分类: 物理学 >> 基本粒子与场物理学 提交时间: 2016-05-09
摘要: Motivated by the future precision test of the Higgs boson at an e(+)e(-) Higgs factory, we calculate the production e(+)e(-) -> ZH gamma in the Standard Model with complete next-to-leading order electroweak corrections. We find that for p s root s = 240 (350) GeV the cross section of this production is sizably reduced by the electroweak corrections, which is 1.03 (5.32) fb at leading order and 0.72 (4.79) fb at next-to-leading order. The transverse momentum distribution of the photon in the final states is also presented.
分类: 物理学 >> 基本粒子与场物理学 提交时间: 2016-05-09
摘要: We attempt to explain the recent ATLAS 3 sigma excess of dilepton events with an invariant mass near Z peak through the gluino-mediated sbottom production in a simplified scenario inspired by the minimal supersymmetric Standard Model. The additional Z bosons can be produced through the cascade decay chain (g) over tilde -> b (b) over tilde1(dagger) -> b (b) over bar(chi) over tilde (0)(2,3) -> b (b) over bar(chi) over tilde (0)(1)Z, in which (b) over tilde (1) is the right-handed sbottom, (chi) over tilde (0)(1) is the bino-like lightest supersymmetric particle (LSP) and (chi) over tilde (0)(2,3) are two nearly degenerate Higgsino-like next-to LSPs. Taking into account the constraint from the LHC search for the gluino-mediated sbottom production in the final states with the missing transverse energy and at least three b-jets, we find that the ATLAS on-Z excess can only be marginally explained at the 2 sigma level. We also note that within the scenario where the gluino predominantly decays to the right-handed stop instead of the sbottom, the excess can hardly be explained, since the Z-boson is not produced in the stop dominant decay channel, (t) over tilde (1) -> b (chi) over tilde (+)(1).