Saturday, June 04, 2011

Indian SUSY island barely survived ATLAS' visit to 165/pb

On their conference notes page at CERN, the ATLAS Collaboration began to produce many new papers that use the 2011 data. At this moment, the fifth one is
Search for squarks and gluinos using final states with jets and missing transverse momentum with the ATLAS detector in sqrt(s) = 7 TeV proton-proton collisions (PDF)
They studied lepton-free events - dijet, three-jet, four-jet, with possible missing transverse energy - in order to find supersymmetry's gluinos. They didn't find any significant evidence of them which raised the lower bound to 725 GeV for the gluino mass in general and about 1 TeV for gluino mass if it is equal to the squarks' mass.

Miss Gluino, a vampire alchemist, is looking pale in the new paper. She will have to eat some blood, gore, and al-chemical food and become more massive in order to survive.

Clearly, the LHC is starting to penetrate to the territory of the parameter space that was possible according to all the pre-LHC data. As an example, the Indian supersymmetric island I was discussing in December 2011 survived once again, despite its having pretty low masses. But it had to be lucky.

The light stop is at 390 GeV, the light sbottom is at 720 GeV, other squarks are at 800-900 GeV while gluinos are at 934 GeV which is different. As you can see, the conditions of the new ATLAS paper are satisfied. But a single improvement that happens to produce the same negative outcome will eliminate the Indian supersymmetric island, too.

And maybe it will not and something more fascinating will take place.

The required amount of data has actually been accumulated by the LHC collider already, because each of the main two detectors at the LHC has collected over 650/pb at this point, which is 4 times larger than the dataset used in the paper we are discussing now, and the pile of the data is just waiting to be processed by the experimenters.

The latest gluino paper from ATLAS reports three events (two three-jet and one one-jet) that are close to the effective mass of 1.5 TeV but they're not enough to make me excited as much as the 3.34 TeV bump in the dijet spectrum.

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