Questions tagged [beyond-the-standard-model]
Use this tag for questions beyond the standard laws of physics (General Relativity and the Standard Model) if a more specific tag, like "string-theory", "loop-quantum-gravity", "supersymmetry", etc. do not apply.
592
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Theory of opposite interaction of negative masses [closed]
Normally, in the standard model, the more a particle interacts with the Higgs field the more mass it has and slows its speed. Light for example has a mass of 0 because it does not interact with the ...
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Why can't a photon pair produce to an electron anti-muon pair? [closed]
From my understanding, within the context of the Standard Model, charged lepton flavor conservation is an accidental symmetry due to some renormalization condition. How does this work in the case of ...
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Does the standard model predict $\alpha_G^{-1}\approx c_5$ for $m_{proton}$? [closed]
Given $$\alpha_G^{-1} = \frac{m_{planck}^2}{m_{particle\ of\ interest}^2}$$
$$particle\ of\ interest = proton$$
$$c_5 = fifth\ Catalan\ Mersenne\ prime = 2^{(2^{(2^{(2^2-1)}-1)}-1)}-1$$
Does the ...
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What is Effective Field Theory and how is it different from renormalization? [closed]
How is Effective Field Theory different from renormalization? Explained in an intuitive way.
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Is there a clean mathematical way to deduce grand unification from string theory?
The question says it all. Simply stated:
Can one prove grand unification from string theory?
What is the argument chain of such a proof?
The textbooks I read so far only appear to give hand-waving
...
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Distinction between majorana neutrinos and sterile neutrinos
I am a bit confused about Majorana neutrinos. A generic Dirac spinor can be written in terms of his left and right-chiral components as
$$
\psi = \begin{pmatrix} \psi_L \\ \psi_R \end{pmatrix}
$$
A ...
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How can simple classicall things be described with string theory?
It is of course overkill to use string theory for this, but I am still interested in how, for example, the trajectory of a horizontal throw of a mass point could be derived from string theory, after ...
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Which statistical methods are better than basic random scans for studying and exploring the parameter space of extensions of the standard model?
Given a lagrangian of a new model beyond the standard model, and given a set of constraints, say the oblique parameters for instance and the decay of the higgs boson and some signal strengths and ...
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Help with predicted Pati-Salam model Gauge bosons
The Pati-Salam model is a Grand Unification Theory. However, unlike other ones, it does not propose a unified force and just explains the quirky-ness of the standard model.
It includes a fourth color ...
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Where does the motivation for discovering a 5th force come from? Has there been any evidence found yet? [duplicate]
Electromagnetism, nuclear strong, nuclear weak, and the weird notably weaker force of gravity. Now a force is something fundamental to reality, gravity described as the bending of spacetime causing ...
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Degrees of freedom in the early universe with MSSM?
As nicely summarized on P4 in On effective degrees of freedom in the early universe here; at high temperatures where all the particles of the Standard Model are present, we have 28 bosonic and 90 ...
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Toolkit to generate the most general gauge invariant Lagrangian for a given particle content
I am currently working on a BSM model for unification where I am adding scalars for unification. I add many scalars, so finding the most general gauge invariant lagrangian is becoming difficult. Is ...
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1
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Does NFW profile work for any galaxy?
We use Navarro–Frenk–White (NFW) to calculate Dark Matter (DM) density. Can we use it for DM halo in any galaxy or is it used only for Milky Way (MW)?
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Standard model and gravity gauge theory
I will briefly explain my understanding on the subject.
In the following explanation i refer to the Poincarè group meaning the group:
$$\mathcal{P}_{1,3} = \mathbb{R}^{1,3} \rtimes Spin^+(1,3)$$
The ...
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How can strings be more fundamental than quantum fields?
I had the feeling that physics has moved on from the idea that spacially bounded objects located in spacetime (such as particles) can be fundamental. Instead, QFT describes everything by quantum ...
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The chirality of the standard model fermions
I read 'The Standard Model Effective Field Theory at Work' by Isidor, Wilsch, and Wyler. In a footnote, they say that, in principle, right-handed neutrinos could be included in the Standard Model by ...
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Slope in interaction strength vs mass for QCD axion
The theory models of QCD axion, i.e. those who solve the strong CP problem, all have a prediction that follows a band with a slope in the space interaction strength vs. axion mass.
(1) What does cause ...
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Integral on phase space
I'd like to integrate the square amplitude in the phase space( in $d^3k/(2\pi)^3 2E_k$ and $d^3k'/(2\pi)^3 2E_k$) where $p$ and $p'$ are the 4-momentum of the input particles, $k$ and $k'$ 4-momentum ...
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Experimental method for measuring electric dipole momentum of electron
Is there any experiment for finding the electric dipole momentum of electron?
Provided that, The Standard Model predicted EDM for leptons including electrons.
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Effective field theory of massive spin-1 and spin-2
I'd like to understand what could be the use of an effective field theory (EFT) of a single massive particle of spin 1 or 2, or simple modification of these (see below). By EFT, I mean the most ...
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Feynman diagram: Two-way arrow in the fermion propagator line?
I have encountered some diagrams (like the example below) where two lines coming out of a single vertex (in this context, right-handed neutrino $N^c$) have opposite direction. In a usual diagram, a ...
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Why are there no diccussions of hypercharge conservation or Dirac hypercharge monopoles?
The Maxwell equations can be derived from an equation for a spin 1 field with $U(1)$ symmetry. From this field equation is possible to postulate Dirac monopoles by simply roting the real and complex ...
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Doublet-triplet splitting in GUT: how can the "color triplet" have mass?
I'm hopelessly perplexed about the $SU(5)$ doublet-triplet splitting.
I read that the color triplet part of the Higgs quintuplet needs to have extremely high mass compared to the "electroweak&...
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Is $SU(N)$ with $N>5$ ruled out as a GUT?
Reading the "mainstream" sources, the candidates for GUT gauge groups are $SU(5)$, $SO(10)$ and $E_6$
Yet I understand for ranks 5 and 6, $SU(6)$ and $SU(7)$ also have complex ...
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Experimental Consequences of $ZZZ$ Vertex
The gauge boson self-interactions are limited to a relatively small number of possible diagrams in the Standard Model, so in BSM models it is quite common to introduce interactions like a triple ...
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Lifetime of a WIMP [duplicate]
I have been watching videos of WIMP's and have a simple question..
The larger the particles, the shorter their lifetime. A top quark is so massive that it cannot form a "stable" bond with ...
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How do the different Neutrino masses come about?
The determination of the Neutrino mass can be roughly divided in three strategies:
The neutrino mass from cosmological observations:
$$m_\nu = \sum_{i} m_i $$
The neutrino mass from the neutrinoless ...
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1
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Are there enough parameters in standard model to falsify SUSY?
I know that the search for Higgs would be quite pointless if there was no estimation of its mass.
Namely the perturbative violation of unitatity, gave us an upper bound on its mass.Unitarity ...
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Is a QFT always an EFT coming from something deeper?
(I have already read this post but my question is different)
Reading Ch. 12 of Weinberg's Quantum Field Theory Vol. 1, he states that all realistic (interacting) QFTs are now believed to be EFT of ...
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Minimal supersymmetric Standard Model Supersymmetry Breaking
I'm working through Srednicki's QFT book.
I'm at Chapter 96 where he covers the Minimal Supersymmetric Standard Model.
I understand that supersymmetry is not an exact symmetry and I understand that ...
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Is the Higgs VEV unnatural?
Is there some way to argue that the Higgs VEV is unnatural, without even bringing up the Higgs boson mass? For example, can one show that the Higgs vev receives large corrections from new physics? The ...
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Conceptual dobuts about EFTs and the decoupling of heavy fields
I've tried to synthetize some of my misconceptions in the following statements. I just like to know which of them are true and get some intution about them.
EFTs exist only if heavy fields decouple (...
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Why was the Higgs boson included in the standard model, but not supersymmetry?
This is a soft question so may not be suitable for this site.
The LHC famously discovered the Higgs boson several years ago, but also seems to have ruled out several hoped for versions of ...
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CalcHEP and FeynCalc giving different amplitudes--spin averaging?
I've done a simple amplitude calculation involving neutrinos and fermions scattering or annihilating through a BSM gauge boson. I'm checking with FeynCalc and CalcHEP, but the two are giving ...
user367500
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Jarlskog Invariant
Jarlskog Invariant is directly proportional to CP violation. I want to know why it's called "an invariant". What is the nomenclature of the Jarlskog Invariant?
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How did this generalized NJL model from 1993 predict Higgs boson and top quark masses?
Since the Higgs boson was found in 2012, at a mass around 125 GeV, it has often been remarked that this is curiously close to "criticality" or "metastability" or a false vacuum, if ...
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Is there an explanation for why electric charge, or hypercharge, are rational multiples of each other? [duplicate]
Electromagnetic charges are obviously quantized - I suppose the lowest charge being the $d$ charge of $e/3$. Every other charged particle has a multiple of that charge (actually all stable free ...
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Would observed limit on resonant double Higgs production the same if the scenario considered is spin $0$ scalar or spin $0$ radion particle?
At LHC, some analyses search for resonant HH production, from an unknown particle labelled $X$. They typically make the limit on cross-section of resonant HH production as a function of the spin of ...
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1
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Holographic self-energy for a scalar field in a slice of AdS
I am confused about a key step in Gherghetta's "TASI Lectures on a Holographic View of Beyond the Standard Model Physics" in the derivation of the holographic self-energy in the strongly ...
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1
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Caveats in realizing the exact Standard Model from String Theory
String theory admits a vast number of vacuum solutions, which I gather come from the all the ways of compactifying the geometry of spacetime down to 3+1 dimensions using Calabi-Yau manifolds. I have ...
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Lagrangian with negative mass
I was reading a paper https://arxiv.org/abs/1707.03094 considering the SM extension with $SU(2)$ singlet and doublet fermions. After EWSB, the mass eigenstates are the linear combinations of gauge ...
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Could a fourth family of quarks and leptons account for dark matter?
In the early universe, could a family of quarks and leptons have formed an electrically neutral particle that is dark matter?
user361671
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Finite quotient of standard model group [closed]
In chapter three, p. 31, of this paper (https://arxiv.org/abs/0904.1556) Baez and Huerta show that the standard model's structure group contains, in a sense, superfluous parts.
They show that one can ...
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Additional fundamental forces induced by (unknown or not) massless fermions?
Just thinking about one stupid question: what if there are some massless fermions we don't have detected by some reason and they have interactions (related or not with the weak force and the Fermi ...
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Majorana mass matrix seesaw and renormalizable interactions
Sometimes the general seesaw matrix:
$$\begin{pmatrix} M_L & M_1\\ M_2 & M_R \end{pmatrix}$$
and its just said that in order to get renormalizable interactions one must impose the condition $...
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Some questions about Peccei-Quinn-Weinberg-Wilczek (PQWW) model
In PQWW model,we have two Higgs doublet($\phi_1$,$\phi_2$),and the Yukawa interaction of quarks is:
\begin{equation}
\mathcal{L}_{Y}^q=-f_{i j}^{(u)} \bar{q}_{L j} \phi_{2} u_{R i}-f_{i j}^{(u)} \phi_{...
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1
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Why is gluon massless from GUT point of view?
For not violating the gauge invarinace, of course, the gluon is massless. In respect of Spontaneous Symmetry breaking(SSB), however, I wonder why the gluon is massless, compared the $W^+$, $W^-$, $Z$ ...
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1
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About Majorana neutrinos and chirality
If neutrinos are Majorana particles it is possible that neutrinoless double decay happens, with a diagram like this one:
However it seems to me that this diagram requires the Majorana neutrino to ...
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0
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76
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Mass matrix for inverse seesaw mechanism
I am having trouble in diagonalizing analytically the mass matrix associated to the inverse seesaw mechanism with lagrangian:
$L= -y_1\bar{L}\tilde{H}N_{R_1} - -y_2\bar{L}\tilde{H}N_{R_2} + N_{R_1}^...
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$W$ coupling to excited quarks
Can a $W$ couple to both left-handed and right-handed excited quarks? I think this paper says that is true of the $W’$ (https://doi.org/10.1016/j.physletb.2011.03.066).
And I think this article says ...
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