LHC releases first Higgs search results

LHC(Large Hedron Collider) releases first Higgs search results

The Higgs boson, the elusive particle thought to give all others mass, is the most hyped of all the discoveries that the Large Hadron Collider (LHC) is expected to make. Now the Compact Muon Solenoid (CMS) experiment at the LHC has cast its first glance on this prize.


Excitement must be tempered. The LHC, at CERN near Geneva, Switzerland, can't yet compete with the Tevatron at Fermilab in Batavia, Illinois, in hunting for the Higgs as predicted by the standard model, particle physics's most successful framework.

But, as revealed in a paper posted to the online Physics Arxiv on Saturday, the LHC is already closing in on the version of the Higgs that appears in an alternative, more exotic framework.



For the first time, the Tevatron - formerly the world's most powerful particle smasher and the last experiment to narrow down the possible masses that the Higgs might have - can hear a second set of footsteps on its main stomping ground.

The Tevatron experiments have acquired more than 10 inverse femtobarns of data over the collider's 27 year lifetime - nearly 28 times the amount of data collected by the LHC experiments so far.

With this data, it has been steadily closing the window of possible standard model Higgs masses, ruling out those between 158 and 175 giga electronvolts (GeV). Combined with the previous limit from the Large Electron Positron collider, the elusive boson is thought to hide between 114 and 158 GeV - if it fits into the standard model.


In the recent paper, CMS has considered the Higgs boson in a more exotic framework in which the six known quarks are extended to eight and the three known electron-like particles to four.
The researchers find that if our universe is harboring this "extra generation" of matter, the Higgs is unlikely to have a mass between 144 and 207 GeV. Coupled with the Tevatron's exclusion of the range of 131 to 204 GeV, this slightly narrows the possible mass range for the Higgs within this exotic framework.


The LHC is still in the stage of gathering data and proving the reliability of its experiments, but if the new accelerator keeps the pace it set in 2010, it could seize the Higgs baton from the Tevatron, even for standard model Higgs searches, this summer

Source : http://www.newscientist.com/blogs/shortsharpscience/2011/03/lhc-releases-first-higgs-searc.html
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The three Large Hadron Collider (LHC) experiments that study lead ion collisions all presented their latest results today at the annual Quark Matter conference, held this year in Annecy, France. The results are based on analysis of data collected during the last two weeks of the 2010 LHC run, when the LHC switched from protons to lead-ions. All experiments report highly subtle measurements, bringing heavy-ion physics into a new era of high precision studies.


In its infancy, just microseconds after the Big Bang, the universe consisted of a plasma of quarks and gluons (QGP), the fundamental building blocks of matter. By colliding heavy ions, physicists can turn back time and recreate the conditions that existed back then, allowing us to understand the evolution of the early universe.


Results from the ALICE experiment have provided evidence that the matter created in lead ion collisions is the densest ever observed, over 100000 times hotter than the interior of the sun and denser than neutron stars. These conditions allow the properties of the plasma to be studied with unprecedented detail. ALICE has confirmed the RHIC experiments' finding that QGP behaves almost like an ideal fluid with minimal viscosity. ALICE's presentation also discussed the behaviour of energetic particles in the QGP medium


Source : http://www.physorg.com/news/2011-05-large-hadron-collider-results-quark.html