Probing light mediators with recent PandaX-4T low-energy electron recoil data

Neutrinos elastically scattered off atomic electrons offer a unique opportunity to probe the Standard Model (SM) and beyond SM physics. In this work, we examine the new physics effects of light mediators through elastic neutrino-electron scattering using solar neutrinos at the low energy range of PandaX-4T. These mediators, with a mass less than 1 GeV, are common properties of extensions to the SM. Accordingly, we consider universal light mediator models involving scalar, vector, and tensor interactions allowed by Lorentz invariance, and the anomaly-free <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:mi>U</a:mi><a:mo stretchy="false">(</a:mo><a:mn>1</a:mn><a:msup><a:mrow><a:mo stretchy="false">)</a:mo></a:mrow><a:mrow><a:mo>′</a:mo></a:mrow></a:msup></a:mrow></a:math> extensions of the SM with a new vector mediator such as the <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:msub><e:mi>L</e:mi><e:mi>e</e:mi></e:msub><e:mo>−</e:mo><e:msub><e:mi>L</e:mi><e:mi>μ</e:mi></e:msub></e:math>, <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"><g:msub><g:mi>L</g:mi><g:mi>e</g:mi></g:msub><g:mo>−</g:mo><g:msub><g:mi>L</g:mi><g:mi>τ</g:mi></g:msub></g:math> and <i:math xmlns:i="http://www.w3.org/1998/Math/MathML" display="inline"><i:msub><i:mi>L</i:mi><i:mi>μ</i:mi></i:msub><i:mo>−</i:mo><i:msub><i:mi>L</i:mi><i:mi>τ</i:mi></i:msub></i:math> gauge models in which the charges are exclusively leptonic. The new physics effects are analyzed by embedding each model into the SM process using solar neutrino flux. We obtain novel constraints on the coupling-mass plane of these models from the latest Run0 and Run1 datasets of the PandaX-4T experiment. We also compare our results with other limits derived from various terrestrial and astrophysical experiments. Our analysis results reveal more stringent limits in some regions of parameter space.