Probing lepton flavor violation via $e\tau$ production in an effective framework at a future electron-positron circular coll

In the Standard Model framework, lepton flavor is conserved in interactions. However, it can be violated in certain scenarios beyond the Standard Model. In this study, we consider (e^{±}\tau^{\mp}) <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:mo stretchy="false" form="prefix">(</mml:mo> <mml:msup> <mml:mi>e</mml:mi> <mml:mo>±</mml:mo> </mml:msup> <mml:msup> <mml:mi>τ</mml:mi> <mml:mo>∓</mml:mo> </mml:msup> <mml:mo stretchy="false" form="postfix">)</mml:mo> </mml:mrow> </mml:math> production through a four-Fermi lepton flavor violation interaction at the future electron-positron circular collider (FCC-ee). To constrain the Wilson coefficients at four center-of-mass energies 157.5, 162.5, 240 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow> <mml:mn>157.5</mml:mn> <mml:mo>,</mml:mo> <mml:mn>162.5</mml:mn> <mml:mo>,</mml:mo> <mml:mn>240</mml:mn> </mml:mrow> </mml:math> , and 365 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mn>365</mml:mn> </mml:math> GeV that have been proposed for the FCC-ee, a Standard Model Effective Field Theory (SMEFT) is used. The main sources of background are accounted for, and the study incorporates realistic detector effects. To enhance the results, we combine the individual constraints obtained at each center-of-mass energy. We show that the combined limits improve the sensitivity to lepton flavor violation couplings by a factor of approximately three compared to the individual results and are competitive with the Belle II prospects.