquark configuration is made up of
a heavy-light diquark, (), and anti-diquark, (). According to our results, 13 charmonium-like observed states can be
accommodated in the tetraquark picture, both in the hidden-charm () and hidden-charm hidden-strange () sectors.Comment: Discussions extended, references adde
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