Paper Explainer: Two is not always better than one: Single Top Quarks and Dark Matter

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Paper Explainer: Two is not always better than one: Single Top Quarks and Dark Matter

A few months ago, I was lucky enough to be contacted by an experimental student in the CMS collaboration, Deborah Pinna. Deborah had a question for me: in a certain set of dark matter models that I had written one of the early papers on, we only considered one particular class of final states, namely production of dark matter at the LHC along with a pair of top quarks. Why, she asked, did we not also consider the production of a single top quark, along with dark matter?

The answer was that everyone, including myself, just assumed that this channel didn’t matter. I’ll explain why in a bit, but I had just assumed that the rate at which this sort of event could occur would be so low that I never actually bothered to check. It turned out that my intuition was wrong. Deborah did check, and upon finding out that this single-top channel mattered, contacted me, assuming perhaps there was a good reason for ignoring it. There wasn’t.

I was really happy to contribute to Deborah’s project, and I want to emphasize that she and a postdoc, Alberto Zucchetta, did all of the heavy lifting on this paper.

So what was the idea? What is single versus pair production of tops, and why does it matter?

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Paper Explainer: Precision Corrections to Fine Tuning in SUSY

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Paper Explainer: Precision Corrections to Fine Tuning in SUSY

This paper is part of a pair with the paper I wrote about here. We were interested in determining how constrained a particular theoretical extension of the Standard Model, supersymmetry (or "SUSY") is by the present experimental results (as of this last summer's ICHEP meeting). The previous paper was the "phenomenology" paper: we took the experimental results, reinterpreted them in the context of a number of interesting models, and calculated the amount of "tuning" that would be present in each model.

The paper we just put out is more of the "theory" paper, the paper that outlines how we did the tuning calculations we used in the phenomenology paper. The results are somewhat technical, so I will spend a bit more time describing the problem in general, and then talk in broad terms about what this paper adds to the discussion. So first I should describe a bit what we mean by "tuning," and why theoretical physicists care so much about it.

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Recent Paper: Narrow or Wide? The Phenomenology of 750 GeV Diphotons

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Recent Paper: Narrow or Wide? The Phenomenology of 750 GeV Diphotons

Pretty much everything I know now about the anomaly at 750 GeV.  Read this, and you'll know it too. It’s nothing too certain, but I expected that going in. 3.6σand 2.6σ is just not that much significance to start with, so any question I ask would have conflicting and uncertain results, with at best only minor preferences for any particular result. But I internalized a lot about the experimental results by forcing myself to grind through the data, and once you’ve done that much work it seemed silly not to write a paper about it.

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Diphotons at 750 GeV

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Diphotons at 750 GeV

Yesterday was the first data release of the LHC Run-II, and there has been a lot of interest in the first hints of something new. I’m skeptical, and wishing for more data. There are some suspicious tensions with previous results, but it’s certainly not clearly wrong, and its definitely the most intriguing sign of something new since the Higgs discovery. Unfortunately, we’ll have to wait at least a year to get more data to directly speak to this anomaly. It will be a difficult wait. But while we wait, read this to find out more of what we're looking at.

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