Single Transverse Spin Asymmetry as a New Probe of Standard-Model-Effective-Field-Theory Dipole Operators

Area of Science:

• High Energy Physics
• Particle Physics
• Beyond Standard Model Physics

Background:

• Electroweak dipole operators in SMEFT are crucial for probing new physics beyond the Standard Model (SM).
• Current experimental constraints on these operators are weak due to limited interference with SM amplitudes in cross-section observables.

Purpose of the Study:

• To introduce a novel method for constraining electroweak dipole operators by utilizing single transverse spin asymmetries.
• To demonstrate the effectiveness of this method at future electron-positron colliders with transversely polarized beams.

Main Methods:

• Exploiting the helicity-flipping nature of dipole operators.
• Analyzing azimuthal cosϕ and sinϕ distributions arising from the interference of electron dipole operators with SM amplitudes.
• Utilizing transversely polarized electron and positron beams.

Main Results:

• The proposed method can improve constraints on electron dipole couplings by 1-2 orders of magnitude.
• The method is independent of other new physics operators.
• It allows for simultaneous constraints on both real and imaginary parts of the couplings.

Conclusions:

• Single transverse spin asymmetries provide a powerful new tool for probing new physics beyond the Standard Model.
• This technique offers a significant opportunity to investigate potential CP-violating effects.
• Future electron-positron colliders can greatly benefit from this enhanced sensitivity to electroweak dipole operators.