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Rubin, P.

Publications and source records attributed to Rubin, P..

15 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

First observation and study of the $K^± → π^0π^0μ^±ν$ decay

The NA48/2 experiment at CERN reports the first observation of the $K^± → π^0π^0μ^±$ν decay based on a sample of 2437 candidates with 15% background contamination collected in 2003–2004. The decay branching ratio in the kinematic region of the squared dilepton mass above 0.03 GeV 2 /c 4 is measured to be (0.65 ± 0.03) × 10 –6 . The extrapolation to the full kinematic space, using a specific model, is found to be (3.45 ± 0.16) × 10 –6 , in agreement with chiral perturbation theory predictions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

First observation and study of the K ± →π ± π 0 e + e - decay

The NA48/2 experiment at CERN reports the first observation of the ± →π ± π 0 e + e - decay from an exposure of 1.7 x 10 11 charged kaon decays recorded in 2003–2004. A sample of 4919 candidates with 4.9% background contamination allows the determination of the branching ratio in the full kinematic region, BR (K ± → π ± π 0 e + e - = (4.24 ± 0.14) x 10 -6 . Finally the study of the kinematic space shows evidence for a structure dependent contribution in agreement with predictions based on chiral perturbation theory. Several P- and CP-violating asymmetries are also evaluated.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2018

Measurement of the form factors of charged kaon semileptonic decays

A measurement of the form factors of charged kaon semileptonic decays is presented, based on 4.4 × 10 6K± → π 0 e ± ν e (K e 3 ± ) and 2.3 × 10 6 K ± → π 0 μ±ν μ (K μ 3 ±) decays collected in 2004 by the NA48/2 experiment. The results are obtained with improved precision as compared to earlier measurements. The combination of measurements in the K e3 ± and K μ3 ± modes is also presented.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Searches for lepton number violation and resonances in K ± → πμμ decays

The NA48/2 experiment at CERN collected a large sample of charged kaon decays to final states with multiple charged particles in 2003$-$2004. A new upper limit on the rate of the lepton number violating decay $K^{\pm}\to\pi^{\mp}\mu^{\pm}\mu^{\pm}$ is reported: $\mathcal{B}(K^{\pm}\to\pi^{\mp}\mu^{\pm}\mu^{\pm})<8.6 \times 10^{-11}$ at 90% CL. Searches for two-body resonances $X$ in $K^{\pm}\to\pi\mu\mu$ decays (such as heavy neutral leptons $N_4$ and inflatons $\chi$) are also presented. Finally, in the absence of signals, upper limits are set on the products of branching fractions $\mathcal{B}(K^{\pm}\to\mu^{\pm}N_4)\mathcal{B}(N_4\to\pi\mu)$ and $\mathcal{B}(K^{\pm}\to\pi^{\pm}X)\mathcal{B}(X\to\mu^+\mu^-)$ for ranges of assumed resonance masses and lifetimes. The limits are in the $(10^{-11},10^{-9})$ range for resonance lifetimes below 100 ps.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Precision measurement of the ratio of the charged kaon leptonic decay rates

A precision measurement of the ratio RK of the rates of kaon leptonic decays K+- --> e nu and K+- --> mu nu with the full data sample collected by the NA62 experiment at CERN in 2007-2008 is reported. The result, obtained by analysing ~150000 reconstructed K+- --> e nu candidates with 11% background contamination, is RK = (2.488+-0.010)*10^{-5}, in agreement with the Standard Model expectation.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Amplitude analyses of the decays χ c1 →ηπ⁺π⁻ and χ c1 →η'π⁺π⁻

Using a data sample of 2.59×10⁷ ψ(2S) decays obtained with the CLEO-c detector, we perform amplitude analyses of the complementary decay chains ψ(2S)→γχ c1 ; χ c1 →ηπ⁺π⁻ and ψ(2S)→γχ c1 ; χ c1 →η'π⁺π⁻. We find evidence for an exotic P-wave η'π amplitude, which, if interpreted as a resonance, would have parameters consistent with the π₁(1600) state reported in other production mechanisms. We also make the first observation of the decay a₀(980)→η'π and measure the ratio of branching fractions B(a₀(980)→η'π)/B(a₀(980)→ηπ)=0.064±0.014±0.014. The ππ spectrum produced with a recoiling η is compared to that with η' recoil.

Adams, G. S.↗
DOE OSTI2011

Studies of D⁺→{η',η,Φ}e⁺ν e

We report the first observation of the decay D⁺→η'e⁺ν e in two analyses, which combined provide a branching fraction of B(D⁺→η'e⁺ν e )=(2.16±0.53±0.07)×10⁻⁴. We also provide an improved measurement of B(D⁺→ηe⁺ν e )=(11.4±0.9±0.4)×10⁻⁴, provide the first form factor measurement, and set the improved upper limit B(D⁺→Φe⁺ν e )<0.9×10⁻⁴ (90%C.L.).

Yelton, J.↗