arXiv subjects

Muneto Nitta

Publications and source records attributed to Muneto Nitta.

At least 19 recordsLinked to original sources

arXiv2026

Fermi gas of domain-wall Skyrmions in QCD in a strong magnetic field

Fermionic domain-wall Skyrmions arise in the chiral soliton lattice of two flavor chiral perturbation theory in a magnetic field as the ground state and are associated with baryons of the underlying theory of quantum chromodynamics. We analyze the electromagnetic screening characteristics of domain-wall Skyrmions that give insight into baryon density on the magnetic field and chemical potential phase diagram. At zero temperature, using the moduli effective theory, it is found Skyrmion density is saturated up to the Fermi momenta on the disk of the chiral soliton lattice orthogonal to the magnetic field. We further study chiral perturbation theory coupled to quantum electrodynamics leading to finite temperature screening, wherein a static fermionic domain-wall Skyrmion screening is predicted through a combined Debye mass/length.

hep-ph↗

arXiv2026

Chiral Soliton Lattices under Magnetic Fields and Rotation: a Holographic Analysis

We study the chiral soliton lattice (CSL) in rotating QCD matter under a background magnetic field within holographic QCD. We show that rotation can be incorporated as a background gauge field and that the CSL in rotating matter becomes a ground state in the gravity dual. We also provide a brane interpretation of the CSL under a magnetic field and rotation. Solving the bulk equations, we derive an effective Hamiltonian where the meson decay constant $\tilde{f}$ emerges as an anisotropic, field-dependent matrix. Furthermore, we discuss the thermodynamic properties of the ground state in rotating matter and study its equation of state.

hep-th↗

arXiv2026

Non-Abelian $A_4$ vortices in $SO(3)$ gauge theory and non-invertible symmetries

We construct finite-tension non-Abelian vortex solutions in a renormalizable $(3+1)$-dimensional $SO(3)$ gauge theory Higgsed to the tetrahedral group $A_4$ by a Higgs field in the spin-3 representation. Since the vacuum manifold is $SO(3)/A_4$, the vortices are characterized by the non-Abelian fundamental group $\pi_1(SO(3)/A_4)\simeq \widetilde{A}_4$, the binary tetrahedral group. We obtain explicit axisymmetric vortex solutions carrying holonomies corresponding to the order-two and order-three conjugacy classes of $A_4$, determine their tensions numerically, and show that they exhibit type-I, type-II, and Bogomol'nyi--Prasad--Sommerfield-like behavior depending on the Higgs and gauge boson mass ratios. The vortices are classified by conjugacy classes of $\widetilde{A}_4$, while their infrared descriptions are labeled by conjugacy classes of $A_4$. We further demonstrate that the smooth finite-tension vortices reduce in the infrared to Gukov--Witten surface operators of the $A_4$ discrete gauge theory, thereby establishing a finite-energy ultraviolet completion of non-invertible defects in a renormalizable gauge-Higgs theory.

hep-th↗

arXiv2026

Revisiting the Wess-Zumino-Witten Term in Nuclear and Quark Matter under Magnetic Fields and Rotation

We study anomalous Wess-Zumino-Witten terms associated with the chiral anomaly in dense QCD matter under magnetic fields and rotation. By introducing electromagnetic, baryon number, and isospin background gauge fields, we write down the topological couplings of neutral mesons for the $N_f=2$ and $N_f=3$ cases. The resulting terms contain characteristic contributions proportional to $\vec{B} \cdot \vec{\nabla} \phi$ and $\vec{\Omega} \cdot \vec{\nabla} \phi$, where $\phi$ denotes $\pi^0$, $\eta$, or $\eta'$. These results are relevant to chiral soliton lattices in dense rotating matter.

hep-th↗

arXiv2026

Formation of bound composite vortices of a singly-quantized $^1$S$_0$ vortex and half-quantized $^3$P$_2$ vortices in the $^1$S$_0$-$^3$P$_2$ coexisting phase in neutron stars

Pulsar glitches are believed to originate from the dynamics of quantized vortices in the neutron superfluid interior. The outer core of a neutron star hosts a $^3\text{P}_2$ spin-triplet superfluid, whose half-integer quantum vortices (HQVs) are qualitatively different from the $^1\text{S}_0$ singly quantized vortices (SQVs) in the inner crust. It has recently been proposed that the coupling between these two vortex species gives rise to a large-scale vortex network, providing a candidate mechanism for the diversity of observed pulsar glitch phenomena. Using the Gross--Pitaevskii equations for the $^1\text{S}_0$ and $^3\text{P}_2$ condensates, we perform two-dimensional simulations of one SQV and two HQVs in a coexistence phase near the crust-core boundary, varying the density--density and Josephson coupling constants. We find that the Josephson term, arising from the relative phase between the two condensates, induces a strong attractive interaction between the two HQVs and the SQV, which dominates over the density--density coupling. When pinning potentials are applied to the HQVs and the SQV at spatially separated locations, this attraction is found to be sufficiently strong to drive vortex depinning. These results suggest that two HQVs and one SQV can form a tightly bound composite vortex at the crust-core boundary, with implications for the glitch mechanism in neutron stars.

nucl-th↗

arXiv2026

Fermionic domain-wall Skyrmions of QCD in a magnetic field

The ground state of low-energy QCD matter in strong magnetic fields is either a chiral soliton lattice (CSL), a periodic array of neutral pion domain walls (chiral solitons) perpendicular to the magnetic field, or domain-wall Skyrmion phase, in which Skyrmions are induced on top of the CSL. Previously found domain-wall Skyrmions are bosons with the baryon number two. In this paper, we show that the minimum domain-wall Skyrmions are fermions with baryon number one; a bosonic domain-wall Skyrmion can be separated without energy cost into two fermionic domain-wall Skyrmions attached on the opposite sides of a chiral soliton. The phase boundary between the CSL and domain-wall Skyrmion phases is unchanged. In the chiral limit, the CSL reduces to a linearly dependent neutral pion on the direction of the magnetic field, while fermionic domain-wall Skyrmions sit in an equal distance of half a period.

hep-ph↗

arXiv2026

Baryonic vortices in rotating nuclear matter

We investigate baryonic vortices as topological excitations in rotating nuclear matter within the framework of chiral perturbation theory. We identify two distinct configurations: local and global vortices, both carrying the baryon number as the topological charge associated with the third homotopy group $\pi_3(S^3)$. For the local vortex, similar to the vortex Skyrmion in a finite isospin chemical potential, charged pions form the condensate on the boundary and have a phase winding, while the neutral pion varies along the rotation axis inside the vortex core. On the other hand, a global vortex is formed by the condensate and phase winding of the neutral pion, while the charged pions vary on the inside along the rotation axis. Crucially, although global vortices are usually discarded in infinite systems due to logarithmic divergence in energy, we demonstrate that the finite-size constraint dictated by causality in a rotating frame regularizes the divergence physically, rendering the global vortex a viable excitation. We reveal an energetic competition between global and local vortex states, under the tunable parameters of rotation, system size, and baryon chemical potential. Our results suggest that the previously overlooked global vortex can play a significant role in the topological structure of rotating dense QCD matter.

hep-ph↗

arXiv2026

Holographic QCD Matter: Chiral Soliton Lattices in Strong Magnetic Field

We investigate the chiral soliton lattice (CSL) in the framework of holographic QCD in magnetic field. Under appropriate boundary conditions for the gauge field and the quark mass deformation, we demonstrate that the ground state in the gravitational dual of QCD is given by the CSL in the background magnetic field and the baryon number density. In the presence of the background magnetic field, we show that the CSL is interpreted as a uniformly distributed D4-branes in the holographic setup, where the chiral soliton is identified with a non-self-dual instanton vortex or a center vortex in the five dimensional bulk gauge theory. While the baryon numbers are given to chiral solitons as well as Skyrmions due to the different terms in the Wess-Zumino-Witten (WZW) term in the chiral perturbation theory, these baryon numbers with different origins are unified in terms of the instanton charge density in five dimensions. With bulk analysis of the WZW term, we find that the pion decay constant becomes dependent on the magnetic field. For the massless pion case, we obtain an analytical form that is in qualitative agreement with lattice QCD results for strong magnetic fields.

hep-th↗

arXiv2026

QCD phase diagram in a magnetic field with baryon and isospin chemical potentials

Based on the chiral perturbation theory at the leading order, we present the phase diagram of low-energy QCD in a magnetic field at finite baryon and isospin chemical potentials. The phase diagram consists of the QCD vacuum, the chiral soliton lattice, the uniform charged pion condensation, an Abrikosov vortex lattice of the charged pions, a baryonic vortex lattice composed of neutral and charged pion vortices with their topological linking number being the baryon number, and a hybrid phase of chiral soliton and vortex lattices, with their intersections carrying the baryon number. While the chiral soliton lattice demands ultra-strong magnetic field $\sim 10^{19}$ G,the intersection phase appears at $\sim10^{17}$ G, which is more realistic in neutron stars.

hep-ph↗

arXiv2025

Dynamical de Sitter conjecture and quintessence model

The de Sitter conjecture yields a severe bound on possible vacua for a consistent quantum gravity. We extend the de Sitter conjecture by taking into account dynamics of the scalar field. We then apply such an extended de Sitter conjecture to a quintessence model of inflation for which dynamics of the scalar field is essential, and obtain an allowed region of parameters of the scalar potential wider than previously considered cases with the conventional de Sitter conjecture. The new bounds in the swampland conjecture could have implications in several situations to construct compactification models.

hep-th↗

arXiv2025

Creation of domain-wall skyrmions in chiral magnets with Landau-Lifshitz-Gilbert dynamics and demagnetization

Absorption of an isolated bulk magnetic skyrmion into an empty domain wall in a chiral ferromagnetic system is studied using the Landau-Lifshitz-Gilbert equation with and without the demagnetization effect taken into account. The full phase diagram of creation versus repulsion or annihilation is mapped out in case of both Bloch-type and N\'eel-type DMI, with and without demagnetization. Finally, the unstable domain wall, realizable with a setup of several external magnets, contains the theoretical possibility of producing a 1-dimensional version of the Kibble-Zurek mechanism, which in turn can create a number of skyrmion-anti-skyrmion pairs engulfed in the domain wall: We denote them domain-wall-skyrmion-anti-domain-wall-skyrmion pairs.

cond-mat.mes-hall↗

arXiv2025

Chiral non-Abelian domain walls in the Ginzburg-Landau theory

In this paper, we study chiral non-Abelian domain walls in a phase of unconventional vacua of the Ginzburg-Landau model for dense QCD, by considering a wider range of parameters space not directly deduced from QCD. The phase is characterized by asymmetric vacuum-expectation values (VEVs), for example with the left scalar field, corresponding to the left quark-quark condensate, having a nonvanishing VEV and the right field having a vanishing one. The domain wall soliton interpolates between this vacuum and another where the left and right scalar fields switch roles. We study this formal possibility, but not any mechanism to generate these vacua non-perturbatively at finite density or finite temperature. Using a strong-coupling, or sigma-model limit, we are able to reduce the full dynamical complex matrix valued equations of motion to the sine-Gordon, a generalization of the sine-Gordon and a generalization of the double sine-Gordon equations. In this limit, we prove nonexistence of domain walls in one of the vacua studied here and we find full numerical computations to converge to the sigma-model limit for many cases, with some exceptions that we discuss.

hep-th↗

arXiv2025

Magnetic D-brane solitons: skyrmion strings ending on a N\'eel wall in chiral magnets

Magnetic skyrmions extended to three dimensions form string-like objects whose fundamental role remains largely unexplored. We show that skyrmion strings can terminate on a N\'eel-type domain wall (DW), realizing a magnetic analogue of a Dirichlet(D)-brane soliton. While an isolated N\'eel DW tends to rotate into a Bloch DW, the N\'eel DW is stabilized when a skyrmion string ends on it, by being transformed into a trumpet. Unlike field-theory D-branes, the Bloch-type DMI produces linear rather than logarithmic DW bending, and the strings retain finite width far from the DW, circumventing singular behavior. Furthermore, the repulsive interaction between strings allows periodic multi-junction solutions, yielding a square lattice of alternating strings and local DW deformations as well as separating Bloch points. These results establish magnetic skyrmion strings as fundamental strings that can end on a D-brane.

cond-mat.mes-hall↗

arXiv2025

Baryons as linked vortices in QCD matter with isospin asymmetry

We investigate a baryonic structure in low-energy QCD via a model-independent way using the chiral perturbation theory at the leading order, in the presence of the baryon chemical potential $μ_B$, the isospin chemical potential $μ_I$, and the electromagnetic coupling. For such a scenario in the chiral limit, it has been known that the neutral pion winds like in the chiral soliton lattice, confined within an Abrikosov-Nielsen-Olesen (ANO) vortex of the charged pions. This structure undergoes a drastic transformation when the pion mass is introduced, i.e., both charged and neutral pions condense in the bulk, allowing two distinct types of vortices: the charged pions constitute a local ANO-like vortex, while the neutral pion configures a global vortex which is further attached to a domain wall also known as the chiral soliton. Remarkably, the ANO vortex forms a topological linking with the closed global vortex line, when $μ_B$ exceeds its critical value as a function of $μ_I$. The linking number has the physical meaning of the baryon number in view of the Wess-Zumino-Witten term. In this sense, the linked configuration realizes a stable Skyrmion-type solution, but innovatively without the Skyrme term. We therefore propose a novel phase of dense baryonic matter comprised of such vortices, which shall play a role in the low-energy QCD phase diagram.

hep-ph↗

arXiv2025

Domain Wall Networks as Skyrmion Crystals in Chiral Magnets

We theoretically investigate the ground states of a chiral magnet with a square anisotropy and show that it supports domain wall networks as stable ground states. A domain wall junction in the domain wall network turns out to be a skyrmion with half topological charge and, therefore, the found domain wall network has a second topological nature, a skyrmion crystal. More specifically, we present a ground-state phase diagram of the chiral magnet with varying anisotropy parameters consisting of skyrmion lattices, chiral soliton lattices, and ferromagnetic states. In the presence of the square anisotropy, the skyrmion crystal forms a domain wall network. The size of domains in the domain wall network is shown to be tunable by an external magnetic field, offering a way to realize experimentally detectable domain wall networks.

cond-mat.mes-hall↗

arXiv2025

Creation of domain-wall Skyrmions in chiral magnets

We study the capture of a magnetic Skyrmion into a domain wall (DW) structure in chiral magnets and find that in the respective ground states of the DW and the Skyrmion, they repel each other. This means that an isolated magnetic Skyrmion cannot a priori enter the DW and become a DW-Skyrmion. However, rotating the DW's phase away from the stable phase may cause the successful capture and hence creation of a stable bound state of a magnetic Skyrmion and a DW: the DW-Skyrmion. At certain distances, the DW may also destroy the magnetic Skyrmion by inducing shrinkage of the latter. This happens as the isolated magnetic Skyrmion has negative DMI energy, whereas the DW-Skyrmion has positive DMI energy; in a finite range from the DW, the magnetic Skyrmion can be pushed to have vanishing DMI energy, for which it collapses to a point. En passant, we find the possibility of pair creation of a Skyrmion anti-DW-Skyrmion pair and a creation of more than one DW-Skyrmions by a Kibble-like mechanism.

cond-mat.mes-hall↗

arXiv2025

Fractional instantons in 2d $\mathbb{C}P^{N-1}$ model and 4d Yang-Mills theory with 't Hooft twists

We derive the explicit formula for fractional BPS lumps (or fractional instantons) in the $\mathbb{C}P^{N-1}$ nonlinear sigma model on a two-dimensional torus under various shift-clock twisted boundary conditions. After regularizing the $\mathbb{C}P^{N-1}$ model by an $N$-component Abelian-Higgs model, those twisted boundary conditions introduce nontrivial 't~Hooft fluxes $p/N$ for the $U(1)$ gauge field, and the topological charge becomes fractionalized as $k+p/N\in \mathbb{Z}+p/N$. The moduli space is globally determined as the $\mathbb{C}P^{Nk+p-1}$-fiber bundle on a $2$-torus, which is a Kähler manifold of complex dimension $Nk + p$ as predicted by the index theorem. We present two different parametrizations of the moduli space: one of them immediately identifies the small-lump singularity appearing in the $\mathbb{C}P^{N-1}$ limit, while the other makes the modular invariance manifest. We also discuss the implications of our finding for the $4$d $SU(N)$ Yang-Mills theory on the $4$-torus with 't~Hooft twists. By tuning the aspect ratio of the 4-torus, fractional instantons in the $\mathbb{C}P^{N-1}$ model with a non-Fubini-Study metric are obtained through the dimensional reduction of $4$d Yang-Mills theory, whose moduli space coincides with the one obtained for the standard $\mathbb{C}P^{N-1}$ model as complex manifolds.

hep-th↗

arXiv2025

Phase Boundary of Nuclear Matter in Magnetic Field

Nuclear matter with a strong magnetic field is prevalent inside neutron stars and heavy-ion collisions. In a sufficiently large magnetic field the ground state is either a chiral soliton lattice (CSL), an array of solitons of the neutral pion field, or a domain-wall Skyrmion phase in which Skyrmions emerge inside the chiral solitons. In the region of large chemical potential and a magnetic field lower than its critical value for CSL, a Skyrmion crystal is expected to take up the ground state based on the chiral perturbation theory at the next leading order. We determine the phase boundary between such a Skyrmion crystal and the QCD vacuum. There was a conjecture that a magnetic field deforms the Skyrmion into a pancake shape whose boundary is a superconducting ring of charged pions. In contrast, through the exact Skyrmion solution, we find that the pancake conjecture holds approximately in a strong magnetic field, but fails for a weak one. We also validate that a Skyrmion would shrink to null without the Skyrme term, although Derrick's scaling law is modified by a background magnetic field, and the stability at the leading order is not ruled out in theory.

hep-ph↗