Related papers: Multiphoton Production at High Energies in the Sta…
We examine multiphoton production in the electroweak sector of the Standard Model in the high energy limit using the equivalence theorem in combination with spinor helicity techniques. We obtain recursion relations for currents consisting…
We present the matrix element of gamma gamma ->4l process with four charge particles in final state. The constructions are performed in frame of Standard Model of electroweak interaction using the helicity amplitude method . Every possible…
The strong electromagnetic fields carried by relativistic highly charged ions make heavy-ion colliders attractive places to study photonuclear interactions and two-photon interactions. At RHIC, three experiments have studied coherent…
High energy multiparticle photoproduction off nuclear targets is studied. The photon is assumed to interact in direct scattering processes or as a resolved $q\bar{q}$-state according to the Generalized Vector Dominance Model. In the…
High intensity back-scattered laser beams will allow the efficient conversion of a substantial fraction of the incident lepton energy into high energy photons, thus significantly extending the physics capabilities of an electron-electron or…
The analytical calculation of helicity amplitudes for hard photon and gluon bremsstrahlung radiation are described using the spinor formalism for processes of the type $\bar{q} q \to g \gamma$ and $q g \to q \gamma$. The presented…
Single top quark production at hadron colliders allows a direct measurement of the top quark charged current coupling. We present the complete tree-level helicity amplitudes for four processes involving the production and semileptonic decay…
We estimate production cross sections for 2-body resonances of the Electroweak Symmetry Breaking sector (in $W_LW_L$ and $Z_LZ_L$ rescattering) from $\gamma\gamma$ scattering. We employ unitarized Higgs Effective Field Theory amplitudes…
We present an indepth investigation of certain aspects of the two level on resonant multiphoton approximation to pair production from vacuum in the presence of strong electromagnetic fields. Numerical computations strongly suggest that a…
LHC run-II has a great potential to search for new resonances in the diphoton channel. Latest 13 TeV data already put stringent limits on the cross sections in the diphoton channel assuming the resonance is produced through the gluon-gluon…
The pair production of charged heavy leptons via two photon fusion is considered for hadron collisions at SSC and LHC energies. Rates for the inelastic process $pp \rightarrow \gamma \gamma X \rightarrow L^+L^-X$ and the elastic process $pp…
We consider the production of a single Standard Model (SM) Higgs boson ($h^0$) in association with a photon at the future Linear collider (LC) in the context of a type-II seesaw model. The type-II seesaw model extends the SM particle…
Extending the Higgs sector of the Standard Model (SM) by just one additional Higgs doublet field leads to the two-Higgs-doublet model (2HDM). In the Type-I $Z_2$-symmetric limit of the 2HDM, all the five new physical Higgs states can be…
The helicity amplitudes of the high-energy photon splitting in the external Coulomb field are obtained exactly in the parameter $\al$. The cases of screened and unscreened potentials are investigated. The consideration is based on the…
The strong electromagnetic fields of short duration associated with relativistic heavy ions make a heavy-ion collider a unique tool to study two-photon and photonuclear collisions. In this talk, we introduce the principles of…
The charged Higgs pair production via photon-photon collisions is investigated in the framework of two Higgs doublet model (2HDM), taking into account a full set of one-loop-level scattering amplitudes, i.e., including electroweak (EW)…
We compute two-loop helicity amplitudes in QCD for diphoton production through quark- and gluon-initiated channels, accounting for a massive internal quark loop by keeping its full mass dependence. Using physical projectors, we directly…
As continuation of our previous paper we further develop our new method for calculating helicity amplitudes of jet-like QED processes described by tree diagrams, applying it to lepton pair production. This method consists in replacing…
We derive an explicit formula for the low energy limits of the one-loop, on-shell, massive N-photon amplitudes, for arbitrary N and all helicity assignments, in scalar and spinor QED. The two-loop corrections to the same amplitudes are…
In many new physics scenarios, the particle content of the Standard Model is extended and the Higgs couplings are modified, sometimes without affecting single Higgs production. We analyse two models with additional quarks. In these models,…