# First observation of the charmless beauty decay $$\lambda\frac{0}{b}$$→pKη'

Williams, Timothy (2018). First observation of the charmless beauty decay $$\lambda\frac{0}{b}$$→pKη'. University of Birmingham. Ph.D.

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## Abstract

A search is performed for the decay $$\lambda\frac{0}{b}$$→pKη' using pp collision data collected with the LHCb detector at centre-of-mass energies of $$\sqrt{s}$$ = 7TeV and $$\sqrt{s}$$ = 8TeV, corresponding to an integrated luminosity of 3 fb$$^-$$$$^1$$. The search is performed in two decay channels; the η' is reconstructed through the decays η'→$$\pi^+\pi^-\gamma$$ and η'→$$\pi^+\pi^-\eta$$. In the η'→$$\pi^+\pi^-\gamma$$ decay channel 117 ± 15(stat.) ± 10(sys.) signal events are observed and 45 ± 8(stat.) ± 2(sys.) signal events are observed in the η'→$$\pi^+\pi^-\eta$$ decay channel. The combined statistical significance of these signals is 12.0σ, therefore this is the first observation of the decay $$\lambda\frac{0}{b}$$→pKη' . The branching fraction of the decay $$\lambda\frac{0}{b}$$→pKη' is measured relative to the decay B$$^+$$→K$$^+$$η'.
The ratio of branching fractions is measured to be

$$\frac{\beta(\lambda\frac{0}{b}→pKη')}{\beta(B^+→K^+η'}$$= 0.120 ± 0.013(stat.) ± 0.013(sys.).

Using the world average value for the branching fraction of the decay B$$^+$$→K$$^+$$η', the branching fraction of $$\lambda\frac{0}{b}$$→pKη' is measured to be,
$$\beta$$$$(\lambda\frac{0}{b}→pKη')$$ = 8.48 ± 0.88(stat.) ± 0.97(sys.) x 10$$^-$$$$^6$$
.
This is the first observation of a b-baryon decaying to an η.

Type of Work: Thesis (Doctorates > Ph.D.)
Award Type: Doctorates > Ph.D.
Supervisor(s):
Supervisor(s)EmailORCID
Watson, NigelUNSPECIFIEDUNSPECIFIED