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Daisuke Jido

Publications and source records attributed to Daisuke Jido.

At least 19 recordsLinked to original sources
arXiv2026

Estimation of potential radius based on momentum distribution of a constituent particle

We propose using the potential radius as a probe of the structure of hadrons, particularly to classify exotic hadrons as hadronic or quark composite states.In this study, we focus on the radius of the effective potential felt by each constituent particle. Using a simple model with a square-well potential, we demonstrate that the potential radius can be estimated from the momentum distribution of a constituent particle not only for deeply bound states but also for shallowly bound states.We find that the momentum-based quantity provides a more robust estimate of the potential radius in the shallow-binding regime.This is because the momentum-based length scale decreases to zero as the potential radius vanishes, whereas the RMS radius approaches a finite value set by the binding energy.As a result, the momentum distribution avoids the finite-intercept problem that can make the inverse estimate of the potential radius ill-defined.With future experimental data on the momentum distribution of the constituent nucleon in $\overline{K}NNN$ production at J-PARC, the potential radius may be determined within the present framework.

nucl-th↗
arXiv2026

Hyperon-nucleon interaction through the $K^-d\to\pi\Lambda N$ reaction

The hyperon-nucleon interaction is investigated through the final-state interaction in the $K^-d\to\pi^-\Lambda p$ reaction. We focus on the $\Lambda N$-$\Sigma N$ coupled-channel interaction, which produces characteristic structures around the $\Sigma N$ thresholds in the $\Lambda p$ invariant mass spectrum. The spin-triplet $\Sigma N\to\Lambda p$ conversion amplitude is constructed within the $K$-matrix formalism using scattering lengths in the isospin basis. We first examine the dependence of the conversion amplitude on the $\Sigma N$ scattering lengths and find that the threshold structure is particularly sensitive to the sign of the real part of the $I=1/2$ scattering length. We then calculate the $\Lambda p$ invariant mass spectrum of the $K^-d\to\pi^-\Lambda p$ reaction, including the contributions from the background diagrams. The resulting spectra show characteristic structures around the $\Sigma N$ thresholds, whose shapes depend on the choice of the interaction parameters. These results suggest that the $\Lambda p$ invariant mass spectrum can serve as a useful observable for constraining the $\Lambda N$-$\Sigma N$ coupled-channel interaction.

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arXiv2025

Isotone Chain Study of $\bar{p}$-atom spectroscopy and Strong Spin-orbit splittings

Antiprotonic atoms have served as a pivotal tool for investigating the properties of baryon-baryon interactions, including their spin dependence. Examining the spin-orbit splittings induced by their strong interactions also could help clarify the nature of the $\bar{p}$-nucleus interactions and their fraction mediated by scalar and vector mesons. Although the strong spin-orbit splittings for a certain nucleus have been observed experimentally, thorough theoretical investigations have not yet been conducted. In this study, theoretical calculations based on the Dirac equation are systematically performed for nuclei along several isotone ``chains''. As a result, it is found that the magnitude of the strong spin-orbit splittings exhibits a significant dependence not only on the corresponding level shifts and widths almost linearly, but also on whether the optical potential enters as a vector or scalar potential. A simple perturbative analysis indicates that the relativistic corrections have a dominant effect the magnitude of the splittings. These results are expected to provide deeper insights into $\bar{p}$-nucleus interactions, and by extension baryon-baryon interactions, as well as into the properties of the mesons that mediate them.

hep-ph↗
arXiv2025

Pion properties in isospin-asymmetric nuclear matter using in-medium chiral perturbation theory

We compute the density dependence of in-medium pion properties, such as mass, wave function renormalization, and decay constant in the correlation function approach, and how they change under the influence of isospin-asymmetric nuclear matter. To this end, we use in-medium chiral perturbation theory to compute the relevant Feynman diagrams up to two-loop diagrams. Our results show that the isospin asymmetry of the nuclear matter splits these quantities into three separate values, corresponding to the three pions. Consequently, the tendency of each in-medium pion mass, wave function renormalization, and decay constant is dependent on the density and the neutron-to-proton ratio $\rho_n/\rho_p$ of nuclear matter. We also derive an in-medium Gell-Mann--Oakes--Renner relation which is valid for isospin-asymmetric nuclear matter and investigate to what extent it holds within our calculations.

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arXiv2025

Different scenarios of dynamical chiral symmetry breaking in the interacting instanton liquid model via flavor symmetry breaking

We investigate a type of dynamical chiral symmetry breaking (D$\chi$SB) for various current quark masses using the interacting instanton liquid model. The type of D$\chi$SB is classified based on the sign of the second derivative of the free energy density with respect to the quark condensate at the origin. We perform numerical simulations of the interacting instanton liquid model with the flavor SU(2) symmetric and (2+1)-flavor quarks. We find that the curvature is negative in the SU(2) case. This means the ordinary type of D$\chi$SB. In contrast, in the (2+1)-flavor case, a positive curvature is observed when the strange quark mass is as small as those of the up and down quarks. This suggests that the anomaly-driven type of D$\chi$SB can occur under the approximate flavor SU(3) symmetry. As the strange quark mass increases, the curvature gradually decreases and becomes negative when the strange quark mass is approximately three times larger than those of the light quarks. This difference can be understood in terms of the 't Hooft vertex which induces a six-quark interaction in the $N_f=3$ case and does a four-quark interaction in the $N_f=2$ case. Our results might indicate that the ratio between the strange and light quark masses plays a crucial role in understanding the microscopic relationship between D$\chi$SB and the anomaly effect.

hep-ph↗
arXiv2025

Theoretical study of the $\Sigma N$ cusp in the $K^-d\rightarrow\pi\Lambda N$ reaction

The $K^-d\rightarrow\pi\Lambda N$ reaction is useful for exploring the hyperon-nucleon interaction through final state interactions. In particular, the cusp structure of the $\Lambda N$ invariant mass spectrum at the $\Sigma N$ threshold contains information about the s-wave interaction of 1/2-isospin hyperon-nucleon systems. The calculation of the spectrum is performed with the aim of extracting the scattering length of the $\Sigma N(I=1/2)$ channel that couples to the $\Lambda N$ channel from this reaction, and the results are discussed in comparison with experimental data to highlight the factors that should be considered.

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arXiv2024

Possible scenario of dynamical chiral symmetry breaking in the instanton liquid

Based on simulations of the interacting instanton liquid model (IILM) with three-flavor quarks, we compute the free energy density of the QCD vacuum as a function of the quark condensate. We then evaluate the second derivative of the free energy density with respect to the quark condensate at the origin. This evaluation allows us to investigate whether chiral symmetry breaking in the IILM occurs in an anomaly-driven way. Such a breaking pattern of chiral symmetry has been proposed in a previous study to connect the QCD vacuum structure with meson properties, such as the mass of the sigma meson. We also perform the quenched simulations, in which no dynamical quarks interact with instantons. Comparing these results with the full calculations provides a better understanding of the pattern of chiral symmetry breaking in the IILM. We find that in the full IILM, chiral symmetry is dynamically broken in anomaly-driven way, whereas in the quenched IILM, it is broken through the ordinary mechanism. Based on these results, we suggest that chiral symmetry breaking in real QCD could also occur in an anomaly-driven way. Consequently, in phenomena where chiral symmetry breaking plays a crucial role, the anomaly effect may also have significant influence.

hep-ph↗
arXiv2024

Interrelation between $\bar{p}$-Ca Atom Spectra and Nuclear Density Profiles

This work studies $\bar{p}$-Ca atom spectra in light of the strong shifts and level widths, using the optical model with several types of parametric coefficients. The spectroscopic quantities are obtained as the eigenvalues of the Dirac equation, where the nuclear densities computed via nuclear Density Functional Theory and the effect of the anomalous magnetic moment are incorporated. The results indicate that the isovector term's contribution to the optical potential is crucial for explaining the systematical differences in the strong shifts between $^{40}$Ca and $^{48}$Ca. Furthermore, it is found that both the strong shifts and the level widths exhibit significant dependence on the nuclear density profiles. These findings provide critical insights into the nuclear structures, particularly in the context of Calcium isotopes, by offering a more comprehensive understanding of the underlying nuclear-hadron properties.

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arXiv2024

$K^-d\rightarrow\pi\Lambda N$ reaction with in-flight kaons for studying the $\Lambda N$ interaction

The $\Lambda N$ invariant mass spectra for the reactions $K^-d\rightarrow\pi^-\Lambda p$ and $K^-d\rightarrow\pi^0\Lambda n$ are calculated for experimental study of isospin symmetry breaking in the $\Lambda N$ scattering at low energies, the difference in the scattering lengths and effective ranges of $\Lambda p$ and $\Lambda n$ systems. The calculations are performed for in-flight kaons with a momentum of 1000 MeV/c with employing partial wave analysis up to the p-wave for meson-baryon amplitudes and the spin-flip term for baryon-baryon amplitudes. Kinematic selection is utilized to suppress the background processes by selecting forward-emitting pions and higher momentum nucleons. It is worth noting that isospin symmetry breaking in the $\Lambda N$ system can be extracted from the difference of the $\Lambda N$ invariant mass spectra between the $K^-d\rightarrow\pi^-\Lambda p$ and $K^-d\rightarrow\pi^0\Lambda n$ reactions.

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arXiv2024

A Possible Solution to the Difficulty in the Interpretation of Deuteron Compositeness

We study the theoretical structure of compositeness with explicit energy dependence, and find a possible explanation for the difficulty in the interpretation of compositeness of deuteron. Compositeness of deuteron is calculated as larger than one in many methods like weak-binding limit. Even though it is widely assumed that the energy dependence in interaction always comes from other states, which we call surjective interpretation, we find that the outcome of deuteron may suggest a violation of surjective interpretation. We directly perform numerical and perturbative calculations of deuteron compositeness. It is concluded that if the energy dependent part of interaction contributes to attraction, compositeness is likely to be enhanced from unity. We discuss the indications of this outcome and the model dependence of compositeness. We propose a straightforward extension and a thorough revise on the formalism of compositeness with field theory considerations.

hep-ph↗
arXiv2024

$K^+ N$ elastic scatterings for estimation of in-medium quark condensate with strange quarks

We revisit the low-energy $K^+N$ elastic scatterings in the context of the in-medium quark condensate with strange quarks. The chiral ward identity connects the in-medium quark condensate to the soft limit value of the pseudoscalar correlation function evaluated in nuclear matter. The in-medium correlation function of the psuedoscalar fields with strangeness describes in-medium kaon propagation and is obtained by kaon-nucleon scattering amplitudes in the low density approximation. We construct the kaon-nucleon scattering amplitudes in chiral perturbation theory up to the next-to-leading order and add some terms of the next-to-next-to-leading order with the strange quark mass to improve expansion of the strange quark sector. We also consider the effect of a possible broad resonance state around $P_\mathrm{lab} = 600$ MeV/c for $I=0$ reported in the previous study. The low energy constants are determined by existent $K^+N$ scattering data. We obtain good reproduction of the $K^+p$ scattering amplitude by chiral perturbation theory, while the description of the $KN$ amplitude with $I=0$ is not so satisfactory due to the lack of low energy data. Performing analytic continuation of the scattering amplitudes obtained by chiral perturbation theory to the soft limit, we estimate the in-medium strange quark condensate.

hep-ph↗
arXiv2024

Possible scenario of dynamical chiral symmetry breaking in the interacting instanton liquid model

We compute the vacuum energy density as a function of the quark condensate in the interacting instanton liquid model (IILM) and examine the pattern of dynamical chiral symmetry breaking from its behavior around the origin. This evaluation is performed by using simulation results of the IILM. We find that chiral symmetry is broken in the U(1)_A anomaly assisted way in the IILM with three-flavor dynamical quarks. We call such a symmetry breaking the anomaly-driven breaking which is one of the scenarios of chiral symmetry breaking proposed in the context of the chiral effective theories. We also find that the instanton-quark interaction included in the IILM plays a crucial role for the anomaly-driven breaking by comparing the full and the quenched IILM calculations.

hep-ph↗
arXiv2024

Search for {Θ^+} in KLp \to K+n reaction in KLF at JLab

The possibility of the existence of multiquark hadrons made of 4-quark for mesons and 5-quark for baryons was predicted by Gell-Mann in Ref. [1]. The renewed interest for the search of exotic pentaquark states was initiated by the paper by Diakonov, Petrov, and Polyakov in Ref. [2]. The 2003 experimental reports on the observation of {Θ^+} pentaquark with a uudd{\bar s} quark content created a big excitement and many following experiments have reported its observation [3]. After high-statistics experiments at JLab, which did not confirm previous claims by the CLAS collaboration, the community concluded that the {Θ^+} pentaquark either does not exist at all or has an extremely small cross section, making it currently unobserved. There were different review papers on this subject, either questioning the existence of the {Θ^+} or attempting to explain the reasons why reaching a conclusion based on production experiments is challenging [4]. To address the challenge of minimal 3-body final states, a formation experiment with a projectile kaon beam is proposed. Below, we discuss how the {Θ^+} could be observed in the KLp \to {Θ^+} \to {K^+}n reaction in the KLF experiment at JLab [5].

hep-ex↗
arXiv2023

Quark Confinement for Multi-Quark Systems -- Application to Fully-Charmed Tetraquarks

A new color basis system and confinement mechanism for multi-quark systems are proposed according to the string-type picture of QCD. The color string configurations in the strong coupling QCD are implemented in the set of color basis states. The extended color Hilbert space for $QQ\bar Q\bar Q$ systems includes a ''hidden color'' state, which mixes with two-meson states $Q\bar Q+Q\bar Q$, This mixing effect leads to an attractive potential sufficient to form a bound state. We apply a realistic Hamiltonian model with the new scheme to fully charmed tetraquark states, $cc\bar c\bar c$, and find a bound and two resonant states, which could potentially correspond to the $cc\bar c\bar c$ tetraquark candidates recently observed in experiments.

hep-ph↗
arXiv2023

Spectral function of the $η'$ meson in nuclear medium based on phenomenological models

The in-medium modification of the spectral function of the $η'$ meson with and without the spatial momentum is studied with the $Tρ$ approximation by employing two phenomenological models for the $η'N$ scattering; one is called coupled channels model and the other the $N(1895)$-dominance model. In the former model, the $η'N$ scattering amplitude is calculated in the unitarized coupled-channel approach involving the $η'N$ channel, while in the latter model the $η'N$ scattering process is dominated by the $N(1895)$ resonance with the spin and parity $J^P=1/2^-$. In the \com{coupled channels model}, one single peak of the in-medium $η'$ mode appears in the spectral function and the peak position shifts to higher energies along with the increase of the nuclear density reflecting the repulsive $η'N$ scattering length of the unitarized coupled-channel amplitude. On the other hand, two branches related to the $η'$ and $N(1895)$-hole modes appear in the $N(1895)$-dominance model. In both models, the shift of the peak position and the width in the spectral function are a few tens of MeV at the normal nuclear density for the $η'$ meson at rest in the nuclear medium. Once the spatial momentum is turned on, the peak positions in the spectral function approach the energies without the nuclear medium effect. Particularly, in the $N(1895)$-dominance model, the peak strength of the $N(1895)$-hole mode gets smaller with the finite momentum and the spectral function comes to have one single peak.

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arXiv2022

Inverse mass ordering of light scalar mesons in the Nambu Jona-Lasinio model

The masses of the low-lying scalar mesons are investigated in the three-flavor Nambu Jona-Lasinio (NJL) model by treating the scalar mesons as composite objects of a quark and an antiquark. It is known that a simple $\bar qq$ picture fails to reproduce so-called inverse mass ordering for the scalar mesons. Recently a new mechanism to reproduce the observed mass spectrum of the scalar mesons was proposed in a linear sigma model by introducing flavor symmetry breaking induced by the U(1) axial anomaly. Motivated by this proposal, we examine whether this new mechanism works also in the NJL model. By calculating the scalar meson masses, we find that the NJL model reproduces the observed mass ordering with sufficient strength of the new term. With this mechanism, it turns out that the constituent strange quark mass gets degenerate to that of the up and down quark if the inverse mass ordering is reproduced. We also discuss the scalar diquark masses to check the consistency of the degeneracy of the constituent quark masses with the light baryon masses.

hep-ph↗
arXiv2022

Excitation spectra of heavy baryons in diquark models

The excitation energy spectra of heavy baryons consisting of a heavy quark and two light quarks are investigated by using diquark models in order to examine the nature of the diquark as a constituent of single heavy baryons. We consider two diquark models; in model A the diquark is treated as a point-like particle, while it has a spatial size in model B. We determine the masses of scalar and axial vector diquarks by the mass difference of the ground state charmed baryons to the $Λ_{c}$ baryon, while the mass of the $ud$ scalar diquark in the $Λ_{c}$ baryon is assumed to be 500 MeV as a reference. The parameters of these models are fixed by the $1p$ excitation energy of $Λ_{c}$. We find that model A reproduces well the excitation energy spectra of the charmed and bottomed baryons, although the string tension of the confinement potential in model A should be a half of that of the charmonium, while Model B suggests degeneracy of the $2s$ and $1d$ states, which is not seen in the $Λ_{c}$ spectrum.

hep-ph↗
arXiv2022

Sum rule for the partial decay rates of bottom hadrons based on the dynamical supersymmetry of the $\bar s$ quark and the $ud$ diquark

We investigate the weak decays of $\bar B_{s}^{0}$ and $Λ_{b}$ to charm hadrons based on the dynamical supersymmetry between the $\bar s$ quark and the $ud$ diquark. We derive a new sum rule relating the decay rates of the processes $\bar B_{s}^{0} \to D_{s}^{+} P^{-}$, $\bar B_{s}^{0} \to D_{s}^{*+} P^{-}$ and $Λ_{b} \to Λ_{c} P^{-}$, where $P^{-}$ is a negatively charged meson, such as $π^{-}$ and $K^{-}$. It is found that the observed decay rates satisfy the sum rule very well. This implies that the supersymmetry between the $\bar s$ quark and the $ud$ diquark is also seen in the wavefunctions of the heavy hadrons and suggests that the $ud$ diquark can be regarded as a valid effective constituent for heavy hadrons.

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