Electromagnetic dipole moments of the top quark

TL;DR

This paper reviews how recent experimental measurements constrain the electromagnetic dipole moments of the top quark, highlighting the current limitations and potential improvements with future collider data.

Contribution

It provides a comprehensive analysis of how B meson decay measurements and collider data jointly constrain top quark dipole moments, emphasizing the need for more precise measurements.

Findings

B->Xs gamma measurements set stringent bounds on top quark dipole moments.

Current CDF measurement errors are too large for competitive bounds.

LHC could improve constraints with more precise measurements.

Abstract

Recent measurements like the t tbar gamma production by CDF as well as the Br(B ->Xs gamma) and ACP (B->Xs gamma) are used to constrain the magnetic and electric dipole moments of the top quark. The B->Xs gamma measurements by themselves define an allowed parameter region that sets up stringent constraints on both dipole moments. Actually, significantly more stringent than previously reported. The measurement by CDF has a 37% error that is too large to set any competitive bounds, for which a much lower 5% error would be required at least. On the other hand, because of the LHC's higher energy (apart from its higher luminosity) the same measurement performed there could indeed further constrain the allowed parameter region given by the B->Xs gamma measurement.