Measurements of CP asymmetries in charmless three-body decays of B-+/- mesons are reported using proton-proton collision data collected by the LHCb detector, corresponding to an integrated luminosity ...of 5.9 fb(-1). The previously observed CP asymmetry in B-+/- -> pi(K+K-)-K-+/- decays is confirmed, and CP asymmetries are observed with a significance of more than five standard deviations in the B-+/- -> pi(+/-)pi(+)pi and B-+/- -> (KK+K-)-K-+/- decays, while the CP asymmetry of B-+/- -> K-+/-pi(+)pi(-) decays is confirmed to be compatible with zero. The distributions of these asymmetries are also studied as a function of the three-body phase space and suggest contributions from rescattering and resonance interference processes. An indication of the presence of the decays B+ -> pi(+) chi(c0) (1P) in both B+ ->pi(+)pi(+)pi and B+ ->pi+K+K- decays is observed, as is CP violation involving these amplitudes.
Mesons comprising a beauty quark and strange quark can oscillate between particle (B-s(0)) and antiparticle (B-s(-0)) flavour eigenstates, with a frequency given by the mass difference between heavy ...and light mass eigenstates, Delta m(s). Here we present a measurement of Delta m(s) using B-s(0) -> D-s(-)pi(+) decays produced in proton-proton collisions collected with the LHCb detector at the Large Hadron Collider. The oscillation frequency is found to be Delta m(s) = 17.7683 +/- 0.0051 +/- 0.0032 ps(-1), where the first uncertainty is statistical and the second is systematic. This measurement improves on the current Delta m(s) precision by a factor of two. We combine this result with previous LHCb measurements to determine Delta m(s) = 17.7656 +/- 0.0057 ps(-1), which is the legacy measurement of the original LHCb detector.
Resonant contributions in B0 & RARR; over bar D0D+s & pi;- and B+ & RARR; D-D+s & pi;+ decays are determined with an amplitude analysis, which is performed both separately and ...simultaneously, where in the latter case isospin symmetry between the decays is assumed. The analysis is based on data collected by the LHCb detector in proton-proton collisions at center-of-mass energies of 7, 8, and 13 TeV. The full data sample corresponds to an integrated luminosity of 9 fb-1. A doubly charged spin-0 open-charm tetraquark candidate together with a neutral partner, both with masses near 2.9 GeV, are observed in the Ds & pi; decay channel.
A time-dependent analysis of the Bs0→ϕγ decay rate is performed to determine the CP -violating observables Sϕγ and Cϕγ and the mixing-induced observable AϕγΔ. The measurement is based on a sample of ...pp collision data recorded with the LHCb detector, corresponding to an integrated luminosity of 3 fb−1 at center-of-mass energies of 7 and 8 TeV. The measured values are Sϕγ=0.43±0.30±0.11, Cϕγ=0.11±0.29±0.11, and AϕγΔ=−0.67−0.41+0.37±0.17, where the first uncertainty is statistical and the second systematic. This is the first measurement of the observables S and C in radiative Bs0 decays. The results are consistent with the standard model predictions.
A
bstract
The differential cross-section of prompt inclusive production of long-lived charged particles in proton-proton collisions is measured using a data sample recorded by the LHCb experiment at ...a centre-of-mass energy of
s
= 13 TeV. The data sample, collected with an unbiased trigger, corresponds to an integrated luminosity of 5
.
4 nb
−
1
. The differential cross-section is measured as a function of transverse momentum and pseudorapidity in the ranges
p
T
∈ 80
,
10 000) MeV
/c
and
η
∈ 2
.
0
,
4
.
8) and is determined separately for positively and negatively charged particles. The results are compared with predictions from various hadronic-interaction models.
A search for C P violation in charmless three-body Ξb− → pK− K− decays is performed using p p collision data recorded with the LHCb detector, corresponding to integrated luminosities of 1 fb−1 at a ...center-of-mass energy √s = 7 TeV, 2 fb−1 at √s = 8 TeV and 2 fb−1 at √s = 13 TeV . A good description of the phase-space distribution is obtained with an amplitude model containing contributions from Σ ( 1385 ) , Λ ( 1405 ) , Λ ( 1520 ) , Λ ( 1670 ) , Σ ( 1775 ) and Σ ( 1915 ) resonances. The model allows for C P -violation effects, which are found to be consistent with zero. The branching fractions of Ξ − b → Σ ( 1385 ) K − , Ξ − b → Λ ( 1405 ) K − , Ξb− → Λ ( 1520 ) K−, Ξb− → Λ ( 1670 ) K−, Ξb− b → Σ ( 1775 ) K− and Ξb− → Σ (1915) K − decays are also reported. In addition, an upper limit is placed on the product of ratios of Ωb− and Ξb− fragmentation fractions and the Ωb− → p K− K− and Ξb− → p K− K− branching fractions.
A
bstract
The production cross-section of the
χ
c
1
(3872) state relative to the
ψ
(2
S
) meson is measured using proton-proton collision data collected with the LHCb experiment at centre-of-mass ...energies of
s
= 8 and 13 TeV, corresponding to integrated luminosities of 2.0 and 5.4 fb
−
1
, respectively. The two mesons are reconstructed in the
J/ψπ
+
π
−
final state. The ratios of the prompt and nonprompt
χ
c
1
(3872) to
ψ
(2
S
) production cross-sections are measured as a function of transverse momentum,
p
T
, and rapidity,
y
, of the
χ
c
1
(3872) and
ψ
(2
S
) states, in the kinematic range 4
< p
T
<
20 GeV/
c
and 2
.
0
< y <
4
.
5. The prompt ratio is found to increase with
p
T
, independently of
y
. For the prompt component, the double ratio of the
χ
c
1
(3872) and
ψ
(2
S
) production cross-sections between 13 and 8 TeV is observed to be consistent with unity, independent of
p
T
and centre-of-mass energy.
Search for the doubly charmed baryon Ξcc Alexander, M.; Alves, A. A.; Baryshnikov, F. ...
Science China. Physics, mechanics & astronomy,
02/2020, Letnik:
63, Številka:
2
Journal Article
Recenzirano
Odprti dostop
A search for the doubly charmed baryon
Ξ
c
c
+
is performed through its decay to the
Λ
c
+
K
−
π
+
final state, using proton-proton collision data collected with the LHCb detector at centre-of-mass ...energies of 7, 8 and 13 TeV. The data correspond to a total integrated luminosity of 9 fb
−1
. No significant signal is observed in the mass range from 3.4 to 3.8 GeV/
c
2
. Upper limits are set at 95% credibility level on the ratio of the
Ξ
c
c
+
production cross-section times the branching fraction to that of
Λ
c
+
and
Ξ
c
c
+
+
baryons. The limits are determined as functions of the
Ξ
c
c
+
mass for different lifetime hypotheses, in the rapidity range from 2.0 to 4.5 and the transverse momentum range from 4 to 15 GeV/
c
.
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