Quote:
Originally Posted by CraigS
Hi Petra;
Pretty convoluted graphs, eh ?
As I understand it, from the first graph, the intersection of black line and the red line indicates that if there were a Standard Model Higgs, (HB), boson at 140GeV, then the probability of getting a stronger signal than the one seen, would be 0.95.
Also, at the 140GeV point, there is almost a 3 sigma excess. What this means is that if there were not an HB at this point, then the probability of getting a weaker signal than the one observed, would be about 0.99. So, the signal indicating a Higgs boson at 140GeV is five times stronger than the one tending to exclude it.
The bottom plot of the second graph ('Best fit sigma/sigma SM' etc), takes into account past observations, (Bayesian analysis), and theoretical predictions, and assigns a higher probability that the HB will most likely be found at the lighter end of the mass scale. The presently found results are then re-plotted against the 'expected' range, in order to narrow down the mass search region. It shows the region from 110 to about 180 GeV, has the most chance of where theory and past observations would predict/expect finding the notorious HB.
The plot on top of this one has left me for dead .. I haven't got the time today to work out exactly what its saying … (sorry).
Hope that helps.
Cheers
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Petra and Craig,
Even though there is one LHC there are two experiments going on here, the Atlas and CMS searches. Both have the objective of locating the Higgs boson.
For the top plot in the second graph, each test produces it's own sample data. The data from Atlas and CMS has been combined.
While both tests separately should show the Higgs boson having the same mean energy value, sampling data from both experiments may indicate that the mean Higgs boson energy has deviated by some particular amount.
The P-value is the probability that this deviation is due to sampling errors in the tests.
The theoretical values are based on
Monte Carlo experiments.
These are in effect mathematically generated virtual particle accelerator experiments.
Regards
Steven