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Posts Tagged ‘CMS

CMS Sees No Gluinos

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By Tommaso Dorigo

Blogging from the whereabouts of one of the most beautiful places of the Mediterranean, Balos Beach (see picture), I wish to draw your attention today to one fun search that CMS produced on data collected in 2010: the one for gluinos in events with six jets.

Gluinos are particles predicted by supersymmetric models. They are the super-partner of the gluon, the carrier of strong interactions. If they exist, gluinos must be copiously produced in proton-proton collisions, because they carry the colour charge which “couples” them to standard quarks and gluons contained in the proton. In a few models including so-called “R-parity violation”, gluinos will produce three hadronic jets in their decay, and so the final state of gluino pair production may indeed feature six energetic jets.

Six-jet events arise warm memories in this researchers’ mind -I worked at them when the top quark was still at large, and the CDF-Padova group was challenging the enormous QCD background to spot the tiny signal of a all-hadronic decay of the top-quark pairs we hoped the Tevatron collider was producing…… Read the rest of this entry »

Written by physicsgg

July 19, 2011 at 9:39 am

Posted in High Energy Physics

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Elusive Higgs slips from sight again

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Now you see it, now you don’t. Rather like a conjurer’s white rabbit, the elusive Higgs boson may have slipped from sight again.
A recent report hinted at a glimpse of the long-sought particle at a major detector at the Large Hadron Collider (LHC) at CERN near Geneva, Switzerland. But a second detector has now checked its own data and found no corroborating sign of the particle.
The Higgs boson is thought to endow other particles with mass, but has yet to be observed. Four physicists associated with the LHC’s ATLAS detector claimed to have found an anomalous “bump” in its data, possibly due to Higgs particles decaying into pairs of photons. An abstract of their study was leaked online in April.
Bump, what bump?
Now physicists working on the LHC’s other main detector, CMS, have come up empty in an initial search for a similar bump in their data, according to a document shown to New Scientist. So ATLAS’s bump may not be due to Higgs particles, after all, but instead down to something mundane, such as an error in the analysis.
The internal CMS document has not been released to the public, so the result is still preliminary, as was the news of the original ATLAS bump, for that matter, which was leaked before it was reviewed or endorsed by the ATLAS collaboration.
Both leaks are a testament to the excitement surrounding the Higgs. With a result this hot on the horizon, expect more fits and starts in the months to come.
http://www.newscientist.com/article/dn20442-elusive-higgs-slips-from-sight-again.html

Written by physicsgg

May 4, 2011 at 9:27 pm

Posted in High Energy Physics

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