1,992 research outputs found
Longitudinal muon spin relaxation in high purity aluminum and silver
The time dependence of muon spin relaxation has been measured in high purity
aluminum and silver samples in a longitudinal 2 T magnetic field at room
temperature, using time-differential \musr. For times greater than 10 ns, the
shape fits well to a single exponential with relaxation rates of
\lambda_{\textrm{Al}} = 1.3 \pm 0.2\,(\textrm{stat.}) \pm
0.3\,(\textrm{syst.})\,\pms and \lambda_{\textrm{Ag}} = 1.0 \pm
0.2\,(\textrm{stat.}) \pm 0.2\,(\textrm{syst.})\,\pms
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Report from the hyperon physics subgroup
A number of topics were considered in the Hyperon Group. As the time was reasonably short, and the group was not large, the list of topics is by no means exhaustive. The topics discussed should rather be considered a sampling of a much more extensive list of topics that might have been discussed. This report will thus consist of some brief remarks relevant to the topics discussed, and a few concluding remarks. The interested reader is referred to the reference for appropriate details.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87609/2/160_1.pd
A search for two body muon decay signals
Lepton family number violation is tested by searching for
decays among the 5.8 positive muon decay events analyzed by the
TWIST collaboration. Limits are set on the production of both massless and
massive bosons. The large angular acceptance of this experiment allows
limits to be placed on anisotropic decays, which can arise
from interactions violating both lepton flavor and parity conservation.
Branching ratio limits of order are obtained for bosons with masses
of 13 - 80 MeV/c and with different decay asymmetries. For bosons with
masses less than 13 MeV/c the asymmetry dependence is much stronger and
the 90% limit on the branching ratio varies up to . This is
the first study that explicitly evaluates the limits for anisotropic two body
muon decays.Comment: 7 pages, 5 figures, 2 tables, accepted by PR
Charge dependent azimuthal correlations in Pb--Pb collisions at TeV
Separation of charges along the extreme magnetic field created in non-central
relativistic heavy--ion collisions is predicted to be a signature of local
parity violation in strong interactions. We report on results for charge
dependent two particle azimuthal correlations with respect to the reaction
plane for Pb--Pb collisions at TeV recorded in 2010 with
ALICE at the LHC. The results are compared with measurements at RHIC energies
and against currently available model predictions for LHC. Systematic studies
of possible background effects including comparison with conventional
(parity-even) correlations simulated with Monte Carlo event generators of
heavy--ion collisions are also presented.Comment: Published in the proceedings of "Quark Matter 2011", Annecy-Franc
Baryon stopping and strange baryon/antibaryon production at SPS energies
The amount of proton stopping in central Pb+Pb collisions from 20-160 AGeV as
well as hyperon and antihyperon rapidity distributions are calculated within
the UrQMD model in comparison to experimental data at 40, 80 and 160 AGeV taken
recently from the NA49 collaboration. Furthermore, the amount of baryon
stopping at 160 AGeV for Pb+Pb collisions is studied as a function of
centrality in comparison to the NA49 data. We find that the strange baryon
yield is reasonably described for central collisions, however, the rapidity
distributions are somewhat more narrow than the data. Moreover, the
experimental antihyperon rapidity distributions at 40, 80 and 160 AGeV are
underestimated by up to factors of 3 - depending on the annihilation cross
section employed - which might be addressed to missing multi-meson fusion
channels in the UrQMD model.Comment: 18 pages, including 7 eps figures, to be published in Phys. Rev.
Measurement of the Muon Decay Parameter delta
The muon decay parameter delta has been measured by the TWIST collaboration.
We find delta = 0.74964 +- 0.00066(stat.) +- 0.00112(syst.), consistent with
the Standard Model value of 3/4. This result implies that the product Pmuxi of
the muon polarization in pion decay, Pmu, and the muon decay parameter xi falls
within the 90% confidence interval 0.9960 < Pmuxi < xi < 1.0040. It also has
implications for left-right-symmetric and other extensions of the Standard
Model.Comment: Extended to 5 pages. Referee's comments answere
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