10,263 research outputs found
Scaling test of quenched Wilson twisted mass QCD at maximal twist
We present the results of an extended scaling test of quenched Wilson twisted
mass QCD. We fix the twist angle by using two definitions of the critical mass,
the first obtained by requiring the vanishing of the pseudoscalar meson mass
m_PS for standard Wilson fermions and the second by requiring restoration of
parity at non-zero value of the twisted mass mu and subsequently extrapolating
to mu=0. Depending on the choice of the critical mass we simulate at values of
beta in [5.7,6.45], for a range of pseudoscalar meson masses 250 MeV < m_PS < 1
GeV and we perform the continuum limit for the pseudoscalar meson decay
constant f_PS and various hadron masses (vector meson m_V, baryon octet m_oct
and baryon decuplet m_dec) at fixed value of r_0 m_PS. For both definitions of
the critical mass, lattice artifacts are consistent with O(a) improvement.
However, with the second definition, large O(a^2) discretization errors present
at small quark mass with the first definition are strongly suppressed. The
results in the continuum limit are in very good agreement with those from the
Alpha and CP-PACS Collaborations.Comment: 6 pages, Talk presented at Lattice 2005, Dublin, 25-30 July 200
Bond Strength Tests Between Silicon Wafers and Duran Tubes (Fusion Bonded Fluidic Interconnects)
The fusion bond strength of glass tubes with standard silicon wafers is presented. Experiments with plain silicon wafers and those coated with silicon oxide and silicon nitride are presented. Results obtained are discussed in terms of homogeneity and strength of fusion bond. High pressure testing shows that the bond strength is large enough for most applications of fluidic interconnects. The bond strength for 525 /spl mu/m thick silicon with glass tubes having outer diameter of 6 mm and with wall thickness 2 mm, is more than 60 bars after annealing at a temperature of 800/spl deg/C
Phonon-assisted tunneling in the quantum regime of Mn12-ac
Longitudinal or transverse magnetic fields applied on a crystal of Mn12-ac
allows to observe independent tunnel transitions between m=-S+p and m=S-n-p
(n=6-10, p=0-2 in longitudinal field and n=p=0 in transverse field). We observe
a smooth transition (in longitudinal) from coherent ground-state to thermally
activated tunneling. Furthermore two ground-state relaxation regimes showing a
crossover between quantum spin relaxation far from equilibrium and near
equilibrium, when the environment destroys multimolecule correlations. Finally,
we stress that the complete Hamiltonian of Mn12 should contain odd spin
operators of low order
Interactions that matter:Understanding residents' professional growth through workplace relationships
3-point functions from twisted mass lattice QCD at small quark masses
We show at the example of the matrix element between pion states of a
twist-2, non-singlet operator that Wilson twisted mass fermions allow to
compute this phenomenologically relevant quantitiy at small pseudo scalar
masses of O(270 MeV). In the quenched approximation, we investigate the scaling
behaviour of this observable that is derived from a 3-point function by
applying two definitions of the critical mass and find a scaling compatible
with the expected O(a^2) behaviour in both cases. A combined continuum
extrapolations allows to obtain reliable results at small pion masses, which
previously could not be explored by lattice QCD simulations.Comment: 6 pages, 2 figures, talk presented at Lattice 200
3D-melting features of the irreversibility line in overdoped BiSrCuO at ultra-low temperature and high magnetic field
We have measured the irreversible magnetization of an overdoped
BiSrCuO single crystal up to B=28 T and down to T=60 mK, and
extracted the irreversibility line : the data can be
interpreted in the whole temperature range as a 3D-anisotropic vortex lattice
melting line with Lindemann number . We also briefly discuss
the applicability of alternative models such as 2D- and quantum melting, and
the connection with magnetoresistance experiments.Comment: M2S-HTSC-VI Conference paper (2 pages, 1 figure), using Elsevier
style espcrc2.st
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