1,145 research outputs found
Muonium hyperfine structure and hadronic effects
A new result for the hadronic vacuum polarization correction to the muonium
hyperfine splitting (HFS) is presented:
Delta nu(had - vp) = (0.233 +- 0.003) kHz.
Compared with previous calculations, the accuracy is improved by using the
latest data on e+e- -> hadrons. The status of the QED prediction for HFS is
discussed
Influence of Bottom Quark Jet Quenching on Single Electron Tomography of Au+Au
High transverse momentum single (non-photonic) electrons are shown to be
sensitive to the stopping power of both bottom, b, and charm, c, quarks in AA
collisions. We apply the DGLV theory of radiative energy loss to predict c and
b quark jet quenching and compare the FONLL and PYTHIA heavy flavor
fragmentation and decay schemes. We show that single electrons in the p_T=5-10
GeV range are dominated by the decay of b quarks rather than the more strongly
quenched c quarks in Au+Au collisions at sqrt{s}=200 AGeV. The {smaller} b
quark energy loss, even for extreme opacities with gluon rapidity densities up
to 3500, is predicted to limit the nuclear modification factor, R_{AA}, of
single electrons to the range R_{AA} ~ 0.5-0.6, in contrast to previous
predictions of R_{AA} ~ 0.2-0.3 based on taking only c quark jet fragmentation
into account.Comment: 6 pages, 6 eps figure
Lifespan theorem for constrained surface diffusion flows
We consider closed immersed hypersurfaces in and evolving by
a class of constrained surface diffusion flows. Our result, similar to earlier
results for the Willmore flow, gives both a positive lower bound on the time
for which a smooth solution exists, and a small upper bound on a power of the
total curvature during this time. By phrasing the theorem in terms of the
concentration of curvature in the initial surface, our result holds for very
general initial data and has applications to further development in asymptotic
analysis for these flows.Comment: 29 pages. arXiv admin note: substantial text overlap with
arXiv:1201.657
Search for CP violation in tau -> K^0_S pi nu_tau decays at Belle
We report on a search for CP violation in tau -> K^0_S pi nu_tau decays using
a data sample of 699 fb^{-1} collected in the Belle experiment at the KEKB
electron-positron asymmetric-energy collider. The CP asymmetry is measured in
four bins of the invariant mass of the K^0_S pi system and found to be
compatible with zero with a precision of O(10^{-3}) in each mass bin. Limits
for the CP violation parameter Im(eta_S) are given at a 90 % confidence level.
These limits are |Im(eta_S)|<0.026 or better, depending on the parameterization
used to describe the hadronic form factors and improve upon previous limits by
one order of magnitude
Search for leptonic decays of D0 mesons
We search for the flavor-changing neutral current decays D0\to mu+mu- and
D0\to e+e-, and for the lepton-flavor violating decays D0\to e\pm mu\mp using
660 fb^-1 of data collected with the Belle detector at the KEKB
asymmetric-energy e+e- collider. We find no evidence for any of these decays.
We obtain significantly improved upper limits on the branching fractions:
B(D0\to mu+mu-)<1.4x10-7, B(D0\to e+e-)<7.9x10-8, and B(D0\to e+mu-)+B(D0\to
mu+e-)<2.6x10-7 at 90% confidence level.Comment: 6 pages, 3 figure
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