New insights of soft hadron production in pp and p-Pb collisions at - - PowerPoint PPT Presentation

2018/12/21 Wuhan Wuhan The 4t he 4th China h China LHC Ph LHC Physics ysics Wo Workshop ( rkshop (ATHIC ATHIC 2018) 2018)

New insights of soft hadron production in pp and p-Pb collisions at LHC Jun Song （宋军） Jining University (Qufu, Shandong )

Collaborators : Feng-lan Shao, Zuo-tang Liang, Xing-rui Gou, Hai-hong Li,et al

Outline

• 1. Motivation
• 2. Quark number scaling property for hadron 𝒒𝑼 spectra
• 3. Quark combination mechanism in pp and p-Pb collisions at LHC
• 4. Summary

2018/12/21 Wuhan Wuhan The 4t he 4th China h China LHC Ph LHC Physics ysics Wo Workshop ( rkshop (ATHIC ATHIC 2018) 2018) 2

Motivation

Recently, striking features observed by ALICE, CMS, LHCb collaborations for high multiplicity events in pp and p-Pb collisions at LHC, e.g,

• long range angular correlations (ridge), CMS JHEP1009(2010), CMS PLB718(2013),742(2015)
• flow-like patterns, NPA932(14), CMS PLB742(2015),765(2017)
• enhanced strangeness,

ALICE Nature Phys.13(2017)

• enhanced baryon/meson ratios,

…… Is Quark Gluon Plasma (QGP) also formed in pp and p-Pb collisions at LHC? Our studies suggest the change of hadronization mechanism from fragmentation to quark combination ! Pb-Pb p-Pb p-p Theoretical explanations focus on the creation of mini-QGP or phase transition, color re- connection or string overlap at hadronization

2018/12/21 Wuhan Wuhan The 4t he 4th China h China LHC Ph LHC Physics ysics Wo Workshop ( rkshop (ATHIC ATHIC 2018) 2018) 3

Manipulate data of 𝒒𝑼 spectra of 𝛁(𝐭𝐭𝐭) and 𝝔(𝒕ത 𝒕) in p-Pb collisions at 5.02 TeV (1) divide 𝒒𝑼 bin by quark number, 𝒒𝑼𝛁/3, 𝒒𝑼𝝔/2, (2) take the inverse quark number power of density 𝒆𝑶𝒊/𝒆𝒒𝑼𝒆𝒛, i.e. 𝒆𝑶𝜵

𝟐/𝟒/𝒆𝒒𝑼𝒆𝒛 and 𝒆𝑶𝝔 𝟐/𝟑/𝒆𝒒𝑼𝒆𝒛

(3) divide 𝛁 data by a constant to keep the same magnitude with that of 𝝔

𝒈𝛁

𝟐/𝟒 𝟒𝒒𝑼 = 𝝀𝝔,𝛁𝒈𝝔 𝟐/𝟑(𝟑𝒒𝑼)

mathematic relation in other words, 𝒈𝛁 𝟒𝒒𝑼 = 𝝀𝛁𝒈𝒕

𝟒 𝒒𝑼

𝒈𝝔 𝟑𝒒𝑼 = 𝝀𝝔𝒈𝒕

𝟑 𝒒𝑼

where 𝜆 is independent of 𝑞𝑈

𝑞𝑈(GeV/c)

ALICE data : Phys. Lett. B 758, 389(2016).

• Eur. Phys. J. C76, 245 (2016)

p-Pb 5.02TeV

Quark number scaling of hadronic 𝒒𝑼 spectra

Song,Gou,Shao,Liang, Phys.Lett. B774(2017),516

𝒈 𝒒𝑼 ≡ 𝒆𝑶𝒊/𝒆𝒒𝑼𝒆𝒛

2018/12/21 Wuhan Wuhan The 4t he 4th China h China LHC Ph LHC Physics ysics Wo Workshop ( rkshop (ATHIC ATHIC 2018) 2018) 4

Scaling property at different multiplicity classes high multiplicity events QNS holds well small multiplicity events QNS is broken

Scaling property in different multiplicity classes

in p-Pb collisions at 5 TeV

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Scaling property in different multiplicity classes

in pp collisions at 7 TeV

pp at 7TeV pp at 7TeV pp at 7TeV pp at 7TeV high multiplicity events QNS holds well small multiplicity events QNS is broken

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Scaling property in pp collisions at different collision energies

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Scaling property between Ξ∗0(𝑣𝑡𝑡) and 𝐿∗0(𝑒 ҧ 𝑡)

𝑔Ξ∗0( 2 + 𝑠 𝑞𝑈) 𝑔𝐿∗0 1 + 𝑠 𝑞𝑈 = 𝜆𝐿∗,Ξ∗𝑔

𝑡(𝑞𝑈)

where 𝑠 ≈ 2/3

𝑞𝑈(GeV/c)

ALICE data, Eur. Phys. J. C77, 389(2017)

2018/12/21 Wuhan Wuhan The 4t he 4th China h China LHC Ph LHC Physics ysics Wo Workshop ( rkshop (ATHIC ATHIC 2018) 2018) 8

Quark Combination Mechanism

Quark number scaling property exhibited is a clear signal of quark combination hadronization for small parton system created in pp and p-Pb collisions at LHC energies 𝑔

𝐶𝑘 𝑞𝐶 = ∫ 𝑒𝑞1𝑒𝑞2𝑒𝑞3 𝑆𝐶𝑘 𝑞1, 𝑞2, 𝑞3; 𝑞𝐶

𝑔

𝑟1𝑟2𝑟3 𝑞1, 𝑞2, 𝑞3

𝑔

𝑁𝑘 𝑞𝑁 = ∫ 𝑒𝑞1𝑒𝑞2 𝑆𝑁𝑘 𝑞1, 𝑞2; 𝑞𝑁

𝑔

𝑟1 ത 𝑟2 𝑞1, 𝑞2

Start from general formula Assume independent distribution of (anti-)quarks 𝑔

𝑟1𝑟2𝑟3 𝑞1, 𝑞2, 𝑞3 = 𝑔 𝑟1 𝑞1 𝑔 𝑟2 𝑞2 𝑔 𝑟3 𝑞3

𝑔

𝑟1 ത 𝑟2 𝑞1, 𝑞2

= 𝑔

𝑟1 𝑞1 𝑔ത 𝑟2 𝑞2

Adopt the co-moving combination 𝑆𝐶𝑘 𝑞1, 𝑞2, 𝑞3; 𝑞𝐶 = 𝜆𝐶𝑘 ෑ

𝑗=1 3

𝜀(𝑞𝑗 − 𝑦𝑗𝑞𝐶) 𝑆𝑁𝑘 𝑞1, 𝑞2; 𝑞𝑁 = 𝜆𝑁𝑘 ෑ

𝑗=1 2

𝜀(𝑞𝑗 − 𝑦𝑗𝑞𝑁) equal velocity combination 𝒚𝒋 = 𝒏𝒋/ σ𝒌 𝒏𝒌, 𝑛𝑡 = 500 MeV 𝑛𝑣 = 𝑛𝑒 = 330 MeV.

2018/12/21 Wuhan Wuhan The 4t he 4th China h China LHC Ph LHC Physics ysics Wo Workshop ( rkshop (ATHIC ATHIC 2018) 2018) 9

Rewrite the spectrum 𝑔

𝑁𝑘 𝑞𝑁 = 𝑂𝑁𝑘𝑔 𝑁𝑘 (𝑜) 𝑞𝑁

𝑔

𝐶𝑘 𝑞𝐶 = 𝑂𝐶𝑘𝑔 𝐶𝑘 (𝑜) 𝑞𝐶

with normalized distribution ∫ 𝑒𝑞 𝑔 𝑜 𝑞 = 1,

𝑔

𝑁𝑘 (𝑜) 𝑞𝑁 = 𝐵𝑁𝑘𝑔 𝑟1 (𝑜) 𝑦1𝑞𝑁 𝑔ത 𝑟2 (𝑜) 𝑦2𝑞𝑁

𝑔

𝐶𝑘 (𝑜) 𝑞𝐶 = 𝐵𝐶𝑘𝑔 𝑟1 (𝑜) 𝑦1𝑞𝐶 𝑔 𝑟2 (𝑜) 𝑦2𝑞𝐶 𝑔 𝑟3 (𝑜) 𝑦3𝑞𝐶

, and yield 𝑂𝑁𝑘 = 𝑂𝑟1 ത

𝑟2 𝜆𝑁𝑘 𝐵𝑁𝑘

= 𝑂𝑟1 ത

𝑟2 𝑄𝑟1 ത 𝑟2→𝑁𝑘

𝑂𝐶𝑘 = 𝑂𝑟1𝑟2𝑟3

𝜆𝑁𝑘 𝐵𝑁𝑘

= 𝑂𝑟1𝑟2𝑟3𝑄𝑟1𝑟2𝑟3→𝐶𝑘 𝑄𝑟1 ത

𝑟2→𝑁𝑘 and 𝑄𝑟1𝑟2𝑟3→𝐶𝑘 are momentum-

integrated combination probabilities adopt flavor-blind approximation 𝑄𝑟1 ത

𝑟2→𝑁𝑘= 𝐷𝑁𝑘

ഥ 𝑂𝑁 𝑂𝑟 ത

𝑟

𝑄𝑟1𝑟2𝑟3→𝐶𝑘 = 𝐷𝐶𝑘 ഥ 𝑂𝐶 𝑂𝑟𝑟𝑟 𝐷𝑁𝑘 and 𝐷𝐶𝑘 select the different spin states for the same flavor combination

𝐷𝑁𝑘 = 1 1 + 𝑆𝑊/𝑄 𝑔𝑝𝑠 𝐾𝑄 = 0− 𝑛𝑓𝑡𝑝𝑜𝑡 𝑆𝑊/𝑄 1 + 𝑆𝑊/𝑄 𝑔𝑝𝑠 𝐾𝑄 = 1− 𝑛𝑓𝑡𝑝𝑜𝑡 𝐷𝐶𝑘 = ൞

𝑆𝑃/𝐸 1+𝑆𝑃/𝐸

𝑔𝑝𝑠 𝐾𝑄 = (1/2)+𝑐𝑏𝑠𝑧𝑝𝑜𝑡

1 1+𝑆𝑃/𝐸

𝑔𝑝𝑠 𝐾𝑄 = (3/2)+𝑐𝑏𝑠𝑧𝑝𝑜𝑡

Parameters 𝑆𝑊/𝑄 = 0.45 𝑆𝑃/𝐸 = 2.0

2018/12/21 Wuhan Wuhan The 4t he 4th China h China LHC Ph LHC Physics ysics Wo Workshop ( rkshop (ATHIC ATHIC 2018) 2018) 10

QCM in p-Pb collisions at 5.02 TeV

Song,Gou,Shao,Liang, Phys.Lett. B774(2017),516

2018/12/21 Wuhan Wuhan The 4t he 4th China h China LHC Ph LHC Physics ysics Wo Workshop ( rkshop (ATHIC ATHIC 2018) 2018) 11

QCM in pp collisions at 7 TeV

𝑞𝑈(GeV/c)

Minimum bias events

Gou,Shao,Song…,PRD96(2017), 094010

2018/12/21 Wuhan Wuhan The 4t he 4th China h China LHC Ph LHC Physics ysics Wo Workshop ( rkshop (ATHIC ATHIC 2018) 2018) 12

Zhang,Shao,Song,arXiv:1811.00975

QCM in pp collisions at 13 TeV

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Production of single-charm hadrons in pp and p-Pb collisions at LHC Equal-velocity combination of charm quark and light-flavor (anti)quarks Quark spectra at hadronization got from light-flavor hadrons consistent with pQCD calculations Parameters in the model: 𝑆𝑊/𝑄 = 1.5 𝑆𝑇3/𝑇1 = 1.5 thermal weights

Song, Li, Shao, Eur.Phys.J. C78 (2018) 344 Li, Shao,Song, PRC97(2018), 064915

2018/12/21 Wuhan Wuhan The 4t he 4th China h China LHC Ph LHC Physics ysics Wo Workshop ( rkshop (ATHIC ATHIC 2018) 2018) 14

D mesons of 𝒒𝑼 ≲8 GeV, = 𝒅 quark of 𝒒𝑼,𝒅 ≲ 𝟕 + l quark of 𝒒𝑼,𝒎 ≲ 𝟑 GeV

Song, Li, Shao, Eur.Phys.J. C78 (2018) 344 Li, Shao,Song, PRC97(2018), 064915

2018/12/21 Wuhan Wuhan The 4t he 4th China h China LHC Ph LHC Physics ysics Wo Workshop ( rkshop (ATHIC ATHIC 2018) 2018) 15

𝒒𝑼 dependence of charmed Baryon/Meson ratio

pp 7TeV p-Pb 5.02TeV p-Pb 5.02TeV 1.5<y<4

𝑞𝑈(GeV/c) 𝑞𝑈(GeV/c)

Song, Li, Shao, Eur.Phys.J. C78 (2018) 344 Li, Shao,Song, PRC97(2018), 064915

2018/12/21 Wuhan Wuhan The 4t he 4th China h China LHC Ph LHC Physics ysics Wo Workshop ( rkshop (ATHIC ATHIC 2018) 2018) 16

Summary

We show that in pp and p-Pb collisions at LHC energies ① data for 𝒒𝑼 spectra 𝛁 and 𝝔 exhibit the constituent quark number scaling property, ② Equal velocity combination of light-flavor quarks successfully explain 𝒒𝑼 spectra of light-flavor hadrons ③ Equal velocity combination of charm quark and light-flavor quark successfully explain data of D mesons and 𝚳𝐝 baryon,

• clear signals of quark combination mechanism at hadronization

Our results further suggest that

• constituent quark degrees of freedom (CQdof) play important role in the

production of hadrons in small quark/parton systems created in pp and p-Pb collisions at LHC.

• It should be incorporated in developing more sophisticated hadronization model

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Extraction of quark 𝒒𝑼 spectra from the data 𝑔

𝑟 𝑜 𝑞𝑈 = 𝒪 𝑟 𝑞𝑈 1 +

1 𝑜𝑟𝑑𝑟 𝑞𝑈

2 + 𝑛𝑟 2 − 𝑛𝑟 −𝑜𝑟

similar to AA collisions at RHIC and LHC energies! 20-40%

J.H. Chen, et al, PRC78,034907(08); RQ Wang, Shao, Song, PRC91,014909(15); Shao, Song, et al, PRC80,014909(09);

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𝝀𝑵𝒋 and 𝝀𝑪𝒋 can be well determined in QCM with a few parameters 𝜆𝐶𝑗 ≈ 𝐵𝑟1,𝑟2,𝑟3𝐷𝐶𝑗𝑂𝑗𝑢𝑓𝑠/15 𝑂𝑟

2

𝜆𝑁𝑗 ≈ 4𝐵𝑟1,ത

𝑟2𝐷𝑁𝑗/5 𝑂𝑟

where 𝑂𝑟 is total quark number. 𝐷𝐶𝑗 and 𝐷𝑁𝑗 are determined by parameters 𝑆𝐸/𝑃 and 𝑆𝑊/𝑄. 𝒪

𝑟1,𝑟2,𝑟3 and 𝒪 𝑟1,ത 𝑟2 are determined by quark 𝑞𝑈 spectrum

𝐵𝑟1,𝑟2,𝑟3∫ 𝑒𝑞𝑈 ෑ

𝑗=1 3

𝑔

𝑟𝑗 𝑜 𝑦𝑗𝑞𝑈 = 1

𝐵𝑟1,ത

𝑟2∫ 𝑒𝑞𝑈𝑔 𝑟1 𝑜 𝑦1𝑞𝑈 𝑔ത 𝑟2 𝑜 𝑦2𝑞𝑈 = 1

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We obtain 𝑔

𝐶𝑘 𝑞𝐶 = 𝜆𝐶𝑘𝑔 𝑟1 𝑦1𝑞𝐶 𝑔 𝑟2 𝑦2𝑞𝐶 𝑔 𝑟3 𝑦3𝑞𝐶

𝑔

𝑁𝑘 𝑞𝑁 = 𝜆𝑁𝑘𝑔 𝑟1 𝑦1𝑞𝑁 𝑔ത 𝑟2 𝑦2𝑞𝑁

which directly leads to 𝑔

Ω 3𝑞𝑈 = 𝜆Ω𝑔 𝑡3 𝑞𝑈

𝑔

𝜚 2𝑞𝑈 = 𝜆𝜚𝑔 𝑡2 𝑞𝑈

𝑔

Ω 1 3 3𝑞𝑈 = 𝜆𝜚,Ω𝑔 𝜚 1 2(2𝑞𝑈)

For combination of u(d) and s quark(s), equal velocity implies 𝒚𝒋 = 𝒏𝒋/ σ𝒌 𝒏𝒌, denote 𝒚𝒗

𝒚𝒕 = 𝒏𝒗 𝒏𝒕 = 𝒔

𝑔Ξ∗0 2 + 𝑠 𝑞𝑈 = 𝜆Ξ∗0 𝑔

𝑡2 𝑞𝑈 𝑔 𝑣 𝑠 𝑞𝑈

𝑔K∗0 1 + 𝑠 𝑞𝑈 = 𝜆K∗0 𝑔

𝑡 𝑞𝑈 𝑔 ത 𝑒 𝑠 𝑞𝑈

𝑔Ξ∗0( 2 + 𝑠 𝑞𝑈) 𝑔𝐿∗0 1 + 𝑠 𝑞𝑈 = 𝜆𝜚,𝐿∗,Ξ∗𝑔

𝜚 1 2 2𝑞𝑈

𝑠 ≈ 2/3 if we take 𝑛𝑡 = 500 − 550 MeV and 𝑛𝑣 = 𝑛𝑒 = 330 MeV.

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𝒒𝑼-integrated Yields of hadrons in pp, p-Pb and Pb-Pb collisions at LHC

SFL,SJ, et al, Phys.Rev.C95(2017) ,064911

Baryon/Meson yield ratios Hierarchy in yields among K, 𝚳, 𝚶 and 𝛁