arXiv subjects

Mitsutoshi Fujita

Publications and source records attributed to Mitsutoshi Fujita.

At least 19 recordsLinked to original sources

arXiv2026

Confining potential in holographic bottom-up QCD from WKB

By using the \emph{Rydberg--Klein--Rees} (RKR) formulas to solve the inverse Schrödinger problem, we found a confining bottom-up potential from a given eigenvalue spectrum. To illustrate this methodology, we consider the vector meson spectrum derived in the D3/D7 system as input data to derive the corresponding bottom-up confining potential that resembles the geometric structure of the so-called hardwall model. We compute some properties for this new bottom-up model, including the thermal deconfinement phase transition, the $ρ$ radial Regge trajectory, and the configurational entropy.

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arXiv2026

Geometric entropy and time-like entanglement entropy on a rotating BTZ black hole

In this paper, we analyze the double Wick rotation of a rotating BTZ black hole and the entanglement entropy. We derive the transition matrix dual to the double Wick-rotated BTZ black hole, which has the usual shape at an imaginary chemical potential. In the dual gravity side, the double Wick rotated BTZ black hole, which is obtained as a quotient, is equal to a rotating BTZ black hole after the coordinate transformation and the identification of periodicity. The geometric entropy and time-like entanglement entropy are reproduced by the identification. New Lorentzian entanglement growth is defined by the coefficient of linear growth of time-like entanglement entropy.

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arXiv2026

The influence of Wilson lines on heavy quark anti-quark potential and mass

The holographic heavy quark potential is investigated via holographic Wilson loops in the AdS soliton with gauge potential. We analyze two types of holographic Wilson loops. {In the first type, holographic heavy quark potential shows the area law behavior. In the second type, the potential becomes zero at a critical length and physics analogous to the dissociation occurs. The mass of heavy quarkonia and the binding energy are examined.} Lastly, the mass of $0^{++}$ glueball-like operators dual to massless dilaton is calculated. The mass of $0^{++}$ glueball-like operator decreases with increase of the gauge potential as expected in arXiv:2309.03491 [hep-th]. The results are comparable with lattice QCD.

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arXiv2025

Notes on the double Wick rotated BTZ black hole

We analyze the double Wick rotated BTZ black hole with the Euclidean signature, which is a Riemannian manifold. We calculate thermodynamics, total energy of spacetime, and holographic two point functions in the double Wick rotated background. Results agree with those of a rotating BTZ with the same periodicity.

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arXiv2025

The effect of gluon condensate on the entanglement entropy in a holographic model

In this study, we examine the impact of the gluon condensate on holographic entanglement entropy within an Einstein-Dilaton model at both zero and finite temperatures. A critical length exists for the difference in entanglement entropy between connected and disconnected surfaces in this model, which is typically interpreted as an indicator of phase transition. As the gluon condensate increases, the critical length decreases, suggesting that confinement strengthens at zero temperature. Additionally, the entropic C-function abruptly drops to zero at the critical length, indicating the absence of entangled states. At finite temperatures, the results show that the effect of the gluon condensate on the critical length is qualitatively similar to that at zero temperature. We observe that the entropic C-function increases as a function of $L$ at finite temperature, though it exhibits competitive behaviors when the gluon condensate is large.

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arXiv2024

Moving doubly heavy baryon in a strongly coupled plasma from holography

Gauge/gravity duality is used to study properties of the doubly heavy baryon $(\mathrm{QQq})$ at finite rapidity and temperature in the heavy-ion collision. We investigate the impact of rapidity on string breaking and screening of $\mathrm{QQq}$, and compare these effects with the results for $\rm Q\bar{Q}$ in detail. Computations reveal that the string-breaking distances of $\mathrm{QQq}$ and $\rm Q\bar{Q}$ are close in the confined state and the effects of rapidity and temperature on the string breaking are not significant. An interesting result shows that $\mathrm{QQq}$ cannot be found at high enough temperatures and rapidities; however, $\rm Q\bar{Q}$ can exist under any conditions as long as the separation distance is small enough. Besides, the screening distances of $\mathrm{QQq}$ and $\rm Q\bar{Q}$ are also compared at finite rapidity and temperature. Based on the above analysis, we infer that $\rm Q\bar{Q}$ is more stable than $\mathrm{QQq}$ at finite rapidity and temperature.

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arXiv2023

Holographic renormalized Entanglement and entropic $c-$function

We compute holographic entanglement entropy (EE) and the renormalized EE in AdS solitons with gauge potential for various dimensions. The renormalized EE is a cutoff-independent universal component of EE. Via Kaluza-Klein compactification of $S^1$ and considering the low-energy regime, we deduce the $(d-1)$-dimensional renormalized EE from the odd-dimensional counterpart. This corresponds to the shrinking circle of AdS solitons, probed at large $l$. The minimal surface transitions from disk to cylinder dominance as $l$ increases. The quantum phase transition occurs at a critical subregion size, with renormalized EE showing non-monotonic behavior around this size. Across dimensions, massive modes decouple at lower energy, while degrees of freedom with Wilson lines contribute at smaller energy scales.

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arXiv2022

Nucleon D-term in holographic QCD

The D-term is one of the conserved charges of hadrons defined as the forward limit of the gravitational form factor $D(t)$. We calculate the nucleon's D-term in a holographic QCD model in which the nucleon is described as a soliton in five dimensions. We show that the form factor $D(t)$ is saturated by the exchanges of infinitely many $0^{++}$ and $2^{++}$ glueballs dual to transverse-traceless metric fluctuations on the Wick rotated AdS$_7$ black hole geometry. We refer to this phenomenon as `glueball dominance', in perfect analogy to the vector meson dominance of the electromagnetic form factors. However, the value at vanishing momentum transfer $D(t=0)$ can be interpreted as due to the exchange of pairs of pions and infinitely many vector and axial-vector mesons without any reference to glueballs. We find that the D-term is slightly negative as a result of a cancellation between the isovector and isoscalar meson contributions.

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arXiv2022

Holographic entanglement entropy of the double Wick rotated BTZ black hole

In this paper, we analyze the holographic covariant entanglement entropy in the double Wick rotated version of a rotating BTZ black hole (3 dimensional Kerr-AdS solution), where the periodicity of Euclidean time and spatial direction are changed. The dual field theory has negative energy in the Lorentzian signature. The holographic entanglement entropy agrees with its CFT counterpart, which is obtained by a conformal transformation of the correlation functions of twisted operators.

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arXiv2021

Ginzburg-Landau effective action for a fluctuating holographic superconductor

Under holographic prescription for Schwinger-Keldysh closed time contour for non-equilibrium system, we consider fluctuation effect of the order parameter in a holographic superconductor model. Near the critical point, we derive the time-dependent Ginzburg-Landau effective action governing dynamics of the fluctuating order parameter. In a semi-analytical approach, the time-dependent Ginzburg-Landau action is computed up to quartic order of the fluctuating order parameter, and first order in time derivative.

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arXiv2020

Thermodynamical property of entanglement entropy and deconfinement phase transition

We analyze the holographic entanglement entropy in a soliton background with Wilson lines and derive a relation analogous to the first law of thermodynamics. The confinement/deconfinement phase transition occurs due to the competition of two minimal surfaces. The entropic c function probes the confinement/deconfinement phase transition. It is sensitive to the degrees of freedom (DOF) smaller than the size of a spatial circle. When the Wilson line becomes large, the entropic c function becomes non-monotonic as a function of the size and does not satisfy the usual c-theorem. We analyze the entanglement entropy for a small subregion and the relation analogous to the first law of thermodynamics. For the small amount of Wilson lines, the excited amount of the entanglement entropy decreases from the ground state. It reflects that confinement decreases degrees of freedom. We finally discuss the second order correction of the holographic entanglement entropy.

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arXiv2019

Holographic subregion complexity of a 1+1 dimensional $p$-wave superconductor

We analyze the holographic subregion complexity in a $3d$ black hole with the vector hair. This $3d$ black hole is dual to a $1+1$ dimensional $p$-wave superconductor. We probe the black hole by changing the size of the interval and by fixing $q$ or $T$. We show that the universal part is finite across the superconductor phase transition and has competitive behaviors different from the finite part of entanglement entropy. The behavior of the subregion complexity depends on the gravitational coupling constant divided by the gauge coupling constant. When this ratio is less than the critical value, the subregion complexity increases as temperature becomes low. This behavior is similar to the one of the holographic $1+1$ dimensional $s$-wave superconductor arXiv:1704.00557. When the ratio is larger than the critical value, the subregion complexity has a non-monotonic behavior as a function of $q$ or $T$. We also find a discontinuous jump of the subregion complexity as a function of the size of the interval. The subregion complexity has the maximum when it wraps the almost entire spatial circle. Due to competitive behaviors between normal and condensed phases, the universal term in the condensed phase becomes even smaller than that of the normal phase by probing the black hole horizon at a large interval. It implies that the formed condensate decreases the subregion complexity like the case of the entanglement entropy.

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arXiv2019

Kibble-Zurek Scaling in a Holographic p-wave Superconductor

We study the Kibble-Zurek mechanism in a 2d holographic p-wave superconductor model with a homogeneous source quench on the critical point. We derive, on general grounds, the scaling of the Kibble-Zurek time, which marks breaking-down of adiabaticity. It is expressed in terms of four critical exponents, including three static and one dynamical exponents. Via explicit calculations within a holographic model, we confirm the scaling of the Kibble-Zurek time and obtain the scaling functions in the quench process. We find the results are formally similar to a homogeneous quench in a higher dimensional holographic s-wave superconductor. The similarity is due to the special type of quench we take. We expect differences in the quench dynamics if the condition of homogeneous source and dominance of critical mode are relaxed.

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arXiv2019

Effective Hopping in Holographic Bose and Fermi-Hubbard Models

In this paper, we analyze a proposed gravity dual to a $SU(N)$ Bose-Hubbard model, as well as construct a holographic dual of a $SU(N)$ Fermi-Hubbard model from D-branes in string theory. In both cases, the $SU(N)$ is dynamical, i.e. the hopping degrees of freedom are strongly coupled to $SU(N)$ gauge bosons which themselves are strongly interacting. The vacuum expectation value (VEV) of the hopping term (i.e. the hopping energy) is analyzed in the gravity dual as a function of the bulk mass of the field dual to the hopping term, as well as of the coupling constants of the model. The bulk mass controls the anomalous dimension (i.e. the critical exponent) of the hopping term in the $SU(N)$ Bose-Hubbard model. We compare the hopping energy to the corresponding result in a numerical simulation of the ungauged $SU(N)$ Bose-Hubbard model. We find agreement when the hopping parameter is smaller than the other couplings. Our analysis shows that the kinetic energy increases as the bulk mass increases, due to increased contributions from the IR. The holographic Bose-Hubbard model is then compared with the string theory construction of a $SU(N)$ Fermi-Hubbard model. The string theory construction makes it possible to describe fluctuations around a half-filled state in the supergravity limit, which map to ${\cal O}(1)$ occupation number fluctuations in the Fermi-Hubbard model at half filling. Finally, the VEV of the Bose-Hubbard model is shown to agree with the one of the fermionic Hubbard model with the help of a two-site version of the Jordan-Wigner transformation.

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arXiv2017

Holographic entanglement entropy of a $1+1$ dimensional $p$-wave superconductor

We examine the behavior of entanglement entropy of a subsystem $A$ in a fully backreacted holographic model of a $1+1$ dimensional $p$ wave superconductor across the phase transition. For a given temperature, the system goes to a superconducting phase beyond a critical value of the charge density. The entanglement entropy, considered as a function of the charge density at a given temperature, has a cusp at the critical point. In addition, we find that there are three different behaviors in the condensed phase, depending on the subsystem size. For a subsystem size $l$ smaller than a critical size $l_{c1}$, entanglement entropy continues to increase as a function of the charge density as we cross the phase transition. When $l$ lies between $l_{c1}$ and another critical size $l_{c2}$ the entanglement entropy displays a non-monotonic behavior, while for $l > l_{c2}$ it decreases monotonically. At large charge densities entanglement entropy appears to saturate. The non-monotonic behavior leads to a novel phase diagram for this system.

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arXiv2016

Holographic Chern-Simons Defects

We study SU(N) Yang-Mills-Chern-Simons theory in the presence of defects that shift the Chern-Simons level from a holographic point of view by embedding the system in string theory. The model is a D3-D7 system in Type IIB string theory, whose gravity dual is given by the AdS soliton background with probe D7-branes attaching to the AdS boundary along the defects. We holographically renormalize the free energy of the defect system with sources, from which we obtain the correlation functions for certain operators naturally associated to these defects. We find interesting phase transitions when the separation of the defects as well as the temperature are varied. We also discuss some implications for the Fractional Quantum Hall Effect and for two-dimensional QCD.

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arXiv2015

Hydrodynamics in 1+1 dimensions from Maxwell-Chern-Simons theory in AdS_3

In this presentation we review our work on Abelian Maxwell-Chern-Simons theory in three-dimensional AdS black brane backgrounds, with both integer and non-integer Chern-Simons coupling. Such theories can be derived from several string theory constructions, and we found exact solutions in the low frequency, low momentum limit (omega, k << T, the hydrodynamic limit). Our results are translated into correlation functions of vector operators in the dual strongly coupled 1+1-dimensional quantum field theory with a chiral anomaly at non-zero temperature T, via the holographic correspondence. The applicability of the hydrodynamic limit is discussed, together with the comparison between an exact field theoretic computation and the found holographic correlation functions in the conformal case.

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arXiv2015

From Maxwell-Chern-Simons theory in $AdS_3$ towards hydrodynamics in 1+1 dimensions

We study Abelian Maxwell-Chern-Simons theory in three-dimensional $AdS$ black hole backgrounds for both integer and non-integer Chern-Simons coupling. Such theories can be derived from various string theory constructions, which we review in the present work. In particular we find exact solutions in the low frequency, low momentum limit, $ω, k \ll T$(hydrodynamic limit). Using the holographic principle, we translate our results into correlation functions of vector and scalar operators in the dual strongly coupled 1+1-dimensional quantum field theory with a chiral anomaly at non-zero temperature $T$. Starting from the conformal case we show applicability of the hydrodynamic limit and discuss extensions to the non-conformal case. Correlation functions in the conformal case are compared to an exact field theoretic computation.

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