We report on a calculation of the effects of supersymmetry on the cross-section for top-antitop production at LHC. A numerical study is carried out for the ten benchmarks of the Snowmass accord. It is found that the higher order effects involving supersymmetric particles in internal loops can be as high as 6%, both for the cross-section and the (parity even) helicity asymmetry, for one particular benchmark. For other benchmarks smaller but nonetheless observable corrections are found.
A brief summary of the calculation of the NLO QCD corrections to the process pp -> e+ ve mu- v_mu bb~ j + X is reported. This provides a complete description of the process of t-tbar + jet production with leptonic decays beyond the narrow-width approximation. Off-shell effects for top quarks and W boson decays are fully taken into account, namely all resonant and non-resonant contributions are included in the fixed-order calculation. Selected results for total and differential cross sections are shown for the case of the LHC Run I at the energy of 8 TeV.
Pseudo-Goldstone Boson Effects in Top-Antitop Productions at High Energy Hadron Colliders and Testing Technicolor Models
我们在费米实验室Tevatron Run II和CERN LHC上研究了各种Technicolor（TC）模型中的顶夸克对产生过程p+p（anti-p）-->top+antitop。s通道中性赝戈德斯通玻色子（PGB）通过技术夸克和顶夸克的三角环与胶子耦合产生振幅。计算了具有s通道PGB贡献的不同TC模型的截面。结果表明，PGB效应可以在实验上得到检验，并且在LHC上可以区分不同的TC模型。因此，在LHC上的p+p-->top+antitop过程为TC模型提供了可行的检验。
I present high-order calculations, including soft-gluon corrections, for single-top and top-antitop production cross sections and differential distributions. For single-top production, results are presented for the three different channels in the Standard Model, for associated production with a charged Higgs, and for processes involving anomalous couplings. For top-antitop pair production, total cross sections and top-quark transverse-momentum and rapidity distributions are presented for various LHC energies.
For the first time the next-to-leading-order electroweak corrections to the full off-shell production of two top quarks that decay leptonically are presented. This calculation includes all off-shell, non-resonant, and interference effects for the 6-particle phase space. While the electroweak corrections are below one per cent for the integrated cross section, they reach up to 15% in the high-transverse-momentum region of distributions. To support the results of the complete one-loop calculation, we have in addition evaluated the electroweak corrections in two different pole approximations, one…
Top-Antitop Production and Decay at Threshold at the LHC in QCD Perturbation Theory
INFN, Sezione di Milano-Bicocca（意大利国家核物理研究所米兰比可卡分部）；Dipartimento di Fisica G. Occhialini, Università degli Studi di Milano-Bicocca（米兰比可卡大学G. Occhialini物理系）
We present NLO electroweak corrections to Higgs production in association with off-shell top-antitop quark pairs. The full process $\text{p}\text{p}\to\text{e}^+ν_{\text{e}} μ^-\barν_μ\text{b}\bar{\text{b}} \text{H}$ is considered, and hence all interference, off-shell, and non-resonant contributions are taken into account. The electroweak corrections turn out to be below one per cent for the integrated cross section but can exceed $10\%$ in certain phase-space regions. In addition to its phenomenological relevance, the computation constitutes a major technical achievement as the full NLO virt…
The transverse momentum distribution of the $t\bar{t}$ system is of both experimental and theoretical interest. In the presence of the azimuthally asymmetric divergences, pursuing the resummation at the high logarithmic precision is rather demanding in general. In this paper, we propose the projected transverse momentum spectrum $\mathrm{d}σ_{t\bar{t}}/\mathrm{d} q_τ$, which is derived from the classical $\vec{q}_{\mathrm{T}}$ spectrum by integrating out the rejection component $q_{τ_{\perp}}$ with respect to a reference unit vector $\vecτ$, to serve as an alternative resolution to curb those …
We review that the heavy CP-even MSSM Higgs boson is still a viable candidate to explain the Higgs signal at 125 GeV. This is possible in a highly constrained parameter region, that will be probed by LHC searches for the CP-odd Higgs boson and the charged Higgs boson in the near future. We briefly discuss the new benchmark scenarios that can be employed to maximize the sensitivity of the experimental analysis to this interpretation.
We present the results of the computation of the next-to-leading order QCD corrections to the production cross section of a Higgs boson in association with a top-antitop pair at the LHC, including the three relevant dimension-six operators ($O_{t φ}, O_{φG}, O_{tG}$) of the standard model effective field theory. These operators also contribute to the production of Higgs bosons in loop-induced processes at the LHC, such as inclusive Higgs, $Hj$ and $HH$ production, and modify the Higgs decay branching ratios for which we also provide predictions. We perform a detailed study of the cross section…
