# Inferring the covariant $\Theta$-exact noncommutative coupling in the top quark pair production at linear colliders

## TL;DR

This paper investigates how a novel non-minimal coupling in a covariant noncommutative standard model affects top quark pair production at linear colliders, providing bounds on the noncommutative scale using polarized and unpolarized beams.

## Contribution

It introduces a new covariant noncommutative coupling invariant under VSR Lorentz subgroup and analyzes its effects on top quark production with polarized beams, deriving bounds on the noncommutative scale.

## Key findings

- Threshold energy for probing NCSM depends on the noncommutative scale and coupling.
- Polarized beams extend the sensitivity to higher noncommutative scales.
- Bounds on the noncommutative scale are established at 1.0 to 2.8 TeV.

## Abstract

A novel non-minimal interaction of neutral right-handed fermion and abelian gauge field in the covariant $\Theta$-exact noncommutative standard model (NCSM) which is invariant under Very Special Relativity (VSR) Lorentz subgroup, opens an avenue to study the top quark pair production at linear colliders. Here the coupling denoted as $\kappa$ and the noncommutative (NC) scale $\Lambda$. In this work, we consider two types of analysis, one is without considering helicity basis and another, considering helicity states of the polarized and unpolarized initial and final particles. In the first case, when $\kappa$ is positive and for certain values of $\Lambda$, we arrived a specific threshold value of machine energy (units of GeV) $\sqrt{s_0}$ ($ \simeq 2.52 ~\Lambda + 39$ ) may be quite useful to probe NCSM with the unpolarized beam. The statistical $\chi^2$ analysis of the azimuthal anisotropy is quite possible when $\kappa$ takes negative value $0 >\kappa> -0.596$ which persuade a lower limit on NC scale $\Lambda$ ($ 1.0\, \text{to} \, 2.4\,\text{TeV}$) at $\kappa_{max}=-0.296 (95\%$ C.L) according to luminosity ranging from $100\,fb^{-1} \text{to}1000\,fb^{-1}$ at machine energy $\sqrt{s}=1.4\,\text{TeV}\,\text{and}\, 3.0\,\text{TeV}$. In another case, we performed polarized beam analysis to probe NCSM in the light of following observables azimuthal anisotropy, helicity correlation, and top quark helicity left-right asymmetry. The polarization of the initial beam $\{ P_{e^{-}},P_{e^{+}}\} = \{-0.8,0.3\}( \{-0.8,0.6\})$ enhances the ranges of lower limit on $\Lambda$, $i.e.\, 1.13 \, \text{to} \, 2.80\,\text{TeV}$ at $\kappa_{max}$ alongside the $\kappa_{max}$ enhanced into $-0.5445 \,(-0.607)$ $95\%$C.L accord with luminosity and $\sqrt{s}$. Finally, we studied the intriguing mixing of the UV and the IR by invoking $T(2)$ VSR Lorentz subgroup symmetry on NC tensor $\Theta_{\mu\nu}$.