1,691 research outputs found
TAU-PAIR PRODUCTION VIA PHOTON-PHOTON COLLISIONS AT LEP
We point out that the cross-section for the process at LEP is large enough to allow for a study of the anomalous
electromagnetic couplings of the lepton. We show that the present bounds
on the magnetic dipole moment can be improved and that competitive bounds can
be obtained for the electric dipole moment using the data taken from 1992 to
1994. Finally, we briefly discuss the improvements that can be obtained at LEP
II.Comment: 9 pages, latex, 2 figure
Evolution of Coronal Magnetic Field Parameters during X5.4 Solar Flare
The coronal magnetic field over NOAA Active Region 11,429 during a X5.4 solar flare on 7 March 2012 is modeled using optimization based Non-Linear Force-Free Field extrapolation. Specifically, 3D magnetic fields were modeled for 11 timesteps using the 12-min cadence Solar Dynamics Observatory (SDO) Helioseismic and Magnetic Imager photospheric vector magnetic field data, spanning a time period of 1 hour before through 1 hour after the start of the flare. Using the modeled coronal magnetic field data, seven different magnetic field parameters were calculated for 3 separate regions: areas with surface |Bz|â„ 300 G, areas of flare brightening seen in SDO Atmospheric Imaging Assembly imagery, and areas with surface |B| â„ 1000 G and high twist. Time series of the magnetic field parameters were analyzed to investigate the evolution of the coronal field during the solar flare event and discern pre-eruptive signatures. The data shows that areas with |B| â„ 1000 G and |Tw|â„ 1.5 align well with areas of initial flare brightening during the pre-flare phase and at the beginning of the eruptive phase of the flare, suggesting that measurements of the photospheric magnetic field strength and twist can be used to predict the flare location within an active region if triggered. Additionally, the evolution of seven investigated magnetic field parameters indicated a destabilizing magnetic field structure that could likely erupt
A relativistic chiral quark model for pseudoscalar emission from heavy mesons
The amplitudes for one-pion mediated transitions between heavy meson excited
states are obtained in the framework of the relativistic chiral quark model.
The effective coupling constants to pions and the decay widths of excited heavy
mesons with l<=2 for non-radially excited, and the l=0 radially excited mesons
are presented for both charmed and beauty mesons. We also discuss the allowed
decays of strange excited heavy mesons by emission of a K-meson.Comment: 20 pages, revte
Forward-Backward Asymmetries in Hadronically Produced Lepton Pairs
It has now become possible to observe appreciable numbers of hadronically
produced lepton pairs in mass ranges where the contributions of the photon and
are comparable. Consequently, in the reaction , substantial forward-backward asymmetries can be seen. These
asymmetries provide a test of the electroweak theory in a new regime of
energies, and can serve as diagnostics for any new neutral vector bosons
coupling both to quarks and to charged lepton pairs.Comment: 11 pages, latex, 4 uuencoded figures sent separately, Fig. 2 revise
The lepton flavor violating decays in the simplest little Higgs model
In the simplest little Higgs model the new flavor-changing interactions
between heavy neutrinos and the Standard Model leptons can generate
contributions to some lepton flavor violating decays of -boson at one-loop
level, such as , , and . We examine the decay modes, and find that the branching
ratios can reach for the three decays, which should be accessible at
the Giga option of the ILC.Comment: 12 pages, 9 figure
Inclusive B-Meson Production in e^+ e^- and p p-bar Collisions
We provide nonperturbative fragmentation functions for B mesons, both at
leading and next-to-leading order in the MS-bar factorization scheme with five
massless quark flavors. They are determined by fitting the fractional energy
distribution of B mesons inclusively produced in e^+ e^- annihilation at CERN
LEP1. Theoretical predictions for the inclusive production of B mesons with
high transverse momenta in p p-bar scattering obtained with these fragmentation
functions nicely agree, both in shape and normalization, with data recently
taken at the Fermilab Tevatron.Comment: 20 pages (Latex), 6 figures (Postscript
Basketball game-related statistics that discriminate between teams season-long success
The aim of the present study was to identify the game-related statistics that discriminate between season-long successful and unsuccessful basketball teams participating in the Spanish Basketball League (LEB1). The sample included all 145 average records per season from the 870 games played between the 2000-2001 and the 2005-2006 regular seasons. The following game-related statistics were gathered from the official box scores of the Spanish Basketball Federation: 2- and 3-point field-goal attempts (both successful and unsuccessful), free-throws (both successful and unsuccessful), defensive and offensive rebounds, assists, steals, turnovers, blocks (both made and received), and fouls (both committed and received). To control for season variability, all results were normalized to minutes played each season and then converted to z-scores. The results allowed discrimination between best and worst teams' performances through the following game-related statistics: assists (SC=0.47), steals (SC=0.34), and blocks (SC=0.30). The function obtained correctly classified 82.4% of the cases. In conclusion, season-long performance may be supported by players' and teams' passing skills and defensive preparation
Extremely High Energy Neutrinos, Neutrino Hot Dark Matter, and the Highest Energy Cosmic Rays
Extremely high energy (up to 10**(22) eV) cosmic neutrino beams initiate high
energy particle cascades in the background of relic neutrinos from the Big
Bang. We perform numerical calculations to show that such cascades could
contribute more than 10% to the observed cosmic ray flux above 10**(19) eV if
neutrinos have masses in the electron volt range. The required intensity of
primary neutrinos could be consistent with astrophysical models for their
production if the maximum neutrino energy reaches to 10**(22) eV and the
massive neutrino dark matter is locally clustered. Future observations of ultra
high energy cosmic rays will lead to an indirect but practical search for
neutrino dark matter.Comment: 4 latex pages, 3 postscript figures included, uses revtex.sty and
psfig.sty. Submitted to Physical Review Letter
Four-jet angular distributions and color charge measurements: leading order versus next-to-leading order
We present the next-to-leading order perturbative QCD prediction to the
four-jet angular distributions used by experimental collaborations at LEP for
measuring the QCD color charge factors. We compare our results to ALEPH data
corrected to parton level. We perform a leading order ``measurement'' of the
QCD color factor ratios by fitting the leading order perturbative predictions
to the next-to-leading order result. Our result shows that in an experimental
analysis for measuring the color charge factors the use of the O()
QCD predictions instead of the O() results may shift the center of
the fit by a relative factor of 1+2\as in the direction.Comment: 14 pages, 10 tables, 5 figures, revtex, eps style
Effects of R-parity violation on CP asymmetries in decay
We have studied new CP violating effects in decay mode,
that can arise in Minimal Supersymmetric Standard Model with R-parity
violation. We have estimated how much R-parity violation modifies the Standard
Model predictions for CP asymmetries within the present bounds. We found that
in the R-parity violating model, the rate asymmetry () is suppressed
(about 10 times) and the asymmetry parameter is enhanced
(approximately times) with respect to the SM predictions.Comment: Latex, 8 page
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