The specificity of searches for W′, Z′ and γ′ coming from extra dimensions

Abstract

Abstract:We discuss the specificity of searches for hypothetical W ′ , Z ′ and γ ′ bosons at hadron colliders in single top quark and µ + ν µ production and Drell-Yan processes assuming these particles to be the Kaluza-Klein excitations of the gauge bosons of the Standard Model. In this case any process mediated by W is also mediated by the whole KK tower of its excitations, whereas to the processes mediated by Z and γ there is not only a contribution from their KK towers, but also from that of the graviton. The contributions of the towers above W ′ , Z ′ and γ ′ and above the first excitation of the graviton are included with the help of effective four-fermion Lagrangians. We compute the cross-sections of these processes taking into account the contributions of the Standard Model gauge bosons, of their first KK modes and of the corresponding KK towers and discuss the impact of the interference between them. For pp-collisions at the LHC with the center of mass energy 14 TeV we found specific changes of the distribution tails due to the interference effects. Such a modification of distribution tails is characteristic for the processes mediated by particles coming from extra dimensions and should always be taken into account when looking for them.

Improved bounds on W−W′ mixing with ATLAS resonant WZ production data at the LHC at Serenkova1, Osland2, Панков3 2019Phys. Rev. D92230View full textAdd to dashboardCite

“…These channels are among the most promising early discoveries at the LHC [3,4]. There have also been many theoretical studies of W boson searches [5][6][7][8][9][10][11][12][13][14] at the LHC. The ATLAS and CMS collaborations set limits on the W production cross section times branching fraction in the process (1), σ(pp → W X) × BR(W → ν), for M W in the 0.15 TeV -6 TeV range.…”

Restrictions on the mass of the KK excitation W′ from the Higgs boson diphoton decay and the single top production.

“…where g is the weak coupling constant, α 1 is the ratio of the wave functions of W and W on the brane, J ±µ is the weak charged current and m W _sum is the mass parameter taking into account the contribution of the KK tower above W [15]. The contact term in Lagrangian (10) is, in fact, Fermi's interaction with the coupling constant g 2 α 2 1 /(2m 2 W _sum ).…”

“…Explicit calculations in UED models with flat extra dimension and in certain stabilized brane-world models show that this mass is just a little larger than that of the W boson. In the present paper we will take the value 1.4 m W for the effective mass of the KK tower above W that was also used in [15,20].…”

“…The excitations of the W boson can contribute to various processes with the Standard Model particles. In particular, in paper [15] the contributions of the W boson KK tower to the single top and muon production processes have been studied. The W boson excitations can also contribute to the diphoton decay of the Higgs boson via the triangle diagrams.…”

The specificity of the interactions of electroweak gauge bosons coming from extra dimensions

“…In this case non-trivial interference between the contributions, for example, of W and W ′ , to various processes [32][33][34][35][36][37] could influence the experimental observation of the latter and the exclusion limits for their masses [38][39][40][41]. Interference of W ′ , Z ′ and γ ′ with the SM bosons and with the rest of corresponding KK-towers coming from extra dimensions leads to certain changes in invariant mass and P t distributions [42,43]. However this specific feature of the EW gauge boson KK excitations is also rather delicate for experimental detection.…”