Questions tagged [hadron-dynamics]

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Non-relativistic quark model, baryon masses and potential

Is there a simple non-relativistic quark model, based on which baryon masses, especially for the nucleon and the Delta resonance can be calculated? What is a reasonable non-relativistic potential? Is ...
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What are hadron parity partners?

I am studying Lattice QCD and there are many papers mentioning "Parity partners". What does this term mean?
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How to calculate the branching fraction of hadrons? Or good resources on chiral perturbation theory

I am wondering how I could calculate branching ratios (or any effective diagram) for various hadrons. In particular I am interested in a rare pion decay via a virtual photon:$\pi^0\to \gamma \gamma^* \...
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Is hadronic calorimetry dependent on pion production?

I'm new to this area and currently reviewing literature before making simulations with a toy model for calorimetry. While reading some texts about hadronic calorimeters, I have the impression that the ...
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Form Factors in Particle Physics

I am having trouble understanding how people parameterise hadronic matrix elements in terms of form factors. For example the decay of a pseudoscalar B to a vector meson: $$ \langle V(k, \eta) | \bar q ...
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Is there a differential equation describing the wavefunction of a hadron?

In Newtonian Physics there's a differential equation describing the motion of multiple bodies in orbit around each other. In non relativistic quantum mechanics there's a differential equation ...
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How to draw Feynman diagram of quark decaying to more than three quarks (weak), and tell if it's Cabibbo-allowed/supressed?

I have problems when it comes to drawing Feynman diagrams that involve weak decays creating more than two quarks. So I hope one of you can help me clarify. let's consider the following problem: Will ...
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Should quarks be grouped together in Feynman diagrams?

I have a questions regarding Feynman diagrams when it involves hadrons. I think the easiest way is considering this reactions: 1) $\Lambda_{c}^{+} \rightarrow p+\bar{K}^{0}$ I need to draw the ...
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Evolution of the proton without external interactions

I've been thinking about the possibility of the proton evolving without external interactions and came up with the following problem. Let's say we have an isolated proton and therfore the Lagrangian ...
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Mass difference between two baryons

I have been trying to make sense out of this (unsuccessfully for days). It's an exercise on Particle Physics. Exercise asks to calculate the mass difference between baryons ($cuu$) with \begin{...
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Hadron-Hadron collisions: classification of events

In hadron-hadron collisions, scattering events can be classified into diffractive and non-diffractive events. I don't clearly understand the definition of this two adjectives and I don't understand if ...
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Can a baryon consist of two quarks and an antiquark? Or a pentaquark be made of three quarks and two antiquarks? [duplicate]

I suspect these particles exist, but are extremely short-lived, even compared to other unstable, exotic particles...
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Interference term in hadronic processes

If we consider two hadronic processes with the same final state, example : should one also include an interference term in cross-section despite the different propagators? What would be in cases ...
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Emergence of Dual Resonance model from QCD

This question is about getting to understand better what the Dual Resonance (DR) model actually managed to successfully predict or model from the nuclear interactions, in the context of understanding ...
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Permitted bound states in extended QCD color group $SU(4)$

I'm very much curious about the possible quark combinations to form bound states in $SU(4)$ QCD. We already know Wilson has proven that only colorless combinations can arise in $SU(3)$ of these ...
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Pion+ and proton make kaon+ and another strange particle, X. Why is this the strong interaction?

The answer is the strong nuclear force. After having looked at Feynman diagrams online for similar interactions I figured out an interaction for this one that I have drawn above. Is that correct? I ...
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Can one show that hypernuclei are always unstable?

Normal atomic nuclei are composed of protons and neutrons, where the local interactions stabilize the neutrons that are unstable in isolation. Hypernuclei have one or more strange hadrons beside the ...
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Could the Odderon intercept be equal to $\alpha_\mathbb {O}(0)=0.813$? [closed]

The directed percolation dynamical universality class is characterized by just three independent critical exponents. These exponents are (in a 3d space): $$\beta=\beta'=0.813(9)$$ $$\nu_\perp=0.584(5)...
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How do we decide the proton wave function?

The fully symmetric spin-up proton spin-flavour wave function in the constituent quark model is usually presented as follows: $$\begin{align} \frac{1}{\sqrt{18}} ~ ( &2 |u\uparrow ~ u\uparrow ~ d\...
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How do soft Pomerons become hard?

The exchange of soft Pomerons (and Reggeons) ($\alpha_R(0)=0.55$ and $\alpha_P(0)=1.08$) seem to describe total hadron-hadron cross sections pretty well in the Regge limit. See, for example: https://...
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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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Why Aren't Hadron Masses More Useful In Determining Standard Model Constant Values?

Some of the most exquisitely precise experimental measurements in all of physics are the masses of the various hadrons. Consider these examples: the proton mass is known to eleven significant digits. ...
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If quarks can't be isolated in the first place, how did they become confined in the early universe?

On one hand, we know that quarks cannot exist in isolation. This is because the energy required to dissociate a quark-antiquark pair in a meson (or quarks in a hadron) will create a mesons (or hadrons)...
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Relation of vector and scalar matrix elements for hadronic transitions

Consider a matrix element $$ F_{\mu}(p_{h'}, p_{h}, \dots) = \langle h'(p_{h'})|\bar{q}_{i}\gamma_{\mu}q_{j}|p_{h}\rangle, $$ describing transition of some initial hadron $h$ that contains a quark $...
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Conversion of gluons into hadrons

Why and how does a gluon become a hadron when it leaves a hadron? Is this an analogous process to the way a quark becomes a meson, when it is "forced" out of (let's say) a proton?
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At what stage is it necessary to introduce a field theory in the regeon-pomeron-odderon model of hadron interactions?

I've been reading some papers from G.F. Chew and S. C. Frautschi and they do not even bother to introduce the concept of "Field" when they describe hadron interactions. My impression is that they do ...
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What is $\gamma$$\rho$ mixing?

In a previous question, I asked about the apparent universality behaviour in hadron elastic scattering. I was particularly shocked to see that even $\gamma p$ showed that universal behaviour with ...
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Do Reggeons-Pomerons-Odderons offer an Universal picture of hadron interactions?

As far as I know, the total cross-sections of the following hadron interactions are well described by a single Reggeon trajectory and a single Pomeron (soft Pomeron) trajectory. It seems to work for ...
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Why are the elastic and total cross-section of $pp$ collisions increasing as the C.O.M. energy grows?

Well, that's about it. I don't find any reasonable explanation for this fact. Are they transversally expanding as the energy increases? Please, remember that strong interactions are short ranged and ...
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Use of Cutkosky rule, the Optical Theorem and Regge trajectories in pp scattering total cross-section calculation

Cutkosky rule states that: $$2Im \big(A_{ab}\big)=(2\pi)^4\sum_c \delta\Big(\sum_c p^{\mu}_{c}-\sum_a p^{\mu}_{a}\Big)|A_{cb}|^2\hspace{0.5cm} (1)$$ putting $a=b=p$ in Cutkosky rule we deduce the ...
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In less technical language, what exactly is a "gravitational form factor"?

The term "gravitational form factor" is a term I don't recall ever seeing before the year 2018 (about three decades after I started reading physics papers). I have read several recent papers about ...
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$pp$ and $p\bar p$ scattering energy scaling exponents and 3d directed percolation model critical exponents similarity/equality, why?

$pp$ and $p\bar p$ scattering can be approximately described (in the Regge limit, that is, when $s \gg m \gt |t|$) by the exchange of Reggeons defined by the following Regge trajectory (low $s$): $$\...
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Typical size of QCD bound states

Consider the Hydrogen atom and its quantum mechanical description. The excited states of the electron are at energies $E = -E_0/n^2$ with $E_0 = 13.6 \,$eV. This is a weakly coupled bound state ($\...
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What is the significance of finding quark-antiquark pairs in hadrons?

What is the significance of finding quark-antiquark pairs in hadrons? Does is have any effect, and hypothetically, could you pull the 3 quarks in a hadron apart so they formed 3 mesons?
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vector mesons identified with positive parity

I have seen in some sources (like in https://arxiv.org/abs/1610.06090, page 11, footnote 11 but also in some few more) that vector mesons are assigned with positive parity $(J^P)=1^+$. In Particle ...
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Early hadronic string theory leaving me confused!

I am almost finished watching Leonard Susskind's String Theory lecture series on Youtube, and, while I find it very accessible, there's something seriously self-contradictory about the historical ...
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Can somebody explain how to add hadronic interaction in human phantom example of Geant4? [closed]

I want to include hadronic interaction in human phantom example of Geant4. There is a header file G4HadronicInteraction.hh and a C++ file G4HadronicInteraction.cc and a file named ...
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Why is a Kaon strange?

I've read that because Kaons are produced by the strong interaction and decay by the weak interaction that this makes them strange. However protons and neutrons decay by the weak interaction as well i....
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What is the weak isospin of hadrons?

What are the weak isospins (T3 values) of various hadrons, including the proton, neutron, mesons, hyperons and other hadrons? How is the weak isospin calculated for any hadron? Published sources ...
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Yang-Mills theories, confinement and chiral symmetry breaking

I was thinking about hadrons in general Yang-Mills theories and I have some doubts that I'd like to discuss with you. Suppose that we have a Yang-Mills theory that, like QCD, tend to bind quarks ...
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Is there any stable hadron?

Neutron can decay into proton and I think some hypothesis claim that proton can also undergoes decay into subatomic particles... Is there any hadron that never decays?
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Colorless charge in a baryon

In a baryon there are 3 quarks and in a meson there are one quark + one anti-quark. So color charge is colorless ( a color singlet state ) in a meson. But how is it colorless in a baryon?
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8 votes
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Why do quarks and antiquarks tend to bond in groups in which the number of quarks minus the number of antiquarks is divisible by 3?

Why do quarks and antiquarks tend to bond in groups with quark number a multiple of 3? I understand why they might in bond in groups of three to create a net charge of zero (i.e. neutrons), but I don'...
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Regarding parity conservation in the decay $\omega \to \pi^0 \,\pi^+\, \pi^-$

I'm somewhat confused by this decay. Associated vertex seem to be related to QCD residual terms contributing to the nuclear force, therefore they should manifest conservation of Isospin and Parity. ...
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Can the effective vertex for $\gamma\to3\pi$ be derived directly from the anomaly?

My question is whether the effective vertex for $\gamma\to3\pi$ can be derived directly from the anomaly (given in the first equation below), in analogy with the $\pi^0\to2\gamma$ vertex? As far as I ...
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A pedagogical exposition of the hadron physics?

I am looking for a textbook/lecture notes/etc. on the basics of hadron physics. I wish to understand how to construct the effective Lagrangian for pions and nucleons starting from the QCD Lagrangian. ...
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Where do negative powers of $f_\pi$ in the hadronic amplitudes come from?

According to Peskin and Scrhroeder the pion decay constant $f_\pi$ is defined via the following matrix element $$\left\langle0|j^{\mu5a}(x)|\pi^b(q)\right\rangle=-if_\pi \delta^{ab} q^\mu e^{-iqx}$$ ...
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Quantum hadrodynamics

What is quantum hadrodynamics? Can anybody give a proper explanation? What are the standard books and sources of information that can be found on the internet for better understanding?
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Relativistic non-linear Walecka model

What is meant by a relativistic non-linear Walecka model? What are some various sources to study it? [And why cannot Google show a satisfactory result to such a simple question?]
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Why does the Walecka model not include pions?

The Walecka or $\sigma$/$\omega$-model is an effective theory describing nucleon-nucleon interaction by an exchange of $\sigma$/$\omega$-mesons. Why does it not include interactions by pions?
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