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<div style="direction: ltr;font-family: Tahoma;color: #000000;font-size: 10pt;">Hello all,
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<div>This week Friday we will be hosting our very own Evan Johnson for the High Energy seminar! Please join us and hear from Evan on his work with EFTs for resonant Wino dark matter! Please not this is no the typical time or room.</div>
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<div>Friday, April 13th, 2018</div>
<div>11:30am</div>
<div>M2035, Physics Research Building</div>
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<div>Speaker: Evan Johnson</div>
<div>Title: Zero-Range Effective Field Theory for Resonant Wino Dark Matter</div>
<div><span style="font-family: Calibri, sans-serif; font-size: 14px; background-color: rgb(255, 255, 255);">Dark matter in the form of weakly interacting massive particles (WIMPs) with masses at the TeV scale receive nonperturbative “Sommerfeld enhancements”
to their pair annihilation rates due to unsuppressed exchanges of weak gauge bosons before the annihilation. These enhancements are conventionally computed numerically through the solution of coupled-channel Schrödinger equations. The most dramatic enhancements
occur when there is an S-wave resonance near the WIMP-pair threshold. My collaborators and I have developed an effective field theory for wino dark matter near such a resonance. Winos interact nonperturbatively through zero-range contact interactions as well
as through the long-range Coulomb interaction. Our analytic results for wino scattering and wino-pair annihilation accurately reproduce the results calculated numerically using the Schrödinger equation. I will show how this effective field theory is systematically
improvable, how the Coulomb resummation is carried out, and how to build in the annihilation processes. Finally, I will demonstrate the power of this effective field theory by showing how a complicated process, the formation of a WIMP-pair bound state, can
be calculated analytically.</span></div>
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<div><span style="font-family: Calibri, sans-serif; font-size: 14px; background-color: rgb(255, 255, 255);">-Brian</span></div>
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