arXiv subjects

Katsuhiko Suzuki

Publications and source records attributed to Katsuhiko Suzuki.

At least 19 recordsLinked to original sources

arXiv2026

Impact of Effective Nucleon Mass and Multineutron States on the Equation of State for Core-Collapse Supernovae

In this study, we investigate the impact of effective nucleon mass and the existence of the dineutron $(\mathrm{^{2}n})$ and the tetraneutron $(\mathrm{^{4}n})$ on the thermodynamic properties and nuclear compositions by constructing new equations of state. Our results indicate that the model with a larger effective nucleon mass slightly alters the nuclear composition in neutron-rich environments primarily due to differences in the symmetry energy: the mass fractions of unbound neutrons, protons, and heavy nuclei increase. The impact on the thermodynamic properties is negligible, except for the chemical potentials. On the other hand, multineutron states become prominent at high densities in neutron-rich environments, leading to a substantial reduction in the unbound neutron fraction. This depletion lowers the chemical potential of unbound neutrons, which in turn reduces the abundance of neutron-rich nuclei. Consequently, the number of unbound protons increases, leading to a corresponding rise in proton chemical potential. These shifts in chemical potentials promote the formation of heavy nuclei with larger mass and atomic numbers. Ultimately, this compositional shift results in a lower free energy, primarily driven by the emergence of these heavy nuclei.

nucl-th↗

arXiv2025

Impact of dineutrons on nuclear compositions of a core-collapse supernova

We study the nuclear compositions in the central region of a core-collapse supernova, assuming the existence of dineutrons ($^2n$) and tetraneutrons ($^4n$). At 100~ms after core bounce, ${}^2n$ and ${}^4n$ are more abundant than deuterons within radii of approximately 100 and 50~km, respectively. Compared to the model ignoring the existence of ${}^2n$ and ${}^4n$, the mass fraction of neutrons up to a radius of 100~km reduces, while the mass fractions of protons, deuterons, and $\rm{{}^4He}$ increase. Due to the uncertainties in the properties of $^2n$ and $^4n$, we investigate the influence of their binding energies on the nuclear composition. We find the binding energy of $^2n$ has only a modest effect on the overall composition, except for its own mass fraction, while that of $^4n$ has a negligible impact.

nucl-th↗

arXiv2025

Mineral Detection of Neutrinos and Dark Matter 2025 Proceedings

The third ``Mineral Detection of Neutrinos and Dark Matter'' (MD$ν$DM'25) meeting was held May 20-23, 2025 in Yokohama, Japan, hosted by the Yokohama Institute for Earth Sciences, Japan Agency for Marine-Earth Science and Technology (JAMSTEC). These proceedings compile contributions from the workshop and update the progress of mineral detector research. MD$ν$DM'25 was the third such meeting, following the first in October of 2022 held at the IFPU in Trieste, Italy and the second in January of 2024 hosted by the Center for Neutrino Physics at Virginia Tech in Arlington, USA. Mineral detectors record and retain damage induced by nuclear recoils in synthetic or natural mineral samples. The damage features can then be read out by a variety of nano- and micro-scale imaging techniques. Applications of mineral detectors on timescales relevant for laboratory experiments include reactor neutrino monitoring and dark matter detection, with the potential to measure the directions as well as the energies of the induced nuclear recoils. For natural mineral detectors which record nuclear recoils over geological timescales, reading out even small mineral samples could be sensitive to rare interactions induced by astrophysical neutrinos, cosmic rays, dark matter and heavy exotic particles. A series of mineral detectors of different ages could measure the time evolution of these fluxes, offering a unique window into the history of our solar system and the Milky Way. Mineral detector research is highly multidisciplinary, incorporating aspects of high energy physics, condensed matter physics, materials science, geoscience, and AI/ML for data analysis. Although realizing the scientific potential of mineral detectors poses many challenges, the MD$ν$DM community looks forward to the continued development of mineral detector experiments and the possible discoveries that mineral detectors could reveal.

physics.ins-det↗

arXiv2024

Relativistic BEC extracted from a complex FRG flow equation

Based on the functional renormalization group (FRG) under the local potential approximation, we analyze the Bose-Einstein condensation (BEC) in the relativistic complex scalar theory. This framework leads to a complex flow equation of the effective potential, even with the well-known Litim regulator. In order to evaluate the condensate from such a complex effective potential, we impose a condition between chemical potential and mass, analogously to those in the free theory or the mean field theory. We elucidate that for the strongly (weakly) coupled theory, the phase diagrams computed from the FRG are more (less) deviated from that under the mean field approximation. This result implies that quantum fluctuations strongly affect the nonperturbative formation of the BEC.

hep-ph↗

arXiv2024

Mineral Detection of Neutrinos and Dark Matter 2024. Proceedings

The second "Mineral Detection of Neutrinos and Dark Matter" (MDvDM'24) meeting was held January 8-11, 2024 in Arlington, VA, USA, hosted by Virginia Tech's Center for Neutrino Physics. This document collects contributions from this workshop, providing an overview of activities in the field. MDvDM'24 was the second topical workshop dedicated to the emerging field of mineral detection of neutrinos and dark matter, following a meeting hosted by IFPU in Trieste, Italy in October 2022. Mineral detectors have been proposed for a wide variety of applications, including searching for dark matter, measuring various fluxes of astrophysical neutrinos over gigayear timescales, monitoring nuclear reactors, and nuclear disarmament protocols; both as paleo-detectors using natural minerals that could have recorded the traces of nuclear recoils for timescales as long as a billion years and as detectors recording nuclear recoil events on laboratory timescales using natural or artificial minerals. Contributions to this proceedings discuss the vast physics potential, the progress in experimental studies, and the numerous challenges lying ahead on the path towards mineral detection. These include a better understanding of the formation and annealing of recoil defects in crystals; identifying the best classes of minerals and, for paleo-detectors, understanding their geology; modeling and control of the relevant backgrounds; developing, combining, and scaling up imaging and data analysis techniques; and many others. During the last years, MDvDM has grown rapidly and gained attention. Small-scale experimental efforts focused on establishing various microscopic readout techniques are underway at institutions in North America, Europe and Asia. We are looking ahead to an exciting future full of challenges to overcome, surprises to be encountered, and discoveries lying ahead of us.

astro-ph.CO↗

arXiv2023

Mineral Detection of Neutrinos and Dark Matter. A Whitepaper

Minerals are solid state nuclear track detectors - nuclear recoils in a mineral leave latent damage to the crystal structure. Depending on the mineral and its temperature, the damage features are retained in the material from minutes (in low-melting point materials such as salts at a few hundred degrees C) to timescales much larger than the 4.5 Gyr-age of the Solar System (in refractory materials at room temperature). The damage features from the $O(50)$ MeV fission fragments left by spontaneous fission of $^{238}$U and other heavy unstable isotopes have long been used for fission track dating of geological samples. Laboratory studies have demonstrated the readout of defects caused by nuclear recoils with energies as small as $O(1)$ keV. This whitepaper discusses a wide range of possible applications of minerals as detectors for $E_R \gtrsim O(1)$ keV nuclear recoils: Using natural minerals, one could use the damage features accumulated over $O(10)$ Myr$-O(1)$ Gyr to measure astrophysical neutrino fluxes (from the Sun, supernovae, or cosmic rays interacting with the atmosphere) as well as search for Dark Matter. Using signals accumulated over months to few-years timescales in laboratory-manufactured minerals, one could measure reactor neutrinos or use them as Dark Matter detectors, potentially with directional sensitivity. Research groups in Europe, Asia, and America have started developing microscopy techniques to read out the $O(1) - O(100)$ nm damage features in crystals left by $O(0.1) - O(100)$ keV nuclear recoils. We report on the status and plans of these programs. The research program towards the realization of such detectors is highly interdisciplinary, combining geoscience, material science, applied and fundamental physics with techniques from quantum information and Artificial Intelligence.

astro-ph.IM↗

arXiv2021

Chirality imbalance and chiral magnetic effect under a parallel electromagnetic field

We study the time evolution of the chirality imbalance $n_5$ and the chiral magnetic effect (CME) under the external parallel electromagnetic fields without assuming the artificial chiral asymmetric source. We adopt the time-dependent Sauter-type electric and constant magnetic field, and obtain analytical solutions of the Dirac equation for a massive fermion. We use the point-split regularization to calculate the vacuum contribution in the gauge invariant way. As a result, we find that $n_5$ and CME current increase substantially as the electric field increases, and stay finite after the electric field is switched off. The chirality imbalance and CME current are shown to consist of a dominant contribution, which is essentially proportional to relativistic velocity, and a small oscillating part. We find a simple analytical relation between $n_5$ and the fermion pair-production rate from the vacuum. We also discuss dynamical origin of the chirality imbalance in detail.

hep-ph↗

arXiv2016

Meson cloud effects on the pion quark distribution function in the chiral constituent quark model

We investigate the valence quark distribution function of the pion $v^π(x,Q^2)$ in the framework of the chiral constituent quark model and evaluate the meson cloud effects on $v^π(x,Q^2)$. We explicitly demonstrate how the meson cloud effects affect $v^π(x,Q^2)$ in detail. We find that the meson cloud correction causes an overall 32\% reduction of the valence quark distribution and an enhancement at the small Bjorken $x$ regime. Besides, we also find that the dressing effect of the meson cloud will make the valence quark distribution to be softer in the large $x$ region.

hep-ph↗

arXiv2015

Nucleon structure functions at small $x$ via holographic Pomeron exchange

The analysis on nucleon structure functions at small Bjorken $x$ in the framework of holographic QCD is presented. In the model setup, the complicated nonperturbative interaction between the virtual photon and the target nucleon is described via the Pomeron exchange, which corresponds to the reggeized graviton exchange in the AdS space. We show that our calculations for both $F_2$ and $F_L$ structure functions are in agreement with the experimental data measured at HERA.

hep-ph↗

arXiv2014

Nucleon structure functions at small $x$ via the Pomeron exchange in AdS space with a soft infrared wall

We present analyses on nucleon structure functions at the small Bjorken-$x$ in the framework of holographic QCD. In this study, we improve the description of the target nucleon in the current setup of the holographic model by introducing a soft-wall AdS/QCD model, in which the AdS geometry is smoothly cut off at IR. Combining the improved Pomeron-nucleon coupling and the wave function of the 5D U(1) vector field with the BPST Pomeron exchange kernel, then we obtain the structure functions. Here we focus on the nonperturbative kinematical region, where $10^{-6} \leq x \leq 10^{-2}$ and $0.1 \leq Q^2 \leq 10$ [GeV$^2$], and show that our calculations for $F_2^p$ and $F_L^p$ are consistent with experimental data of the deep inelastic scattering at HERA. Furthermore, we find that the resulting longitudinal-to-transverse ratio of the structure functions, $F_L^p/F_T^p$, depends on both of $x$ and $Q^2$.

hep-ph↗

arXiv2012

Pomeron dynamics in the AdS space and structure functions of hadrons at small x

The Pomeron dynamics is investigated via deep inelastic scattering (DIS) at small x in the framework of holographic quantum chromodynamics. The small x DIS process is assumed to be described by the graviton exchange between external vector current and hadron in the AdS space. Our calculations for $F_2^p$, $F_2^π$, as well as the longitudinal counterpart $F_L^p$ are consistent with the experimental data. We discuss origins of a difference between $F_2$ and $F_L$ in our approach.

hep-ph↗

arXiv2012

Chiral multicritical points driven by isospin density in the Ginzburg-Landau approach

We study how a chiral tricritical point (TCP) on QCD phase diagram is affected by the imbalance of up and down quark densities (isospin density), using the generalized Ginzburg-Landau (GL) approach. The resulting phase diagram near TCP shows a rich fine structure which includes inhomogeneities of both the chiral and the charged pion condensations. It turns out that the TCP splits into multicritical points.

hep-ph↗

arXiv2012

Ginzburg-Landau approach to inhomogeneous chiral phases of QCD

We study the inhomogeneous chiral condensates in the proximity of the chiral tricritical point (TCP) of two-flavor QCD. Deriving the Ginzburg-Landau (GL) functional up to the eighth order in the order parameter and its spatial derivative, we explore off the TCP and find that critical curves are bent by non-linear effects. In the newly extend GL coupling space, we find the TCP being realized as a multicritical point where five independent critical lines meet up. We also present general analyses for the energies associated with several higher dimensional crystal structures.

hep-ph↗

arXiv2012

Splitting of the chiral critical point and realization of solitonic pion condensate driven by isospin density

We study the influence of the isospin asymmetry on the phase structure of strongly interacting quark matter near the tricritical point (TCP) using a generalized Ginzburg-Landau approach. The effect has proven to be so drastic, not only bringing about the shift of the location of TCP, but resulting in a rich fine structure at the vicinity of TCP. In particular, we find that an arbitrary small perturbation due to isospin density lifts the degeneracy of TCP making it split into four independent multicritical points. Accordingly, the homogeneous pion condensate and its solitonic counterpart come to occupy large domains in the Ginzburg-Landau coupling space.

hep-ph↗

arXiv2012

Transition from soft- to hard-Pomeron in the structure functions of hadrons at small-$x$ from holography

We study the nucleon and pion structure functions at small Bjorken-$x$ region in the framework of holographic QCD with a special emphasis on the roles of AdS space wave functions. Using the BPST kernel for the Pomeron exchange and calculating its coupling to target hadrons in the AdS space, we obtain $F_2$ structure functions at the small-$x$. Results for the proton $F^p_2$ as well as the pion $F^π_2$ are consistent with experimental data of the deep inelastic scattering and the forward electroproduction of a neutron. Observed $Q^2$ dependence of the Pomeron intercept is well reproduced from soft non-perturbatibve $(Q^2 \sim 0)$ to hard perturbative $(Q^2 \gg 1 GeV^2)$ region. We find the interplay between soft and hard Pomerons is closely related with behavior of AdS wave functions of hadrons and the virtual photon.

hep-ph↗

arXiv2012

Crystalline chiral condensates off the tricritical point in a generalized Ginzburg-Landau approach

We present an extensive study on inhomogeneous chiral condensates in QCD at finite density in the chiral limit using a generalized Ginzburg-Landau (GL) approach. Performing analyses on higher harmonics of one-dimensionally (1D) modulated condensates, we numerically confirm the previous claim that the solitonic chiral condensate characterized by Jacobi's elliptic function is the most favorable structure in 1D modulations. We then investigate the possibility of realization of several multidimensional modulations within the same framework. We also study the phase structure far away from the tricritical point by extending the GL functional expanded up to the eighth order in the order parameter and its spatial derivative. On the same basis, we explore a new regime in the extended GL parameter space and find that the Lifshitz point is the point where five critical lines meet at once. In particular, the existence of an intriguing triple point is demonstrated, and its trajectory consists of one of those critical lines.

hep-ph↗

arXiv2003

Investigation of the color-dipole structure in diffractive t-slopes of charmonia photo- and electroproductions

The diffractive t-slope, B_V, of elastic charmonia (V=J/psi, psi') photo- and leptoproductions off a nucleon is studied at low |t| (< 1 GeV^2) in the leading logarithmic approximation of perturbative QCD, with a special emphasis on the space-time evolution of the c\bar{c}-dipole. We obey a framework based on QCD factorization, which describes a certain Fermi motion effect due to the $c(\bar{c})$-quarks in the proper manner and includes appropriately kinematical corrections of the momentum transfer Delta_perp in the t-channel. Assuming the universal two-gluon form factor of the nucleon, we show that the difference of t-slopes for J/psi and psi' is dominated by the contribution from the dipole-charmonium transition process. The calculated difference is found to be B_J/psi-B_psi' \sim 0.53 GeV^-2 for the photoproduction, in agreement with HERA data. We also calculate the t-dependence of the total cross sections for several center-of-mass energies W. A good agreement of the results with the available data demands that the mass scale appearing in the gluon form factor should significantly decrease with increasing W.

hep-ph↗

arXiv2000

Constraints on color dipole-nucleon cross section from diffractive heavy quarkonium production

We study the hard color dipole-nucleon cross section within perturbative QCD and discuss its relation to observables in diffractive leptoproduction of heavy quarkonium. The dipole cross section calculated with the unintegrated gluon density of the nucleon substantially differs from the well-known perturbative form $σ_{dip} \sim b^2$ for $b > 0.3$fm, where $b$ is the transverse separation of the dipole. We show the measured ratio of $ψ'$ to $J / ψ$ photoproduction cross sections constrains the dipole cross section at intermediate $b$, and in fact excludes the simple $σ_{dip} \sim b^2$ behavior. We also calculate the $t$-slopes of the diffractive $J / ψ, ψ'$ productions. We emphasize the difference of $t$-slopes, $B_{J/ψ} - B_{ψ'}$, is dominated by the dipole-nucleon dynamics. This difference is found to be about $0.3 {GeV}^{-2}$ with our dipole cross section.

hep-ph↗