[Paper Review] CPT violation in the top sector

José A. R. Cembranos, Arvind Rajaraman+1 more|ArXiv.org|Dec 1, 2005

Particle physics theoretical and experimental studies3 citations

TL;DR

This paper investigates CPT violation in the top quark sector using top-antitop pair production at future colliders. It proposes a model-independent parameter, $ R_{CPT}(t) $, to quantify CPT violation via mass differences between top and anti-top quarks, finding that the lepton + jets channel at the LHC could improve current Tevatron constraints by nearly an order of magnitude, reaching a sensitivity of $ |R_{CPT}(t)| hickapprox 0.014 $ at 95% confidence level.

ABSTRACT

We study the viability of observation of CPT violation in the top sector at future colliders. We show possible studies and different estimates for hadronic and linear colliders. In particular, we will present current constraints for Tevatron and prospects for the LHC and the ILC.

Motivation & Objective

• To assess the feasibility of detecting CPT violation in the top quark sector at future hadronic and linear colliders.
• To establish a model-independent parameter, $ R_{CPT}(t) $, to quantify CPT violation through top-antitop mass differences.
• To evaluate current constraints from the Tevatron and future sensitivities at the LHC and International Linear Collider (ILC).
• To identify the most sensitive experimental channel for probing CPT violation in top quark pair production.
• To guide future precision measurements in the top sector by comparing statistical and systematic uncertainties across collider types.

Proposed method

• Using the invariant mass reconstruction of top and anti-top decay products in the di-lepton and lepton + jets channels to detect mass splitting.
• Applying the parameter $ R_{CPT}(t) = 2(m_t - m_{\bar{t}})/(m_t + m_{\bar{t}}) $ to quantify CPT violation in the top sector.
• Estimating current constraints using CDF and D0 data from the Tevatron, assuming a single peak at $ m_t = m_{\bar{t}} = 163 \pm 2 \text{ (stat.)} \pm 9 \text{ (syst.)} $ GeV.
• Projecting LHC sensitivity using expected statistical uncertainty of 0.9 GeV and systematic uncertainty of 2 GeV for top mass measurements.
• Evaluating ILC sensitivity based on reduced systematic errors and increased statistical precision, though with limited improvement over LHC due to dominant systematics.
• Comparing the di-lepton and lepton + jets channels, favoring the latter due to better signal-to-noise and improved uncertainty control.

Experimental results

Research questions

• RQ1 Can CPT violation in the top quark sector be probed at future hadron and linear colliders using top-antitop pair production?
• RQ2 What is the current experimental bound on $ R_{CPT}(t) $ from Tevatron data?
• RQ3 Which decay channel—di-lepton or lepton + jets—offers the highest sensitivity to CPT violation in top quark pair production?
• RQ4 How much can the LHC improve upon existing constraints on $ R_{CPT}(t) $ compared to the Tevatron?
• RQ5 To what extent can the ILC enhance sensitivity to CPT violation in the top sector, given its expected precision?

Key findings

• Current constraints from the Tevatron yield $ |R_{CPT}(t)| < 0.13 $ at 95% confidence level, based on a conservative combination of statistical and systematic uncertainties.
• The lepton + jets channel provides a stronger bound than the di-lepton channel, with $ R_{CPT}(t) < 9.2 \times 10^{-2} $ from combined CDF and D0 data.
• The LHC is projected to achieve a sensitivity of $ |R_{CPT}(t)| \simeq 0.014 $ at 95% confidence level in the lepton + jets channel, representing nearly an order of magnitude improvement over Tevatron constraints.
• The LHC's improved sensitivity corresponds to a mass splitting of $ m_t - m_{\bar{t}} \simeq 2.4 $ GeV.
• While the ILC offers better statistical precision, systematic uncertainties dominate, resulting in only a modest improvement over the LHC in sensitivity to CPT violation.
• Threshold scan analyses at the ILC are less promising for detecting CPT violation, despite their high sensitivity to top quark mass.