<p>We study SU(<i>N</i>) super Yang-Mills theory with a small gaugino mass <i>m</i> and vacuum angle <i>θ</i> on the four-torus <InlineEquation ID="IEq2"> <EquationSource Format="MATHML"><math display="inline"> <msup> <mi mathvariant="double-struck">T</mi> <mn>4</mn> </msup> </math></EquationSource> <EquationSource Format="TEX">\( {\mathbbm{T}}^4 \)</EquationSource> </InlineEquation> with ’t Hooft twisted boundary conditions. Introducing a detuning parameter ∆, which measures the deviation from an exactly self-dual <InlineEquation ID="IEq3"> <EquationSource Format="MATHML"><math display="inline"> <msup> <mi mathvariant="double-struck">T</mi> <mn>4</mn> </msup> </math></EquationSource> <EquationSource Format="TEX">\( {\mathbbm{T}}^4 \)</EquationSource> </InlineEquation>, and working in the limits <i>mLN</i> ≪ Λ<i>LN</i> ≪ 1 and <InlineEquation ID="IEq4"> <EquationSource Format="MATHML"><math display="inline"> <mfrac> <mrow> <mfenced close=")" open="("> <mrow> <mi>N</mi> <mo>−</mo> <mn>1</mn> </mrow> </mfenced> <msup> <mi>m</mi> <mn>2</mn> </msup> <msup> <mi>L</mi> <mn>2</mn> </msup> </mrow> <mrow> <mn>4</mn> <mi>π</mi> </mrow> </mfrac> <mo>≪</mo> <mtext>∆</mtext> <mo>≪</mo> <mn>1</mn> </math></EquationSource> <EquationSource Format="TEX">\( \frac{\left(N-1\right){m}^2{L}^2}{4\pi}\ll \Delta \ll 1 \)</EquationSource> </InlineEquation>, where <i>L</i> is the torus size and Λ the strong-coupling scale, we compute the scalar and pseudo-scalar condensates to leading order in <i>m</i><sup>2</sup><i>L</i><sup>2</sup>/∆. The twists generate fractional-charge instantons, and we show that summing over all such contributions is crucial for reproducing the correct physical observables in the decompactified strong-coupling regime. From a Hamiltonian perspective, the sum over twisted sectors, already at small torus size, projects in the <i>m</i> = 0 limit onto a definite superselection sector of the <i>ℝ</i><sup>4</sup> theory. In the massless limit, we recover the exact value of the gaugino condensate |〈<i>λλ</i>〉| = 16<i>π</i><sup>2</sup>Λ<sup>3</sup>, and demonstrate how a spurious U(1) symmetry eliminates all <InlineEquation ID="IEq5"> <EquationSource Format="MATHML"><math display="inline"> <mi mathvariant="script">CP</mi> </math></EquationSource> <EquationSource Format="TEX">\( \mathcal{CP} \)</EquationSource> </InlineEquation>-violating effects. Our results are directly testable in lattice simulations, and our method extends naturally to non-supersymmetric gauge theories.</p>

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Mass-deformed super Yang-Mills theory on \( {\mathbbm{T}}^4 \): sum over twisted sectors, θ-angle, and CP violation

  • Mohamed M. Anber,
  • Erich Poppitz

摘要

We study SU(N) super Yang-Mills theory with a small gaugino mass m and vacuum angle θ on the four-torus T 4 \( {\mathbbm{T}}^4 \) with ’t Hooft twisted boundary conditions. Introducing a detuning parameter ∆, which measures the deviation from an exactly self-dual T 4 \( {\mathbbm{T}}^4 \) , and working in the limits mLN ≪ ΛLN ≪ 1 and N 1 m 2 L 2 4 π 1 \( \frac{\left(N-1\right){m}^2{L}^2}{4\pi}\ll \Delta \ll 1 \) , where L is the torus size and Λ the strong-coupling scale, we compute the scalar and pseudo-scalar condensates to leading order in m2L2/∆. The twists generate fractional-charge instantons, and we show that summing over all such contributions is crucial for reproducing the correct physical observables in the decompactified strong-coupling regime. From a Hamiltonian perspective, the sum over twisted sectors, already at small torus size, projects in the m = 0 limit onto a definite superselection sector of the 4 theory. In the massless limit, we recover the exact value of the gaugino condensate |〈λλ〉| = 16π2Λ3, and demonstrate how a spurious U(1) symmetry eliminates all CP \( \mathcal{CP} \) -violating effects. Our results are directly testable in lattice simulations, and our method extends naturally to non-supersymmetric gauge theories.