The LHC Higgs Boson Hunter : Discovery News


IM Interview: Prof. Butterworth, a physicist using the ATLAS detector, hopes the Large Hadron Collider will reveal more exotic physics than just the Higgs.

Professor Jonathan Butterworth is an experimental particle physicist at University College London (UCL), and a member of the ATLAS collaboration at the Large Hadron Collider (LHC).

As his team prepares for the re-start of the most complex experiment mankind has ever conceived, Discovery News producer Ian O'Neill manages to catch Prof. Butterworth between TV interviews to chat about micro-black holes, spin-off technologies and why he's not a big fan of the Higgs boson.

You can follow Prof. Butterworth's work on the frontier of accelerator physics in a series of short films called "Colliding Particles -- Hunting the Higgs."

Ian O'Neill: Hi Jon. Just grabbing a coffee refill.

Prof. Jon Butterworth: Now that would have been a good plan...

Ian: I'm usually an Earl Gray tea fan, but I've spent so much time in the US I've been converted.

Thank you so much for taking the time to speak with me, you must be getting busy! Are you getting lots of interview requests?

Jon: They seem to be starting up again yes. Not quite as hectic as last year (yet) but people do seem to be still interested...

Ian: That's good -- last year was crazy. I was blogging about the LHC every day and some of the theories flying around were ridiculous. It's been nice to have a "quieter" time on the second attempt.

So is this weekend looking likely for the first proton circulation?

Jon: Seems that way, yes. Everyone's being very careful not to add to the pressure -- the main thing is to do it, not to meet an arbitrary schedule. But currently looks like ATLAS will see its first beam events of the year sometime over the weekend. We are the last in line around the LHC, so once the beam gets to us; it has done the full 27km from injection.

Ian: Wow. So when this is completed, we'll be back at "square one"; basically the stage we were at last year before the LHC quench?

Jon: Yep. They had stored & captured the beams (meaning they were sending the same protons round lots of times) just before things went wrong. After that were into new territory.

Ian: This is great news. And this time I understand a new "early warning system" has been put into place to prevent any further quenches?

Jon: Yes, there's been a lot of work on protection systems. Not just to try and prevent them happening, but to make sure that if they do happen they can't cause such damage. Any big cryogenic system will see quenches (they get them at Fermilab all the time) but there is no way it should zap 40 magnets -- at worst it should be a minor delay. I think a lot of people thought the tension was a bit fake last year. Hopefully one benefit of the accident is that at least people realize it really is a new thing we're doing. All these nervous physicists on TV weren't nervous about being on TV, they were worried the LHC (or the detectors) might fail!

Ian: I can imagine. This is one of the things I keep reminding people, the LHC is the most complex experiment mankind has ever constructed, I'm surprised there aren't more problems! It's not like one can build a prototype, the LHC IS the prototype!

Jon: Yep -- Lynn Evan's most famous quote apart from "1... 2... 3... nothing happens.. yes, there it is!"

And of course we're sweating that our detectors can actually see the data. Would be pretty poor if the LHC gave us collisions and we missed 'em.

Ian: Lynn Evans is a great character. I used to study in Wales, so it's nice to hear the Welsh accent at LHC press conferences.

So your work focuses on the ATLAS detector, what's your key research interest? Is it the hunt for the Higgs, or something more exotic?

Jon: Well, we're always keeping an eye out for exotica, but my main interest is the Higgs. Actually I am not really a big Higgs fan, but something has to be doing the job of making the electromagnetic force look so different from the weak force at everyday energies. We know at higher energies they look much more similar, and the difference is the mass of the force carriers. If it's not the Higgs doing it, it is something more exotic, and our theories are wrong. That would be exciting.

But the bottom line is, ATLAS will either find the Higgs, or prove that it's not there and the "Standard Model" is wrong.

Ian: So this is pretty much the End Game of the Standard Model? I was reading that a lot of other physicists don't want to find the Higgs either. If ATLAS doesn't find old Higgsy, what does that mean for physics? Do we have to start re-writing the text books?

Jon: We don't utterly bin the standard model, because it works amazingly well as energies below the LHC. But it means it has to be part of some bigger, better theory. It's very like Newton and Einstein... relativity contains Newtonian mechanics as an approximation at low speeds. Newton's stuff still works unless you start travelling at a substantial fraction of the speed of light. So the standard model will still be fine for doing most atomic and nuclear physics, and for doing most particle physics below LHC energies. But we'll have to learn new stuff for higher energies.

Ian: Very true, besides, I've sat through way too many quantum physics lectures, I don't think I could face being told that it's not quite the way nature works!

So the Standard Model is a great general model, but if we find no evidence for the Higgs boson, what would be the next step?

Jon: It really depends what else we do find. There are things which can happen at the LHC for which we have no prediction if the Higgs isn't around. The production of pairs of W and Z particles gives nonsense results with no Higgs. Since nature won't be nonsense, that's one of the best places to look for clues as to what the real physics is that is responsible for mass and for breaking the weak force from the electromagnetic one.

As an experimentalist it would be great to be ahead of the theory again. We might see weird bumps, extra dimensions, who knows? Though I bet some would be able to explain it as supersymmetry.

Ian: Supersymmetry fascinates me. So do extra dimensions. In fact, I've written a fair bit about the search for extra dimensions, but how would a detector like ATLAS go about detecting them? Is this where the micro-black holes come in?

Jon: that's one of the possibilities yes. There are various theories where gravity operates in more (tiny or warped) dimensions than the other forces. So once you have enough energy to be able to see these extra dimensions, you can either get mini black holes, or sometimes resonances -- bumps in the distributions -- coming from gravitons or other strange stuff. I wouldn't bet the farm on it, but it's intriguing because we really are going into a new regime and something new lives there, even if it is "only" the Higgs.

Ian: This is certainly the frontier of physics you are working on. Do you wake up in the morning and pinch yourself? Just in case you're in a physicist's dream?

Jon: Or nightmare, if it blows up again! Yes, I feel very privileged to be doing what I'm doing actually. When I was 10 years old, if I'd known I'd be doing this when I grew up I would have been so chuffed. The thought keeps me going through some very long meetings...

If I ever did grow up, of course...

Ian: And I bet you never dreamed you'd be looking out for tiny black holes! I'm thrilled that we might be able to detect them, what would be a tell-tale sign in ATLAS if a micro-black hole is generated? After all, you'd have to be quick; they're not predicted to hang around very long are they?

Jon: That's right. They would decay very quickly by Hawking radiation. So we'd look for the products of those decays. They look a lot busier than a "normal" event.

Ian: Wouldn't there be a loss of energy? Will it have, in effect, been lost to an extra dimension?

Jon: That can happen in some extra-dimension models. Essentially gravitons can head off at right angles to reality, and we can maybe spot the imbalance in energy that causes. But I think most of the black holes just decay to stuff we know about, in the dimensions we know about. If they are there in the first place, of course.

Ian: Brilliant. The second you see a black hole signature, be sure to give me a call before anyone else!

Jon: Well, I'd have to get it cleared by the ATLAS collaboration first, but after that, you'll be the first I tell, I promise.

Ian: Awesome.

Jon: My little boy is reading over my shoulder. He says "hi"

Ian: Finally, I really wanted to find out what you think will be the legacy of the LHC. After all, the discovery (or, even better, non-discovery) of the Higgs would revolutionize our understanding of the Universe, but would this lead to bigger accelerators? Or is the LHC the limit we are prepared to go to?

Say hi to your son for me! How old is he?

Jon: He's 7 :)

I think there's a planning blight on future facilities until we know what we find with the LHC. There are plans to upgrade it a bit, and there are discussions about linear colliders for electrons, muon colliders (they are discussing that at Fermilab today I believe) and even bigger hadron colliders. Which is most suited to the physics depends My opinion is that LHC is about as far as we can push current technology. So the challenge is to develop ways of continuing our "quest" without just digging bigger tunnels and spending more money. This is always cool because the technologies we need (e.g. the superconducting cryogenics, the detector or the www) usually have lots of other uses too. Accelerator technologies are very exciting, and we need to do some work and have some good ideas there to be able to build something better than LHC but not necessarily bigger.

Ian: Wonderful. That's another aspect that thrills me more than what the LHC might discover -- the spin-off technology literally changes the way we live our lives. You sure have an important job!

Jon: Good of you to say so. I also think that the impact the LHC has on people's view of science and technology, the way these questions can stimulate our ingenuity and imagination in a very broad sense, is a vital thing to share. So you have a very important job too there - back at you.

Ian: Well, if I can help you guys who are on the forefront of discovery to communicate the mind-blowing science you are doing, it makes me very happy. You do the hard work and I'll write about your adventures. Works for me. Thank you so much for taking the time to speak with me Jon. Good luck with all your research (and remember, you see a micro-black hole, call me) ;)

Jon: me too - I have students to do the tricky bits. It's been a pleasure. Will do. All the best, & bye now.