193 research outputs found
Study of decays to the final state and evidence for the decay
A study of decays is performed for the first time
using data corresponding to an integrated luminosity of 3.0
collected by the LHCb experiment in collisions at centre-of-mass energies
of and TeV. Evidence for the decay
is reported with a significance of 4.0 standard deviations, resulting in the
measurement of
to
be .
Here denotes a branching fraction while and
are the production cross-sections for and mesons.
An indication of weak annihilation is found for the region
, with a significance of
2.4 standard deviations.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2016-022.html,
link to supplemental material inserted in the reference
Measurement of D s <sup>±</sup> production asymmetry in pp collisions at âs=7 and 8 TeV
The inclusive production asymmetry is measured in collisions
collected by the LHCb experiment at centre-of-mass energies of
and 8 TeV. Promptly produced mesons are used, which decay as
, with . The measurement is
performed in bins of transverse momentum, , and rapidity, ,
covering the range GeV and . No kinematic
dependence is observed. Evidence of nonzero production asymmetry is
found with a significance of 3.3 standard deviations.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2018-010.htm
Observation of B(s)0âJ/ÏppÂŻ decays and precision measurements of the B(s)0 masses
The first observation of the decays
B
0
(
s
)
â
J
/
Ï
p
ÂŻ
p
is reported, using proton-proton collision data corresponding to an integrated luminosity of
5.2
â
â
fb
â
1
, collected with the LHCb detector. These decays are suppressed due to limited available phase space, as well as due to Okubo-Zweig-Iizuka or Cabibbo suppression. The measured branching fractions are
B
(
B
0
â
J
/
Ï
p
ÂŻ
p
)
=
[
4.51
±
0.40
(
stat
)
±
0.44
(
syst
)
]
Ă
10
â
7
,
B
(
B
0
s
â
J
/
Ï
p
ÂŻ
p
)
=
[
3.58
±
0.19
(
stat
)
±
0.39
(
syst
)
]
Ă
10
â
6
. For the
B
0
s
meson, the result is much higher than the expected value of
O
(
10
â
9
)
. The small available phase space in these decays also allows for the most precise single measurement of both the
B
0
mass as
5279.74
±
0.30
(
stat
)
±
0.10
(
syst
)
â
â
MeV
and the
B
0
s
mass as
5366.85
±
0.19
(
stat
)
±
0.13
(
syst
)
â
â
MeV
Observation of the decay Î <sub>b</sub> <sup>0</sup> âââÏ(2S)pÏ<sup>â</sup>
International audienceThe Cabibbo-suppressed decay Î âââÏ(2S)pÏ is observed for the first time using a data sample collected by the LHCb experiment in proton-proton collisions corresponding to 1.0, 2.0 and 1.9 fb of integrated luminosity at centre-of-mass energies of 7, 8 and 13 TeV, respectively. The Ï(2S) mesons are reconstructed in the ΌΌ final state. The branching fraction with respect to that of the Î âââÏ(2S)pK decay mode is measured to b
Precision measurement of violation in the penguin-mediated decay
A flavor-tagged time-dependent angular analysis of the decay
is performed using collision data collected
by the LHCb experiment at % at TeV, the center-of-mass energy of
13 TeV, corresponding to an integrated luminosity of 6 fb^{-1}. The
-violating phase and direct -violation parameter are measured
to be rad and
, respectively, assuming the same values
for all polarization states of the system. In these results, the
first uncertainties are statistical and the second systematic. These parameters
are also determined separately for each polarization state, showing no evidence
for polarization dependence. The results are combined with previous LHCb
measurements using collisions at center-of-mass energies of 7 and 8 TeV,
yielding rad and . This is the most precise study of time-dependent violation
in a penguin-dominated meson decay. The results are consistent with
symmetry and with the Standard Model predictions.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2023-001.html (LHCb
public pages
Search for CP violation in Îb0âpKâ and Îb0âpÏâ decays
A search for CP violation in Îb0âpKâ and Îb0âpÏâ decays is presented using a sample of pp collisions collected with the LHCb detector and corresponding to an integrated luminosity of 3.0fbâ1. The CP -violating asymmetries are measured to be ACPpKâ=â0.020±0.013±0.019 and ACPpÏâ=â0.035±0.017±0.020, and their difference ACPpKââACPpÏâ=0.014±0.022±0.010, where the first uncertainties are statistical and the second systematic. These are the most precise measurements of such asymmetries to date
Observation of a resonant structure near the threshold in the decay
An amplitude analysis of the decay is carried out to
study for the first time its intermediate resonant contributions, using
proton-proton collision data collected with the LHCb detector at centre-of-mass
energies of 7, 8 and 13 TeV. A near-threshold peaking structure, referred to as
, is observed in the invariant-mass spectrum with
significance greater than 12 standard deviations. The mass, width and the
quantum numbers of the structure are measured to be MeV,
MeV and , respectively, where the first
uncertainties are statistical and the second systematic. The properties of the
new structure are consistent with recent theoretical predictions for a state
composed of quarks. Evidence for an additional structure is
found around 4140 MeV in the invariant mass, which might be
caused either by a new resonance with the assignment or by a coupled-channel effect.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-018.html (LHCb
public pages
Evidence for an nc(1S)ff- resonance in B0 yc(1S)K+ decays
A Dalitz plot analysis of B0âηc(1S)K+Ï- decays is performed using data samples of pp collisions collected with the LHCb detector at centre-of-mass energies of s=7,8 and 13TeV , corresponding to a total integrated luminosity of 4.7fb-1 . A satisfactory description of the data is obtained when including a contribution representing an exotic ηc(1S)Ï- resonant state. The significance of this exotic resonance is more than three standard deviations, while its mass and width are 4096±20-22+18MeV and 152±58-35+60MeV , respectively. The spin-parity assignments JP=0+ and JP=1- are both consistent with the data. In addition, the first measurement of the B0âηc(1S)K+Ï- branching fraction is performed and gives B(B0âηc(1S)K+Ï-)=(5.73±0.24±0.13±0.66)Ă10-4, where the first uncertainty is statistical, the second systematic, and the third is due to limited knowledge of external branching fractions
Measurement of the B0s âJ/Ïη lifetime
Using a data set corresponding to an integrated luminosity of 3 fbâ1, collected by the LHCb experiment in pp collisions at centre-of-mass energies of 7 and 8 TeV, the effective lifetime in the Bs0âJ/Ïη decay mode, Ïeff, is measured to be
Ïeff=1.479±0.034 (stat)±0.011 (syst) ps. Assuming CP conservation, Ïeff corresponds to the lifetime of the light Bs0 mass eigenstate. This is the first measurement of the effective lifetime in this decay mode
Test of lepton universality in decays
The first simultaneous test of muon-electron universality using
and decays is performed, in two ranges of the dilepton
invariant-mass squared, . The analysis uses beauty mesons produced in
proton-proton collisions collected with the LHCb detector between 2011 and
2018, corresponding to an integrated luminosity of 9 . Each
of the four lepton universality measurements reported is either the first in
the given interval or supersedes previous LHCb measurements. The
results are compatible with the predictions of the Standard Model.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-046.html (LHCb
public pages
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