AbstractAt the proposed electron-proton collider LHeC electroweak interactions can be uniquely studied in a largely unexplored kinematic region of spacelike momentum transfer. We simulate inclusive neutral- and charged-current deep-inelastic lepton proton scattering cross section data at center-of-mass energies of 1.2 and 1.3 TeV, and estimate the uncertainties of Standard Model parameters as well as of parameters describing physics beyond the Standard Model. A precision at sub-percent level is expected for the measurement of the weak neutral-current couplings of the light-quarks to the Z boson, $$g_{A/V}^{u/d}$$
g
A
/
V
u
/
d
, improving their present precision by more than an order of magnitude. The weak mixing angle can be determined with a precision of about $$\Delta \sin ^2\theta _\text {W}=\pm \,0.00015$$
Δ
sin
2
θ
W
=
±
0.00015
, and its scale dependence can be studied in the range between about 25 and 700 GeV. An indirect determination of the W-boson mass in the on-shell scheme is possible with an experimental uncertainty down to $$\Delta m_{W}=\pm \,6\,\text {MeV}$$
Δ
m
W
=
±
6
MeV
. We discuss how measurements in deep-inelastic scattering compare with those in the timelike domain, and which aspects are unique, for instance electroweak parameters in charged-current interactions. We conclude that the LHeC will determine electroweak physics parameters, in the spacelike region, with unprecedented precision leading to thorough tests of the Standard Model and possibly beyond.
DEEP INELASTIC SCATTERING AT HERA