Erich Poppitz

Leptophilic dark matter

We describe a simple model of dark matter, which explains the PAMELA/ATIC excesses while being consistent with all present constraints. The DAMA annual modulation signal can also be explained for some values of the parameters. The model consists of a dark sector containing a weakly coupled broken U(1) gauge symmetry, under which only the dark matter state and the leptons are charged.

Continuity, deconfinement, and (super) Yang-Mills theory

A bstractWe study the phase diagram of SU(2) Yang-Mills theory with one adjoint Weyl fermion on

Conformality or confinement: (IR)relevance of topological excitations

{{\mathbb{R}}^3}\times {{\mathbb{S}}^1}

R-symmetric gauge mediation

as a function of the fermion mass m and the compactification scale L. This theory reduces to thermal pure gauge theory as m → ∞ and to circle-compactified (non-thermal) supersymmetric gluodynamics in the limit m → 0. In the m-L plane, there is a line of center-symmetry changing phase transitions. In the limit m → ∞, this transition takes place at Lc = 1/Tc, where Tc is the critical temperature of the deconfinement transition in pure Yang-Mills theory. We show that near m = 0, the critical compactification scale Lc can be computed using semi-classical methods and that the transition is of second order. This suggests that the deconfining phase transition in pure Yang-Mills theory is continuously connected to a transition that can be studied at weak coupling. The center-symmetry changing phase transition arises from the competition of perturbative contributions and monopole-instantons that destabilize the center, and topological molecules (neutral bions) that stabilize the center. The contribution of molecules can be computed using supersymmetry in the limit m = 0, and via the Bogomolnyi-Zinn-Justin (BZJ) prescription in non-supersymmetric gauge theory. Finally, we also give a detailed discussion of an issue that has not received proper attention in the context of N = 1 theories — the non-cancellation of nonzero-mode determinants around supersymmetric BPS and KK monopole-instanton backgrounds on

Index Theorem for Topological Excitations on R^3 \times S^1 and Chern-Simons Theory

{{\mathbb{R}}^3}\times {{\mathbb{S}}^1}

Universal mechanism of (semi-classical) deconfinement and θ-dependence for all simple groups

. We explain why the non-cancellation is required for consistency with holomorphy and supersymmetry and perform an explicit calculation of the one-loop determinant ratio.

Seiberg-Witten and “Polyakov-like” magnetic bion confinements are continuously connected

What distinguishes two asymptotically-free non-abelian gauge theories on R4, one of which is just below the conformal window boundary and confines, while the other is slightly above the boundary and flows to an infrared conformal field theory? In this work, we aim to answer this question for non-supersymmetric Yang-Mills theories with fermions in arbitrary chiral or vectorlike representations. We use the presence or absence of mass gap for gauge fluctuations as an identifier of the infrared behavior. With the present-day understanding of such gauge theories, the mass gap for gauge fluctuations cannot be computed on R4. However, recent progress allows its non-perturbative computation on R3 × S1 by using either the twisted partition function or deformation theory, for a range of sizes of S1 depending on the theory. For small number of fermions, Nf, we show that the mass gap increases with increasing radius, due to the non-dilution of monopoles and bions — the topological excitations relevant for confinement on R3 × S1. For sufficiently large Nf, we show that the mass gap decreases with increasing radius. In a class of theories, we claim that the decompactification limit can be taken while remaining within the region of validity of semiclassical techniques, giving the first examples of semiclassically solvable Yang-Mills theories at any size S1. For general non-supersymmetric vectorlike or chiral theories, we conjecture that the change in the behavior of the mass gap on R3 × S1 as a function of the radius occurs near the lower boundary of the conformal window and give non-perturbative estimates of its value. For vectorlike theories, we compare our estimates of the conformal window with existing lattice results, truncations of the Schwinger-Dyson equations, NSVZ beta function-inspired estimates, and degree of freedom counting criteria. For multi-generation chiral gauge theories, to the best of our knowledge, our estimates of the conformal window are the only known ones.

Less naive about supersymmetric lattice quantum mechanics

We present a version of Gauge Mediated Supersymmetry Breaking which preserves an R-symmetry—the gauginos are Dirac particles, the A-terms are zero, and there are four Higgs doublets. This offers an alternative way for gauginos to acquire mass in the supersymmetry-breaking models of Intriligator, Seiberg, and Shih. We investigate the possibility of using R-symmetric gauge mediation to realize the spectrum and large sfermion mixing of the model of Kribs, Poppitz, and Weiner.

Lattice supersymmetry, superfields and renormalization

We derive an index theorem for the Dirac operator in the background of various topological excitations on an R{sup 3} x S{sup 1} geometry. The index theorem provides more refined data than the APS index for an instanton on R{sup 4} and reproduces it in decompactification limit. In the R{sup 3} limit, it reduces to the Callias index theorem. The index is expressed in terms of topological charge and the {eta}-invariant associated with the boundary Dirac operator. Neither topological charge nor {eta}-invariant is typically an integer, however, the non-integer parts cancel to give an integer-valued index. Our derivation is based on axial current non-conservation--an exact operator identity valid on any four-manifold--and on the existence of a center symmetric, or approximately center symmetric, boundary holonomy (Wilson line). We expect the index theorem to usefully apply to many physical systems of interest, such as low temperature (large S{sup 1}, confined) phases of gauge theories, center stabilized Yang-Mills theories with vector-like or chiral matter (at S{sup 1} of any size), and supersymmetric gauge theories with supersymmetry-preserving boundary conditions (also at any S{sup 1}). In QCD-like and chiral gauge theories, the index theorem should shed light into the nature of topological excitations responsible for chiral symmetry breaking and the generation of mass gap in the gauge sector. We also show that imposing chirally-twisted boundary condition in gauge theories with fermions induces a Chern-Simons term in the infrared. This suggests that some QCD-like gauge theories should possess components with a topological Chern-Simons phase in the small S{sup 1} regime.

Microscopic structure of magnetic bions

A bstractUsing the twisted partition function on