I'm at Fermilab for an LPC (LHC Physics Center) workshop on new ideas for LHC dark matter searches. I have been working with my fellow professor David Shih, postdocs Anthony DiFranzo and Angelo Monteux, and grad student Pouya Asadi at Rutgers on new ways to look for interesting anomalies in LHC data (see our paper and my blog post about it). Though not specifically about dark matter, it is a new idea, and so I have a talk about it. Here are the slides.Read More
I'm up in Laurentian University in Sudbury, Ontario, giving three hours of lectures on "Beyond the Standard Model physics and the LHC" for the TRISEP Summer School.
TRISEP this year is mostly experimental grad students, and mostly experimental grad students working on experiments in the underground labs (such as SNOLAB in Sudbury). I'm the only lecturer who's talking about Beyond the Standard Model physics in general (though specific topics like dark matter and neutrino physics are being covered in more detail by other lecturers), and the only one talking about the LHC. Given that, and the audience, I ended up giving a broad overview: first on the sort of things we theorists have reason to think must exist beyond the Standard Model, then how the LHC works (always entertaining to have a theorist speak on how experiments work), and then lastly on how we look for new physics at the LHC. The slides are below.Read More
Is there any new physics at the LHC?
The answer appears to be “no.” If there was obvious evidence of new physics at the LHC, trust me, you would have heard about it by now.
But how do we know? The LHC produces a truly ridiculous amount of data. For each event (and the LHC writes to permanent record 400 events per second) the LHC records all information from all the detector elements. But nowhere in that information is a little flag that says “New Physics!” Indeed, most new physics we can imagine can be aped by physics of the Standard Model. We look for new physics via statistical evidence: we hope to see more events with a particular character than we would have expected.
But we haven’t seen such an excess, correct?Read More
I'm here at UC Irvine at the DM@LHC 2017 conference (that's "Dark Matter at the Large Hadron Collider"), and was asked to give a talk for a "Theory Overview of Dark Matter Searches." That's a big topic to get through in 30 minutes, so this is what I came up with.Read More
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?Read More
This is a blog post on my most recent paper, written with my fellow Rutgers professor David Shih, a Rutgers NHETC postdoc Angelo Monteux, and two Rutgers theory grad students: David Feld (my student) and Sebastian Macaluso (David’s student). It was a pretty big project, as the large (for a theory paper) author list indicates, and in fact the end result was split into two papers for publication, with the 2nd paper coming along shortly.Read More
I was asked to give a talk at the 2016 TOP Conference in Olomouc, Czech Republic. The TOP Conference is, as the name implies, a conference about the top quark. It was mostly experimentalists, with only a few theorists. I was asked to talk about possible connections between the top quark and dark matter. Since there weren't many theorists, I decided to give a relatively broad overview of the topic, rather than drilling down on one particular paper of mine. Here's the talk as I gave it.Read More
This week is the ICHEP2016 meeting in Chicago, which serves as one of the major summer conferences where experiments release their accumulated results. One of the most anticipated results this year was the update on the diphoton anomaly which was found in ATLAS and CMS data collected last year in the first bit of 13 TeV data from the LHC.Read More
I'm at a workshop (hosted by the theorists at U Oregon in Eugene) on recent LHC anomalies, most notably the diphoton excess of which there has been so much noise of late. I was fortunate enough to be asked to give the opening talk, showing my theorist-level fits to the CMS and ATLAS diphoton data. I thought it might be nice to put the slides I used up here. Enjoy.Read More
Here, I describe a recent paper I wrote with a group of experimentalists (Jim Brooke, Patrick Dunne, Bjoern Penning, and Miha Zgubic) and a Rutgers undergrad, John Tamanas. We investigated the ability of the Large Hadron Collider (LHC) to find dark matter using a particular type of event, one called “vector boson fusion,” or VBF.Read More
The first part of this is a non-specialist description of the results of Moriond concerning the diphoton anomaly. About halfway through it will transition into a more technical discussion, including new plots I've made giving my theorist-level combinations of the data shown.Read More
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.Read More
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.Read More
I'm going to describe my most recent paper, written with my now-frequent collaborator, Dorival Gonçalves, postdoc at the IPPP at Durham University. This paper is closely related to Dorival and my previous paper together, which I wrote about here. In fact, this was the project we were working on when we realized what we were doing had application to Higgs physics. When that happened, we decided to drop what we were currently working on and rush out the Higgs-related paper. Then we returned to the original idea, which was to find ways to study dark matter production at the LHC.Read More
In this post, I'll talk about my recent paper, written with my graduate student, David Feld.
This paper is interested in leptophilic Higgs models, and their possible connection to dark matter. I'll explain what those are in a bit. Such models have been considered before, but looking around at the literature, we didn't see a lot that had been updated after the discovery in 2012 of the Higgs boson at 125 GeV. We wanted to see what changed once we folded these new results in to the mix.Read More
I'm going to describe my most recent paper, written with Dorival Gonçalves, postdoc at the IPPP at Durham University. This is the arXiv version, as is usual in particle physics, we submit to the preprint serve, collect up commentary and citation requests, then get around to submitting to a journal.Read More
...physicists discovered that the uranium atom was really large; at least as far as incredibly microscopic objects go. Everything they threw at it seemed to "hit," so the nucleus was "as big as a barn."Read More