A
bstract
Evidence for the decays
B
0
→
$$ \overline{D} $$
D
¯
0
ϕ
and
B
0
→
$$ \overline{D} $$
D
¯
*0
ϕ
is reported with a significance of 3.6
σ
and 4.3
σ
, respectively. The analysis employs
pp
...collision data at centre-of-mass energies
$$ \sqrt{s} $$
s
= 7, 8 and 13 TeV collected by the LHCb detector and corresponding to an integrated luminosity of 9 fb
−
1
. The branching fractions are measured to be
$$ {\displaystyle \begin{array}{l}\mathcal{B}\left({B}^0\to {\overline{D}}^0\phi \right)=\left(7.7\pm 2.1\pm 0.7\pm 0.7\right)\times {10}^{-7},\\ {}\mathcal{B}\left({B}^0\to {\overline{D}}^{\ast 0}\phi \right)=\left(2.2\pm 0.5\pm 0.2\pm 0.2\right)\times {10}^{-6}.\end{array}} $$
B
B
0
→
D
¯
0
ϕ
=
7.7
±
2.1
±
0.7
±
0.7
×
10
−
7
,
B
B
0
→
D
¯
∗
0
ϕ
=
2.2
±
0.5
±
0.2
±
0.2
×
10
−
6
.
In these results, the first uncertainty is statistical, the second systematic, and the third is related to the branching fraction of the
B
0
→
$$ \overline{D} $$
D
¯
0
K
+
K
−
decay, used for normalisation. By combining the branching fractions of the decays
B
0
→
$$ {\overline{D}}^{\left(\ast \right)0}\phi $$
D
¯
∗
0
ϕ
and
B
0
→
$$ {\overline{D}}^{\left(\ast \right)0}\omega $$
D
¯
∗
0
ω
, the
ω
-
ϕ
mixing angle
δ
is constrained to be tan
2
δ
= (3
.
6 ± 0
.
7 ± 0
.
4) × 10
−
3
, where the first uncertainty is statistical and the second systematic. An updated measurement of the branching fractions of the
$$ {B}_s^0 $$
B
s
0
→
$$ {\overline{D}}^{\left(\ast \right)0}\phi $$
D
¯
∗
0
ϕ
decays, which can be used to determine the CKM angle
γ
, leads to
$$ {\displaystyle \begin{array}{c}\mathcal{B}\left({B}_s^0\to {\overline{D}}^0\phi \right)=\left(2.30\pm 0.10\pm 0.11\pm 0.20\right)\times {10}^{-5},\\ {}\mathcal{B}\left({B}_s^0\to {\overline{D}}^{\ast 0}\phi \right)=\left(3.17\pm 0.16\pm 0.17\pm 0.27\right)\times {10}^{-5}.\end{array}} $$
B
B
s
0
→
D
¯
0
ϕ
=
2.30
±
0.10
±
0.11
±
0.20
×
10
−
5
,
B
B
s
0
→
D
¯
∗
0
ϕ
=
3.17
±
0.16
±
0.17
±
0.27
×
10
−
5
.
A
bstract
This paper reports the observation of the decays
$$ {B}_{(s)}^0 $$
B
s
0
→
D
s
1
(2536)
∓
K
±
using proton-proton collision data collected by the LHCb experiment, corresponding to an ...integrated luminosity of 9 fb
−
1
. The branching fractions of these decays are measured relative to the normalisation channel
B
0
→
$$ \overline{D} $$
D
¯
0
K
+
K
−
. The
D
s
1
(2536)
−
meson is reconstructed in the
$$ \overline{D} $$
D
¯
*
(2007)
0
K
−
decay channel and the products of branching fractions are measured to be
$$ {\displaystyle \begin{array}{c}\mathcal{B}\left({B}_s^0\to {D}_{s1}{(2536)}^{\mp }{K}^{\pm}\right)\times \mathcal{B}\left({D}_{s1}{(2536)}^{-}\to {\overline{D}}^{\ast }{(2007)}^0{K}^{-}\right)\\ {}=\left(2.49\pm 0.11\pm 0.12\pm 0.25\pm 0.06\right)\times {10}^{-5},\\ {}\mathcal{B}\left({B}^0\to {D}_{s1}{(2536)}^{\mp }{K}^{\pm}\right)\times \mathcal{B}\left({D}_{s1}{(2536)}^{-}\to {\overline{D}}^{\ast }{(2007)}^0{K}^{-}\right)\\ {}=\left(0.510\pm 0.021\pm 0.036\pm 0.050\right)\times {10}^{-5}.\end{array}} $$
B
B
s
0
→
D
s
1
2536
∓
K
±
×
B
D
s
1
2536
−
→
D
¯
∗
2007
0
K
−
=
2.49
±
0.11
±
0.12
±
0.25
±
0.06
×
10
−
5
,
B
B
0
→
D
s
1
2536
∓
K
±
×
B
D
s
1
2536
−
→
D
¯
∗
2007
0
K
−
=
0.510
±
0.021
±
0.036
±
0.050
×
10
−
5
.
The first uncertainty is statistical, the second systematic, and the third arises from the uncertainty of the branching fraction of the
B
0
→
$$ \overline{D} $$
D
¯
0
K
+
K
−
normalisation channel. The last uncertainty in the
$$ {B}_s^0 $$
B
s
0
result is due to the limited knowledge of the fragmentation fraction ratio,
f
s
/
f
d
. The significance for the
$$ {B}_s^0 $$
B
s
0
and
B
0
signals is larger than 10
σ
. The ratio of the helicity amplitudes which governs the angular distribution of the
D
s
1
(2536)
−
→
$$ \overline{D} $$
D
¯
*
(2007)
0
K
−
decay is determined from the data. The ratio of the
S
- and
D
-wave amplitudes is found to be 1.11
±
0.15
±
0.06 and the phase difference between them 0.70
±
0.09
±
0.04 rad, where the first uncertainty is statistical and the second systematic.
Abstract
The first study of
$$C\!P$$
C
P
violation in the decay mode
$${{B} ^\pm } \rightarrow {{K} ^+} {{K} ^-} {{\uppi } ^+} {{\uppi } ^-} _{D} h^\pm $$
B
±
→
K
+
K
-
π
+
π
-
D
h
±
, with
...$$h=K,\pi $$
h
=
K
,
π
, is presented, exploiting a data sample of proton–proton collisions collected by the LHCb experiment that corresponds to an integrated luminosity of
$$9\text {\,fb} ^{-1} $$
9
\,fb
-
1
. The analysis is performed in bins of phase space, which are optimised for sensitivity to local
$$C\!P$$
C
P
asymmetries.
$$C\!P$$
C
P
-violating observables that are sensitive to the angle
$$\gamma $$
γ
of the Unitarity Triangle are determined. The analysis requires external information on charm-decay parameters, which are currently taken from an amplitude analysis of LHCb data, but can be updated in the future when direct measurements become available. Measurements are also performed of phase-space integrated observables for
$${{B} ^\pm } \rightarrow {{K} ^+} {{K} ^-} {{\uppi } ^+} {{\uppi } ^-} _{D} h^\pm $$
B
±
→
K
+
K
-
π
+
π
-
D
h
±
and
$${{B} ^\pm } \rightarrow {{\uppi } ^+} {{\uppi } ^-} {{\uppi } ^+} {{\uppi } ^-} _{D} h^\pm $$
B
±
→
π
+
π
-
π
+
π
-
D
h
±
decays.
Abstract
A measurement of
$${{D}} ^0$$
D
0
meson production by the LHCb experiment in its fixed-target configuration is presented. The production of
$${{D}} ^0$$
D
0
mesons is studied with a beam of ...2.5
$$\,\text {Te\hspace{-1.00006pt}V}$$
Te
V
protons colliding on a gaseous neon target at rest, corresponding to a nucleon–nucleon centre-of-mass energy of
$$\sqrt{s_{\scriptscriptstyle \text {NN}}} = 68.5\,\,\text {Ge\hspace{-1.00006pt}V} $$
s
NN
=
68.5
Ge
V
. The sum of the
$${{D}} ^0$$
D
0
and
$${\hspace{0.0pt}\overline{\hspace{0.0pt}{D}}} {}^0$$
D
¯
0
production cross-section in
$$p\text {Ne}$$
p
Ne
collisions in the centre-of-mass rapidity range
$$y^{\star }\in -2.29, 0$$
y
⋆
∈
-
2.29
,
0
is found to be
$$\sigma _{D^{0}}^{y^\star \in -2.29, 0} = 48.2 \pm 0.3 \pm 4.5 \,\upmu \text {b}/\text {nucleon}$$
σ
D
0
y
⋆
∈
-
2.29
,
0
=
48.2
±
0.3
±
4.5
μ
b
/
nucleon
where the first uncertainty is statistical and the second is systematic. The
$${{{D}} ^0}-{{\hspace{0.0pt}\overline{\hspace{0.0pt}{D}}} {}^0} $$
D
0
-
D
¯
0
production asymmetry is also evaluated and suggests a trend towards negative values at large negative
$$y^{\star }$$
y
⋆
. The considered models do not account precisely for all the features observed in the LHCb data, but theoretical predictions including 1
$$\%$$
%
intrinsic charm and 10
$$\%$$
%
recombination contributions better describe the data than the other models considered.
A
bstract
The associated production of prompt
J/ψ
and
Υ
mesons in
pp
collisions at a centre-of-mass energy of
$$ \sqrt{s} $$
s
= 13 TeV is studied using LHCb data, corresponding to an integrated ...luminosity of 4 fb
−
1
. The measurement is performed for
J/ψ
(
Υ
) mesons with a transverse momentum
p
T
<
10 (30) GeV/
c
in the rapidity range 2
.
0
< y <
4
.
5. In this kinematic range, the cross-section of the associated production of prompt
J/ψ
and
Υ
(1
S
) mesons is measured to be 133 ± 22 ± 7 ± 3 pb, with a significance of 7
.
9
σ
, and that of prompt
J/ψ
and
Υ
(2
S
) mesons to be 76 ± 21 ± 4 ± 7 pb, with a significance of 4
.
9
σ
. The first uncertainty is statistical, the second systematic, and the third due to uncertainties on the used branching fractions. This is the first observation of the associated production of
J/ψ
and
Υ
(1
S
) in proton-proton collisions. Differential cross-sections are measured as functions of variables that are sensitive to kinematic correlations between the
J/ψ
and
Υ
(1
S
) mesons. The effective cross-sections of the associated production of prompt
J/ψ
and
Υ
mesons are obtained and found to be compatible with measurements using other particle productions.
A
bstract
The first observation of the
$$ {B}_s^0 $$
B
s
0
→ D
∗+
D
∗
−
decay and the measurement of its branching ratio relative to the
B
0
→ D
∗+
D
∗
−
decay are presented. The data sample used ...corresponds to an integrated luminosity of 9 fb
−
1
of proton-proton collisions recorded by the LHCb experiment at centre-of-mass energies of 7, 8 and 13 TeV between 2011 and 2018. The decay is observed with more than 10 standard deviations and the time-integrated ratio of branching fractions is determined to be
$$ \frac{\mathcal{B}\left({B}_s^0\to {D}^{\ast +}{D}^{\ast -}\right)}{\mathcal{B}\left({B}^0\to {D}^{\ast +}{D}^{\ast -}\right)}=0.269\pm 0.032\pm 0.011\pm 0.008, $$
B
B
s
0
→
D
∗
+
D
∗
−
B
B
0
→
D
∗
+
D
∗
−
=
0.269
±
0.032
±
0.011
±
0.008
,
where the first uncertainty is statistical, the second systematic and the third due to the uncertainty of the fragmentation fraction ratio
f
s
/f
d
. The
$$ {B}_s^0 $$
B
s
0
→ D
*+
D
*
−
branching fraction is calculated to be
$$ \mathcal{B}\left({B}_s^0\to {D}^{\ast +}{D}^{\ast -}\right)=\left(2.15\pm 0.26\pm 0.09\pm 0.06\pm 0.16\right)\times {10}^{-4}, $$
B
B
s
0
→
D
∗
+
D
∗
−
=
2.15
±
0.26
±
0.09
±
0.06
±
0.16
×
10
−
4
,
where the fourth uncertainty is due to the
B
0
→ D
*
+
D
*−
branching fraction. These results are calculated using the average
$$ {B}_s^0 $$
B
s
0
meson lifetime in simulation. Correction factors are reported for scenarios where either a purely heavy or a purely light
$$ {B}_s^0 $$
B
s
0
eigenstate is considered.
A
bstract
The first observation of the
$$ {B}_s^0 $$
B
s
0
→
(
χ
c
1
(3872)
→ J/ψπ
+
π
−
)
π
+
π
−
decay is reported using proton-proton collision data, corresponding to integrated luminosities of 1, ...2 and 6 fb
−
1
, collected by the LHCb experiment at centre-of-mass energies of 7, 8 and 13 TeV, respectively. The ratio of branching fractions relative to the
$$ {B}_s^0 $$
B
s
0
→
(
ψ
(2
S
)
→ J/ψπ
+
π
−
)
π
+
π
−
decay is measured to be
$$ \frac{\mathcal{B}\left({B}_s^0\to {\chi}_{c1}(3872){\pi}^{+}{\pi}^{-}\right)\times \mathcal{B}\left({\chi}_{c1}(3872)\to J/\psi {\pi}^{+}{\pi}^{-}\right)}{\mathcal{B}\left({B}_s^0\to \psi (2S){\pi}^{+}{\pi}^{-}\right)\times \mathcal{B}\left(\psi (2S)\to J/\psi {\pi}^{+}{\pi}^{-}\right)}=\left(6.8\pm 1.1\pm 0.2\right)\times {10}^{-2}, $$
B
B
s
0
→
χ
c
1
3872
π
+
π
−
×
B
χ
c
1
3872
→
J
/
ψ
π
+
π
−
B
B
s
0
→
ψ
2
S
π
+
π
−
×
B
ψ
2
S
→
J
/
ψ
π
+
π
−
=
6.8
±
1.1
±
0.2
×
10
−
2
,
where the first uncertainty is statistical and the second systematic. The mass spectrum of the
π
+
π
−
system recoiling against the
χ
c
1
(3872) meson exhibits a large contribution from
$$ {B}_s^0 $$
B
s
0
→ χ
c
1
(3872) (
f
0
(980)
→ π
+
π
−
) decays.
A
bstract
The first observation of the
$$ {\Lambda}_b^0\to {D}_s^{-}p $$
Λ
b
0
→
D
s
−
p
decay is presented using proton-proton collision data collected by the LHCb experiment at a centre-of-mass ...energy of
$$ \sqrt{s} $$
s
= 13 TeV, corresponding to a total integrated luminosity of 6 fb
−
1
. Using the
$$ {\Lambda}_b^0\to {\Lambda}_c^{+}{\pi}^{-} $$
Λ
b
0
→
Λ
c
+
π
−
decay as the normalisation mode, the branching fraction of the
$$ {\Lambda}_b^0\to {D}_s^{-}p $$
Λ
b
0
→
D
s
−
p
decay is measured to be
$$ \mathcal{B}\left({\Lambda}_b^0\to {D}_s^{-}p\right)=\left(12.6\pm 0.5\pm 0.3\pm 1.2\right)\times {10}^{-6} $$
B
Λ
b
0
→
D
s
−
p
=
12.6
±
0.5
±
0.3
±
1.2
×
10
−
6
, where the first uncertainty is statistical, the second systematic and the third due to uncertainties in the branching fractions of the
$$ {\Lambda}_b^0\to {\Lambda}_c^{+}{\pi}^{-} $$
Λ
b
0
→
Λ
c
+
π
−
,
$$ {D}_s^{-}\to {K}^{-}{K}^{+}{\pi}^{-} $$
D
s
−
→
K
−
K
+
π
−
and
$$ {\Lambda}_c^{+}\to p{K}^{-}{\pi}^{+} $$
Λ
c
+
→
p
K
−
π
+
decays.
A
bstract
A search for direct
CP
violation in the Cabibbo-suppressed decay
$$ {D}_s^{+} $$
D
s
+
→ K
−
K
+
K
+
and in the doubly Cabibbo-suppressed decay
D
+
→
K
−
K
+
K
+
is reported. The analysis ...is performed with data collected by the LHCb experiment in proton-proton collisions at a centre-of-mass energy of 13 TeV corresponding to an integrated luminosity of 5.6 fb
−
1
. The search is conducted by comparing the
$$ {D}_{(s)}^{+} $$
D
s
+
and
$$ {D}_{(s)}^{-} $$
D
s
−
Dalitz-plot distributions through a model-independent binned technique, based on fits to the
K
−
K
+
K
+
invariant-mass distributions, with a total of 0.97 (1.27) million
$$ {D}_s^{+} $$
D
s
+
(
D
+
) signal candidates. The results are given as
p
-values for the hypothesis of
CP
conservation and are found to be 13.3% for the
$$ {D}_s^{+} $$
D
s
+
→ K
−
K
+
K
+
decay and 31.6% for the
D
+
→ K
−
K
+
K
+
decay. No evidence for
CP
violation is observed in these decays.
The production cross-sections of (sic) mesons, namely (sic)(1S), (sic)(2S) and (sic)(3S), in pp collisions at root s = 5TeV are measured with a data sample corresponding to an integrated luminosity ...of 9.13 +/- 0.18 pb(-1) collected by the LHCb detector. The (sic) mesons are reconstructed in the decay mode (sic) -> mu(+)mu(-). Double differential cross-sections times branching fractions, as functions of the transverse momentum p(T) and the rapidity y of the (sic) mesons, are measured in the range pT < 20 GeV/ c and 2.0 < y < 4.5. The results integrated over these pT and y ranges are sigma((sic)(1S)) x B((sic)(1S) -> mu(+) mu(-)) = 2101 +/- 33 +/- 83 pb, sigma((sic)(2S)) x B((sic)(2S) -> mu(+) mu(-)) = 526 +/- 20 +/- 21 pb, sigma((sic)(3S)) x B((sic)(3S) -> mu(+) mu(-)) = 242 +/- 16 +/- 10 pb, where the first uncertainties are statistical and the second are systematic. The ratios of cross-sections between measurements of two different (sic) states and between measurements at different centre-of-mass energies are determined. The nuclear modification factor of (sic)(1S) at root s = 5TeV is updated as well using the directly measured cross-section results from this analysis.
