نتایج جستجو برای: ππ electron
تعداد نتایج: 309859 فیلتر نتایج به سال:
The kaon bag parameter BK , which is required for constraining the CP violation parameter in the Cabibbo-Kobayashi-Maskawa matrix from experiment, has been successfully calculated with the Kogut-Susskind(KS) quark action, taking advantage of its UA(1) chiral symmetry[1]. A recent systematic calculation of BK with high statistics[2], however, reveals that the systematic uncertainties in the pert...
Decay rates of B(t) → ππ, B → πK, B → πK (KS → π π) and of charge-conjugate processes are studied within flavor SU(3) symmetry and first-order SU(3) breaking. We show that these measurements can determine with a reasonable accuracy the two angles, α and γ, of the CabibboKobayashi-Maskawa unitarity triangle. B decays provide a variety of CP asymmetry measurements [1], which can test the currentl...
Chiral nonperturbative approach to the isoscalar s-wave ππ interaction in a nuclear medium Abstract The s-wave isoscalar amplitude for ππ scattering in a nuclear medium is evaluated using a nonperturbative unitary coupled channels method and the standard chiral Lagrangians. The method has proved successful to describe the ππ properties in the scalar isoscalar channel up to 1.2 GeV giving rise t...
Recent measurements of the CP -violating asymmetry parameter sin2β by the BABAR [1] and BELLE [2] collaborations established CP violation in the B system. These measurements, as well as updated preliminary results [3, 4], are consistent with the Standard Model expectation based on measurements and theoretical estimates of the elements of the Cabibbo-Kobayashi-Maskawa [5] (CKM) quark-mixing matr...
Using the large hadroproduced charm sample collected in experiment E791 at Fermilab, we have measured ratios of branching fractions for the two-body singlyCabibbo-suppressed charged decays of the D: Γ(D → KK) Γ(D → Kπ) = 0.109± 0.003± 0.003, Γ(D → ππ) Γ(D → Kπ) = 0.040 ± 0.002 ± 0.003, and Γ(D → KK) Γ(D → ππ) = 2.75 ± 0.15±0.16. We have looked for differences in the decay rates of D andD to the...
We consider the ππ scattering amplitude obtained by Colangelo, Gasser and Leutwyler (CGL), using dispersion relations and chiral perturbation theory to two loops. We point out that the input used by CGL for energies above 1.42 GeV is incompatible with a number of experimental results. Moreover, the error they adscribe to the δ (0) 0 phase at 0.8 GeV, an important part of their input, is much un...
K → ππ, KL-KS mass difference and KL → γγ(∗) are studied systematically by decomposing their amplitude into a sum of factorizable and nonfactorizable ones. The former is calculated by using the naive factorization while the latter is assumed to be dominated by dynamical contributions of various hadron states. Non-factorizable amplitudes for the K → ππ decays are estimated by using a hard pion a...
We improve, in the energy region between K̄K threshold and ∼ 1.4 GeV, the energy-dependent phase shift analysis of ππ scattering presented in a previous paper. For the S0 wave we have included more data above K̄K threshold and we have taken into account systematically the elasticity data on the reaction ππ → K̄K. We here made a coupled channel fit. For the D0 wave we have considered information on...
It is important to understand charmless three-body B decays to probe the standard model. These decays are sensitive to CP violation and supply information on strong interactions. To interpret in a reliable way weak decay observables it is important to take into account final state interactions between produced meson pairs. In the weak decays B → ππK [ 1, 2] one sees maxima around the ππ effecti...
We investigate allowed regions in observable space of B → πK, Bd → ππ and Bs → KK decays, characterizing these modes in the Standard Model. After a discussion of a new kind of contour plots for the B → πK system, we focus on the mixing-induced and direct CP asymmetries of the decays Bd → ππ and Bs → KK. Using experimental information on the CP-averaged Bd → πK and Bd → ππ branching ratios, the ...
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