Early Science Program for Exclusive/Diffraction/Tagging WG

Raphael Dupre and Kong Tu

ePIC Collaboration Meeting

Jan 22, 2025

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Reminder: overview of the program

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Physics interests in the phase-I EIC

(exclusive/diffraction/tagging WP)

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Phase I EIC: Year 1-2 (Medium and light ion)

Exclusive PWG proposals/highlights:

• [NAS and WP physics] Double ratio of diffractive over total DIS (Zr,Cu to proton). Medium size nuclei and relatively high energy give us the first look for saturation signatures.
• Luminosity requirement: Low
• Special/specific detector: No
• Polarization needed: No
• [NAS and WP physics] Medium size nuclei gluon spatial distribution via Vector Meson production.
• Luminosity requirement: Moderate (depending on rho, phi, or J/Psi)
• Special/specific detector: FF detectors need to veto.
• Polarization needed: No
• Deuteron DIS with spectator tagging: free neutron structure (through DIS & DVCS), Short-Range Correlation with gluon modification, etc.
• Luminosity requirement: Low (for neutron PDF), moderate (for neutron GPD), high (for high momentum studies)
• Special/specific detector: OMD is necessary to detect breakup protons, ZDC is needed for neutrons.
• Polarization needed: No, yes for the DVCS

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Phase I EIC: Year 3-4 (proton target)

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Exclusive PWG proposals/highlights:

• [NAS and WP physics] DVCS on proton with polarized target: 3D structure of proton
• Luminosity requirement: moderate to high
• Special/specific detector: Roman Pot
• Polarization needed: yes, ideally of both beams.
• [NAS and WP physics] Exclusive jets (dijets) and Upsilon program: orbital angular momentum and mass origin of the proton.
• Luminosity requirement: moderate to high
• Special/specific detector: all
• Polarization needed: some yes, some no.
• DEMP, pion/kaon SF (pion+neutron, K+lambda),
• Luminosity requirement: high
• Special/specific detector: all
• Polarization needed: No.

*Proton measurement for diffractive to total DIS cross section - the denominator of the double ratio in the previous slide.

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Phase I EIC: Year 5-7 (Heavy ion, He3, proton)

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Exclusive PWG proposals/highlights:

• Coherent and incoherent physics with He3 target: DVCS, VM, inclusive diffraction with tagging.
• Luminosity requirement: moderate to high
• Special/specific detector: FF detectors
• Polarization needed: beam-asymmetry yes, cross section no.
• [NAS and WP physics] Double ratio of diffractive over total DIS for saturation signatures.
• Luminosity requirement: Low
• Special/specific detector: No
• Polarization needed: No

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Our efforts to stimulate the early science

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• We invited three theorists to give talks to enhance theory-experiment collaboration and kick off early science studies:
• Search for Odderon at the EIC (Sanjin Benic)
• Deuteron physics with tagging (Christian Weiss)
• Inclusive diffraction in Sartre (Tobias Toll)

Early Science - Inclusive diffraction

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https://indico.bnl.gov/event/25025/

Early Science - Inclusive diffraction

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https://indico.bnl.gov/event/25025/

Early Science - Deuteron

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https://indico.bnl.gov/event/24954/

Early Science - Deuteron

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https://indico.bnl.gov/event/24954/

Early Science - Odderon

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https://indico.bnl.gov/event/24952/

Early (maybe) “Advanced” Science - Odderon

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https://indico.bnl.gov/event/24952/

Its equally important to study something “Phase-I” isn’t enough.

More specifics: planning and working together

Year 1 (Ru/Cu):

• Inclusive diffraction on Ru/Cu (requires a new version/feature from Sartre and work with model developers).
• Exclusive VM on Ru/Cu (generators are ready, eSTARLight and BeAGLE).

Year 2 (D2):

• Deuteron: i) free neutron structure, ii) EMC effect, and iii) diffraction on nucleon with spectator tagging
• DEMP on proton or neutron with spectator tagging (model development is needed!)

Year 4 (Au?):

• Exclusive VM and inclusive diffraction, similar to Year 1 on the readiness.

Year 5 (He3):

• Spin asymmetry with He3: extraction of alpha_s, and neutron spin structure.

Year 3-7 (proton):

• DVMP Jpsi (generators are all ready, analysis are there. Need to rerun the specific settings)
• DVCS photon (generators are all ready, analysis are there. Need to rerun the specific settings)

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More specifics: planning and working together

Year 1 (Ru/Cu):

• Inclusive diffraction on Ru/Cu (requires a new version/feature from Sartre and work with model developers).
• Exclusive VM on Ru/Cu (generators are ready, eSTARLight and BeAGLE).

Year 2 (D2):

• Deuteron: i) free neutron structure, ii) EMC effect, and iii) diffraction on nucleon with spectator tagging
• DEMP on proton or neutron with spectator tagging. Model development is needed (model development is needed!)

Year 4 (Au?):

• Exclusive VM and inclusive diffraction, similar to Year 1 on the readiness.

Year 5 (He3):

• Spin asymmetry with He3: extraction of alpha_s, and neutron spin structure.

Year 3-7 (proton):

• DVMP Jpsi (generators are all ready, analysis are there. Need to rerun the specific settings)
• DVCS photon (generators are all ready, analysis are there. Need to rerun the specific settings)

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Talk by Win on Thursday morning exclusive WP session

Updates and supports needed

• Preliminary run plan
• Year one: e + Cu or e + Ru 10x115 GeV/n
• Year two: e + deuteron 10x130 GeV/n
• Year three: e + p 10x130 GeV
• Year four: e + p 10x250 GeV
• Year five: e + He3 10x166 GeV/n�
• Needs from the accelerator (FF region)
• General beam parameters at the IP for the correct afterburner application (e.g. emittances).
• Optics configurations for the various beam energies and species in the FF hadron region.
• Cannot do credible reconstruction without the correct magnet settings to tune the matrices.
• B0 magnetic field is fixed, while the other 6 magnets change – cannot simply scale with energy, otherwise the B0 performance w.r.t. the other detectors is artificially impacted (already a problem now for our ion beam settings).�
• Needs from the detector working group (dependent on the above information)
• RP and OMD reconstruction matrices for all beam energy configurations.
• Beta functions at RP location to determine low-pT acceptance (10sigma cut).

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Input by Alex Jentsch

A general approach

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Analyzers express interests in some topics in Phase-I science

Conveners help evaluate the readiness:

1. Generator
2. Configuration (ePIC)
3. Simulation

1. Analyzers work with generator developer to fine-tune the model (beam energy, species, MC expectation)

2. Test small sample in ePIC (afterburner, record time and disk space requirement, etc.).

3. Follow guidelines from production team and submit request for simulation to Conveners and production team.

Analyze results and update in WG.

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Document the results (benchmarks)

A general approach

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Analyzers express interests in some topics in Phase-I science

Conveners help evaluate the readiness:

• Generator
• Configuration (ePIC)
• Simulation

1. Analyzers work with generator developer to fine-tune the model (beam energy, species, MC expectation)

2. Test small sample in ePIC (afterburner, record time and disk space requirement, etc.).

3. Follow guidelines from production team and submit request for simulation to Conveners and production team.

Analyze results and update in WG.

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Document the results (benchmarks)

Analysis Coordination

Set standards

PWG conveners

Check analysis quality

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Support & coordination needed:

• Theory or MC support (Analyzer’s responsibility and conveners may help)

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• Machine, detector, or ePIC framework support (speedy response from detector experts)

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• Simulation production support (speedy process after fulfilling submission requirements)

Summary

• Phase-I science at the EIC is instrumental to our group. We have a diverse interests in the early science program.

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• Topics/analyses outnumber the analyzers (we need more person-power from this BIG collaboration.)
• Supports and coordinations from AC, SC, and management are crucial. This can’t be done single-handedly. Communication is the key.
• Suggestions, ideas, helps are all welcome.

Exclusive WG meeting is biweekly, Monday, 12pm EST (next one is Feb 10)

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