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.
14184377
BROWN-RHO SCALING IN THE STRONG COUPLING LATTICE QCD
We examine the Brown-Rho scaling for meson masses in the strong coupling limit of lattice QCD with one species of staggered fermion. Analytical expression of meson masses is derived at finite temperature and chemical potential. We find that meson masses are approximately proportional to the equilibrium value of the chiral condensate, which evolves as a function of temperature and chemical potential.
118756026
Phases of many flavors QCD : Lattice results
This note is based on our recent results on QCD with varying number of flavors of fundamental fermions. Topics include unusual, strong dynamics in the preconformal, confining phase, the physics of the conformal window and the role of ab-initio lattice simulations in establishing our current knowledge of the phases of many flavor QCD.
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.
119461969
Phase diagram at finite temperature and quark density in the strong coupling region of lattice QCD for colour SU(3)
We study the phase diagram of quark matter at finite temperature (T) and chemical potential (μ) in the strong coupling region of lattice QCD for colour SU(3). Baryon has effects to extend the hadron phase to a larger μ direction relative to T c at low temperatures in the strong coupling limit. With the l/g 2 corrections, T c is found to decrease rapidly as g decreases, and the shape of the phase diagram becomes closer to that expected in the real world.
119164995
Strong Coupling Limit/Region of Lattice QCD
We study the phase diagram of quark matter and nuclear properties based on the strong coupling expansion of lattice QCD. Both of baryon and finite coupling correction are found to have effects to extend the hadron phase to a larger μ direction relative to Tc. In a chiral RMF model with logarithmic sigma potential derived in the strong coupling limit of lattice QCD, we can avoid the chiral collapse and normal and hypernuclei properties are well described.
120461364
Electromagnetic Mass Differences of Charmed Particles
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.
122795239
Electromagnetic Mass Differences of Lowest Lying Hadrons and Behavior of Quarks in Hadrons
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>
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.