نتایج جستجو برای: ππ electron
تعداد نتایج: 309859 فیلتر نتایج به سال:
The σ meson in a nuclear medium through two pion photoproduction We present theoretical results for (γ, π 0 π 0) and (γ, π ± π 0) production on nucleons and nuclei in the kinematical region where the scalar isoscalar ππ amplitude is influenced by the σ pole. The final state interaction of the pions modified by the nuclear medium produces a spectacular shift of strength of the π 0 π 0 invariant ...
The scalar – isoscalar ππ phase shifts are analysed using a separable potential model of three coupled channels (ππ , KK and an effective 2π2π system). Model parameters are fitted to two sets of solutions obtained in a recent analysis of the CERN-Cracow-Munich measurements of the πp↑ → π πn reaction on a polarized target. A relatively narrow (90 – 180 MeV) scalar resonance f0(1400− 1460) is fou...
We have searched with the KLOE detector for the P and CP violating decay η → ππ in a sample of 1.55 × 10 η’s from the decay φ → ηγ of φ-mesons produced in ee annihilations at DAΦNE. No signal is found. We obtain the upper limit BR(η → ππ)< 1.3×10 at 90% confidence level.
The goal of the DIRAC experiment at CERN (PS212) is to measure the ππ atom lifetime with 10% precision. Such a measurement would yield a precision of 5% on the value of the S-wave ππ scattering lengths combination |a0 − a2|. Based on part of the collected data we present a first result on the lifetime, τ = [
The goal of the DIRAC experiment at CERN (PS212) is to measure the ππ atom lifetime with 10% precision. Such a measurement would yield a precision of 5% on the value of the S-wave ππ scattering lengths combination |a0 − a2|. Based on part of the collected data we present a first result on the lifetime, τ = [
The scalar – isoscalar ππ phase shifts are analysed using a separable potential model of three coupled channels (ππ , KK and an effective 2π2π system). Model parameters are fitted to two sets of solutions obtained in a recent analysis of the CERN-Cracow-Munich measurements of the πp↑ → π πn reaction on a polarized target. A relatively narrow (90 – 180 MeV) scalar resonance f0(1400− 1460) is fou...
The excited state dynamics of resorcinol (1,3-dihydroxybenzene) following UV excitation at a range of pump wavelengths, 278 ≥ λ ≥ 255 nm, have been investigated using a combination of time-resolved velocity map ion imaging and ultrafast time-resolved ion yield measurements coupled with complementary ab initio calculations. After excitation to the 1(1)ππ* state we extract a timescale, τ1, for ex...
From a re-analysis of ππ → ππ and ππ → KK̄ data, we found for ππ S-wave interaction below 2 GeV, σ(400), f0(980), f0(1500) and f0(1780) clearly show up. f0(1370) can be included with a very small branching ratio to ππ. f0(1300) and f0(1590) are not real resonances and are due to interference effects of above resonances. The σ(400) with a width about 700 MeV is mainly produced by t-channel exchan...
The photolyase enzyme absorbs blue light to repair damaged DNA through a cyclic electron transfer reaction. A description of the underlying mechanism has proven to be a challenging issue for both experimental and theoretical studies. In the present work, combined CASPT2//CASSCF/AMBER (QM/MM) calculations have been performed for damaged DNA in photolyase. A proton-coupled electron transfer (PCET...
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