Tuesday, 30 October 2007

Higgs in the blogsphere

In January a blogger, John Conway, who works on CDF at the Fermilabs Tevatron collider posted about a 2 sigma bump that may, or may not be the Higgs.
This is really interesting to me, not only because it may be the first observation of the Higgs, but because it was reported in the blogsphere. Most people still believe that scientific discoveries occur in a "Eureka" moment, but that is not the case. By sharing the story as a blog the method by which scientists arrive at the truth is also shared something that many people, among them the well educated, have no sense of whatsoever.
Another recent story which illustrates this point well is the story of Pentaquarks, which I have been part of in a very small way.
Pentaquarks particles made up of 4 quarks and and anti-quark, if this means nothing to you then think of them as like protons and neutrons but heavier, and not stable. they decay almost immediately into other particles. In the 60s people kept finding new particles and they were all classified as mesons (a quark and an anti-quark) or baryons (three quarks) but no other combinations were found. Which is odd, if you think of the elements, they are made by putting in more protons and electrons so Hydrogen is a proton with an electron, Helium is 2 protons, 2 neutrons and 2 electrons and so on. But the baryons and mesons just have 3 or 2 constituent particles. Furthermore, the underlying mathematical theory (QCD) of these composite particles, as we understand it at present, allows not only pentaquarks, but all kinds of other things, but so far we see no evidence of them.
Inspired by some new theoretical predictions the LEPS collaboration at SPring-8 in Japan looked for these pentaquarks and observed a small but statistically significant signal, they were closely followed by the DIANA collaboration and others. However some experiments looked and did not see any evidence for this new particle, and gradually, throughout 2005 the negatives overtook the positives. One particular experiment, which had seen the pentaquark signal looked again using more data specifically gathered to look for the pentaquark, but could not reproduce their earlier 5.5 and 7.8 sigma results.
It may look like the question is answered but this is not yet the case, DIANA published further evidence in 2006 for the pentaquark, althought this is the only recent positive evidence. It seems so incredibly unlikely that so many different experiments would see such similar (although in some cases not similar enough!) results and that it is a statistical fluctuation in each, but I am aware that there can be problems with reflections (seeing ghosts of other particles) in these particular cases, although I don't know the details, also, all the positives were small statistics experiments and it has been argued that the significance was overestimated.
A further important point is that even if it turns out that there is no narrow pentaquark it does not mean that the work done has no value, the pentaquark has reinvigorated the field of hadron spectroscopy and inspired new theoretical work into bonding between quarks in bound states to name just two important side-effects.
It illustrates well how science works, it is not a clear path to the truth followed by infallible, objective automatons. It also makes me quite pessimistic about the 2 sigma bumps seen by CDF, it seems to me they're in a good situation though, although there is excitement they have been careful enough and issued enough warnings that should it disappear with more statistics it will not look at all bad for them, and if it is something interesting and LHC then see something at the same mass then they will have seen the Higgs first.

France, Germany and back to France

My job would be so good for someone who loves travelling, unfortunately I don't particularly enjoy it, so this last month has been a bit hard. Having said that the trip to Paris proved to be really enjoyable. I had enough free time to look around and the meeting I was at was really interesting and I didn't have to worry about speaking myself.
The trip to Hamburg was quite the opposite. I was so busy I hardly got any time to myself, I had a talk to work on and I was really quite worried about it. It was the first talk I have given since maternity leave, and to make it even worse, the last time I went to give a talk I ended up in hospital (I was quite pregnant at the time)
Anyway it went ok, the first half was ok the second half was not so good, I underestimated my audience a bit, but there were some questions and some people seemed really interested. Anyway the whole trip really tireed me so I was really glad that we had planned a holiday immediately afterwards. In fact I had just 12 hours at home and we left to get the ferry to Boulogne.
We had planned to camp near Boulogne and drive to my brothers near Poitiers the next day. I know it sounds mad to camp in October, but we had a very good reason. We are planning a 9 month to a years holiday, where we are going to travel around the mediterranean and some of eastern europe, next year. So we need to know how much cold we can handle. So this was supposed to be our first rehearsal and it didn't go very well.
Things started to go a bit wrong when the ferry was an hour late so we arrived in Boulogne at 8 instead of 7, but we started off and found the campsite (despite K forgetting to bring the name or number for the campsite) we were pretty tired when we got there and the boys were quite whingy, also it was dark, really dark! The campsite looked really nice though and the couple were friendly so we paid and chose our pitch and went to put up the tent. We were really fast at putting up the tent, but the boys were getting really cross and the eldest was trying to help, we had nearly got it up after 10 minutes, the baby was really crying, I was cold and cross and the eldest was being a real pain in the ass. Anyway I went to get the pegs... they were not there :-( still we tried to manage with the 8 oegs we could find around the place trying to hammer them in with a stone (also forgot the hammer, baby flat out screaming by now) then came the blow up matress. Well we ran into 2 problems then, it was too big for the tent and we had no electricity to blow it up with anyway. So we gave up. We were incredibly cross and I was growling horribly at the eldest who was being a real pain becuase he doesn't like the sound of the youngest crying. It was really as bad as it could be. We drove back to Boulogne and stayed in an F1, which was 10 euros more than the campsite (who had reimbursed me!)
The rest of the hoiday was significantly better, walks and the zoo at Doue, the market, and seeing my brother I really love the Vienne, I think I would rather we move there than the south, it is so beautiful and sort of familiar, whereas the south looks so foreign.
We didn't even try to camp on the way back, maybe we should try the back garden first!!