Model-independent sensitivity estimates for the electromagnetic dipole moments of the τ -lepton at the CLIC

Abstract

We establish model-independent sensitivity on the anomalous magnetic and electric dipole moments of the τ-lepton using the two-photon processes γγ → τ þ τ − and γγ → τ þ τ − γ. We use L ¼ 10, 50, 100, 300, 500, 1000, 1500, 2000, 3000 fb −1 data collected with the future e þ e − linear collider such as the CLIC at ffiffi ffi s p ¼ 380, 1500, 3000 GeV, and we consider systematic uncertainties of δ sys ¼ 0%, 3%, 5%. We obtain sensitivity estimates at 95% C.L. on the anomalous dipole moments to the τ-lepton −0.00015 ≤ã τ ≤ 0.00017 and jd τ ðecmÞj ¼ 9.040 × 10 −19 that may be achievable in future experiments. Our results show that the processes under consideration are very promising for probing the dipole moments of the τ-lepton at the future e þ e − linear collider at the γγ mode.

Sensitivity on the electromagnetic dipole moments of the tau-lepton at the CLIC

“…Our results for the process γγ → τ + τ − at the CLIC could improve the sensitivity on anomalous electromagnetic dipole moments of τ-lepton with respect to the existing experimental bounds (see Table I in Ref. [6]) by 2 orders of magnitude. The best sensitivities obtained onã τ andd τ were −0.00015 ≤ã τ ≤ 0.00017 and |d τ | = 9.040 × 10 −19 , respectively, as shown in Tables III-V in Ref.…”

“…The best sensitivities obtained onã τ andd τ were −0.00015 ≤ã τ ≤ 0.00017 and |d τ | = 9.040 × 10 −19 , respectively, as shown in Tables III-V in Ref. [6]. These are compared with experimental results of earlier studies for a linear collider as published by the DELPHI and BELLE Collaborations [1,4].…”

“…These results that we get for the process γγ → τ + τ − at the CLIC indicate the improved sensitivity on anomalous electromagnetic dipole moments of tau-lepton with respect to the existing experimental bounds by two orders of magnitude. The best sensitivities obtained on a τ and d τ are −0.00012 ≤ a τ ≤ 0.00014 and |d τ (ecm)| = 7.445 × 10 −19 [6]. Furthermore, there has been extensive theoretical work done in new physics beyond de Standard Model that contributes to dipole moments of tau-lepton: Left-right symmetric model [17], E 6 superstring models [18], simplest little Higgs model [19], and 331 model [20].…”

“…1. We determine sensitivity estimates on the electromagnetic dipole moments of the tau-lepton a τ and d τ via the two-photon process [6]. The future Collider CLIC can produce very hard photons at high luminosity in Compton backscattering of laser light off high energy e + e − beams.…”

Feasibility of τ -lepton electromagnetic dipole moments measurement using bent crystal at the LHC

“…In Refs. [18,19] the potential of future colliders for improvement of the current experimental bounds is investigated. In particular, at the electron-positron linear collider CLIC in the processes γ γ → τ + τ − , γ γ → τ + τ − γ, and in the reactions e − e + → e − γ e + → ν e τ −ν τ e + with quasireal photon and e − γ → ν e τ −ν τ with Compton back-scattering photon.…”