Peter Higgs: My Life as a Boson
Just over a year ago, Professor Peter Higgs came to visit us in Stockholm to give the 2009 Oskar Klein lecture. I didn’t realise the lecture was recorded and available on the Stockholm physics website. This also reminded me that I’d recorded the audio of the talk on my phone and transcribed some of it on a flight back to Britain, so I dug it out.
It’s a great talk, and really worth watching if you’ve got an hour. Higgs came across as both brilliant and humble. He also noted that he’d given this talk a few times but that it was coming home to Sweden, being named after Lasse Hallström’s classic 80s film ‘Mitt liv som hund’.
My Life as a Boson
The story of my involvement begins in October 1960 when I was appointed to a lectureship at the University of Edinburgh. Really, it begins a little bit before because when I was appointed I was told that I had to join the committee of the first Scottish universities’ summer school in physics, which was happening that July. My job, which has some relevance to this story, was that of steward: essentially, to buy some wine, look after it and distribute it to the participants at dinner. That I did with rather limited success, as you will hear. The students at that school included three from Stockholm and four, whom I will refer to as the ‘Gang of Four’, whose names will be familiar to some of you: Nicola Cabibbo from Rome, Shelly Glashow who was based at CERN, Derek Robinson from Oxford and Martinus Veltman from Utrecht. These four stayed up half the night discussing theoretical physics of weak and EM interactions, and always missed the first lecture of the morning because they couldn’t get up in time.
On the Work Which Resulted in the Eponymous Boson
The following month I had the insight into how the Goldstone theorem could be evaded, but only if you had a gauge field theory. The insight really happened as a response to Gilbert’s work. It happened very quickly; it was roughly one week from my reading Gilbert’s paper—and being rather indignant that he seemed to have closed the door on the whole program—to my sending the paper for publication in Physics Letters.
I read the Gilbert paper on Thursday 16 July. Over the following week I realised that I knew a way out. The reason I knew the way out is that I’d been reading Julian Schwinger’s papers on the gauge invariance of the mass. Schwinger demolished a folklore of QED which said that the fact the photon has zero mass is a consequence of gauge invariance. He showed that it needn’t come from gauge theory.
I wrote a short paper which was published in Physics Letters, saying that coupling the system to a Maxwell-type gauge field is the answer. Once you’ve done that the necessary choice of gauge destroys the manifest covariance of the formalism without destroying the relativistic invariance of the physics. Somewhat to my surprise, it was accepted by the editor of Physics Letters at CERN.
By the following Friday I’d written a second paper. Once I’d realised what the way out was, the obvious thing to do was to write down the simplest possible model which incorporated a gauge field and make sure that the scalar fields in it spontaneously broke the symmetry—to see what happened. I did that during the week, and lo and behold the mass was generated for the photon length particle after all.
So, I sent that to Physics Letters and they rejected it. Well that, as you can imagine, surprised and upset me. They had accepted a paper which showed there is a way out of a theorem and rejected a paper which showed the consequences of the way out of that theorem, so I thought ‘well they don’t seem to understand what I’m talking about.’
On the Princeton Seminar
That experience was, I think, the most terrifying of my career. I was so terrified of the Institute that when the sign for Princeton turned up I had to pull off the freeway into a lay-by to stop trembling.
When I met Sidney Coleman years later in 1979, he recalled the Harvard Seminar: ‘Oh yes, we were looking forward to tearing to pieces this idiot who could get around the Goldstone theorem.’ But apparently that also went well enough for them to be convinced I wasn’t a fool. That was a conversation with the audience more than a seminar, but we never really got to the point of discussing what might be done with the Gauge theories involving spontaneous symmetry breaking, despite the fact that sitting in the audience was Shelly Glashow, one of the Gang of Four from our 1960 summer school. He came to me after the lecture and said “that’s a nice model you’ve got there Peter” but he didn’t think it had anything to do with his work on the electroweak unification in 1960 and ’61. He had the SU(2)-times-U(1) model already but with masses put in by hand, which spoilt the renormalisability of the quantum field theory. So why did I miss that?
Well, let me tell you something more about my efforts as a steward at the 1960 summer school. I’d been sent out and told how much money I could spend on wine in Edinburgh. I was responsible for conserving the wine, but the storage didn’t include a lock on my wine cupboard. So, as I discovered several years later when I met Cabibbo again, the Gang of Four were intent on non-conservation of my wine. And I learnt that my leaky wine store had fuelled their late night discussion of electroweak interactions. Of course, as I was the person supposed to conserve the wine they didn’t encourage me to join the party. So I didn’t learn of Glashow’s theory as early as I should’ve done.
On the Experimental Search for the Higgs
The years of LEP resulted in bounds of likely Higgs boson mass so that it is no longer something very vague—as it was when Ellis and the others wrote that paper. By 1995, it was less than 219 GeV with 95% confidence level. Of course in late 2000, when LEP was at the end of its run, some of the groups thought they’d seen something at about 115 GeV, but it later turned out the backgrounds were much worse than they had realised.
The story—since then until what we hope is going to happen in November—was really the starting up of the improved version of the Tevatron, which was really improved in the the way it was in order to search for the Higgs boson in the low mass range where there’d been something of a mismatch between the end of LEP and the beginning of the LHC…
Fermilab expect to have finished scanning the whole range down to where LEP finished by 2011, so the likely story for the future is that if it’s there—and some people think it won’t be there—it should be picked up by Fermilab in the next two years. I think with the delays which have happened with the LHC, LHC will be in the position of consolidation; that very likely Fermilab discovery will be very tentative.
