56 research outputs found
A study of the quenched bc mass spectrum at beta=6.2
We present an analysis of the mass spectrum of heavy quarkonia with
non-degenerate quark masses. The heavier (bottom) valence quark is treated in a
non-relativistic fashion and the other (charm) is a relativistic Wilson-like
quark using the improved SW action. Such states provide and interesting probe
between the relativistic B meson states and the non-relativistic bottomonium
states.Comment: 4 pages LaTeX, 4 postscript figures. requires espcrc2.sty and
epsf.sty. To be published in the proceedings of Lattice 97, Edinburgh,
Scotlan
Hybrid Quarkonia with High Statistics from NRQCD
We have studied the O(mv^6) effects in NRQCD on the spectrum of heavy
quarkonia and compare our results for different lattices (quenched and
dynamical). We also report on an investigation into hybrid states within the
framework of NRQCD. This suggests that the lowest lying hybrid is around the
B^* \bar B threshold and 3 standard deviations above the B \bar B.Comment: 3 pages, LaTeX2e, 4 figures, uses styles [espcrc2, epsf], talk
presented at Lattice 9
NRQCD on an anisotropic lattice
We present preliminary results for the Upsilon spectrum on an anisotropic
lattice using the improved O(mv^6) NRQCD Hamiltonian. We find accurate results
can be obtained in moderate computer times and that they agree with earlier
results on an isotropic lattice.Comment: 3 pages, LATEX2e, talk presented at LATTICE '98 by R.R. Horgan, uses
styles[espcrc2,epsfig
Heavy-light decay constants from clover heavy quark action in QCD with two flavors of dynamical quarks
We present results on an analysis of the decay constants f_B and f_Bs with
two flavours of sea quark. The calculation has been carried out on 3 different
bare gauge couplings and 4 sea quark masses at each gauge coupling, with
m_pi/m_rho ranging from 0.8 to 0.6. We employ the Fermilab formalism to perform
calculations with heavy quarks whose mass is in the range of the b-quark. A
detailed comparison with a quenched calculation using the same action is made
to elucidate the effects due to the sea quarks.Comment: Contribution to Lattice 99 (Heavy Quarks). Latex file, uses
espcrc2.sty and epsf.sty. 3 pages, 3 encapsulated postscript figure
Quenched Light Hadron Spectrum with the Wilson Quark Action: Final Results from CP-PACS
We report the final results of the CP-PACS calculation for the quenched light
hadron spectrum with the Wilson quark action. Our data support the presence of
quenched chiral singularities, and this motivates us to use mass formulae based
on quenched chiral perturbation theory in order to extrapolate hadron masses to
the physical point. Hadron masses and decay constants in the continuum limit
show unambiguous systematic deviations from experiment. We also report the
results for light quark masses.Comment: LATTICE98(spectrum). The poster at Lattice98 can be obtained from
http://www.rccp.tsukuba.ac.jp/people/yoshie/Lat98.Poster
Heavy Quark Physics in Nf=2 QCD
We present a preliminary analysis of the heavy-heavy spectrum and heavy-light
decay constants in full QCD, using a tadpole-improved SW quark action and an
RG-improved gauge action on a 16^3 x 32 lattice with four sea quark masses
corresponding to m_pi/m_rho = 0.8, 0.75, 0.7, 0.6 and a^-1 = 1.3 GeV. We focus
particularly on the effect of sea quarks on these observables.Comment: 3 pages Latex, 3 eps figures. Uses espcrc2.sty and epsf.sty . To
appear in the Proceedings of Lattice 98 (Heavy Quarks
Upsilon Spectrum from NRQCD with Improved Action
We explore the effect of higher order operators in the non-relativistic
formulation of QCD (NRQCD). We calculated masses in the b \bar b spectrum using
quenched gauge configurations at beta = 6.0 and two different NRQCD actions
which have been corrected to order mv^4 and mv^6. The two-point functions are
calculated in a gauge invariant fashion. We find the general structure of the
spectrum to be the same in the two cases. Using the P - 3S1 splitting we
determine the inverse lattice spacings to be 2.44(4) GeV and 2.44(5) GeV for
the mv^4 and mv^6 actions, respectively. We do observe shifts in the spin
splittings. The hyperfine splitting is reduced by approximately 4 MeV, while
the fine splitting is down by up to 10 MeV, albeit with large statistical
errors.Comment: 11 pages, LaTeX2e , 4 figures, uses styles [11pt, a4wide, epsf]. A
minor typo in figure 2 has been correcte
Serum antibodies in first-degree relatives of patients with IBD: A marker of disease susceptibility? A follow-up pilot-study after 7 years
Introduction: Various disease-specific serum antibodies were described in patients with inflammatory bowel disease and their yet healthy first-degree relatives. In the latter, serum antibodies are commonly regarded as potential markers of disease susceptibility. The present long-term follow-up study evaluated the fate of antibody-positive first-degree relatives. Patients and Methods: 25 patients with Crohn's disease, 19 patients with ulcerative colitis and 102 first-degree relatives in whom presence of ASCA, pANCA, pancreatic- and goblet-cell antibodies had been assessed were enrolled. The number of incident cases with inflammatory bowel disease was compared between antibody-positive and antibody-negative first-degree relatives 7 years after storage of serum samples. Results: 34 of 102 (33%) first-degree relatives were positive for at least one of the studied serum antibodies. In the group of first-degree relatives, one case of Crohn's disease and one case of ulcerative colitis were diagnosed during the follow-up period. However, both relatives did not display any of the investigated serum antibodies (p = 1). Discussion: The findings of our pilot study argue against a role of serum antibodies as a marker of disease susceptibility in first-degree relatives of patients with inflammatory bowel disease. However, these data have to await confirmation in larger ideally prospective multicenter studies before definite conclusions can be drawn
Serum antibodies in first-degree relatives of patients with IBD: A marker of disease susceptibility? A follow-up pilot-study after 7 years
Introduction: Various disease-specific serum antibodies were described in patients with inflammatory bowel disease and their yet healthy first-degree relatives. In the latter, serum antibodies are commonly regarded as potential markers of disease susceptibility. The present long-term follow-up study evaluated the fate of antibody-positive first-degree relatives. Patients and Methods: 25 patients with Crohn's disease, 19 patients with ulcerative colitis and 102 first-degree relatives in whom presence of ASCA, pANCA, pancreatic- and goblet-cell antibodies had been assessed were enrolled. The number of incident cases with inflammatory bowel disease was compared between antibody-positive and antibody-negative first-degree relatives 7 years after storage of serum samples. Results: 34 of 102 (33%) first-degree relatives were positive for at least one of the studied serum antibodies. In the group of first-degree relatives, one case of Crohn's disease and one case of ulcerative colitis were diagnosed during the follow-up period. However, both relatives did not display any of the investigated serum antibodies (p = 1). Discussion: The findings of our pilot study argue against a role of serum antibodies as a marker of disease susceptibility in first-degree relatives of patients with inflammatory bowel disease. However, these data have to await confirmation in larger ideally prospective multicenter studies before definite conclusions can be drawn
Light hadron spectrum and quark masses in QCD with two flavors of dynamical quarks
We present updated results of the CP-PACS calculation of the light hadron
spectrum in full QCD. Simulations are made with an RG-improved
gauge action and a tadpole-improved clover quark action for sea quark masses
corresponding to --0.6 and the lattice
spacing --0.09 fm. A comparison of the full QCD spectrum with new
quenched results, obtained with the same improved action, shows clearly the
existence of sea quark effects in vector meson masses. Results for light quark
masses in QCD are also presented.Comment: Latex 3 pages, 6 PostScript figures, Talk presented at LATTICE99(QCD
Spectrum and Quark Masses
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