Questions tagged [physics]
Questions related to the application of Mathematica to problems in physics.
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SixJSymbol not triangular in basis transformation
The basis transformation is given by
$$\left| J^{P}, jd \right\rangle = \sum_ {S} (-1)^{J + L + Sd + Sq}\sqrt {(2 S + 1) (2 jd + 1)}\, \biggl\{\begin {array} {ccc} L & Sq & J \\ S & Sd &...
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TensorD extension pack for the Package-X
Does anyone have a copy of TensorD extension pack for the Package-X?
The Package-X is a Mathematica package for QFT calculations. Unfortunately, it is no longer developed and the official website (...
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Calculate and transfrom the metric to the orthonormal frame
Let's suppose, the line element is like this:
$$ds^2 = -a^2(1+2\psi)d\tau^2 - 2a^2 B_idx^i d\tau + a^2(1-2\phi)(dx^2 + dy^2 + dz^2)$$
I like to get the output of the metric components from it, ...
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2D Projected Stocastic GPE Equation With Vortices
I am trying to solve the Projected Stochastic Gross-Pitaevskii equation with periodic boundary conditions from this paper https://arxiv.org/pdf/1905.05263. This equation can be found in https://...
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Clebsch–Gordan coefficient calculation for L-S basis in system of three particles
I am trying to calculate eq (A3)
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StreamPlot3d for the magnetic field of a loop
I am trying to go beyond StreamPlot in the case of a current loop that produces a magnetic field. My code works for StreamPlot, but does not end when I use the same field expressions with StreamPlot3D....
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Checking the formula for solving the Poisson equation with an integral over all of space
EDIT: According to 2.2.3 Rigorous derivation, if we find the integral $u(x,y) = \int \int G(x,y,m,n)f(m,n) dm dn$ then we obtain a function that satisfies the Poisson equation $\nabla^2u(x,y)=f(x,y)$. ...
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Help me figure out how to solve the gravitational lens equations [migrated]
I want to simulate gravitational lensing. In the article LENSINGGW: a PYTHON package for lensing of gravitational waves there is this fragment [page 3]:
My research: As far as I understand, this is a ...
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97
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Computing eigenvalues and eigenvectors of large matrix and scaling of data
I am trying to plot graphs 1(a1,b1,c1) from https://arxiv.org/pdf/2404.14971 by solving Eq.1. This gives a matrix. For the energy plot, we have to find the lowest 2 eigenvalues and find the difference ...
- 341
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Package for calculating ADM mass for a given asymptotically flat metric tensor
I am asking for Mathematica package, such that for the input of an asymptotically flat Lorentzian metric tensor $g_{\mu\nu}$ it will give the ADM mass of the object that creates the corresponding ...
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127
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Mathematica package for validating effective string theory solution
I am asking for Mathematica package that given an input of:
symmetric matrix $G_{\mu\nu}$, antisymmetric matrix $B_{\mu\nu}$ and a scalar function $\Phi$
will check whether it is a solution to the one-...
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67
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Need help in plotting a graph calculated with ``NIntegrate``
This is my Mathematica code,
...
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1
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107
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How can I combine a selections of video frames into a composite using Mathematica?
I'd like to use Mathematica to be able to turn videos of my students dropping balls into a composit image of selected frames showing the path of the ball. Like a multiple exposure image.
So far, I've ...
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Why is NDSolve ignoring two PDEs out of three ones I am solving?
I am solving the following coupled system of 3 PDEs modelling a 1D membrane coupled to a 1D fluid flow field underneath.
However, on putting them into NDSolveValue (and trying with FEM), it says the &...
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Stabilise equations for motion of Inextensible string subject to spatially non-uniform forces
I would like to simulate the motion of an inextensible membrane in 1D as an inextensible string subject to spatially-dependent body forces. For now, I would like it to be constrained at both ends. I ...
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How to simplify the results of squared amplitude calculations in FeynCalc?
I want to calculate the squared amplitude of the Feynman diagram of double-pion photoproduction using FeynCalc package. Here is the code I created:
...
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Plot of Density of States Using DiracDelta Function [duplicate]
I am trying to plot the density of states $$ N(E)= \frac{1}{N}\Sigma_{k} (\delta{(E - \epsilon_{k}))} $$ where $\epsilon_{k} = -2t*[cos(k_x)+cos(k_y)]$ and $k$ goes from $-\pi$ to $\pi$. For this plot,...
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Need explanation on data[[i]][[1]]
I am trying to train a physics model and then check its profile. For this model, data for physics model is defined with:
...
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2
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141
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How to solve a matrix differential equation $\frac{d X}{dt} = i(X Y- Y^\dagger X)$?
In eq (21) on page-5 of this article, we have matrix
HEP = (\[Omega]/2)*{{-2*I, 1}, {1, 0}};
and I am interested in finding matrix ...
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83
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How to decrease the computation timing while using NIntegrate?
I'm trying to calculate the $A$ and $F$ values by using this code,
...
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Trying to use NIntegrate and my code works intermittently - Throws one error consistently, but only gives me a partial result [closed]
I'm trying to do some calculations/simulations of pulse autocorrelations of non-integer orders and when I try to use NIntegrate it only works intermittently, and when it does work it only gives me a ...
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2
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98
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How to demonstrate the acceleration using spherical coordinates and spherical unit vectors?
I've been trying to use Mathematica to demonstrate using spherical coordinates and unit vectors the acceleration for a particle moving in a sphere. Nevertheless, I'm actually not that skilled in ...
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1
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100
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Components of Faraday tensor
Maybe it's a very basic physics question but I'm confused and not sure if I should ask my question here. From this paper, I have the potential vector
$$ A=A_t d t+A_\phi(d \phi-\omega d t) $$
where
$$ ...
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Implementation of a cavitation model
Problem formulation
Hi,
I'm following this reference and I am trying to reproduce Fig. 19:
The problem concerns an underwater shockwave, which hits the water-surface and produces a cavitation region. ...
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103
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How to effectively substitute variables in xAct?
I am trying to find the gauge field equation by varying the Born-Infeld Action with the help of xact package. I use the following ...
- 2,433
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122
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Graph of an ergoregion
I'm trying to graph the region defined by the following equation (which comes from the $g_{00}$ element of the metric (2.1) in this paper)
$$ g_{00}=-f H+H^{-1} \omega^2 r^2 \sin ^2 \theta $$
which in ...
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1
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142
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Varying Einstein-Hilbert action through xAct gives extra terms
I am trying to find the associated field equation by varying this action:
$$S=\int d^4x \sqrt{-g}(\kappa \mathcal{R}+\Lambda)$$
This should give me the below field equation when I vary above w.r.t the ...
- 2,433
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1
answer
143
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Embedding plot of Minkowski
I am trying to obtain the embedding diagram of Minkowski space. I took the metric:
$$ d s^{2} = - d t^{2} + d r^{2} + r^{2} \left( d \theta^{2} + \sin^{2} \theta d \phi^{2}\right) $$
for $t =$ cte and ...
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How to define the square root of an operator [duplicate]
How can I define the operator $\sqrt{m^2-\frac{\partial^2}{\partial x^2}}$, such that it acts on the function $\psi(x)$ as follows: \begin{eqnarray*}
\sqrt{m^2-\frac{\partial^2}{\partial x^2}}\...
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Peak Appearances in Plot Outputs from Optimization Routines
Dear fellow researchers and Mathematica enthusiasts,
I've been working on a computational physics problem and encountered an interesting issue regarding the appearance of peaks in my plots, which I ...
