Back to CINP FunSym

Fundamental symmetries at the EIC

Location: Brookhaven National Laboratory, New York, USA
Participating Canadian institutions: Manitoba, Regina
International partners: USA and others
External link

In addition to the hadronic physics program, the EIC presents opportunities in the area of fundamental symmetries and neutral current weak interactions.

Precision measurements of fundamental observables in the electroweak sector of the Standard Model have allowed us to impose strict limits on the existence of potential new physics beyond the Standard Model. Canadian subatomic physicists were instrumental in such experiments at Jefferson Lab in the PV-DIS experiment ¹ and QWeak experiment ².

The EIC presents opportunities for isoscalar hadrons, i.e. electron–deuteron collisions, which have never been available. Measurements of interference structure functions \(F^{\gamma Z}_1\) and \(F^{\gamma Z}_3\) in polarized electron–unpolarized deuteron scattering will allow for clean separation of the weak vector and weak axial-vector quark couplings, and determination of the electroweak mixing angle \(\sin^2\theta_W\) in the poorly explored region between 10 and 70 GeV (see Figure 1). Additionally, the measurements of \(F^{\gamma Z}_3\) will improve our knowledge of the \(V_{ud}\) term in the \(u\)-quark unitarity relation for the CKM matrix, another avenue for Standard Model tests.

The EIC presents opportunities outside hadronic physics as well, for example in the area of fundamental symmetries. New channels for Standard Model tests of lepton flavor violation present themselves through \(e^- \to \tau^-\) decays. At the anticipated integrated luminosities of 100 fb\(^{-1}\), this channel holds discovery potential for leptoquarks, \(R\)-parity violating supersymmetry, leptophobic \(Z^{\prime}\) bosons, and other charged lepton flavor violation theories.

In Spring 2020, the U. Manitoba members of the EIC-Canada Collaboration organized a (virtual) workshop on Electroweak and Beyond the Standard Model physics at the EIC that attracted over 80 theoretical and experimental subatomic physicists. The outcomes of this workshop are directly impacting the Yellow Report process.

Accurate knowledge of the electron beam polarization is important for the electroweak mixing angle program. The U. Manitoba group plans to apply its expertise in Compton polarimetry at HERA, Jefferson Lab, and the EIC. The development of Compton polarimetry for the EIC has significant synergies with the upgrade of the Belle II facility to use polarized electrons in their high energy ring.