相关论文: Scalar Leptoquark Contribution to Two Photon Elast…
Vector-like quarks (VLQs) are attractive extensions to the Standard Model. They mix with the SM quarks and can lead to rich phenomenology. Determination of VLQ's interaction structure with the SM is then an important issue, which can be…
High energy lepton scattering has been the primary tool for mapping out the quark distributions of nucleons and nuclei. Data on the proton and deuteron have shown that there is a fundamental connection between the low and high energy…
We compute the decoupling function of the MSbar renormalized fine-structure constant up to four-loop order in perturbative QCD. The results are used in order to determine the related top-quark contributions to the Higgs-boson decay into two…
A search for a first generation scalar leptoquark (LQ) has been performed using the data collected by the OPAL detector in 1996 at e+e- centre-of-mass energies sqrt{s} of 161 and 172 GeV. It is assumed that a single leptoquark can be…
The contributions of the scalar leptoquark doublets into widths of the $K^0_L \to e^{\mp} \mu^{\pm}$, $B^0 \to e^{\mp} \tau^{\pm}$ decays are calculated in MQLS model with Higgs mechanism of the quark-lepton mass splitting. The resulted…
We present the complete two-loop corrections in massless QCD for the production of two photons and a jet, taking into account all color structures. In particular, we analytically compute all two-loop helicity amplitudes for the…
The two-photon exchange contribution to the single spin asymmetries with the spin orientation normal to the reaction plane is discussed for elastic electron-proton scattering in Regge regime. For this, the equivalent photon approximation is…
We revisit scalar leptoquark pair-production at hadron colliders and significantly improve the level of precision of the cross section calculations. Apart from QCD contributions, we include lepton t-channel exchange diagrams that turn out…
We use a new scaling variable $\xi_w$, and add low $Q^2$ modifications to GRV98 leading order parton distribution functions such that they can be used to model electron, muon and neutrino inelastic scattering cross sections (and also…
We calculate the two-loop QCD correction to the scalar quark contributions to the electroweak gauge-boson self-energies at zero momentum-transfer in the supersymmetric extension of the Standard Model. We then derive the $O(\alpha_s)$…
The processes of lepton-nucleon scattering, including ones with both polarized beams, at high energy provide relevant information about interaction and particles structure, allowing to analyze nucleon spin structure. As energy and…
Measurements of the ratio of $B \to K^* \mu \mu $ to $B \to K^* e e $ branching fractions, $R_{K^*}$, by the LHCb collaboration strengthen the hints from previous studies with pseudoscalar kaons, $R_K$, for the breakdown of lepton…
We present the cross section for pair production of scalar leptoquarks $LQ$ in $p\bar{p}$ collisions, $p+\bar{p} \to LQ + \bar{LQ} + X$, at the Fermilab Tevatron in next-to-leading order QCD. Including the higher-order corrections…
The measurements of high energy \bar p p and pp elastic at ISR, SPS and Tevatron colliders have provided usefull informations on the behavior of the scattering amplitude. A large step in energy domain is accomplished with the LHC collider…
Predictions for the angular distribution of massive quarks and leptons are presented, including QCD and QED corrections. Recent results for the fermionic part of the two-loop corrections to the electromagnetic form factors are combined with…
We compute the dominant logarithmically enhanced two-loop electroweak corrections to the electron-positron scattering differential cross section in the high energy limit for large scattering angles. Depending on the scattering angle and…
In the Minimal Supersymmetric Standard Model, one of the scalar top quarks can be relatively light and its couplings to Higgs bosons strongly enhanced. I will discuss two consequences of this feature: 1) the effects of scalar top loops on…
We compute the two-loop QCD helicity amplitudes for the production of a Higgs boson in association with a bottom-quark pair at a hadron collider. We take the approximations of leading colour and work in the five flavour scheme, where the…
We use the spinor methods of the CALKUL collaboration, as realized by Xu, Zhang and Chang, to calculate the differential cross section for e+ e- --> e+ e- + 2 photons for c.m.s. energies in the SLC/LEP regime. An explicit complete formula…
We study amplitude zeros in radiative decay processes with a photon or a gluon emission of all possible scalar particles(e.g. scalar leptoquarks) which may interact with the usual fermions in models beyond the standard model. For the decays…