Constituent quarks and multiparticle productionrhic.physics.wayne.edu/~voloshin/talks/201411_Journal... · 2014-11-21 · page 1 Journal club, WSU, November 18, 2014 S.A. Voloshin

Journal club, WSU, November 18, 2014 page S.A. Voloshin1

Constituent quarks and multiparticle production

Sergei A. Voloshin

Scales of QCD. Current, valence, and constituent quarksMultiparticle production in hA collisionsNucleon and quark participantsQuark coalescenceQuark participants and flow fluctuationsHadronization and PID correlations

Additive quark model – accuracy ~ 20%.

This talk: kind of hand waving …for the lack of good theory.

Usually models incorporate constituentquark picture to describe hadron static properties, but it could/should be important for dynamics of multiparticle production.

Not a review – far from mentioning all relevant references


Scales of hadronic physics

The first typical scale – 0.6-1.0 fm – typical hadron radius,(radius of confinement).

Additive quark model: (hadron spectroscopy, magnetic moments, etc.)

Levin – Ryskin (1965), Lipkin – Sheck (1966):

Experimentally ~ 1/1.6

Primordial kT in lepton pair and large pt production ~ 1-2 GeV

Shrinkage of the diffraction cone (== effective radius increases with energy):


Scales of QCD

Hadronic structure after Shuryak:Hadrons made of light quarks. The basic underlying phenomenon is breaking of chiral symmetry. Quark propagating on top of quark condensate , and thus obtaining “constituent quark”mass, being the main part of masses of all light hadrons.Vacuum == (as well as glue inside glueballs and hadrons) – superpositionof instantons, which provide the (non-local) interaction between quarks for chiral symmetry breaking. Valence quarks lead to suppression of instanton fluctuations

Radius of small size instantons – sets const. quark radius.

Mass of sigma meson

Quark model is motivated by QCD, but there is no theory at the moment.

Lattice: String size

Radius of confinement – sets hadron radius


Two scales of QCD. Multiple vacua.

Valence quarks lead to suppression of instanton fluctuations -- another way of thinking on constituent quark mass.

Defines the confinement radius, hadron size.

Defines the size of constituent quark, size of the “small” instantons

Instanton – classical solution describing tunneling between different QCD vaccua

Instanton fields leads to non-zero gluon condensate.Instanton induced quark interaction (attractive) leads to non-zero quark condensate,similar to Cooper pairing in a superconductor.

Quark propagating on top of the quark condensate obtains “constituent quark”mass, being the main part of masses of all light hadrons.

may be treated as dilute liquid

My distorted view of Shuryak’s picture

Journal club, WSU, November 18, 2014 page S.A. Voloshin

Hadron structute

5

u d s c b t


Mass splitting

6


Magnetic moments

7


Size, energy dependenceKovner - Wiedemann (hep-ph/0204277):Total cross section grows for two reasons:a) Increase in parton density (“darkness”) –described by “hard” Pomeron.b) Increase in radius (soft Pomeron) – asymptotically saturates

Froissart bound.

Kharzeev – Levin : instantons needed to limit gluon emission in 0.3 fm region

Bondarenko –Levin – Nyiri (hep-ph/0204156) –The size of quarks from double parton cross sectionand also from diffraction in DIS:

Typically:Scales: summary

Saturation – const. quark view.

Similar: string percolations (Braun, Ferreiro, Pajares, …)


qq center of mass. inelasticity coefficient.

9


Const. quarks and hA interactionsV.V. Anisovich, Yu.M. Shabelsky, V.M. Shekhter, Nucl.Phys. B133 (1978) 477

Spectators mesons/baryons at xF ~1/3and baryons at xF ~2/3

Also: for Kp reactions taking into account strange quark cross section


hA interactions, II

See also: B.A. Cole for the E910, “Constituent quarks and proton breakup in pA…Nucl. Phys. A661 (1999) 366c

Baryons at xF~2/3

Mesons at xF~1/3


ELSEVIER Nuclear Physics A661 (1999) 366c-369c

A

www.elsevier.nl/Iocate/npe

Cons t i tuen t Quarks and Pro ton Break-up in p-A Collisions at the AGS

B.A. Cole a for the E910 Collaboration: BNL-Columbia-FSU-Kent State-LBNL-LLNL-SUNY Stonybrook-Tennessee-Yonsei

aColumbia University, Nevis Labs, PO Box 137 Irvington, NY 10533

Results are presented from BNL experiment 910 on the centrality and target dependence of projectile stopping, A and K ° production, and ~r- production in p-A collisions. The data, taken together, suggest that the "stopping" of the baryon number and the stopping of the energy carried by the incident baryon in p-A collisions proceeds via different physical processes. We discuss a possible interpretation of the data in terms of constituent or valence quark interactions.

Proton-nucleus (p-A) collisions potentially provide a valuable tool for studying the initial conditions of heavy-ion collisions, particularly the initial nucleon multiple scattering and energy deposition processes. However, there is still much we don't understand about how a hadron interacts in a nucleus because most of the available p-A data is inclusive and thus insensitive to details of the dynamics. Experiment 910 [1] at the Brookhaven National Laboratory AGS accel- erator was designed to address this problem problem by providing semi-inclusive p-A measure- ments using a large-acceptance detector built around the EOS TPC [2]. Through a combination of large acceptance, good particle ID and high statistics E910 provides the worlds best data- set for studying the dynamics of stopping and secondary particle production in proton-nucleus interactions.

E910 was staged in the MPS (A1) secondary beam-line at the AGS and consisted of the EOS TPC, downstream drift-chambers, a segmented cherenkov counter, a time-of-flight wall, a scintillating-fiber multiplicity trigger counter, and upstream beam tracking and Cherenkov counters. E910 collected data using secondary beams of nominal momentum 6, 12, and 18 GeV/c and with Be, Cu, Au, and U targets. More details on the experiment and analysis techniques are provided in [3,4]. E910 characterizes the centrality of p-A using Ngrey , the multiplicity of "grey" tracks, which consist of protons in the momentum range 0.25 < p < 1.2 and deuterons with 0.5 < p < 2.4. These are detected in the TPC at polar angles < 65 ° and positively identified by dE/dx. The grey tracks result from the recoil shower induced by struck nucleons in the target so Ngrey is statistically related to u, the number of inelastic scatters of the projectile in the target nucleus. Different techniques for relating Ngrey to (v(Ngrey)) have been used in the past; E910 uses a variant of these techniques that is described and compared to other approaches in [3]

The first observable that we study as a function of Ngrey and (v(Ngrey)) is the amount of "stopping" of the projectile [4]. We quantify the stopping of the projectile by the average backward rapidity shift (Ay) of the highest-rapidity identified proton in the final state. A cut is applied to remove charge-exchange events in which an (unobserved) energetic neutron carries away most of the energy of the incident baryon. We plot in Fig. 1 (Ay) as a function of Ngrey and (/](Ngrey)) for 18 GeV/c p+Be, Cu, and Au collisions. Aside from a slight displacement of the Be data which likely results from systematic errors in the (v(Ngrey)) extraction, the (Ay) values for the three targets have the same dependence on (~(Ngrey)). We observe a backward rapidity

0375-9474/99/$ see front matter © 1999 Elsevier Science B.V. All fights reserved. PII S0375-9474(99)00474- l


Quark parton intranuclear cascade

Also: N.N. Nikolaev et al. CERN TH-2531, 1978


Cronin effect

Const quarks larger effect, + coalescence particle type dependence?

Interplay of gaussian and power law


Multiplicity in e+e- and pp

√s√seffBasile et al (1980-1984)

Mark D. Baker, PHOBOS, QM2002

Constituent quarkpicture:

Some excess inmultiplicity afterrescaling could be due to quark spectators


_pp

PHOBOS Au+Au

19.6 GeVpreliminary

130 GeV

200 GeVPRC 65 (2002) 061901R

Mark D. Baker, PHOBOS, QM2002

Centrality Dependence at Mid-rapidity

Often treated as:


Nucleon and quark participants vs. centralityS. Eremin, S.V., PRC 67, 064905( 2003)

We continue to use NN-part as a measure of centrality


dNch/dy vs. number of participants

Open symbols: our calculation of Npart

The ratio Nch/Nq-partslightly decreases withcentrality


Nucleon Scaling

2014%09%27( R.(Soltz(for(PHENIX(%(BES%II(Workshop(LBNL( 5(

partN0 100 200 300 400

)pa

rt /

(0.5

Nη

/dch

) [0-

5%] /

dN

part

/ (0

.5 N

η/d

chdN

0.4

0.6

0.8

1

1.2

2.76 TeV Pb+Pb (ALICE)200 GeV Au+Au130 GeV Au+Au62 GeV Au+Au39 GeV Au+Au27 GeV Au+Au19.6 GeV Au+Au7.7 GeV Au+Au

partN100 200 300 400

[y=0

])

part

/ (0

.5 N

η/d

chdN

0

2

4

6

8


The(BES%II(Challenge:(

• Dynamics(change(from(quark(to(nucleon(√sNN(<=(27(GeV(

•  To(find(CEP(signatures(amidst(changing(dynamics(

PRC.89.044905(

Multiplicity (quark) scaling

2014%09%27( R.(Soltz(for(PHENIX(%(BES%II(Workshop(LBNL( 4(

quark-partN0 500 1000

[y=0

])

quar

k-pa

rt /

(0.5

Nη

/dch

dN

0

1

2

3


ParKcipant(quark(scaling(works(well(√sNN=(62%200(GeV(

quark-partN0 500 1000

) [0-

5%]

quar

k-pa

rt /

(0.5

Nη

/dch

) / d

Nqu

ark-

part

/ (0

.5 N

η/d

chdN 0.8

1

1.2

1.4 2.76 TeV Pb+Pb (ALICE)200 GeV Au+Au130 GeV Au+Au62 GeV Au+Au39 GeV Au+Au27 GeV Au+Au19.6 GeV Au+Au7.7 GeV Au+Au


v2 vs Nch, U+U

20


Elliptic flow: MPC (D. Molnar and M. Gyulassy)v 2

HIJING x 80HIJING x 35HIJING x 13HIJING x 1hydro , sBC

Elastic scattering, Baseline (HIJING) parameters:

σgg= 3 mb, σtr= 1 mb;

1 gluon 1 charged particle;

dNglue/dy=210. opacity = σtr dN/dy =210 mb

Constituent quark plasma:

σtr up 2 - 3 (?) times,dN/dy up > 2 times, Could be close to the data…


AMPT+”string melting”

Zi-Wei Lin and C.M. Konucl-th/0108039

“String melting”: a) # of quarks in the system = # of quarks in the hadrons b) “quark” formation time


Quark coalescence

23

May 3 - 5, 2002STAR Analysis meeting - 13 S.A. Voloshin

K0 and elliptic flow

J. Fu, P. Sorensen

v2

pt

baryons

mesons

quarks

Quark coalescence?


Quark coalescence, QM2002

24

S.A. Voloshin Nantes, July 25, 2002 20

Identified particles, large pt.

Antiprotons K- + pi-

Protons K+ + pi+

Protons Pions+kaons

Lambdas K0

Preliminary

pt

STAR

Preliminary

v2(baryons) > v2(mesons) for pt > 2 GeV/c


S.A. Voloshin Nantes, July 25, 2002 21

Constituent quark model + coalescence

Side-notes: a) more particles produced via coalescence vs parton

fragmentation larger mean pt… b) higher baryon/meson ratio

Coalescence in the intermediate region (rare products):

v2

pt

baryons

mesons

quarks

v2(��,��)

v2(pbar)

v2(�+,�+) v2(proton)

Preliminary

- What is the centrality dependence of the effect?

coalescence fragmentation

Low pt quarks High pt quarks


Quark coalescence and elliptic flow

Coalescence in the intermediate region (rare products)can be described by:

S.V. Nucl. Phys. A715 (2003) 739cMolnar, S.V. PRL 91:092301, 2003

There could be also quark typedependence, mass dependencecould be similar to “hydro” type


Elliptic flow of Kshort and Λ

v2 appears to saturate ~ 0.16 for KS and ~ 0.24 for Λ at different transverse momenta

P. Sorensen for STAR


For coalescence of co-moving const. quarks: hadron v2(pT) equals parton v2 at pT/n, scaled by the number of quarks (n).

STAR preliminary (Au+Au; 200 GeV; |y|<1.0)

Constituent quark v2(pt)?

Should the value of v2~ 0.08 be compared to Shuryak’ssurface emission picture?


Recent data

Perfect scaling for all measured hadrons,some deviation for pions (from ρ decays)


pTmeson≈2·pT

parton?

• pTbaryon≈3·pT

parton?

The saturation of v2 and the drop of RAA seem to be correlated.

RAA and v2: correlated?

P. Sorensen for STAR


Particle yields


Elliptic flow due to jet quenching

Gyulassy, Vitev & Wang, PRL 86 (2001) 2537

cylindrical geom.

Wood-Saxon

R. Snellings, A. Poskanzer, S.V., nucl-ex/9904003


Elliptic flow due to jet quenching (?)

STAR PreliminaryAu+Au, 200 GeV

Hard shell

Hard sphere

Woods-Saxon

Hard shell == box density profile (+) extreme quenchingHard sphere == -”- (+) realistic quenchingWoods-Saxon == WS density profile (+) realistic quenching

E. Shuryak, nucl-th/0112042


Constutuent quarks and flow fluctuations

R. Snellings

Surprisingly, constituent quark approach gives very reasonable result


Hadronization. PID correlations.

Gluons with typical momenta of 1-2 GeV form constituent quarks.Constituent quarks, if possible, recombine into hadrons orfurther fragment.

Constituent quarks created in this manner are subject to local conservationof charge(s) and momentum.

Typical scale of (conserved charge) correlations in rapidity ~ ln(s0/mt

2) ~1-2 units.

Scott Pratt: two wave quark production. Can we see it?


EXTRA SLIDES

36


Conclusions

Dependence of baryon/meson yields/elliptic flow on centrality –The picture should depend on the quark density which depends bothon pt and centrality.

Charge correlations: high pt hadron should be correlated with hadron of approximately half the momentum .

Etc.

what to look for?

Constituent quark phase could be a necessary and important part of the hadronization picture. We should keep it in mind.

HIT, LBNL, May 27, 2008 S.A. Voloshin 38

Multiple vacua. IIClassical vacuum zero E, B fields Ai fields are ”pure gauge”

Example, SU(2), nW=1

Instanton solution was found byBelavin, Polyakov, Tyupkin, and Shvarts.Name, interpretation and more by ‘t Hooft

Edm of the neutron. Edm(Q) in lattice


v2/n, different centralities

The agreement is worst for the most central collisions – non-flow effects?


v2 max due to jet quenching (absorption)

E. Shuryak, nucl-th/0112042

v 2

impact parameter (fm)

STAR

Observed anisotropy at high pt is close to maximum possible due to the jet quenching

Realistic nuclear density – effect drops about 2 times, but coalescence could bring it back

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Constituent quarks and multiparticle productionrhic.physics.wayne.edu/~voloshin/talks/201411_Journal... · 2014-11-21 · page 1 Journal club, WSU, November 18, 2014 S.A. Voloshin