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March 04, 2005


Alejandro Rivero

Tommaso, there is never enough physics in the blogs. (And being myself a manager of the physcomments.org site, I can tell how true this is, regretly).

A question surely nobody will ask you in your presentation: Can you see some traces of the disappearing H+ scalar of hep-ex/9909044, hep-ex/0009010, hep-ex/0105057? Averaging more events put its sigmas back to fluctuation, but it still worries me.


Hey Tommaso,
well this was really hard to read. Not sure, if I understood much. However, this is the first time, I feel like it was too much physics.
Just some questions on my side: How long will this talk take? It looks pretty impressive, when I look at it in my browser.
The second thing, I am curious about, is there anything you don't know about the Higgs Boson except its mass? And maybe its existence?


Unfortunately my physics is too weak to understand...;-D

Tommaso Dorigo

Hi all, and thanks for trying to read through the post above!

Alejandro: I think the general agreement among the Physics community is that the signal was indeed a fluctuation. Besides, because of the way we analyze our data, these kinds of fluctuations are more likely to produce 3,4,5-sigma discrepancies than the absolute meaning of those figures would suggest. So worry not! However, we would have no sensitivity to that signal in proton-antiproton collisions, due to the huge QCD background.

Helge: thanks for your feedback! I am with you, the post above is too hard to digest. However, the audience of this site is composed in part by physicists (like Alejandro above :) and so I feel I can alternate easy and hard descriptions... As for the talk, I have 15'+5' to present it. I already know I can do it, although the slides do appear kind of thick. My style is to have on the slides more info than I am actually describing to the audience, because many will look at the slides but will not come to the talk. The Higgs boson: if it exists, and it is the standard model one, then we do know a lot about it, but we certainly need to measure those quantities that we know about, to make sure. We do not know its mass, and there might be other surprises behind the corner... One has to be alert.

Marco, thanks for the visit. As I explain above, not all my posts are for "general audience", but most are... But I think that the post is more "heavy" than "hard"...

Cheers to all,


Just to follow up. You write "if it exists, and it is the standard model one". So I wonder: Are there others?
Thanks for the reply.

Tommaso Dorigo

Hi Helge,

Thanks for your comment. Indeed, I was very quick in that sentence. The question is very important.

Yes, we are indeed not sure whether there is a Higgs boson (the one predicted in the Standard Model, SM), or if there is none (which is the most interesting case, since it would catch us with our pants down!), or if there are more than one! Actually, many believe that Supersymmetry (SUSY: a theory that modifies the SM to include a whole new series of particles, supersymmetric partners of all the particles so far known, quarks, leptons, and vector bosons alike) is the right theory of particle physics, since it has many a desirable feature, mending some shortcomings of the SM.

If SUSY is the theory, we do not know how many Higgs bosons we would see! But at the minimum, we would get FIVE of them. One of them would still behave quite similarly to the SM one, though, so in a sense finding a first Higgs boson would not allow us to immediately rule out one theory or another.

Maybe I should say a word or two about why the Higgs boson is important in the theory. Basically, it is called for by a property of space-time so important, one we cannot really do without: local gauge invariance.
If we are to both ensure that physical quantities which we expect to be conserved by the theory (think of the electric charge, for instance) do so in every point of space-time, that is locally, and not just at a global level, AND that the whole theory is consistent with other fundamental beliefs about the finiteness of the cross section of some particular processes, the easiest, cleanest way to do so is to introduce a Higgs boson in the theory.

I know the above is very fuzzy and unclear. Unfortunately, it takes about 5 years of courses in fundamental physics to really understand the whole thing!

Maybe I'll make a separate post of this later.


m. visaya

HTA big bang hall:

k = (2)*((t[a]*s+t[l]*b)/(t[c]*s+t[x]*b)) , (0

Day 0

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