Note on new interesting baryon channels to measure the photon polarization in b -> s gamma

Abstract

At LHC a large number of b-flavored baryons will be produced. In this note we propose new baryon modes to determine the photon helicity of the penguin transition $b\to s\gamma$. The decay ${\Lambda }_b\to \Lambda \gamma$ has the drawback that the $\Lambda$, being neutral and long-lived, will escape detection most of the time. To overcome this difficulty, transitions of the type ${\Lambda }_b\to {\Lambda }^{\ast }\gamma$ have been proposed, where ${\Lambda }^{\ast }$ denotes an excited state decaying strongly within the detector into the clean mode $p{K}^{-}$. The doublet ${\Xi }_b$, that decays weakly, has a number of good features. The charged baryon ${\Xi }_b^{-}$ will decay into the mode ${\Xi }^{-}\gamma$, where the ground state hyperon ${\Xi }^{-}$, although it will decay most of the time outside the detector, can be detected because it is charged. We consider also the decay of ${\Xi }_b$ into ${\Xi }^{\ast }\gamma$, where a higher mass state ${\Xi }^{\ast }$ can decay strongly within the detector. We point out that the initial transverse polarization of ${\Xi }_b$ has to be known in all cases. To determine this parameter through the transition ${\Xi }_b\to J/\Psi \Xi$, we distinguish between different cases, and underline that in some situations one needs {\it theoretical input} on the asymmetry parameter ${\alpha }_{{\Xi }_b}$ of the primary decay. {\it A fortiori} the same considerations apply to the case of the ${\Lambda }_b$.

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Cited by in corpus (7)

• Form Factors for Lambda_b -> Lambda Transitions in SCET
• The exclusive rare decay b->s gamma of heavy b-Baryons
• Angular analysis of B -> J/psi K1 : towards a model independent determination of the photon polarization with B-> K1 gamma
• Radiative $b$-baryon decays to measure the photon and $b$-baryon polarization
• Measurement of the mass difference and relative production rate of the ${\Omega }_b^{-}$ and ${\Xi }_b^{-}$ baryons
• Observation of the ${\Lambda }_b^0\to J/\psi {\Xi }^{-}{K}^{+}$ and ${\Xi }_b^0\to J/\psi {\Xi }^{-}{\pi }^{+}$ decays
• Di-vector boson production in association with a Higgs boson at hadron colliders