First direct measurement of the absolute branching fraction of Sigma(+) -> Lambda e(+)upsilon(e)

For complete list of authors see http://dx.doi.org/10.1103/PhysRevD.107.072010
The first direct measurement of the absolute branching fraction of Sigma(+) -> Lambda e(+)nu(e) is reported based on an e(+) e(-) annihilation sample of (10087 +/- 44) x 10(6) J/psi events collected with the BESIII detector at root s = 3.097 GeV. The branching fraction is determined to be B(Sigma(+)-> Lambda e(+)nu(e))=2.93 +/- 0.74 (stat) +/- 0.13(syst)] x 10(-5), which is the most precise measurement obtained in a single experiment to date and also the first result obtained at a collider experiment. Combining this result with the world average of B(Sigma(-)-> Lambda e(-) (nu) over bar (e). and the lifetimes of Sigma(+/-), the ratio, Gamma (Sigma(-) ->Lambda e(-) (nu) over bar (e) /Sigma(+) -> Lambda e(+) (nu) over bar (e), is determined to be 1.06 +/- 0.28, which is within 1.8 standard deviations of the value expected in the absence of second-class currents.

Adlarson, PatrikUppsala universitet,Kärnfysik(Swepub:uu)patad399 (author)
Johansson, TordUppsala universitet,Kärnfysik(Swepub:uu)tordjoha (author)
Kupsc, AndrzejUppsala universitet,Kärnfysik,Natl Ctr Nucl Res, PL-02093 Warsaw, Poland.(Swepub:uu)andrkups (author)
Schönning, Karin,1978-Uppsala universitet,Kärnfysik(Swepub:uu)kasch734 (author)
Thorén, ViktorUppsala universitet,Kärnfysik(Swepub:uu)vikth925 (author)
Wolke, MagnusUppsala universitet,Kärnfysik(Swepub:uu)mawol031 (author)
Zu, J.State Key Lab Particle Detect & Elect, Hefei 230026, Peoples R China;Univ Sci & Technol China, Hefei 230026, Peoples R China (author)
Inst High Energy Phys, Beijing 100049, Peoples R ChinaKärnfysik (creator_code:org_t)

By the author/editor: Ablikim, M.; Adlarson, Patrik; Johansson, Tord; Kupsc, Andrzej; Schönning, Karin ...; Thorén, Viktor; show more...; Wolke, Magnus; Zu, J.; show less...

About the subject

NATURAL SCIENCES: NATURAL SCIENCES; and Physical Science ...; and Subatomic Physic ...

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