10 research outputs found
A model of decay
We suggest a parameterization of the matrix element for decay using kinematic variables convenient for experimental
analysis. The contributions of intermediate - and -states up
to spin 3 have been taken into account. The angular distributions for each
discussed hypothesis have been obtained and analysed using Monte-Carlo
simulation.Comment: 24 pages, 9 figures, 1 table; V2: text in some places improved and
acknowledgments adde
Quark-mass dependence in decays
We study the quark-mass dependence of decays, based on a
dispersion-theoretical framework. We rely on the quark-mass-dependent
scattering phase shift for the pion-pion -wave extracted from unitarized
chiral perturbation theory. The dispersive representation then takes into
account the final-state rescattering among all three pions. The described
formalism may be used as an extrapolation tool for lattice QCD calculations of
three-pion decays, for which can serve as a paradigm case.Comment: 12 pages, 8 figures; v2: added two references, version published in
EPJ
The MSSM confronts the precision electroweak data and the muon g-2
We update the electroweak study of the predictions of the Minimal
Supersymmetric Standard Model (MSSM) including the recent results on the muon
anomalous magnetic moment, the weak boson masses, and the final precision data
on the Z boson parameters from LEP and SLC. We find that the region of the
parameter space where the slepton masses are a few hundred GeV is favored from
the muon g-2 for \tan\beta \ltsim 10, whereas for \tan\beta \simeq 50 heavier
slepton mass up to \sim 1000 GeV can account for the reported 3.2 \sigma
difference between its experimental value and the Standard Model (SM)
prediction. As for the electroweak measurements, the SM gives a good
description, and the sfermions lighter than 200 GeV tend to make the fit worse.
We find, however, that sleptons as light as 100 to 200 GeV are favored also
from the electroweak data, if we leave out the jet asymmetry data that do not
agree with the leptonic asymmetry data. We extend the survey of the preferred
MSSM parameters by including the constraints from the b \to s \gamma
transition, and find favorable scenarios in the minimal supergravity, gauge-,
and mirage-mediation models of supersymmetry breaking.Comment: 40 pages, 12 figures. v2: minor changes, references added, version to
appear in JHE
Measurement of the <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mi>e</mml:mi><mml:mo>+</mml:mo></mml:msup><mml:msup><mml:mi>e</mml:mi><mml:mo>â</mml:mo></mml:msup><mml:mo stretchy="false">â</mml:mo><mml:msup><mml:mi>Ï</mml:mi><mml:mo>+</mml:mo></mml:msup><mml:msup><mml:mi>Ï</mml:mi><mml:mo>â</mml:mo></mml:msup></mml:math> cross section from threshold to 1.2Â GeV with the CMD-3 detector
The cross section of the process e+eââÏ+Ïâ has been measured in the center of mass energy range from 0.32 to 1.2 GeV with the CMD-3 detector at the electron-positron collider VEPP-2000. The measurement is based on a full dataset collected below 1 GeV during three data taking seasons, corresponding to an integrated luminosity of about 62ââpbâ1. In the dominant Ï-resonance region, a systematic uncertainty of 0.7% has been reached. At energies around Ï-resonance the Ï+Ïâ production cross section was measured for the first time with high beam energy resolution. The forward-backward charge asymmetry in the Ï+Ïâ production has also been measured. It shows a strong deviation from the theoretical prediction based on the conventional scalar quantum electrodynamics framework, and it is in good agreement with the generalized vector-meson-dominance and dispersive-based predictions. The impact of the presented results on the evaluation of the hadronic contribution to the anomalous magnetic moment of muon is discussed.
Published by the American Physical Society
2024
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Measurement of the Pion Form Factor with CMD-3 Detector and Its Implication to the Hadronic Contribution to Muon (g-2).
The cross section of the process e^{+}e^{-}âÏ^{+}Ï^{-} has been measured in the center-of-mass energy range from 0.32 to 1.2 GeV with the CMD-3 detector at the electron-positron collider VEPP-2000. The measurement is based on an integrated luminosity of about 88ââpb^{-1}, of which 62ââpb^{-1} represent a complete dataset collected by CMD-3 at center-of-mass energies below 1 GeV. In the dominant region near the Ï resonance a systematic uncertainty of 0.7% was achieved. The implications of the presented results for the evaluation of the hadronic contribution to the anomalous magnetic moment of the muon are discussed