We study a membrane -- anti-membrane system in Matrix theory. It in fact exhibits the tachyon instability. By suitably representing this configuration, we obtain a (2+1)-dimensional U(2) gauge theory with a 't Hooft's twisted boundary condition. We identify the tachyon field with a certain off-diagonal element of the gauge fields in this model. Taking into account the boundary conditions carefully, we can find vortex solutions which saturate the Bogomol'nyi-type bound and manifest the tachyon condensation. We show that they can be interpreted as gravitons in Matrix theory.

H. Awata S. Hirano Y. Hyakutake

We study the elliptic flow coefficient v_2(eta,b) in Au+Au collisions at sqrt(s)=200 A GeV as a function of pseudorapidity eta and impact parameter b. Using a hybrid approach which combines early ideal fluid dynamical evolution with late hadronic rescattering, we demonstrate strong dissipative effects from the hadronic rescattering stage on the elliptic flow. With Glauber model initial conditions, hadronic dissipation is shown to be sufficient to fully explain the differences between measured v_2 values and ideal hydrodynamic predictions. Initial conditions based on the Color Glass Condensate model generate larger elliptic flow and seem to require additional dissipation during the early quark-gluon plasma stage in order to achieve agreement with experiment.

Tetsufumi Hirano Ulrich W. Heinz Dmitri Kharzeev Roy Lacey Yasushi Nara

Double extortion ransomware attacks have become mainstream since many organizations adopt more robust and resilient data backup strategies against conventional crypto-ransomware. This paper presents detailed attack stages, tactics, procedures, and tools used in the double extortion ransomware attacks. We then present a novel detection method using low-level storage and memory behavioral features and network traffic features obtained from a thin hypervisor to establish a defense-in-depth strategy for when attackers compromise OS-level protection. We employed the lightweight \emph{Kitsune} Network Intrusion Detection System (NIDS)'s network feature to detect the data exfiltration phase in double extortion ransomware attacks. Our experimental results showed that the presented method improved by 0.166 in the macro F score of the data exfiltration phase detection rate. Lastly, we discuss the limitations of the presented method and future work.

Manabu Hirano Ryotaro Kobayashi

We study coexistence of CV-QKD and 7 classical 12.5 Gbit/s on-off keying channels in WDM transmission over the C-band. We demonstrate key generation with a distilled secret key rate between 20 to 50 kbit/s in experiments running continuously over 24 hours.

Tobias A. Eriksson Takuya Hirano Motoharu Ono Mikio Fujiwara Ryo Namiki Ken-ichiro Yoshino Akio Tajima Masahiro Takeoka Masahide Sasaki

We investigate the rapidity dependence of the elliptical flow in heavy ion collisions at 200 GeV (cms), by employing a three-dimensional hydrodynamic evolution, based on different initial conditions, and different freeze-out scenarios. It will be shown that the form of pseudo-rapidity ($\eta$) dependence of the elliptical flow is almost identical to space-time-rapidity ($\eta_{s}$) dependence of the initial energy distribution, independent of the freeze-out prescriptions.

K. Werner T. Hirano Iu. Karpenko T. Pierog S. Porteboeuf M. Bleicher S. Haussler

AC susceptibility measurements have been carried out on superconducting LaO1-xFxFeAs for x=0.07 and 0.14 under He-gas pressures to about 0.8 GPa. Not only do the measured values of dTc/dP differ substantially from those obtained in previous studies using other pressure media, but the Tc(P) dependences observed depend on the detailed pressure/temperature history of the sample. A sizeable sensitivity of Tc(P) to shear stresses provides a possible explanation.

W. Bi H. B. Banks J. S. Schilling H. Takahashi H. Okada Y. Kamihara M. Hirano H. Hosono

We sought to determine the scale of scintillation in the interstellar plasma of PSR J0437-4715. We used the Very Long Baseline Array to obtain scintillation amplitude and phase data, from dynamic spectra at 327 MHz. We observe two scales of scintillation of pulsar PSR J0437-4715, differing by more than an order of magnitude in scintillation bandwidth. The wider-bandwidth scale of scintillation that we observe indicates less scattering for this pulsar than for other nearby pulsars, except for PSR B0950+08.

C. R. Gwinn C. Hirano S. Boldyrev

A spin-1/2 frustrated two-leg ladder with four-spin exchange interaction is studied by quantized Berry phases. We found that the Berry phase successfully characterizes the Haldane phase in addition to the rung-singlet phase, and the dominant vector-chirality phase. The Hamiltonian of the Haldane phase is topologically identical to the S=1 antiferromagnetic Heisenberg chain. Decoupled models connected to the dominant vector-chirality phase revealed that the local object identified by the non-trivial ($\pi$) Berry phase is the direct product of two diagonal singlets.

I. Maruyama T. Hirano Y. Hatsugai

Electrical resistivity and magnetic susceptibility measurements under high pressure were performed on an iron-based superconductor LaFePO. A steep increase in superconducting transition temperature (Tc) of LaFePO with dTc/dP > 4 K/GPa to a maximum of 8.8 K for P = 0.8 GPa was observed. These results are similar to isocrystalline LaFeAsO1-xFx system reported previously. X-ray diffraction measurements were also performed under high pressure up to 10 GPa, where linear compressibility ka and kc are presented.

K. Igawa H. Okada K. Arii H. Takahashi Y. Kamihara M. Hirano H. Hosono S. Nakano T. Kikegawa

We present a new model of gravity which explicitly breaks Lorentz-invariance by the introduction of a unit time-like vector field, thereby giving rise to an extra (scalar) degree of freedom. We discuss its cosmology, exact solutions and the dynamics of the scalar mode. We show that it predicts inflation without an inflaton and admits the black hole solutions of General Relativity (GR). We argue that the scalar mode is well behaved and contains none of the pathologies previously found in similar models.

Flavio S. Coelho Carlos Herdeiro Shinji Hirano Yuki Sato