New combined Higgs limits from CDF: <1.9xSM! August 16, 2007Posted by dorigo in news, physics, science.
A combination of all but one of the CDF analyses looking for a Standard Model Higgs boson has been produced by my colleagues in time for the Lepton-Photon 2007 conference. Mark Neubauer showed it at a Wine and Cheese seminar at Fermilab a week ago. Here is the “money plot”:
In the plot the x axis is the unknown Higgs boson mass, and on the y axis there is a multiplicative factor to apply to the Standard Model predicted cross section for Higgs boson production. The black line is the combined limit, the yellow band the limit one should have expected to place with the applied techniques and data, and the various colored lines show individual limits set with different decay channels.
As you see, CDF improved their limits quite sizably from last summer. With analyzed datasets of 1 to 2 inverse femtobarns, the excluded region is now at less than twice the Standard Model predicted rate, if the Higgs mass is 160 GeV. The limit at lower masses has also been improved quite sizably, but it is still wanting. Note that the result of the search for ZH decays to two b-jets and two neutrinos has not been included in the combination yet. That channel is not the most sensitive, but everything helps…
D0 also has combined its results, and a Tevatron combination is in the making, as far as I know. I am sure no mass region will be excluded this summer, but the game is getting less and less academic. Chances are that next summer we will see the first chipping off of mass values… Unless the Higgs is right there, of course!
I will have more to tell about each of the ingredients to this combination next week…