3,352 research outputs found
Isospin breaking, coupled-channel effects, and X(3872)
We re-investigate the possibility of X(3872) as a molecule with
within the framework of both the one-pion-exchange (OPE) model
and the one-boson-exchange (OBE) model. After careful treatment of the S-D wave
mixing, the mass difference between the neutral and charged mesons and
the coupling of the pair to , a loosely bound molecular
state X(3872) emerges quite naturally with large isospin violation in its
flavor wave function. For example, the isovector component is 26.24% if the
binding energy is 0.30 MeV, where the isospin breaking effect is amplified by
the tiny binding energy. After taking into account the phase space difference
and assuming the and come from a virtual omega and rho meson
respectively, we obtain the ratio of these two hidden-charm decay modes:
for the binding
energy being 0.3 MeV, which is consistent with the experimental value.Comment: published in Phys. Rev.
Deuteron-like states composed of two doubly charmed baryons
We present a systematic investigation of the possible molecular states
composed of a pair of doubly charmed baryons () or one doubly
charmed baryon and one doubly charmed antibaryon
within the framework of the one-boson-exchange-potential model. For the
spin-triplet systems, we take into account the mixing between the and
channels. For the baryon-baryon system with and , where and represent the group
representation and the isospin of the system, respectively, there exist loosely
bound molecular states. For the baryon-antibaryon system
with , and , there
also exist deuteron-like molecules. The molecular states
may be produced at LHC. The proximity of their masses to the threshold of two
doubly charmed baryons provides a clean clue to identify them.Comment: 18 pages, 8 figure
Possible hadronic molecules composed of the doubly charmed baryon and nucleon
We perform a systematical investigation of the possible deuteron-like bound
states with configuration , where denotes the
nucleon (anti-nucleon), in the framework of the one-boson-exchange-potential
model. In the spin-triplet sector we take into account both the and
channels due to non-vanishing tensor force. There exist several
candidates of the loosely bound molecular states for the and
systems, which lie below the threshold of
or . We also investigate the
possible loosely bound states with configurations and
. These molecular candidates may be searched for at Belle
II and LHC in the near future.Comment: 14 pages, 5 figure
Chiral Perturbation Theory and the Strong Interaction
We have calculated the potentials of the heavy (charmed or bottomed)
pseudoscalar mesons up to with the heavy meson chiral
perturbation theory. We take into account the contributions from the football,
triangle, box, and crossed diagrams with the 2 exchange and one-loop
corrections to the contact terms. We notice that the total 2-exchange
potential alone is attractive in the small momentum region in the channel
, , or , while repulsive in the channel .
Hopefully the analytical chiral structures of the potentials may be useful in
the extrapolation of the heavy meson interaction from lattice QCD simulation.Comment: 14 pages, 8 figures, 4 tables; discussion extended, references added,
version published in Phys. Rev.
The meson-exchange model for the interaction
In the present work, we apply the one-boson-exchange potential (OBEP) model
to investigate the possibility of Y(2175) and as bound states of
and respectively.
We consider the effective potential from the pseudoscalar -exchange and
-exchange, the scalar -exchange, and the vector
-exchange and -exchange. The and meson exchange
potential is repulsive force for the state and attractive for .
The results depend very sensitively on the cutoff parameter of the
-exchange () and least sensitively on that of the
-exchange (). Our result suggests the possible
interpretation of Y(2175) and as the bound states of
and respectively
Coupled-channel analysis of the possible , and molecular states
We perform a coupled-channel study of the possible deuteron-like molecules
with two heavy flavor quarks, including the systems of with
double charm, with double bottom and
with both charm and bottom, within the
one-boson-exchange model. In our study, we take into account the S-D mixing
which plays an important role in the formation of the loosely bound deuteron,
and particularly, the coupled-channel effect in the flavor space. According to
our calculation, the states and
with double charm, the states
,
and
with double bottom, and
the states and
with both charm and bottom are good
molecule candidates. However, the existence of the states
with double charm and
with both charm and bottom is ruled out.Comment: 1 figure added, published in Physical Review
Possible Deuteron-like Molecular States Composed of Heavy Baryons
We perform a systematic study of the possible loosely bound states composed
of two charmed baryons or a charmed baryon and an anti-charmed baryon within
the framework of the one boson exchange (OBE) model. We consider not only the
exchange but also the , , , and
exchanges. The mixing effects for the spin-triplets are also taken into
account. With the derived effective potentials, we calculate the binding
energies and root-mean-square (RMS) radii for the systems
, ,
,
and
. Our numerical results indicate that: (1)
the H-dibaryon-like state does not exist; (2) there may
exist four loosely bound deuteron-like states and
with small binding energies and large RMS radii.Comment: 17 pages, 32 figure
Negative-Index Refraction in a Lamellar Composite with Alternating Single Negative Layers
Negative-index refraction is achieved in a lamellar composite with
epsilon-negative (ENG) and mu-negative (MNG) materials stacked alternatively.
Based on the effective medium approximation, simultaneously negative effective
permittivity and permeability of such a lamellar composite are obtained
theoretically and further proven by full-wave simulations. Consequently, the
famous left-handed metamaterial comprising split ring resonators and wires is
interpreted as an analogy of such an ENG-MNG lamellar composite. In addition,
beyond the effective medium approximation, the propagating field squeezed near
the ENG/MNG interface is demonstrated to be left-handed surface waves with
backward phase velocity.Comment: 18 pages, 6 figure
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