No Arabic abstract
The exclusive two-photon production at the LHC of pairs of W and Z bosons provides a novel and unique test-ground for the electroweak gauge boson sector. In particular it offers, thanks to high gamma-gamma center-of-mass energies, large and direct sensitivity to the anomalous quartic gauge couplings otherwise very difficult to investigate at the LHC. An initial analysis has been performed assuming leptonic decays and generic acceptance cuts. Simulation of a simple counting experiment has shown for the integrated luminosity of 10 fb-1 at least four thousand times larger sensitivity to the genuine quartic couplings, a_0^W, a_0^Z, a_C^W and a_C^Z, than those obtained at LEP. The impact of the unitarity constraints on the estimated limits has been studied using the dipole form-factors. Finally, differential distributions of the decay leptons have been provided to illustrate the potential for further improvements of the sensitivities.
Experimental prospects for studying high-energy photon-photon and photon-proton interactions at the CERN Large Hadron Collider (LHC) are discussed. Cross sections are calculated for many electroweak and beyond the Standard Model processes. Selection strategies based on photon interaction tagging techniques are studied. Assuming a typical LHC multipurpose detector, various signals and their irreducible backgrounds are presented after applying acceptance cuts. Prospects are discussed for the Higgs boson search, detection of supersymmetric particles and of anomalous quartic gauge couplings, as well as for the top quark physics.
The vector boson scattering at the Large Hadron Collider (LHC) is sensitive to anomalous quartic gauge couplings (aQGCs). In this paper, we investigate the aQGC contribution to $ W gamma jj$ production at the LHC with $sqrt{s}=13$ TeV in the context of an effective field theory (EFT). The unitarity bound is applied as a cut on the energy scale of this production process, which is found to have significant suppressive effects on the signals. To enhance the statistical significance, we analyse the kinematic and polarization features of the aQGC signals in detail. We find that the polarization effects induced by the aQGCs are unique and can discriminate the signals from the SM backgrounds well. With the proposed event selection strategy, we obtain the constraints on the coefficients of dimension-8 operators with current luminosity. The results indicate that the process $pp to W gamma jj$ is powerful for searching for the $O_{M_{2,3,4,5}}$ and $O_{T_{5,6,7}}$ operators.
In this paper, we investigate the contributions of anomalous quartic gauge couplings (aQGCs) to $Zgamma jj$ production at the Large Hadron Collider (LHC) in the context of Standard Model effective theory (SMEFT). When energy scale is large, the validity of SMEFT becomes an important issue. To ensure the validity, the unitarity bound is applied in a model independent approach, which is found to have significant suppressive effects on the signals of $O_{M_i}$ operators. The kinematic and polarization features of the aQGC signals are also studied. The polarization effect is useful to highlight the signals of $O_{T_i}$ operators. The sensitivity estimates on dimension-8 operators with unitarity bounds at $sqrt{s}=14$ TeV are obtained.
In this paper we investigate the $eta_c$ production by photon - photon and photon - hadron interactions in $pp$ and $pA$ collisions at the LHC energies. The inclusive and diffractive contributions for the $eta_c$ photoproduction are estimated using the nonrelativistic quantum chromodynamics (NRQCD) formalism. We estimate the rapidity and transverse momentum distributions for the $eta_c$ photoproduction in hadronic collisions at the LHC and present our estimate for the total cross sections at the Run 2 energies. A comparison with the predictions for the exclusive $eta_c$ photoproduction, which is a direct probe of the Odderon, also is presented.
A significant fraction of pp collisions at the LHC will involve (quasi-real) photon interactions occurring at energies well beyond the electroweak energy scale. Hence, the LHC can to some extend be considered as a high-energy photon-photon or photon-proton collider. This offers a unique possibility for novel and complementary research where the available effective luminosity is small, relative to parton-parton interactions, but it is compensated by better known initial conditions and usually simpler final states. This is in a way a method for approaching some of the issues to be addressed by the future lepton collider. Such studies of photon interactions are possible at the LHC, thanks to the striking experimental signatures of events involving photon exchanges, in particular the presence of very forward scattered protons.