nLab V_cb puzzle

Contents

matter field fermions (spinors, Dirac fields)

flavors of fundamental fermions in the standard model of particle physics:
generation of fermions	1st generation	2nd generation	3d generation
quarks ( $q$ )
up-type	up quark ( $u$ )	charm quark ( $c$ )	top quark ( $t$ )
down-type	down quark ( $d$ )	strange quark ( $s$ )	bottom quark ( $b$ )
leptons
charged	electron	muon	tauon
neutral	electron neutrino	muon neutrino	tau neutrino

bound states:
mesons	light mesons: pion ( $u d$ ) ρ-meson ( $u d$ ) ω-meson ( $u d$ ) f1-meson a1-meson	strange-mesons: ϕ-meson ( $s \bar s$ ), kaon, K-meson ( $u s$ , $d s$ ) eta-meson ( $u u + d d + s s$ ) charmed heavy mesons*: D-meson ( $u c$ , $d c$ , $s c$ ) J/ψ-meson ( $c \bar c$ )	bottom heavy mesons: B-meson ( $q b$ ) ϒ-meson ( $b \bar b$ )
baryons	nucleons: proton $(u u d)$ neutron $(u d d)$

hadrons (bound states of the above quarks)

bosinos:

dark matter candidates

Exotica

auxiliary fields

Idea

In particle physics, what is called the $V_{cb}$ -puzzle (status updates in GJS 19, Ricciardi 21) is an observation about the semileptonic decay of B-mesons (by the Belle collaboration and other experiments) which implies a value of the element $\left\vert V_{c b}\right\vert$ in the CKM matrix that differs from the apparent prediction of the standard model of particle physics with a statistical significance of about $3 \sigma$ . But the form factors involved in this prediction suffer from theoretical uncertainties of quark contributions, and further lattice QCD-computation is expected to be required to clarify the actual prediction of the standard model of particle physics (GJS 19, last sentence).

The $V_{c b}$ -puzzle is different from, but related to, the flavour anomalies (GJS 19 (6))

Paolo Gambino, Martin Jung, Stefan Schacht, The $V_{c b}$ puzzle: an update (arXiv:1905.08209)
Giulia Ricciardi, Semileptonic B decays and $\vert V_{x b}\vert$ update (arXiv:2103.06099)

With emphasis on lattice QCD-computations:

Last revised on April 1, 2021 at 04:33:28. See the history of this page for a list of all contributions to it.