arXiv subjects

Yusuke Shimada

Publications and source records attributed to Yusuke Shimada.

7 recordsLinked to original sources

arXiv2026

Polyakov-loop potential of accelerated gluonic matter and thermodynamic subtleties

We study the one-loop Polyakov-loop effective potential in pure gluonic matter under constant acceleration. We perform the computation in both the Euclidean Rindler spacetime and the optical spacetime, which are related via a conformal transformation. The results from the two formulations correspond to physically different observables, and we clarify their connection to specific components of the energy-momentum tensor. This identification resolves a discrepancy previously noted for fields on conical backgrounds. For the Polyakov-loop expectation value, we should minimize the effective potential computed in the optical metric formulation, which concludes that real acceleration strengthens deconfining properties. We also discuss analytic continuation from real to imaginary acceleration and find a perturbatively confined phase. We point out some suggestive similarities and differences between systems under imaginary acceleration and imaginary rotation.

hep-ph↗

arXiv2025

Imaginary Rotating Gluonic Matter at Strong Coupling

We write down an effective theory of the Polyakov loop to investigate the deconfinement phase transition of imaginary-rotating gluonic matter using the strong-coupling expansion. We find the strength of the nearest-neighbor Polyakov-loop interaction modified by the sum of contributions involving the chair-type loops along the temporal direction. Our results show that the deconfinement transition temperature increases with increasing imaginary angular velocity, which agrees with the predictions from the models and the high-temperature perturbative calculations.

hep-ph↗

arXiv2025

Analyzing the Higgs-confinement transition with non-local operators on the lattice

We study non-local operators for analyzing the Higgs-confinement phase transition in lattice gauge theory. Since the nature of the Higgs-confinement phase transition is topological, its order parameter is the expectation value of non-local operators, such as loop and surface operators. There exist several candidates for the non-local operators. Adopting the charge-2 Abelian Higgs model, we test numerical simulation of conventional ones, the Polyakov loop and the 't Hooft loop, and an unconventional one, the Aharonov-Bohm phase defined by the Wilson loop wrapping around a vortex line.

hep-lat↗

arXiv2024

Inhomogeneous confinement and chiral symmetry breaking induced by imaginary angular velocity

We investigate detailed properties of imaginary rotating matter with gluons and quarks at high temperature. Previously, we showed that imaginary rotation induces perturbative confinement of gluons at the rotation center. We perturbatively calculate the Polyakov loop potential and find inhomogeneous confinement above a certain threshold of imaginary angular velocity. We also evaluate the quark contribution to the Polyakov loop potential and confirm that spontaneous chiral symmetry breaking occurs in the perturbatively confined phase.

hep-ph↗

arXiv2024

Giant tunability of magnetoelasticity in Fe$_4$N system: Platform for unveiling correlation between magnetostriction and magnetic damping

Flexible spintronics has opened new avenue to promising devices and applications in the field of wearable electronics. Particularly, miniaturized strain sensors exploiting the spintronic function have attracted considerable attention, in which the magnetoelasticity linking magnetism and lattice distortion is a vital property for high-sensitive detection of strain. This paper reports the demonstration that the magnetoelastic properties of Fe$_4$N can be significantly varied by partially replacing Fe with Co or Mn. The high quality Fe$_4$N film exhibits large negative magnetostriction along the [100] direction ($\lambda_{100}$) of -121 ppm while Fe$_{3.2}$Co$_{0.8}$N shows $\lambda_{100}$ of +46 ppm. This wide-range tunability of $\lambda_{100}$ from -121 to +46 across 0 allows us to thoroughly examine the correlation between the magnetoelasticity and other magnetic properties. The strong correlation between $\lambda_{100}$ and magnetic damping ($\alpha$) is found. The enhanced extrinsic term of $\alpha$ is attributable to the large two magnon scattering coming from the large magnetostriction. In addition, the density of states at the Fermi level plays a primal role to determine both $\lambda_{100}$ and the intrinsic term of $\alpha$. Thanks to the giant tunability and the bipolarity of magnetoelasticity, magnetic nitrides are candidate materials for high-sensitive spintronic strain sensors.

cond-mat.mtrl-sci↗

arXiv2022

Perturbative confinement in thermal Yang-Mills theories induced by imaginary angular velocity

We perturbatively compute the Polyakov loop potential at high temperature with finite imaginary angular velocity. This imaginary rotation does not violate the causality and the thermodynamic limit is well defined. We analytically show that the imaginary angular velocity induces the perturbatively confined phase and serves as a new probe to confinement physics. We discuss a possible phase diagram that exhibits adiabatic continuity from the perturbative confinement to the confined phase at low temperature. We also mention subtlety in the analytical continuation from imaginary to real angular velocity by imposing a causality bound.

hep-ph↗

arXiv2020

Towards a Backdoorless Network Architecture Based on Remote Attestation and Backdoor Inspection

To keep a system secure, all devices in the system need to be benign. To avoid malicious and/or compromised devices, network access control such as authentication using a credential and remote attestation based on trusted hardware has been used. These techniques ensure the authenticity and integrity of the devices, but do not mitigate risks of a backdoor embedded in the devices by the developer. To tackle this problem, we propose a novel architecture that integrates remote attestation and backdoor inspection. Specifically, the backdoor inspection result is stored in a server and the verifier retrieves and checks the backdoor inspection result when the remote attestation is performed. Moreover, we discuss issues to deploy the proposed architecture to the real world.

cs.CR↗