# Physics at the LHC and beyond

29 September 2015 to 2 October 2015
DESY Hamburg
Europe/Berlin timezone

## Quark isospin asymmetry at small and large x

1 Oct 2015, 16:05
15m
Seminar room 4a (DESY Hamburg)

### Speaker

Sergey Alekhin (Hamburg University)

### Description

We discuss an improved determination of the up- and down-quark distributions in the proton using recent data on charged lepton asymmetries from $W^\pm$ gauge-boson production at the LHC and Tevatron. The analysis is performed in the framework of a global fit of parton distribution functions. The results are consistent with a non-zero iso-spin asymmetry of the sea, $x(\bar d - \bar u)$, at small values of Bjorken $x\sim 10^{-3}$ indicating a delayed onset of the Regge asymptotics of a vanishing $(\bar d - \bar u)$-asymmetry at small-$x$.

### Primary author

Sergey Alekhin (Hamburg University)

### Co-authors

Johannes Bluemlein (DESY-Zeuthen) Ringaile Placakyte (DESY) Sven-Olaf Moch (Hamburg University)

 Slides