ILC Workshop on Potential Experiments (ILCX2021)

Probing then minimal $U(1)_X$ model at future electron-positron collider via fermion pair production

27 Oct 2021, 15:50

20m

Room #4 (Zoom Meeting ID: 840 3553 0145)

Oral presentation using Zoom Session H: BSM particle production H-2: BSM particle production

Speaker

Arindam Das

Description

The minimal $𝑈(1)_𝑋$ extension of the Standard Model (SM) is a well-motivated new physics scenario, where the anomaly cancellation requirement dictates the new neutral gauge boson $(𝑍^\prime)$ couplings with the SM fermions in terms of two scalar charges ($𝑥_𝐻$ and $𝑥_\Phi$). In this paper, we investigate the SM charged fermion pair production mechanism for different values of these scalar charges in the $𝑈(1)_𝑋$ scenario at future electron-positron colliders, i.e. $𝑒^+𝑒^− \to 𝑓\overline{𝑓}$. Apart from the standard photon and 𝑍 boson exchange for this process, this model features a 𝑠-channel (or both $𝑠$ and $𝑡$-channel for $𝑓=𝑒^−$) $𝑍^\prime$-boson exchange, which interferes with the SM processes. Considering the dilepton and dijet signatures from the heavy resonance we estimate the bounds on the $U(1)_𝑋$ coupling $(𝑔^\prime)$ and the $𝑍^\prime$ mass $(𝑀_𝑍^\prime)$. Considering the LEP-II results and prospective International Linear Collider (ILC) bounds on the effective scale for the four fermion interaction we estimate the reach on $𝑀_{𝑍^\prime}$/$𝑔^\prime$ for different center of mass energies. We study the angular distributions, forward-backward ($\mathcal{A}_{\rm{FB}}$), left-right ($\mathcal{A}_{\rm{LR}}$) and left-right forward-backward ($\mathcal{A}_{\rm{LR,~FB}}$) asymmetries of the $𝑓\overline{𝑓}$ final states which can show substantial deviations from the SM results, even for a multi-TeV $𝑍′$. This provides a powerful complementary way to probe the heavy $𝑍^\prime$ parameter space beyond the direct reach of the Large Hadron Collider (LHC), as well as an effective way to determine the 𝑈$(1)_𝑋$ charges.

Presentation materials

ADAS_ILCX2021_BSM.pdf