Huey-Wen Lin USQCD All Hands' Meeting Lattice Parton Physics - - PowerPoint PPT Presentation

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Huey-Wen Lin USQCD All Hands' Meeting Lattice Parton Physics - - PowerPoint PPT Presentation

Jan 27, 2023 20 likes •213 views

Huey-Wen Lin USQCD All Hands' Meeting Lattice Parton Physics Project (LP3) https://www.pa.msu.edu/~hwlin/LP3/ Huey-Wen Lin (PI) Xiangdong Ji Luchang Jin Peng Sun Yi-Bo Yang (MSU) (UMD) (BNL) (MSU) (MSU) International collaborators

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SLIDE 1

Huey-Wen Lin — USQCD All Hands' Meeting

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SLIDE 2

https://www.pa.msu.edu/~hwlin/LP3/

Lattice Parton Physics Project (LP3)

Huey-Wen Lin — USQCD All Hands' Meeting

Xiangdong Ji (UMD) Huey-Wen Lin (PI) (MSU) Peng Sun (MSU) Luchang Jin (BNL) Yong Zhao (MIT) Jiunn-Wei Chen (NTU) Jian-Hui Zhang (Regensburg) Tomomi Ishikawa (SJTU)

International collaborators

Yi-Bo Yang (MSU)

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SLIDE 3

Parton Distribution Functions

§ PDFs are universal quark/gluon distributions of nucleon

 Many ongoing/planned experiments (BNL, JLab, J-PARC, COMPASS, GSI, EIC, LHeC, …)

Huey-Wen Lin — USQCD All Hands' Meeting

How are the sea quarks and gluons, and their spins, distributed in space and momentum inside the nucleon?

Imaging of the proton

EIC White Paper, 1212.1701

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SLIDE 4

§ PDFs are universal quark/gluon distributions of nucleon

 Many ongoing/planned experiments (BNL, JLab, J-PARC, COMPASS, GSI, EIC, LHeC, …)

§ Important inputs to discern new physics at LHC

 Currently dominate errors in Higgs production

Parton Distribution Functions

Huey-Wen Lin — USQCD All Hands' Meeting

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SLIDE 5

Huey-Wen Lin — USQCD All Hands' Meeting

Global Analysis

§ Discrepancies appear when data is scarce § Many groups have tackled the analysis

 CTEQ, MSTW, ABM, JR, NNPDF, etc.

Jimenez-Delgado, Melnitchouk, Owens, J.Phys. G40 (2013) 09310

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Global Analysis

§ Discrepancies appear when data is scarce § Many groups have tackled the analysis

 CTEQ, MSTW, ABM, JR, NNPDF, etc.

Jimenez-Delgado, Melnitchouk, Owens, J.Phys. G40 (2013) 09310

Huey-Wen Lin — USQCD All Hands' Meeting

§ A first joint workshop with global-fitting community to address key LQCD inputs

 http://www.physics.ox.ac.uk /confs/PDFlattice2017  Whitepaper will study the needed precision of lattice PDFs in the large-𝑦 region

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SLIDE 7

Huey-Wen Lin — USQCD All Hands' Meeting

A Pro romi misi sing Ne New Dir irec ectio tion

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SLIDE 8

Long existing obstacles! § Lattice calculations rely on operator product expansion,

  • nly provide moments 〈xn〉

§ For higher moments, all ops mix with lower-dimension ops

 No practical proposal to overcome this

New Strategy (LaMET): § Calculate finite-momentum boosted quark distribution

 In P

z→∞ limit, parton distribution is recovered

 For finite P

z, corrections are needed

§ Feasible with today’s resources!

𝑦𝑜 𝑟 = න

−1 1

𝑒𝑦 𝑦𝑜𝑟 𝑦

Xiangdong Ji, Phys. Rev. Lett. 111, 039103 (2013)

Huey-Wen Lin — USQCD All Hands' Meeting

PDFs on the Lattice

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Parton Distribution Functions

Huey-Wen Lin — USQCD All Hands' Meeting

Large-Momentum Effective Theory for PDFs Γ 𝑞(𝑄

𝑨)

𝑅2 = 0

Γ ∈ {𝛿𝑨, 𝛿𝑨𝛿5, 𝛿𝑨𝛿⊥𝛿5} 𝑞(𝑄

𝑨)

𝑄

𝑨 →∞ limit

𝑟 𝑦, 𝜈 = ෤ 𝑟 𝑦, 𝜈, 𝑄

𝑨 + 𝒫 𝛽𝑡 + 𝒫

Τ 𝑁𝑂

2 𝑄 𝑨 2 + 𝒫

Τ ΛQCD

2

𝑄

𝑨 2

  • X. Xiong et al., 1310.7471; J.-W. Chen et al, 1603.06664
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§ First time in LQCD history to study antiquark distribution!

 𝑁𝜌 ≈ 310 MeV

Lost resolution in small-x region

Future improvement: larger lattice volume න 𝑒𝑦 ത 𝑣 𝑦 − ҧ 𝑒(𝑦) ≈ −0.16(7)

HWL et al. 1402.1462

Sea Flavor Asymmetry

  • R. Towell et al. (E866/NuSea), Phys.Rev. D64, 052002 (2001)

𝒚

Sea Flavor Asymmetry

Huey-Wen Lin — USQCD All Hands' Meeting

ത 𝑟 𝑦 = −𝑟 −𝑦

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SLIDE 11

§ First time in LQCD history to study antiquark distribution!

 𝑁𝜌 ≈ 310 MeV

Lost resolution in small-x region

Future improvement: larger lattice volume න 𝑒𝑦 ത 𝑣 𝑦 − ҧ 𝑒(𝑦) ≈ −0.16(7)

HWL et al. 1402.1462

Sea Flavor Asymmetry

  • R. Towell et al. (E866/NuSea), Phys.Rev. D64, 052002 (2001)

𝒚

Sea Flavor Asymmetry

ത 𝑟 𝑦 = −𝑟 −𝑦

Huey-Wen Lin — USQCD All Hands' Meeting

A milestone for lattice QCD!

First sea flavor asymmetry ever calculated!

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§ Lattice exploratory study

 𝑁𝜌 ≈ 310 MeV

Compared with E866

Too good to be true?

Lost resolution in small-x region

Future improvement to have larger lattice volume න 𝑒𝑦 ത 𝑣 𝑦 − ҧ 𝑒(𝑦) ≈ −0.16(7)

HWL et al 1402.1462

Sea Flavor Asymmetry

  • R. Towell et al. (E866/NuSea), Phys.Rev. D64, 052002 (2001)

Similar results repeated by ETMC, at 𝑁𝜌 ≈ 373 MeV

ETMC, 1504.07455

Sea Flavor Asymmetry

Huey-Wen Lin — USQCD All Hands' Meeting

𝒚

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SLIDE 13

 We found sea asymmetry of  Chiral quark-soliton model  SoLID at JLab, Drell-Yan exp’t at FNAL (E1027+E1039), EIC, ...

§ Exploratory study

P . Schweitzer et al., PRD 64, 034013 (2001)

න 𝑒𝑦 𝜀ത 𝑣 𝑦 − 𝜀 ҧ 𝑒(𝑦) ≈ −0.10(8)

Preliminary

Removing O(MN

n/P z n) errors + O(αs)

+ O(Λ2

QCD/P z 2)

 𝑁𝜌 ≈ 310 MeV

Pos(LATTICE 2013), 1603.06664

𝜀ത 𝑟 𝑦 = −𝜀𝑟 −𝑦

1505.05589; 1503.03495

Huey-Wen Lin — USQCD All Hands' Meeting

The calculation was also repeated by ETMC, at 𝑁𝜌 ≈ 373 MeV

ETMC, 1610.03689

Transversity Distribution

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SLIDE 14

Huey-Wen Lin — USQCD All Hands' Meeting

Pro rogress ress Last st Yea ear: r: Sy Syst stem emati atics cs

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SLIDE 15

Huey-Wen Lin — USQCD All Hands' Meeting

Power Divergence

§ Improved quasi-quark distribution

 ෤ 𝑟imp 𝑦, Λ, 𝑞𝑨 = ׬

−∞ ∞ 𝑒𝑨 4𝜌 𝑓𝑗𝑨𝑙𝑨−𝜀𝑛 𝑨

ൿ ൻ𝑞 ത 𝜔 0,0⊥, 𝑨 𝛿𝑨𝑀 𝑨, 0 𝜔 0 𝑞

§ Wilson-line renormalization to remove power divergence

 𝑏 ≈ 0.09 fm, 𝑀 ≈ 6 fm, 𝑁𝜌 ≈ 130 MeV, clover/HISQ

Luchang Jin Jian-Hui Zhang Plot by Jian-Hui Zhang

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Renormalization

§ Ongoing investigation of renormalization

 Investigating RI’MOM scheme renormalization (Yang)  RI’MOM to MS matching (Zhao)

§ Preliminary result

 Test case: 𝑏 ≈ 0.12 fm, 𝑁𝜌 ≈ 310 MeV, clover/HISQ

Huey-Wen Lin — USQCD All Hands' Meeting

Yong Zhao Yi-Bo Yang Plot by Yi-Bo Yang Preliminary

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SLIDE 17

Huey-Wen Lin — USQCD All Hands' Meeting

20 2017 17/1 /18 Alloc

  • cati

ation

  • n
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§ Proposed ensemble

 Nf = 2+1+1 clover/HISQ lattices (MILC) Mπ ≈ 130 MeV, a ≈ 0.09 fm (L ≈ 6 fm)

tsep

Proposed Calculation

Huey-Wen Lin — USQCD All Hands' Meeting

§ Proposed physics case

 At least 3 𝑢sep, multiple mom. source smearing  Extended unpol. PDFs to larger 𝑞𝑨 (w/mom. source) and polarized structure (helicity + transversity)  First LQCD study of x-dep’t GPDs (3D Spatial Maps of the Nucleon)

“The Tomography of the Nucleon — Spatial Imaging of Gluons and Sea Quarks”

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SLIDE 19

§ Proposed ensemble

 Nf = 2+1+1 clover/HISQ lattices (MILC) Mπ ≈ 130 MeV, a ≈ 0.09 fm (L ≈ 6 fm)

tsep

Proposed Calculation

Huey-Wen Lin — USQCD All Hands' Meeting

§ Proposed physics case

 At least 3 𝑢sep, multiple mom. source smearing  Extended unpol. PDFs to larger 𝑞𝑨 (w/mom. source) and polarized structure (helicity + transversity)  First LQCD study of x-dep’t GPDs (3D Spatial Maps of the Nucleon)