30,683 research outputs found
The recoil correction and spin-orbit force for the possible and states
In the framework of the one-boson exchange model, we have calculated the
effective potentials between two heavy mesons and from the t- and u-channel -, -, -, - and
-meson exchanges. We keep the recoil corrections to the and systems up to , which
turns out to be important for the very loosely bound molecular states. Our
numerical results show that the momentum-related corrections are favorable to
the formation of the molecular states in the , in the
and systems.Comment: 12 pages, 9 figures. arXiv admin note: substantial text overlap with
arXiv:1403.404
Hidden-Charm Tetraquarks and Charged Zc States
Experimentally several charged axial-vector hidden-charm states were
reported. Within the framework of the color-magnetic interaction, we have
systematically considered the mass spectrum of the hidden-charm and
hidden-bottom tetraquark states. It is impossible to accommodate all the three
charged states , and within the axial vector
tetraquark spectrum simultaneously. Not all these three states are tetraquark
candidates. Moreover, the eigenvector of the chromomagnetic interaction
contains valuable information of the decay pattern of the tetraquark states.
The dominant decay mode of the lowest axial vector tetraquark state is while its and modes are strongly suppressed,
which is in contrast with the fact that the dominant decay mode of
and is and respectively. We emphasize
that all the available experimental information indicates that is a
very promising candidate of the lowest axial vector hidden-charm tetraquark
state
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
Recommended from our members
Assessing the detailed time course of perceptual sensitivity change in perceptual learning.
The learning curve in perceptual learning is typically sampled in blocks of trials, which could result in imprecise and possibly biased estimates, especially when learning is rapid. Recently, Zhao, Lesmes, and Lu (2017, 2019) developed a Bayesian adaptive quick Change Detection (qCD) method to accurately, precisely, and efficiently assess the time course of perceptual sensitivity change. In this study, we implemented and tested the qCD method in assessing the learning curve in a four-alternative forced-choice global motion direction identification task in both simulations and a psychophysical experiment. The stimulus intensity in each trial was determined by the qCD, staircase or random stimulus selection (RSS) methods. Simulations showed that the accuracy (bias) and precision (standard deviation or confidence bounds) of the estimated learning curves from the qCD were much better than those obtained by the staircase and RSS method; this is true for both trial-by-trial and post hoc segment-by-segment qCD analyses. In the psychophysical experiment, the average half widths of the 68.2% credible interval of the estimated thresholds from the trial-by-trial and post hoc segment-by-segment qCD analyses were both quite small. Additionally, the overall estimates from the qCD and staircase methods matched extremely well in this task where the behavioral rate of learning is relatively slow. Our results suggest that the qCD method can precisely and accurately assess the trial-by-trial time course of perceptual learning
The Spin-orbit force, recoil corrections and possible and molecular states
In the framework of the one boson exchange model, we have calculated the
effective potentials between two heavy mesons and from the t- and u-channel , , , and
meson exchange with four kinds of quantum number: ,
; , ; , ; ,
. We keep the recoil corrections to the and system up to . The spin orbit force appears at
, which turns out to be important for the very loosely bound
molecular states. Our numerical results show that the momentum-related
corrections are unfavorable to the formation of the molecular states in the
, and , channels in the systems.Comment: 14 pages, 10 figure
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