# P2: The weak charge of the proton

### Research areas

• Experimental particle and hadron physics
• Theoretical particle and hadron physics
• Accelerator physics

### Goals

The main objective of project P2 is the extraction of a precise value of the weak mixing angle $${\sin}^2 \theta_W$$ from a measurement of the parity-violating (PV) asymmetry in elastic electron proton scattering, with an accuracy comparable to that of the existing collider measurements of $$\Delta{\sin}^2\theta_W$$ = 0.0003 (i.e., 0.13 % relative uncertainty).

The major goals for the second funding period are:

• Design and construction of a spectrometer/integrating detector system for the measurement of the parity-violating asymmetry in elastic electron-proton scattering based on measuring the integral flux of scattered electrons with quartz Cherenkov detectors ("flux integration").
• Design and construction of a tracking system for the measurement of the average momentum transfer $$<Q^2>$$ based on thin silicon pixel detectors, see the following figure.
• Development of high precision polarimetry for electron beams.
• Calculation of electroweak radiative corrections for the measurement of the weak charge at MESA.