Higgs particle heavier than ever?


Today in Mumbai (India), at the Lepton-Photon 2011 Conference, talks announcing new results from LHC were held. Data taking claimed almost doubling of data since July Conference in Grenoble. The results were striking and somewhat unexpected. In order to have an idea you should read this CERN press release and the general mood of people at CERN on the Guardian. What happened can be summarized in a few words: all the signals in the expected mass range for the Higgs particle just weakened and, as clearly pointed out by Tommaso Dorigo in his blog (see here), the possible signal at around 140 GeV should be dead and buried already. What remains after these announcements is a signal at around 120 GeV that also has lose its grip lowering confidence. For your considerations I would like to show you the main graphs from ATLAS and CMS

Aleandro Nisati, an Italian researcher at INFN and ATLAS Physics Coordinator, is claiming that no signal above 2.1 sigma is seen in the mass range between 110-600 GeV, in his talk. The remain at around 120 GeV is expected to be clarified in the next months with increasing data. My view is that this is already borderline with respect to Standard Model expectations and could prove to be a fluke as well. So, what could one conclude from a scenario like this? Perspectives are open to a lot of new exciting physics. It is important to stress that these results do not exclude at all the existence of Higgs particle but they seem to make its mass even more heavier. This scenario agrees quite well with a view of a strongly coupled Higgs boson as I have already pointed out in several posts and the most recent one. This in turn will entail a proof of existence for supersymmetry (see here).

I think that this situation is the most exciting one for a lot of reasons. We, the theoreticians, should start to take our pencil and paper again and turn back at study while people at CERN keep on performing their excellent work enlightening us.

Marco Frasca (2010). Mass generation and supersymmetry arXiv arXiv: 1007.5275v2


2 Responses to Higgs particle heavier than ever?

  1. A curious layperson says:

    A (very) naive question from a layperson:

    It seems conceptually understandable that a “light” (100+ GeV) Higgs that is weakly coupled, could impart only a small mass to the light particles, such as the electron. (The weak coupling being the key conceptually understandable part.)

    Could you help explain how a strongly-coupled heavy Higgs can still only impart a small mass to the electron, etc.? Is it that the Higgs is only strongly coupled to itself, yet weakly coupled to the light particles?

    Thanks for helping to clarify, and for your excellent blog.

    • mfrasca says:

      Dear curious layperson,

      It is not at all understandable that a light Higgs particle should give small couplings. Standard Model is tuned in such a way to have Yukawa couplings, different for each particle, in such a way that a single value of the vacuum expectation value of the Higgs field will give the right mass for each particle. Then, we assume that these Yukawa couplings are small enough to permit you to do perturbation theory and compute cross sections and all that. This scenario is consistent, given the physical masses of the particles, and works quite well from a theoretical standpoint. This is also the reason why a lot of effort is involved currently worldwide in places like CERN to validate it. So, by itself, the mass of the Higgs boson is not involved here but just the vacuum expectation value of the Higgs field.

      Where does mass enter? In the version of the Higgs mechanism used in the Standard Model one has to assume that the mass of the Higgs particle is not so large and its self-interaction small otherwise weak perturbation theory breaks down for the Higgs field and we are no more able to manage it. Besides, this field entails a possible Landau ghost making nonsensical to consider it for such large couplings. This is the reason why people consider such a situation unphysical.

      All this is pointless if you have a way to do quantum field theory for a strongly coupled field. This is a line of research pursued since 1980 by Carl Bender and other fine researchers as Guralnik himself, one of the founders of the Higgs mechanism as we know. This idea is today mature enough to do an innovative proposal as shown in my paper. The most important conclusion to be drawn from this is that, in a strongly coupled Higgs field, mass are generated dynamically, a la Schwinger, and supersymmetry is needed.


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