共查询到20条相似文献,搜索用时 15 毫秒
1.
The possible mechanisms for anomalous decay Z0→l+l-γ are discussed. The mechanism with anomaious ZZY vertex is investipted indetail. It is pointed out that this vertex may appear via some effective Lagrangian which can be derived from an SU(2)×U (1) gauge invariant effective Lagrangian after the spontaneous symmetry breaking. The predictions based on this mechanism are consistent with recent experiments and can be verified experimentally. This mechanism is consistent with a composite model of Z0 with radius 10-15 cm. 相似文献
2.
M. Ablikim M. N. Achasov X. C. Ai O. Albayrak M. Albecht D. J. Ambrose A. Amoroso 《中国物理C(英文版)》2016,40(11):113001-113001
By analyzing 2.93 fb-1 data collected at the center-of-mass energy √s=3.773 GeV with the BESIII detector, we measure the absolute branching fraction of the semileptonic decay D+→K0e+ve to be B(D+→K0e+ve)=(8.59±0.14±0.21)% using K0→KS0→π0π0, where the first uncertainty is statistical and the second systematic. Our result is consistent with previous measurements within uncertainties.. 相似文献
3.
4.
We calculated the explicit analytic expressions for the electroweak radiative corrections to the differential cross sectione + e ?→γZ 0 to one-loop in the framework of the Glashow-Salam-Weinberg model. Special attention is payed to the dependence on the Higgs and top quark masses. 相似文献
5.
Radiative Z0 production in e+e? collisions is analyzed as a method of measuring the partial width of the Z0 for decay into neutrinos and thus determining if there exist low mass neutral leptons beyond the three now known (νe,νμ,ντ). The conditions for observing the final state are analyzed and background cross sections are determined. We conclude that the experiment is feasible and requires relatively modest apparatus. 相似文献
6.
7.
8.
9.
The analytic helicity amplitudes of Z → 3γ, γγ → γZ and γZ → γγ via W-loop and charged scalar-loop are presented. There is some difference between our results and those in Z. Phys. C60 (1993) 175 (E.W.N. Glover and A.G. Morgan) for Z → 3γ via W-loop and fermion-loop, which has different physical meanings. 相似文献
10.
11.
A 4+ → 0+ cross-over γ-ray decay in 204Pb has been detected. The branching ratio of this transition to the 4+ → 2+ → 0+ cascade has been measured to be (0.012 ± 0.002)%. 相似文献
12.
13.
The additional weak corrections at one-loop level to process H0 → W+W- in the two-fliggsdoublet model are calculated. The corrections from the extra Higgs sector depend strongly on the masses of Higgs sectors and the ratio of vacuum expectation values tanβ. It is shown that the general two-Higgs-doublet model admits flexibility in adjusting the one-loop corrections for the decay. In particular, for the heavy Ho boson the additional corrections imply a 5~14% reduction, when MHo < 1 TeV, due to relative light H1 mass and heavy H2, Φ masses which we used. 相似文献
14.
Expectations for constraints on extra Z bosons are derived for LEP2 and future linear e+e? colliders. For typical GUTs, a Z′ with MZ′ ≤ 3 to $6sqrt {s}$ may cause observable effects. The Z′ discovery limits are dominated by statistical errors. However, if a Z′ signal is observed, the discrimination between different models becomes much worse if systematic errors are taken into account. Discrimination between models is possible for $M_{Z^{?ime}} < 3sqrt {s}$. A determination of Z′ff couplings independently of models becomes attractive with future colliders. Anticipated bounds are determined. 相似文献
15.
16.
Department of Physics, Zhongshan University, Guangzhou, China 相似文献
17.
Guido Montagna Oreste Nicrosini Fulvio Piccinini 《Zeitschrift fur Physik C Particles and Fields》1997,76(1):45-51
A complete next-to-leading order calculation of the initial-state O (α) photonic corrections to hadron and lepton-pair production in e + e ?. collisions is presented. The impact of the next-to-leading order corrections on the twofermion cross section and forward-backward asymmetry is studied in detail for several event selections, with special emphasis on hard photon effects at LEP1.5 and LEP2 energies. It is shown that for typical realistic event selections, initial-state next-to-leading order corrections in the soft approximation can be safely extrapolated to energies above the Z 0 peak without significant loss of precision. 相似文献
18.
R. Budny 《Physics letters. [Part B]》1975,55(2):227-231
The predicted cross section for the reaction e+e?→e+e? is presented assuming one photon and W0 exchange. Pure W0 terms and the W0 width are included. 相似文献
19.
We derive a compact expression for the cross sectione + e ?→μ+μ?, containing a full treatment of the electromagnetic radiative corrections from both initial and final states. By using a formulation in terms of evolution equations, we obtain an expression for the cross-section to theO(α2) which includes soft and hard photons and resums to all orders dominant and non-dominant logarithmic contributions. Comparisons with previous results are made. 相似文献
20.
We use the method of color effective Hamiltonian to calculate the probability of color singlet string states at the large Nc limit. We show that a qq + ng system produced from e + e- annihilation is definitely in color singlet string states when Nc → ∞, i.e., color,singlet string states account for 100% of all possible color singlet states. This justifies the approximation that the hadronization mechanism of each color-neutral flow piece connecting two color-adjacent partons is assumed to be the same as an independent qq singlet system. 相似文献