Questions tagged [hadron-dynamics]
The hadron-dynamics tag has no usage guidance.
42
questions
1
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0answers
48 views
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):
$$\beta=\beta'=0.813(9)$$
$$\nu_\perp=0.584(5)...
0
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0answers
17 views
Where/How can I find the wavefunctions of Excited Baryons/Nucleons
For example: the $P11(1440)$ resonance and the $S11(1535)$ resonance each have a total angular momentum $J = \frac{1}{2}$. How would I go about finding the Spin-Flavor wavefunctions of these and many ...
3
votes
2answers
68 views
How do we decide the proton wave function?
The fully symmetric spin-up proton spin-flavour wave function in the constituent quark model is usually presented as follows:
$$\begin{align}
\frac{1}{\sqrt{18}} ~ (
&2 |u\uparrow ~ u\uparrow ~ d\...
0
votes
0answers
23 views
Resources on Physical Baryon States as mixings of multiplet states
I've been told, and have seen in papers (search for "mixing") that baryon resonances are not plucked from pure group theoretic multiplets, but are most often found to be mixings of states in different ...
1
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0answers
96 views
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://...
2
votes
0answers
21 views
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 ...
0
votes
0answers
20 views
Direction of chiral symmetry breaking
What happens if one breaks the SU(2) chiral symmetry in a non-real direction(a direction apart from the one that the small masses of hadron's constituents(quarks) dictate). Or equivalently We know ...
3
votes
1answer
60 views
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. ...
0
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0answers
36 views
Why are mesons only made of a quark-antiquark pair? [duplicate]
Why can't we have a meson made of two quarks, why does there have to be the antiquark too?
2
votes
2answers
170 views
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)...
0
votes
1answer
24 views
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 $...
0
votes
1answer
35 views
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?
4
votes
1answer
177 views
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 ...
2
votes
0answers
72 views
What is $\gamma$$\rho$ mixing?
In a previous question, I asked about the apparent universality behaviour in hadron elastic scattering. I was particularly shocked to see that even $\gamma p$ showed that universal behaviour with ...
2
votes
1answer
72 views
Do Reggeons-Pomerons-Odderons offer an Universal picture of hadron interactions?
As far as I know, the total cross-sections of the following hadron interactions are well described by a single Reggeon trajectory and a single Pomeron (soft Pomeron) trajectory. It seems to work for ...
2
votes
0answers
48 views
Why are the elastic and total cross-section of $pp$ collisions increasing as the C.O.M. energy grows?
Well, that's about it. I don't find any reasonable explanation for this fact. Are they transversally expanding as the energy increases? Please, remember that strong interactions are short ranged and ...
3
votes
0answers
91 views
Use of Cutkosky rule, the Optical Theorem and Regge trajectories in pp scattering total cross-section calculation
Cutkosky rule states that:
$$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)$$
putting $a=b=p$ in Cutkosky rule we deduce the ...
7
votes
1answer
114 views
In less technical language, what exactly is a “gravitational form factor”?
The term "gravitational form factor" is a term I don't recall ever seeing before the year 2018 (about three decades after I started reading physics papers).
I have read several recent papers about ...
2
votes
1answer
244 views
$pp$ and $p\bar p$ scattering energy scaling exponents and 3d directed percolation model critical exponents similarity/equality, why?
$pp$ and $p\bar p$ scattering can be approximately described (in the Regge limit, that is, when $s \gg m \gt |t|$) by the exchange of Reggeons defined by the following Regge trajectory (low $s$):
$$\...
3
votes
2answers
115 views
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 ($\...
1
vote
1answer
112 views
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?
1
vote
0answers
26 views
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 ...
1
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0answers
78 views
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 ...
1
vote
0answers
58 views
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 ...
1
vote
1answer
477 views
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....
0
votes
2answers
312 views
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 ...
4
votes
2answers
452 views
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 ...
1
vote
2answers
731 views
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?
0
votes
1answer
806 views
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?
7
votes
2answers
992 views
Why do quarks tend to bond in groups of three?
Why do quarks tend to bond in groups of three?
I understand why they might in bond in groups of three to create a net charge of zero (i.e. neutrons), but I don't understand why they form protons and ...
3
votes
1answer
340 views
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.
...
5
votes
1answer
184 views
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 ...
5
votes
1answer
126 views
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. ...
7
votes
2answers
143 views
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
$$\left\langle0|j^{\mu5a}(x)|\pi^b(q)\right\rangle=-if_\pi \delta^{ab} q^\mu e^{-iqx}$$
...
0
votes
2answers
354 views
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?
0
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0answers
44 views
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?]
8
votes
2answers
611 views
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?
2
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0answers
147 views
How to describe hadron-hadron strong interactions from QCD?
I'm trying to set up the problem of deriving the thermodynamics of hadronic matter. I know how to proceed in the case of an effective description such as mean field (Walecka/linear sigma model) but I'...
11
votes
1answer
533 views
Chiral perturbation theory: what is the Quark Condensate? why expand in $U$ rather than Goldstone fields?
I'm studying Chiral Perturbation Theory ($\chi PT$) from Scherer's Introduction to Chiral Perturbation Theory.
What I am currently having some trouble understanding are two things:
The quark ...
38
votes
8answers
19k views
What are the strings in string theory made of?
This is a follow-up to an intriguing question last year about tension in string theory.
What are the strings in string theory composed of?
I am serious. Strings made of matter are complex objects ...
10
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2answers
609 views
Nuclear physics from perturbative QFT
Is there a renormalizable QFT that can produce a reasonably accurate description of nuclear physics in perturbation theory? Obviously the Standard Model cannot since QCD is strongly coupled at nuclear ...
23
votes
5answers
1k views
How do we know that the nucleus isn't a quark-gluon plasma?
The standard picture of the nucleus of atom is that is several distinct nucleons, which themselves are composed of quarks. However, it seems to me like a much simpler picture is that the nucleus is ...
