• DOI:10.1103/PHYSREVD.102.054511
• Corpus ID: 218502542

Charmonium properties from lattice QCD+QED : Hyperfine splitting, J/ψ leptonic width, charm quark mass, and aμc

@article{Hatton2020CharmoniumPF,
  title={Charmonium properties from lattice 
QCD+QED
: Hyperfine splitting, 
J/$\psi$
 leptonic width, charm quark mass, and 
a$\mu$c},
  author={D. Hatton and Christine T. H. Davies and B. Galloway and Jonna Koponen and G. Peter Lepage and Andrew Lytle},
  journal={Physical Review D},
  year={2020}
}

• D. Hatton, C. Davies, +3 authors A. Lytle
• Published 4 May 2020
• Physics
• Physical Review D

We have performed the first
n
f
=
2
+
1
+
1
lattice QCD computations of the properties (masses and decay constants) of ground-state charmonium mesons. Our calculation uses the HISQ action to generate quark-line connected two-point correlation functions on MILC gluon field configurations that include
u
/
d
quark masses going down to the physical point, tuning the
c
quark mass from
M
J
/
ψ
and including the effect of the
c
quark’s electric charge through quenched QED. We obtain
M
J
/
ψ
−
M
η
c
(connected) = 120.3(1.1) MeV and interpret the difference with experiment as the impact on
M
η
c
of its decay to gluons, missing from the lattice calculation. This allows us to determine
Δ
M
a
n
n
i
h
i
l
n
η
c
=+7.3(1.2) MeV, giving its value for the first time. Our result of
f
J
/
ψ
=
0.4104(17) GeV, gives
Γ
(
J
/
ψ
→
e
+
e
−
)
=5.637(49) keV, in agreement with, but now more accurate than experiment. At the same time we have improved the determination of the
c
quark mass, including the impact of quenched QED to give
m
c
(
3
G
e
V
)
= 0.9841(51) GeV. We have also used the time-moments of the vector charmonium current-current correlators to improve the lattice QCD result for the
c
quark HVP contribution to the anomalous magnetic moment of the muon. We obtain
a
c
μ
=
14.638
(
47
)
×
10
−
10
, which is 2.5
σ
higher than the value derived using moments extracted from some sets of experimental data on
R
(
e
+
e
−
→
h
a
d
r
o
n
s
)
. This value for
a
c
μ
includes our determination of the effect of QED on this quantity,
δ
a
c
μ
=
0.0313
(
28
)
×
10
−
10
.