BEAGLE - RECENT PROGRESS ON EA SIMULATIONS AT THE EIC - INDICO

EIC

 AGS

BeAGLE
 - Recent progress on eA
 simulations at the EIC

 Kong Tu
 BNL
 07.27.2020 Center for Frontiers
 EIC Jet workshop in Nuclear
 1 Science

What is BeAGLE?
 Benchmark eA Generator for LEptoproduction
• Initiated by E. Aschenauer, M.Baker, JH. Lee, Z. Liang.
• Now with many developers and collaborators…
• Pythia 6 + DPMJet + Fluka - embed an elementary eN
 collision into a nuclear environment,
 https://wiki.bnl.gov/eic/index.php/BeAGLE
• First BeAGLE paper is published on arXiv,
 https://arxiv.org/abs/2005.14706

 EIC Jet workshop 2

Contributors & Collaborators
 What is BeAGLE? W. Chang, A. Jentsch, K. Tu
 Benchmark eA Generator for LEptoproduction
• Initiated by E. Aschenauer, M.Baker, JH. Lee, Z. Liang. + R. Dupré, N. Armesto,
 M.Ehrhart+DPMJET team +
• Now with many developers and collaborators… Fluka team + Pythia team
• Pythia 6 + DPMJet + Fluka - embed an elementary eN
 collision into a nuclear environment, A. Accardi, R. Dupré, M. Erhart,
 https://wiki.bnl.gov/eic/index.php/BeAGLE C. Fogler, C. Hyde, V. Morozov,
 P. Nadel-Turonski, K. Park, J.
• First BeAGLE paper is published on arXiv, Stukes, A. Sy, T. Toll, G. Wei
 https://arxiv.org/abs/2005.14706

 Theory: M. Strikman, C.
 Weiss, R. Venugopalan …

 SRC: D. Higinbotham, P. Nadel-
 Turonski, C. Hyde, O. Hen, T.
 Ullrich, A.Deshpande, V.
 Morozov, B Schmookler, F.
 Hauenstein, A. Schmidt

 EIC Jet workshop 3

Recent progress and effort
• Since summer 2018, BNL has new manpower
 developing/working on BeAGLE.
• EIC Detector R&D - eRD17 is continued to be
 funded for FY20 and trying to renew for FY21
• BeAGLE has been shown to be extremely useful
 for EIC IR designs, forward detectors, ... very active
 and popular for the YR effort.
(Diffractive & Tagging group, Exclusive group, Far forward
detector group)

• In this talk, only focus on a few recent progresses
 to demonstrate BeAGLE’s impact on the EIC.

 EIC Jet workshop 4

Interaction Region - EIC

 ZDC

 Roman pots B1apf dipole
 (inside pipe) Hadron beam
 coming from IP
 Off-Momentum Detectors
 B0pf dipole

 B0 Silicon
 Detector

• Realistic physics simulations are crucial for designing the IR and their detectors.

• For example, the Roman pots, Off-Momentum detector, and B0 in the forward region is now
 being studied based on ep and eA simulations, where eA events are based on BeAGLE.
 EIC Jet workshop 5

Collision Geometry

 Impact parameter b

 Heavy-ion AA collisions

 “geometry drives nearly everything…”
 quoted from Peter Steinberg QM19
 EIC Jet workshop 6

Collision Geometry

 Impact parameter b

 virtual photon

 Heavy-ion AA collisions eA collisions

 “geometry drives nearly everything…” How to define collision geometry?
 quoted from Peter Steinberg QM19 Most eA physics at an EIC might
 also be driven by geometry!
 EIC Jet workshop 7

eA collision geometry in BeAGLE

 1. Impact parameter, b;
 2. Traveling distance, d;
 3. Nuclear thickness, T(b).

Experimental handle:
 o Forward neutron emissions, or evaporated neutrons, are correlated with these parameters.
 o Use the total (neutron) energy deposited in Zero-Degree Calorimeter.

 EIC Jet workshop 8

Centrality determination
 AA eA

 peripheral-like

 central-like

 Charged particles in midrapidity Evaporated neutrons in forward ZDC

In 10-20 years, the right-hand side figure might be the ”top-cited” figure in EIC era
 EIC Jet workshop 9

Centrality determination
A strong correlation between the (number of) forward-going neutrons
and b, d, T(b). (Lead by W. Chang)
 ePb 18 ´ 110 GeV ePb 18 ´ 110 GeV ePb 18 ´ 110 GeV
 0.25 0.25 0.25

 0-1% 0-1% 0-1%
 0.2 0.2 0.2
 60-100% 60-100% 60-100%

 0.15 0.15 0.15

 0.1 0.1 0.1

 0.05 0.05 0.05

 0 0 0
 0 2 4 6 8 10 12 14 0 2 4 6 8 10 12 14 0 2 4 6 8 10 12 14
 b [fm] d [fm] T(b)/r [fm]
 0

 Ø Clearly different distributions between “central” and “peripheral” collisions.
 Ø Physics that are sensitive to geometry might be separated by cutting different Ezdc
 Ø Advantage: ZDC position and energy resolution have almost no effect.
 EIC Jet workshop 10

Similar idea before EIC

 Ultra-Peripheral Collisions
 Impact parameter b > 2R

 à ℓ+ℓ-

di-lepton measurements in UPCs
with neutron emissions.

 EIC Jet workshop 11

Similar idea before EIC Shuai Yang at Hard probe 2020
 CMS collaboration
 -3 PbPb 5.02 TeV (1.5 nb-1)
 1.6 ´10
 (a)
 CMS
 1.5 Preliminary

 1.4

 áacoreñ
 Ultra-Peripheral Collisions 1.3
 Impact parameter b > 2R
 1.2
 STARlight

 (b)

 à ℓ+ℓ-

 áMµµñ (GeV)
 14

 13
di-lepton measurements in UPCs |yµ µ | < 2.4
 µ µ
 p > 3.5 GeV, |h | < 2.4

with neutron emissions.
 T
 8 < Mµ µ < 60 GeV
 12 0n0 0n1 0nX 1n1 1nX XnX
 n n n n n n

Neutron emissions can provide an experimental handle to the collision geometry
 EIC Jet workshop 12

Short-Range Correlations
• One of the most outstanding problems in modern
 nuclear physics. Sensitive to fundamental
 questions, e.g., “how do nucleons form a nuclei?”
• Deep connection to the puzzle, EMC effect.

• What is Short-Range Correlations, aka, SRC?
 • Nucleon-Nucleon interaction at very short distance;
 • High momentum nucleon in the nucleus rest frame; a
 small fraction of the cross section but could impact
 many aspects of nuclear effects.
 • pp, pn, nn pairs. Noriyoshi Ishii (Univ. of Tokyo) for HALQCD
 Collaboration S.Aoki (Univ. of Tsukuba), T.Doi (Univ.
 of Tsukuba)

 EIC Jet workshop 13

SRCs in deuteron - BeAGLE
 !
 l ts e' arXiv:2005.14706 BeAGLE has LF wavefunctions implemented,
 esu which is based on the non-relativistic nucleon
 r
 ew wavefunction
N γ*
 J/ψ Deuteron wavefunction n(k)
 103
 102 Alt 1
 N
 t=(p'-p)2 P
 Alt 2
 realistic n(k) Deuteron
 e Alt 3

 d p p' Alt 4
 10-2

 n(k) (fm )
 -3
 n n'
 2
 t'=(n'-d) -Mp
 10-6

 VM productions in associated with spectator tagging:
 • Probing the SRCs in deuteron – extreme config. 10-10
 P N
 • Sensitive to the gluon distributions – modifications?
 • What is the relation of SRCs to gluon shadowing ? Can 0 5
 -1
 10
 k (fm )
 this be related to the phenomenon of gluon saturation?
 • …
 EIC Jet workshop 14

EIC simulations
 !
 l ts e' arXiv:2005.14706 EIC forward detector simulations
 esu (Alex Jentsch et al)
 r
 ew
N γ* ZDC
 J/ψ
 Roman pots B1apf dipole
 Hadron beam
 t=(p'-p)2 (inside pipe)
 coming from IP
 e Off-Momentum Detectors
 d p p' B0pf dipole

 B0 Silicon
 n n' Detector
 t'=(n'-d)2-Mp

 BeAGLE events pass thru GEANT simulations of conceptual forward detectors at the EIC

 EIC Jet workshop 15

Spectator momentum arXiv:2005.14706

 BeAGLE BeAGLE
 10 8
 108
 eD 18x135 GeV g *d ® J/y+p'+n' eD 18x135 GeV g *d ® J/y+p'+n'
 leading proton leading neutron
 10 7
 107

 dN/dpm (GeV/c)-1
dN/dpm (GeV/c)-1

 105 105

 Truth 3
 Truth
 3
 10 Acceptance only 10 Acceptance only
 Full simulation Full simulation

 0 0.5 1 0 0.5 1
 pm (GeV/c) pm (GeV/c)

 Pm is the three-momentum of the spectator nucleon, either neutrons or protons
 EIC Jet workshop 16

Momentum transfer - t arXiv:2005.14706

 BeAGLE BeAGLE

 7
 eD 18x135 GeV g *d ® J/y+p'+n' 7
 eD 18x135 GeV g *d ® J/y+p'+n'
 10 leading neutron 10 leading proton

 106 106
 dN/dt (GeV-2)

 dN/dt (GeV-2)
 105 105

 104 104
 Truth Truth
 103 Acceptance only 103 Acceptance only
 Full simulation Full simulation

 0 1 2 0 1 2
 2 2 2 2
 t=(p'-(-n)) (GeV ) t=(p'-(-n)) (GeV )

Using the spectator nucleons only to reconstruct t distributions in both cases – double tagging
 EIC Jet workshop 17

Gluon imaging
 H1 @ HERA
 e+p=e’+J/psi+p’

 • Measurement of the momentum transfer t distributions
 à gluon source distributions’ (F(b) vs b)
 EIC Jet workshop 18

Gluon imaging in Deuteron arXiv:2005.14706

 EIC
 Gluon
 e+d =e’+J/psi+p’+n’ 1.5
 e' SRC 10% smaller proton
 Free proton

 γ* SRC 10% larger proton

 J/ψ 1

 F(b)
 t=(p'-p)2
 e 0.5
 d p p'

 n n'
 t'=(n'-d)2-Mp 0
 -1
 (Kong.Tu et al, manuscript
 0 in preparation) 1
 b (fm)
 • Measurement of the momentum transfer t distributions
 à gluon source distributions’ (F(b) vs b)

 Bring another nucleon closer to the proton, larger or smaller or the same? 19
 EIC Jet workshop

Gluon imaging in Deuteron arXiv:2005.14706

 EIC
 Gluon
 ' e+d =e’+J/psi+p’+n’
 e SRC 10% smaller proton
 1.4 Free proton

 F(b) ratio to free proton
 SRC 10% larger proton
 γ*
 J/ψ
 1.2
 t=(p'-p)2
 e
 d p p' 1

 n n'
 t'=(n'-d)2-Mp 0.8
 (Kong.Tu
 -1 et al, manuscript
 0 in preparation) 1
 b (fm)
 • Measurement of the momentum transfer t distributions
 à gluon source distributions’ (F(b) vs b)

 Bring another nucleon closer to the proton, larger or smaller or the same? 20
 EIC Jet workshop

Another example in UPC data
• STAR d+Au UPC data – exclusive J/psi 1
 Deuteron STAR Preliminary
 production off deuterons!
 Gluon density
 d+Au sNN = 200 GeV STAR Preliminary Charge density
 á Wg *p ñ » 25 GeV g *d ® J/ y + X
 |y |

Upcoming/potential projects
• Free neutron structure function – spectator tagging in DIS on deuteron
• Bounded proton structure function – correlation with SRCs
• An extension to heavy nucleus.
• BeAGLE benchmark processes…
• …

• Besides inclusive measurements, we can also look at jets or other hard
 probes.
 • Jet as a probe to the strangeness in DIS (Arratia et al 2020). Embed this in
 deuteron or Pb with spectator tagging? Explicitly change the parton structure by
 the given SRCs.
 • …MANY other possibilities
 • We entourage/welcome jet experts at the EIC using BeAGLE.
 EIC Jet workshop 22

Upcoming/potential projects
• Free neutron structure function – spectator tagging in DIS on deuteron
• Bounded proton structure function – correlation with SRCs
• An extension to heavy nucleus.
• BeAGLE benchmark processes…
• …

• Besides inclusive measurements, we can also look at jets or other hard
 probes.
 • Jet as a probe to the strangeness in DIS (Arratia et al 2020). Embed this in
 deuteron or Pb with spectator tagging? Explicitly change the parton structure by
 the given SRCs.
 • …MANY other possibilities
 • We entourage/welcome jet experts at the EIC using BeAGLE.
 EIC Jet workshop 23

Summary and outlook
• BeAGLE has been used for important applications for the EIC
 physics and R&D, going from geometry tagging to spectator
 tagging, from light to heavy nucleus.
• And many more… (GCF in BeAGLE, incoherent vetoing for
 eA, etc.)

• BeAGLE is potentially capable of providing a great
 framework/platform for jet physics in eA.
 • Pythia/Rapgap for hard processes
 • DPMJet for geometry, shadowing, intra-nuclear cascades..
 • Fluka for nuclear remnants, excited nucleus, and so on.

 EIC Jet workshop 24

Summary and outlook
• BeAGLE has been used for important applications for the EIC
 physics and R&D, going from geometry tagging to spectator
 tagging, from light to heavy nucleus.
• And many more… (GCF in BeAGLE, incoherent vetoing for
 eA, etc.)

• BeAGLE is potentially capable of providing a great
 framework/platform for jet physics in eA.
 • Pythia/Rapgap for hard processes
 • DPMJet for geometry, shadowing, intra-nuclear cascades..
 • Fluka for nuclear remnants, excited nucleus, and so on.

 We would love to have your interests/expertise on BeAGLE for jets
 EIC Jet workshop 25