Related papers: Classification of Coupled-Channel Near-Threshold S…
Tremendous progress has been made experimentally in the hadron spectrum containing heavy quarks in the last two decades. It is surprising that many resonant structures are around thresholds of a pair of heavy hadrons. There should be a…
We reduce the problem of many-channel hadron scattering at nonrelativistic energies to calculations on the scale of a few fermis. Having thus disentangled kinematics from interior quark dynamics, we study their interplay when a quark state…
We study the behavior of the cusp structures focusing on the isospin symmetry breaking effects. The properties of the exotic hadrons are reflected in the shape of the cusp structures. In realistic hadron scatterings, the threshold energies…
We study the behavior of the cusp structures focusing on the isospin-breaking effects. The properties of the near-threshold exotic hadrons are encoded in the shapes of the cusp structures. In hadron scattering, it is often the case that the…
We investigate the effect of decay channels on the near-threshold mass scaling by employing potential models. By varying the attractive strength of a square-well potential, we examine the pole trajectory associated with the transition of an…
Numerous quarkonium(like) states lying near $S$-wave thresholds are observed experimentally. We propose a self-consistent approach to these near-threshold states compatible with unitarity and analyticity. The underlying coupled-channel…
When an exotic hadron locates near the threshold with the channel couplings, the internal structure of the exotic hadron is related to the scattering length. To incorporate the threshold effect, the Flatt\'{e} amplitude has been often used…
We discuss in general terms pole trajectories of resonances coupling to a continuum channel as some strength parameter is varied. It is demonstrated that, regardless the underlying dynamics, the trajectories of poles that couple to the…
Excited hadrons are seen as resonances in the scattering of lighter stable hadrons like $\pi$, $K$ and $\eta$. Many decay into multiple final states necessitating coupled-channel analyses. Recently it has become possible to obtain…
The near-threshold exotic hadrons such as $T_{cc}$ and $X(3872)$ are naively considered as the hadronic molecular state from the viewpoint of the low-energy universality. However, it is also known that the elementary dominant state is not…
We study the structure of two-body s-wave bound states as well as resonances in the threshold energy region. We focus on the single-channel scattering where the scattering length and the effective range are given by real numbers. It is…
We discuss the general behavior of the near-threshold scattering amplitude with channel couplings. The signal of the exotic hadrons near the threshold may manifest as a dip structure in the cross section originated from a zero point of the…
The possible existence of nucleon-antinucleon bound states has been studied for decades. We investigate the $e^+e^-\to p\bar{p}$ and $e^+e^-\to n\bar{n}$ cross sections in the nonrelativistic effective field theory framework. The…
In the past two decades, one of the most puzzling phenomena discovered in hadron physics is that a nominal hadronic state can actually correspond to two poles on the complex energy plane. This phenomenon was first noticed for the…
Matching theoretical predictions to experimental data remains a central challenge in hadron spectroscopy. In particular, the identification of new hadronic states is difficult, as exotic signals near threshold can arise from a variety of…
It is well known that the quasinormal modes (or resonant states) of photonic structures can be associated with the poles of the scattering matrix of the system in the complex-frequency plane. In this work, the inverse problem, i.e., the…
We discuss the composite nature of hadrons appearing near the s-wave two-hadron threshold. Generalizing the Weinberg's weak-binding relation for stable bound states, we show that the compositeness of near-threshold resonances and…
We critically examine the $\bar{K}N$ coupled-channel approach presented in [1] and demonstrate that it violates constraints imposed by chiral symmetry of QCD. The origin of this violation can be traced back to the off-shell treatment of the…
In the past few years a wealth of high quality data has made possible to test current theoretical ideas about the properties of hadrons subject to extreme conditions of density and temperature. The relativistic heavy-ion program carried out…
Near-threshold collectivization of continuum shell model eigenstates is investigated in $^{20}$O on the example of B(E$\lambda$) decays of 4$^+$ states in the vicinity of elastic and inelastic neutron threshold. Changes of the…