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. 3

    Please explain something about the standard model

    I can't even begin to type out the entire equation for the standard model of particle physics, it is just so immensely long and I don't have the time, energy, or patience to do so. So please excuse the fact that I don't have the equation on here to show exactly what I mean. Now, I understand...
  2. G

    In what sense is the standard model enormously successful

    i've read a lot of authors claim that the SM is enormously successful, that it has passed every experiment with flying colors, etc etc, i won't bother with quotes because i think everyone agrees on that. yet I've also read that the amount of dark energy that the SM predicts is off by anywhere...
  3. Anymodal

    What is mass according to the Standard Model?

    Can someone explain me what is mass according to the Standard Model? I read that the Higgs boson "gives" mass to particles but I don´t understand what that means. :confused: Here's what I think I got so far : There is a field called Higgs field in all spacetime. It has a value for empty...
  4. S

    Summer school on Lorentz violating standard model extensions

    IUCSS Summer School on the Lorentz- and CPT-violating Standard Model Extension (SME) This program is going on now, at Indiana University. The title pretty much covers what the school is about. The SME simply takes the ordinary standard model and adds terms to the Lagrangian which violate...
  5. lpetrich

    The Standard Model from SO(32) superstrings?

    There are 5 types of supersymmetric string or superstring: I, IIA, IIB, HO, and HE. Their low-energy limits have forms of supergravity, and some of them also have gauge fields. Here are their gauge symmetries: IIA, IIB: No gauge field I, HO: SO(32) HE: E8*E8 The gauge fields are all...
  6. M

    Logarithmic corrections to black hole entropy, especially for the standard model

    Ashoke Sen has written a paper http://arxiv.org/abs/1205.0971 which uses path integrals in Euclidean gravity to compute "Logarithmic Corrections to Schwarzschild and Other Non-extremal Black Hole Entropy in Different Dimensions". Sen starts by listing several varieties of extremal black...
  7. arivero

    New papers on NCG and the standard model

    Well, not new insights, but at least new paper and a new face: http://arxiv.org/abs/1204.0328 Particle Physics from Almost Commutative Spacetimes by Koen van den Dungen, Walter D. van Suijlekom the veteran in the team is van Suijlekom and it seems that he is pushing forward with some...
  8. W

    B-L extension of the Standard Model

    i need what we mean by B-L extension of the Standard Model ?
  9. W

    The easiest way to standard model

    what is the the easiest way to learn standard model theory ?
  10. M

    What is the current status of particle physics beyond the standard model?

    In this forum, "Beyond the Standard Model", most of the discussion is about quantum gravity. But technically, even neutrino masses are "beyond the standard model". Some years ago, a paper was written, "The new minimal standard model", which self-consciously set out to describe a minimal new...
  11. B

    Which textbook for an introduction to the Standard Model?

    Hi. I am an undergraduate physics student and have just begun lectures on elementary particles and the Standard Model. At the moment I really know nothing about this branch of physics and am looking for recommendations on a textbook which introduces the subject well. Thanks
  12. J

    Is the Standard Model a particle theory or a field theory?

    just looking at the standard model, which describes a host of fundamental particles and bosons, one could assume that the SM is a particle model. however, most of what i read appears to indicate that particles are merely "excitations" or manifestations of a field, and it has been stated on this...
  13. K

    Question about the standard model equation

    http://nuclear.ucdavis.edu/~tgutierr/files/sml2.pdf Where is the = sign in this equation? Does it have one?
  14. F

    What is symmetry breaking in the Standard Model?

    I'm trying to figure out where symmetry breaking occurs in Feynman diagrams. I'm just free wheeling here, correct me where needed. But as I understand it, when you have a Feynman diagram where there is an interaction of one particle which decays to others, the incoming particle may obey one...
  15. T

    How do we arrive at Q = -1 from T3 and Y?

    Im reading Peskin&Schroeder, chapter 20, the one that describes the Standard Model. I got the general idea, symmetry breakings and so on, but I am getting quite confused when starting to go to the first mathematical details. My doubts are when, in eq 20.69 defines Q=T3+Y and then forces that...
  16. E

    Beyond the Standard Model (where *are* we going?)

    Alright, so I'm just getting through my first semester of QFT and while I'm not quite ready to step into anything really heavy, I'm close to the point where I can read introductory material on a technical level (like, I could probably start Zweibach's Strings for Undergrads). I've been reading...
  17. C

    Stress energy tensor in extended standard model

    Maybe this is the wrong topic for this forum, but i am reading the following http://arxiv.org/abs/hep-ph/9703464 Which is on CPT violation and the standard model. I do not understand how they get to equation (9), when they write down the stress energy tensor as \Theta\mu\nu=1/2 i...
  18. T

    Exploring the Standard Model: Is It Truly Fundamental?

    I was asked this question by someone else and wondered if I could get better answers here: Is it fair to say that the standard model for matter is basically descriptive, without any underlying understanding of what causes its structure? Can it be compared it to the periodic table of...
  19. S

    Nothing? (Beyond the Standard Model)

    It's a bit premature to conclude the LHC won't find Higgs or SUSY but... There are a few ideas kicking around that use knots (braids, strings, strands, knotted dimesnsions or whatever) to "explain" the Standard Model. One that catches the eye for its explicit particle mass calculations is...
  20. A

    Whats known to be wrong with Standard Model

    I know the Higgs has been causing some issues. Could we have a list of the problems/issues with the standard model, aside from the recent unverified neutrino issue. For instance, does anyone know where the spin of the proton comes from? Thanks
  21. R

    Logical inconsistency in standard model of entanglement

    I'm confused about a premise implicit in the standard QM model of entanglement, which seems logically inconsistent. I understand that entanglement arises when two or more particles interact in some way to become synchronized in their quantum states, which also must be indeterminate in terms...
  22. E

    Light building the standard model

    Something has bothered me for a long time about our model of light: that it has no mass. Just for a moment, forget what you know about light and let's call it the unknown, X, and suppose we want to model it. Here's what we know for certain: X has momentum, as seen by radiation pressure X...
  23. S

    Presuppositions of Standard Model?

    The lambda-CDM model predicts a nearly flat spatial curvature at scales larger than the the scale of homogeneity of the universe. The calculation of many of its parameters depend on the cosmic distance ladder which in turn depend on many observational techniques and statistical comparisons...
  24. J

    Questions on Redshift, Hubble’s Law, spacetime expansion and the standard model

    The current state of NASA’s version of cosmology is amazing to watch – According to modern cosmology, which NASA endorses, the Milky Way is moving through space at 600km/s and the Earth is moving through space at 30km/s and the sun is moving through space at 250km/s. So if we total up these...
  25. J

    On orbital mechanics and the standard model

    Some Questions on Lagrange Points – According to Wicki, a Lagrange point is The Lagrangian points are the five positions in an orbital configuration where a small object affected only by gravity can theoretically be stationary relative to two larger objects (such as a satellite with respect...
  26. L

    Can SO(3) be used for Poincare spacetime symmetry in the standard model?

    I'm a layman trying to understand the symmetries used in the std model. I understand that U(1), SU(2), & SU(3) are incorporated in the Lagrangians for internal symmetries. I've read that SO(3) is also used in the std model for Poincare spacetime symmetry. Is that true and if so, how is it...
  27. V

    Information Theory: Beyond the Standard Model

    What is the consensus here about Information Theory beyond the Standard model? The three fundamental theories of the universe, relativity, quantum mechanics, and the second law of thermodynamics all involve limitations on the transfer, accessibility, quantity, or usefulness of information...
  28. A

    Particles in the Standard Model - Mass & Size

    A quick question from a non-physicist and non-mathematician. Do the equations of the Standard Model (without the Higgs Mechanism and any other speculative theories) presuppose that all the particles have zero mass and zero dimensions i.e. are they purely "mathematical" points?
  29. M

    Exploring the Hamiltonians of the Standard Model in QFT for Scientists

    Hi all - as everyone knows, the fundamental laws of the Standard Model are almost always presented in Lagrangian form. Can anyone tell me of anywhere (such as a textbook) that I might find the Hamiltonians corresponding to these Lagrangians written out? (I'm confused on a couple of points and...
  30. W

    Standard Model calculation of the rest energy of a proton

    I was hoping someone could point me in the direction of the best way to calculate the rest energy of a proton. I am a complete noob with the standard model, so please be gentle. My goal is to compare a calculation of the energy which accounts for the quark structure of the proton versus E=mc^2...
  31. Andrew Mason

    Cosmology's standard model: is science becoming a belief ?

    Cosmology's standard model: is science becoming a "belief"? I recently made a partially tongue-in-cheek remark on this board about cosmology being a bit like religion. I thought, being April Fool's day, that I might get away with a provocative post. However, it appears that others did not...
  32. J

    Why is the standard model based on particles instead of fields?

    sort of a parallel thread to the current thread about "fields are more fundamental than particles". pretty much everything i have ever read about particles leads to the idea that what we perceive as particles is really just a manifestation of a field or of interacting fields. since we define...
  33. S

    Interesting topics in Beyond the Standard Model

    So basically I need to do a project on a topic in "beyond standard model" can anyone give me any theoretically interesting topics? I know this is a very loose question, but .. p.s I am a 3rd yr undergrad so nothing to crazy Only topics i can think of are just a standard search for a...
  34. tom.stoer

    Is a New Principle Necessary to Resolve Quantum Gravity and Unify Interactions?

    It is sometimes stated that new principles are required to solve the puzzle of quantizing gravity and harmonizing all interactions. Let me first list some known principles - quantization of classical theories; not really a principle, but a "program" - equivalence principle in GR - gauge...
  35. Astronuc

    The Standard Model and Beyond

    I was looking at a textbook on Introductory Nuclear Physics, and I came across this book: The Standard Model and Beyond By Paul Langacker http://www.taylorandfrancis.com/books/details/9781420079067/ It seems relatively complete. Anybody read this? Any thoughts/comments? What are other...
  36. B

    Guiding principles from the great physicists to take us beyond the standard model

    Perhaps if we focus on the common philosophy of the great physicists as to what physics is and ought be, expressed in their simple words reflecting infinite wisdom, we will be better prepared to advance physics beyond the standard model. Equations are more important to me, because politics...
  37. J

    Can we analytically continue the Standard Model?

    Why can't we analytically continue our model of the Universe past the Big Bang in a way analogous to how the Euler sum is analytically continued into the zeta function? If this were possible, this extension would encompass a larger phenomenon but would reduce down to our Universe when certain...
  38. G

    Standard Model with right-handed neutrinos

    Hey, I would like to ask you: I need have Standard Model with right-handed neutrinos. This is the simplest extension of SM which contains the Dirac and Majorana neutrinos. PR (right projection operator) coefficients should be nonzero. Is that enough? But what is their value? In the SM for the...
  39. FeDeX_LaTeX

    Understanding the Standard Model

    Hello; I apologise for any typing errors, as I am typing from a handheld device. However, there is something that I do not understand about the standard model. I have read that this equation is a 'lagrangian' but I do not know what this means or how to work with one. According to what I...
  40. C

    Standard Model Completely Wrong

    http://articles.latimes.com/2010/jul/07/science/la-sci-proton-20100708 Like the article says, if this experiment is true, the proton is 4% smaller than originally thought. If true, doesn't this mean we have to throw out everything we think we know about particle physics (standard model...
  41. H

    Standard Model Feynman Diagrams

    I have spent a while trying to get to grips with the building blocks used for constructing feynman diagrams, below is my attempt at a set of reactions, how am I doing so far? I don't think e^{+}e^{-}\rightarrow\mu^{+}\mu^{-} can happen since a gluon only interacts on particles with a...
  42. T

    Merging theoretical and experimental physics: the 'correct' standard model

    It is my understanding that the world of physics is split by a fast chasm into experimental and theoretical physics. The first time I told my father I wanted to be a physicist, he asked me “experimental or theoretical physics?” I thought for a second and responded “both!” He went on to explain...
  43. M

    The Standard Model (What Don't I know?)

    A big part of the theory of the standard model is that the major forces are mediated by the exchanging of elementary particles. So hypothetically, if we discovered some material that blocked the photon, for example, does this mean an object wrapped in this material would be unaffected by the...
  44. D

    Standard Model - strange feeling

    Does anyone share the same strange feeling I have about the Standard Model? The feeling that it had almost failed… So, let me present you Standard Model: 3 generations, 2 types of particles (quarks and leptons), dividing into 2 subtypes (upper/lower, lepton/neutrino), giving 12 fermions, or...
  45. J

    Higgsless Standard model

    "Higgsless" Standard model I realize we haven't been able to see the signal for a Higgs boson directly yet, but I have heard there is plenty of indirect evidence for the Higgs (in that it is needed in the model to match experimental results). My question is essentially: are all forms of this...
  46. B

    A Good Book on The Standard Model?

    I am looking for a decent book (probably a textbook) that covers the standard model in its entirety (not necessarily in its vast detail, though). I am a physics undergrad in my 4th year, so I'm looking for something that gets into specific math and theory, but obviously not something that would...
  47. inflector

    Complexity, The Standard Model and Higgs

    I've been reading most of the threads here in particle physics forum. Recently, I noted a couple of threads started by enotstrebor which were a bit impolitic. Nevertheless, they raised some issues which are similar to those I have myself with the Standard Model as well Quantum Mechanics in...
  48. P

    Redshift, Quantum Theory, and the Standard Model

    I am stuck on a few cosmological points I could use some help on. The first being "redshift" as an indication of inflation. To me red shift just seems like it's a result of the degradation of light quanta over long distances. Since light slows down in environments close to absolute zero...
  49. Spinnor

    Does loop quantum gravity hint at the Standard model?

    Have loop quantum theorists looked forward to how one might fit the standard model into loop quantum gravity? Thank you for any help.
  50. Spinnor

    Standard Model Lagrange Density, 2D vectors, Lattice Theory.

    In the article "The Lattice Theory of Quark Confinement", by Claudio Rebbi (Scientific American) there is a graphic representing the chromoelectric field. The caption reads: "Chromoelectric field is a gauge field similar in principle to the electromagnetic field but more complicated...
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