A major HEP conference, ICHEP 2008, is taking place in Philadelphia at the moment, and many of the talks are already available online here. This is mostly a conference devoted to experimental HEP, and the big news is the joint announcement by CDF and D0 that they are just barely able to exclude, at 95% confidence level, the possibility of a Higgs with mass of 170 GeV. This is the first new information about (ignoring neutrinos…) the one remaining parameter of the Standard Model since LEP showed that the Higgs mass can’t be below 115 Gev. For more about this, see Sunday’s ICHEP plenary talk by Matthew Herndon.
Also announced at ICHEP and providing constraints on the possible Higgs mass are new fits using precision electroweak measurements. Tommaso Dorigo has a nice explanation of this story in a new posting here. Don’t miss the comment section, which has a hilarious exchange between Lubos and an anonymous physicist who can’t believe what is going on, asking Tommaso to check IP addresses to see if someone is impersonating Lubos. The point of physics being discussed is an extremely interesting one, but the mode of discussion ensures that enlightenment will not result.
Lyn Evans of the LHC gave a report on its progress. They expect to first try to inject a beam about a month from now, with first collisions and data maybe two months later, at 10 GeV center of mass energy. Evans is guessing that luminosity in 2008 will be about 10 pb-1.
This morning, Joe Polchinski will give the plenary talk on “Recent Progress in Formal Theory”, and Witten gave a public lecture Monday night. Nima Arkani-Hamed was supposed to give a “Concluding Inspirational Talk”, but that appears to have been canceled.
Update: It’s worth noting that the Higgs mass getting excluded is right in the middle of where Alain Connes’s prediction from his NCG model comes in. Connes has a new blog posting about this here, where he admirably notes how discouraging this is for his model. Jacques Distler has a quite good new posting about the NCG model here.
More about this from Gordon Watts here.
Thanks for the link to Tommaso’s blog.
I must say that I have not been able to gather the verdict on the debate between Lubos and Guess Who. Does the experimental data that Tommaso presents constrain any effective Higgs that does the job of electroweak breaking? Or does it assume certain classes of models for Higgs (like simple SM Higgs or MSSM Higgs doublet)? Lubos seems to be arguing for the former while Guess Who seems to be arguing for the latter (specifically, that technicolor models need to be dealt with separately).
Much as I would hate teaming up with Lubosian lunacy, I must say that I find Guess Who’s claim suspicious, and if true, something of a letdown – I was hoping that those curves were “really” constraining the Higgs.
somebody,
Those curves are based upon a straightforward fit to the SM model, so they tell us where the Higgs is going to be found if we have just the SM, but I don’t see how they tell us in general about very different models. The argument about whether they “favor supersymmetry” just seems empty to me. As for whether Lubos or “Guess Who” knows more about what they are talking about here, that’s a point that doesn’t seem arguable at all…
A Russian Academician has leaked the inauguration date for the LHC: October 21st.
http://en.rian.ru/world/20080805/115771418.html
Peter,
This is off topic, but Sean over at Cosmic Variance has a very nice rundown on what the LHC is likely to find, and not find, here.
DB,
I thought that date had been public knowledge for quite a while. Those here who predicted that CERN would do everything it could (including lowering the energy of the beams) to get beams in the machine by the inauguration date were on the money.
Peter wrote:
Of exactly 170 GeV? I think I can exclude that with 95% confidence without even doing any experiments. 🙂
Of less than 170 GeV?
Within some range of 170 GeV?
John,
What is being excluded at 95% confidence level is some small mass range about 170 GeV. The experiments don’t quote a range, and it appears to me that this is because, however they have binned their data, they are just able to get above the 95% confidence level at one bin, that at 170 GeV. Under the circumstances, quoting any particular small range about 170 GeV wouldn’t be very meaningful.
A Russian Academician has leaked the inauguration date for the LHC: October 21st.
I’m looking at this press release which says that the “first attempt to circulate a beam” will be september 10, and that they’re this weekend (this is apparently confirmed at uslhc.us) doing the first beam tests of any sort.
Does this information alter the Novosti article, or is it just describing something different? Is the idea that the “inauguration” on Oct. 21 the same as first physics collisions, and the september 10 event will be the first full-power full-circulation beam test?
Coin,
The October 21st event is a ceremony for dignitaries (including President Sarkozy I believe) that was planned long ago. It doesn’t correspond to any particular state of progress of getting the machine into operation.
Thanks!
Dear Mr Woit
Do you know how I cd get hold of a copy of Witten’s public lecture at ICHEP08?
(Thanks v much for your v good blog.)
DC