First extraction of inclusive Vcb from q2 moments
F. U. Bernlochner, Matteo Fael, Kevin Olschewsky, Eric Persson, R. van Tonder, K. Vos, M. Welsch
Abstract
A bstract We present the first determination of V cb from inclusive $$ B\to {X}_c \ell {\overline{v}}_{\ell} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>B</mml:mi> <mml:mo>→</mml:mo> <mml:msub> <mml:mi>X</mml:mi> <mml:mi>c</mml:mi> </mml:msub> <mml:mi>ℓ</mml:mi> <mml:msub> <mml:mover> <mml:mi>v</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> <mml:mi>ℓ</mml:mi> </mml:msub> </mml:math> using moments of the dilepton invariant mass, q 2 . These moments are reparametrization invariant quantities and depend on a reduced set of non-perturbative parameters. This reduced set of parameters opens a new path to extract these parameters up to $$ 1/{m}_b^4 $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mn>1</mml:mn> <mml:mo>/</mml:mo> <mml:msubsup> <mml:mi>m</mml:mi> <mml:mi>b</mml:mi> <mml:mn>4</mml:mn> </mml:msubsup> </mml:math> purely from data and can potentially reduce the uncertainty on V cb . In this paper, we present our first determination of V cb using this method. Combining the recent measurements of q 2 moments by Belle and Belle II, our default fit gives |V cb | = (41 . 69 ± 0 . 63)·10 − 3 . This result presents an important independent cross check of, and is consistent with, the previous state-of-the-art inclusive determinations using lepton energy and hadronic invariant mass moments.