Photon PDF and Proton PDFs studied at an EIC

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1 Photon PDF and Proton PDFs studied at an EIC Xiaouan Chu BNL & CCNU November 4, 8 Xiaouan Chu (BNL & CCNU Photon PDF and Proton PDFs studied at an EIC November 4, 8 / 4

2 Outline. Deep Inelastic Scattering. Wide energy range and high luminosity at EIC Unpolarized Photon Structure Unpolarized Proton PDFs etracted from CC events 3. Polarization at EIC Proton Spin 4. Summary and outlook Xiaouan Chu (BNL & CCNU Photon PDF and Proton PDFs studied at an EIC November 4, 8 / 4

$Deep Inelastic Scattering Q = sy s: center-of-mass energy squared Q : Resolution power : he fraction of the nucleon s momentum carried by the struck quark y: Inelasticity Electron beams provide$

3 Deep Inelastic Scattering Q = sy s: center-of-mass energy squared Q : Resolution power : he fraction of the nucleon s momentum carried by the struck quark y: Inelasticity Electron beams provide point-like probe - resolution Dit, model independent determination of partonic kinematics of physics processes High pision & access to partonic kinematics through scattered lepton Probe has comple structure No simple access to partonic kinematics Xiaouan Chu (BNL & CCNU Photon PDF and Proton PDFs studied at an EIC November 4, 8 3 / 4

$acceptance for scattered protons from diffractive reactions, breakup neutrons and spectator$ tagging erhic etends kinematics coverage for data with polarized beams by decades in at a fied Q

tagging erhic etends kinematics coverage for data with polarized beams by decades in at a fied Q

4 erhic s kinematic reach in and Q wo Physics cases of EIC in US: erhic and JLEIC Maimal full acceptance for scattered protons from diffractive reactions, breakup neutrons and spectator tagging erhic etends kinematics coverage for data with polarized beams by decades in at a fied Q by decades in Q at a fied. Xiaouan Chu (BNL & CCNU Photon PDF and Proton PDFs studied at an EIC November 4, 8 4 / 4

5 Wide energy range and high luminosity wide center-of-mass coverage: Access to and Q over a wide range high luminosity: Mapping the spatial and momentum structure of nucleons and nuclei in 3d Access to rare probes Xiaouan Chu (BNL & CCNU Photon PDF and Proton PDFs studied at an EIC November 4, 8 5 / 4

6 Photon and proton structure resolved process e γ q q q q P he photon structure is probed pisely: Dit photon state, resolved photon state Parton Distribution Functions(PDFs of Photon: q(,q, g(,q ; γ definition How to separate: Resolved: γ < ; dit: γ =. γ = E (p ey e η + p e η, y = Eγ E e Parton densities can be etracted by measuring di-jet cross section: d σ d γ dq = γ flu f γ( γ, Q, µ f p( p, µ σ ij dit process e γ q q he proton structure is probed by dit state photon: d σ d Bj dq = 4πα Q 4 [( y + y F ( Bj, Q + y F L( Bj, Q ], F : q( q(, F L : g( P Xiaouan Chu (BNL & CCNU Photon PDF and Proton PDFs studied at an EIC November 4, 8 6 / 4

7 γ γ Unpolarized photon structure at EIC GeV 5 GeV,. < y <.95, two highest p jets, p jet η jets < 4.5, stable particle p > 5 MeV. gen γ counts Resolved Dit γ Di-jet method provides a good way to onstruct γ We can separate resolved/dit processes( γ <.6. [nb] σ d di-jet dlog((p d > 5GeV, p jet Ldt = fb γ =.7- ( 6 γ =.6-.7 ( 5 γ =.5-.6 ( 4 γ =.4-.5 ( 3 γ =.3-.4 ( γ =.-.3 ( γ =.-. ( γ =.-. > p jet di-jet (p > 4.5 GeV, [GeV ] he simulation shows the capability to measure the cross section for di-jet production at L = fb, with high accuracy in a wide kinematic range at EIC and etract the unpolarized photon PDFs from a global fit. Xiaouan Chu (BNL & CCNU Photon PDF and Proton PDFs studied at an EIC November 4, 8 7 / 4

8 EIC advantages compared to HERA EIC [nb] σ d jets dlog((e γ d HERA stat. uncertainty stat. uncertainty GeV < E jets H data.5 < GeV PYHIA HERA, µ PYHIA HERA, µ PYHIA HERA, µ - EIC, Ldt = fb = = = γ γ g HERA γ range EIC γ range - γ High luminosity to define the uncertainty band Feasiblity to probe small γ region Xiaouan Chu (BNL & CCNU Photon PDF and Proton PDFs studied at an EIC November 4, 8 8 / 4

9 Proton PDFs etracted from inclusive CC ep scattering High and high Q events he reduced cross section for inclusive Charged Current ep scattering are defined as σ r,cc = π Bj [ M G W +Q ] d σ CC F MW d Bj, in HERAFitter, the value of dq G F =.6 5 GeV and M W = 8.385GeV. CC structure function are defined as σ r,cc (U + ( y D, U = u + c, D = d + s Xiaouan Chu (BNL & CCNU Photon PDF and Proton PDFs studied at an EIC November 4, 8 9 / 4

10 Simulations results: Inclusive cross section Simulations: unpolarized ep data sample from DJANGOH, unpol: L = fb, GeV 5 GeV, Proton PDF: MRS σ/ddq d - e p νx (CC, σ/ddq d - e p νx (CC, - - heory/data -..8 EICsym Data Q δ δ uncorrelated total heory + shifts =.. HERAPDF. HERAPDF.-profiled heory/data - EICsym Data Q δ δ uncorrelated total heory + shifts = 3 HERAPDF. HERAPDF.-profiled σ/ddq d - e p νx (CC, - σ/ddq d - - e p νx (CC, - heory/data -4-5 EICsym Data Q δ δ uncorrelated total heory + shifts = HERAPDF. HERAPDF.-profiled heory/data - EICsym Data Q δ δ uncorrelated total heory + shifts = 4 HERAPDF. HERAPDF.-profiled Xiaouan Chu (BNL & CCNU Photon PDF and Proton PDFs studied at an EIC November 4, 8 / 4

11 Etracting Proton PDFs by a global fitting u V (,Q.9 Q =.9 GeV HERAPDF..8 HERAPDF.-profiled.7 d V (,Q.4 Q =.9 GeV HERAPDF. HERAPDF.-profiled g(,q 3.5 Q =.9 GeV HERAPDF. 3 HERAPDF.-profiled.5 Σ(,Q.6.4. Q =.9 GeV HERAPDF. HERAPDF.-profiled Xiaouan Chu (BNL & CCNU Photon PDF and Proton PDFs studied at an EIC November 4, 8 / 4

12 How well can EIC constrain PDFs? U = u + c, D = d + s U and D are better constrained compared with HERA Xiaouan Chu (BNL & CCNU Photon PDF and Proton PDFs studied at an EIC November 4, 8 / 4

Why polarization: proton spin Spin is one of the fundamental properties of the matter.

interactions of quarks and gluons and the intrinsic properties.

contribution: he integral of g L over from to gluon distribution: dg L (,Q dlnq g(, Q Only with the

13 Why polarization: proton spin Spin is one of the fundamental properties of the matter. Proton spin is composed by total quark spin, gluon spin and angular momentum, it is the interplay between interactions of quarks and gluons and the intrinsic properties. Access to spin structure of proton: measuring the cross section difference g L as function of and Q quark contribution: he integral of g L over from to gluon distribution: dg L (,Q dlnq g(, Q Only with the center-of-mass energies available at erhic the different contributions to the spin of the proton can be disentangled Xiaouan Chu (BNL & CCNU Photon PDF and Proton PDFs studied at an EIC November 4, 8 3 / 4

Summary and outlook he EIC will profoundly impact our understanding of QCD and its dynamics with high luminosity & high energy, nuclei & beam ploarization he structure of

14 Summary and outlook he EIC will profoundly impact our understanding of QCD and its dynamics with high luminosity & high energy, nuclei & beam ploarization he structure of nucleons and nuclei Spin of the proton Will enable images of yet uneplored nonlinear regions Xiaouan Chu (BNL & CCNU Photon PDF and Proton PDFs studied at an EIC November 4, 8 4 / 4

15 back up slides: Reproduce HERA data Reproduce the inclusive cross section, photon PDF set is SAS, proton PDF is CEQ5m, 5 GeV < Q <GeV, L = fb. γp σ [µb] 8 6 Q =. GeV PYHIA HERA Data [µb] γp σ 4 Q =.5 GeV PYHIA HERA Data subprocess fraction.8 PYHIA resolved.6 VMD dit.4. subprocess fraction.8 PYHIA.6.4. resolved VMD dit -5-4 Bj -5-4 Bj [HERA Data: Phys. Rev. D 96 4(7] Xiaouan Chu (BNL & CCNU Photon PDF and Proton PDFs studied at an EIC November 4, 8 4 / 4

16 Reproduce HERA data Reproduce the di-jet cross section, photon PDF set is SAS, proton PDF is CEQ5m, 5 GeV < Q <GeV. [nb] jets d σ dlog((e γ d PYHIA H Data 6 γ =.75 ( 5 γ =.6.75 ( 4 γ =.5.6 ( 3 γ =.4.5 ( γ =.3.4 ( Kinematics cuts from HERA: 7.5GeV 8 GeV,. < y <.83, η jets <, < η jet + η jet < 4, E jet E jet E jet, Ejet > 7.5GeV, + E jet > GeV, E jet /(Ejet +E jet <.5 Our simulation can match the eisting data γ =.. γ =..3 ( (E 3 jets [GeV ] Xiaouan Chu (BNL & CCNU Photon PDF and Proton PDFs studied at an EIC November 4, 8 4 / 4

17 Motivation: Eisting photon PDFs =. GeV =. GeV u Q =. GeV P =. GeV DO GLO LAC G/GAL GLO GS GLO GS G 96LO GRV G/GRS GLO ACFGP/AFG GNLO WHI GLO SAS G(v/vLO d Q =. GeV P =. GeV DO GLO LAC G/GAL GLO GS GLO GS G 96LO GRV G/GRS GLO ACFGP/AFG GNLO WHI GLO SAS G(v/vLO s Q =. GeV P =. GeV DO GLO LAC G/GAL GLO GS GLO GS G 96LO GRV G/GRS GLO ACFGP/AFG GNLO WHI GLO SAS G(v/vLO g Q P DO GLO LAC G/GAL GLO GS GLO GS G 96LO GRV G/GRS GLO ACFGP/AFG GNLO WHI GLO SAS G(v/vLO ( γ is the momentum fraction of the parton from the photon 3 Xiaouan Chu (BNL & CCNU Photon PDF and Proton PDFs studied at an EIC November 4, 8 4 / 4

18 Motivation: Eisting eperiment results [arxiv:9544, arxiv:978, Eur. Phys. J. C, 3637 (999, DESY 97-64] Lack of statistic, especially in the small γ region which is important for the constrain of photon PDFs. Results from jet and charged particle measurements show that the best fit are GRV and SAS he nature of e + e collisions is two photon physics, the photon structure is very important for ILC γγ option. Polarized photon PDFs are never measured before. Xiaouan Chu (BNL & CCNU Photon PDF and Proton PDFs studied at an EIC November 4, 8 4 / 4

19 Why polarization: polarized photon PDFs d σ d γdq pol. photon PDFs pol. proton PDF min: f γ = ; ma: f γ = f γ DSSV = γ flu f γ ( γ, Q, µ f p ( p, µ σ ij [nb] di-jet d σ dlog((p γ d (p - Ldt = fb di-jet 7 γ =.7- ( 6 γ =.6-.7 ( 5 γ =.5-.6 ( 4 γ =.4-.5 ( 3 γ =.3-.4 ( γ =.-.3 ( γ =.-. ( γ =.-. 3 ] [GeV σ = (σ++ σ + he simulation shows the capability to measure the polarized cross section for di-jet production, with high accuracy in a wide kinematic range at EIC. First measurement of polarized photon PDFs with high pision. Flavor tagging can also be applied in polarized case. Xiaouan Chu (BNL & CCNU Photon PDF and Proton PDFs studied at an EIC November 4, 8 4 / 4

20 A LL = σ/σ A LL L = fb, <.6 γ ma.pol.γ min.pol.γ A LL γ > di jet p [GeV] di jet p [GeV] A LL.5.4 γ <.6 A LL.5.4 γ > di jet η di jet η he difference between ma.pol. photon and min.pol. photon can be measured in eperiment, the pol.photon PDFs can be constrained at EIC. Xiaouan Chu (BNL & CCNU Photon PDF and Proton PDFs studied at an EIC November 4, 8 4 / 4

Extrac'ng Photon PDF and Proton PDFs at an EIC. Xiaoxuan Chu 褚晓璇 USTC, 9/11/2018

Extrac'ng Photon PDF and Proton PDFs at an EIC Xiaoxuan Chu 褚晓璇 USC, 9//8 Outline. Possible realizations of an EIC. Photon structure studied at erhic Motivation and Introduction (Un)polarized photon structure