Sensitivity to anomalous quartic gauge couplings in photon-photon interactions at the LHC

Abstract

A dW γγ dW γγ .A set of VFDs at 220 m or 420 m from the LHC interaction points will be capable of tagging photon interactions within the wide photon energy range of 20 GeV < E γ < 900 GeV [5,6]. In Fig. 1 also the γγ luminosity spectrum is shown assuming double tagging (i.e. requesting both forward protons to be detected). One should note that apart from such elastic two-photon processes where both protons have survived the interaction, the inelastic production can also be considered, s W0 σ γγ dL γγ s = 14 TeV the EP predicts the photon-photon luminosity spectrum as shown in Fig. 1, where dL γγ /dW γγ is defined by the relation between the proton-proton and γγ cross-sections assuming a minimal center-of-mass energy W 0 :The cross sections of two-photon pair production are in general determined by the mass, spin and charge of the produced particles, so the rate of produced particles at the LHC can be well predicted using the Equivalent Photon Approximation for the equivalent photon fluxes [4]. For proton-proton collisions at √The exclusive two-photon production at the LHC of pairs of W and Z bosons provides a novel and unique testground for the electroweak gauge boson sector. In particular it offers, thanks to high γγ 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 W 0 , a Z 0 , and a W C and a Z C , 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. LHC as a photon colliderThe γγ exclusive production of pairs of charged particles offers interesting potential for signals of new physics at the LHC. In a recent paper [1], the initial comprehensive studies of high energy photon interactions at the LHC were reported. In the present contribution, the selected results on the gauge boson pairs discussed in Ref.[1] are introduced and supplemented by new results.The exclusive two-photon production, pp → pXp, provides clean experimental conditions, thanks to absence of the proton remnants. Well defined final states can be then selected, and precisely reconstructed. Moreover, detection of the two final state protons, scattered at almost zerodegree angle, in the dedicated very forward detectors (VFDs), provides another striking signature, effective also at high luminosity and with large event pile-up [2,3]. In addition, the photon energies can be then measured and used for the event kinematics reconstruction. Finally, virtualities of the exchanged photons are on average very small, and are limited from above due to the proton...

W + W − pair production in proton-proton collisions: small missing terms

“…[5] and turned out to be small at high masses but dominating at low masses. The W + W − pair production signal is particularly sensitive to new Physics contributions in the γγ → W + W − subprocess [1][2][3][4]. Similar analysis has been considered recently for γγ → ZZ and γγ → γγ [1,2,6].…”

“…The pp → ppW + W − reaction is particularly interesting in the context of γγW W coupling [1][2][3][4]. The general diagram for the exclusive reaction is shown in figure 2.…”

“…in refs. [1][2][3][4]. The exclusive cross section could be also calculated more precisely in four-body calculations using the corresponding 2 → 4 matrix element.…”

“…The photonphoton contribution was recently considered in the literature [1][2][3][4] and dominates at W pair masses. The exclusive QCD diffractive mechanism of central exclusive production of W + W − pairs (in which diagrams with intermediate virtual Higgs boson as well as quark box diagrams are included) was discussed in ref.…”

Precise photoproduction of the charged top-pions at the LHC with forward detector acceptances

“…[19] and cross sections are calculated for many EW and BSM processes. Many phenomenological studies of photonproduced processes are summarized here, involving: standard model productions [20][21][22], supersymmetry [23][24][25][26][27][28], extra dimensions [29][30][31], unparticle physics [32], gauge boson self-interactions [33][34][35][36][37][38][39][40][41][42], neutrino electromagnetic properties [43][44][45], top quark physics [21,22,[46][47][48], and triplet Higgs production [49], etc.…”