We present a precise measurement of the ratio RK=Γ(K→eν(γ))/Γ(K→μν(γ)) and a study of the radiative process K→eνγ, performed with the KLOE detector. The results are based on data collected at the ...Frascati e+e− collider DAΦNE for an integrated luminosity of 2.2 fb−1. We find RK=(2.493±0.025stat±0.019syst)×10−5, in agreement with the Standard Model expectation. This result is used to improve constraints on parameters of the Minimal Supersymmetric Standard Model with lepton flavor violation. We also measured the differential decay rate dΓ(K→eνγ)/dEγ for photon energies 10<Eγ< 250 MeV. Results are compared with predictions from theory.
The KLOE electromagnetic calorimeter Adinolfi, M; Ambrosino, F; Antonelli, A ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2002, Letnik:
482, Številka:
1-2
Journal Article
Recenzirano
The KLOE detector was designed primarily for the study of CP violation in neutral kaon decays at DAΦNE, the Frascati φ-factory. The detector consists of a tracker and an electromagnetic calorimeter. ...A lead-scintillating-fiber sampling calorimeter satisfies best the requirements of the experiment, providing adequate energy resolution and superior timing accuracy. We describe in the following the construction of the calorimeter, its calibration and how the calorimeter information is used to obtain energy, point of entry and time of the arrival of photons, electrons and charged particles. With e+e− collision data at DAΦNE for an integrated luminosity of some 2pb−1 we find for electromagnetic showers, an energy resolution of 5.7%/E(GeV) and a time resolution of 54/E(GeV) ps. We also present a measurement of efficiency for low energy photons.
We have studied the η→π+π−e+e−(γ) decay using about 1.7 fb−1 collected by the KLOE experiment at the DAΦNE ϕ-factory. This corresponds to about 72 millions η mesons produced in ϕ radiative decays. We ...have measured the branching ratio, inclusive of radiative effects, with 4% accuracy: BR(η→π+π−e+e−(γ))=(26.8±0.9Stat.±0.7Syst.)×10−5. We have obtained the first measurement of the CP-odd ππ–ee decay planes angular asymmetry, Aϕ=(−0.6±2.5Stat.±1.8Syst.)×10−2.
ObjectivesTo evaluate in a multicentric Italian cohort of patients with psoriatic arthritis (PsA) on secukinumab followed for 24 months: (1) the long-term effectiveness and safety of secukinumab, (2) ...the drug retention rate and minimal disease activity (MDA), (3) differences in the outcomes according to the biological treatment line: biologic-naïve patients (group A) versus multifailure (group B) patients.MethodsConsecutive patients with PsA receiving secukinumab were evaluated prospectively. Disease characteristics, previous/ongoing treatments, comorbidities and follow-up duration were collected. Disease activity/functional/clinimetric scores and biochemical values were recorded at baseline (T0), 6(T6), 12(T12) and 24(T24) months. Effectiveness was evaluated overtime with descriptive statistics; multivariate Cox and logistic regression models were used to evaluate predictors of drug-discontinuation and MDA at T6. Infections and adverse events were recorded.Results608 patients (41.28% men; mean (SD) age 52.78 (11.33)) were enrolled; secukinumab was prescribed as first-line biological treatment in 227 (37.34%) patients, as second (or more)-line biological treatment in 381 (62.66%). Effectiveness of secukinumab was shown with an improvement in several outcomes, such as Ankylosing Spondylitis Disease Activity Score (T0=3.26 (0.88) vs T24=1.60 (0.69) ;p=0.02) and Disease Activity Index for Psoriatic Arthritis (T0=25.29 (11.14) vs T24=7.69 (4.51); p<0.01). At T24, group A showed lower Psoriasis Area Severity Index (p=0.04), erythrocyte sedimentation rate and C reactive protein (p=0.03 ;p=0.05) and joint count (p=0.03) compared with group B. At T24, MDA was achieved in 75.71% of group A and 70.37% of group B. Treatment was discontinued in 123 (20.23%) patients, mainly due to primary/secondary loss of effectiveness, and in 22 due to adverse events. Retention rate at T24 was 71% in the whole population, with some difference depending on secukinumab dosage (p=0.004) and gender (p=0.05).ConclusionsIn a real-life clinical setting, secukimumab proved safe and effective in all PsA domains, with notable drug retention rate.
We present a measurement of the K–π vector current form-factor parameters for the decay KL→π±e∓ν. We use 328 pb−1 of data collected in 2001 and 2002, corresponding to ∼2 million Ke3 events. ...Measurements of semileptonic form factors provide information about the dynamics of the strong interaction and are necessary for evaluation of the phase-space integral IKe needed to measure the CKM matrix element |Vus| for KL→π±e∓ν decays. Our result is λ+=(28.6±0.5±0.4)×10−3 for a linear fit, and λ+′=(25.5±1.5±1.0)×10−3, λ+″=(1.4±0.7±0.4)×10−3 for a quadratic fit.
We measured, with the KLOE detector, the spectrum of π+π− invariant mass in a sample of 6.7×105e+e−→π+π−γ events with the photon at large polar angle (θγ>45°) at a centre of mass energy s around the ...ϕ mass. We observe in this spectrum a clear contribution from the intermediate process ϕ→ f0(980)γ. A sizeable effect is also observed in the distribution of the pion forward–backward asymmetry. We use different theoretical models to fit the spectrum and we determine the f0 mass and coupling constants to the ϕ, to π+π− and to KK¯.
We present a measurement of the slope parameter a for the eta-->3pi super(0) decay, with the KLOE experiment at the DAPhiNE inline image-factory, based on a background free sample of inline image17 ...million eta mesons produced in inline image radiative decays. By fitting the event density in the Dalitz plot we determine inline image. The result is in agreement with recent measurements from hadro- and photo-production experiments.
We have measured the fully inclusive K+→μ+ν(γ) absolute branching ratio with the KLOE experiment at DAΦNE, the Frascati ϕ-factory. From some 865 283 K+→μ+ν(γ) decays obtained from a sample of ...∼5.2×108, ϕ-meson decays, we find BR(K+→μ+νμ(γ))=0.6366±0.0009stat.±0.0015syst., corresponding to an overall fractional error of 0.27%. Using recent lattice results on the decay constants of pseudoscalar mesons one can obtain an estimate for the CKM mixing matrix element |Vus|=0.2223±0.0026.
Using a large sample of pure, slow, short lived
K
0
mesons collected with KLOE detector at DAΦNE, we have measured the
K
S
lifetime. From a fit to the proper time distribution we find
τ
(
K
S
...)=(89.562±0.029
stat
±0.043
syst
) ps. This is the most precise measurement to date of the short lived
K
0
meson lifetime, in good agreement with the world average derived from previous measurements. We observe no dependence of the lifetime on the direction of the
K
S
in galactic coordinates.
The PADME collaboration aims to search for signals of a light dark photon
A′
using the beam of the LNF LINAC. The experiment, approved by INFN at the end of 2015, foresees to detect
A′
, produced in ...the annihilation of positrons on a thin fixed target, by searching for missing mass signals. The detector construction is ongoing and should be completed within the end of 2017 in order to allow the collection of about 10
13
positrons on target which are necessary to get a 10
−3
sensitivity on the mixing parameter
ε
up to a dark photon mass of 23.7 MeV/
c
2
.
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