24-30 July 2016
Highfield Campus, University of Southampton
Europe/London timezone

Up and down quark masses and corrections to Dashen's theorem from lattice QCD and quenched QED

26 Jul 2016, 15:20
20m
Building 67 Room 1007 (Highfield Campus, University of Southampton)

Building 67 Room 1007

Highfield Campus, University of Southampton

Highfield Campus, Southampton SO17 1BJ, UK
Talk Standard Model Parameters and Renormalization Standard Model Parameters and Renormalization

Speaker

Mr Lukas Varnhorst (University of Wuppertal)

Description

We present a determination of the corrections to Dashen's theorem and of the individual up and down quark masses from a lattice calculation based on quenched QED and $N_f=2+1$ QCD simulations with 5 lattice spacings down to $0.054 \, \mbox{fm}$. The simulations feature lattice sizes up to $6 \, \mbox{fm}$ and average up-down quark masses all the way down to their physical value. For the parameter which quantifies violations to Dashens's theorem we obtain $\epsilon=0.73(2)(5)(17)$, where the first error is statistical, the second is systematic, and the third is an estimate of the QED quenching error. For the light quark masses we obtain, $m_u=2.27(6)(5)(4) \ \mbox{MeV}$ and $m_d=4.67(6)(5)(4) \, \mbox{MeV}$ in the $\bar{MS}$ scheme at $2 \, \mbox{GeV}$ and the isospin breaking ratios $m_u/m_d=0.485(11)(8)(14)$, $R=38.2(1.1)(0.8)(1.4)$ and $Q=23.4(0.4)(0.3)(0.4)$. Our results exclude the $m_u=0$ solution to the strong CP problem by more than 24 standard deviations.

Primary author

Mr Lukas Varnhorst (University of Wuppertal)

Presentation Materials