Why should we care about the top quark Yukawa coupling?

TL;DR

This paper discusses how precise measurements of the top quark Yukawa coupling can provide insights into the stability of the electroweak vacuum and the possible existence of new physics at very high energy scales.

Contribution

It reviews recent theoretical and experimental work on the critical top Yukawa coupling and emphasizes the importance of precision in determining its value for understanding new physics.

Findings

The critical Yukawa coupling $y_t^{crit}$ aligns with vacuum stability requirements.

Experimental measurements of $y_t$ have uncertainties affecting new physics scale estimates.

The scale of new physics varies widely based on $y_t$ uncertainties, from $10^7$ GeV to the Planck scale.

Abstract

In the cosmological context, for the Standard Model to be valid up to the scale of inflation, the top quark Yukawa coupling $y_t$ should not exceed the critical value $y_t^{crit}$, coinciding with good precision (about 0.02%) with the requirement of the stability of the electroweak vacuum. So, the exact measurements of $y_t$ may give an insight on the possible existence and the energy scale of new physics above 100 GeV, which is extremely sensitive to $y_t$. We overview the most recent theoretical computations of $y_t^{crit}$ and the experimental measurements of $y_t$. Within the theoretical and experimental uncertainties in $y_t$ the required scale of new physics varies from $10^7$ GeV to the Planck scale, urging for precise determination of the top quark Yukawa coupling.