Search

Recent high-precision $e^+e^-\to c\bar{c}$ data from the BESIII and Belle are highly useful to understand the vector charmonium pole structure and puzzling lineshapes due to the exotic hadron candidates $Y$. We thus conduct a global coupled-channel analysis of most of the available data (9 two-body, 9 three-body, and 1 four-body final states) in $\sqrt{s}=3.75-4.7$ GeV. Not only cross sections but also invariant mass distributions of subsystems are fitted. Our model includes dozens of (quasi) two-body states that nonperturbatively couple with each other through bare charmonium excitations and particle-exchange mechanisms required by the three-body unitarity. The amplitudes obtained from the fits are analytically continued to vector charmonium and $Z_c$ poles. We do not find a $\psi(4160)$ pole that has been considered well-established. Instead, we find two poles of $\sim 4230$ MeV; $\psi(4230)$ with $\Gamma= 36$ MeV and a broader one with $\Gamma= 114$ MeV. Two $Z_c$ poles are found as virtual states $\sim 40$ MeV below the $D^*\bar{D}^{(*)}$ thresholds, being consistent with lattice QCD results. This work presents the first global analysis to determine the vector charmonium and $Z_c$ poles, thereby paving the way to extracting detailed properties of the prominent exotic hadron candidates from data., Comment: 10 pages, 3 figures; (v2) pole uncertainties added, supplemental material added

Recent BESIII data on radiative $J/\psi$ decays from $\sim 10^{10}$ $J/\psi$ samples should significantly advance our understanding of the controversial nature of $\eta(1405/1475)$. This motivates us to develop a three-body unitary coupled-channel model for radiative $J/\psi$ decays to three-meson final states of any partial wave ($J^{PC}$). Basic building blocks of the model are bare resonance states such as $\eta(1405/1475)$ and $f_1(1420)$, and $\pi K$, $K\bar{K}$, and $\pi\eta$ two-body interactions that generate resonances such as $K^*(892)$, $K^*_0(700)$, and $a_0(980)$. This model reasonably fits $K_SK_S\pi^0$ Dalitz plot pseudo data generated from the BESIII's $J^{PC}=0^{-+}$ amplitude for $J/\psi\to\gamma K_SK_S\pi^0$. The experimental branching ratios of $\eta(1405/1475)\to\eta\pi\pi$ and $\eta(1405/1475)\to\gamma\rho$ relative to that of $\eta(1405/1475)\to K\bar{K}\pi$ are simultaneously fitted. Our $0^{-+}$ amplitude is analytically continued to find three poles, two of which correspond to $\eta(1405)$ on different Riemann sheets of the $K^*\bar{K}$ channel, and the third one for $\eta(1475)$. This is the first pole determination of $\eta(1405/1475)$ and, furthermore, the first-ever pole determination from analyzing experimental Dalitz plot distributions with a manifestly three-body unitary coupled-channel framework. Process-dependent $\eta\pi\pi$, $\gamma\pi^+\pi^-$, and $\pi\pi\pi$ lineshapes of $J/\psi\to\gamma(0^{-+})\to \gamma(\eta\pi\pi)$, $\gamma(\gamma\rho)$, and $\gamma(\pi\pi\pi)$ are predicted, and are in reasonable agreement with data. A triangle singularity is shown to play a crucial role to cause the large isospin violation of $J/\psi\to\gamma(\pi\pi\pi)$., Comment: 23 pages, 19 figures; (v2) minor changes, published version

Several $X$ and $Z_{cs}$ exotic hadrons were claimed in the LHCb's amplitude analysis on $B^+\to J/\psi \phi K^+$. The data shows that all the peaks and also dips in the spectra are located at thresholds of seemingly relevant meson-meson channels. While the LHCb analysis fitted the peaks with Breit-Wigner resonances, threshold kinematical cusps might be the cause of such structures. We thus analyze the LHCb data considering the threshold cusps. Our model is simultaneously fitted to $J/\psi \phi$, $J/\psi K^+$, and $K^+\phi$ invariant mass distributions. The threshold cusps fit well all the $X$, $Z_{cs}$, and dip structures. Our analysis indicates that spin-parity of the $X(4274)$ and $X(4500)$ structures are $0^-$ and $1^-$, respectively. This is different from the LHCb's spin-parity assignments ($1^+$ and $0^+$). The number of fitting parameters can be significantly reduced by considering the relevant threshold cusps. Our analysis shows that $D_s^{(*)}\bar{D}^{*}$ scattering lengths are consistent with zero. This disfavors an explanation of $Z_{cs}(4000)$ and $Z_{cs}(4220)$ as $D_s^{(*)}\bar{D}^{*}$ molecules, which is consistent with lattice QCD via the SU(3) relation., Comment: 5 pages, 2 figures, Contribution to the Proceedings for 20th International Conference on Hadron Spectroscopy and Structure (HADRON 2023), June 5 -9 2023, Genova, Italy

This document presents the initial scientific case for upgrading the Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab (JLab) to 22 GeV. It is the result of a community effort, incorporating insights from a series of workshops conducted between March 2022 and April 2023. With a track record of over 25 years in delivering the world's most intense and precise multi-GeV electron beams, CEBAF's potential for a higher energy upgrade presents a unique opportunity for an innovative nuclear physics program, which seamlessly integrates a rich historical background with a promising future. The proposed physics program encompass a diverse range of investigations centered around the nonperturbative dynamics inherent in hadron structure and the exploration of strongly interacting systems. It builds upon the exceptional capabilities of CEBAF in high-luminosity operations, the availability of existing or planned Hall equipment, and recent advancements in accelerator technology. The proposed program cover various scientific topics, including Hadron Spectroscopy, Partonic Structure and Spin, Hadronization and Transverse Momentum, Spatial Structure, Mechanical Properties, Form Factors and Emergent Hadron Mass, Hadron-Quark Transition, and Nuclear Dynamics at Extreme Conditions, as well as QCD Confinement and Fundamental Symmetries. Each topic highlights the key measurements achievable at a 22 GeV CEBAF accelerator. Furthermore, this document outlines the significant physics outcomes and unique aspects of these programs that distinguish them from other existing or planned facilities. In summary, this document provides an exciting rationale for the energy upgrade of CEBAF to 22 GeV, outlining the transformative scientific potential that lies within reach, and the remarkable opportunities it offers for advancing our understanding of hadron physics and related fundamental phenomena., Comment: Updates to the list of authors; Preprint number changed from theory to experiment; Updates to sections 4 and 6, including additional figures

The recent BESIII data on $J/\psi\to\gamma(K_SK_S\pi^0)$, which is significantly more precise than earlier $\eta(1405/1475)$-related data, enables quantitative discussions on $\eta(1405/1475)$ at the previously unreachable level. We conduct a three-body unitary coupled-channel analysis of experimental Monte-Carlo outputs for radiative $J/\psi$ decays via $\eta(1405/1475)$: $K_SK_S\pi^0$ Dalitz plot distributions from the BESIII, and branching ratios of $\gamma(\eta\pi^+\pi^-)$ and $\gamma(\gamma\pi^+\pi^-)$ final states relative to that of $\gamma(K\bar{K}\pi)$. Our model systematically considers (multi-)loop diagrams and an associated triangle singularity, which is critical in making excellent predictions on $\eta(1405/1475)\to \pi\pi\pi$ lineshapes and branching ratios. The $\eta(1405/1475)$ pole locations are revealed for the first time. Two poles for $\eta(1405)$ are found on different Riemann sheets of the $K^*\bar{K}$ channel, while one pole for $\eta(1475)$. The $\eta(1405/1475)$ states are described with two bare states dressed by continuum states. The lower bare state would be an excited $\eta^\prime$, while the higher one could be an excited $\eta^{(\prime)}$, hybrid, glueball, or their mixture. This work presents the first-ever pole determination based on a manifestly three-body unitary coupled-channel framework applied to experimental three-body final state distributions (Dalitz plots)., Comment: 7 pages, 6 figures; (v2) published version; statistical errors for eta(1405/1475) pole positions are added

First hidden-charm pentaquark candidate with strangeness, $P_{\psi s}^\Lambda(4338)$, was recently discovered in $B^-\to J/\psi\Lambda\bar{p}$ by the LHCb Collaboration. $P_{\psi s}^\Lambda(4338)$ shows up as a bump at the $\Xi_c\bar{D}$ threshold in the $J/\psi\Lambda$ invariant mass ($M_{J/\psi\Lambda}$) distribution. The $M_{J/\psi\Lambda}$ distribution also shows a large fluctuation at the $\Lambda_c\bar{D}_s$ threshold, hinting the existence of a possible $P_{\psi s}^\Lambda(4255)$. In this work, we determine the $P_{\psi s}^\Lambda(4338)$ and $P_{\psi s}^\Lambda(4255)$ pole positions for the first time. For this purpose, we fit a $B^-\to J/\psi\Lambda\bar{p}$ model to the $M_{J/\psi\Lambda}$, $M_{J/\psi\bar{p}}$, $M_{\Lambda\bar{p}}$, and $\cos\theta_{K^*}$ distributions from the LHCb simultaneously; $\chi^2/{\rm ndf}\sim 1.21$. Then we extract $P_{\psi s}^\Lambda$ poles from a unitary $\Xi_c\bar{D}$-$\Lambda_c\bar{D}_s$ coupled-channel scattering amplitude built in the model. In our default fit, the $P_{\psi s}^\Lambda(4338)$ pole is found at $( 4338.2\pm 1.4)-( 1.9\pm 0.5 )\,i$ MeV while the $P_{\psi s}^\Lambda(4255)$ pole at $4254.7\pm 0.4$ MeV. The $P_{\psi s}^\Lambda(4338)$ and $P_{\psi s}^\Lambda(4255)$ are mostly $\Xi_c \bar{D}$ bound and $\Lambda_c\bar{D}_s$ virtual states, respectively. Through our analysis, the data disfavors a hypothesis of $P_{\psi s}^\Lambda(4338)$ as merely a kinematical effect. This pole determination, which is important in its own right, sets a primary basis to study the nature of the $P_{\psi s}^\Lambda$ states., Comment: 8 pages, 5 figures, 3 tables; (v2) statistical errors of pole values corrected; (v3) efficiency-corrected and background-subtracted data are analyzed; a figure of Dalitz plot distribution added; (v4) published version

The recent LHCb data on $B_s^0\to J/\psi p\bar{p}$ revealed a new pentaquark-like $P_c(4337)^+$ structure, while finding no evidence for $P_c(4312)^+$ discovered earlier in $\Lambda_b^0\to J/\psi p K^-$. Though puzzling, the data actually offer an important hint to understand the nature of the pentaquark candidates. We develop a model to analyze the $B_s^0\to J/\psi p\bar{p}$ data. We find that a $\Sigma_c\bar{D}$ one-loop mechanism causes a threshold cusp that fits well the $P_c(4337)^+$ peak. Also, the $\Sigma_c\bar{D}$ and $\Lambda_c\bar{D}^{*}$ threshold cusps interfere with each other to reproduce an oscillating behavior in the proton helicity angle distribution. These results combined with our earlier analysis on $\Lambda_b^0\to J/\psi p K^-$ indicate that $P_c(4312)^+$ and $P_c(4337)^+$ are created by different interference patterns between the $\Sigma_c\bar{D}$ and $\Lambda_c\bar{D}^{*}$ (anomalous) threshold cusps. The proposed scenario consistently explains why the $P_c(4312)^+$ and $P_c(4337)^+$ peaks appear in $\Lambda_b^0\to J/\psi p K^-$ and $B_s^0\to J/\psi p\bar{p}$, respectively, but not vice versa or both., Comment: 7 pages, 4 figures; (v2) published version, title changed, one paragraph added in Sec. 2, references added

The determination of the Argonne National Laboratory-Osaka University (ANL-Osaka) Partial-Wave Amplitudes (PWA) of $\pi N$ and $\gamma N$ Reactions is reviewed. The predicted PWA are presented on a web page (https://www.phy.anl.gov/theory/research/anl-osaka-pwa). The formulas are given for using the predicted PWA to calculate the cross sections of (1) meson-baryon ($MB$) scattering $MB \rightarrow M'B'$ with $MB, M'B'= \pi N, \eta N, K\Lambda, K\Sigma$, (2) two-pion production $\pi N \rightarrow \pi\Delta, \rho N, \sigma N \rightarrow \pi\pi N$, (3) Meson photoproduction $\gamma N \rightarrow \pi N, \eta N, K\Lambda, K\Sigma$, (4) Pion electroproduction $N(e,e'\pi)N$, (5) inclusive $N(e,e')X$. We also present sample results from our fits to the data., Comment: 55 pages, 33 figures; minor typos corrected

The NuSTEC workshop (https://indico.cern.ch/event/727283) held at L'Aquila in October 2018 was devoted to neutrino-nucleus scattering in the kinematic region where hadronic systems with invariant masses above the $\Delta(1232)$ resonance are produced: the so-called shallow- and deep-inelastic scattering regime. Not only is the physics in this kinematic region quite intriguing, it is also important for current and future oscillation experiments with accelerator and atmospheric neutrinos. For the benefit of the community, links to the presentations are accompanied by annotations from the speakers., Comment: Proceedings of "NuSTEC workshop of Neutrino-Nucleus Scattering in the Shallow- and Deep-Inelastic Kinematic regime", GSSI, L'Aquila, Italy on October 11-13, 2018. 31 pages, 24 talk links

Photoproduction of the $\omega$ meson on the proton has been experimentally studied near the threshold. The total cross sections are determined at incident energies ranging from 1.09 to 1.15 GeV. The 1/2 and 3/2 spin-averaged scattering length $a_{\omega p}$ and effective range $r_{\omega p}$ between the $\omega$ meson and proton are estimated from the shape of the total cross section as a function of the incident photon energy: $a_{\omega p} = \left(-0.97^{+0.16_{\rm stat}}_{-0.16_{\rm stat}}{}^{+0.03_{\rm syst}}_{-0.00_{\rm syst}}\right)+i \left(0.07^{+0.15_{\rm stat}}_{-0.14_{\rm stat}}{}^{+0.17_{\rm syst}}_{-0.09_{\rm syst}}\right)$ fm and $r_{\omega p}=\left(+2.78^{+0.68_{\rm stat}}_{-0.54_{\rm stat}}{}^{+0.11_{\rm syst}}_{-0.13_{\rm syst}}\right)+i\left(-0.01^{+0.46_{\rm stat}}_{-0.50_{\rm stat}}{}^{+0.07_{\rm syst}}_{-0.00_{\rm syst}}\right)$ fm, resulting in a repulsive force. The real and imaginary parts for $a_{\omega p}$ and $r_{\omega p}$ are determined separately for the first time. A small $P$-wave contribution does not affect the obtained values., Comment: 6 pages, 4 figures

$Z_c(4430)$ discovered by the Belle and confirmed by the LHCb in $\bar{B}^0\to\psi(2S)K^-\pi^+$ is generally considered to be a charged charmonium-like state that includes minimally two quarks and two antiquarks. $Z_c(4200)$ found in $\bar{B}^0\to J/\psi K^-\pi^+$ by the Belle is also a good candidate of a charged charmonium-like state. We demonstrate that kinematical singularities in triangle loop diagrams induce a resonance-like behavior that can consistently explain the properties (mass, width, and Argand plot) of $Z_c(4430)$ and $Z_c(4200)$ from the experimental analyses. The triangle diagrams include only experimentally well-established hadrons. Applying this idea to $\Lambda_b^0\to J/\psi p\pi^-$, we also identify triangle singularities that behave like $Z_c(4200)$, but no triangle diagram is available for $Z_c(4430)$. This is consistent with the LHCb's finding that their description of the $\Lambda_b^0\to J/\psi p\pi^-$ data is significantly improved by including a $Z_c(4200)$ contribution while $Z_c(4430)$ seems to hardly contribute. Even though the proposed mechanisms have uncertainty in the absolute strengths which are currently difficult to estimate, they are certainly a compelling alternative to tetraquark-based interpretations of $Z_c(4430)$ and $Z_c(4200)$., Comment: 6 pages, 5 figures; published version; one figure on the cutoff-dependence added

We study $\eta$ photoproduction off the deuteron ($\gamma d\to\eta pn$) at a special kinematics: $\sim 0.94$ GeV of the photon beam energy and $\sim 0^\circ$ of the scattering angle of the proton. This kinematics is ideal to extract the low-energy $\eta$-nucleon scattering parameters such as $a_{\eta N}$ (scattering length) and $r_{\eta N}$ (effective range) because the $\eta$-nucleon elastic scattering is significantly enhanced. We show that if a ratio $R$, the $\gamma d\to\eta pn$ cross section divided by the $\gamma p\to\eta p$ cross section convoluted with the proton momentum distribution in the deuteron, is measured with 5% error, ${\rm Re}[a_{\eta N}]$ (${\rm Re}[r_{\eta N}]$) can be determined at the precision of $\sim\pm$0.1 fm ($\sim\pm$0.5 fm), significantly narrowing down the currently estimated range of the parameters. The measurement is ongoing at the Research Center for Electron Photon Science (ELPH), Tohoku University., Comment: 4 pages, 5 figures, Contribution to the Proceedings for 8th International Conference on Quarks and Nuclear Physics (QNP2018), November 13-17, 2018, Tsukuba, Japan

The current and near-future neutrino oscillation experiments require significantly improved neutrino-nucleus reaction models. Neutrino-nucleon pion production data play a crucial role to validate corresponding elementary amplitudes that go into such neutrino-nucleus models. Thus the currently available data extracted from charged-current neutrino-deuteron reaction data ($\nu_\mu d\to \mu^-\pi NN$) must be corrected for nuclear effects such as the Fermi motion and final state interactions (FSI). We study $\nu_\mu d\to \mu^-\pi NN$ with a theoretical model including the impulse mechanism supplemented by FSI from $NN$ and $\pi N$ rescatterings. An analysis of the spectator momentum distributions reveals that the FSI effects significantly reduce the spectra over the quasi-free peak region, and leads to a useful recipe to extract information of elementary $\nu_\mu N\to \mu^-\pi N$ processes using $\nu_\mu d\to \mu^-\pi NN$ data, with the important FSI corrections taken into account. We provide $\nu_\mu N\to \mu^-\pi N$ total cross sections by correcting the deuterium bubble chamber data for the FSI and Fermi motion. The results will bring a significant improvement on neutrino-nucleus reaction models for the near-future neutrino-oscillation experiments., Comment: 7 pages, 4 figures, supplemental material included as appendix, equations added, references added, published version

The study of pion production in nuclei is important for signal and background determinations in current and future neutrino oscillation experiments. The first step, however, is to understand the pion production reactions at the free nucleon level. We present an exhaustive study of the charged-current and neutral-current neutrino and antineutrino pion production off nucleons, paying a special attention to the angular distributions of the outgoing pion. We show, using general arguments, that parity violation and time-reversal odd correlations in the weak differential cross sections are generated from the interference between different contributions to the hadronic current that are not relatively real. Next, we present a detailed comparison of three, state of the art, microscopic models for electroweak pion production off nucleons, and we also confront their predictions with polarized electron data, as a test of the vector content of these models. We also illustrate the importance of carrying out a comprehensive test at the level of outgoing pion angular distributions, going beyond comparisons done for partially integrated cross sections, where model differences cancel to a certain extent. Finally, we observe that all charged and neutral current distributions show sizable anisotropies, and identify channels for which parity violating effects are clearly visible. Based on the above results, we conclude that the use of isotropic distributions for the pions in the center of mass of the final pion-nucleon system, as assumed by some of the Monte Carlo event generators, needs to be improved by incorporating the findings of microscopic calculations., Comment: 41 latex pages, 26 figures. Figure 4b corrected. Misprints corrected

The Argonne National Laboratory-Osaka University (ANL-Osaka) amplitudes (http://www.phy.anl.gov/theory/research/anl-osaka-pwa/) are applied to study pion photo-production reactions on the deuteron target. Within the multiple scattering formulation, we predict the cross sections of $d(\gamma,\pi)NN$ in the nucleon resonance region. The calculations include the impulse term and the final-state interaction (FSI) terms due to pion-exchange and nucleon-exchange. We show that the off-shell effects, calculated from the meson-exchange mechanisms, on the propagations of the exchanged nucleon and pion are significant in determining the reaction amplitudes. The FSI effects on the predicted cross sections are found to be important at energies near the $\Delta$(1232) resonance, and are still significant at higher energies. The results are in good agreement with most of the available data of $d(\gamma,\pi^0)np$ and $d(\gamma,\pi^-)pp$ reactions., Comment: 22 pages, 12 figures, title changed, website for ANL-Osaka amplitudes added, section for extracting neutron-target observables removed

We develop a reaction model for $\eta$ photoproduction off the deuteron ($\gamma d\to\eta pn$), and study the reaction at a special kinematics, where the photon beam energy is $\sim 0.94$ GeV and the scattered proton is detected at $\sim 0^\circ$, for the purpose of determining the $\eta$-nucleon scattering length ($a_{\eta N}$) and effective range ($r_{\eta N}$). In this kinematics, the $\eta$-nucleon elastic rescattering is significantly enhanced while other background mechanisms being suppressed. We show that a ratio $R$, the $\gamma d\to\eta pn$ cross section divided by the $\gamma p\to\eta p$ cross section convoluted with the proton momentum distribution in the deuteron, has a very good resolving power of $a_{\eta N}$ and $r_{\eta N}$. We conclude that the $R$ data with 5% error, binned in 1 MeV width of the $\eta$-neutron invariant mass, can determine ${\rm Re}[a_{\eta N}]$ (${\rm Re}[r_{\eta N}]$) at the precision of $\sim\pm$0.1 fm ($\sim\pm$0.5 fm), significantly narrowing down the previously estimated ranges of the parameters. To arrive at the conclusion, it is essential to use the $\gamma d\to\eta pn$ reaction model equipped with elementary amplitudes that are well constrained by $\pi N$ and $\gamma N$ reaction data through a sophisticated coupled-channels analysis. This result strongly motivates the Research Center for Electron Photon Science (ELPH) at Tohoku University to measure $R$., Comment: 6 pages, 6 figures, published version, 1 figure added, several references added, discussion on the previous works elaborated

We present our recent efforts to determine the matrix elements associated with the transition between the nucleon and a nucleon resonance induced by the vector current, which are necessary ingredients for models of neutrino-induced reactions in the resonance region. This is accomplished by making the comprehensive analysis of the data for various meson photo- and electro-production reactions off the nucleon within a sophisticated coupled-channels framework, which is known as the ANL-Osaka dynamical coupled-channels model. We also give a brief introduction to our project for constructing a unified neutrino reaction model conducted at the J-PARC Branch of the KEK Theory Center., Comment: 6 pages, 3 figures. Contribution to the proceedings of 18th International Workshop on Neutrino Factories and Future Neutrino Facilities Search (NuFact16), Quy Nhon, Vietnam, August 21-27, 2016

A precise description of neutrino-nucleus reactions will play a key role in addressing fundamental questions such as the leptonic CP violation and the neutrino mass hierarchy through analyzing data from next-generation neutrino oscillation experiments. The neutrino energy relevant to the neutrino-nucleus reactions spans a broad range and, accordingly, the dominant reaction mechanism varies across the energy region from quasi-elastic scattering through nucleon resonance excitations to deep inelastic scattering. This corresponds to transitions of the effective degree of freedom for theoretical description from nucleons through meson-baryon to quarks. The main purpose of this review is to report our recent efforts towards a unified description of the neutrino-nucleus reactions over the wide energy range; recent overall progress in the field is also sketched. Starting with an overview of the current status of neutrino-nucleus scattering experiments, we formulate the cross section to be commonly used for the reactions over all the energy regions. A description of the neutrino-nucleon reactions follows and, in particular, a dynamical coupled-channels model for meson productions in and beyond the $\Delta$(1232) region is discussed in detail. We then discuss the neutrino-nucleus reactions, putting emphasis on our theoretical approaches. We start the discussion with electroweak processes in few-nucleon systems studied with the correlated Gaussian method. Then we describe quasi-elastic scattering with nuclear spectral functions, and meson productions with a $\Delta$-hole model. Nuclear modifications of the parton distribution functions determined through a global analysis are also discussed. Finally, we discuss issues to be addressed for future developments., Comment: 68 pages, 33 figures; (v2) reference added, author name in metadata corrected; (v3) Discussion extended in Sec. I and IV, Fig. 10 added to compare with a previous result on two-pion productions, Table I extended to include a comparison with a recent T2K result on coherent pion production

By extending the dynamical coupled-channels analysis performed in our previous work [Phys. Rev. C 88, 035209 (2013)] to include the available data of photoproduction of pi meson off the neutron, the transition amplitudes for the photo-excitation of the neutron to nucleon resonances, gamma n --> N*, at the resonance pole positions are determined. The combined fits to the data for both the proton- and neutron-target reactions also revise our results for the resonance pole positions and the gamma p --> N* transition amplitudes. Our results allow an isospin decomposition of the gamma N --> N* transition amplitudes for the isospin I=1/2 N* resonances, which is necessary for testing hadron structure models and gives crucial inputs for constructing models of neutrino-induced reactions in the nucleon resonance region., Comment: 20 pages, 12 figures. Typos, equations, and numerical values in Tables are corrected

The maximum entropy method is examined as a new tool for solving the ill-posed inversion problem involved in the Lorentz integral transformation (LIT) method. As an example, we apply the method to the spin-dipole strength function of 4He. We show that the method can be successfully used for inversion of LIT, provided the LIT function is available with a sufficient accuracy., Comment: 5 pages, 2 figures. Poster presented by TM at the International Workshop on Neutrino-Nucleus Interaction in the Few-GeV Region (NuInt15), Novenber 16-21 2015, Osaka, Japan

A dynamical coupled-channels (DCC) model for neutrino-nucleon reactions in the resonance region is developed. Starting from the DCC model that we have previously developed through an analysis of $\pi N, \gamma N\to \pi N, \eta N, K\Lambda, K\Sigma$ reaction data for $W\le 2.1$ GeV, we extend the model of the vector current to $Q^2\le$ 3.0 (GeV/$c$)$^2$ by analyzing electron-induced reaction data for both proton and neutron targets. We derive axial-current matrix elements that are related to the $\pi N$ interactions of the DCC model through the Partially Conserved Axial Current (PCAC) relation. Consequently, the interference pattern between resonant and non-resonant amplitudes is uniquely determined. We calculate cross sections for neutrino-induced meson productions, and compare them with available data. Our result for the single-pion production reasonably agrees with the data. We also make a comparison with the double-pion production data. Our model is the first DCC model that can give the double-pion production cross sections in the resonance region. We also make comparison of our result with other existing models to reveal an importance of testing the models in the light of PCAC and electron reaction data. The DCC model developed here will be a useful input for constructing a neutrino-nucleus reaction model and a neutrino event generator for analyses of neutrino experiments., Comment: 38 pages, 52 figures, published version; minor modifications on v1

Resonance parameters (pole masses and residues) associated with the excited states of hyperons, Lambda^* and Sigma^*, are extracted within a dynamical coupled-channels model developed recently by us [Phys. Rev. C 90, 065204 (2014)] through a comprehensive partial-wave analysis of the K^- p --> barK N, pi Sigma, pi Lambda, eta Lambda, K Xi data up to invariant mass W = 2.1 GeV. We confirm the existence of resonances corresponding to most, if not all, of the four-star resonances rated by the Particle Data Group. We also find several new resonances, and in particular propose a possible existence of a new narrow J^P=3/2^+ Lambda resonance that couples strongly to the eta Lambda channel. The J^P=1/2^- Lambda resonances located below the barK N threshold are also discussed. Comparing our extracted pole masses with the ones from a recent analysis by the Kent State University group, some significant differences in the extracted resonance parameters are found, suggesting the need of more extensive and accurate data of K^- p reactions including polarization observables to eliminate such an analysis dependence of the resonance parameters. In addition, the determined large branching ratios of the decays of high-mass resonances to the pi Sigma^* and barK^* N channels also suggest the importance of the data of 2 --> 3 reactions such as K^- p --> pi pi Lambda and K^- p --> pi barK N. Experiments on measuring cross sections and polarization observables of these fundamental reactions are highly desirable at hadron beam facilities such as J-PARC for establishing the Lambda^* and Sigma^* spectrum., Comment: 25 pages, 8 figures. Version to appear in Physical Review C

We develop a dynamical coupled-channels model of K^- p reactions, aiming at extracting the parameters associated with hyperon resonances and providing the elementary antikaon-nucleon scattering amplitudes that can be used for investigating various phenomena in the strangeness sector such as the production of hypernuclei from kaon-nucleus reactions. The model consists of (a) meson-baryon (MB) potentials v_{M'B',MB} derived from the phenomenological SU(3) Lagrangian, and (b) vertex interactions Gamma_{MB,Y*} for describing the decays of the bare excited hyperon states (Y*) into MB states. The model is defined in a channel space spanned by the two-body barK N, pi Sigma, pi Lambda, eta Lambda, and K Xi states and also the three-body pi pi Lambda and pi barK N states that have the resonant pi Sigma* and barK* N components, respectively. The resulting coupled-channels scattering equations satisfy the multichannel unitarity conditions and account for the dynamical effects arising from the off-shell rescattering processes. The model parameters are determined by fitting the available data of the unpolarized and polarized observables of the K^- p --> barK N, pi Sigma, pi Lambda, eta Lambda, K Xi reactions in the energy region from the threshold to invariant mass W=2.1 GeV. Two models with equally good chi^2 fits to the data have been constructed. The partial-wave amplitudes obtained from the constructed models are compared with the results from a recent partial-wave analysis by the Kent State University group. We discuss the differences between these three analysis results. Our results at energies near the threshold suggest that the higher partial waves should be treated on the same footing as the S wave if one wants to understand the nature of Lambda(1405)1/2^- using the data below the barK N threshold, as will be provided by the J-PARC E31 experiment., Comment: 82 pages, 36 figures. Version to appear in Physical Review C. In this version some numerical errors are corrected, the partial wave analysis is extended to include the eta Lambda channel, and a number of references are added

Neutrino emissions from electron/positron capture on the deuteron and the nucleon-nucleon fusion processes in the surface region of a supernova core are studied. These weak processes are evaluated in the standard nuclear physics approach, which consists of one-nucleon and two-nucleon-exchange currents and nuclear wave functions generated by a high precision nucleon-nucleon potential. In addition to the cross sections for these processes involving the deuteron, we present neutrino emissivities due to these processes calculated for typical profiles of core-collapsed supernovae. These novel neutrino emissivities are compared with the standard neutrino emission mechanisms. We find that the neutrino emissivity due to the electron capture on the deuteron is comparable to that on the proton in the deuteron abundant region. The implications of the new channels involving deuterons for the supernova mechanism are discussed., Comment: 31 pages, 9 figures

We report our recent effort on the extraction of N*- and Delta*-resonance parameters (pole masses, coupling constants, etc.) through the comprehensive analysis of pion- and photon-induced pi N, eta N, K Lambda, and K Sigma production reactions. The analysis was performed with the ANL-Osaka dynamical coupled-channels approach, which satisfies the multichannel unitarity of the S-matrix in the channel space spanned by pi N, eta N, K Lambda, K Sigma, and also three-body pi pi N that contains rho N, pi Delta, and sigma N resonant components. Ongoing projects and future plans are also discussed., Comment: 5 pages, 4 figures. Contribution to the proceedings of 15th International Conference on Hadron Spectroscopy -- HADRON2013, November 4-8, 2013, Nara, Japan

Recent CLAS data for the pi Sigma invariant mass distributions (line-shapes) in the gamma p -> K^+ pi Sigma reaction are theoretically investigated. The line-shapes have peaks associated with the Lambda(1405) excitation. Our model consists of gauge invariant photo-production mechanisms, and the chiral unitary model that gives the rescattering amplitudes where Lambda(1405) is contained. It is found that, while the pi Sigma line-shape data in the Lambda(1405) region are successfully reproduced by our model for all the charge states, the production mechanism is not so simple that we need to introduce parameters associated with short-range dynamics to fit the data. Our detailed analysis suggests that the nonresonant background contribution is not negligible, and its sizable effect shifts the Lambda(1405) peak position by several MeV. We also analyze the data using a Breit-Wigner amplitudes instead of those from the chiral unitary model. We find that the fitted Breit-Wigner parameters are closer to the higher pole position for Lambda(1405) of the chiral unitary model. This work sets a starting point for a fuller analysis in which line-shape as well as K^+ angular distribution data are simultaneously analyzed for extracting Lambda(1405) pole(s)., Comment: 27 pages, 23 figures; published version, 4 figures added, some discussions added, typos corrected

We study neutrino-induced meson productions off the nucleon in the forward limit by applying the PCAC hypothesis to our dynamical coupled-channels (DCC) model. The DCC model reasonably describes pi N, gamma N -> pi N, eta N, K Lambda, K Sigma data in the resonance region. We give a prediction for nu N -> pi N, pi pi N, eta N, K Lambda, K Sigma$ reactions cross sections. We compare our results with those from the Rein-Sehgal model, and find a significant difference., Comment: 4 pages, 3 figures, Contribution to the proceedings of International Workshop on Neutrino Factories, Super Beams and Beta Beams (NUFACT 2013), August 19-24 2013, Beijing, China

The nucleon resonances are investigated within a dynamical coupled-channels model of pi N and gamma N reactions up to the invariant mass W = 2 GeV. The meson-baryon (MB) channels included in the calculations are MB = pi N, eta N, K Lambda, K Sigma, and pi pi N that has pi Delta, rho N, and sigma N resonant components. The meson-baryon amplitudes T_{M'B',MB}(W) are calculated from solving a set of coupled-channels integral equations defined by an interaction Hamiltonian consisting of (a) meson-exchange interactions v_{M'B',MB} derived from phenomenological Lagrangian, and (b) vertex interactions N* --> MB for describing the transition of a bare excited nucleon state N* to a channel MB. The parameters of v_{M'B',MB} are mainly constrained by the fit to the data of pi N --> pi N in the low energy region up to W =1.4 GeV. The bare masses of N* and the N* --> MB parameters are then determined in simultaneous fits to the data of pi N --> pi N up to W =2.3 GeV and those of pi N --> eta N, K Lambda, K Sigma and gamma N --> pi N, eta N, K Lambda, K Sigma up to W = 2.1 GeV. The pole positions and residues of nucleon resonances are extracted by analytically continuing the meson-baryon amplitudes T_{M'B',MB}(W) to the complex Riemann energy surface. From the extracted residues, we have determined the N* --> pi N, gamma N, eta N, K Lambda, K Sigma transition amplitudes at resonance poles. We compare the resonance pole positions from our analysis with those given by Particle Data Group and the recent coupled-channels analyses by the Juelich and Bonn-Gatchina groups. Four results agree well only for the first N* in each spin-parity-isospin (J^P,I) channel. For higher mass states, the number of states and their resonance positions from four results do not agree well. We discuss the possible sources of the discrepancies and the need of additional data from new hadron facilities such as J-PARC., Comment: 83 pages, 47 figures. Typos are corrected and references are added. Version to appear in PRC

Next generation neutrino oscillation experiments will need a quantitative understanding of neutrino-nucleus interaction far better than ever. Kinematics covered by the relevant neutrino-nucleus interaction spans wide region, from the quasi-elastic, through the resonance region, to the deeply inelastic scattering region. The neutrino-nucleus interaction in each region has quite different characteristics. Obviously, it is essential to combine different expertise to construct a unified model that covers all the kinematical region of the neutrino-nucleus interaction. Recently, several experimentalists and theorists got together to form a collaboration to tackle this problem. In this contribution, we report the collaboration's recent activity and a goal in near future., Comment: 4 pages, 3 figures, Contribution to the proceedings of 8th International Workshop on Neutrino-Nucleus Interactions in the Few-GeV Region (NuInt12), October 22-27 2012, Rio de Janeiro, Brazil

We study forward neutrino-induced meson production off the nucleon in the resonance region. Our calculation is based on a dynamical coupled-channels (DCC) model that reasonably describes pi (gamma) N -> pi N, eta N, K Lambda, K Sigma data in the resonance region. We apply the PCAC hypothesis to the DCC model to relate the pi N reaction amplitude to the forward neutrino reaction amplitude. In this way, we give a prediction for nu N -> pi N, pi pi N, eta N, K Lambda, K Sigma reaction cross sections. The predicted nu N -> pi pi N, eta N, K Lambda, K Sigma cross sections are, for the first time, based on a model extensively tested by data. We compare our results with those from the Rein-Sehgal model that has been very often used in the existing Monte Carlo simulators for neutrino experiments. We find a significant difference between them., Comment: 5 pages, 4 figures, Contribution to the proceedings of 8th International Workshop on Neutrino-Nucleus Interactions in the Few-GeV Region (NuInt12)

We have investigated the model dependence of meson resonance properties extracted from the Dalitz-plot analysis of the three-pions photoproduction reactions on the nucleon. Within a unitary model developed in Phys. Rev. D 84, 114019 (2011), we generate Dalitz-plot distributions as data to perform an isobar model fit that is similar to most of the previous analyses of three-pion production reactions. It is found that the resonance positions from the two models agree well when both fit the data accurately, except for the resonance poles near branch points. The residues of the resonant amplitudes extracted from the two models and by the usual Breit-Wigner procedure agree well only for the isolated resonances with narrow widths. For overlapping resonances, most of the extracted residues could be drastically different. Our results suggest that even with high precision data, the resonance extraction should be based on models within which the amplitude parametrization is constrained by three-particle unitarity condition., Comment: 17 pages, 12 figures, minor modifications on text and 2 figures, published version

As a first step toward developing a reaction model that enables a comprehensive description of neutrino-nucleon reactions in the nucleon resonance region, we have applied for the first time a dynamical coupled-channels model, which successfully describes \pi N, \gamma N --> \pi N, \eta N, \pi \pi N, K\Lambda, K\Sigma reactions up to W = 2 GeV, to predict the neutrino-induced meson-production reactions with \Delta S = 0 at the forward angle limit. This has been achieved by relating the divergence of the axial-current matrix elements at Q^2 = 0 to the \pi N --> X reaction amplitudes through the PCAC hypothesis. We present the contributions from each of the \pi N, \eta N, \pi \pi N, K\Lambda, K\Sigma channels to the F_2 structure function at Q^2 --> 0 limit up to W = 2 GeV., Comment: 9 pages, 3 figures

A unitary coupled-channels model is presented for investigating the decays of heavy mesons and excited meson states into three light pseudoscalar mesons. The model accounts for the three-mesons final state interactions in the decay processes, as required by both the three-body and two-body unitarity conditions. In the absence of the Z-diagram mechanisms that are necessary consequences of the three-body unitarity, our decay amplitudes are reduced to a form similar to those used in the so-called isobar-model analysis. We apply our coupled-channels model to the three-pions decays of a1(1260), pi2(1670), pi2(2100), and D0 mesons, and show that the Z-diagram mechanisms can contribute to the calculated Dalitz plot distributions by as much as 30% in magnitudes in the regions where f0(600), rho(770), and f2(1270) dominate the distributions. Also, by fitting to the same Dalitz plot distributions, we demonstrate that the decay amplitudes obtained with the unitary model and the isobar model can be rather different, particularly in the phase that plays a crucial role in extracting the CKM CP-violating phase from the data of B meson decays. Our results indicate that the commonly used isobar model analysis must be extended to account for the final state interactions required by the three-body unitarity to reanalyze the three-mesons decays of heavy mesons, thereby exploring hybrid or exotic mesons, and signatures of physics beyond the standard model., Comment: 32 pages, 10 figures. Version to appear in PRD

We study the stability of resonance poles in pi-N P_11 partial wave, particularly the Roper resonance, by varying parameters significantly within the EBAC dynamical coupled-channels model, keeping a good fit to the empirical amplitude. We find that two Roper poles are stable against the variation. However, for higher energies, the number of poles can change depending on how the parameters are fitted within error bars. We also developed a model with a bare nucleon which forms the physical nucleon by being dressed by the meson-cloud. We still find a good stability of the Roper poles., Comment: 4 pages, 2 figures, one minor correction, Contribution to the proceedings of the 8th International Workshop on the Physics of Excited Nucleons (NSTAR2011), Newport News, VA, USA, May 17-20, 2011

We address a question about how much resonance poles and residues extracted from data depend on a model used for the extraction, and on the precision of data. We focus on the P11 pi-N scattering and use the dynamical coupled-channel (DCC) model developed in Excited Baryon Analysis Center (EBAC) at JLab. We examine the model-dependence of the poles by varying parameters largely within the EBAC-DCC model. We find that two poles associated with the Roper resonance are fairly stable against the variation. We also study the stability of the Roper poles against different analytic structure of the P11 amplitude below pi-N threshold by using a bare nucleon model. We again find a good stability of the Roper poles., Comment: 4 pages, 4 figures, Contribution to the proceedings of 12th International Conference on Meson-Nucleon Physics and the Structure of the Nucleon (MENU2010), Williamsburg, USA, May 31-June 4 2010

An important question about resonance extraction is how much resonance poles and residues extracted from data depend on a model used for the extraction, and on the precision of data. We address this question with the dynamical coupled-channel (DCC) model developed in Excited Baryon Analysis Center (EBAC) at JLab. We focus on the P11 pi-N scattering. We examine the model-dependence of the poles by varying parameters to a large extent within the EBAC-DCC model. We find that two poles associated with the Roper resonance are fairly stable against the variation. We also develop a model with a bare nucleon, thereby examining the stability of the Roper poles against different analytic structure of the P11 amplitude below pi-N threshold. We again find a good stability of the Roper poles., Comment: 6 pages, 8 figures, Contribution to the proceedings of 24th International Nuclear Physics Conference (INPC), Vancouver, Canada, 4-9 July 2010

We show that two P11 nucleon resonance poles near the pi Delta threshold, obtained in several analyses, are stable against large variations of parameters within a dynamical coupled-channels analysis based on meson-exchange mechanisms. By also performing an analysis based on a model with a bare nucleon state, we find that this two-pole structure is insensitive to the analytic structure of the amplitude in the region below pi N threshold. Our results are M_pole = (1363^{+9}_{-6} -i79^{+3}_{-5}) MeV and (1373^{+12}_{-10} -i114^{+14}_{-9}) MeV. We also demonstrate that the number of poles in the 1.5 GeV < W < 2 GeV region could be more than one, depending on how the structure of the single-energy solution of SAID is fitted. For three-pole solutions, our best estimated result of a pole near N(1710) listed by Particle Data Group is (1829^{+131}_{-65} -i192^{+88}_{-110}) MeV which is close to the results of several previous analyses. Our results indicate the need of more accurate pi N reaction data in the W > 1.6 GeV region for high precision resonance extractions., Comment: 15 pages, 4 figures

We study coherent pion production in neutrino-nucleus scattering in the energy region relevant to neutrino oscillation experiments of current interest. Our approach is based on a combined use of the Sato-Lee model of electroweak pion production on a nucleon and the Delta-hole model of pion-nucleus reactions. Thus we develop a model which describes pion-nucleus scattering and electroweak coherent pion production in a unified manner. Numerical calculations are carried out for the case of the 12C target. All the free parameters in our model are fixed by fitting to both total and elastic differential cross sections for pi-12C scattering. Then we demonstrate the reliability of our approach by confronting our prediction for the coherent pion photo-productions with data. Finally, we calculate total and differential cross sections for neutrino-induced coherent pion production, and some of the results are (will be) compared with the recent (forthcoming) data from K2K, SciBooNE and MiniBooNE. We also study effect of the non-locality of the Delta-propagation in the nucleus, and compare the elementary amplitudes used in different microscopic calculations., Comment: 42 pages, 21 figures

We have developed a dynamical model for a unified description of the pion-nucleus scattering and photo- and neutrino-induced coherent pion production on nuclei. Our approach is based on a combined use of the Sato-Lee model for the electroweak pion production on a single nucleon and the Delta-hole model of pion-nucleus scattering. Numerical calculations are carried out for the case of the C12 target. After testing our model with the use of the pion photo-production data, we confront our predictions of the neutrino-induced coherent pion production reactions with the recent data from K2K and MiniBooNE., Comment: 6 pages, 6 figures, Contribution to the proceedings of NUINT2009 (6th International Workshop on Neutrino-Nucleus Interactions in the Few-GeV Region), May 18-22, 2009, Sitges, Barcelona, Spain

We examine a potential role of the neutrino deuteron reactions in the mechanism of supernova explosion by evaluating the energy transfer cross section for the neutrino heating. We calculate the energy loss rate due to the neutrino absorptions through the charged-current process as well as the neutrino scattering through the neutral-current process. In so doing, we adopt a detailed evaluation of cross sections for the neutrino deuteron reactions with the phenomenological Lagrangian approach. We find the energy transfer cross section for the deuteron is larger than those for $^{3}$H, $^{3}$He and $^{4}$He for neutrino temperatures (T$_\nu$ $\sim 4$ MeV) relevant to supernova core. Because of the low energy threshold for the deuteron breakup, the energy transfer rate rapidly increases from low temperature, T$_\nu$ $\sim 1$ MeV. This suggests that the neutrino deuteron reactions may contribute effectively to the heating mechanism during the dissociation of irons into light elements and nucleons in the shocked material of supernova core., Comment: 11 pages, 4 figures

We study coherent pion production in neutrino-nucleus scattering in the energy region relevant to the recent neutrino oscillation experiments. Our approach is based on the combined use of the Sato-Lee model and the Delta-hole model. Our initial numerical results are compared with the recent data from K2K and SciBooNE., Comment: 3 pages, 2 figures, To appear in the proceedings of the 18th Particle and Nuclei International Conference (PANIC08), Eilat, Israel, 9-14 Nov 2008; acknowledgment added