نتایج جستجو برای: ππ interactions
تعداد نتایج: 389020 فیلتر نتایج به سال:
In benzophenone, intersystem crossing occurs efficiently between the S1(nπ*) state and the T1 state of dominant nπ* character, leading to excited triplet states after photoexcitation. The transition mechanism between S1(nπ*) and T1 is still a matter of debate, despite several experimental studies. Quantum mechanical calculations have been performed in order to assess the relative efficiencies o...
The techniques of lattice gauge theory offer the possibility of accurate, non-perturbative calculation of the masses and matrix elements predicted by low-energy QCD. Of particular interest are the properties of the K-meson system and the lowenergy, weak matrix elements that are required to understand Kaon decays, especially those which enter the K → ππ amplitudes which violate CP symmetry. Pres...
We use a nonpertubative approach which combines coupled channel Lippmann Schwinger equations with meson-meson potentials provided by the lowest order chiral Lagrangian. By means of one parameter, a cut off in the momentum of the loop integrals, which results of the order of 1 GeV, we obtain singularities in the S-wave amplitudes corresponding to the σ, f0 and a0 resonances. The ππ → ππ , ππ → K...
In the framework of heavy baryon chiral perturbation theory, we give the chiral expansion for the πN → ππN threshold amplitudes D1 and D2 to quadratic order in the pion mass. The theoretical results agree within one standard deviation with the empirical values. We also derive a relation between the two threshold amplitudes of the reaction πN → ππN and the ππ S–wave scattering lengths, a0 and a0...
Recent data from Belle show unusually large partial widths Υ(5S) → Υ(1S)ππ and Υ(5S) → Υ(2S)ππ. The Z(4430) narrow resonance also reported by Belle in ψπ spectrum has the properties expected of a c̄cud̄ charged isovector tetraquark T c̄c . The analogous state T b̄b in the bottom sector might mediate anomalously large cascade decays in the Upsilon system, Υ(mS) → T b̄b π → Υ(nS)ππ, with a tetraquark-...
Using 58 million J/ψ events taken with the BESII detector, a search for ηc CP violating decays into ππ and KK̄ has been performed. No clear ηc signal is observed, and upper limits for B(ηc → ππ) and B(ηc → KK̄) are given at the 90% confidence level, B(J/ψ → γηc) · B(ηc → π π) < 1.1 × 10, B(J/ψ → γηc) · B(ηc → π π) < 0.71 × 10, B(J/ψ → γηc) · B(ηc → K K) < 0.96 × 10 and B(J/ψ → γηc) ·B(ηc → K 0 SK...
The influence of strong and electroweak penguin amplitudes in B/B̄ → ππ is investigated in connection with the determination of the unitarity triangle angle α of the CKM matrix. A relation between the observable asymmetry, the angle α, and the penguin amplitude is established. A model calculation of the penguin amplitude shows that the CP asymmetry in B → ππ decays is only mildly influenced by t...
We have measured ππ and KK production in two-photon collisions using 87.7 fb of data collected with the Belle detector at the asymmetric energy ee collider KEKB. The cross sections are measured to high precision in the two-photon center-of-mass energy (W ) range between 2.4GeV < W < 4.1GeV and angular region |cos θ∗| < 0.6. The cross section ratio σ(γγ → KK)/σ(γγ → ππ) is measured to be 0.89 ± ...
We present fixed-t subtracted dispersion relations for Compton scattering off the nucleon at energies E γ ≤ 500 MeV, as a formalism to extract the nucleon polarizabilities with a minimum of model dependence. The subtracted dispersion integrals are mainly saturated by πN intermediate states in the s-channel γN → πN → γN and ππ intermediate states in the t-channel γγ → ππ → N ¯ N. For the subproc...
Studies on hadron interactions from lattice QCD are reviewed. The S-wave ππ scattering lengths of the I = 0 and I = 2 channels are extracted from various lattice determinations of low energy constants in N f = 2 chiral perturbation theory. The results agree with each other and agree also with other non-lattice estimates. Recently the P-wave ππ scattering phase shift for the I = 1 channel has be...
نمودار تعداد نتایج جستجو در هر سال
با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید