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New results on Coulomb effects in meson production in relativistic heavy ion collisions Andrzej Rybicki H. Niewodniczaski Institute of Nuclear Physics Polish Academy of Sciences I . S p u t o w s k a 1) Introduction 2) Azimuthal

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Andrzej Rybicki, MESON 2014, Kraków, 29 May – 3 June 2014

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New results on Coulomb effects in meson production in relativistic heavy ion collisions

Andrzej Rybicki

  • H. Niewodniczański Institute of Nuclear Physics

Polish Academy of Sciences

I . S p u t

  • w

s k a

work in collaboration with Antoni Szczurek Mariola Kłusek-Gawenda

1) Introduction 2) Azimuthal anisotropies 3) Conclusions

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Andrzej Rybicki, MESON 2014, Kraków, 29 May – 3 June 2014

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1) Introduction

I . S p u t

  • w

s k a

Heavy ion collisions: (Pb+Pb, Au+Au) √sNN= 9 - 17 GeV

_

participant zone spectator system produced particles (π mesons)

  • Coulomb effects modify the spectra of charged mesons.

A.R., A. Szczurek, Phys. Rev. C75 (2007) 054903, A.R., Acta Phys. Polon. B42 (2011) 867

  • Do they influence the

azimuthal correlations?

( YES )

  • Can we gain new

information on the dynamical evolution of the participant system? ( YES )

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Andrzej Rybicki, MESON 2014, Kraków, 29 May – 3 June 2014

3

2) Azimuthal anisotropies

See also:

  • A. R. and A. Szczurek, Phys. Rev. C87 (2013) 054909.

Technical details: A.R. and A. Szczurek, Phys. Rev. C75 (2007) 054903.

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Andrzej Rybicki, MESON 2014, Kraków, 29 May – 3 June 2014

4

Pb+Pb peripheral, sqrt(sNN)=17.3 GeV

tE= 0

Original plot taken from:

  • D. Derendarz,

Kraków Epiphany Conference, Jan 2014

  • Directed flow: v1 ≡ < cos( φ−ΨRP ) >
  • Reflects sidewards collective motion.
  • What is the role of Coulomb effects ?

NA49, Phys.Rev. C68 (2003) 034903

Summed charged pions

√sNN= 8.8 GeV √sNN=17.3 GeV

Pb+Pb peripheral

_ _

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Andrzej Rybicki, MESON 2014, Kraków, 29 May – 3 June 2014

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  • Directed flow: v1 ≡ < cos( φ−ΨRP ) >
  • Reflects sidewards collective motion.
  • Pure electromagnetic effect below.

t = tE

pure EM effect :

Pb+Pb peripheral, √sNN=17.3 GeV

0 < pT < 1 GeV/c

_

t = tE dE

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Andrzej Rybicki, MESON 2014, Kraków, 29 May – 3 June 2014

6

  • Directed flow: v1 ≡ < cos( φ−ΨRP ) >
  • Reflects sidewards collective motion.
  • Pure electromagnetic effect below.

Pb+Pb peripheral, √sNN=17.3 GeV

0 < pT < 1 GeV/c

t = tE dE

data points from:

  • H. Schlagheck (WA98 Collaboration),
  • Nucl. Phys. A 663, 725 (2000).

WA98

_

pure EM effect is comparable to exp. data

dE < 1 fm

pure EM effect :

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Andrzej Rybicki, MESON 2014, Kraków, 29 May – 3 June 2014

7

2.1) Azimuthal anisotropies – Part II

See also:

  • A. R. and A. Szczurek, arXiv:1405.6860 [nucl-th],

May 27, 2014

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Andrzej Rybicki, MESON 2014, Kraków, 29 May – 3 June 2014

8

We assume: We know: This gives:

  • L. Adamczyk et al. (STAR Collaboration),
  • Phys. Rev. Lett. 112, 162301 (2014)

√sNN = 7.7 GeV _

Original plot taken from:

  • D. Derendarz,

Kraków Epiphany Conference, Jan 2014

v1 ≡ < cos( φ−ΨRP ) >

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Andrzej Rybicki, MESON 2014, Kraków, 29 May – 3 June 2014

9

Dependence on emission time

y/ybeam

dE ≈ 3 fm

STAR

t = tE t = tE dE

dE≈ 0.5 fm dE≈ 1 fm dE ≈ 2 fm dE ≈ 3 fm dE ≈ 5 fm

dE= 0 fm dE= 0 fm

dE≈ 0.5 fm dE≈ 1 fm d E ≈ 2 fm dE ≈ 3 fm dE ≈ 5 fm

Strong dependence on

dE (again).

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Andrzej Rybicki, MESON 2014, Kraków, 29 May – 3 June 2014

10

Dependence on emission time

y/ybeam y/ybeam

dE ≈ 3 fm dE ≈ 3 fm

STAR STAR dE≈ 0.5 fm dE≈ 1 fm dE ≈ 2 fm dE ≈ 3 fm dE ≈ 5 fm

dE= 0 fm dE= 0 fm

dE≈ 0.5 fm dE≈ 1 fm d E ≈ 2 fm dE ≈ 3 fm dE ≈ 5 fm

Strong dependence on

dE (again).

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Andrzej Rybicki, MESON 2014, Kraków, 29 May – 3 June 2014

11

dE

dE = τf ( βspectcosh(y) – sinh(y) )

τf = 5.08 fm/c

Rapidity dependence of pion emission

dE ≈ 3 fm ( STAR, small y ) dE < 1 fm ( WA98, y ≈ ybeam )

y=0.5

y/ybeam y/ybeam

dE ≈ 3 fm dE ≈ 3 fm

STAR

  • dE decreases with increasing pion rapidity
  • reflects the longitudinal evolution of the system

STAR

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Andrzej Rybicki, MESON 2014, Kraków, 29 May – 3 June 2014

12

3) Conclusions

 In heavy ion collisions, Coulomb fields are generated by charged

spectators.

 These Coulomb fields not only modify the spectra of charged mesons

but also lead to azimuthal distortions.

 These effects are sensitive to the distance dE between the pion

emission site and the spectator(s).

 dE decreases with increasing pion rapidity, reflecting the

longitudinal evolution of the system.

 This proves that the spectator-induced Coulomb field constitutes

a new source of information on the space-time properties of the system created in the heavy ion collision, completely independent from other sources such as pion interferometry.

Thank you!

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Andrzej Rybicki, MESON 2014, Kraków, 29 May – 3 June 2014

13

Acknowledgments.

This work was supported by the Polish National Science Centre (on the basis of decision no. DEC-2011/03/B/ST2/02634).

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Andrzej Rybicki, MESON 2014, Kraków, 29 May – 3 June 2014

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Extra slides

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Andrzej Rybicki, MESON 2014, Kraków, 29 May – 3 June 2014

15

A.R., A.Szczurek, PRC 75, 2007, A.R., PoS (EPS-HEP2009)

Pb+Pb

  • A. R. and A. Szczurek,
  • Phys. Rev. C75 (2007)

054903

  • A. R.,

Acta Phys. Polon. B42 (2011) 867

xF

pL pL

MAX NA49 preliminary

( c.m.s. )

Coulomb Repulsion ( for π+ ) Attraction ( for π− )

 Pb+Pb peripheral, √sNN=17.3 GeV  Minimum at xF= 0.15 = mπ/mp

_

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Andrzej Rybicki, MESON 2014, Kraków, 29 May – 3 June 2014

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A.R., A.Szczurek, PRC 75, 2007, A.R., PoS (EPS-HEP2009)

Pb+Pb

  • A. R. and A. Szczurek,
  • Phys. Rev. C75 (2007)

054903

  • A. R.,

Acta Phys. Polon. B42 (2011) 867

xF

pL pL

MAX

Monte Carlo

NA49 preliminary

d E = 0 fm dE = 1 fm d E = 0.5 fm d E = 1.5 fm

( c.m.s. )

xF

t = tE dE

Best description for: 50% * (dE = 0.5 fm) + 50% * (dE = 1 fm)

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Andrzej Rybicki, MESON 2014, Kraków, 29 May – 3 June 2014

17

A.R., A.Szczurek, PRC 75, 2007, A.R., PoS (EPS-HEP2009)

Pb+Pb

  • A. R. and A. Szczurek,
  • Phys. Rev. C75 (2007)

054903

  • A. R.,

Acta Phys. Polon. B42 (2011) 867

xF

pL pL

MAX

Monte Carlo

NA49 preliminary

d E = 0 fm dE = 1 fm d E = 0.5 fm d E = 1.5 fm

( c.m.s. )

xF

t = tE dE

Best description for: 50% * (dE = 0.5 fm) + 50% * (dE = 1 fm)

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Andrzej Rybicki, MESON 2014, Kraków, 29 May – 3 June 2014

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NA49 preliminary

Pb+Pb

Monte-Carlo

A . R . , A c t a P h y s . P

  • l

. B 4 2 , 2 1 1

t = tE

A.R., Acta Phys. Pol. B42, 2011 A.R., A.Szczurek, PRC 75, 2007

pT =

325 MeV/c 175 MeV/c 125 MeV/c 75 MeV/c 25 MeV/c

t E = 0 fm/c t E = 1 fm/c t E = 0.5 fm/c

xF

  • 1 -0.5 0 0.5 1
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Andrzej Rybicki, MESON 2014, Kraków, 29 May – 3 June 2014

19

d E = 1 fm

  • A. Rybicki, habilitation thesis,

Report no. 2040/PH,

  • H. Niewodniczański Institute of Nuclear

Physics, Polish Academy of Sciences, Kraków, 2010.

Source-size dependence

  • f charged pion ratios (1)
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Andrzej Rybicki, MESON 2014, Kraków, 29 May – 3 June 2014

20

d E = 0 fm

  • A. R. and A. Szczurek,
  • Phys. Rev. C75 (2007) 054903.

Source-size dependence

  • f charged pion ratios (2)
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Andrzej Rybicki, MESON 2014, Kraków, 29 May – 3 June 2014

21

precise NA49 data

  • n N+N collisions
  • C. Alt et al.,
  • Eur. Phys. J. C45

(2006) 343.

  • the collision takes place at a given impact parameter b.
  • the spectator systems = uniform spheres (in their rest frames).
  • the pion emission - single point in space. The emission time tE

is a free parameter.

  • the initial distribution of the emitted pions is assumed similar to N+N

collisions (scaled). Full azimuthal symmetry is assumed.

  • charged pions are traced in the spectator EM field.

t = tE

Nwounded= 60

includes retardation, etc.

Monte Carlo,

HFB,

Mizutori et al.

  • Phys. Rev. C 61,

(2000) 044326.

typically 42,000,000 pions.

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Andrzej Rybicki, MESON 2014, Kraków, 29 May – 3 June 2014

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Dependence on emission time

Dependence on initial conditions.

t = tE

Pb+Pb peripheral, √sNN=17.3 GeV

0 < pT < 1 GeV/c

_

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Andrzej Rybicki, MESON 2014, Kraków, 29 May – 3 June 2014

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Dependence on emission time

t = tE

Pb+Pb peripheral, √sNN=17.3 GeV

0 < pT < 1 GeV/c

_

pT=

75 125 175 MeV/c

dE

Dependence on transverse momentum

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Andrzej Rybicki, MESON 2014, Kraków, 29 May – 3 June 2014

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Green solid – only projectile spectator Blue solid – only target spectator Dots - direct addition: Red solid – both spectators v1(projectile) + v1(target) = v1(both spectators)

Pb+Pb peripheral, √sNN=17.3 GeV

0 < pT < 1 GeV/c

_

tE = 0 tE = 0

Side remark on the two spectators

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Andrzej Rybicki, MESON 2014, Kraków, 29 May – 3 June 2014

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NA49 / NA61

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Andrzej Rybicki, MESON 2014, Kraków, 29 May – 3 June 2014

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dE ≈ 0, 0.5, 1 fm

Experiments (data exists or could come): WA98 STAR NICA → research proposal, Dec 2012

y/ybeam

NA49, Phys.Rev. C68 (2003) 034903

WA98 Pb+Pb Au+Au pions

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Andrzej Rybicki, MESON 2014, Kraków, 29 May – 3 June 2014

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dE ≈ 0, 0.5, 1 fm

Experiments (data exists or could come): WA98 STAR NICA → research proposal, Dec 2012

y/ybeam

NA49, Phys.Rev. C68 (2003) 034903

pions WA98 Pb+Pb Au+Au