Of Particular Significance

Why 10 Years To Be Sure There’s No Higgs Particle(s)?

POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON 12/04/2011

After yesterday’s post concerning the media reporting on the Higgs search, a lot of people have been asking me this:  “Given that the Standard Model Higgs particle (the simplest possible Higgs particle) will be found or ruled out in the coming few months, why will it take as long as ten years to be sure nature sports no Higgs particle or particles of any type?”  Well, this deserves a long explanation, which I promise to provide soon, but for starters I recommend my September article on Implications of Current Higgs Searches, which will give you an idea of just how complicated the situation could be.  If it’s too long for you, just look at the figure at the end of the article!  It doesn’t capture the full story, but it may give you a sense for why CERN’s presentations on December 13th cannot possibly mean the end of the Higgs discussion.

Another thing I could recommend, especially to those who are willing to sit through a certain amount of technical mumbo-jumbo enclosed within a largely non-technical discussion, is the first 8 (or even 20.5) minutes of a lecture I gave in 2010 to graduate students who were not Large Hadron Collider [LHC] experts.  (If it loads too slowly you can download it from this page; it is my June 18th lecture.) Even a layperson with some prior knowledge of the LHC and the Higgs particle should be able to get a sense for the main point: how easily nature, with the tiniest twist on the Standard Model Higgs particle, could make the search for the Higgs particle(s) much more difficult and require much more LHC data than we currently have.  This is not to say that the search for an exotic type of Higgs is guaranteed to be much more difficult; some exotic Higgs particles are not that hard to detect.  But you can’t say you’ve ruled out all the possibilities until you’ve gone exhaustively through the many difficult cases.

As an example: as was pointed out at least as far back as 1983, an exotic form of Higgs particle might decay to undetectable new particles over 90% of the time, delaying all standard search strategies for years, and requiring also a very difficult (but possible) search for an undetected Higgs particle recoiling against two observed jets.  Hard as this is, it is not the most challenging case, by a long shot.

I should add that when I say “ten years” that is of course my best guesstimate.  The precise time frame will depend on how well the LHC runs and at what energies and collision rates, and on how clever theoretical and experimental particle physicists are in getting the best out of the data.  I don’t think it will take fifteen years; I am sure it will take much more than five, because we won’t have enough data by then for the toughest cases.

Share via:


9 Responses

  1. Dear prof. Strassler, is there any upper bound in the degree of complexity of the Higgs variants and the difficulty of measurability of such variants? I mean, for any physical phenomena we can always look for a more rich, sophisticated and complex model that seems to better fit some aspects of the phenomenon, but we usually apply a simplicity principle in physics, and focus the research consequently: is there any Occam razor for the different theories embedding some kind of Higgs particle?

    1. GREAT question! Wow. So much to say.

      First, Occam’s razor is great when you have two sets of equations that describe the same phenomenon (e.g. Ptolemy’s cosmology vs. Copernicus/Kepler/Newtonian cosmology) and you want to decide which of the two to use. It has a bad record when predicting whether new phenomena will be present in nature or not. Its record in particle physics is particularly disappointing, as it would have led you incorrectly not to expect the muon particle, parity violation, the Z particle, masses for neutrinos, dark energy, and a host of other phenomena without which the world would be a much simpler place. So we have to be very careful. If we discover the Higgs particle and ten theories try to explain its features, we may want to pick the simplest one, along Occam’s lines. But if, come 2013, we are trying to figure out why we’re having trouble discovering it, that may not be the right way to go.

      Second, you must not confuse (and I, as an author, must try harder not to confuse you) the complexity of a Higgs variant with the difficulty of discovering it. As I always emphasize to students, a very simple Higgs variant can be vastly more difficult to discover than the simple vanilla Standard Model Higgs particle. (In fact I precisely emphasized this in the first 20 minutes of my June 18, 2010 lecture recorded at http://physicslearning2.colorado.edu/tasi/tasi_2010/tasi_2010.htm ) Manwhile, there are complicated Higgs variants that are actually easier to find, and would already have been discovered by now. How long it takes to find the Higgs has to do, obviously, with how complex the search strategy is, not how complicated is the theory that predicts it. And it is hard to justify applying Occam’s razor to an experimental search strategy!

  2. I do agree with you on this 10-year time frame. But, it is not demanded by the science but by the human psychic.

    The principle of least action goes way beyond physics and mathematics, and it applies to all areas. When a new manufacturing process is invented (such as Nature did for itself), it could be quite rudimentary, and it goes through a fine tuning process to reach the “least action” steady state. In this process, it can appear a bifurcation state, that is, it gets more complicated by adding a lot of bells and whistles. But, this bifurcation will converge to the final end, the least action steady state.

    With analogy of the most advanced “Wash machine” which consists of the following sub-systems.
    1. the hard-core wash machine, without any bells and whistles.
    2. a robot system to gather the dirty clothes from all rooms, with a dirty sniffing subsystem.
    3. a color sorting system
    4. etc.
    However exotic this system is, we will always find the debris of the hard-cord wash machine when it is bombed into pieces.

    At LHC, we are not trying to find out what are inside of protons. The p-p collision acts as bomb to break up the neighborhood spacetime sheet and to see what are hiding in it. If our bomb energy (the p-p collision) is not big enough to crack the exotic Higgs, then it is an all different story. If the energy is big enough, then we can always see the debris of the hard-cord Higgs (without the exotic-ness) even if it were no longer a standalone entity in the current state of universe evolution.

    Thus, if we did not see a hard-cord Higgs now, there is a little chance for seeing an exotic Higgs according to this principle of least action. However, in human psychic, we demand the last evidence from the last hole. Then, 10 years might still not be enough.

Leave a Reply


Buy The Book

A decay of a Higgs boson, as reconstructed by the CMS experiment at the LHC


The idea that a field could be responsible for the masses of particles (specifically the masses of photon-like [“spin-one”] particles) was proposed in several papers

POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON 04/16/2024

Although I’ve been slowly revising the Higgs FAQ 2.0, this seemed an appropriate time to bring the Higgs FAQ on this website fully into the

POSTED BY Matt Strassler

POSTED BY Matt Strassler

ON 04/15/2024