Observation of a cross-section enhancement near mass threshold in $e^{+}e^{-}\rightarrow\Lambda\bar{\Lambda}$ - INSPIRE

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Observation of a cross-section enhancement near mass threshold in $e^{+}e^{-}\rightarrow\Lambda\bar{\Lambda}$

BESIII

Collaboration

Sep 29, 2017

9 pages

Published in:

Phys.Rev.D 97 (2018) 3, 032013

Published: Feb 28, 2018

e-Print:

1709.10236 [hep-ex]

DOI:

10.1103/PhysRevD.97.032013

Experiments:

BEPC-BES-III

View in:

reference search108 citations

Citations per year

Abstract: (APS)

The process e+e-→ΛΛ¯ is studied using data samples at s=2.2324, 2.400, 2.800 and 3.080 GeV collected with the BESIII detector operating at the BEPCII collider. The Born cross section is measured at s=2.2324 GeV, which is 1.0 MeV above the ΛΛ¯ mass threshold, to be 305±45-36+66 pb, where the first uncertainty is statistical and the second systematic. The cross section near threshold is larger than that expected from theory, which predicts the cross section to vanish at threshold. The Born cross sections at s=2.400, 2.800 and 3.080 GeV are measured and found to be consistent with previous experimental results, but with improved precision. Finally, the corresponding effective electromagnetic form factors of Λ are deduced.

electron positron: annihilation
electron positron: colliding beams
Lambda: pair production
mass: threshold
mass spectrum: (Lambda Antilambda)
cross section: enhancement
channel cross section: measured
Lambda: form factor
form factor: electromagnetic
Born approximation

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Figures(5)

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