A measurement of ∆Γs Agapopoulou, C.; Alessio, F.; Aliouche, Z. ...
The journal of high energy physics,
22/5, Letnik:
2024, Številka:
5
Journal Article
Recenzirano
Odprti dostop
A
bstract
Using a dataset corresponding to 9 fb
−
1
of integrated luminosity collected with the LHCb detector between 2011 and 2018 in proton-proton collisions, the decay-time distributions of the ...decay modes
B
s
0
→
J
/
ψη
′
and
B
s
0
→
J
/
ψ
π
+
π
−
are studied. The decay-width difference between the light and heavy mass eigenstates of the
B
s
0
meson is measured to be ∆Γ
s
= 0
.
087 ± 0
.
012 ± 0
.
009 ps
−
1
, where the first uncertainty is statistical and the second systematic.
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 search for rare B → Dμ+μ− decays Alessio, F.; Aliouche, Z.; Artamonov, A. ...
The journal of high energy physics,
02/2024, Letnik:
2024, Številka:
2
Journal Article
Recenzirano
Odprti dostop
A
bstract
A search for rare
B → Dμ
+
μ
−
decays is performed using proton-proton collision data collected by the LHCb experiment, corresponding to an integrated luminosity of 9 fb
−
1
. No ...significant signals are observed in the non-resonant
μ
+
μ
−
modes, and upper limits of
B
B
0
→
D
¯
0
μ
+
μ
−
<
5.1
×
10
−
8
,
B
B
+
→
D
s
+
μ
+
μ
−
<
3.2
×
10
−
8
,
B
B
s
0
→
D
¯
0
μ
+
μ
−
<
1.6
×
10
−
7
and
f
c
/
f
u
·
B
B
c
+
→
D
s
+
μ
+
μ
−
<
9.6
×
10
−
8
are set at the 95 % confidence level, where
f
c
and
f
u
are the fragmentation fractions of a
B
meson with a
c
and
u
quark respectively in proton-proton collisions. Each result is either the first such measurement or an improvement by three orders of magnitude on an existing limit. Separate upper limits are calculated when the muon pair originates from a
J/ψ → μ
+
μ
−
decay. The branching fraction of
B
c
+
→
D
s
+
J
/
ψ
multiplied by the fragmentation-fraction ratio is measured to be
f
c
f
u
·
B
B
c
+
→
D
s
+
J
/
ψ
=
1.63
±
0.15
±
0.13
×
10
−
5
,
where the first uncertainty is statistical and the second systematic.
A
bstract
An amplitude analysis of the
D
+
→ π
−
π
+
π
+
decay is performed with a sample corresponding to 1.5 fb
−
1
of integrated luminosity of
pp
collisions at a centre-of-mass energy
s
= 8 TeV ...collected by the LHCb detector in 2012. The sample contains approximately six hundred thousand candidates with a signal purity of 95%. The resonant structure is studied through a fit to the Dalitz plot where the
π
−
π
+
S-wave amplitude is extracted as a function of
π
−
π
+
mass, and spin-1 and spin-2 resonances are included coherently through an isobar model. The S-wave component is found to be dominant, followed by the
ρ
(770)
0
π
+
and
f
2
(1270)
π
+
components. A small contribution from the
ω
(782)
→ π
−
π
+
decay is seen for the first time in the
D
+
→ π
−
π
+
π
+
decay.
The first observation of the decay ηc(2S)→pp¯ is reported using proton–proton collision data corresponding to an integrated luminosity of 3.0 fb−1 recorded by the LHCb experiment at centre-of-mass ...energies of 7 and 8 TeV. The ηc(2S) resonance is produced in the decay B+→cc¯K+. The product of branching fractions normalised to that for the J/ψ intermediate state, Rηc(2S), is measured to beRηc(2S)≡B(B+→ηc(2S)K+)×B(ηc(2S)→pp¯)B(B+→J/ψK+)×B(J/ψ→pp¯)=(1.58±0.33±0.09)×10−2, where the first uncertainty is statistical and the second systematic. No signals for the decays B+→X(3872)(→pp¯)K+ and B+→ψ(3770)(→pp¯)K+ are seen, and the 95% confidence level upper limits on their relative branching ratios are found to be RX(3872)<0.25×10−2 and Rψ(3770)<0.10. In addition, the mass differences between the ηc(1S) and the J/ψ states, between the ηc(2S) and the ψ(2S) states, and the natural width of the ηc(1S) are measured asMJ/ψ−Mηc(1S)=110.2±0.5±0.9 MeV,Mψ(2S)−Mηc(2S)=52.5±1.7±0.6 MeV,Γηc(1S)=34.0±1.9±1.3 MeV.
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.
Using proton-proton collision data, corresponding to an integrated luminosity of 9 fb(-1) collected with the LHCb detector, seven decay modes of the B-C(+) meson into a J/psi or psi(2S) meson and ...three charged hadrons, kaons or pions, are studied. The decays B-C (+)-> (psi(2S) -> J/psi pi(+)pi(-))pi(+), B+C -> (psi(2S)pi(+)pi(-)pi(+), B+C -> J/psi K+pi(-)pi(+) and B+C -> J/K+K-K+ are observed for the first time, and evidence for the B-C (+)-> (psi(2S)K+K-pi(+), decay is found, where J/psi and psi(2S) mesons are reconstructed in their dimuon decay modes. The ratios of branching fractions between the different B-C(+) decays are reported as well as the fractions of the decays proceeding via intermediate resonances. The results largely support the factorisation approach used for a theoretical description of the studied decays.
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.
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