A
bstract
The
CP
asymmetries of seven
B
−
decays to two charm mesons are measured using data corresponding to an integrated luminosity of 9 fb
−
1
of proton-proton collisions collected by the LHCb ...experiment. Decays involving a
D
*0
or
D
s
∗
−
meson are analysed by reconstructing only the
D
0
or
D
s
−
decay products. This paper presents the first measurement of
A
CP
(
B
−
→
D
s
∗
−
D
0
) and
A
CP
(
B
−
→
D
s
−
D
∗
0
), and the most precise measurement of the other five
CP
asymmetries. There is no evidence of
CP
violation in any of the analysed decays. Additionally, two ratios between branching fractions of selected decays are measured.
A
bstract
A search is performed for a spin-0 boson,
ϕ
, produced in proton-proton collisions at centre-of-mass energies of 7 and 8 TeV, using prompt
ϕ
→ μ
+
μ
−
decays and a data sample corresponding ...to an integrated luminosity of approximately 3.0 fb
−1
collected with the LHCb detector. No evidence is found for a signal in the mass range from 5.5 to 15 GeV. Upper limits are placed on the product of the production cross-section and the branching fraction into the dimuon final state. The limits are comparable to the best existing over most of the mass region considered and are the first to be set near the ϒ resonances.
A
bstract
A search for
CP
violation in D
0
→
π
−
π
+
π
0
decays is reported, using
pp
collision data collected by the LHCb experiment from 2015 to 2018 corresponding to an integrated luminosity of 6 ...fb
−
1
. An unbinned model-independent approach provides sensitivity to local
CP
violation within the two-dimensional phase space of the decay. The method is validated using the Cabibbo-favoured channel D
0
→ K
−
π
+
π
0
and background regions of the signal mode. The results are consistent with
CP
symmetry in this decay.
Observation of the B+→ Jψη′K+ decay Alessio, F.; Aliouche, Z.; Artamonov, A. ...
The journal of high energy physics,
08/2023, Letnik:
2023, Številka:
8
Journal Article
Recenzirano
Odprti dostop
A
bstract
The
B
+
→
Jψη
′
K
+
decay is observed for the first time using proton-proton collision data collected by the LHCb experiment at centre-of-mass energies of 7, 8, and 13 TeV, corresponding to ...a total integrated luminosity of 9 fb
−
1
. The branching fraction of this decay is measured relative to the known branching fraction of the
B
+
→ ψ
(2
S
)
K
+
decay and found to be
B
B
+
→
Jψη
′
K
+
B
B
+
→
ψ
2
S
K
+
=
4.91
±
0.47
±
0.29
±
0.07
×
10
−
2
,
where the first uncertainty is statistical, the second is systematic and the third is related to external branching fractions. A first look at the
J/ψη
′ mass distribution is performed and no signal of intermediate resonances is observed.
Observation of the Ξb−→J/ψΛK− decay An, L.; Arnau Romeu, J.; Artamonov, A. ...
Physics letters. B,
09/2017, Letnik:
772, Številka:
C
Journal Article
Recenzirano
Odprti dostop
The observation of the decay Ξb−→J/ψΛK− is reported, using a data sample corresponding to an integrated luminosity of 3fb−1, collected by the LHCb detector in pp collisions at centre-of-mass energies ...of 7 and 8TeV. The production rate of Ξb− baryons detected in the decay Ξb−→J/ψΛK− is measured relative to that of Λb0 baryons using the decay Λb0→J/ψΛ. Integrated over the b-baryon transverse momentum pT<25GeV/c and rapidity 2.0<y<4.5, the measured ratio isfΞb−fΛb0B(Ξb−→J/ψΛK−)B(Λb0→J/ψΛ)=(4.19±0.29 (stat)±0.15 (syst))×10−2, where fΞb− and fΛb0 are the fragmentation fractions of b→Ξb− and b→Λb0 transitions, and B represents the branching fraction of the corresponding b-baryon decay. The mass difference between Ξb− and Λb0 baryons is measured to beM(Ξb−)−M(Λb0)=177.08±0.47 (stat)±0.16 (syst)MeV/c2.
The production of tt‾, W+bb‾ and W+cc‾ is studied in the forward region of proton–proton collisions collected at a centre-of-mass energy of 8 TeV by the LHCb experiment, corresponding to an ...integrated luminosity of 1.98±0.02 fb−1. The W bosons are reconstructed in the decays W→ℓν, where ℓ denotes muon or electron, while the b and c quarks are reconstructed as jets. All measured cross-sections are in agreement with next-to-leading-order Standard Model predictions.
Measurements of CP observables in B±→D(⁎)K± and B±→D(⁎)π± decays are presented, where D(⁎) indicates a neutral D or D⁎ meson that is an admixture of D(⁎)0 and D¯(⁎)0 states. Decays of the D⁎ meson to ...the Dπ0 and Dγ final states are partially reconstructed without inclusion of the neutral pion or photon, resulting in distinctive shapes in the B candidate invariant mass distribution. Decays of the D meson are fully reconstructed in the K±π∓, K+K− and π+π− final states. The analysis uses a sample of charged B mesons produced in pp collisions collected by the LHCb experiment, corresponding to an integrated luminosity of 2.0, 1.0 and 2.0 fb−1 taken at centre-of-mass energies of s=7, 8 and 13 TeV, respectively. The study of B±→D⁎K± and B±→D⁎π± decays using a partial reconstruction method is the first of its kind, while the measurement of B±→DK± and B±→Dπ± decays is an update of previous LHCb measurements. The B±→DK± results are the most precise to date.
Search for the decay B 0 → ϕμ + μ Aaij, R.; Eklund, Lars; Zunica, G.
The journal of high energy physics,
05/2022, Letnik:
2022, Številka:
5
Journal Article
Recenzirano
Odprti dostop
A search for the decay B-0 -> phi mu(+) mu(-) is performed using proton-proton collisions at centre-of-mass energies of 7, 8, and 13 TeV collected by the LHCb experiment and corresponding to an ...integrated luminosity of 9 fb(-1). No evidence for the B-0 -> phi mu(+) mu(-) decay is found and an upper limit on the branching fraction, excluding the 0 and charmonium regions in the dimuon spectrum, of 4.4 x 10(-3) at a 90% credibility level, relative to that of the B-s(0) -> phi mu(+) mu(-) decay, is established. Using the measured B-s(0) -> phi mu(+) mu(-) branching fraction and assuming a phase-space model, the absolute branching fraction of the decay B-0 -> phi mu(+) mu(-) in the full q(2) range is determined to be less than 3.2 x 10(-9) at a 90% credibility level.
A
bstract
The resonant structure of the doubly Cabibbo-suppressed decay
D
+
→
K
−
K
+
K
+
is studied for the first time. The measurement is based on a sample of
pp
-collision data, collected at a ...centre-of-mass energy of 8 TeV with the LHCb detector and corresponding to an integrated luminosity of 2 fb
−1
. The amplitude analysis of this decay is performed with the isobar model and a phenomenological model based on an effective chiral Lagrangian. In both models the S-wave component in the
K
−
K
+
system is dominant, with a small contribution of the
ϕ
(1020) meson and a negligible contribution from tensor resonances. The
K
+
K
−
scattering amplitudes for the considered combinations of spin (0,1) and isospin (0,1) of the two-body system are obtained from the Dalitz plot fit with the phenomenological decay amplitude.
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