What is Standard model: Definition and 273 Discussions

The Standard Model of particle physics is the theory describing three of the four known fundamental forces (the electromagnetic, weak, and strong interactions, and not including gravity) in the universe, as well as classifying all known elementary particles. It was developed in stages throughout the latter half of the 20th century, through the work of many scientists around the world, with the current formulation being finalized in the mid-1970s upon experimental confirmation of the existence of quarks. Since then, confirmation of the top quark (1995), the tau neutrino (2000), and the Higgs boson (2012) have added further credence to the Standard Model. In addition, the Standard Model has predicted various properties of weak neutral currents and the W and Z bosons with great accuracy.
Although the Standard Model is believed to be theoretically self-consistent and has demonstrated huge successes in providing experimental predictions, it leaves some phenomena unexplained and falls short of being a complete theory of fundamental interactions. It does not fully explain baryon asymmetry, incorporate the full theory of gravitation as described by general relativity, or account for the accelerating expansion of the Universe as possibly described by dark energy. The model does not contain any viable dark matter particle that possesses all of the required properties deduced from observational cosmology. It also does not incorporate neutrino oscillations and their non-zero masses.
The development of the Standard Model was driven by theoretical and experimental particle physicists alike. For theorists, the Standard Model is a paradigm of a quantum field theory, which exhibits a wide range of phenomena including spontaneous symmetry breaking, anomalies and non-perturbative behavior. It is used as a basis for building more exotic models that incorporate hypothetical particles, extra dimensions, and elaborate symmetries (such as supersymmetry) in an attempt to explain experimental results at variance with the Standard Model, such as the existence of dark matter and neutrino oscillations.

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  1. J

    Basic question on QFT and the standard model

    The standard model comprises a particle model of reality, implying that every observable is either a particle of matter or a force carrying particle. QFT seems to imply that particles are merely manifestations of underlying fields - ie, particles are "ripples" in the field. if QFT is the...
  2. sweetser

    Exact Gauge Symmetry of the Standard Model

    Hello: The gauge symmetry of the standard model is written in authoritative places like wikipedia :-) as U(1)xSU(2)xSU(3). This would have 12 elements in its Lie algebra corresponding to one photon, W+, W- and W0 or Z, and the 8 gluons. I recall reading discussions that such a...
  3. A

    Non-standard question about the Standard Model

    (I have a question about the Standard Model in spite of the topic title. It seems the right place to ask it after perusing the other forum topics. Also, I had erroneously posted this to the "Advanced Physics Forms" where the crickets are still chirping. It's not my intention to cross post...
  4. U

    What is the purpose of Faddeev-Popov ghosts in the standard model lagrangian?

    Does anyone have a high resolution picture of the standard model lagrangian? i want to put it on a t shirt and give it to my math teacher who worked at Bell Laboratories for 10 years and knows just about everything about physics and math. P.S. i only think its called the standard model...
  5. N

    What's the Standard Model of Particle Physics

    I'm trying to figure out what the standard model of particle physics is, what is included, who decides what's included, and how one would know when a new concept/theory is included or possibly rejected. It would be great to have a list of recent additions or experimental confirmations. Must...
  6. E

    Exploring the Standard Model with a Typical Scientist

    A typical Scientist trying to get Standard Model to work. http://home.comcast.net/~erica.ramsey/StandardModelAndScientists.jpg
  7. R

    SU(2) in Standard Model and SUSY extensions

    If you have doublet Q=(u,d) , and want to give the u-quark mass, you have to connect it to the Higgs VEV H=(\nu,0) doublet through the adjoint opertion: H^{\dagger i}Q_i Connecting H and Q through the Levi-Civita symbol e_{ij} : e^{ji} H_{ i}Q_j results in d-quark mass, not u-quark...
  8. D

    Is the Standard Model of Physics Aligned with Bohm's or Bohr's Interpretation?

    Is the Standard Model of physics more aligned with Bohm's or Bohr's interpretations? And if more aligned with Bohm, then why is the Copenhagen model so highly regarded and not Bohm's?
  9. O

    M Theory: Exploring Gravity's Necessity in the Standard Model

    How does M theory force gravity as a necessity when the standard model couldn't fit in gravity?
  10. wolram

    The Emergence of Beyond the Standard Model: What We've Learned

    When did beyond the standard model become an acceptable topic, and what has it added to our knowledge?
  11. B

    How Do Standard Model Symmetries Influence Theoretical Physics?

    1. The Standard model is an SU(3)xSU(2)xU(1) symmetric theory. To me this means that if you choose any 3 members of the groups and act on the Lagrangian, it is invariant. However, not all terms in the Lagrangian have something for a group member to act on, for example terms that don't involve...
  12. J

    How does Dark energy fit into the standard model?

    At this point, I am rather confused about the concept of DE, and even why it is called DE since it does not seem to fit into what the concept of energy is. but my question is where/how does DE fit into the standard model? thanks.
  13. K

    Standard model coupling strengths

    Hi guys, Where can i find the most up to date (accurate) values of the standard model coupling strengths at the mass of the Z boson? Thanks Karnten07
  14. K

    Standard model coupling strengths

    Hi guys, Where can i find the most up to date (accurate) values of the standard model coupling strengths at the mass of the Z boson? Thanks Karnten07
  15. T

    Intuitive problems with the standard model

    I don't claim to be an expert of any kind, and most of these "problems" I see are probably just due to my own pre/misconceptions, but nonetheless: 1) As we get closer and closer to the Big Bang event, the universe is supposed to get hotter and denser until some sort of "infinity" where the...
  16. K

    The standard model, a couple of q's

    I have a couple of questions about the standard model: 1.) I read somewhere that the standard model describes 3 closely related Yang-Mills systems, but i thought yang-mills systems were non-abelian whereas U(1) is abelian. So is the statement false or have i misunderstood? 2.)Why do i see...
  17. D

    Effects of the Variation of the Parameters of the Standard Model

    Hi I know that our world is quite unstable and minor changes in these parameters could make the existence of life impossible. However, I am interested in what exactly is going to happen if we start to increase/decrease any of 30 parameters. It is interesting how well-tuned these parameters...
  18. WaveJumper

    The nature of particles in the Standard Model vs String Theory

    Neutrinos are elementary particles that have the ability to pass through any matter. Billions of them pass through our bodies every second. Billions of them pass through the Earth and exit on the other side unaffected. They can pass through stars and travel to the other side of the universe...
  19. S

    Finding the Standard Model of Physics

    Where can someone find the entire standard model?
  20. J

    What is wrong with the standard model at 1 or 2 TeV?

    Every now and then one reads that the standard model does not work for energies above 1 or 2 TeV. Can anybody explain where this statement comes from? As far as I understand, there are no deviations of the standard model form experiment. There is only the issue of Higgs mass being...
  21. marcus

    MDM (a minimal extension of standard model) and PAMELA

    A proposed MDM goes beyond the standard model in a minimal way, so as to produce a candidate for dark matter. Here is story from Nature News: http://www.nature.com/news/2008/080902/full/455007a.html Here is a key excerpt: ==quote== ...It now seems that some physicists have taken...
  22. J

    Standard Model of Particle Physics

    Does anyone know where to find the standard model of particle physics shown by Brian Cox in his LHC TED talk (found around 6:35 here: http://www.youtube.com/watch?v=_6uKZWnJLCM)? I'm looking to print out the equation but can't find it anywhere. Thanks
  23. R

    PBS Ghost Particle neutrinos showing Standard Model wrong

    PBS “Ghost Particle” neutrinos showing Standard Model wrong Tonight and tomorrow (Sunday), PBS television is rebroadcasting “The Ghost Particle” on the neutrino work by John McCall and Ray Davis that showed the Standard Model Theory was wrong and made incorrect predictions about neutrinos...
  24. marcus

    Uniqueness of deSitter spacetime and the Standard Model (hints from two papers)

    Loll will deliver three one-hour talks at Oporto in mid July Here's the abstract Renate Loll, Quantum Gravity from Causal Dynamical Triangulations Abstract: I discuss motivation, implementation and results of the nonperturbative approach to quantum gravity based on Causal Dynamical...
  25. arivero

    Is the Standard Model a M-theory?

    M theory is an 11 dimensional theory which in some limits can reproduce all the five 10 dimensional string theories, and also 11D supergravity in some other limit. The mantra of string theory has been, for years, "we do not know what M-theory is". On the other hand, 11 dimensional space is...
  26. J

    Dark matter and the Standard Model

    At this point, i am not yet convinced that enough data is in on the subject of dark matter/dark energy to support expansion of the standard model to include them, but, then, i am just a lowly layperson... How do you guys see dark matter and dark energy fitting into the standard model? how...
  27. D

    Exploring the Standard Model at the LHC

    So, what will we see at the LHC if the Standard Model is all that there is to physics at this energy scale? What if there is no supersymmetry, no strings, no loops (or at least no emergent behavior that would be seen here)? Are we going to be able to tell if those theories are false pretty...
  28. L

    Tachyons challenge the Standard Model?

    Just looking for ideas if it does. I've looked at closed string tachyon condensation and it apparently excites the graviton as it's also closed string and this can warp spacetime. I (think) see a flaw in symmetry here as if I were on earth, feeling the gravitational field strength, I'd...
  29. G

    How to teach Isaac Newton the standard model and cosmology

    You are given a chance to fly back in time with no worry over changing history in bad ways. Knock knock and you enter a college looking for famous Isaac Newton, age 45, in person. He's a real fun in every way - mechanics, theory of gravity, celestial mechanics, calculus, the queen. Also he...
  30. K

    Unification of String theory and the Standard Model

    I was looking at a page in wikipedia about well-known theoretical physicists, i stumbled across the physicists Dimitri Nanopoulos and John Ellis. It mentioned that they both worked together to unify string theory and the standard model and quote Does anyone know if they were successful in...
  31. J

    Dark matter/virtual particles in standard model?

    dark matter/virtual particles in standard model?? where do dark matter, dark energy, and virtual particles fit in the standard model? if those three mystifying concepts are necessary to explain the universe and its operation, why are they not included in the standard model? IMHO, all three...
  32. H

    Will Detection Of Higgs Boson Complete Standard Model?

    We are pinning high hopes on LHC experiment. One of the expected results of the experiment is detection of Higgs Boson that would complete the standard model. In fact, discovery of Higgs Boson would complicate the theoretical issues because then we will need to find out.. a. origin of Higgs...
  33. E

    Lerning the Standard Model and some question about QM

    Hi I used the last few month two make me familiar with quantum mechanics and read two books. The Feynman lectures on physics and Principles of Quantum Mechanics (R. Shanker). I think I have no problems with the bra-ket notation and solving the Schroedinger equation for some simple particle...
  34. E

    List of fundamental equations and constants of the standard model

    Hi Is there anywhere a list of all constants (with their values) and fundamental equations (which can not be constructed from any other equations) of the standard model? thx einKI
  35. CarlB

    Category theory and beyond the standard model

    Kea tells me that a good first book to read to learn category theory is Sets for Mathematics $45 F. William Lawvere and Robert Rosebrugh Advanced undergraduate or beginning graduate students need a unified foundation for their study of mathematics. For the first time in a text, this book...
  36. M

    Exploring Theories of the Unifying Force Beyond the Standard Model

    Have there been any theories in recent decades that suggest one? Or more? I know it may seem unnecessary or even frivolous, but theories beyond the standard model are, after all, grappling with issues like how the entire universe and its four forces came to exist. Has anyone postulated a fifth...
  37. S

    A model behind the Standard Model?

    Two interesting papers by Chan and Tsou on the hep-th arxiv: hep-ph/0611363 Title: Higgs Fields as Vielbeins of Internal Symmetry Space Authors: H.M. Chan, S.T. Tsou Comments: 24 pages An earlier suggestion that scalar fields in gauge theory may be introduced as frame vectors or...
  38. S

    What Lies Beyond the Standard Model in Particle Physics?

    "Beyond the Standard Model" hep-ph/0611279 Beyond the Standard Model Authors: Dmitri I. Kazakov Moscow 2006 Report-no: 2006 Review of recent developments in attempts to go beyond the Standard Model is given. We concentrate on three main unresolved problems: mechanism of electroweak...
  39. marcus

    New Connes: Gravity and the standard model with neutrino mixing

    I put a notice of this earlier today in the QG links thread https://www.physicsforums.com/showpost.php?p=1134904&postcount=529 https://www.physicsforums.com/showthread.php?p=1134904#post1134904 This thread is in case anyone wishes to discuss the paper: http://arxiv.org/abs/hep-th/0610241...
  40. B

    QCD, a part of standard model?

    How is it not an exactly accurate understanding that QCD is a part/sector of the standard model of particle physics ? Or, it actually is?
  41. B

    String theory & standard model & black hole entropy

    how many propreties of particles of the standard model has lqg been able to describe within its conceptual framework, as opposed to string theory? recently i posted "lee smolin & standard model" evidently loop quantum gravity might be able to model some elementary particles properties...
  42. B

    Lee Smolin's LQG may reproduce the standard model

    http://www.newscientist.com/channel/fundamentals/mg19125645.800 sounds like string theory, all particles from vibrations. how successful has this theory been in comparison to string theory, on particle physics? "physical particles may seem very different from the space-time they inhabit, but...
  43. wolram

    Collection of known scientists that are beyond the standard model

    No crackpot stuff her please, i would like a collection of known scientists thoughts that are beyond the standard model, Hawking has some good stuff :zzz: what are your favourites?
  44. A

    Professional Ideas Beyond the Standard Model of Dark Matter

    Berkeley writes : " Note that the dynamics of the Universe are not determined entirely by the geometry (open, closed or flat) unless the Universe contains only matter. In our Universe, where most of Omega comes from dark energy, this relation between the mass density, spatial curvature and...
  45. R

    What is the uncertainty principle for Standard Model particles?

    Hello Folks! Though I have written my own paper (http://arxiv.org/abs/math.DG/0605709) , I am still a novice in Standard Model. Therefore, I have some questions for experts. The modules squares of the fermion wave functions are interpreted as the probability densities for the particles to...
  46. R

    Is the Standard Model overly speculative ?

    Is the Standard Model overly speculative ... Or does it need intelligent, freer interpretation ...?-- cf "One part of the Standard Model is not yet well established. We do not know what causes the fundamental particles to have masses. The simplest idea is called the Higgs mechanism. This...
  47. marcus

    Quantum Gravity and the Standard Model (Sundance + PI)

    http://arxiv.org/abs/hep-th/0603022 Quantum Gravity and the Standard Model Sundance O. Bilson-Thompson, Fotini Markopoulou, Lee Smolin 12 pages, 21 figures "We show that a class of background independent models of quantum spacetime have local excitations that can be mapped to the first...
  48. E

    Standard Model help requested .

    Standard Model help requested... Hi all, I hope this is the appropriate forum for asking about the Standard Model of particle physics. My formal education covered only chemistry, semiconductor physics, classical physics, special relativity, and introductory quantum mechanics. So my...
  49. L

    Is the Higgs Field Essential for the Standard Model's Consistency?

    I had my first lecture on the Standard Model today. The lecturer presented the Lagrangian for the Standard Model, which took up two slides. However, it contained terms that referred explicitly to the Higgs field, whereas I was under the impression that the Standard Model didn't need the Higgs...
  50. M

    Muon g-2 and the Standard Model: Updates and Questions

    A few years ago BNL did some experiments measuring muon g-2. At the time there was a significant enough difference from the calculations based on the Standard Model to raise questions about SM. Since then I've seen papers indicating that SM was probably OK, with the discrepancy being due to...
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