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
I am organizing a March for Science in Trenton, this April 22. I hope that you’ll join me there, or join one of the many other marches happening that day, around the world. As someone organizing a march, I feel it necessary to explain why I am marching: why I feel it necessary to stand up and defend science.Read More
“Keep science out of politics.”
This is the refrain I’ve been hearing a lot recently, both from scientists and non-scientists. On April 22, 2017, scientists and science-lovers around the country are planning a March for Science in DC, to protest the silencing of government scientists, the removal of scientific input into the political decision-making process, the impact of travel and immigration restrictions on the scientific and student community, and to bring attention to the climate change crisis. Given that one party has been pushing these policies (or, in the case of climate change, has been pushing to avoid setting any policy that could address the problem), this march inevitably has become embroiled in partisan politics.
This has opened a serious and important debate among scientists about the propriety and sense of marching as scientists, for political goals. Shouldn’t we keep politics out of science, and by extension, science out of politics?Read More
Relativity is profoundly unintuitive to humans. Our brain seem hardwired to visualize geometry in at most 3 dimensions, and 3 Euclidean dimensions at that. This is probably because we evolved in an environment where objects move at non-relativistic speeds. Similarly since we evolved in an environment where actions were much larger than the Planck constant, our brains just do not think naturally in terms of quantum mechanics. We are, at our core, creatures who think in classical physics. And that is good enough if you're a naked ape looking to hit a gnu with a rock, or even an engineer building the Hoover Dam, but that physical intuition falls apart when you get to the physics of the very fast, the very big, or the very small. And since the Universe is really quantum and relativistic, those limits are where things get fun.
Let's look at one of those fun things: the Twin Paradox. First in Special Relativity, and then again in General Relativity.Read More
“I am, somehow, less interested in the weight and convolutions of Einstein’s brain than in the near certainty that people of equal talent have lived and died in cotton fields and sweatshops.” -- Stephen J. GouldRead 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 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.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
In science fiction, it is pretty standard fare to introduce some form of faster-than-light communication or travel. After all, space is big, and you can't write your swashbuckling Hornblower-in-space novel if you have to wait for a generation ship to crawl painfully slowly between the nearest stars, much less try to cross a galaxy.
However, faster-than-light communication (which includes travel) breaks something very fundamental about physics, something that is often ignored by sci-fi, and difficult for non-physicists to understand. If you allow faster-than-light (FTL), then you break causality: you are allowing time-travel.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
Its an interesting challenge to explain physics using twitter. Working with ideas than can be chopped up to 140 character chunks really focuses you. Magnets are complicated things, but this should give you an idea.Read More
I want to talk a little about the central idea that led Einstein to the concept of General Relativity. To get there, I want you to perform a little experiment.
Take a moment to think carefully about the forces you feel on yourself right now. If you’re sitting, you feel the chair pushing on your back, which pushes on the rest of your body. You feel the floor pushing your feet up. You might feel the muscles and tendons in your shoulder holding your arm up, or strain your neck holding your head up.
But do you feel the force of gravity?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