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. PeterDonis

    Antiparticles of Standard Model gauge bosons

    From a recent thread: Is this true of gluons? Doesn't the color charge invert under CPT? (For example, a red-antigreen gluon's antiparticle would be a green-antired antigluon.)
  2. Kevin McHugh

    Exploring the Basics of the Standard Model

    Hi all, I am new to the forum. I have a BS in Chemistry (1984). So I remember a little quantum mechanics. I am trying to wrap my head around cosmology. I started studying GR on my own about a year ago. It took me almost that long to understand tensors. This invariably lead me to start reading...
  3. atyy

    Status of lattice standard model

    What is the "consensus" status of the existence of a lattice standard model? These two sets of notes don't seem to be in agreement. Wiese's 2009 notes http://www.itp.uni-hannover.de/saalburg/Lectures/wiese.pdf say "Thanks to a recent breakthrough in lattice gauge theory, the standard model is...
  4. N

    Higgs particle and standard model Higgs particle difference?

    Hey physics enthusiasts, I have been reading and watching various videos, which talks about the possibility that the Higgs particle which was discovered by collisions in the large hadron collider(LHC) may not be the standard model Higgs particle. What does this mean? What is the difference...
  5. e.bar.goum

    Why do high energy accelerators have to be so large?

    Today is an exciting day, for today will see a new record for the highest energy collisions at the LHC - stable 13 TeV collisions for new physics, signalling the start of the new physics program at the LHC! There are a few ways you can keep track of progress throughout the day. The LHC status...
  6. Q

    Excluding the Standard Model from Dark Matter?

    Usually, I like to bring up Dark Matter whenever I discuss cosmology or astronomy with someone, and whenever WIMPS (Weakly Interacting Massive Particles) are brought up, the person usually responds saying, "but there is no particle on the Standard Model that possesses all the particles of a...
  7. ohwilleke

    Is Isospin Conversation Required In The Standard Model?

    A new experimental result from BESIII finds that there is isospin violation in the decays of J/Psi mesons in a path involving scalar mesons (with a narrow width in tension with world averages) and notes that a previous experiment found isospin violation in another decay chain...
  8. S

    Lagrangian of Standard Model Deduction

    Does anyone know where can I find the deduction of all terms of the updated SM lagrangian? Although I have already looked at some lagrangians and theories like local gauge invariance, Yang-Mills theory, feynman rules, spontaneous symmetry-breaking and others, I wanted to see the deduction and...
  9. U

    Why don't a charm-anticharm meson decay to pair of leptons?

    If you consider the ##\chi_0 ## with a mass of ## 3.4 GeV/c^2## meson, why doesn't it decay to a pair of charged leptons? Technically it is possible though the weak interaction (Z boson) or EM interaction, right? Is it because it is so heavily suppressed because the strong interactions are...
  10. Breo

    Standard Model Anomalies: right-handed neutrinos

    If we consider de right-handed neutrino there would be more anomaly-free solutions than hypercharge for a U(1)?
  11. Breo

    Basic Questions on the Standard Model

    1) The Feynman Diagams which provide the dominant contributions are just those with the greater amplitudes? I have the doubt because I read could be more dominant contributions for a single process and I am not sure amplitude would be the same for them. 2) How to compute the cross section in...
  12. A

    Necessary knowledge of standard model for string theorist

    I wasn't sure whether I should post this question in this category or "High Energy, Nuclear, Particle Physics", but I decided to post here, since I want to get opinions from the people who are studying the topics discussed in this category, not the experts on standard model or particle physics...
  13. Breo

    Basic question on the pertubative Standard Model

    Dear all, how to 100% know if a process is allowed in standard model? And when a process is allowed, how to know what diagrams contribute, and what of those are the dominant ones? Thank you in advance.
  14. G

    ¿Is there a minimal standard model for ZFC?

    ¿Is there a minimal standard methamatematical model for Zermelo set theory in the sense that the other models contains this model ?
  15. F

    What is responsible for force in the standard model?

    It is touted that modern physics has discovered what is actually responsible for force which are particles. Yet, the force responsible for EM is "virtual" particles and then you have the "W" particle in Electroweak. So it seems the issue is not all that clear. I know how the math works, but I am...
  16. resurgance2001

    Derivation of standard model lagrangian

    What's the simplest, most direct way to derive the lagrangian of the SM? I saw earlier today: L[S M] = L[Dirac] + L[mass] + L[Gauge] + L[Gauge/psi] That seems like a good starting point. I like it because it says the SM Lagrangian is simply the sum of four lagrangians. The next step...
  17. L

    CC Problem Beyond the Standard Model

    Which of the following do you prefer as possible solution to the cosmological constant problem or why QFT computes vacuum energy density that is 120 magnitude more than from observational data? Sometimes I think the metric (1.a) needs to change, but on other days I think QFT needs to change...
  18. B

    Question on the Standard Model

    I read in a magazine (namely Scientific American) that the Standard Model successfully combines Quantum Mechanics with General Relativity, but I also remember reading in The Elegant Universe that the Standard Model fails to do so. What's true and what's not?
  19. J

    Standard model, mass prediction

    Hi, I've read on the cern website that the standard model does not predict that matter inherently has mass, if this is the case how does the model predict particle masses and also why doesn't it predict that matter inherently has mass? Thanks.
  20. T

    Re-Examining Black Holes and the Standard Model

    I was thinking about this and either I have a misunderstanding of black holes or they are simply not how the standard model proposes them to be. Lets start out by setting a few a statements from the standard model that you agree with. If you disagree about any of these points please comment so...
  21. C

    Understanding Kaon Notations on Chart Before Standard Model

    I was looking at this old chart (before the standard model was completed) and this thing with Kaon notations was confusing. So I understand that the top right number on a particle denotes charge, but what is subscript? Does that denote the number, as in which exact particle it refers to? Because...
  22. U

    Renormalizability of the Standard Model

    Why is it such a big deal? According to the "modern" (Wilsonian) viewpoint, non-renormalizability is not such a "sickness" of a quantum field theory, as long as one adopts the viewpoint that the theory is not UV complete, aka, the theory is simply an effective field theory with a finite cut-off...
  23. M

    Symmetries of the Standard Model: exact, anomalous, spontaneously brok

    There are a number of possible symmetries in fundamental physics, such as: Lorentz invariance (or actually, Poincaré invariance, which can itself be broken down into translation invariance and Lorentz invariance proper), conformal invariance (i.e., scale invariance, invariance by...
  24. tlnarasimham

    In the standard model gravitron is a particle but Higgs boson is not?

    In the standard model gravitron is a particle but Higgs boson is not. The Higgs field causes particles to acquire mass. Mass generates a gravitation field. Is gravitron is in any way related to Higgs boson? Is the Higgs field any way related to gravitation field?
  25. L

    How do D-Brane arrangements affect particle masses and the standard model?

    Hi. I've been reading that if one places a Dp brane in a 10d space then it's possible to have a string with [11] Chan-Paton index i.e. a string that starts and ends on the same Dp brane. Since the separation of the brane with itself is 0, this string corresponds to a massless particle. Why is...
  26. tom.stoer

    Standard model gauge anomaly cancellation

    There are quite subtle gauge anomaly cancellations in the standard model. Does anybody know a good summary about the algebraic constraints for number of fermions per generation, value of electroweak charges, etc.?
  27. S

    Spontaneous symmetry breaking in the standard model

    In the standard model, the Lagrangian contains scalar and spinor and vector fields. But when we consider spontaneous symmetry breaking, we only account for the terms contain only scalar fields, " the scalar potential", in the Lagrangian. And if the scalar fields have vacuum expectation value...
  28. Spinnor

    Adjust parameters of Standard Model so only photons, e-, e+ remain?

    Could you have a hypothetical universe with only photons, electrons, and positrons by adjusting the parameters of the Standard Model to eliminate all the "other" stuff? If so is String Theory flexible enough to model a hypothetical universe with only photons, electrons, positrons, and...
  29. V

    Database of theories beyond the standard model?

    I am a programmer and physics fan. A speaker (Lawrence Krauss?) at https://origins.asu.edu/events/great-debate-parallel-realities-probing-fundamental-physics (not on youtube yet) said physics theories beyond the standard model are an under-determined problem. There are 7,000 theories that fit...
  30. C

    Places to study Physics Beyond The Standard Model.

    I am a MSc student and I am looking for a place to do my PhD in Physics Beyond the Standard Model (Theoretical side). Any suggestions for a place to apply?. I know that there are the traditional elite places like MIT, Standford, Berkeley and so on but I am looking for other suggestions given...
  31. Q

    Symmetry Groups of the Standard Model: SU(3) x SU(2) x U(1)

    I have a question regarding symmetry groups. I've often heard that the Standard Model is a SU(3) x SU(2) x U(1) theory. From what I understand these groups contain the symmetries under which the Lagrangian function is invariant. If so, what does every one of the 3 groups above contain (what...
  32. N

    How are dark matter, general relativity, and standard model related?

    In other words, can dark matter be reconciled with GR without drastically changing the idea that force is due to space-time curvature? and in the case of the standard model is there any thoughts of how the force of dark matter is transmitted via the exchange of a particle? It seems that this...
  33. A

    Standard model + symmetry questions

    Homework Statement 1) Which U(1), SU(2) and SU(3) gauge invariances are implemented in nature according to the Standard Model? What are the related quantum numbers? 2) The SU(2) symmetry is referred to as a non-abelian symmetry. What does this imply for the interactions between the force...
  34. mfb

    Deviation from Standard Model observed at LHCb (B->K* mu mu)

    As usual, the interpretation is still unclear, but I think it is an interesting effect. LHCb studied the angular distributions in the decay ##B^0 \to K* \mu \mu## and presented the result at EPS2013. In one variable (called P'5) in two bins, a large deviation was found (3.7 sigma in one bin)...
  35. S

    Wave-particle duality in the Standard Model

    I posted this question in an another forum but I didn't receive any answers, so I'll post it here again: Do all the fundamental particles in the Standard Model (61 fundamental particles) exhibit wave-particle duality? From my understanding, a photon acts more like a wave than it does a...
  36. N

    Interpretation of QED in the Standard Model

    Three related questions on which I could use some help: a] In another thread, Bill_k posted something like: "Electrons, being charged, could exchange energy by exchanging a virtual photon." ok, yet I thought electrons usually interacted via the EM field ['real' photons]... So how...
  37. M

    Beyond the noncommutative standard model

    http://arxiv.org/abs/1304.8050 Beyond the Spectral Standard Model: Emergence of Pati-Salam Unification Ali H. Chamseddine, Alain Connes, Walter D. van Suijlekom (Submitted on 30 Apr 2013) I have a few questions about this paper... How good is "almost uniquely"? i.e. it would be good to see...
  38. B

    Higgs, neutrinos, and standard model status

    I've always understood that the "formula" for the Standard Model is SU(3) × SU(2) × U(1). Since the discovery of the Higgs boson, and observations of neutrino flavor oscillations, has that formula been revised, or is it still the same?
  39. T

    How big is the standard model?

    How many internal degrees of freedom does it have? In other words, how many 4d real functions do we have to specify in configuration space (i mean the space we use in Path integration) in order to specify a state? It is difficult to state the question, so, in order to be more precise, the...
  40. J

    Question about the number of particles in the standard model.

    Hi, I was just wondering why there are a finite number of fundamental particles in the universe. Why is it that when cern collide particles, the same particles are formed every time. Its like putting a hammer to a concrete block and every time you do so, the same chips with the same shape and...
  41. N

    Would a Universe be considered part of the standard model?

    From my basic understanding of the standard model it tries to identify the different kinds of particles, understand their functions and their subsequent sub atomic particles. But as particles and forces break down into smaller components, do they also build up into bigger components? For...
  42. R

    Any recommendations for books or articles on the Standard Model?

    I'm an undergrad physics student and have to write an essay on the Higgs boson and the future of the standard model. I don't need to have a comprehensive understanding of the maths underpinning it all, but it's quite difficult to find any undergraduate level reading on the subject. I'm currently...
  43. M

    Neutrino Minimal Standard Model

    Marcus suggested that the nuMSM deserves its own thread and I agree. The nuMSM is the context in which the Shaposhnikov-Wetterich prediction of the Higgs mass was made. (PF thread.) A search on "nuMSM" at InspireHEP turns up 29 papers, a lot of them about cosmology. Shaposhnikov in...
  44. Greg Bernhardt

    Particle Symmetry and the Standard Model by Matthew B. Robinson

    Author: Matthew B. Robinson Title: Symmetry and the Standard Model Amazon Link: https://www.amazon.com/dp/1441982663/?tag=pfamazon01-20 Prerequisities: Contents:
  45. marcus

    Conformal Standard Model (Meissner Nicolai) resonance at 325 GeV?

    Don't be fooled by the word "conformal". This is not "AdS/CFT" stuff. The math is not stringy. It is very largely the conventional standard model. They've found a way to extend it's applicability and make more radical changes unnecessary. Furthermore it's testable. Here's what Meissner and...
  46. naima

    Is Hestenes massless electron beyond standard model?

    Hi all I just read Hestenes paper He has a massless electron which rotates about a fixed point at the speed of light . (look at eqns 8 9 10 and fig 1) I wonder if this is in the standard model or beyond? What is the lagragian of this "zitter" model?
  47. T

    Standard Model Mathematical Representation

    Hello, everyone. I understand the Standard Model and all of its quarks, leptons and bosons, but could someone show me the equation and simply explain it? I haven't been able to find it or an explanation of how it relates to the graphical representation of the Standard Model. Thanks in advance!
  48. R

    Standard Model Particles: 6 Quarks & 5 Bosons

    Can someone give me the names of all the particles that the standard model refers too remember the first 18... 6 quarks (up- down,top-botoom,nice-paradox) x 3 colors = 18 and i also remeber the mpozons (photon,gluion,higgs,w and z ) :confused: thank you ____________________ antonis...
  49. W

    New Model Beynod the Standard Model Formulation

    Hi; I'm working on a new model beynod the standard model one of MSSM with B-L symmetry I'm trying to install CompHep (Event Generator) on Linux OS (Fedora 17) but always i get the same error gcc -o bin/tab_view.exe src/plot/view_tab.o -lnum -lserv...
  50. M

    Chamseddine/Connes new paper on noncommutative geometry standard model

    What do you make of this recent paper of Chamseddine and Connes? Resilience of the Spectral Standard Model The version of the Standard Model based on a product of the spacetime manifold with a finite noncommutative space had previously predicted a Higgs mass of 170 GeV. Supposedly this paper...
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