The emergence of hadron mass (EHM) represents one of the most challenging and still open problem in the Standard Model. The recent advances toward understanding EHM from the experimental results on the evolution of the nucleon resonance electrocouplings with photon virtuality $Q^2$ available from exclusive meson electroproduction data measured with the CLAS detector at JLab will be presented...
A dynamical model has been developed, following the ANL-Osaka approach, to investigate the $J/\psi$ photo-production reaction on the nucleon. The photo-production mechanisms consists of the Pomeron-exchange and a phenomenological multi-gluon exchange calculated from Constituent quark model and $J/\psi$-$N$ potential deduced from LQCD. The final state interactions include the coupled-channel...
In the last decades a significant progress have been made in the electroproduction of nucleon resonances $N^\ast$. Form factors associated to the $\gamma^\ast N \to N^\ast$ transition, where $N$ is the nucleon, have been measured in different facilities, at low, intermediate, and large square momentum transfer, $Q^2$, for increasing values of the resonance mass. The new experimental data...
The Mainz Microtron MAMI is an ideal facility to study the hadron structure with the electromagnetic probe. High-intensity polarized electron and photon beams with energies up to 1.6 GeV are delivered to several experimental halls. Polarized targets and recoil polarimeters in combination with dedicated detectors are available for precision experiments in hadron physics.
Supplementary, the...
In this presentation, we will show experimental plans to study nucleon resonances ($N^*$ and $\Delta^*$) using $\pi N \rightarrow \pi \pi N$ reactions (E45) and search for new $\Lambda(1665)$ resonance in $K^{-} p \rightarrow \Lambda \eta$ reaction (E72) at J-PARC Hadron Experimental Facility. These experiments will be performed using a large acceptance spectrometer based on a Time Projection...
Data on the photo- and electroproduction of different hadrons provide access to the spectrum of excited baryons and its properties. Recent results from the Julich-Bonn-Washington model will be presented, including extensions to the electroproduction of pions and $\eta$ mesons, and to $K\Sigma$ photoproduction. The amplitudes and resonance properties obtained through this phenomenological...
The talk will summarize the newly-obtained knowledge about the spectrum of light baryons, which has been attained in recent years with the help of coupled-channel partial-wave analyses. Then, further details will be given on new results and methods for the single-channel amplitude analyses of reactions involving particles with spin, to which the author has contributed directly. An outlook will...
The interaction between an eta meson and a nucleus provides the in-medium modification of the eta meson and/or a chiral partner candidate of the nucleon $N(1535)1/2^-$, to which the eta meson and nucleon couples. We have studied such an interaction for the lightest nucleus, deuteron, from the measurement of cross sections for coherent neutral-pion and eta-meson photoproduction on the deuteron....
In the present work, we investigate the hidden-strangeness production process in the $S=+1$ channel via $K^+ p \to K^+ \phi p$, focusing on the exotic pentaquark molecular $K^* \Sigma$ bound-state, assigned by $P_s^+(2071,3/2^-)$. For this purpose, we employ the effective Lagrangian approach in the tree-level Born approximation. Using the experimental and theoretical inputs for the exotic...
We will report four-body study for tetraquarks of various flavor combinations including confining and scattering states. Properties of bound and resonant states are studied. Different structures of molecular or compact types emerge depending on how far the states are located from thresholds.
Refs: Q. Meng et al, Phys.Lett.B 814 (2021) 136095; Phys.Lett.B 824 (2022) 136800
"How does QCD build hadrons?" is still an unanswered question in hadron physics. In particular, behaviors of the strong interaction in low energy is an issue, which are characterized by the spontaneous breaking of chiral symmetry and quark confinement. As a consequence, massive, constituent quarks, as effective degrees of freedom to describe hadrons, are emergent together with the so-called...
A very important contribution of dilepton production in pion-nucleon collisions comes from the Dalitz decay of $s$-channel baryon resonances, $R \to N e^+ e^-$. These dileptons originate from a virtual photon with small timelike squared four-momentum $q^2$, therefore the study of this reaction gives access to the electromagnetic interaction of baryon resonances in a kinematical domain...
I will present several running or approved high luminosity experiments planned in Hall A. I will also discuss possible new experiment using improved version of those setups in particularly Double Deeply Virtual Compton Scattering.
The PANDA (Antiproton annihilations in Darmstadt) experiment at the Facility for Antiproton and Ion Research, FAIR, in Darmstadt, Germany, will address a variety of questions in hadron physics utilizing an antiproton beam of up to 15 GeV/c in momentum. The experiment is designed to work in the charmonium mass region, where recent experimental evidence found a plethora of states that are...
The discovery of the X, Y, Z meson states first by Belle, and the $P_C$ baryon states by LHCb revealed the existence of multi-quark objects beyond the simple quark-antiquark or 3-quark valence configurations in the (hidden) charm sector. If the emergence of such multi-quark structures was a general feature of QCD, then related structures should exhibit in the uds-sector as well. The BGOOD...
In search of the possibility of exotics/hybrid states, we present the Regge description of photoproduction of axial meson as well as tensor meson from the recombination of photoproduction with multi pion in the final state as a single-particle process. Comparative analyses with experimental data are provided for further guidance in the investigation of possible hybrids in these photoproductions.
We explore the link between the chiral symmetry of QCD and the numerical results of the light-front quark model, analyzing both the two-point and three-point functions of the pion. Including the axial-vector coupling as well as the pseudoscalar coupling in the light-front quark model, we discuss the implication of the chiral anomaly in describing the pion decay constant, the pion-photon...
Electron scattering data off a proton target has been measured with the CLAS12 spectrometer in Hall B at Jefferson Laboratory in a wide kinematic range covering $W$ up to 2.5 GeV and $Q^2$ up to 10 GeV$^2$. These results allow new opportunities to explore a wide range of physics including inclusive, semi-inclusive and fully exclusive reactions. Preliminary results aimed toward the extraction...
Multistrangeness baryons ($S < -1$) are important in our understanding of strong interactions and are expected to be observed more precisely in the future experiments, e.g., J-PARC, FAIR/GSI, and JLab. We investigate the reaction mechanism of $K^- p \to K \Xi$ based on the effective Lagrangian approach. In addition to the usual Born diagrams, the box diagrams are taken into account in detail....
We show recent results on excited hadrons at Belle (II) experiment. First, we discuss an observation of excited $S=-3$ hyperon ${\mathrm {\Omega } (2012) }^{-}$ and properties of $\Lambda(1670)$ and $\Sigma(1385)^+$ hyperons. In the analysis procedure, the importance of interplay between experiment and theory will be demonstrated. In addition, recent results on excited charmed baryons are...
Medium modifications on the distribution functions of the spin-1 vector meson as well as its medium properties are investigated in the quark-level chiral effective theory of QCD. Nuclear medium effects are also obtained from the same chiral effective model. Remarkable results on the distribution functions and properties of vector meson in the nuclear medium will be presented and discussed.
We perform a sensitivity study of an unbinned angular analysis of the $B\to D^*(D\pi)\ell\nu$ decay, including the contributions from the right-handed (R.H.) vector current. We show that the Wilson coefficient of the R.H. vector current can be strongly constrained by measuring the normalized angular observables $\langle g_i \rangle$ (i=1,2,...,11) without the intervention of the $V_{cb}$ puzzle.
The mechanical properties of the proton are encoded in the proton’s matrix element of the energy-momentum tensor (EMT), and are expressed in the gravitational form factors (GFF) that represent the distribution of mass, shear stress, and angular momentum inside the proton. Another global quantity that can be obtained is the mechanical radius of the proton. The GFF can be directly probed only...
Light-Front Quark Model (LFQM) based on the QCD motivated effective Hamiltonian provides a consistent framework for the analysis of both the mass spectra and the wave-function related physical observables such as decay constants and electromagnetic form factors of hadrons. I will review the framework of LFQM and focus on the recent application on the radially excited pseudoscalar and vector...
In this talk, I review a series of recent works on the structure of singly heavy baryons in a pion mean-field approach or the chiral quark-soliton model. In the infinitely heavy-quark mass limit, a singly heavy baryon can be viewed as a bound state of the soliton with $N_c-1$ light valence quarks and a heavy quark as a static color source. The presence of the $N_c-1$ valence quarks produces...
Understanding hadron spectrum emerging from QCD is one of the central issues in hadron physics. One of the challenging problems is to clarify the internal structure of the observed states whether they are conventional or exotic states. In this talk, I will review our recent activities to understand the excited states of hadron, including meson and baryon, within the chiral and light-front...
We investigate the masses and radii of neutron stars within the framework of the in-medium modified chiral soliton model, considering the effects of surrounding baryonic environment on the properties of in-medium baryons. The equation of state describing an infinite and asymmetric nuclear matter are obtained by introducing the density-dependent functions. To extrapolate the high density and...
We investigate meson resonances with quantum numbers $J^P=1^+$ and $S=0$ from the interaction of the pseudoscalar meson with the vector meson using the coupled-channel approach. Having included all possible one-meson exchange diagrams without an axial-vector meson one, we reproduce the experimental data on charge exchange reaction in $a_1$, $h_1$ and $b_1$ channels. This result exhibits the...
We investigate the transverse single-spin asymmetry (TSSA) for the very forward neutral pion production by employing the triple-Regge exchanges. The TSSA is ratio of spin-dependent and spin-averaged differential cross section. In the RHICf energy($\sqrt{s}=510\,\mathrm{GeV}$), the inclusive $p+p^\uparrow\to\pi^0+X$ process will be diffractive, so that $d\sigma$ can be expressed in terms of the...
We investigate the mass spectrum and electromagnetic transitions of charmonia, emphasizing the instanton effects on them. The heavy-quark potential consists of the Coulomb-like potential from one-gluon exchange and the linear confining potential. We introduce the nonperturbative heavy-quark potential derived from the instanton vacuum. We also consider the screened confining potential, which...
We investigate the gravitational form factors of the baryon octet within the framework of the chiral quark-soliton model, also known as the pion mean-field approach, emphasizing the effects of flavor SU(3) symmetry breaking on the form factors. The $D$-term form factors provide information on the stability conditions of the baryon octet in terms of the pressures and shear forces inside them....
In the present talk, we present the axial-vector transition form factors of the lowest-lying heavy baryons within the framework of the chiral quark-soliton model. In the infinitely heavy quark mass limit, a heavy quark can be considered as a color static source. We consider the linear rotational $1/N_{c}$ and strange current quark mass corrections. The results of axial-vector transition form...
The study of electromagnetic transitions opens a window into the very nature of the strong interaction. And, indeed, such a study of how a ground-state nucleon transitions to an excited state, over a broad range of $q^2$, will provide keen insight into the evolution of how dynamically-generated masses emerge from the asymptotically-free, nearly massless quarks of perturbative QCD as well as...
Hard exclusive pion production is a well-established tool for studying Generalized Parton Distributions (GPDs). During the last decade, extensive studies have been performed on hard exclusive 𝜋0 and 𝜋+ production off the proton. However, hard exclusive 𝜋− production off the proton is so far nearly unexplored. It can be described based on 𝑁→Δ++ transition GPDs, which can help us to gain...
The elastic $\alpha$-$^{12}$C scattering at low energies for $l=0,1,2,3,4,5,6$ is studied in effective field theory. We discuss a construction of the $S$ matrices of elastic $\alpha$-$^{12}$C scattering in terms of the amplitudes of sub-threshold bound and resonant states of $^{16}$O, which are calculated from the effective Lagrangian. Parameters appearing in the $S$ matrices are fitted to the...
Summary of the workshop and closing remarks
Recently, the 3D EMT form factors and their distributions for a spin-1 particle have been studied in various papers. However, to have true probabilistic distributions, one has to go to the infinite momentum frame instead of the 3D Breit frame. A price to pay is that the EMT distributions should be defined in the 2D space. In this talk, we first provide the model-independent formalism for the...
The N* program in Jefferson Lab is crucial for understanding the strong interaction in non-perturbative regime and the emergence of hadron mass. Studies of resonance electroexcitation in N$\pi$ electroproduction represent an important part of these efforts. The data on beam spin asymmetry provide unique information on the imaginary part of the interference terms between the electroproduction...
