arXiv subjects

H. Kamada

Publications and source records attributed to H. Kamada.

At least 19 recordsLinked to original sources

arXiv2026

$\Xi$-deuteron low-energy $s$-wave phase shifts and momentum correlation functions in Faddeev formulation

The low-energy $\Xi$-deuteron scattering is investigated through the solution of Faddeev equations, employing three sets of the currently available representation of the $\Xi$-nucleon interactions. One of these is the chiral NLO interaction specified by the J\"{u}lich group, and the other two are based on the calculations by the HAL-QCD method. The $s$-wave phase shifts in the $J=3/2$ and $J=1/2$ states are presented. Three-body wave functions in coordinate space are constructed from the Faddeev amplitudes in momentum space. These functions are used in the calculation of $\Xi d$ momentum correlation functions. The effects of the deuteron breakup are significant in the $J=3/2$ channel. The differences in the magnitude of the calculated correlation function show the quantitative difference of the $\Xi N$ interactions in the spin-isospin channels. The prospective experimental data on the $\Xi d$ momentum correlation function could contribute to a better description of the $\Xi N$ interactions.

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arXiv2026

Field-theoretical description of the deuteron breakup in the clothed particle representation

We present a field-theoretical description of the deuteron electrodisintegration reaction d(e,e'p)n induced by unpolarized and polarized electrons. The approach combines the Lehmann-Symanzik-Zimmermann in(out) formalism with the clothed particle representation in the instant form of relativistic dynamics, providing a fully relativistic and gauge-independent framework based on the Fock-Weyl criterion. Within the method of unitary clothing transformations, one and the same transformation that generates the relativistic nucleon-nucleon interaction (the Kharkiv potential) also induces a fresh family of electromagnetic current operators. As a result, one-body and two-body (meson-exchange) currents emerge on a common footing. We compute differential cross sections and polarization observables with the inclusion of final-state interaction effects and meson-exchange current contributions, and compare the results with Saclay and Jefferson Lab data as well as with earlier theoretical predictions. The role of relativistic ingredients (one- and two-body currents, Fermi-motion effects, etc.) and the interplay between them are analyzed in several kinematic regimes of the experiments at Saclay and Jefferson Lab.

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arXiv2026

Comparison of Relativistic and Non-relativistic Faddeev calculations for Proton-Deuteron Elastic Scattering

This investigation compares non-relativistic and relativistic nucleon-nucleon potentials in the context of proton-deuteron scattering. Conventional NN potentials (e.g., CDBonn, AV18, Nijmegen) rely on the nonrelativistic Schroedinger equation, whereas the Kharkiv potential is intrinsically relativistic. We employ the Coester-Pieper-Serduke (CPS) and Kamada-Gloeckle (KG) conversion methods to construct a phenomenological-relativistic potential (PRP) from a realistic NN potential, preserving the deuteron binding energy and phase shifts. Focusing on relativistic effects and not including Coulomb forces to avoid complexity, the solutions are compared by solving relativistic and nonrelativistic Faddeev equations. Calculations of the differential cross section using the relativistic Faddeev equation show that relativistic effects - particularly the deviation at the backward angle - become pronounced at 135 MeV. The differences in the forward angle were attributed to the characteristics of the Kharkiv potential itself. The reverse transformation of the Kharkiv potential into a pseudo-nonrelativistic potential (PNRP) confirms that the backward-angle relativistic effect increases with energy in the range from 100 MeV to 400 MeV. Comparisons of the polarization observables indicate that relativistic effects, as well as the discrepancy between the CPS and KG transformations, become significant above 300 MeV. However, for polarization observations below 300 MeV, the nonrelativistic results from PNRP do not deviate significantly from relativistic calculations.

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arXiv2025

$\Lambda$-deuteron momentum correlation functions incorporating deuteron breakup contributions in Faddeev formulation

The effects of the deuteron breakup are estimated for the $\Lambda$-deuteron momentum correlation function. Faddeev amplitudes in calculating low-energy $\Lambda$-deuteron scattering can provide not only the elastic scattering part but also breakup wave functions in the incident and the rearrangement channels. Calculations are carried out using nucleon-nucleon (NN) and hyperon-nucleon (YN) interactions parametrized in chiral effective field theory. The effects of the breakup in the incident channel are found to be marginally insignificant. Those of the rearrangement channel are not negligible, but not large when the source radius is larger than 2.5 fm. Nevertheless, it is worthwhile to have the information on the magnitude of these effects in analyzing the experimental data.

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arXiv2025

Observability of modified threshold behavior near unitarity

A number of recent references have pointed out that an N-particle system having short-range interactions at S-wave and/or P-wave unitarity can exhibit modified threshold behavior for various reactive processes. But the question of how close to unitarity one must get in order to observe such modifications has not been addressed. The present study quantities this question by treating cases involving 3- or 4-neutrons, at the physical value of the neutron-neutron singlet scattering length a and at artificially altered values. One major conclusion is that the neutron-neutron scattering length is not yet sufficiently large for the 3n or 4n systems to demonstrate the unitarity threshold exponent.

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arXiv2024

Faddeev calculations of low-energy $\Lambda$-deuteron scattering and momentum correlation function

Faddeev calculations of low-energy $\Lambda$-deuteron elastic scattering are performed up to $E_{cm}=20$ MeV across the deuteron threshold. Phase shifts of the $s$-wave with $J=1/2$ and $J=3/2$ are calculated using strangeness $S=-1$ hyperon-nucleon interactions in chiral effective field theory NLO13 and NLO19 parametrized by the J{\"u}lich-Bonn group. Effective range parameters, such as a scattering length and an effective range, are determined through the calculated phase shifts. $\Lambda$-deuteron momentum correlation functions are evaluated using the $\Lambda$-deuteron relative wave function constructed from half-off-shell $t$-matrices. They are compared with those evaluated using an approximate formula.

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arXiv2023

Contributions of $2\pi$-exchange, $1\pi$-exchange, and contact three-body forces in NNLO ChEFT to $_\Lambda^3$H

Faddeev calculations of hypertriton ($_\Lambda^3$H) separation energy are performed, incorporating all next-to-next-to-leading-order $\Lambda$NN three-body forces (3BFs) in chiral effective field theory: $2\pi$-exchange, $1\pi$-exchange, and contact interactions. The $1\pi$-exchange and contact interactions are rewritten in a form suitable for evaluating partial-wave matrix elements. The $\Lambda$-deuteron folding potentials constructed from these 3BFs are evaluated to demonstrate their contributions to \h3t. The $1\pi$-exchange interaction provides an attractive effect in which the d-state component of the deuteron wave function plays an important role. The attractive contribution tends to cancel the repulsive ones from the $2\pi$-exchange and contact 3BFs. Faddeev calculations show that the net effect of the 3BFs to the \h3t separation energy is small in a range between $-5$ to $+20$ keV, depending on the NN interaction used. Although these results are based on speculative low-energy constants, they can serve as a reference for further investigations.

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arXiv2023

Faddeev Calculation of $_\Lambda^3$H incorporating 2{\pi}-exchange $\Lambda$NN Interaction

Faddeev calculations of hypertriton ($_\Lambda^3$H) separation energy are performed, incorporating $2\pi$-exchange $\Lambda $NN three-baryon force. Repulsive contributions of the three-baryon force in the order of 20 keV are found, depending on the NN interactions employed. The effect is not negligible compared with the small separation-energy of $_\Lambda^3$H.

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arXiv2022

Partial-wave expansion of $ΛNN$ three-baryon interactions in chiral effective field theory

An expression of partial wave expansion of three-baryon interactions in chiral effective field theory is presented. The derivation follows the method by Hebeler et al. [Phys. Rev. C{\bf 91}, 044001 (2015)], but the final expression is more general. That is, a systematic treatment of the higher-rank spin-momentum structure of the interaction becomes possible. Using the derived formula, a $Λ$-deuteron folding potential is evaluated. This information is valuable for inferring the possible contribution of the $ΛNN$ three-baryon forces to the hypertriton as the basis of further studies by sophisticated Faddeev calculations. A microscopic understanding of $ΛNN$ three-baryon forces together with two-body $ΛN$ interactions is essential for the description of hypernuclei and neutron-star matter.

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arXiv2022

Electron and neutrino scattering off the deuteron in a relativistic framework

We build a relativistic model to perform calculations of exclusive, semi-exclusive and inclusive unpolarized cross sections and various polarization observables in electron and neutrino scattering experiments with deuteron targets. The strong interaction dynamics is defined by an explicit dynamical unitary representation of the Poincar\'e group, where representations of space translations and rotations in the interacting and non-interacting representations are the same. The Argonne V18 potential is used to construct a relativistic nucleon-nucleon interaction reproducing the experimental deuteron binding energy and nucleon-nucleon scattering observables. Our formalism does not include the pion production channel and neglects two-body contributions in the electromagnetic as well as in the weak nuclear current operator. We show that it is applicable to processes at kinematics, where the internal two-nucleon energy remains below the pion production threshold but the magnitude of the three-momentum transfer extends at least to several GeV.

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arXiv2022

Pion absorption from the lowest atomic orbital in 2H, 3H and 3He

The pi- + 2H -> n + n, pi- + 3H -> n + n + n, pi- + 3He -> n + d and pi- + 3He -> p + n + n capture reactions from the lowest atomic orbitals are studied under full inclusion of final state interactions. Our results are obtained with the single-nucleon and two-nucleon transition operators derived at leading order in chiral effective field theory. The initial and final three-nucleon states are calculated with the chiral nucleon-nucleon SMS potential up to N4LO+ augmented by the consistently regularized chiral N2LO three-nucleon potential. We found that absorption rates depend strongly on the nuclear pion absorption operator used, and its two-body parts change the rates by a few orders of magnitude. The final state interactions between nucleons generated by the two-nucleon forces are also important, while the three-nucleon interaction plays a visible role only in the pi- + 3He -> n + d reaction. Our absorption rate for the pi- + 2H -> n + n process is in good agreement with the experimental data from the hadronic ground-state broadening in pionic deuterium. The capture rates on 3He are also generally consistent with the spectroscopic data within error bars, though our central values are found to be systematically below the data. We show that for the three-body breakup processes the dominant contributions to the absorption rates arise from the quasi-free scattering and final-state interaction kinematical configurations.

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arXiv2022

Nuclear properties with semilocal momentum-space regularized chiral interactions beyond N2LO

We present a comprehensive investigation of few-nucleon systems as well as light and medium-mass nuclei up to $A=48$ using the current Low Energy Nuclear Physics International Collaboration two-nucleon interactions in combination with the third-order (N$^2$LO) three-nucleon forces. To address the systematic overbinding of nuclei starting from $A \sim 10$ found in our earlier study utilizing the N$^2$LO two- and three-nucleon forces, we take into account higher-order corrections to the two-nucleon potentials up through fifth order in chiral effective field theory. The resulting Hamiltonian can be completely determined using the $A=3$ binding energies and selected nucleon-deuteron cross sections as input. It is then shown to predict other nucleon-deuteron scattering observables and spectra of light $p$-shell nuclei, for which a detailed correlated truncation error analysis is performed, in agreement with experimental data. Moreover, the predicted ground state energies of nuclei in the oxygen isotopic chain from $^{14}$O to $^{26}$O as well as $^{40}$Ca and $^{48}$Ca show a remarkably good agreement with experimental values, given that the Hamiltonian is fixed completely from the $A \leq 3$ data, once the fourth-order (N$^3$LO) corrections to the two-nucleon interactions are taken into account. On the other hand, the charge radii are found to be underpredicted by $\sim 10\%$ for the oxygen isotopes and by almost $20\%$ for $^{40}$Ca and $^{48}$Ca.

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arXiv2020

Light nuclei with semilocal momentum-space regularized chiral interactions up to third order

We present a systematic investigation of few-nucleon systems and light nuclei using the current LENPIC interactions comprising semilocal momentum-space regularized two- and three-nucleon forces up to third chiral order (N$^2$LO). Following our earlier study utilizing the coordinate-space regularized interactions, the two low-energy constants entering the three-body force are determined from the triton binding energy and the differential cross section minimum in elastic nucleon-deuteron scattering. Predictions are made for selected observables in elastic nucleon-deuteron scattering and in the deuteron breakup reactions, for properties of the $A=3$ and $A=4$ nuclei, and for spectra of $p$-shell nuclei up to $A = 16$. A comprehensive error analysis is performed including an estimation of correlated truncation uncertainties for nuclear spectra. The obtained predictions are generally found to agree with experimental data within errors. Similar to the coordinate-space regularized chiral interactions at the same order, a systematic overbinding of heavier nuclei is observed, which sets in for $A \sim 10$ and increases with $A$.

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arXiv2020

Probing few-body nuclear dynamics via 3H and 3He (e,e'p)pn cross-section measurements

We report the first measurement of the \eep three-body breakup reaction cross sections in helium-3 ($^3$He) and tritium ($^3$H) at large momentum transfer ($\langle Q^2 \rangle \approx 1.9$ (GeV/c)$^2$) and $x_B>1$ kinematics, where the cross section should be sensitive to quasielastic (QE) scattering from single nucleons. The data cover missing momenta $40 \le p_{miss} \le 500$ MeV/c that, in the QE limit with no rescattering, equals the initial momentum of the probed nucleon. The measured cross sections are compared with state-of-the-art ab-initio calculations. Overall good agreement, within $\pm20\%$, is observed between data and calculations for the full $p_{miss}$ range for $^3$H and for $100 \le p_{miss} \le 350$ MeV/c for $^3$He. Including the effects of rescattering of the outgoing nucleon improves agreement with the data at $p_{miss} > 250$ MeV/c and suggests contributions from charge-exchange (SCX) rescattering. The isoscalar sum of $^3$He plus $^3$H, which is largely insensitive to SCX, is described by calculations to within the accuracy of the data over the entire $p_{miss}$ range. This validates current models of the ground state of the three-nucleon system up to very high initial nucleon momenta of $500$ MeV/c.

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arXiv2019

From response functions to cross sections in neutrino scattering off the deuteron and trinucleons

Response functions, differential cross sections and total cross sections for several (anti)neutrino induced reactions on 2H, 3He and 3H are calculated in momentum space for (anti)neutrino energies up to 160 MeV, using the AV18 nucleon-nucleon potential and a single-nucleon weak current operator. This work is a continuation of our investigations presented in J. Golak et al. [Phys. Rev. C 98, 015501 (2018)].

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arXiv2019

Towards high-order calculations of three-nucleon scattering in chiral effective field theory

We discuss the current status of chiral effective field theory in the three-nucleon sector and present selected results for nucleon-deuteron scattering observables based on semilocal momentum-space-regularized chiral two-nucleon potentials together with consistently regularized three-nucleon forces up to third chiral order. Using a Bayesian model for estimating truncation errors, the obtained results are found to provide a good description of the experimental data. We confirm our earlier findings that a high-precision description of nucleon-deuteron scattering data below pion production threshold will require the theory to be pushed to fifth chiral order. This conclusion is substantiated by an exploratory study of selected short-range contributions to the three-nucleon force at that order, which, as expected, are found to have significant effects on polarization observables at intermediate and high energies. We also outline the challenges that will need to be addressed in order to push the chiral expansion of three-nucleon scattering observables to higher orders.

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arXiv2018

Dominance of tensor correlations in high-momentum nucleon pairs studied by (p,pd) reaction

The isospin character of p-n pairs at large relative momentum has been observed for the first time in the 16O ground state. A strong population of the J,T=1,0 state and a very weak population of the J,T=0,1 state were observed in neutron pick up domain of 16O(p,pd) at 392 MeV. This strong isospin dependence at large momentum transfer is not reproduced by the distorted-wave impulse approximation calculations with known spectroscopic amplitudes. The results indicate the presence of high-momentum protons and neutrons induced by the tensor interactions in ground state of 16O.

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arXiv2018

Radiative pion capture in 2H, 3He and 3H

The $π^- + {^2{\rm H}} \rightarrow γ+ n + n$, $π^- + {^3{\rm He}} \rightarrow γ+ {^3{\rm H}}$, $π^- + {^3{\rm He}} \rightarrow γ+ n + d$, $π^- + {^3{\rm He}} \rightarrow γ+ n + n + p$ and $π^- + {^3{\rm H}} \rightarrow γ+ n + n + n$ capture reactions are studied with the AV18 two-nucleon potential and the Urbana~IX three-nucleon potential. We provide for the first time realistic predictions for the differential and total capture rates for all these processes, treating consistently the initial and final nuclear states. Our results are based on the single nucleon Kroll-Ruderman-type transition operator and concentrate on the full treatment of the nuclear final state interactions. They are compared with older theoretical predictions and experimental data.

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