M-theory 2023

In the recent Prometheus trailer (Alien prequel), Peter Weyland in his 2023 TED talk mentions M-theory as one of mankind's great accomplishments.  M-theory isn't yet complete, but I'm pretty certain it (or its completion) will be complete by 2023.  Either way, it's entertaining to imagine the status of high energy physics 11 years from now.

Majorana Fermion detected?

While all eyes are on the LHC to discover new, interesting particles species, condensed matter physicists have been working hard in attempts to detect Majorana fermions and Magnetic Monopoles in solids.  In today's talk at the American Physical Society’s March meeting in Boston, Massachusetts, Leo Kouwenhoven presented findings that Majorana fermions have been detected in an indium antimonide nanowire apparatus.  Indium antimonide nanowires are connected to a circuit with a gold contact at one end and a slice of superconductor at the other, and then exposed to a moderately strong magnetic field. Measurements of the electrical conductance of the nanowires showed a peak at zero voltage that is consistent with the formation of a pair of Majorana particles, one at either end of the region of the nanowire in contact with the superconductor. As a sanity check, the group varied the orientation of the magnetic field and checked that the peak came and went as would be expected for Majorana fermions.

Although other groups have previously reported circumstantial evidence for the appearance of Majorana fermions in solid materials, Jay Sau, a physicist at Harvard University in Cambridge, Massachusetts, who attended Kouwenhoven’s talk, says that this is a direct measurement. “I think this is the most promising-looking experiment yet,” he says. “It would be hard to argue that it’s not Majorana fermions.”

Multiple schemes have been proposed in which Majorana fermions act as the 'bits' in quantum computers, although Sau cautions that it’s not yet clear whether those created by Kouwenhoven will be long-lived enough to be used in that way. 

- Read more at Nature

The 5% Standard Model

As the LHC's Higgs hunt continues, it's worthwhile to reflect on the current state of cutting-edge experimental particle physics, as a whole.  Indeed the Higgs boson is a prediction of the Standard Model of particle physics, but as former CERN theoretical physicist John Ellis admitted, in the range 114-135 GeV the "present electroweak vacuum would be unstable for such a light Higgs in the Standard Model" forcing one to come up with new physics to stabilize it.  By "new", this means physics beyond the Standard Model, such as for example, supersymmetry.  Yet, let's pretend the Standard Model is nice and stable with a ~125 GeV Higgs particle.  Does it tell us about every type of matter in the universe?  Sadly, it doesn't.  Ordinary matter accounts for only 4.6% of the mass-energy content of the observable universe, while mysterious dark matter makes up about 23%.  The rest of the mass-energy content, about 72.4%, is in the form of dark energy.  So cosmologically, the Standard Model doesn't seem so standard after all. 

So what kind of model explains the physics of dark energy and dark matter (the 95.4% of the universe), along with the 4.6% nicely described by the Standard Model?  Many theorists would agree such a model must come from a complete theory of quantum gravity.  The leading contender for such a theory is M-theory, the theory underlying the 10-dimensional string theories and 11-dimensional supergravity.  There also exist other theories, such as Loop Quantum Gravity, which essentially aims to "quantize" space via Wilson loop operators.  Ultimately, the goal is unification of all forces and matter in the universe, using just a single theory.  And this theory, in turn, should describe 100% of the universe.

Are we close to figuring out a complete theory of quantum gravity, hence a theory of all matter and forces?  There are hints that we are, but as always, many hurdles are mathematical.  Historically, Newton had to invent Calculus to describe motion properly.  Einstein had to invoke the tools of Riemann's Differential Geometry to describe space-time curvature.  And will it now be Connes' Noncommutative Geometry that will serve as the magic bullet for quantum gravity?  There is evidence that it might, as the coordinates of branes in string/M-theory are naturally noncommutative.  Erik Verlinde has even proposed a model for dark energy and dark matter, which as a matrix model, is an application of noncommutative geometry.  From a historical perspective, the use of new geometrical mathematics has proven fruitful, so we may very well be on the verge of a new physics revolution.

Unofficial Higgs combined plots are in

As promised, Philip Gibbs has produced combined plots for the Higgs mass, which includes data from LHC, Tevatron and LEP. Notice that nice peak centered at 124-125 GeV!

If this is a light E6 GUT Higgs, we'd expect to see a light isosinglet quark such as the D quark at the LHC very soon. We should even be able to predict its mass (~>250 GeV). A Z' boson would also be nice. For more info, see slides here and here. On to 2012!

Higgs rumors were correct

The official results are in, at least for the LHC's 2011 data, and it appears the rumors were quite accurate. See TRF and QDS for further details. To quote CMS member Dorigo, who stated there is now "Firm Evidence" with the current data,

So the summary is that ATLAS has a 3.6-sigma significance at 126 GeV, by combining their three most sensitive channels; CMS has a 2.4-sigma significance at 124 GeV, by combining all the meaningful search channels -even less sensitive ones.

After an ATLAS and CMS combined plot is produced, there might very well be over 4 sigma evidence for a light Higgs. I'm certain Philip Gibbs is working on a combined plot at this very moment. There is still a Christmas present to be delivered! Stay tuned.

Why a light Higgs is cool

As to why many theorists are excited over news of a possible light Higgs boson with 125 GeV mass, here's a memorable excerpt from a September 2011 interview with Clerk Maxwell Professor of Theoretical Physics and former CERN staff member John Ellis:

In the first scenario (114-135 GeV), we could be looking at a Standard Model Higgs boson. This range has been refined experimentally: recent LHC results presented in Mumbai excluded the Standard Model Higgs from about 135 GeV to about 500 GeV, while LEP had previously excluded it up to 114GeV. That leaves a narrow low-mass range of about 20 GeV where it could lie. But if found in this range, the Standard Model theory would still be incomplete; the present electroweak vacuum would be unstable for such a light Higgs in the Standard Model, so we would have to come up with new physics to stabilise it.

Higgs Candidate Events

While there has been no official announcement on the possible Higgs mass from CERN, there are some nice images available on possible candidate events where the Higgs might have appeared, as mentioned at TRF.

Candidate events in the CMS Standard Model Higgs Search using 2010 and 2011 data (Click images to enlarge)

A typical candidate event including two high-energy photons whose energy (depicted by red towers) is measured in the CMS electromagnetic calorimeter. The yellow lines are the measured tracks of other particles produced in the collision.

A typical candidate event including two high-energy photons whose energy (depicted by red towers) is measured in the CMS electromagnetic calorimeter. The yellow lines are the measured tracks of other particles produced in the collision. The pale blue volume shows the CMS crystal calorimeter barrel.

Real CMS proton-proton collision events in which 4 high energy electrons (green lines and red towers) are observed. The event shows characteristics expected from the decay of a Higgs boson but is also consistent with background Standard Model physics processes.

Real CMS proton-proton collision events in which 4 high energy electrons (green lines and red towers) are observed. The event shows characteristics expected from the decay of a Higgs boson but is also consistent with background Standard Model physics processes.

Real CMS proton-proton collision events in which 4 high energy muons (red lines) are observed. The event shows characteristics expected from the decay of a Higgs boson but is also consistent with background Standard Model physics processes.

All images and descriptions copyrighted property of © 2011 CERN and used for educational purposes.

Higgs rumors at 124.6 GeV

December 13 comes ever closer and the rumors about the Higgs mass get more detailed. Lubos Motl has commented on a recent post at QDS by Tommaso Dorigo in which he seems to hint at a possible Higgs mass from diphoton Higgs decay channels

- gamma: a gamma-ray is a photon, i.e. a quantum of light. A very energetic one, to be sure: a gamma ray is such only if it carries significantly more energy than a x-ray, so above a Mega-electron-Volt or so. The gammas we will be hearing about are those directly coming from a Higgs boson decay, and these have an energy of 62.3 GeV, equivalent to the kinetic energy of a mosquito traveling at 9 centimeters per second.

Here, the Higgs mass 124.6 GeV = 62.3 GeV x 2, from a process that can be written as H -> gamma gamma - where the Higgs decays to two high energy photons. Of course, Tommaso admits

I teased my most gullible readers with a (wrong) covert give-away of the Higgs mass ...

Either way, it is fun to speculate when the actual announcement is only a few days away. So let's see how close this 124.6 GeV is to the official (statistical) CMS value on Monday.

Higgs rumors at 125 GeV

As we all await CERN's official CMS and ATLAS results for the 2011 Higgs hunt, rumors about its mass have surfaced at notable blogs such as Philip Gibbs' viXra log, Peter Woit's Not Even Wrong and Tommaso Dorigo's Quantum Diaries Survivor. As mentioned by "Alex" in the viXra comment section,

Today rumour is: Higgs at 125 Gev around 2-3 sigma…

Such a rumor, if true, would not only indicate evidence for the existence of the Higgs boson, but is evidence for a light Higgs boson (115-135 GeV), which popular models such as E6 GUTs and M-theory on G2-manifolds predict. Of course, 2-3 sigma evidence isn't really conclusive but it does favor physics beyond the Standard Model. These are exciting times and by December 12 and 13 we'll all get to see if the rumors are true. Moreover, Philip Gibbs has also promised everyone a combined CMS and ATLAS plot once the data is released. How's that for an early Christmas present?

Update: Over at Lubos Motl's TRF blog, a commenter "azerty13" said he received the following email from CERN Director General Rolf Heuer:

Dear colleagues,

I would like to invite you to a seminar in the main auditorium on 13 December at 14:00, at which the ATLAS and CMS experiments will present the status of their searches for the Standard Model Higgs boson. These results will be based on the analysis of considerably more data than those presented at the Summer conferences, sufficient to make significant progress in the search for the Higgs boson, but not enough to make any conclusive statement on the existence or non-existence of the Higgs. The seminar will also be webcast.

Rolf Heuer

Such an email, if genuine, definitely supports the 2-3 sigma portion of the 125 GeV Higgs mass rumor. Stay tuned.

Update: As mentioned at viXra log, the latest incarnation of the rumor at Woit's blog gives 3.5 sigma in ATLAS and 2.5 sigma in CMS which amounts to about 4.3 sigma combined for the 10/fb. Keep in mind 5 sigma evidence is what is required at this stage of the Higgs hunting game.