Rare trio of particles observed for first time at CERN's ATLAS Experiment

The ATLAS Experiment observed a rare trio of particles.

Check the video:

Schematic diagram of the decay chain explored in this analysis.

The CMS experiment has submitted a paper for publication describing the firstobservation of a new, excited beauty baryon known as the Ξ^*_b⁰, with a statistical significance of more than 5 standard deviations (5σ) above the expected background. The mass is measured to be 5945.0 ± 2.8 MeV.

in PhysOrg 

Observation of an excited Xi(b) baryon

CMS Collaboration

(Submitted on 26 Apr 2012)

The observation of an excited b baryon via its strong decay into Xi(b)^- pi^+ (plus charge conjugates) is reported. The measurement uses a data sample of pp collisions at sqrt(s) = 7 TeV collected by the CMS experiment at the LHC, corresponding to an integrated luminosity of 5.3 inverse femtobarns. The known Xi(b)^- baryon is reconstructed via the decay chain Xi(b)^- to J/psi Xi^- to mu^+ mu^- Lambda^0 pi^-, with Lambda^0 to p pi^-. A peak is observed in the distribution of the difference between the mass of the Xi(b)^- pi^+ system and the sum of the masses of the Xi(b)^- and pi^+, with a significance exceeding five standard deviations. The mass difference of the peak is 14.84 +/- 0.74 (stat.) +/- 0.28 (syst.) MeV. The new state most likely corresponds to the Xi(b)^{*0} baryon, the J^P=3/2^+ excitation of the Xi(b)^0.

in arXiv
read more in CERN and Quantum Diaries

New data said to narrow search for Higgs particle (updated)

An image released by CERN of a candidate event in the search for the Higgs boson. Credit: CERN

Here are the latest news:

New data said to narrow search for Higgs particle (PhysOrg)

"A scientist from one of two research teams says new data uncovered narrow the regions where an elusive sub-atomic particle believed to be a basic building block of the universe is likely to be found." (PhysOrg.com)

Higgs boson: LHC scientists to release best evidence (BBC)

Scientists find signs of Higgs boson, but stop short of claiming discovery (National Post)

"Scientists at the CERN physics research centre said on Tuesday they had found signs of — although not yet conclusively discovered — the Higgs boson, an elementary particle which is the missing link in the Standard Model of physics.

Fabiola Gianotti, the scientist in charge of the ATLAS experiment at the Large Hadron Collider near Geneva, said the signal was centred at around 126 GeV (Giga electron volts)." (news.NationalPost.com)

Event record: http://cdsweb.cern.ch/record/1406073


CERN Communication: http://press.web.cern.ch/press/pressreleases/Releases2011/PR25.11E.html

"Higgs bosons, if they exist, are very short lived and can decay in many different ways. Discovery relies on observing the particles they decay into rather than the Higgs itself. Both ATLAS and CMS have analysed several decay channels, and the experiments see small excesses in the low mass region that has not yet been excluded.

Taken individually, none of these excesses is any more statistically significant than rolling a die and coming up with two sixes in a row. What is interesting is that there are multiple independent measurements pointing to the region of 124 to 126 GeV. It's far too early to say whether ATLAS and CMS have discovered the Higgs boson, but these updated results are generating a lot of interest in the particle physics community." (CERN)

Mass effect: maybe Higgs, maybe not (Discover Magazine)

"Today, scientists at CERN in Geneva announced their results for their search for the Higgs boson, a subatomic particle that, if it exists, is thought to be responsible for giving other particles mass. It’s no exaggeration to call it a keystone in quantum mechanics, and finding it for sure will be a huge accomplishment for particle physicists.So, did they find it?Maybe. Then again, maybe not." (DicoverMagazine.com)