EA propagation: observables

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List of interesting observables

This is a working draft of prioritized interesting observables. As more people will be able to commit time to this project we will be able to move observable from our reserve to active duty.

You are welcome to modify and improve this list, which might as well serve as backbone for our future contributions to JLab and INT white papers.

Please, stick your name where you think you can make a contribution!

High Priority

These we are actively studying. Click on any title to access the dedicated wiki page.

  • Light quarks [ Accardi, Daniel, Dupre, Majumder, Mineeva]
    • π± and K±
      • Attenuation and pT-broadening with multi-dim binning
      • Verify that RM->1 at large ν as indicated by EMC
    • π0 vs. η vs. ηc (vs. ω) mesons (energy loss vs prehadron absorption)
    • K0 vs. φ, ...
    • pT-broadening:
      • vs. Q2 - one of the most intriguing features of HERMES data
      • vs. z - for precision tests of theory models
  • Heavy flavors [ Accardi, Dupre, Majumder ]
    • B vs D mesons (heavy flavor puzzle)
      • similar to π0 vs. η
      • check also RM at large ν vs light flavors
    • how to separate:
      • radiative en. loss
      • collisional en. loss
      • "prehadronic" en. loss
    • J/ψ and charmonium (ψ', χc...) attenuation
      • Test of attenuation mechanisms, e.g., absorption with a given cross-section vs. coherent c-cbar scattering by Qiu-Vary-Zhang
  • Baryons
    • origin of proton "anomaly": p, pbar, Λ Λbar, ...
    • HT production mechanism a la Brodski & C.
  • Cronin effect at large pT
    • start with π± and K± and (anti)p
      • what is the maximum measaurable pT?
    • use cuts in the fractional momentum x to test the size of intial state nuclear modifications
    • test of fragmentation vs. recombination -- no recombination expected in e+A, hence Cronin for mesons~baryons
  • Jets [ Accardi, Lamont, Ploskon, Avakian ]
    • jet rates as a function of cone radius -- induced gluon radiation will broaden the jet
    • interplay of semi-inclusive hadron pT-broadening and jet shapes through value of qhat
    • compare to jets at RHIC
    • 2+1 jets as measure of nuclear gluons
      • check accessible x ranges at eRHIC, MEIC, ELIC [Lamont]
      • sensitivity to PDF after nuclear effects are subtracted with a PPF Monte-Carlo
  • Photons [ Majumder ?, Vitev ?]
    • soft photons: brehmstralhung, test of multiple scattering dynamics
    • hard (prompt) photons: analog of γ+jet in A+A, but much cleaner
  • HBT correlations [ Gilfoyle ]
    • study the nuclear dependence of low-energy hadrons source, i.e., the color string in Lund model terms.
  • Grey tracks (Neutrons in target fragmentation region)
    • for centrality determination [ Gallmeister ]
    • as tests of parton propagation? (see Ciofi degli Atti & Kopeliovich)
    • correlations with leading hadrons ? [ Strikman ?? ]
      • e.g., correlation with leading hadron's z, should test en.loss (decrase) vs absorption (increase)

... to be continued ...


These require some more thought:

  • Nuclear TMDs [ Avakian ]
    • Observable effects due to modification of kT-dependence of nuclear TMDs including f1
    • Multiplicity ratios
    • Spin and azimuthal asymmetries

Ineteresting observables, but so far we lack manpower to explore them:

  • hadron-hadron correlations
    • z correlations (a la HERMES)
    • ΔΦ correlations (back-to-back respect to the virtual photon axis)
  • Test of factorization of FFs
    • large Q2 leverage, can test nuclear FF factorization assumed by Sassot, Strattman, Zurita.

... to be continued ...

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