Questions tagged [partons]
A parton is a gluon, quark or antiquark in the eponymous model of scattering involving hadrons. In the hadron's infinite-momentum frame, incoming particles will be scattered instantaneously and incoherently, reducing the problem to a simple kernel convolved with parton distributions, at a particular physical scale (as probed by the inverse of the momentum transfer).
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Spin-charge separation and Spin-Statistics relations
Usually, we associate the half-integer spin to fermion, and the integer spin to boson. And there are constraints like the Spin-Statistics relations.
However, in Spin–charge separation or the parton-...
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Textbook for parton distributions?
Are there any textbooks, or good pedagogical review articles, on the subject of parton distributions? I'm looking for such sources that cover all the standard topics, such as:
Generalized parton ...
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Is the starting distribution in the solution of DGLAP IR-bare?
On p.27 of this paper by John Collins, he says that when defining PDFs in terms of partonic number operators, one acquires an IR-divergent bare PDF (eq. 52). The residue of the IR-divergent term is ...
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Polarized structure functions and Bjorken sum rule
I'm trying to understand what the Bjorken sum rule and the polarized structure functions entering it are. I will use equation (2.3) here as a reference for asking the question.
In Peskin, I've only ...
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Parton distribution function in terms of Fock space kets
To my understanding, I can (at least, formally) express the (unnormalized) PDF for a certain constituent of a composite state as
$$
f(x)=f\left(\dfrac{k}{K}\right)=\sum_j m_j^{(k)}|\langle\psi_j^{(k)}|...
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Bjorken Scaling and the Parton Model
It is often said that Bjorken scaling of the deep inelastic structure functions
\begin{equation}
\nu W_2(\nu ,Q^2)\rightarrow F(x)
\end{equation}
(where $Q^2$ is the virtuality of the photon, $\nu=\...
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What are the differences between FFN, VFN, GMVFN and ZMVFN PDF schemes in QCD?
What are the differences between the fixed flavour number (FFN), variable flavour number (VFN), general-mass variable flavour number (GMVFN) and zero-mass variable flavour number (ZMVFN) schemes for ...
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How to define the parton distribution function of the antiquark?
So I can define the quark distribution function within a hadron as
$$
f_{\psi/h}(x)=\frac{1}{2}\int\frac{dz^-}{2\pi}e^{ixP^+z^-}
\langle h(p)|\bar{\psi}(0)\gamma^+\psi(z^-)|h(p)\rangle|_{z^2=0}
$$
...
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Why do parton distribution functions not depend on the total momentum of the composite state?
When defining such quantity as the elastic form factor, I kinda understand why it turns out to be independent of the momentum of the charged particle, and only dependent on the momentum of the photon ...
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Derivation of the Equivalent Photon Approximation in Peskin and Schroeder
I am trying to reproduce the equivalent photon approximation as discussed in chapter 17.5 in Peskin and Schroeder but cannot justify equation (17.93).
The process we are considering is the scattering ...
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Paper showing evidence for Callan-Gross Relation
I am getting ready for a presentation and want to show a plot showing experimental evidence for the Callan-Gross relation. Are there any papers plotting this beyond 1970 across different $Q^2$ or ...
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How to derive quark-antiquark parton distribution relation?
This is kind of similar to this post here How to define the parton distribution function of the antiquark? with no response.
I basically want to derive the following; $f_q(x) = -f_{\bar{q}}(-x)$ where
...
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What are extrinsic and intrinsic flavour production?
In terms of Feynman diagrams, what are extrinsic and intrinsic flavour production?
See for example this paper this paper (p.2).
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OPE leading twist = collinear factorisation?
The operator product expansion systematically expands QFT interactions in terms of a sum of local operators.
Is the leading twist of this expansion identifiable with collinear factorisation and, if so,...
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How are the structure functions in Deep inelastic scattering measured?
I've been reading lots of different textbooks on the parton model and deep inelastic scattering and the discovery of quarks, and most of the time whenever I see a plot, it's about the measurement of ...
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