# The 34th International Symposium on Lattice Field Theory (Lattice 2016)

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

### 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

 Slides
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