Physicists find hints of a light Higgs boson in LHC data

[n2doc]

During Ars' trip to Fermilab earlier this spring, the staff was excitedly talking about their expectations for the summer. That's when the high-energy physics community has many of their meetings, and the expectation was that all of the major players—DZero and CDF at Fermi, and ATLAS and CMS at the LHC—would process as much data as they could and update the community on the search for things like supersymmetry and the Higgs boson, a particle that helps give all others mass. Right now, the Europhysics Conference on High Energy Physics is happening in Grenoble, France, and the folks from Fermi will not be disappointed. The first results from the LHC have greatly expanded the mass range in which the Higgs won't be found, and left open the possibility that it might eventually turn up in the area of 140GeV.

Results have been presented by people from both ATLAS and CMS. Each of these has looked for evidence of the Higgs in different "channels," with each channel representing a different process for producing a Higgs, which will then decay into a spray of distinct particles and photons. (Symmetry Breaking has a decent explanation of some of this.) Each one of these channels is sensitive to a different range of energies, both because of the process that triggers the event, and because the background of similar-looking events also depends on the energy. As a result, you get a complex set of graphs, each generated in a different channel.



Each of the dotted curves shows the expected number of events based on the background of similar-looking events produced by something other than a Higgs decay. The solid curves are the rates of events registered by (in this case) the ATLAS detector. Merging all of these individual channels together gets you a single curve that spans the whole energy range, shown below.

For the most part, the observed data (again, a solid line) is very close to that predicted by a Standard Model background that doesn't include the Higgs (within the green and yellow bands). This indicates the detector is not seeing anything unusual in these regions. In some areas, like the one around 375GeV, it's seeing so little of the Higgs-like events that the observed data is significantly below that expected from the background. This has allowed them to exclude the possibility that the Higgs is hiding between 294 and 450 GeV. In other areas, like the one centered around 175GeV, the observations were close to what was expected, but we've seen enough of these collisions to know the Higgs can't be there, or the detectors would have seen many more events in the area.


more

http://arstechnica.com/science/news/2011/07/hints-of-a-light-higgs-in-lhc-data.ars

[girl gone mad]

1. Only one region remaining..

but nothing that breaks standard model, according to the ATLAS presentation.

"Interesting excesses possible 120-145 GeV at 2.8 standard deviations." (unconvincing?)

The CMS results seem to match up, but I'm too lazy to analyze the data today and will wait to see what the consensus is from Europhysics 2011.

Another possibility is that the Higgs is in the excluded range of 150-180 GeV, but with a smaller production rate than standard model predicts.

I'm biased since I hope they don't find it, but we are running low on possibilities.

[Sylwester Kornowski]

2. A light Higgs boson

The Everlasting Theory ( http://www.cosmology-particles.pl ) leads to conclusion that the ratio of the coupling constants for the weak interactions of proton and muon is in approximation 20,000. When we multiply this number by the distance of mass between the charged and neutral pions (about 4.6 MeV) we obtain the mass of the Z boson (about 92 GeV). The distance of mass between the neutral and charged kaons (about 4 MeV) leads to the mass of the W bosons (about 80 GeV). The Everlasting Theory shows also that baryons have the atom-like structure - there is the core and outside it is obligatory the Titius-Bode law for the strong interactions. In the d=1 state, there are the relativistic pions - they are under the Schwarzschild surface for the strong interactions so the proton is the stable particle. The distance of mass in the d=1 state between the relativistic charged and neutral pions is 7.1 MeV. This distance of mass leads to particle which mass is about 140 GeV. This particle is associated with the pions (not with the kaons) so it is the Z-boson-type particle. This means that there should be the hadron jets only and it is consistent with experimental data. We can see that the NEW particle leads to the atom-like structure of baryons. Origin of mass is different and is associated with the properties of the Einstein spacetime.

[Bosonic]

3. Some similar results uncovered with Tevatron

A US particle machine has seen possible hints of the Higgs boson, it has emerged, after reports this week of similar glimpses at Europe's Large Hadron Collider (LHC) laboratory.

The Higgs boson sub-atomic particle is a missing cornerstone in the accepted theory of particle physics.

Researchers have been analysing data from the Tevatron machine near Chicago.

The hints seen at the Tevatron are weaker than those reported at the LHC, but occur in the same "search region".

http://www.bbc.co.uk/news/science-environment-14266358