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Higgs boson detection is it possible as of 2008

  1. Dec 10, 2007 #1
    The Higgs boson introduced by P. Higgs (insert --> the spontaneous symmetry breaking with the gauge theories was also constructed by Robert Brout & Francois Englert) one question I do have is on the dynamics involved dealing with this concept - is it truly possible to detect the process by decay of other particles (if this is not actuate please correct) & truly know it is the dynamics of the predicted Higgs field?

    Not wanting to be naive - my concern is in using the instruments to detect the decay of other particles can this truly be reliable in the data received to identify the field.

    Example when CERN/LHC begins to produce data because of the complexity of the entire facility can be with certainty's be sure that the information has not be corrupted due to outside influences?

    I believe I understand the laws/foundations that I must use in my field to the best of what abilities I have been given intellectually (I am limited due to the fact the more I research/read/see it seems the less I know & understand).

    This is just a question not a challenge to the undertaking of CERN/LHC & the brilliant men & women working on the project? If it is possible and we do not find it my desire is that it will open many doors of possibilities for research in P.Physics

    Could someone please help me in this situation from which extrication is difficult at best? If there is another post that has covered this in detail would you direct me to the post, I have not found it in this forum & it could be due to over site on my part.

  2. jcsd
  3. Dec 10, 2007 #2
    I find it hard to understand what exactly you are asking for - and judging from the replies you got so far (=none) I am probably not the only one. A few comments, though:

    - You can never be sure that everything will work fine. But I am pretty sure that every piece relating to LHC (meaning hardware, software, physics predictions, detection and reconstruction algorithms, results, dunno what else) is/will be checked very carefully. Additionally, LHC has more than one detector. And the different detector groups are kept relatively seperated from each other. It's not that LHC is the first collider experiment ever performed, and past experiments came up with great results. For the accelerator itself, I (naively) don't see any "this could give some completely misleading results"-problem - you either have enough proton collisions at sufficient energy or not.

    - The Higgs-boson is not looked for as a decay product of other particles (at least not in any process that I was aware of). It's the other way round: The events detected at the detector are searched for what could be decay products of a Higgs-boson.

    - What is your field?

    - If we won't find a Higgs-boson, I think alternative models exist (more precisely: I am pretty sure of that, but I don't know any myself).

    - More generally (not related to the topic, but I sometimes get the feeling this point should be stressed): There is really no shortage of theoretical models that could be investigated.

    - Higgs-searches are (mostly due to the Higgs-boson being the most prominent particle to look for) pretty sophisticated. It's not a simple "we found decay products fitting to an intermediate 120 GeV particle - hooray, we found the Higgs!". A possibly interesting read is the following talk by Michael Duehrssen: link
    Last edited: Dec 10, 2007
  4. Dec 10, 2007 #3
    Timo, thank you for your constructive criticism I will not post until the question can be stated with clarity.

    Diplomatically you have explained to me that sleep deprivation has taken its toll - I will rest now.

  5. Dec 10, 2007 #4


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    According to my friend that does diploma work about simulating Higgs production, says that there exists different models, and each model has a set of higgs bosons. And also that the higgs boson only can explain the mass of the gauge bosons of the weak interaction (W,Z). I have no idea =)
  6. Dec 11, 2007 #5
    Yes. As soon as the empty set counts as a set, this statement is kind-of trivial (kind-of because you have to define what a Higgs-boson is).
    As a prominent example: The minimal supersymmetric extension of the SM, the MSSM, requires a 2nd Higgs-doublett (still speaking about the field content before EW-breaking, here) with opposite U(1) charge. This doubles the degrees of freedom of the Higgs-fields from 4 to 8. Under EW breaking (where both of the doubletts obtain a non-vanishing vev,) again three of the degrees of freedom can be redefined into the then-massive interaction particles of the weak interaction, this time leaving 5 remaining degrees of freedom: Two scalar Higgs bosons, an electrically charged one (counts 2 dof) and a pseudoscalar one. There, the lightest scalar is the "SM-like" Higgs-boson that is looked for.
    Still, I'm pretty sure that completely higgsless models exist (they would probably not count as BSM, then). If someone knows a bit more about these models, please comment on them.

    Out of personal interest: Is he/she using Pythia or something else?

    In the SM, the Higgs-field is the mechanism that allows for observed masses of the W and Z - a native mass term for gauge bosons would violate gauge invariance of the action. While the SM would not work without the Higgs-mechanism, that does imho not necessarily mean that there was no other way to get gauge-like vectorbosons (W and Z) without it - there could be some other way to tackle the problem of the massive W and Z. And well, like said: There are higgsless models (although I dunno how they work). The model-builders usually don't completely ignore basic things like W and Z masses.
    Last edited: Dec 11, 2007
  7. Dec 11, 2007 #6


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    My friend does one with the supersymmetric extensions to SM.

    This is the gruop he works for: http://www3.tsl.uu.se/thep/

    Dont know if he uses Phytia for his project.

    The professor (Gunnar Ingelman) has worked with / knows the creator to Phytia (Torbjörn Sjöstrand) [If I remember correct].
  8. Dec 12, 2007 #7


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    I guess Technicolor models would belong to this class.
  9. Dec 12, 2007 #8
    I am using every precaution to assimilate what has been posted thus far. Your references and comment have been clear and understandable.

    I must confess there is a few laws/mathematical approaches that I must work through to my satisfaction of understanding.

    I just wanted to thank you for the information given and I will be sure when I am not in the field of dreams with my comment - to the best of my ability it will be understood by all.

    Timo, has given me very sound advice in which I will follow.
  10. Dec 12, 2007 #9
    I don't think I gave any advice.
  11. Dec 21, 2007 #10


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    It is possible because, if the Higgs mechanism is the correct description of EWSB, then there should be a particle associated with it (the Higgs boson), the properties of which have been studied extensively for a number of years.

    A big part of making these measurements has to do precisely with your question: i.e., a lot of effort goes into making sure that the uncertainties in the measurement are well understood. People try to think in advance all possible sources of "fake signals", like how many cosmic rays arrive to the cavern (the detectors are placed in caverns about 300 feet below ground level), how often can these cosmics have enough energy to look like the particles we are looking for, how natural background radiation can influence the search, etc.

    Not only that. Also, the first year or so of data taking (which is A LOT of data) will be scrutinized intensively, just to "rediscover" the currently known physics. This is an unavoidable step that every new big experiment has to make before any claims about new physics can be taken seriously.

    It sure is a very complex facility, but bear in mind that, to a good extent, this complexity is due precisely to the goal it seeks, which is to provide the cleanest possible signals in searches for new particles.

    The particle beams will be circling in probably the largest volume of high vacuum made in history (in order to make things as clean as possible), and will collide amidst very strong magnetic fields created by superconducting magnets. The reason for the magnets is also to bend the trajectory of charged particles so that we can better identify them.

    Moreover: a discovery cannot be claimed on the basis of a single event; depending on the search, you may need between tens and hundreds of Higgs-like events to claim anything. Also, in particle physics, you can only claim a discovery if you prove statistically that your signal has an extremely low probability of being a fake; here "extremely low" means 2.8 in ten million... i.e., once you find something, you should prove that, if you did the experiment 10 million times in a Higgs-less universe, less than three of them would have a signal as strong as what you find.
  12. Dec 21, 2007 #11


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    In addition to what ahrkron has said, note also that in all of these collider facilities, there are more than just one type of detectors. The Tevatron had CDF and D0, which not only compliments each other, but in some ways, compete with each other. The top quark discovery was confirmed both by CDF and D0, with each having different ways and probing different interaction channels to detect its the quark's existence. They both have to independently confirm not only the presence of the top quark, but also they properties of it such as its mass.

    The same will be true with the LHC. You will see several different detectors looking for various properties of the Higgs via different mechanisms. If ATLAS sees it but CMS doesn't, it's not going to be convincing.

  13. Dec 21, 2007 #12
    All, I have been doing my best to study the different perspectives from the facilities you have mentioned. The detectors mentioned some I am familiar with. I have overlooked so much formerly I care not to repeat if possible I have not checked the data now available from a lab in the USA.

    I check in weekly, but unless I have something of worth to express I would not want to take away from others who would need your attention.

    Happy Holidays to All...and thanks.
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