Threshold Effects in the Decay of Heavy b' and t' Quarks

Understand

A sequential fourth generation is still viable, but the t' and b' quarks are constrained to be not too far apart in mass.

• The t'{\to}bW and b'{\to}tW decay channels are still being pursued at the Tevatron, which would soon be surpassed by the LHC.
• We use a convolution method with up to five-body final state to study t' and b' decays.
• We show how the two decay branches for m_{b'} below the tW threshold, b'{\to}tW^* and t^*W, merge with b'{\to}tW above the threshold.