twistor59 wrote:Matt Strassler's article on the Higgs strategy

Since we’re now approaching the time when the preliminary results from December on the search for the Higgs particle at the Large Hadron Collider (LHC) will be presented in final form, possibly with small but important adjustments, and since there will be additional results based on the fall’s data in the next few weeks, it would be good to do a little review of where things stand and where they’re going.

HiggsSearch.png

Little Idiot wrote:

twistor59 wrote:Matt Strassler's article on the Higgs strategy

Since we’re now approaching the time when the preliminary results from December on the search for the Higgs particle at the Large Hadron Collider (LHC) will be presented in final form, possibly with small but important adjustments, and since there will be additional results based on the fall’s data in the next few weeks, it would be good to do a little review of where things stand and where they’re going.

HiggsSearch.png

From the lack of things to report, is it right to conclude they didnt get to find the Higgs yet?
How much not finding have they pinned down yet - i.e. how much of the possible range from the standard model has been (firmly?) excluded, and how much remains still a possibility?
Thanks for any update.

Do you have questions about the Higgs boson? Are you surprised by the idea of Supersymmetry? Do you wonder if our Universe is limited to three dimensions of space? Send us your questions in comments below and tell us why you would like to be a part of our Hangout.

twistor59 wrote:

Little Idiot wrote:

twistor59 wrote:Matt Strassler's article on the Higgs strategy

Since we’re now approaching the time when the preliminary results from December on the search for the Higgs particle at the Large Hadron Collider (LHC) will be presented in final form, possibly with small but important adjustments, and since there will be additional results based on the fall’s data in the next few weeks, it would be good to do a little review of where things stand and where they’re going.

HiggsSearch.png

From the lack of things to report, is it right to conclude they didnt get to find the Higgs yet?
How much not finding have they pinned down yet - i.e. how much of the possible range from the standard model has been (firmly?) excluded, and how much remains still a possibility?
Thanks for any update.

If you have a look at the Brazilian flag graph in this link, you'll get a picture of the latest summary (from the Atlas experiment), there are similar ones for the CMS experiment. Basically if the curves are below the straight line at a given value of MH, then that value of MH is excluded - the standard model Higgs does not have that mass. As far as I know, the "light" standard model Higgs mass range was 100 to 4(?)00 GeV (not sure exactly), so the only remaining part where there's a reasonable chance of finding it is 116-131 Gev (where the bump in the curve exists which pushes it above the straight line). That bump does not yet have enough statistical significance to claim a result - they need a lot more data which they will gather this year, so we'll have an answer by then.

If there's no light SM Higgs, I think there are still some heavier alternative models, but I'm not an expert on Higgs phenomenology so I don't know the details.

twistor59 wrote:... so the only remaining part where there's a reasonable chance of finding it is 116-131 Gev

lpetrich wrote:Someone has explored the implications of this putative discovery of the Higgs particle. [1112.3017] Implications of a 125 GeV Higgs scalar for LHC SUSY and neutralino dark matter searches
Howard Baer, Vernon Barger, Azar Mustafayev
(Submitted on 13 Dec 2011)

They analyzed it in two subsets of the Minimal Supersymmetric Standard Model:

mSUGRA: free parameters m0, m1/2, A0, tan(beta), sign(mu)
and
NUHM2: free parameters m0, m1/2, A0, tan(beta), mu, mA

m0 = mass scale of the spin-0 superpartners of the elementary fermions
m1/2 = mass scale of the spin-1/2 superpartners of the gauge particles
mA = mass scale of the heavy Higgs particles predicted by the MSSM

For both mSUGRA and NUHM2, m0 >~ 0.8 TeV, pushing the squark and slepton masses into the multi-TeV range. Those particles may thus be difficult to make with the LHC.

However, m1/2 is less constrained, meaning that the LHC may be able to make gluinos, neutralinos, and charginos more easily.

Both mSUGRA and NUHM2 tend to produce too much neutralino dark matter, except if the lightest neutralino is higgsino-like, with a mass around 0.8 TeV. However, that would bump the bino, wino, and gluino masses into the TeV range. Especially the gluinos, which are otherwise the easiest for the LHC to make.

Neutralinos = mixtures of the bino, neutral wino, and neutral Higgsinos
Charginos = mixtures of the charged wino and charged Higgsino
The lightest supersymmetric particle is usually expected to be a neutralino.

So this putative discovery may mean that it'll be awfully hard for the LHC to detect supersymmetric particles.

Macroinvertebrate wrote:

Weaver wrote:

THWOTH wrote:

rainbow wrote:
What I want to know is why they couldn't have just studied small hadrons, and saved us all a packet of money.

Small hadrons are harder to find than their larger brethren. They are generally obscured by other material in very rarefied environments and have to be rooted out by the sensitive snouts of specially trained pigs.

And given the environment of super-colliders, we'd need spherical pigs that can survive a vacuum.

Does not compute...

Weaver wrote:

Macroinvertebrate wrote:

Weaver wrote:

THWOTH wrote:
Small hadrons are harder to find than their larger brethren. They are generally obscured by other material in very rarefied environments and have to be rooted out by the sensitive snouts of specially trained pigs.

And given the environment of super-colliders, we'd need spherical pigs that can survive a vacuum.

Does not compute...

http://en.wikipedia.org/wiki/Spherical_cow

twistor59 wrote:Are there any non-MSSM models which are taken seriously and which have sparticles which are in LHC range ? I'd wet myself if a supersymmetric partner were to be discovered!

Weaver wrote:

Macroinvertebrate wrote:

Weaver wrote:

THWOTH wrote:
Small hadrons are harder to find than their larger brethren. They are generally obscured by other material in very rarefied environments and have to be rooted out by the sensitive snouts of specially trained pigs.

And given the environment of super-colliders, we'd need spherical pigs that can survive a vacuum.

Does not compute...

http://en.wikipedia.org/wiki/Spherical_cow

Ihavenofingerprints wrote:I don't fully understand the "3.5 sigma" result they got last year. Does that mean the chance of it being a detection of the higgs is 99%+?

Or does it work some other way? I'm a bit confused as to what the significance is.

CERN ‏ @CERN
First beam of the year circulating in the #LHC just before midnight. Let the 2012 LHC run begin!

New Particle Discovered at CERN

ScienceDaily (Apr. 27, 2012) — Physicists from the University of Zurich have discovered a previously unknown particle composed of three quarks in the Large Hadron Collider (LHC) particle accelerator. A new baryon could thus be detected for the first time at the LHC. The baryon known as Xi_b^* confirms fundamental assumptions of physics regarding the binding of quarks.