Search for the direct production of charginos and neutralinos in final states with tau leptons in ^√s = 13 TeV pp collisions with the ATLAS detector

A search for the direct production of charginos and neutralinos in final states with at least two hadronically decaying tau leptons is presented. The analysis uses a dataset of pp collisions corresponding to an integrated luminosity of 36.1 fb⁻¹, recorded with the ATLAS detector at the Large Hadron Collider at a centre-of-mass energy of 13 TeV. No significant deviation from the expected Standard Model background is observed. Limits are derived in scenarios of ^{χ̃ +}₁^{χ̃ −}₁ pair production and of ^{χ̃ ±}₁^{χ̃ 0}₂ and ^{χ̃ +}₁^{χ̃ −}₁ production in simplified models where the neutralinos and charginos decay solely via intermediate left-handed staus and tau sneutrinos, and the mass of the τ̃_L state is set to be halfway between the masses of the ^{χ̃ ±}₁ and the ^{χ̃ 0}₁. Chargino masses up to 630 GeV are excluded at 95% confidence level in the scenario of direct production of ^{χ̃ +}₁^{χ̃ −}₁ for a massless ^{χ̃ 0}₁. Common ^{χ̃ ±}₁ and ^{χ̃ 0}₂ masses up to 760 GeV are excluded in the case of production of ^{χ̃ ±}₁^{χ̃ 0}₂ and ^{χ̃ +}₁^{χ̃ −}₁ assuming a massless ^{χ̃ 0}₁. Exclusion limits for additional benchmark scenarios with large and small mass-splitting between the ^{χ̃ ±}₁ and the ^{χ̃ 0}₁ are also studied by varying the τ̃_L mass between the masses of the ^{χ̃ ±}₁ and the ^{χ̃ 0}₁.