Flavour Changing Neutral Current Decays of Heavy Baryons: The Case $Λ_b \to Λγ$

Abstract

We investigate the rare decay $Λ_b \to Λγ$ which receives both short and long distance contributions. We estimate the long distance contributions and find them very small. The form factors are obtained from $Λ_c \to Λ\ell \barν_\ell$ using heavy quark symmetry and a pole model. The short distance piece opens a window to new physics and we discuss the sensitivity of $Λ_b \to Λγ$ to such effects.

Latex, 14 pages, 3 postscript figures included, uses epsf The complete paper, including figures, is also available via anonymous ftp at ftp://ttpux2.physik.uni-karlsruhe.de/ , or via www at http://www-ttp.physik.uni-karlsruhe.de/cgi-bin/preprints/