1,036 research outputs found
On the T-Odd Quark Fragmentation Function and on Transversal Handedness
The first probe of the correlation of the T-odd one-particle fragmentation
function responsible for the left--right asymmetry of fragmentation of a
transversely polarized quark is done by using the 1991-95 DELPHI data for -jet decay. Integrated over the fraction of longitudinal and transversal
momenta, this correlation is of 1.5% order, which means order of 13% for the
analyzing power.
A rather large () handedness transversal to the production plane
was observed in the diffractive production of () triples from
nuclei by the --beam. It was shown that the phenomenon has a
clear dynamic origin and resembles the single spin asymmetry behavior. All this
makes us hope to use this effects in polarized DIS experiments for transversity
measurement.Comment: 10 pp, 5 epsfig, Latex 2e, szjp.cls, epsfig.sty, wrapfig.sty
included. Talk in "Spin and Symmetry - Praha98". To be published in
Czechoslovak Journal of Physics, Supp
Study of correlation of production and decay planes in diffractive dissociation process on nuclei
A large correlation of production and decay planes of
(\pi^-\pi^+\pi^-)-system in dissociation of -beam 40 GeV/c on nuclear
targets was observed. The dependence of the correlation on atomic number,
Feynmann variable and transversal momentum as well as on invariant mass of the
pion triple and neutral pion pair were investigated. It was shown that the
phenomenon has a clear dynamic origin and resembles the single spin asymmetry
behavior.Comment: 8 pages, latex epsfig.sty, 5 eps figures. Submitted to Yad. Fiz
Search for axions in streaming dark matter
A new search strategy for the detection of the elusive dark matter (DM) axion
is proposed. The idea is based on streaming DM axions, whose flux might get
temporally enormously enhanced due to gravitational lensing. This can happen if
the Sun or some planet (including the Moon) is found along the direction of a
DM stream propagating towards the Earth location. The experimental requirements
to the axion haloscope are a wide-band performance combined with a fast axion
rest mass scanning mode, which are feasible. Once both conditions have been
implemented in a haloscope, the axion search can continue parasitically almost
as before. Interestingly, some new DM axion detectors are operating wide-band
by default. In order not to miss the actually unpredictable timing of a
potential short duration signal, a network of co-ordinated axion antennae is
required, preferentially distributed world-wide. The reasoning presented here
for the axions applies to some degree also to any other DM candidates like the
WIMPs.Comment: 5 page
Performance of the Scintillator System Prototype of the NUCLEON Space Experiment
Abstract The NUCLEON space experiment has been proposed to perform direct measurements of CR energy spectrum and composition up to E ∼ 10 15 eV. The NUCLEON detector consists of layers of different detectors: scintillator detectors with WLS fibers and silicon pad and microstrip ones. The results of beam and space qualification tests of the scintillator detectors are presented
Measurement of the Ratio Gamma(KL -> pi+ pi-)/Gamma(KL -> pi e nu) and Extraction of the CP Violation Parameter |eta+-|
We present a measurement of the ratio of the decay rates Gamma(KL -> pi+
pi-)/Gamma(KL -> pi e nu), denoted as Gamma(K2pi)/Gamma(Ke3). The analysis is
based on data taken during a dedicated run in 1999 by the NA48 experiment at
the CERN SPS. Using a sample of 47000 K2pi and five million Ke3 decays, we find
Gamma(K2pi)/Gamma(Ke3) = (4.835 +- 0.022(stat) +- 0.016(syst)) x 10^-3. From
this we derive the branching ratio of the CP violating decay KL -> pi+ pi- and
the CP violation parameter |eta+-|. Excluding the CP conserving direct photon
emission component KL -> pi+ pi- gamma, we obtain the results BR(KL -> pi+ pi-)
= (1.941 +- 0.019) x 10^-3 and |eta+-| = (2.223 +- 0.012) x 10^-3.Comment: 20 pages, 7 figures, accepted by Phys. Lett.
Measurement of the branching ratio of the decay KL -> pi e nu and extraction of the CKM parameter |Vus|
We present a new measurement of the branching ratio R of the decay KL -> pi e
nu (Ke3), relative to all charged KL decays with two tracks, based on data
taken with the NA48 detector at the CERN SPS. We measure R = 0.4978 +- 0.0035.
From this we derive the Ke3 branching fraction and the weak coupling
parameter |Vus| in the CKM matrix. We obtain |Vus|f+(0) = 0.2146 +- 0.0016,
where f+(0) is the vector form factor in the Ke3 decay.Comment: 18 pages, 8 figures. accepted by Phys Lett.
A new measurement of direct CP violation in two pion decays of the neutral kaon
The NA48 experiment at CERN has performed a new measurement of direct CP
violation, based on data taken in 1997 by simultaneously collecting K_L and K_S
decays into pi0pi0 and pi+pi-. The result for the CP violating parameter
Re(epsilon'/epsilon) is (18.5 +/- 4.5(stat)} +/- 5.8 (syst))x10^{-4}.Comment: 18 pages, 6 figure
First Measurement of Chiral Dynamics in \pi^- \gamma -> \pi^- \pi^- \pi^+
The COMPASS collaboration at CERN has investigated the \pi^- \gamma -> \pi^-
\pi^- \pi^+ reaction at center-of-momentum energy below five pion masses,
sqrt(s) < 5 m(\pi), embedded in the Primakoff reaction of 190 GeV pions
impinging on a lead target. Exchange of quasi-real photons is selected by
isolating the sharp Coulomb peak observed at smallest momentum transfers, t' <
0.001 (GeV/c)^2. Using partial-wave analysis techniques, the scattering
intensity of Coulomb production described in terms of chiral dynamics and its
dependence on the 3\pi-invariant mass m(3\pi) = sqrt(s) were extracted. The
absolute cross section was determined in seven bins of with an
overall precision of 20%. At leading order, the result is found to be in good
agreement with the prediction of chiral perturbation theory over the whole
energy range investigated.Comment: 10 pages, 5 figure
First Measurement of the Transverse Spin Asymmetries of the Deuteron in Semi-Inclusive Deep Inelastic Scattering
First measurements of the Collins and Sivers asymmetries of charged hadrons
produced in deep-inelastic scattering of muons on a transversely polarized
6-LiD target are presented. The data were taken in 2002 with the COMPASS
spectrometer using the muon beam of the CERN SPS at 160 GeV/c. The Collins
asymmetry turns out to be compatible with zero, as does the measured Sivers
asymmetry within the present statistical errors.Comment: 6 pages, 2 figure
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