Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Particle overview

  1. Nov 7, 2006 #1

    wolram

    User Avatar
    Gold Member

    Last edited: Nov 7, 2006
  2. jcsd
  3. Nov 7, 2006 #2

    marcus

    User Avatar
    Science Advisor
    Gold Member
    2015 Award
    Dearly Missed

    in case anyone wants the abstract, just to get a taste before diving in
    http://arxiv.org/hep-ph/0611040
    Stable Massive Particles at Colliders
    M. Fairbairn, A.C. Kraan, D.A. Milstead, T. Sjostrand, P. Skands, T. Sloan

    " We review the theoretical motivations and experimental status of searches for stable massive particles (SMPs) which could be sufficiently long-lived as to be directly detected at collider experiments. The discovery of such particles would address a number of important questions in modern physics including the origin and composition of dark matter in the universe and the unification of the fundamental forces. This review describes the techniques used in SMP-searches at collider experiments and the limits so far obtained on the production of SMPs which possess various colour, electric and magnetic charge quantum numbers. We also describe theoretical scenarios which predict SMPs, the phenomenology needed to model their production at colliders and interactions with matter. In addition, the interplay between collider searches and open questions in cosmology is addressed. "

    I am ignorant regarding stable massive particles (SMPs). It seems that if they exist at all, they might have some connection to dark matter, assuming it exists.

    ==============
    I can't recommend this paper or offer discuss it with anyone because it is completely out of my ken. However one of the authors, Malcolm Fairbairn, is a growing blip on my radar. Fairbairn is at Perimeter Institute and also at Stockholm U. I was intrigued by the title of another recent Fairbairn paper
    http://arxiv.org/abs/astro-ph/0610844
    Shining light through the Sun
    Malcolm Fairbairn, Timur Rashba, Sergey Troitsky
    4 pages

    "It is shown that the Sun can become partially transparent to high energy photons in the presence of a pseudo-scalar. In particular, if the axion interpretation of the PVLAS result were true then up to 2% of GeV energy gamma rays might pass through the Sun, while an even stronger effect is expected for some axion parameters. We discuss the possibilities of observing this effect. Present data are limited to the observation of the solar occultation of 3C279 by EGRET in 1991; 98% C.L. detection of a non-zero flux of gamma rays passing through the Sun is not yet conclusive. Future experiments, e.g. GLAST, are expected to have better sensitivity."

    It is a way of testing some theory, if the theory is right then some of the gammaray in a GRB should shine thru the sun and be detectable. You could say he is doing phenonomology ----he is finding ways to kill off theories. Because if you do the experiment and there is a gammaray burst somewhere in back of the sun and you look towards the sun for gammaray, and you dont see any, then that shoots down the theory. OK. maybe the world needs more tests like this to clear the decks of theoretical clutter. (and it might also happen that you get a positive result)
     
    Last edited: Nov 7, 2006
  4. Nov 7, 2006 #3

    wolram

    User Avatar
    Gold Member

    The endless searches for this and that could be kicked into touch with a few good tests may be? it seems to me that everyone is searching for some
    particle or other, with no luck so far, may be in 2008 they wil, but if they do not?
     
  5. Nov 8, 2006 #4

    wolram

    User Avatar
    Gold Member

    From Wikipiedia

    Hypothetical particles

    Supersymmetric theories predict the existence of more particles, none of which have been confirmed experimentally as of 2006.

    * The neutralino (spin-½) is a superposition of the superpartners of several neutral Standard Model particles. It is a leading candidate for dark matter. The partners of charged bosons are called charginos.
    * The photino (spin-½) is the superpartner of the photon.
    * The gravitino (spin-3⁄2) is the superpartner of the graviton boson in supergravity theories.
    * Sleptons and squarks (spin-0) are the supersymmetric partners of the Standard Model fermions. The stop squark (superpartner of the top quark) is thought to have a low mass and is often the subject of experimental searches.

    Other theories predict the existence of additional bosons.

    * The graviton (spin-2) has been proposed to mediate gravity in theories of quantum gravity.
    * The graviscalar (spin-0) and graviphoton (spin-1).
    * The axion (spin-0) is a pseudoscalar particle introduced in Peccei-Quinn theory to solve the strong-CP problem.
    * The saxion (spin-0, scalar, R parity=1) and the axino (spin-1/2, R parity = -1) form together with the axion a supermultiplet in supersymmetric extensions of Peccei-Quinn theory.
    * The X boson and the Y boson are predicted by GUT theories to be heavier equivalents of the W and Z.
    * The magnetic photon.
    * Sterile neutrinos are introduced by many extensions to the Standard Model, and may be needed to explain the LSND results.
    * Mirror particles are predicted by theories that restore Parity symmetry.

    Magnetic monopole is a generic name for particles with non-zero magnetic charge. They are predicted by some GUT theories.

    Tachyon is a generic name for hypothetical particles that travel faster than the speed of light and have an imaginary rest mass.

    The preon was a suggested substructure for both quarks and leptons, but modern collider experiments have all but disproven their existence
     
  6. Nov 8, 2006 #5

    wolram

    User Avatar
    Gold Member

    Last edited: Nov 8, 2006
  7. Nov 8, 2006 #6

    wolram

    User Avatar
    Gold Member

    I know this may be a clumsy analogy, but we were running out of storage space at the factory where i work, i was told to use my judge ment and
    throw out any thing that is not wanted, well i did, i only kept the things i knew darned well that would be of use.
    Is this possible in theoretical models of our universe? it seems not, once any
    theory has been proposed it seems almost impossible to throw it out, shoot it full of holes and some will come along and patch it up, cut its head off and it will grow two more, is this advancing backwards?
    Yes shouts of shut up lowly uneducated person, well i am, but that is my out look at what you call science.
    I would concentrate on observable questions , such as,what is mass, what is energy, what is the photon, the electron.
    I can see that this will offend lots of people, well i am not sorry, but i do not in any way want to offend.
     
    Last edited: Nov 8, 2006
  8. Nov 8, 2006 #7

    arivero

    User Avatar
    Gold Member

    It is the experimentalist who holds the sword, while the theoretician milks the hydra.

    Well, perhaps this is exagerated. Theoreticians have rules for the model building.
     
    Last edited: Nov 8, 2006
  9. Nov 8, 2006 #8

    wolram

    User Avatar
    Gold Member

    May be the theoreticians should be hobbled by observables?
     
  10. Nov 8, 2006 #9

    wolram

    User Avatar
    Gold Member

    One last thought, if every possible particle has to be considered, may be particle accelerators should be built to last a million years.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?