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How Hard Will The Hunt Be? August 6, 2008

Posted by gordonwatts in D0, Fermilab, Higgs, physics.

Yesterday I mentioned that the Tevatron experiments had finally started to rule out the Higgs. I thought I’d post another plot that shows exactly how hard it will be – and so gives you an idea of how much hope the Tevatron has of actually catching the Higgs. Click on the plot to get an enlarged version of the jpeg (here for details).

The most important lines in that plot are the black one (1-CLs Observed) and and the 95% CL thick blue line. The thick blue line is the point at which, in our best statistical estimate, we are 95% confident that we have not observed anything. While the blue line is the “goal”, the black line is where we are now – the current observation. A lot goes into that black line – many different physics analysis contribute (from both D0 and CDF), the physics of the Higgs decay, the physics of how the Higgs boson is supposedly made, and how good our detector is at seeing the Higgs. As you can see, we have just peaked above the 95% level near 170. And that is what allows us to say that we’ve excluded the Higgs around 170 GeV.

Now, the future. You’ll note that the curve is pretty flat near where it peaks above 170. That says to me that when we add more data and minor analysis improvements we will be able to quickly broaden the amount of the observed line is above the 95% CL line. Where the black line is steeply falling, however, it require a huge amount of work (even if it is possible at the Tevatron).

Finally, in yesterday’s post the plot started at 114 GeV. This one starts at 155. What about everything from 114 to 155? Yes — we are working on that. For example, at D0 we have individual results already (and if you look at this plot, given the discussion, you can see that how we are doing as far as getting towards ruling things out at low mass – though the plot is a very different type of plot – but you can guess what is going on if you are not familiar with it). I couldn’t find the recent update of the CDF combined results. But the low mass combination between the experiments was not completed in time for ICHEP. I’m hopeful that we will see it soon – but as they say, it ain’t out until it is ready to be out!



1. Joe - August 8, 2008

You being a Rochester PhD, I think you should refer to the Mass Boson as the Higgs-Brout-Englert-Guralnik-Hagen-Kibble Particle.

Just a mere suggestion.

2. gordonwatts - August 10, 2008

Joe, you are correct, of course.

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