نتایج جستجو برای: ππ electron
تعداد نتایج: 309859 فیلتر نتایج به سال:
We report the results from a study of the full sample of ∼ 6.031 × 10 K → πππ decays recorded by the NA48/2 experiment at the CERN SPS. As first observed in this experiment, the ππ invariant mass (M00) distribution shows a cusp-like anomaly in the region around M00 = 2m+, where m+ is the charged pion mass. This anomaly has been interpreted as an effect due mainly to the final state charge excha...
A numerical analysis to the scalar form-factor in the ππ and KK coupled–channel system is made by solving the coupled-channel dispersive integral equations, using the iteration method. The solutions are found not unique. Physical application to the ππ central production in the pp → ppππ process is discussed based upon the numerical solutions we found. PACS numbers: 14.40.Aq; 11.55.Fv; 13.75.Lb ...
We present a measurement of the branching ratio of the CP violating decay KL→ ππ performed by the KLOE experiment at the φ factory DAΦNE. We use 328 pb of data collected in 2001 and 2002, corresponding to ∼ 150 million tagged KL mesons. We find BR(KL → ππ) = (1.963 ± 0.012stat. ± 0.017syst.) × 10. This branching ratio measurement is fully inclusive of final-state radiation. Using the above resu...
We perform a detailed Regge analysis of NN , πN and ππ scattering. From it, we find expressions that represent the ππ scattering amplitudes with an accuracy of a few percent, for exchange of isospin zero, and ∼ 15% for exchange of isospin 1, and this for energies s > 1.4GeV and for momentum transfers |t| < ∼ 0.4GeV. These Regge formulas are perfectly compatible with the low energy (s ∼ 1.4GeV) ...
A numerical analysis to the scalar form-factor in the ππ and KK coupled–channel system is made by solving the coupled-channel dispersive integral equations, using the iteration method. The solutions are found not unique. Physical application to the ππ central production in the pp → ppππ process is discussed based upon the numerical solutions we found. PACS numbers: 14.40.Aq; 11.55.Fv; 13.75.Lb ...
Low energy parameters of the KK and ππ scalar-isoscalar interactions Abstract Threshold expansions of the ππ and KK spin 0 and isospin 0 scattering amplitudes are performed. Scattering lengths, effective ranges and so–called volume parameters are evaluated. Good agreement with the existing experimental data for the ππ scalar–isoscalar amplitude is found. An importance of future accurate measure...
The phase variation of the σ → ππ amplitude is accurately determined as a function of mass from BES II data for J/Ψ → ωπ + π −. The determination arises from interference with the strong b 1 (1235)π amplitude. The observed phase variation agrees within errors with that in ππ elastic scattering. The σ pole appears as a conspicuous π + π − peak in BES II data for J/Ψ → ωπ + π − [1]. This peak is ...
The Schrödinger equation discribing the local potential model of a strong ππ-interaction was studied. The influence of the strong ππ-interaction of the behaviour of pionium nS-state wave functions at small distances is studied both analytically (perturbatively) and numerically. It is shown that in the whole the accounting of strong interaction results in multiplying pure Coulomb pionium wave fu...
The excited state lifetimes of DNA bases are often very short due to very efficient non-radiative processes assigned to the ππ*-nπ* coupling. A set of protonated aromatic diazine molecules (pyridazine, pyrimidine and pyrazine C4H5N2(+)) and protonated pyrimidine DNA bases (cytosine, uracil and thymine), as well as the protonated pyridine (C5H6N(+)), have been investigated. For all these molecul...
An elementary derivation is given of Cabibbo’s formula for subthreshold ππ charge-exchange (cx) interference in the three-meson final states produced in certain meson decays. The relative phase between the two interfering decay amplitudes from the ππ and ππ channels is found to depend almost entirely on the ClebschGordan coefficients appearing in the dominant isospin component of the final stat...
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