Study of $B \to KK\ell\nu_\ell$ decays at Belle

Lubej, Matic (author), Zupanc, Anže (mentor)

We present the branching fraction measurement of the charmless semileptonic decay $B^+ \to K^+K^-\ell^+\nu_\ell$. The measurement has been performed on a data sample corresponding to 710 $\rm{fb^{-1}}$ of integrated luminosity, collected with the Belle detector at the KEKB asymmetric-energy $e^+$$e^-$ collider in Tsukuba, Japan. We present the results obtained with the B2BII data format converter. This is the first measurement of the decay, where we obtain the branching fraction of $\mathcal{B}(B^+ \to K^+K^-\ell^+\nu) = (3.04 \pm 0.51 \pm ^{+0.67} _{-0.66}) \times 10^{-5}$. With the signal significance of 4.6$\sigma$, this measurement counts as the first evidence for the decay.

• Language: English
• Keywords: detektor Belle, mezoni B, semileptonski razpadi, razvejitveno razmerje
• Work type: Doctoral dissertation
• Typology: 2.08 - Doctoral Dissertation
• Organization: FMF - Faculty of Mathematics and Physics
• Year: 2018
• PID: 20.500.12556/RUL-105432
• COBISS.SI-ID: 3271012
• Publication date in RUL: 29.11.2018

Secondary language

• Language: Slovenian
• Title: Študija razpadov $B \to KK\ell\nu_\ell$ pri Belle

Abstract

V disertaciji predstavljamo meritev razvejitvenega razmerja ne-čarobnega semileptonskega razpada $B^+ \to K^+K^-\ell^+\nu_\ell$. Meritev je bila opravljena na vzorcu podatkov, ki ustreza integrirani luminoznosti 710 $\rm{fb^{-1}}$, zbranim z detektorjem Belle na asimetričnem trkalniku delcev $e^+$$e^-$ KEKB v mestu Tsukuba, na Japonskem. V delu predstavimo rezultate, ki so bili pridobljeni s konverzijo B2BII. To je prva meritev tega razpada, kjer izmerimo razvejitveno razmerje $\mathcal{B}(B^+ \to K^+K^-\ell^+\nu) = (3.04 \pm 0.51 \pm ^{+0.67} _{-0.66}) \times 10^{-5}$. S signifikanco 4.6$\sigma$ ta meritev šteje kot prvi dokaz za ta razpad.

• Keywords: Belle detector, B mesons, semileptonic decays, branching fraction, inclusive tagging, untagged, rest of event