The data sample of Λ0b→J/ψpK− decays acquired with the LHCb detector from 7 and 8 TeV pp collisions, corresponding to an integrated luminosity of 3 fb−1, is inspected for the presence of J/ψp or ...J/ψK− contributions with minimal assumptions about K−p contributions. It is demonstrated at more than nine standard deviations that Λ0b→J/ψpK− decays cannot be described with K−p contributions alone, and that J/ψp contributions play a dominant role in this incompatibility. These model-independent results support the previously obtained model-dependent evidence for P+c→J/ψp charmonium-pentaquark states in the same data sample.
A full amplitude analysis of Λ0b→J/ψpπ− decays is performed with a data sample acquired with the LHCb detector from 7 and 8 TeV pp collisions, corresponding to an integrated luminosity of 3 fb−1. A ...significantly better description of the data is achieved when, in addition to the previously observed nucleon excitations N→pπ−, either the Pc(4380)+ and Pc(4450)+→J/ψp states, previously observed in Λ0b→J/ψpK− decays, or the Zc(4200)−→J/ψπ− state, previously reported in B0→J/ψK+π− decays, or all three, are included in the amplitude models. The data support a model containing all three exotic states, with a significance of more than three standard deviations. Within uncertainties, the data are consistent with the Pc(4380)+ and Pc(4450)+ production rates expected from their previous observation taking account of Cabibbo suppression.
In the Standard Model of particle physics, the strength of the couplings of the b quark to the u and c quarks, |Vub| and |Vcb|, are governed by the coupling of the quarks to the Higgs boson. Using ...data from the LHCb experiment at the Large Hadron Collider, the probability for the Λb0 baryon to decay into the p final state relative to the final state is measured. Combined with theoretical calculations of the strong interaction and a previously measured value of |Vcb|, the first |Vub| measurement to use a baryonic decay is performed. This measurement is consistent with previous determinations of |Vub| using B meson decays to specific final states and confirms the existing incompatibility with those using an inclusive sample of final states.
A search for CP violation in D-0 -> K-K+ and D-0 -> pi(-)pi(+) decays is performed using pp collision data, corresponding to an integrated luminosity of 3 fb(-1), collected using the LHCb detector at ...center-of-mass energies of 7 and 8 TeV. The flavor of the charm meson is inferred from the charge of the pion in D*(+) -> D-0 pi(+) and D*(-) -> (D) over bar (0)pi(-) decays. The difference between the CP asymmetries in D-0 -> K-K+ and D-0 -> pi(-)pi(+) decays, Delta A(CP) A(CP)(K-K+) - A(CP)(pi(-)pi(+)), is measured to be -0.10 +/- 0.08(stat) +/- 0.03(syst)%. This is the most precise measurement of a time-integrated CP asymmetry in the charm sector from a single experiment.
The production of the
η
c
(
1
S
)
state in proton-proton collisions is probed via its decay to the
p
p
¯
final state with the LHCb detector, in the rapidity range
2.0
<
y
<
4.5
and in the meson ...transverse-momentum range
p
T
>
6.5
GeV
/
c
. The cross-section for prompt production of
η
c
(
1
S
)
mesons relative to the prompt
J
/
ψ
cross-section is measured, for the first time, to be
σ
η
c
(
1
S
)
/
σ
J
/
ψ
=
1.74
±
0.29
±
0.28
±
0
.
18
B
at a centre-of-mass energy
s
=
7
TeV
using data corresponding to an integrated luminosity of 0.7 fb
-
1
, and
σ
η
c
(
1
S
)
/
σ
J
/
ψ
=
1.60
±
0.29
±
0.25
±
0
.
17
B
at
s
=
8
TeV
using 2.0 fb
-
1
. The uncertainties quoted are, in order, statistical, systematic, and that on the ratio of branching fractions of the
η
c
(
1
S
)
and
J
/
ψ
decays to the
p
p
¯
final state. In addition, the inclusive branching fraction of
b
-hadron decays into
η
c
(
1
S
)
mesons is measured, for the first time, to be
B
(
b
→
η
c
X
)
=
(
4.88
±
0.64
±
0.29
±
0
.
67
B
)
×
10
-
3
, where the third uncertainty includes also the uncertainty on the
J
/
ψ
inclusive branching fraction from
b
-hadron decays. The difference between the
J
/
ψ
and
η
c
(
1
S
)
meson masses is determined to be
114.7
±
1.5
±
0.1
MeV
/
c
2
.
A
bstract
A study is presented of central exclusive production of Υ(
nS
) states, where the Υ(
nS
) resonances decay to the
μ
+
μ
−
final state, using
pp
collision data recorded by the LHCb ...experiment. The cross-section is measured in the rapidity range 2
< y
(Υ)
<
4
.
5 where the muons are reconstructed in the pseudorapidity range 2
< η
(
μ
±
)
<
4
.
5. The data sample corresponds to an integrated luminosity of 2.9 fb
−1
and was collected at centre-of-mass energies of 7 TeV and 8 TeV. The measured Υ(1
S
) and Υ(2
S
) production cross-sections are
σ
pp
→
p
Υ
1
S
p
=
9.0
±
2.1
±
1.7
p
b
and
σ
pp
→
p
Υ
2
S
p
=
1.3
±
0.8
±
0.3
p
b
,
where the first uncertainties are statistical and the second are systematic. The Υ(1
S
) crosssection is also measured as a function of rapidity and is found to be in good agreement with Standard Model predictions. An upper limit is set at 3.4 pb at the 95% confidence level for the exclusive Υ(3
S
) production cross-section, including possible contamination from χ
b
(3
P
) → Υ(3
S
)γ decays.
A
bstract
Associated production of bottomonia and open charm hadrons in pp collisions at
s
=
7
and 8 TeV is observed using data corresponding to an integrated luminosity of 3 fb
−1
accumulated with ...the LHCb detector. The observation of five combinations, Y(1S)D
0
, Y(2S)D
0
, Y(1S)D
+
, Y(2S)D
+
and Y(1S)D
s
+
, is reported. Production crosssections are measured for Y(1S)D
0
and Y(1S)D
+
pairs in the forward region. The measured cross-sections and the differential distributions indicate the dominance of double parton scattering as the main production mechanism.
A
bstract
The production of
J/ψ
mesons in proton-proton collisions at a centre-of-mass energy of
s
=
13
TeV is studied with the LHCb detector. Cross-section measurements are performed as a function ...of the transverse momentum
p
T
and the rapidity
y
of the
J/ψ
meson in the region
p
T
<
14 GeV/
c
and 2
.
0
< y <
4
.
5, for both prompt
J/ψ
mesons and
J/ψ
mesons from
b
-hadron decays. The production cross-sections integrated over the kinematic coverage are 15
.
30 ± 0
.
03 ± 0
.
86 μb for prompt
J/ψ
and 2
.
34 ± 0
.
01 ± 0
.
13 μb for
J/ψ
from
b
-hadron decays, assuming zero polarization of the
J/
ψ meson. The first uncertainties are statistical and the second systematic. The cross-section reported for
J/ψ
mesons from
b
-hadron decays is used to extrapolate to a total
b
b
¯
cross-section. The ratios of the cross-sections with respect to
s
=
8
TeV are also determined.
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