Two new algorithms for use in the analysis of Formula: see text collision are developed to identify the flavour of Formula: see text mesons at production using pions and protons from the ...hadronization process. The algorithms are optimized and calibrated on data, using Formula: see text decays from Formula: see text collision data collected by LHCb at centre-of-mass energies of 7 and 8 TeV . The tagging power of the new pion algorithm is 60% greater than the previously available one; the algorithm using protons to identify the flavour of a Formula: see text meson is the first of its kind.
The decays Formula: see text and Formula: see text are observed for the first time using a data sample corresponding to an integrated luminosity of 3.0 fbFormula: see text, collected by the LHCb ...experiment in proton-proton collisions at the centre-of-mass energies of 7 and 8Formula: see text. The branching fractions relative to that of Formula: see text are measured to be Formula: see textwhere the first uncertainties are statistical and the second are systematic.
A search for the rare decays
K
S
→
π
0
e
+
e
−
and
K
S
→
π
0
μ
+
μ
−
has been made by the NA48/1 experiment at the CERN SPS. The data were collected during 2002 in an 89 day run with a ...high-luminosity
K
S
beam. Seven
K
S
→
π
0
e
+
e
−
candidates have been observed with an expected background of 0.15 events. There were six
K
S
→
π
0
μ
+
μ
−
candidates observed with an expected background of
0.22
−0.11
+0.18
events. The measured branching ratios are
BR
(
K
S
→
π
0
e
+
e
−
,
m
e
e
>
0.165
GeV
/
c
2
)
=
(
3.0
−1.2
+1.5
stat
±
0.2
syst
)
×
10
−9
and
BR
(
K
S
→
π
0
μ
+
μ
−
)
=
(
2.8
−1.2
+1.5
stat
±
0.2
syst
)
×
10
−9
These results are used to test Chiral Perturbation Theory and to estimate the CP violating component of the corresponding
K
L
decays.
NA48/2 results contributing to ChPT testing are presented. A sample of 1663 events of the rare decay $ K^ \pm \to \mu ^ \pm ve^ + e^ - $ has been selected with a minimum
e
+
e
−
effective mass of 140 ...MeV. The measured model independent decay rate is in agreement with ChPT predictions. The branching ratio of the $ K^ \pm \to \mu ^ \pm ve^ + e^ - $ decay, never observed so far, has been obtained from a sample of about 5000 candidates with less than 6% background, also in agreement with ChPT predictions. In addition, a most precise measurement of the charged kaon semileptonic formfactors has been obtained from 4.4 million
K
e3
and 2.3 million
K
µ3
events collected in 2004.
From the 2002 data taking with a neutral kaon beam extracted from the CERN-SPS, the NA48/1 experiment observed 97 Ξ0→Σ+μ−ν¯μ candidates with a background contamination of 30.8±4.2 events. From this ...sample, the BR(Ξ0→Σ+μ−ν¯μ) is measured to be (2.17±0.32stat±0.17syst)×10−6.
(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image) Abstract A test of lepton universality, performed by measuring the ratio of the branching fractions of the B 0 rarr K *0 mu ...+ mu - and B 0 rarr K *0 e + e - decays, ..., is presented. The K *0 meson is reconstructed in the final state K + pi -, which is required to have an invariant mass within 100 MeV/c 2 of the known K *(892)0 mass. The analysis is performed using proton-proton collision data, corresponding to an integrated luminosity of about 3 fb-1, collected by the LHCb experiment at centre-of-mass energies of 7 and 8 TeV. The ratio is measured in two regions of the dilepton invariant mass squared, q 2, to be ... The corresponding 95.4% confidence level intervals are 0.52, 0.89 and 0.53, 0.94. The results, which represent the most precise measurements of ... to date, are compatible with the Standard Model expectations at the level of 2.1-2.3 and 2.4-2.5 standard deviations in the two q 2 regions, respectively. Figure not available: see fulltext.
(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image) The decays of B s 0 and ... mesons into the J/ψK + K − final state are studied in the K + K − mass region above the ϕ(1020) ...meson in order to determine the resonant substructure and measure the CP-violating phase, ϕ s , the decay width, Γ s , and the width difference between light and heavy mass eigenstates, ΔΓ s . A decay-time dependent amplitude analysis is employed. The data sample corresponds to an integrated luminosity of 3 fb−1 produced in 7 and 8 TeV pp collisions at the LHC, collected by the LHCb experiment. The measurement determines ϕ s = 119 ± 107 ± 34 mrad. A combination with previous LHCb measurements using similar decays into the J/ψπ + π − and J/ψϕ(1020) final states gives ϕ s = 1 ± 37 mrad, consistent with the Standard Model prediction. Figure not available: see fulltext.
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