Thursday, 1 April 2010

April Fools'10: Supersymmetry Discovered at the LHC?!

The floor has hardly been swept after celebrations of the first LHC 7 TeV collisions, and it seems that very soon champagne corks will pop again. That could well be rivers of champagne. I've just been informed that a couple of events captured during the first day of high-energy running contain unmistakable signatures of a particle predicted by supersymmetric theories!!!

The first of these events, reproduced on the right, has been observed in the ATLAS detector. An analysis of the event uncovered that the track marked in red corresponds a charged particle with the mass of approximately 800 GeV!!! This is a new, previously unknown particle, that can only be produced in very high energy collisions such as the ones now available at the LHC.

Let me quote the anonymous ATLAS member who sent me this event display
This is absolutely amazing, it's the greatest day in the history of particle physics.
We thought that reaching discoveries would be a long and painful process, but Nature has been extremely kind to us.

Indeed.

The other striking event comes from the CMS detector. Ironically, it has already been shown at the public presentation on March 30. At that time, however, the particle marked in red has been mistaken for an ordinary muon due to a glitch in the detector electronics that lead to an incorrect measurement of the particle momentum. But a reanalysis of the event lead to a conclusion that this is an 800 GeV particle, definitely not a muon!!! Most likely this particle is of the same kind as the one seen by ATLAS, which means we have an independent confirmation of the discovery.

The most plausible theoretical interpretation is that ATLAS and CMS have observed a chargino: a supersymmetric partner of the standard model W and Higgs bosons. A very interesting conclusion that can be drawn from these two events is that the chargino is quasi stable: rather than decaying immediately, it lives long enough to traverse the entire detector. Such long-lived charginos are predicted by a version supersymmetric theories known as gauge mediation. In that scenario, the chargino decays to a W boson and a gravitino (the supersymmetric partner of the graviton) who is the lightest supersymmetric particle. The decay proceeds very slowly because the gravitino, much as the graviton, has a tiny coupling to ordinary matter.

A few points are still unclear from the theoretical point of view. For example, we would expect supersymmetric particles to be produced in pairs, whereas both experiments observed a single chargino. It is possible that the other chargino might have been lost in a crack of the detector, or charginos are produced together with a different supersymmetric particle species that decays immediately. This conundrum should be resolved as soon as a larger event sample is acquired.

The ATLAS and CMS collaborations are currently embroiled in a fierce battle over the priority of the discovery. This is quite a delicate matter, since the CMS was the first to register a chargino, while ATLAS was the first to correctly interpret it. I believe CERN is refraining from an official announcement of the discovery until the dispute is settled. But we should expect the confirmation anytime soon... stay tuned!

Update:
This post is an April Fools' joke. This was obvious to everyone, of course, because there is no supersymmetry in Nature :-) The displayed events feature ordinary muons; these and more are available at ATLAS and CMS public pages.

39 comments:

Anonymous said...

wow! amazing

Anonymous said...

congratulations to the lhc

Anonymous said...

OMMMGGGGGGGGGGGGG!!!

(Obvious April Fool's is obvious.)

Anonymous said...

"the chargino decays to a photon and a gravitino"

Silly Jester! You didn't even conserve charge. The chargino should decay to a W and gravitino, of course. The rest of your post, though, is an impressive work of honest journalism ;-)

-- M.R.

Anonymous said...

it's still march 31st here...

Hypothalamus said...

Funny how major discoveries are made on 1st of April

Jas said...

Is it true. Its hard to grasp.

Anonymous said...

Gorram it, you got me.

At first I was thinking how ironic it was that this particle was discovered on April Fool's and how hard it would be to convince my friends that it's real, then it hit me.

I tracked down your original image; it's a muon for anyone wondering.

Anonymous said...

wow jester this is incredible!
so much good physics so early on! this is doubly amazing as I also hear there is going to be a joint announcement by cdms and xenon-100later today, apparently dark matter has been definitively discovered and is a technicoloured wimpzillino with a mass of around 795 +- 10 GeV - do you think this is the same particle the LHC has discovered?

Anonymous said...

Funny! Had me going for a full 150 seconds.

reperio said...

muon candidate :)

Jolyon said...

Yeah, yeah, April Fools... Nice post ;-)

reperio said...

This is very serious - it it a joke or what? :) Other blogs are quite so far.

Anonymous said...

April 1?

Marcos said...

HOW GREAT!!!! Today, April 1st, would be remembered as a great date in the history of physics!! ;)

Lumo said...

It's just a fool's joke: the real SUSY mass wasn't 800 but 790 GeV and it wasn't discovered at 14:12 but at 14:16! ;-)

Anonymous said...

Well played, blog author... well played....

Anonymous said...

First April

Anonymous said...

a great day in physics!

Anonymous said...

nice poisson d'avril :-)

Anonymous said...

They were produced in pairs! One pair, split into different detectors at different times. They have discovered non-locality and supersymmetry all at once. I believe this is a prediction of noncritical Liouville flipped SU5 string model.

Somdatta Bhattacharya said...

Couldn't this particle just be a 4th generation charged lepton? The conundrum of the missing chargino wouldn't be there, however whether it would be as long-lived as the muon is something I don't know.

Jérôme said...

Supersymmetry discovered on the 1st of april...I don't know if God is playing dice, but he is surely joking today! ;)

Anonymous said...

Fools day???

Somdatta Bhattacharya said...

If this was an April-fool's day joke it was a good one.

Anonymous said...

nice one ;)

Bee said...

They found something else when they swept the floor after the celebration!

Anonymous said...

the priority issue is a bit more complicated in view of the three candidate mu -> e gamma events observed by MEG at PSI, which can be interpreted as a low energy manifestation of the chargino loop diagram.

Anonymous said...

could it be a stau?

Anonymous said...

This is a real good April 1st hoax :)

Anonymous said...

haha nice one nearly fooled me :D

my flavorized theory which i just conceived five minutes ago also predicts the discovery of bananino and roquefortino particles :)

tulpoeid said...

Jester blogs at a frequency of more than one per month. It has to be April fools' day.

Quantum Shinobi said...

Haha, if only. Happy April 1st! :D

jr said...

It is the long lost Fred particle.

Bewildered said...

I hear they also found dinosaur particles ;). http://user.web.cern.ch/user/news/2010/100401.html

Anonymous said...

Considering the date of discovery, I would think it's a particle of supersplit susy. Or, wait, ...

Pawl said...

Remember the key quantity is the s-parity, that is, the parity of the number of supersymmetry discoveries and retractions taken together. So far the Atlas and CMS experiments taken together still leave us with even s-parity.

Jester said...

Matt, late at April Fools night charge conservation can be waived :-)

Alfredo said...

Nice! I was very surprised and never recalled April Fools' day. We also have a similar day in México, but it is December 28!!!! Nice job!