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Selfsim
2012-Jul-05, 07:18 AM
So, amongst all the excitement about the detection of the new 'HB-like' particle at 125 to 126 GeV, has anyone noticed the correlation with a String Theory prediction which was released in this paper (published 30th April, 2012 in APS Physcial Review D) ?

Higgs mass prediction for realistic string/M theory vacua (http://arxiv.org/pdf/1112.1059v1.pdf):

Recently it has been recognized that in compactied string/M theories that satisfy cosmological constraints, it is possible to derive some robust and generic predictions for particle physics and cosmology with very mild assumptions. When the matter and gauge content below the compactication scale is that of the MSSM, it is possible to make precise predictions. In this case, we predict that there will be a single Standard Model-like Higgs boson with a calculable mass 105 GeV <~ Mh<~129 GeV depending on tan beta (the ratio of the Higgs vevs in the MSSM). For tan beta > 7, the prediction is : 122 GeV<~ Mh<~129 GeV.
(Not sure if the annotation came out particularly well in the above quote ... see the abstract of the paper for clearer annotations).

From the conclusion section:

If the prediction for the Higgs mass turns out to be correct, it would be an extremely important step forward in relating the string/M theory framework to the real world and would open up many opportunities for learning about the string vacuum we live in. In addition to learning about tan beta and as described earlier, it could tell us that the gauge and matter content of Nature is indeed that of the MSSM!
If not, this would imply that one or more of the attractive assumptions in the paper have to be relaxed.
Interesting that String Theory may have predicted what may now have been detected as the HB at the LHC !

The big question would seem to be:
'Was the String Theory prediction accurate enough to be confirmed as String Theory's first legitimate prediction ?'

Comments welcome.

Regards
PS: Apologies, in advance, if this has already been noted in other posts about the detection announcements. (I did check, but I may have missed it).

Jens
2012-Jul-05, 07:34 AM
Not totally sure, but wasn't the 125 GeV bump already being talked about last year? IIRC there was another announcement from CERN, maybe late last year, where they said they had eliminated almost all the other areas, and were seeing a signal at that place. So it was pretty clear at that point that the Higgs wouldn't be found anywhere else. So was that really a prediction made before the signal was starting to show up?

Ivan Viehoff
2012-Jul-05, 08:37 AM
Whatever the mass or properties the Higgs Boson turned out to have, some string theorists would have touted it as a triumph for the predictions of string theory, as pointed out here.

http://www.math.columbia.edu/~woit/wordpress/?p=4262

Selfsim
2012-Jul-05, 09:03 AM
Not totally sure, but wasn't the 125 GeV bump already being talked about last year? IIRC there was another announcement from CERN, maybe late last year, where they said they had eliminated almost all the other areas, and were seeing a signal at that place. So it was pretty clear at that point that the Higgs wouldn't be found anywhere else. So was that really a prediction made before the signal was starting to show up?Hmm ....
So, on Dec 8th 2011, a blog entry in Scientific American (http://blogs.scientificamerican.com/degrees-of-freedom/2011/12/08/lhc-physicist-joe-lykken-on-higgs/) which contained an interview by David Castelvecchi with Joseph Lykken (Fermilab Theoretical Physicist) appeared. The following part is relevant:


Gordon Kane and his collaborators posted a paper on the arXiv this week that claims to predict that the mass of the Higgs is 125 GeV based on string theory. [Kane says he has presented the results at an international conference in August, so his team's calculation was not made now to match the Higgs mass that's being rumored.] If the rumors pan out and the Higgs’s mass does turn out to have that value, would you call this a success of string theory?I would say it would be an example of a successful connection between string theory and experiment. The trouble is, for all we know, there might be 10,000 other ways of starting with string theory and getting the same Higgs mass, and [all those versions of string theory] may differ in other respects. This is just a problem of string theory having too many solutions. But having any successful solution that gets you from string theory to a real measurement–that’s a big step forward.

So, it would seem that the Kane et al paper, made the prediction in August, but the CERN announcements weren't released until December 13. Even the preliminary 'evidence' releases weren't available until November, IIRC.

Sounds like a prediction to me !

Cheers

Selfsim
2012-Jul-05, 09:47 AM
Whatever the mass or properties the Higgs Boson turned out to have, some string theorists would have touted it as a triumph for the predictions of string theory, as pointed out here.

http://www.math.columbia.edu/~woit/wordpress/?p=4262Hi Ivan !
Not just 'some string theorists' .. that Woit link is exactly about Kane and this particular string theory based prediction. (Thanks for the link).

Actually, the method Kane uses, (as outlined in his paper), is very much along similar lines to the way QED comes up with the accurate value for the coupling constant for say an electron in an external field, but in order to do this, they still needed to have a hyper-accurate measurement for the absolute value of the electron magnetic moment.

So, perhaps an accurate mass measurement for the HB is the point needed to be obtained, in order to be able to know which String Theory solution is heading in the right direction ? Once they can constrain certain parts, perhaps predictions about other things like gluons, gluino pair production, branching ratios, etc start to become possible (??)

Regards

Jens
2012-Jul-05, 03:00 PM
Sounds like a prediction to me !


Yes, it does sound like a prediction. The only worrying factor is the last paragraph in the quotation, about the possibility that there are 10,000 other ways. Unfortunately, I don't know enough to make any judgment about this.

Ivan Viehoff
2012-Jul-05, 04:05 PM
Yes, it does sound like a prediction.
The reference I gave to the Woit website only presents his latest post in the "This week's hype" category. You need to follow his "This week's hype" posts to get a flavour of the ex post-ness of the "string theory predicted it" hyping up. People have been talking aobut "around 125GeV" as a favoured spot since before the LHC was switched on, and knowing it would be one of the most difficult energy ranges to probe.

It is actually the reverse of a prediction, it is an exclusion. The discovery of the Higgs at 125GeV has excluded those string theories which are inconsistent with that. Someone has found a string "theory" that isn't excluded by this, while acknowledging that there are many more. Well that's something, but I bet they can't actually make it into a complete theory capable of predicting anything outside the SM.