arXiv subjects

Muneto Nitta

Publications and source records attributed to Muneto Nitta.

At least 19 recordsLinked to original sources

arXiv2026

Stable Electroweak Strings and Nambu Monopoles Nested at Inert-Higgs Interfaces

Electroweak $Z$ strings are generally unstable, and their Nambu-monopole endpoints lack topological protection in the bulk. Using degenerate inert and inert-like Higgs vacua as a solvable reference, we show that their interface supports both defects. The analytic interface carries a normalizable $SU(2)$ relative-orientation field. Its effective theory supports locally stable unit-flux $Z$ strings in a one-vacuum phase and fractional $Z$ strings in a two-vacuum phase. The fractional string carries an $S^2$ orientation field; a Nambu monopole is a second kink between symmetry-related, equal-tension $Z$ strings. We identify phases in which Nambu monopoles are confined or deconfined within the interface: in the confined phase, their $Z$ flux is concentrated into fractional strings, whereas in the deconfined phase, the monopole becomes a vortex within the interface and its $Z$ flux spreads radially through the interface. The electromagnetic magnetic field extends outside the interface in both phases. We determine analytic string profiles, effective-theory stability regions, and the unchanged electromagnetic magnetic charge across this confinement transition.

hep-ph↗

arXiv2026

Vortex clusters and vortex-filled bubbles in a modified Abelian-Higgs model

We investigate a single-component Abelian-Higgs model with an eighth-order scalar potential whose vacuum manifold consists of two disconnected circles. The model supports two species of vortices and domain walls interpolating between the two vacuum components. We find type-1.5-like behavior characterized by nonmonotonic intervortex interactions and bound states of spatially separated vortices. Inner-vacuum vortices form clusters through short-range repulsion and long-range attraction, whereas outer-vacuum vortices form vortex-filled bubbles in which a closed domain wall confines multiple inner-vacuum-vortex cores. We construct the domain wall analytically, derive the asymptotic vortex-wall interactions, and analyze the fluctuation spectra of coincident multivortices to identify their splitting instabilities.

hep-th↗

arXiv2026

The stability of non-Abelian $A_4$ vortices in $SO(3)$ gauge theory

We study the linear energetic stability of non-Abelian vortices in an $SO(3)$ gauge-Higgs theory with residual gauge group $A_4$. In our previous work, we identified two families of such vortices associated with order-two and order-three elements of $A_4$, and found Bogomol'nyi--Prasad--Sommerfield-like behavior at special ratios of the Higgs and gauge-boson mass scales. Here, we investigate their stability against $SO(3)$ gauge and Higgs perturbations by analyzing the second order variation of the vortex tension using analytical and numerical methods. In particular, when all relevant mass scales are equal, we prove linear stability for all vortices in the order-three family. By contrast, at the same mass point, we prove that a vortex in the order-two family is unstable. Thus, although both vortex families exhibit Bogomol'nyi--Prasad--Sommerfield-like behavior in their reduced equations at this mass point, their stability properties in the full $SO(3)$ theory are qualitatively different.

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 $\vec{B} \cdot \vec{\nabla} ϕ$ and $\vecΩ \cdot \vec{\nabla} ϕ$, where $ϕ$ denotes $π^0$, $η$, or $η'$. These results are relevant to chiral soliton lattices in dense rotating matter.

hep-th↗

arXiv2026

From Nested Soliton Crystals to Skyrmion Crystals in Chiral Magnets

We perform an exhaustive study of the parameter space of the chiral magnetic model with a Dzyaloshinskii-Moriya interaction, an in-plane anisotropy term and an out-of-plane Zeeman magnetic field. We map out the phase diagram for the model and find a chiral soliton lattice hosted on a chiral soliton lattice as the ground state in a particular corner of the phase diagram. There is a smooth crossover, as opposed to a phase transition, to the skyrmion crystal lattice phase. Finally, we also discover excited composite soliton states such as an anti-skyrmion coexisting with a bimeron or an anti-bimeron.

cond-mat.mes-hall↗

arXiv2026

Fractional Superfluid Vortices and Worldsheet Wess--Zumino--Witten Models in Two-Color QCD and $Sp(2N)$ Gauge Theories

We study superfluid vortices in two-color QCD and more general pseudoreal gauge theories with even flavor number $N_f=2m$ at finite baryon density. The antisymmetric diquark condensate admits fractional minimal vortices with baryon-phase winding $ν=1/m$, corresponding to $1/m$ of the conventional circulation quantum, each localizing an $Sp(2)\simeq SU(2)$ core sector. For vortices embedded in mutually orthogonal flavor planes, the leading-order chiral action factorizes exactly. Off-diagonal flavor zero modes are non-normalizable at finite separation but become localized at coincidence, enhancing the normalizable sector from $[Sp(2)]^m$ to $Sp(2m)$. For fundamental fermions of an $Sp(2N)$ gauge theory, the bulk Wess--Zumino--Witten (WZW) term descends compatibly: a cluster of $n$ coincident minimal vortices carries an $Sp(2n)_N$ WZW theory, while a flavor-symmetric vortex with positive integer baryon-phase winding $ν$ carries $Sp(2m)_{Nν}$. At unit winding this yields the vortex map to $Sp(2m)_N$, with central charge $c=Nm(2m+1)/(N+m+1)$ at the WZW fixed point, and suggests a broader nonsupersymmetric four-dimensional/two-dimensional correspondence.

hep-th↗

arXiv2026

Magnetic Q-balls

We study charged soliton branches in quasi-one-dimensional chiral magnetic systems with Dzyaloshinskii--Moriya (DM) interaction, easy-axis anisotropy, and Zeeman coupling. The same static magnetic functional is equipped with two different dynamical completions: an antiferromagnetic model with second-order time derivatives and a ferromagnetic model with Berry-phase dynamics. On the helical branch selected by the static DM interaction, the problem reduces to an analytically tractable one-dimensional system for the polar angle of the order parameter. We derive the existence conditions for polar Q-balls from the curvature of the reduced effective potential and the presence of a nonzero turning point. In the antiferromagnetic case, the allowed frequency window is symmetric and can be completely closed by the combined effect of the DM coupling and the Zeeman field. At zero Zeeman field, the same reduction also supports antiferromagnetic Q-kinks, for which we obtain explicit profiles, charges, energies, and reduced-sector fission criteria. In the ferromagnetic case, the Berry phase makes the rotation frequency act as a shifted Zeeman field. As a result, north- and south-pole charged droplets are selected by opposite signs of the shifted rotation. We also show that a formal pole-to-pole solution of the ferromagnetic mechanical problem does not generally correspond to a finite-energy magnetic soliton, because the Berry term does not renormalize the physical Hamiltonian. These results clarify how charged-soliton mechanisms depend on the underlying magnetic dynamics, even when the static chiral energy is the same.

cond-mat.mes-hall↗

arXiv2026

Emergent Conformal Symmetry on Superfluid Vortices in Two-Color QCD and Pseudoreal Gauge Theories

Two-color QCD provides a unique first-principles laboratory for strongly interacting matter at finite baryon density, where a diquark condensate realizes a baryonic superfluid. We investigate the internal physics of its quantized superfluid vortices in the chiral limit. We find that a vortex localizes an exact and normalizable $S^3\simeq SU(2)$ family of pion modes. Remarkably, the bulk Wess--Zumino--Witten (WZW) term induces a quantized WZW term for these modes, driving the vortex theory in the infrared to the $SU(2)_1$ WZW conformal field theory with central charge $c=1$. Thus a strongly coupled conformal theory emerges on a vortex in a nonconformal bulk theory. The mechanism extends to pseudoreal $Sp(2N)$ gauge theories, where the corresponding minimal vortex theory flows to $SU(2)_N$, with the level directly encoding the microscopic anomaly coefficient.

hep-th↗

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

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

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 $π_3(S^3)$. 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

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 $π_1(SO(3)/A_4)\simeq \widetilde{A}_4$, 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

Magnetic D-brane solitons: skyrmion strings ending on a Néel 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 Néel-type domain wall (DW), realizing a magnetic analogue of a Dirichlet(D)-brane soliton. While an isolated Néel DW tends to rotate into a Bloch DW, the Néel 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↗

arXiv2026

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 Néel-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↗

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

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↗