A Universal picture of hadron interactions?

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SUMMARY

The discussion centers on the total cross-sections of various hadron interactions, which are accurately described by a single Reggeon trajectory and a single soft Pomeron trajectory. The specific interactions include K^-p, K^+p, \bar pn, pn, p\bar p, pp, \pi^-p, \pi^+p, and \gamma p, with detailed mathematical expressions provided for each. Participants express confusion regarding the photon-proton interaction in the 1 to 20 GeV range, questioning the role of Reggeon and Pomeron exchanges versus Compton scattering. The conversation highlights the precision of these theoretical models and references key literature, including Gribov's "Theory of Complex Angular Momentum" and Feynman's "Photon Hadron Interactions".

PREREQUISITES
  • Understanding of Regge theory and Pomeron dynamics
  • Familiarity with hadron interactions and cross-section calculations
  • Knowledge of Quantum Chromodynamics (QCD) and vacuum perturbation theory
  • Basic grasp of photon interactions in particle physics
NEXT STEPS
  • Study Gribov's "Theory of Complex Angular Momentum" for insights into Regge theory
  • Explore Feynman's "Photon Hadron Interactions" for foundational concepts
  • Research the role of virtual quark loops in photon propagation
  • Investigate the historical context of Regge theory literature from the late 1960s
USEFUL FOR

Particle physicists, researchers in hadron interactions, and students studying quantum field theory will benefit from this discussion, particularly those interested in the nuances of Reggeon and Pomeron dynamics.

Anashim
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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.
  1. ##K^-p: (11.93s^{0.0808}+25.33s^{-0.4525})mb##
  2. ##K^+p:(11.93s^{0.0808}+7.58s^{-0.4525})mb##
  3. ##\bar pn:(21.70s^{0.0808}+92.71s^{-0.4525})mb##
  4. ##pn:(21.70s^{0.0808}+92.71s^{-0.4525})mb##
  5. ##p\bar p:(21.70s^{0.0808}+98.39s^{-0.4524})mb##
  6. ##pp:(21.70s^{0.0808}+56.08.39s^{-0.4524})mb##
  7. ##\pi^-p:(11.63s^{0.0808}+36.02s^{-0.4525})mb##
  8. ##\pi^+p:(11.63s^{0.0808}+7.58s^{-0.4525})mb##
  9. ##\gamma p:(0.0677s^{0.0808}+0.129s^{-0.4525})mb##
The last expression is hard for me to understand: in the ##1## to ##20 GeV## range the photon and the proton seem to exchange a Reggeon trajectory and a Pomeron trajectory, although I would tend to think that it should be some kind of Compton scattering. I just don't get it, the only charge a photon sees is the EM charge! Could anyone, please, offer a reasonable explanation?Why are these results so unexpectedly accurate? This is a theory I do not particularly like but its results are very precise, specially if you add multiple Pomerons and the Odderon. No other phenomenological model is able to match its results.

These plots can be see in slides number 35 and 36 of the following presentation (from a physicist working at the "KEK Theory Center"):

https://indico2.riken.jp/event/2729/attachments/7480/8729/PomeronRIKEN.pdf
 
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Anashim said:
The last expression is hard for me to understand
Virtual quark loops in the photon propagator?
 
mitchell porter said:
Virtual quark loops in the photon propagator?

Do you mean that renormalization via virtual quark loops makes a real photon behave like a neutral meson? Could you, please, provide some references?
 
Anashim said:
Do you mean that renormalization via virtual quark loops makes a real photon behave like a neutral meson? Could you, please, provide some references?

1970s picture of photon-rho mixing, there is a review by Kurt Gottfried in an early 1970s QED conference hosted at Cornell. It's referenced in Feynman's "Photon Hadron Interactions".
 
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Anashim said:
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.
  1. ##K^-p: (11.93s^{0.0808}+25.33s^{-0.4525})mb##
  2. ##K^+p:(11.93s^{0.0808}+7.58s^{-0.4525})mb##
  3. ##\bar pn:(21.70s^{0.0808}+92.71s^{-0.4525})mb##
  4. ##pn:(21.70s^{0.0808}+92.71s^{-0.4525})mb##
  5. ##p\bar p:(21.70s^{0.0808}+98.39s^{-0.4524})mb##
  6. ##pp:(21.70s^{0.0808}+56.08.39s^{-0.4524})mb##
  7. ##\pi^-p:(11.63s^{0.0808}+36.02s^{-0.4525})mb##
  8. ##\pi^+p:(11.63s^{0.0808}+7.58s^{-0.4525})mb##
  9. ##\gamma p:(0.0677s^{0.0808}+0.129s^{-0.4525})mb##
The last expression is hard for me to understand: in the ##1## to ##20 GeV## range the photon and the proton seem to exchange a Reggeon trajectory and a Pomeron trajectory, although I would tend to think that it should be some kind of Compton scattering. I just don't get it, the only charge a photon sees is the EM charge! Could anyone, please, offer a reasonable explanation?Why are these results so unexpectedly accurate? This is a theory I do not particularly like but its results are very precise, specially if you add multiple Pomerons and the Odderon. No other phenomenological model is able to match its results.

These plots can be see in slides number 35 and 36 of the following presentation (from a physicist working at the "KEK Theory Center"):

https://indico2.riken.jp/event/2729/attachments/7480/8729/PomeronRIKEN.pdf

The question is "why does Regge exchange work". Forget about the photon, the scattering is strong-interaction dominated, and would be the same for two neutrons. The QED part is annoying because it doesn't really have a well-defined cross section, because of log-annoyances due to massless photons, people just ignore the charge effects in these cross sections. There is no quantitative theory which can answer this. The best way to understand it qualitatively is that the vacuum in QCD is perturbed by a proton so that there is a cloud of deformation of the vacuum glue and quark condensates, and the protons exchange bound states which define the vacuum deformation. The best reference is Gribov's book "Theory of Complex Angular Momentum", but you should look at all the Regge literature of the late 60s, because this is not covered well anywhere, including later string books.
 
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Ron Maimon said:
1970s picture of photon-rho mixing, there is a review by Kurt Gottfried in an early 1970s QED conference hosted at Cornell. It's referenced in Feynman's "Photon Hadron Interactions".
Ron Maimon said:
The question is "why does Regge exchange work". Forget about the photon, the scattering is strong-interaction dominated, and would be the same for two neutrons. The QED part is annoying because it doesn't really have a well-defined cross section, because of log-annoyances due to massless photons, people just ignore the charge effects in these cross sections. There is no quantitative theory which can answer this. The best way to understand it qualitatively is that the vacuum in QCD is perturbed by a proton so that there is a cloud of deformation of the vacuum glue and quark condensates, and the protons exchange bound states which define the vacuum deformation. The best reference is Gribov's book "Theory of Complex Angular Momentum", but you should look at all the Regge literature of the late 60s, because this is not covered well anywhere, including later string books.

Ok thank you very much for the info. I will read both books, although I suspect that it's going to take me awhile.
 
Me asking about the ##\gamma p## elastic scattering has anything to do with Ron Maimon being banned? I am not aware of having asked anything unrelated to mainstream physics, but if I have, I would be grateful if anybody could tell me what it is, so that, in the future, I can avoid the topic. Moreover, if I have, I guess it's only fair to ban me, not him.
 
Last edited:
Anashim said:
Me asking about the ##\gamma p## elastic scattering has anything to do with Ron Maimon being banned? I am not aware of having asked anything unrelated to mainstream physics, but if I have, I would be grateful if anybody could tell me what it is, so that, in the future, I can avoid the topic. Moreover, if I have, I guess it's only fair to ban me, not him.
We do not discuss bans, but I can say that this thread has nothing to do with it.
 

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