Abstract
Using a proton–proton collision data sample collected by the LHCb detector and corresponding to an integrated luminosity of
$$5.7~\text {fb}^{-1}$$
5.7
fb
-
1
, the lifetime of the light
...$${{B} ^0_{s}} $$
B
s
0
mass eigenstate,
$$\tau _{L}$$
τ
L
, is measured using the
$$B^0_s \rightarrow J/\psi \eta $$
B
s
0
→
J
/
ψ
η
decay mode to be
$$\begin{aligned} \tau _{\text {L}} = 1.445 \pm 0.016 \text {(stat)} \pm 0.008 \text {(syst)} \,\text {ps}. \end{aligned}$$
τ
L
=
1.445
±
0.016
(stat)
±
0.008
(syst)
ps
.
A combination of this result with a previous LHCb analysis using an independent dataset corresponding to 3 fb
$$^{-1}$$
-
1
of integrated luminosity gives
$$\begin{aligned} \tau _{\text {L}} = 1.452 \pm 0.014 \pm 0.007 \pm 0.002 \,\text {ps}, \end{aligned}$$
τ
L
=
1.452
±
0.014
±
0.007
±
0.002
ps
,
where the first uncertainty is statistical, the second due to the uncorrelated part of the systematic uncertainty and the third due to the correlated part of the systematic uncertainty.
A
bstract
A precision measurement of the
$$ {B}_c^{+} $$
B
c
+
meson mass is performed using proton- proton collision data collected with the LHCb experiment at centre-of-mass energies of 7
,
8 and ...13 TeV, corresponding to a total integrated luminosity of 9
.
0 fb
−
1
. The
$$ {B}_c^{+} $$
B
c
+
mesons are reconstructed via the decays
$$ {B}_c^{+} $$
B
c
+
→ J/ψπ
+
,
$$ {B}_c^{+} $$
B
c
+
→ J/ψπ
+
π
−
π
+
,
$$ {B}_c^{+}\to J/\psi p\overline{p}{\pi}^{+} $$
B
c
+
→
J
/
ψp
p
¯
π
+
,
$$ {B}_c^{+}\to J/\psi {D}_s^{+} $$
B
c
+
→
J
/
ψ
D
s
+
,
$$ {B}_c^{+} $$
B
c
+
→ J/ψ D
0
K
+
and
$$ {B}_c^{+}\to {B}_s^0{\pi}^{+} $$
B
c
+
→
B
s
0
π
+
. Combining the results of the individual decay channels, the
$$ {B}_c^{+} $$
B
c
+
mass is measured to be 6274
.
47
±
0
.
27 (stat)
±
0
.
17 (syst) MeV
/c
2
. This is the most precise measurement of the
$$ {B}_c^{+} $$
B
c
+
mass to date. The difference between the
$$ {B}_c^{+} $$
B
c
+
and
$$ {B}_s^0 $$
B
s
0
meson masses is measured to be 907
.
75
±
0
.
37 (stat)
±
0
.
27 (syst) MeV
/c
.
This paper presents an analysis of the \( {\Lambda}_b^0 \) → J/ψΛ angular distribution and the transverse production polarisation of \( {\Lambda}_b^0 \) baryons in proton-proton collisions at ...centre-of-mass energies of 7, 8 and 13 TeV. The measurements are performed using data corresponding to an integrated luminosity of 4.9 fb–1, collected with the LHCb experiment. The polarisation is determined in a fiducial region of \( {\Lambda}_b^0 \) transverse momentum and pseudorapidity of 1 < pT < 20 GeV/c and 2 < η < 5, respectively. The data are consistent with \( {\Lambda}_b^0 \) baryons being produced unpolarised in this region. The parity-violating asymmetry parameter of the Λ → pπ– decay is also determined from the data and its value is found to be consistent with a recent measurement by the BES III collaboration.
A
bstract
A measurement of the
$$ {\varXi}_{cc}^{++} $$
Ξ
cc
+
+
mass is performed using data collected by the LHCb experiment between 2016 and 2018 in
pp
collisions at a centre-of-mass energy of 13 ...TeV, corresponding to an integrated luminosity of 5
.
6 fb
−
1
. The
$$ {\varXi}_{cc}^{++} $$
Ξ
cc
+
+
candidates are reconstructed via the decay modes
$$ {\varXi}_{cc}^{++}\to {\varLambda}_c^{+}{K}^{-}{\pi}^{+}{\pi}^{+} $$
Ξ
cc
+
+
→
Λ
c
+
K
−
π
+
π
+
and
$$ {\varXi}_{cc}^{++}\to {\varXi}_c^{+}{\pi}^{+} $$
Ξ
cc
+
+
→
Ξ
c
+
π
+
. The result, 3621
.
55
±
0
.
23 (stat)
±
0
.
30 (syst) MeV/
c
2
, is the most precise measurement of the
$$ {\varXi}_{cc}^{++} $$
Ξ
cc
+
+
mass to date.
A
bstract
The Cabibbo-suppressed semileptonic decay
$$ {B}^{+}\to p\overline{p}{\mu}^{+}{\nu}_{\mu } $$
B
+
→
p
p
¯
μ
+
ν
μ
is observed for the first time using a sample of
pp
collisions ...corresponding to an integrated luminosity of 1.0, 2.0 and 1.7 fb
−
1
at centre-of-mass energies of 7, 8 and 13 TeV, respectively. The differential branching fraction is measured as a function of the
$$ p\overline{p} $$
p
p
¯
invariant mass using the decay mode
B
+
→ J/ψK
+
for normalisation. The total branching fraction is measured to be
$$ \mathrm{\mathcal{B}}\left({B}^{+}\to p\overline{p}{\mu}^{+}{\nu}_{\mu}\right)=\left({5.27}_{-0.24}^{+0.23}\pm 0.21\pm 0.15\right)\times {10}^{-6}, $$
ℬ
B
+
→
p
p
¯
μ
+
ν
μ
=
5.27
−
0.24
+
0.23
±
0.21
±
0.15
×
10
−
6
,
where the first uncertainty is statistical, the second systematic and the third is from the uncertainty on the branching fraction of the normalisation channel.
A
bstract
The decay-time-dependent
CP
asymmetry in
B
0
→ D
∗±
D
∓
decays is mea- sured using a data set corresponding to an integrated luminosity of 9 fb
−
1
recorded by the LHCb detector in ...proton-proton collisions at centre-of-mass energies of 7, 8 and 13 TeV. The
CP
parameters are measured as
S
D
∗
D
=
−
0.861
±
0.077
stat
±
0.019
syst
,
Δ
S
D
∗
D
=
0.019
±
0.075
stat
±
0.012
syst
,
C
D
∗
D
=
−
0.059
±
0.092
stat
±
0.020
syst
,
ΔC
D
∗
D
=
−
0.031
±
0.092
stat
±
0.016
syst
,
A
D
∗
D
=
0.008
±
0.014
stat
±
0.006
syst
.
The analysis provides the most precise single measurement of
CP
violation in this decay channel to date. All parameters are consistent with their current world average values.
PDF
