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The journal of high energy physics, 2019-09, Vol.2019 (9), p.1-45, Article 103
Ort / Verlag
Berlin/Heidelberg: Springer Berlin Heidelberg
Erscheinungsjahr
2019
Link zum Volltext
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Beschreibungen/Notizen
A
bstract
We perform a general model-independent analysis of
b
→
cτ
ν
¯
τ
transitions, including measurements of ℛ
D
, ℛ
D
∗
, their
q
2
differential distributions, the recently measured longitudinal
D
* polarization
F
L
D
∗
, and constraints from the
B
c
→
τ
ν
¯
τ
lifetime, each of which has significant impact on the fit. A global fit to a general set of Wilson coefficients of an effective low-energy Hamiltonian is presented, the solutions of which are interpreted in terms of hypothetical new-physics mediators. From the obtained results we predict selected
b
→
cτ
ν
¯
τ
observables, such as the baryonic transition
Λ
b
→
Λ
c
τ
ν
¯
τ
, the ratio ℛ
J
/
ψ
, the forward-backward asymmetries
A
FB
D
∗
, the
τ
polarization asymmetries
P
τ
D
∗
, and the longitudinal
D
* polarization fraction
F
L
D
∗
. The latter shows presently a slight tension with any new-physics model, such that an improved measurement could have an important impact. We also discuss the potential change due the very recently announced preliminary
ℛ
D
∗
measurement by the Belle collaboration.