Search FQXi

If you have an idea for a blog post or a new forum thread, then please contact us at, with a summary of the topic and its source (e.g., an academic paper, conference talk, external blog post or news item).
Forum Home
Terms of Use

Order posts by:
 chronological order
 most recent first

Posts by the blogger are highlighted in orange; posts by FQXi Members are highlighted in blue.

By using the FQXi Forum, you acknowledge reading and agree to abide by the Terms of Use

 RSS feed | RSS help

Jamahl Peavey: on 1/14/13 at 18:40pm UTC, wrote Interesting

Fred Diether: on 11/22/12 at 20:01pm UTC, wrote Hi Ben, Yep, every year that passes SUSY loses more and more ground. ...

Ben Still: on 11/21/12 at 21:17pm UTC, wrote The LHCb experiment at CERN recently announced results that put the theory...


Steve Dufourny: ":) and jumping :)" in Alternative Models of...

Gary Simpson: "Steve Dufourny wrote: "Dear Zeeya , Could you tell us when the contests..." in Alternative Models of...

Eon: ""I’m localized I can go here, or here, or here, and I can’t be in two..." in The Times They Are...

Georgina Woodward: "To clearly see the 50:50 probability for boxes that are different it would..." in Physics of the Observer -...

Georgina Woodward: "Here is another analogy. In one way I think it is better because it clearly..." in Physics of the Observer -...

custom essay: "We are definitely merging with our technology. The ideas you have suggested..." in Are We Merging With Our...

Frank DiMeglio: "DEFINITIVE PROOF THAT GRAVITY IS ELECTROMAGNETISM Energy has/involves..." in New Podcast: A MICROSCOPE...

Joe Fisher: "Georgina, Nothing does indeed mean nothing, primarily because nothing has..." in In Search of a Quantum...

click titles to read articles

In Search of a Quantum Spacetime
Finding the universe's wavefunction could be the key to understanding the emergence of reality.

Collapsing Physics: Q&A with Catalina Oana Curceanu
Tests of a rival to quantum theory, taking place in the belly of the Gran Sasso d'Italia mountain, could reveal how the fuzzy subatomic realm of possibilities comes into sharp macroscopic focus.

Dropping Schrödinger's Cat Into a Black Hole
Combining gravity with the process that transforms the fuzzy uncertainty of the quantum realm into the definite classical world we see around us could lead to a theory of quantum gravity.

Does Quantum Weirdness Arise When Parallel Classical Worlds Repel?
Quantum mechanics could derive from subtle interactions among unseen neighboring universes

Wrinkles in Spacetime
Searching for defects in the fabric of the cosmos could help physicists home in on the correct theory of quantum gravity.

July 23, 2016

CATEGORY: Blog [back]
TOPIC: Bad News for Supersymmetry? [refresh]
Bookmark and Share
Login or create account to post reply or comment.

Blogger Ben Still wrote on Nov. 21, 2012 @ 21:17 GMT
The LHCb experiment at CERN recently announced results that put the theory of Supersymmetry into ever growing doubt.

Our current picture of the Universe at the smallest scale is wrapped up in the mathematics of the Standard Model of particle physics, with 12 building blocks (6 quarks and 6 leptons), four force carrying particles and the Higgs boson (see image, right). It can be used to predict the ways in which the twelve building blocks of Nature interact through the exchange of the four force carrying particles. Then there is the Higgs boson, which gives mass to all of these particles. It is known that this model isn’t the final word in our understanding of Nature and there are a number of theories which try to answer the questions the Standard Model can’t.

Supersymmetry is the poster boy of these “new physics” theories. In brief it states that every building block and force carrying particle has a supersymmetric partner called a sparticle. These sparticles have not been seen yet because they are believed to have a large mass, so you need large energies to create them because, as Einstein told us, E=mc2. It is hoped that the record-breaking energies of the Large Hadron Collider (LHC) will be enough to create sparticles and confirm that supersymmetry can go from theory to fact.

The LHCb experiment is designed to look for rare decay of heavy particles called B-mesons. B-mesons are pairs of quarks and anti-quarks where at least one is a bottom quark. The latest results are interested in the decay of Bs mesons; an anti-beauty and a strange quark. The result published by the experiment last week talks about the rare decay where a Bs forms a two particles called Muons (μ).

Following the rules of the Standard Model there are a limited number of ways in which a Bs can decay into two Muons; we can draw these as Feynman diagrams (image right). When the numbers are plugged into the maths it is calculated that if we have just the standard model routes available, those in black, then a decay of Bs -> μμ should happen about 3 times for every billion deaths of a Bs. If, however, supersymmetry were to exist then this number would be higher because with sparticles (marked in red/green) around there are more routes to take to get from a Bs to two Muons.

The result published by LHCb shows a high level of agreement with the standard model result of 3 parts per billion. This suggests it is unlikely that there are “new physics” routes to get from a Bs to two. This could be because LHCb have been unlucky and through nothing but pure chance seen fewer Bs -> μμ than it should have; more time and data will be the test of this. Another possible reason for the result is the current 8TeV energy of the LHC machine is not high enough to create sparticles; the good news here is the LHC will be increasing its energy to around 13TeV in 2014. Or it could be that supersymmetry is not the right route to explaining the shortcomings of the Standard Model. Either way supersymmetry still remains a theory and the standard model stands strong but time and energy may yet change all that.


Ben Still is a particle physicist at Queen Mary, University of London, UK.

this post has been edited by the author since its original submission

report post as inappropriate

Fred Diether wrote on Nov. 22, 2012 @ 20:01 GMT
Hi Ben,

Yep, every year that passes SUSY loses more and more ground. IMHO, a nice theory Nature choose not to do. If we take the viewpoint that the quantum "vacuum" is a relativistic medium of fermionic pairs, then all elementary gauge bosons are merely "wavicles" of the medium. So there can't be any kind of supersymmetry between fermions and bosons. For a different perspective see my essay.



report post as inappropriate

Jamahl A. Peavey wrote on Jan. 14, 2013 @ 18:40 GMT

report post as inappropriate

Login or create account to post reply or comment.

Please enter your e-mail address:

And select the letter between 'F' and 'H':

Note: Joining the FQXi mailing list does not give you a login account or constitute membership in the organization.