A key issue in understanding hadron structure and quark confinement is the unquenching dynamics, i.e., quark-antiquark pair creation and annihilation in the hadrons. The exotic multi-quark states play an important role for the study of the unquenching dynamics. While the discoveries of exotic hadrons with heavy flavors convinced people the existence of multiquark states, the light quarks play...
This talk provides an overview of experimental searches for exotic baryon states, such as light pentaquark and hexaquark states, including $\Theta^+$, $P_{s\bar{s}}$, $P_{c\bar{c}}$, and $ H$-dibaryons, utilizing hadron beams. Special attention will be given to upcoming experiments at the hadron hall of J-PARC and the KLF at JLab. The talk will also highlight a proposed experiment to study...
In Belle II, various exotic and heavy hadrons can be produced in $e^+e^-$ collisions at and near the $\Upsilon(4S)$ resonance. I will report recent results from the Belle II experiment.
Two pion emission decays of radially excited quarkonia are investigated, including Upsilon(3S->1S, 2S; 2S->1S) and Psi(2S->1S). The coupling structure is of scalar-isoscalar type, and the strengths turn out to be in a similar order, implying a common mechanism in the couplings. Using transition matrix elements between these states, we obtain the J/psi-J/psi-2pi couplings, from which we...
We develop a reduced-profile maximum-entropy framework for reconstructing zero-skewness valence-quark generalized parton distributions from the proton and neutron electromagnetic form factors. Since elastic form factors constrain only x-integrated moments, the entropy functional is used as a regularizer within a low-dimensional profile ansatz. A numerical proof-of-concept shows that the...
Recent observations of pentaquark candidates in the hidden-charm sector have renewed interest in exotic baryons beyond the conventional three-quark picture. We propose a new search for a narrow pentaquark state with strangeness S = +1 using missing-mass spectroscopy of the d(K⁺, p)X reaction at J-PARC. The K1.8 beamline spectrometer and the high-resolution S-2S spectrometer will precisely...
We study doubly heavy baryons and pentaquarks in the pion mean-field picture. In this description, the two heavy quarks form a compact core, while the light quarks are described by a pion field. The approach provides a good description of the observed doubly charmed baryons and allows us to estimate the masses of unobserved charmed and bottom baryons. Applying the same framework to doubly...
The hidden-charm pentaquark structures (P_c(4312)), (P_c(4440)), and
(P_c(4457)) lie close to the (\Sigma_c \bar{D}^{()}) thresholds and are
frequently interpreted as hadronic molecular candidates. We investigate their
open-charm decay patterns by treating these states as (S)-wave
(\Sigma_c \bar{D}^{()}) configurations. The short-range transitions
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[
\Sigma_c...
We analyze the radiative decay $P_c(4457)(3/2^-) \to P_c(4312)(1/2^-)\gamma$ by treating both pentaquark states as $S$-wave hadronic molecules. Using a chiral unitary approach with heavy-quark spin symmetry, we calculate photon couplings to meson-baryon components via nineteen $M1$ triangle loops. The transition is dominated by the $\bar D^{*0}\to\bar D^{0}\gamma$ loop, yielding a pure $M1$...
The LHCb collaboration's discovery of pentaquarks has revitalized interest in heavy exotic baryon spectroscopy, motivating extensive searches for new states. In this work, we investigate hidden-charm pentaquark states in heavy meson and singly heavy baryon systems by employing an off-shell coupled-channel formalism. The interaction kernel is constructed from meson exchange diagrams using an...
We investigate vector-mesons production off the nucleon within a hybrid Regge approach based on effective Lagrangians. We simultaneously examine total and differential cross sections and spin-density matrix elements. Such measurements could be carried out in future high-intensity poin- and kaon-beam experiments at facilities such as J-PARC. The results of this study may help to shed light on...
We investigate the dynamical generation of isoscalar charmonium-like
states with a coupled-channel approach. Our focus is placed on states
with quantum numbers $J^{PC}=0^{++}$, $1^{++}$, $2^{++}$, and $3^{--}$
in the mass range of 3.6 to 4.3 GeV. We describe these systems through
effective Lagrangians constrained by heavy-quark spin-flavor and
chiral symmetries, employing an off-shell...
We present Proposal P111 for a new experiment that will investigate $J/\psi$ production in $\pi^-p$ reactions near threshold at the $\pi$20 beamline of J-PARC. Studying $J/\psi$ production in $\pi^−p$ collisions will offer valuable insights into the mechanism of $c\bar{c}$ pair creation in pion-induced reactions, with particular focus on hidden-charm pentaquark states. This measurement seeks...
We investigate low-energy $N\phi$ scattering driven by a pole-enhanced triangle-like diagram, in which the two-Kaon-exchange contribution is promoted by the near-threshold $\Lambda(1405)$ pole in the $N\bar K$ subsystem. Using an unphysical Kaon mass motivated by lattice simulations, we evaluate the $N\phi$ scattering length and find that this mechanism generates an attractive interaction with...
Near-threshold vector-meson photoproduction offers a promising way to investigate both exotic-hadron production and the internal structure of hadronic and nuclear targets. In particular, (J/\psi) photoproduction has attracted considerable attention as a possible channel for searching for hidden-charm pentaquark states and as a probe of the gravitational form factors of the proton. However, the...
The S-matrix describing the scattering process can be expressed in terms of projection operators onto the allowed spin–isospin channels and the corresponding phase shifts. Using the entanglement entropy in the spin or isospin space of the two-particle state, one can define the entanglement power, which quantifies the ability of the S-matrix to generate entanglement in the system. By...
The LHCb collaboration has observed a pentaquark system, $udsc\bar{c}$, with
$J^{\pi} = 1/2^{-}$, whose mass is $4338.2$ MeV with $\Gamma = 7$ MeV [1].
To describe this state, I use a constituent quark model, and the employed
Hamiltonian is based on Semay and Silvestre-Brac [2]. This Hamiltonian
reproduces all of the meson and baryon states which appear in the open channels
of this...
We investigate the three-body $PPV$ and $PVV$ systems, where $P$ denotes a pseudoscalar meson and $V$ denotes a vector meson. The Faddeev equations are solved within the fixed-center approximation, while the underlying two-body $PP$, $PV$ and $VV$ interactions are determined from the chiral unitary approach. Strong interactions among these mesons produce obvious resonance structures in the...
Interactions between a nucleon and a meson containing a heavy antiquark, in which quark-antiquark annihilation is absent, have been predicted to be attractive and to form genuine pentaquark states. With realistic lattice QCD simulations for such systems now feasible, first-principles determination of these interactions can provide theoretical prediction for the existence of the pentaquarks....
Recent advances in lattice QCD have enabled increasingly precise first-principles calculations of nucleon structure observables. In this talk, I will present recent progress on nucleon electromagnetic and axial form factors, together with flavor-diagonal nucleon charges, with particular emphasis on controlling excited-state contamination. I will discuss data-driven analyses guided by the...
The tensor form factors of the nucleon carry essential information for understanding its internal spin structure. The monopole tensor form factor at $Q^2=0$ is identified as the nucleon tensor charge, which corresponds to the first moment of the leading-twist transversity distribution $h_1(x)$. While transversity has been studied extensively both in theory and in experiment, the other tensor...
With 10 billion $J/\psi$ events collected at \mbox{BESIII}, the decay of $X(2370)\rightarrow K^{*}(892)^{0}\bar{K}^{0}+\mathrm{c.c.}$ is searched for via the $J/\psi\rightarrow\gamma K_{S}^{0}K_{S}^{0}\pi^{0}$ process. No evidence of this decay mode is found, with $\mathcal{B}[J/\psi\rightarrow\gamma X(2370)] \times \mathcal{B}[ X(2370) \rightarrow K^{*}(892)^{0}\bar{K}^{0}+\mathrm{c.c.}...
In this talk, the current research work on the scalar glueball gravitational form factors within the Skyrme-Faddeev model will be presented, where this model is constructed based on the Hopf topological invariant. Next, a comparison of our interesting findings with other theoretical calculations and lattice QCD simulation results will be presented and discussed.
We study a family of genuinely exotic five-flavor molecular pentaquark states containing the five quark flavors $u,d,s,c,b$ that form experimentally accessible hadrons. We construct the meson-baryon interaction from the local hidden gauge symmetry combined with heavy-quark spin symmetry, following the chiral unitary description that reproduces the LHCb hidden-charm strange pentaquarks....
Recently the LHCb collaboration observed five new narrow excited states in the $\bar{K}\Xi_c$ invariant mass spectrum: the $\Omega_c(3000)$, $\Omega_c(3050)$,$\Omega_c(3065)$, $\Omega_c(3090)$ and $\Omega_c(3119)$. Following this discovery, the Belle Collaboration confirmed four of these five narrow states. A popular interpretation is that the observed $\Omega_c^*$ states correspond to the...
The experimental observation of a number of excited charmed and bottom baryons has significantly enriched heavy-baryon spectroscopy and provides an important opportunity to study the nonperturbative dynamics of QCD. We classify the P-wave singly heavy baryons according to their flavor representations, internal orbital excitations, and the angular momenta of their light degrees of freedom....
We systematically investigate the spectrum and decay properties of charm-strange mesons using a chiral unitary approach that combines Weinberg-Tomozawa interactions with bare $c\bar{s}$ states from the constituent quark model. The S-wave interactions in the (S,I)=(1,0) sector produce a rich $D_{sJ}$ spectrum with $J^P$=$0^+$, $1^+$, $1^-$, $2^-$. In addition to the well-known $DK$ and $D^* K$...
Compositeness is an important concept to promote a quantitative understanding of the inner structure for a molecular state. We introduce the compositeness formalism for the case of the resonance, as a generalization of bound-state case. We have also proposed a more general form of two-body scattering amplitude with explicit inclusion of CDD pole, which is more widely applicable than the...
We study the $\Lambda \overline{\Lambda}$ and $\Lambda_c \overline{\Lambda}_c$ systems in a constituent quark model with color–color, color–spin, and three-quark interactions. The effective baryon–antibaryon interaction is obtained using a variational approach in a constituent quark model. Our results indicate that compact bound states are possible in both strange and charmed sectors, although...
Effective field theories (EFTs) are a popular theoretical method in hadron physics and few-body physics. By employing dibaryon fields (or dimer fields) for a two-nucleon system, one can expand the terms around the unitarity limit; the expanded terms are naturally matched to effective range parameters, and the dibaryon (dimer) fields are useful tools to describe bound and resonant states for a...
We investigate the electromagnetic form factors of the nucleon using
an effective chiral theory based on the QCD instanton vacuum.
Here we take into account the momentum-dependent dynamical quark mass
originating from the instanton-induced 2$N_f$ quark interactions.
The momentum-dependent quark mass naturally plays the role of a regulator,
so that no additional regularization is needed....
Understanding the complexities of hadron-hadron interactions, particularly in the strangeness sector, is crucial for both hadron physics and the study of dense nuclear matter. Traditionally, these interactions have been investigated through direct scattering experiments, which are inherently limited by the available beam and target channels. To overcome these limitations, two pioneering...
We study the $D^0\bar{D}^{*0}$ momentum correlation function to clarify the near-threshold structure of $X(3872)$. The $D\bar{D}^*$ interaction is described by a Yamaguchi-type separable potential that includes an effective contribution from a $c\bar{c}$ core. The parameters are fixed to reproduce the observed $X(3872)$ mass. When the pole lies extremely close to the $D^0\bar{D}^{*0}$...
We study the production of exotic hadrons in heavy-ion collisions, and argue the dependence of transverse momentum distributions and yields of exotic hadrons on their internal structures. Taking X(3872) and X(3915) mesons as examples, we not only discuss the centrality dependence of the yield on the internal structure of exotic hadrons in heavy ion collisions, but also investigate the...
With the development of interaction femtoscopy, interactions in various flavor systems are being revolutionized and clarified. In particular, the interaction between strange particles and nucleons provides a foundation for a systematic understanding of hadron interactions. On the other hand, femtoscopy typically suffers from the drawback that it is difficult to decompose spin and isospin...
The K1.8BR and K1.8 beam lines at the J-PARC Hadron Experimental Facility provide intense secondary kaon beams in the momentum region of approximately 0.6–2 GeV/c, offering unique opportunities to study strange-hadron spectroscopy and hadron interactions. At K1.8BR, the E72 experiment investigates the $K^-p$ reaction near the $\Lambda\eta$ threshold to clarify the threshold enhancement and...
The Λη threshold region is of particular interest for understanding the excitation spectrum of Λ hyperons. Previous measurements of the K−p → Λη reaction revealed a strongly non-uniform angular distribution near threshold. Since a J/P = 1/2− resonance is expected to produce a nearly isotropic angular distribution in this region, the observed behavior cannot be readily explained by the...
Kaonic nuclei are exotic few-body systems in which an antikaon is bound as a constituent particle. They provide a unique testing ground for the strongly attractive subthreshold $\bar{K}N$ interaction and the resulting few-body dynamics. In the J-PARC E15 experiment, the simplest candidate, the ''$K^-pp$'' state, was observed as a structure in the $\Lambda p$ invariant-mass spectrum of the...
Quantum Chromodynamics (QCD) has been firmly established as the fundamental theory of the strong interaction, and lattice QCD calculations have successfully bridged QCD and nuclear systems; however, the mechanism by which quarks build hadrons remains unresolved, particularly for excited states and exotic multiquark configurations that reflect the non-trivial dynamics of the low-energy QCD...
Nucleon resonances (N and Δ) have been studied for a long time mostly through
γN→πN. πN→πN, and γN→ππN reactions. However, there are many resonances which
have not been established experimentally, due to a limited number of πN→ππN reaction
data which was mainly measured in 1970’s. Thus, J-PARC E45 has been proposed to
study nucleon resonances in πN→ππN reactions with high-intensity π±...
Over the past seventy years, studies of the electromagnetic production of strangeness have evolved from pioneering photo- and electroproduction experiments into a powerful tool for investigating hadron structure and strong interactions. Early measurements established the foundation for understanding these reactions, while the continuous accumulation of experimental data stimulated the...
We present a discussion of the mass spectrum of strange and heavy baryons in nuclear matter, based on the framework of the pion mean-field approach. We will also discuss possible applications of the approach to strangeness-mixed nuclear matter.
In recent years, there has been growing interest in exotic hadrons that exhibit structures beyond the conventional hadron picture, where baryons are treated as three-quark states ($qqq$) and mesons as quark--antiquark pairs ($q\bar{q}$). In the charm sector, many exotic hadrons such as $XYZ$, $P_c$, and $T_{cc}$ particles have been reported in experiments. Most of these states have appeared...
We develop a non-perturbative approach to heavy-quark effective theory based on the instanton-induced heavy-light effective action. The formalism incorporates spontaneous chiral symmetry breaking and heavy-quark spin symmetry from the outset and is reformulated in terms of chirally rotated constituent light quarks interacting with Goldstone bosons. Heavy-meson states emerge dynamically as...
