Searcharxiv⌕ Search

arXiv subjects

Satoru Hirenzaki

Publications and source records attributed to Satoru Hirenzaki.

At least 19 recordsLinked to original sources
arXiv2026

First Measurement of the $K^-$ Escape Cross Section in the ${}^{12}{\rm C}(K^{-},p)$ Reaction

We investigated the $\bar{K}$-nucleus interaction through the simultaneous measurement of the inclusive $^{12}{\rm C}(K^-, p)$ and exclusive $K^-$-escape $^{12}{\rm C}(K^-, p K^-_{esc})$ reactions at $1.8$ GeV/$c$ at J-PARC. The present measurement explicitly focuses on the $K^-$ escape process for the first time, successfully accomplishing a direct experimental determination of the imaginary part of the $K^-$ optical potential. The differential cross section for the $K^-$-escape reaction was determined to be $436 \pm 6\:(\text{stat.}) \pm 44\:(\text{syst.})~μ\text{b/sr}$. A simultaneous likelihood fit yielded real and imaginary potential strengths of $V_0 = -72\:^{+3}_{-5}\:(\text{stat.})\:^{+0}_{-8}\:(\text{syst.})~\text{MeV}$ and $W_0 = -100\:^{+7}_{-1}\:(\text{stat.})\:^{+0}_{-16}\:(\text{syst.})~\text{MeV}$ at the nuclear center, respectively. The derived $W_0$ is significantly stronger than that predicted by theoretical models based on one-nucleon processes, suggesting possible contribution of multi-nucleon involving processes.

nucl-ex↗
arXiv2026

Feasibility of the observation of $η^{\prime}$ mesic nuclei in the semi-exclusive $^{12}$C($p, dp$) reaction

We study theoretically the feasibility of the semi-exclusive $^{12}$C($p,dp$)$X$ reaction for the observation of $η^\prime$ mesic nuclei using the microscopic transport model JAM. The semi-exclusive measurements of the ($p,d$) reaction with protons from $η^\prime$ absorption are found to be significant for the observation of the $η^\prime$ bound states. Especially, the measurements of the energetic protons from $η^\prime$ non-mesic two-body absorption ($η^\prime NN \to NN$) are considered to be critically important. The Green's function method is used to calculate the expected spectrum of forward going deuterons corresponding to the excitation energy spectrum of the $η^\prime \otimes {}^{11}$C system in the semi-exclusive measurement. The semi-exclusive measurements are shown to be important in general for the $η^\prime$ mesic nucleus observation.

nucl-th↗
arXiv2026

Structure and Formation of the Deeply Bound $\bar{p}$ atoms

We study theoretically the structure and formation of the deeply bound $\bar{p}$ atoms. We find that the widths of the atomic states are narrower than the level spacing even for deeply bound states so that the well-isolated deeply bound $\bar{p}$ atoms are expected to exist. We also find the $\bar{p}$-nuclear states with huge widths. For the observation of the deep $ {\bar p}$-atomic states, we investigate theoretically the $(\bar{p}, p)$ reactions for $^{12}$C, $^{16}$O, and $^{31}$P target nuclei. We find that the momentum transfer of the $( {\bar p},p)$ reaction is small and the formation of the $ {\bar p}$-atomic states can be observed as the discrete peak structures in the $( {\bar p},p)$ spectrum. We conclude that the $(\bar{p}, p)$ reactions are very much suited for the $\bar{p}$ atom formation and the spectra of the reaction are expected to provide new valuable information on the $ {\bar p}$ atoms and $ {\bar p}$-nucleus interaction.

hep-ph↗
arXiv2025

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.

nucl-th↗
arXiv2023

Chiral symmetry restoration at high matter density observed in pionic atoms

Modern theories of physics tell that the vacuum is not an empty space. Hidden in the vacuum is a structure of anti-quarks $\bar{q}$ and quarks $q$. The $\bar{q}$ and $q$ pair has the same quantum number as the vacuum and condensates in it since the strong interaction of the quantum chromodynamics (QCD) is too strong to leave it empty. The $\bar{q}q$ condensation breaks the chiral symmetry of the vacuum. The expectation value $<\bar{q}q>$ is an order parameter. For higher temperature or higher matter-density, $|<\bar{q}q>|$ decreases reflecting the restoration of the symmetry. In contrast to these clear-cut arguments, experimental evidence is so far limited. First of all, the $\bar{q}q$ is nothing but the vacuum itself. It is neither visible nor perceptible. In this article, we unravel this invisible existence by high precision measurement of pionic atoms, $π^-$-meson-nucleus bound systems. Using the $π^-$ as a probe, we demonstrate that $|<\bar{q}q>|$ is reduced in the nucleus at 58% of the normal nuclear density by a factor of 77 $\pm$ 2% compared with that in the vacuum. This reduction indicates that the chiral symmetry is partially restored due to the extremely high density of the nucleus. The present experimental result clearly exhibits the existence of the hidden structure, the chiral condensate, in the vacuum.

nucl-ex↗
arXiv2023

Pion-nucleon sigma term $σ_{πN}$ and deeply bound pionic atoms

We investigate the possibility to determine the value of the pion-nucleon sigma term $σ_{πN}$ precisely by the experimental observables of the deeply bound pionic atoms. We discuss the sensitivity of the observables to $σ_{πN}$ and take into account the typical errors of the up-to-date experiments of the deeply bound pionic atoms. We find that the gap of the binding energies and the width of the deeply bound pionic states are good observables for the $σ_{πN}$ value determination by the experimental data. We also discuss the expected difficulties for the accurate determination of the value of $σ_{πN}$ due to the correlation between the $σ$ term and the potential parameter in the pion-nucleus optical potential.

nucl-th↗
arXiv2021

Structure of double pionic atoms

We study theoretically the structure of double pionic atoms, in which two negatively charged pions ($π^-$) are bound in the atomic orbits. The double pionic atom is considered to be an interesting system from the point of view of the multi bosonic systems. In addition, it could be possible to deduce valuable information on the isospin $I = 2$ $ππ$ interaction and the pion-nucleus strong interaction. In this paper, we take into account the $ππ$ strong and electromagnetic interactions, and evaluate the effects on the binding energies by perturbation theory for the double pionic atoms in heavy nuclei. We investigate several combinations of two pionic states and find that the order of magnitude of the energy shifts due to the $ππ$ interaction is around 10 keV for the strong interaction and around 100 keV for the electromagnetic interaction for the ground states.

nucl-th↗
arXiv2019

Quantum aspects of self-interacting fields around cosmic strings

The authors study the quantum effect of self-interacting fields in the classical background of conical space, i.e. around a cosmic string with infinitesimal width. The renormalized value of $\langleϕ^2\rangle$ and energy-momentum tensor in the presence of cosmic strings are calculated in the self-interacting scalar field theory. The amount of condensation is also estimated in the case of the Dirac Lagrangian with the four-fermion interaction. The physical implications of the above analyses are discussed.

hep-th↗
arXiv2019

Origin of energy shift in kaonic atom and kaon-nucleus interaction

The $K^-$-nucleus optical potential is revisited to investigate its global feature phenomenologically. It is a puzzle that the energy shift is found to be repulsive in all of the observed kaonic atom, although the $K^-N$ interaction is known to be so attractive as to form the $Λ(1405)$ resonance. To solve this puzzle, we examine the $K^-$ optical potential in the linear density approximation and determine the potential parameters of each kaonic atom so as to reproduce the observed energy shift and absorption width. We find two types of the potentials. One potential has a so large real part as to provide nuclear states with the same quantum number to the atomic state in the last orbit. The level repulsion between the atomic state and the nuclear states takes place due to their mixing, and it makes the atomic state shifted repulsively. The other type of the potential has a large imaginary part and the imaginary part works repulsively for atomic states. We find that only the latter solution reproduce a wide of the observed data, and thus is realized as a $K^-$-nucleus potential for kaonic atom. In the linear nuclear density optical potential, the picture that the repulsive shifts in the atomic states stem from the existence of the nuclear states does not globally stand up. This implies that the $K^-$-nucleus optical potential should have a large imaginary part. We examine some nonlinear density effects and find that the conclusion does not change. We also confirm that the conventionally known optical potentials are categorized into the latter type of the potential.

nucl-th↗
arXiv2019

Cosmic strings in compactified gauge theory

A solution of the vortex type is given in a six-dimensional $SU(2)\times U(1)$ pure gauge theory coupled to Einstein gravity in a compactified background geometry. We construct the solution of an effective abelian Higgs model in terms of dimensional reduction. The solution, however, has a peculiarity in its physically relevant quantity, a deficit angle, which is given as a function of the ratio of the gauge couplings of $SU(2)$ and $U(1)$. The size of the extra space (sphere) is shown to vary with the distance from the axis of the "string".

hep-th↗
arXiv2019

Structure of eta' mesonic nuclei in a relativistic mean field theory

The structure and the energy spectrum of the $η^{\prime}$ mesonic nuclei are investigated in a relativistic mean field theory. One expects a substantial attraction for the $η^{\prime}$ meson in finite nuclei due to the partial restoration of chiral symmetry in the nuclear medium. Such a hadronic scale interaction for the $η^{\prime}$ mesonic nuclei may provide modification of the nuclear structure. The relativistic mean field theory is a self-contained model for finite nuclei which provides the saturation property within the model, and is good to investigate the structure change of the nucleus induced by the $η^{\prime}$ meson. Using the local density approximation for the mean fields, we solve the equations of motion for the nucleons and the $η^{\prime}$ meson self-consistently, and obtain the nuclear density distribution and the $η^{\prime}$ energy spectrum for the $η^{\prime}$ mesonic nuclei. We take $^{12}$C, $^{16}$O and $^{40}$Ca for the target nuclei. We find several bound states of the $η^{\prime}$ meson for these nuclei thanks to the attraction for $η^{\prime}$ in nuclei. We also find a sufficient change of the nuclear structure especially for the $1s$ bound state of $η^{\prime}$. This implies that the production of the $1s$ bound state in nuclear reaction may be suppressed.

nucl-th↗
arXiv2018

Bogomol'nyi Equations for Vortices in Born-Infeld-Higgs Systems

We study vortex solutions in the Born-Infeld theory coupled with a complex scalar field. We show that for a specific form of the "Higgs" potential the vortex satisfies a set of Bogomol'nyi-type equations. Another model, with nonlinear interaction between gauge and Higgs fields, is also considered. We show how it is derived from a supersymmetric extension of the Born-Infeld theory with a minimally coupled complex scalar field.

hep-th↗
arXiv2018

Euclidean wormhole solutions of Einstein-Yang-Mills theory in diverse dimensions

We solve the Euclidean Einstein equations with non-Abelian gauge fields of sufficiently large symmetry in various dimensions. In higher-dimensional spaces, we find the solutions which are similar to so-called scalar wormholes. In four-dimensional space-time, we find singular wormhole solutions with infinite Euclidean action. Wormhole solutions in the three-dimensional Einstein-Yang-Mills theory with a Chern-Simons term are also constructed.

gr-qc↗
arXiv2018

Vacuum energy for Yang-Mills fields in $R^d\times S^1$: One-loop, two-loop, and beyond

The vacuum energy is calculated for Yang-Mills (YM) system defined in $D$ dimensional space-time of $S^1\times R^d$ ($D=d+1$), where the possibility of the YM fields to acquire the vacuum expectation values on $S^1$ is taken into account. The vacuum energy has already been obtained to the order of one-loop in many people. Here we calculate the vacuum energy in $D$ dimensions to two-loop order. With an intention to reach higher loops, an approximation method is proposed, which is especially effective in higher dimensions. By this method, we can treat the higher-loop contributions of YM interactions as easily as we treat one-loop effect. As a check, we show reproduction of the two-loop contribution ($D$-dependence of the coefficient as well as the functional form) when the coupling constant is small. This approximation method is useful not only for the Kaluza-Klein theories but also for the finite temperature-density system (as a quark-gluon plasma).

hep-th↗
arXiv2015

Effect of Self-Interaction on Vacuum Energy for Yang-Mills System in Kaluza-Klein Theory

We calculate the vacuum energy for Yang--Mills (YM) system in the background space-time $M^4 \times S^3$, taking the effect of self-interaction of the YM fields into account. The compactification scale obtained by Candelas--Weinberg mechanism becomes large if the YM coupling is large. The case with an extra space $S^3/Z_2$ is also considered, and it is shown that the vacuum associated with broken gauge symmetry is unstable.

hep-th↗
arXiv2013

(d,3He) reaction on odd-neutron nuclear target for the formation of deeply bound pionic atoms

We consider the pionic atom spectroscopy by the (d,3He) reaction on an odd-neutron nuclear target in this article, which has not been investigated so far. In the (d,3He) reaction on the odd-neutron nuclear target, we can observe the pionic states in the even-neutron nucleus with spin-parity 0+. We expect that this pionic state does not have the additional shifts due to the effects of the residual interaction between neutron-hole and pionic states. For the even-neutron nuclear target cases, we may have to take into account the residual interaction effects to deduce the binding energies of the pionic states precisely from the high precision experimental data since the final pionic states are the pion-particle plus neutron-hole states. Thus, in addition to widening the domain of the pionic atom spectroscopy in nuclear chart, the present study of the (d,3He) reaction on the odd-neutron target is considered to be important to deduce extremely precise information on the binding energies of the observed pionic states, and to know the pion properties and aspects of the symmetries of the strong interaction at finite density. We modify the formula of the even-even nuclear target case to study the pionic atom formation spectra on the even-odd nuclear target and show the numerical results of 117Sn target case. This experiment will be performed at RIBF/RIKEN in near future.

nucl-th↗