122884910
Temporal chiral spiral in QCD in the presence of strong magnetic fields
Vacuum properties of quantum chromodynamics in strong magnetic and nite electric elds are investigated. We show that when a uniform electric eld is instantaneously applied in the parallel direction to a strong magnetic eld, it induces temporal oscillation of the scalar and pseudoscalar condensates. This is a temporal analog to the chiral spiral. The oscillation originates with the propagation of the collective mode, which is protected by the axial anomaly and thus is nondissipative.
119220877
Lattice study of the chiral magnetic effect in a chirally imbalanced matter
We investigate the chiral magnetic effect by lattice QCD with a chiral chemical potential. In a chirally imbalanced matter, we obtain a finite induced current along an external magnetic field. We analyze the dependence on the lattice spacing, the temperature, the spatial volume, and the fermion mass. The present result indicates that the continuum limit is important for the quantitative argument of the strength of the induced current.
56393007
Lattice QCD simulation at finite chiral chemical potential
Chiral chemical potential does not cause the sign problem in the Monte Carlo simulation of lattice QCD. Using the chiral chemical potential, we study the chiral magnetic effect in two-flavor full QCD. We show that a strong external magnetic field induces an electric current in a chirally imbalanced QCD matter. The qualitative feature of the induced current is consistent with an analytical prediction.
14791294
Heavy-heavy-light quark potential in SU(3) lattice QCD
Abstract We perform the first study for the heavy–heavy–light quark ( QQq ) potential in SU ( 3 ) quenched lattice QCD with the Coulomb gauge. The calculations are done with the standard gauge and O ( a ) -improved Wilson fermion action on the 16 4 lattice at β = 6.0 . We calculate the energy of QQq systems as the function of the distance R between the two heavy quarks, and find that the QQq potential is well described with a Coulomb plus linear potential form up to the intermediate distance R ⩽ 0.8 fm . Compared to the static three-quark case, the effective string tension between the heavy quarks is significantly reduced by the finite-mass valence quark effect. This reduction is considered to be a general property for baryons.
118187023
Lattice QCD Analysis for Gluons
Nonperturbative properties of gluons are studied in SU(3) lattice QCD at the quenched level. The first subject is a functional-form analysis of the gluon propagator $D_{\mu\nu}^{ab}(x)$ in the Landau gauge. We find that the gluon propagator $D_{\mu\mu}^{aa}(r)$ obtained in lattice QCD is well described by the four-dimensional (4D) Yukawa-type function $e^{-mr}/r$ with $m \simeq 600$MeV for the Euclidean 4D distance $r = 0.1 \sim 1.0$ fm. In momentum space, the gluon propagator $\tilde D_{\mu\mu}^{aa}(p^2)$ ($p= 0.5 \sim 3$ GeV) is found to be well approximated with a new-type propagator of $(p^2+m^2)^{-3/2}$, which corresponds to 4D Fourier image of the Yukawa-type function. Associated with the Yukawa-type gluon propagator, we derive analytical expressions for the zero-spatial-momentum propagator $D_0(t)$, the effective mass $M_{\rm eff}(t)$, and the spectral function $\rho(\omega)$ of the gluon field. The mass parameter $m$ turns out to be the infrared effective mass of gluons. The obtained gluon spectral function $\rho(\omega)$ is almost negative-definite for $\omega >m$, except for a positive $\delta$-functional peak at $\omega=m$. The second subject is a lattice-QCD determination of the relevant gluonic momentum-component for color confinement. As a remarkable fact, the string tension is found to be almost unchanged even after cutting off the high-momentum gluon component above 1.5 GeV in the Landau gauge. In fact, the relevant gluonic scale for color confinement is concluded to be below 1.5 GeV.
118515420
Charged vector mesons in a strong magnetic field
We show that charged vector mesons cannot be condensed by a magnetic field. Although some hadron models predict the charged vector meson condensation in a strong magnetic field, we prove, by means of the Vafa-Witten theorem, that this is not the case in QCD. We also perform the numerical analysis for the meson mass and condensation in lattice QCD. The lattice QCD data confirm no charged vector meson condensation in a magnetic field.
19387199
In-Line Control in T2K Proton Beam Line Magnet Safety System
Magnet Safety Systems (MSS) frequently use quench detection based on voltage measurement, in order to protect superconducting magnets. Disconnecting quench detection cables and using a voltage generator to simulate quench voltages is a good way to check the system. This paper describes another method, with a hardware and software in-line control system, used to periodically check the MSS of the 28 superconducting magnets of the T2K proton beam line, at J-PARC. With in-line control, an isolated simulation voltage is added to each real input voltage of the detectors, without disconnecting quench detection cables. In-line control can also check if quench detection cables are connected or not, and if a detection wire is broken. In-line control is realized with additional electronic hardware and software on the MSS electronic boards and with a connection to a PC with a specific software and Graphic User Interface running under Windows. Nevertheless, quench detection and safety actions are always based on hardware only. Extreme care is taken so that in-line control cannot prevent the MSS to protect the magnet system, even if software stops running. Other remote functions are also available with this system, like monitoring of analog and logical signals and setting of detection and electronic parameters, if needed.
113855195
Studies of Fabrication Procedure of 9-cell SRF Cavity for ILC Mass-production at KEK.
We had been constructing a new facility for the fabrication of superconducting RF cavity at KEK from 2009 to 2011. In the facility, we have installed a deepdrawing machine, a half-cup trimming machine, an electron-beam welding machine, and a chemical etching room in one place. We started the studies on the fabrication of 9-cell cavity for International Linear Collier (ILC) using this facility. The studies are focusing on the cost reduction with keeping high performance of cavity, and the goal is the establishment of mass-production procedure for ILC. We already finished the fabrication of two 9-cell cavities in this facility. This article reports the current status of the studies.
21013020
Conduction Cooling Test of a Splittable Quadrupole for ILC Cryomodules
A superconducting splittable quadrupole magnet was designed at Fermilab for use in ILC-style cryomodules, in which the magnet is to be assembled around the beam tube to avoid contaminating the ultraclean superconducting RF beam volume. This quadrupole was built and first tested in a liquid helium bath environment at Fermilab, where its quench and magnetic performance were characterized. The device is intended to be cooled by conduction when installed in cryomodules, so a separate test was made at KEK where an appropriate conduction cooling test facility exists. We present results of the thermal performance of the magnet in the conduction cooling mode, and discuss its excitation characteristics in this operating mode.