Standard model Definition and 258 Threads

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...

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...

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

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...

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...

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.

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

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...

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...

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?

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.

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...

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...

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...

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?

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...

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.?

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...

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...

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...

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...

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...

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...

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...

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)...

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...

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...

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...

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?

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...

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...

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...

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...

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

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...

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?

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!

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...

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...

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...

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...

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...

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...

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...

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...

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...

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

what is the the easiest way to learn standard model theory ?

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