67846739
QCD critical point in the strong coupling lattice QCD and during black hole formation
We discuss the QCD phase diagram from two different point of view. We first investigate the phase diagram structure in the strong coupling lattice QCD with Polyakov loop effects, and show that the the chiral and Z_{N_c} deconfinement transition boundaries deviate at finite mu as suggested from large N_c arguments. Next we discuss the possibility to probe the QCD critical point during prompt black hole formation processes. The thermodynamical evolution during the black hole formation would result in quark matter formation, and the critical point in isospin asymmetric matter may be swept. (T,mu_B) region probed in heavy-ion collisions and the black hole formation processes covers most of the critical point locations predicted in recent lattice Monte-Carlo simulations and chiral effective models.
2854510
Phase diagram at finite temperature and quark density in the strong coupling limit of lattice QCD for color SU(3)
We study the phase diagram of quark matter at finite temperature ($T$) and chemical potential ($\ensuremath{\mu}$) in the strong coupling limit of lattice QCD for color SU(3). We derive an analytical expression of the effective free energy as a function of $T$ and $\ensuremath{\mu}$, including baryon effects. The finite temperature effects are evaluated by integrating over the temporal link variable exactly in the Polyakov gauge with an antiperiodic boundary condition for fermions. The obtained phase diagram shows the first and the second order phase transition at low and high temperatures, respectively, and those are separated by the tricritical point in the chiral limit. Baryon has effects to reduce the effective free energy and to extend the hadron phase to a larger $\ensuremath{\mu}$ direction at low temperatures.
119156260
Gluonic observables and the scalar spectrum of twelve-flavour QCD
We measure glueball masses and the string tension in twelve–flavour QCD, aiming at comparing the emerging gluonic spectrum to the mesonic one. When approaching the critical surface at zero quark mass, the hierarchy of masses in the different sectors of the spectrum gives a new handle to determine the existence of an infrared fixed point. We describe the details of our gluonic measurements and the results obtained on a large number of gauge configurations generated with the HISQ action. In particular, we focus on the scalar glueball and its mixing with a flavour–singlet fermionic state, which is lighter than the pseudoscalar (would–be pion) state. The results are interesting in view of a light composite Higgs boson in walking technicolor theories.
53495167
Light composite scalar in eight-flavor QCD on the lattice
In search for a composite Higgs boson (techni-dilaton) in the walking technicolor, we present our preliminary results on the first observation of a light flavor-singlet scalar in a candidate theory for the walking technicolor, the Nf=8 QCD, which was found in our previous paper to have spontaneous chiral symmetry breaking together with remnants of the conformality. Based on simulations with the HISQ-type action on several lattice sizes with various fermion masses, we find evidence of a flavor-singlet scalar meson with mass comparable to that of the Nambu-Goldstone pion in both the small fermion-mass region, where chiral perturbation theory works, and the intermediate fermion-mass region where the hyperscaling relation holds. We further discuss its chiral limit extrapolation in comparison with other states studied in our previous paper: the scalar has a mass much smaller than that of the vector meson, which is compared to the Nambu-Goldstone pion having a vanishing mass in that limit.
13509849
Stable operation of a 300-m laser interferometer with sufficient sensitivity to detect gravitational-wave events within our galaxy.
TAMA300, an interferometric gravitational-wave detector with 300-m baseline length, has been developed and operated with sufficient sensitivity to detect gravitational-wave events within our galaxy and sufficient stability for observations; the interferometer was operated for over 10 hours stably and continuously. With a strain-equivalent noise level of h approximately 5x10(-21)/sqrt[Hz], a signal-to-noise ratio of 30 is expected for gravitational waves generated by a coalescence of 1.4M-1.4M binary neutron stars at 10 kpc distance. We evaluated the stability of the detector sensitivity with a 2-week data-taking run, collecting 160 hours of data to be analyzed in the search for gravitational waves.
120819057
One Gluon Exchange Contributions to Electromagnetic Mass Differences
123768278
The Lowest (1/2+ and 0-) Hadron Masses and the Behavior of the Constituent Quarks
Masses of the lowest lying hadrons and the behavior of constituent quarks are discussed on the analysis of their electromagnetic properties, based on QCD. We find that light quarks (u and d) in the hadrons move with the velocity ::::O.Sc; s quark, with :$0.7c; c quark, with nearly 0.3c. Then we know that the confinement force, no matter what kind of confinement one prefers, does not mainly contribute to the hadron masses. It is also conjectured that Jv,-eJilu-d J;=;[v1,-,11[/Jc-sJ;=;Jv,-rJ/ lt-bl and m,:-::23 GeV on the assumption of the ex­ istence of the next layer. Masses of quarks, of which a hadron is built, are assumed arbitrarily to be from zero to infinity on the argument of various hadronic processes, but the constituent quark masses seem to be mu:-::330 and ms:-::510 (in units of MeV) in the inter­ mediate region at which the magnetic moments and the spectroscopy of hadrons are discussed.ll Can 7r have a mass of an order of one hundred MeV, when it is considered that it is a bound state of such quarks? How do the quarks behave in 7r or other hadrons? This note will con­ tribute to the analysis of the lowest lying hadron masses on the basis of the analysis of the electromagnetic properties by follow­ ing the previous discussions. 2>
18101517
Effective System for Simulating Dust Continuum Observations on Distributed Computing Resources
We present an effective system for simulating dust continuum observations by radiative transfer simulations. By using workflow management system RENKEI-WFT, we utilized distributed computing resources and automated a sequence of computational tasks required for radiative transfer modeling, namely, main radiative transfer simulations, pre-/post-processes, and data transfer between computing resources. Our system simultaneously executes a lot of radiative transfer simulations with different input parameters on distributed computing resources. This capability of our system enables us to conduct effective research by radiative transfer simulation. As a demonstration of our system, we simulated dust continuum observations of protoplanetary disk. We performed hydrodynamic simulation modeling photoevaporating protoplanetary disk irradiated by ultra violet radiation from nearby massive stars. Results of this hydrodynamic simulation were used as input data for radiative transfer simulations. Expected spectral energy distributions and intensity maps were obtained by our system.
11024901
Joint LIGO and TAMA300 search for gravitational waves from inspiralling neutron star binaries
We search for coincident gravitational wave signals from inspiralling neutron star binaries using LIGO and TAMA300 data taken during early 2003. Using a simple trigger exchange method, we perform an intercollaboration coincidence search during times when TAMA300 and only one of the LIGO sites were operational. We find no evidence of any gravitational wave signals. We place an observational upper limit on the rate of binary neutron star coalescence with component masses between 1 and 3M⊙ of 49 per year per Milky Way equivalent galaxy at a 90% confidence level. The methods developed during this search will find application in future network inspiral analyses.