Multiparticle production in nuclear collisions using

Aditya Nath Mishra! Indian Institute of Technology Indore, INDIA!

ISMD2014 (Italy, September 8-12, 2014)!!

Multiparticle production in nuclear collisions using effective energy approach!

A.N. Mishra, R. Sahoo, E.K.G. Sarkisyan, A.S. Sakharov !arXiv:1405.2819 !

Motivation Bulk observables - mean multiplicity and rapidity densities - control parameters of the formation and evolution of the collision initial state !!Extensively studied in heavy-ion collisions at RHIC !

Aditya Nath Mishra ISMD2014, Italy 1

Motivation Bulk observables - mean multiplicity and rapidity densities - control parameters of the formation and evolution of the collision initial state !!Extensively studied in heavy-ion collisions at RHIC !Similarities with e+e- and pp data: !universality in multihadron production !

30% of a spectator energy?



pp multiplicity data to !be scaled !






pp midrapidity density does not obey a similar scaling !




Not the same scaling for both variables and for different types of interactions!


pp midrapidity density does not obey a similar scaling !


J.F. Grosse-‐Oetringhaus and K. Reygers (2010): K=1/3, n0~2

Constituent Quark Framework No nucleon participant dependence as soon as calculated in the constituent quark framework!

R.Sahoo, A.N.M. (2014)!


Nucleon part.

Quark part.

Nucleon Participant: Open vs solid symbols: hijing vs overlap model!Quark Participant: Open vs solid symbols: different σpp!!

Constituent Quark Framework No nucleon participant dependence as soon as calculated in the constituent quark framework!!AA centrality data are similar to NSD measurements!

R.Sahoo, A.N.M. (2014)!

Aditya Nath Mishra ISMD2014, Italy 2 R. Nouicer (2007), PHOBOS data!

Nucleon part.

Quark part.

pp/p̄p

Nucleon part.

Quark part.

Constituent Quark Framework No nucleon participant dependence as soon as calculated in the constituent quark framework!!AA centrality data are similar to NSD measurements!!Quark degrees of freedom seem to !play a role, not the nucleon ones!!

R.Sahoo, A.N.M. (2014)!

Aditya Nath Mishra ISMD2014, Italy 2 R. Nouicer (2007), PHOBOS data!

Nucleon part.

Quark part.

pp/p̄p

Nucleon part.

Quark part.

Energy Scaling vs. Types of Collisions ü  e+e- (structureless particles) annihilation - the total interaction energy

is deposited in the initial state !

ü  pp (superposition of three pairs of constituents) collision - only the energy of the interacting single quark pair is deposited in the initial state !

ü  Both multiplicity and midrapidity density should be similar in pp at c.m. energy √spp and e+e- at c.m. energy √see≈ √spp/3 !


Energy Scaling vs. Types of Collisions ü  e+e- (structureless particles) annihilation - the total interaction energy

is deposited in the initial state !

ü  pp (superposition of three pairs of constituents) collision - only the energy of the interacting single quark pair is deposited in the initial state !

ü  Both multiplicity and midrapidity density should be similar in pp at c.m. energy √spp and e+e- at c.m. energy √see≈ √spp/3 !

ü  Head-on heavy ion collisions: all three quarks participate nearly simultaneously and deposit their energy coherently into initial state!

ü  Both multiplicity and midrapidity density should be similar in pp at c.m. energy √spp and head-on AA at c.m. energy √sNN ≈ √spp/3 !

!


E. Sarkisyan & A. Sakharov (2004) : dissipaBng energy parBcipants

Hydrodynamics of Collisions Ø  Two head-on colliding Lorentz-contracted particles stop within

the overlapped zone !v Formation of fully thermalized initial state at the collision moment!v  The decay (expansion) of the initial state is governed by relativistic ! hydrodynamics - Landau model (1953)!

4 ISMD2014, Italy Aditya Nath Mishra



Steinberg, nucl-‐ex/0405022





BRAHMS, nucl-‐ex/0410003

2Nch

Npart

exp(�y

2/2L)p2⇡L

, L = ln

ps

2m





BRAHMS, nucl-‐ex/0410003

2Nch

Npart

exp(�y

2/2L)p2⇡L

, L = ln

ps

2m


•  The production of secondaries is defined by the energy deposited ! into the initial state!

Hydrodynamics & Energy Scaling vs Data from Landau Hydrodynamics !

⇢(0) = ⇢pp(0)2Nch

NpartNppch

rLpp

LNNL = ln

ps

2m



⇢(0) = ⇢pp(0)2Nch

NpartNppch

rLpp

LNNL = ln

ps

2m

Landau Hydrodynamics+ Constituent Quark approach ⇢(0) = ⇢pp(0)

2Nch

NpartNppch

s1� 4 ln3

ln(4m2p/sNN)



⇢(0) = ⇢pp(0)2Nch

NpartNppch

rLpp

LNNL = ln

ps

2m


2Nch

NpartNppch

s1� 4 ln3

ln(4m2p/sNN)

ü  Nuclear data both on midrapidity density and mean multiplicity energy dependence well reproduced up to top RHIC energy!

E.K.G. Sarkisyan, A.S. Sakharov (2010)



⇢(0) = ⇢pp(0)2Nch

NpartNppch

rLpp

LNNL = ln

ps

2m


2Nch

NpartNppch

s1� 4 ln3

ln(4m2p/sNN)


ü  pp data at the LHC energy of 2-7 TeV well predicted!


Aditya Nath Mishra ISMD2014, Italy 5 CMS conf. reports

pp


⇢(0) = ⇢pp(0)2Nch

NpartNppch

rLpp

LNNL = ln

ps

2m


2Nch

NpartNppch

s1� 4 ln3

ln(4m2p/sNN)


ü  pp data at the LHC energy of 2-7 TeV well predicted!

ü  Heavy-ion collisions at the LHC indicate a transition to a possibly new regime with more degrees of freedom !


Aditya Nath Mishra ISMD2014, Italy 5 CMS conf. reports

pp

Effective Energy: Effective energy can be calculated as following:!

! !!!Here α is centrality percentile. !e.g. For 0-5% central collision α = 0.025!!

✏NN =psNN(1 � ↵)

Hydrodynamics and Effective Energy


Hydrodynamics and Effective Energy

⇢(0) = ⇢pp(0)2Nch

NpartNppch

s

1� 2 ln3

ln(2mp/✏NN)

✏NN =pspp/3


Effective Energy: Effective energy can be calculated as following:!

! !!!Here α is centrality percentile. !e.g. For 0-5% central collision α = 0.025!!

✏NN =psNN(1 � ↵)

Charged Particle Mid-rapidity Density

2

4

6

8

10

12

0 100 200 300 400Npart

l(0)

= 2

dN ch

/dd| d

=0 /

N part

CMS 2.76 TeVPHOBOS 200 GeV × 2.12PHOBOS 200 GeVPHOBOS 130 GeVPHOBOS 62.4 GeVPHOBOS 19.6 GeVCQM + Landau, pp-basedEffective energy dissip. model

Effective energy dissip. modelprediction for 3s<NN = 5.52 TeVCMS 2.76 TeV × 1.43

Upto top RHIC energy the data show slight increase as centrality decreases!!LHC data has monotonic increasing behavior!



2

4

6

8

10

12

0 100 200 300 400Npart

l(0)

= 2

dN ch

/dd| d

=0 /

N part



Upto top RHIC energy the data show slight increase as centrality decreases!!LHC data has monotonic increasing behavior!!CQM+Landau calculations have a very good agreement with data!


Nch is calculated at √sNN = εNN!ρpp(0) and Npp

ch are calculated at !√spp = 3εNN!


2

4

6

8

10

12

0 100 200 300 400Npart

l(0)

= 2

dN ch

/dd| d

=0 /

N part



Upto top RHIC energy the data show slight increase as centrality decreases!!LHC data has monotonic increasing behavior!!CQM+Landau calculations have a very good agreement with data!!Effective energy dissipation (red line of the fit to head-on c o l l i s i o n d a t a e n e r g y dependence [next slide]) also explains data and gives predictions at √sNN= 5.52 TeV!!

Nch is calculated at √sNN = εNN!ρpp(0) and Npp

ch are calculated at !√spp = 3εNN! Aditya Nath Mishra ISMD2014, Italy 7

Charged Particle Mid-rapidity Density ü  Similarity in all the data from

peripheral to the most central ones follow the same energy behavior!

2

4

6

8

10

12

14

1 10 10 2 10 3

3s<

NN , ¡NN [GeV]

l(0)

= 2

dN ch

/dd

| d=0

/ N pa

rt

AA central collisionsLHC data

ALICEATLASCMS

RHIC AuAu dataBRAHMSPHENIX

PHOBOS STAR

SPS dataNA45NA49

AGS dataE802/917

GSI dataFOPI

hybrid fit: log(s) + power-lawpower-law fitlog(s) fit up to RHIC data

Energy dissipation model calculationfor AA centrality data at ¡NN

CMSPHOBOSSTAR

Fits to weighted LHC and RHIC dataLHC: ALICE, ATLAS, CMSRHIC: PHENIX, PHOBOS, STAR

hybrid fit: log(s) + power-lawpower-law fit

Prediction for AA at 3s<NN = 5.52 TeV




ü  Hybrid fit to both the most central (head-on)and centrality data sets are close enough!

!

2

4

6

8

10

12

14

1 10 10 2 10 3

3s<

NN , ¡NN [GeV]

l(0)

= 2

dN ch

/dd

| d=0

/ N pa

rt


ALICEATLASCMS


PHOBOS STAR

SPS dataNA45NA49

AGS dataE802/917

GSI dataFOPI



CMSPHOBOSSTAR








!ü  Model well reproduces the

data under the assumption of the effective energy deriving the multi-particle production process!

!ü  The combined data indicate

possible transition to a new regime at √sNN=0.5-1.0 TeV!

2

4

6

8

10

12

14

1 10 10 2 10 3

3s<

NN , ¡NN [GeV]

l(0)

= 2

dN ch

/dd

| d=0

/ N pa

rt


ALICEATLASCMS


PHOBOS STAR

SPS dataNA45NA49

AGS dataE802/917

GSI dataFOPI



CMSPHOBOSSTAR










!ü  The combined data indicate

possible transition to a new regime at √sNN=0.5-1.0 TeV!

2

4

6

8

10

12

14

1 10 10 2 10 3

3s<

NN , ¡NN [GeV]

l(0)

= 2

dN ch

/dd

| d=0

/ N pa

rt


ALICEATLASCMS


PHOBOS STAR

SPS dataNA45NA49

AGS dataE802/917

GSI dataFOPI



CMSPHOBOSSTAR




PredicYon for charged parYcle mid-‐rapidity density for Pb+Pb collisions at √sNN = 5.52 TeV is about 12.0 (within 10% uncertainty)


Charged Particle Mid-rapidity Density ü  Hybrid fit to both the central

and centrality data sets are close enough!



ü  Similarity in all the data from peripheral to the most central ones follow the same energy behavior!

ü  The combined data indicate possible transition to a new regime at √sNN=0.5-1.0 TeV!

PredicYon for charged parYcle mid-‐rapidity density for Pb+Pb collisions at √sNN = 5.52 TeV is about 12.0 (within 10% uncertainty)


2

4

6

8

10

12

0 100 200 300 400Npart

l(0)

= 2

dNch

/dd|

d=0 / N

part



2

4

6

8

10

12

14

1 10 10 2 10 3

3s<

NN , ¡NN [GeV]

l(0)

= 2

dN ch

/dd

| d=0

/ N pa

rt


ALICEATLASCMS


PHOBOS STAR

SPS dataNA45NA49

AGS dataE802/917

GSI dataFOPI



CMSPHOBOSSTAR




ET in Constituent Quark Framework ü  Similar to the midrapidity

density ET measurements show independence of centrality as soon as recalculated in the constituent quark frame!

PHENIX Collab. (2014)!

Aditya Nath Mishra ISMD2014, Italy

Quark part.

!

R.Sahoo, A.N.M. (2014)!

9

Quark part.

Nucleon part.

ET in Constituent Quark Framework ü  Similar to the midrapidity

density ET measurements show independence of centrality as soon as recalculated in the constituent quark frame!

PHENIX Collab. (2014)!

Aditya Nath Mishra ISMD2014, Italy

Quark part.

! !

R.Sahoo, A.N.M. (2014)!

9

Quark part.

Nucleon part.

ü  Indicates an importance of constituent quark degrees of freedom, therefore the effective energy of participants deriving particle production!

0

2

4

6

8

10

12

14

16

1 10 10 2 10 3

3s<

NN , ¡NN [GeV]

l T(0) =

2 dE

T /dd|

d=0 / N

part [

GeV] AA central collisions

LHC dataCMS

RHIC dataPHENIXSTAR

SPS dataNA49WA98

AGS dataE802/917

GSI dataFOPI

hybrid fit: log(s) + power-lawpower-law fitlog(s) fit up to RHIC data (PHENIX)


CMSPHENIX

Fits to weighted CMS, PHENIX, STAR datahybrid fit: log(s) + power-lawpower-law fit


ü  Centrality data are shown as a function of the effective c.m. energy εNN!

Transverse Energy Mid-rapidity Density


0

2

4

6

8

10

12

14

16

1 10 10 2 10 3

3s<

NN , ¡NN [GeV]

l T(0) =

2 dE

T /dd|

d=0 / N

part [


LHC dataCMS

RHIC dataPHENIXSTAR

SPS dataNA49WA98

AGS dataE802/917

GSI dataFOPI



CMSPHENIX




!ü  Centrality data follow well the

d a t a f r o m t h e c e n t r a l collisions.!

ü  Hybrid fits are amazingly close to each other for the entire energy range.!



0

2

4

6

8

10

12

14

16

1 10 10 2 10 3

3s<

NN , ¡NN [GeV]

l T(0) =

2 dE

T /dd|

d=0 / N

part [


LHC dataCMS

RHIC dataPHENIXSTAR

SPS dataNA49WA98

AGS dataE802/917

GSI dataFOPI



CMSPHENIX







!Effective energy approach provides a good description of the ET production in heavy-ion collisions!



0

2

4

6

8

10

12

14

16

1 10 10 2 10 3

3s<

NN , ¡NN [GeV]

l T(0) =

2 dE

T /dd|

d=0 / N

part [


LHC dataCMS

RHIC dataPHENIXSTAR

SPS dataNA49WA98

AGS dataE802/917

GSI dataFOPI



CMSPHENIX








v  LHC data depart from the linear-log in the region of √sNN ≃ 0.5 − 1.0 TeV!

v  Possibly transition to a new r e g i m e i n h e a v y - i o n collisions!



0

2

4

6

8

10

12

14

16

1 10 10 2 10 3

3s<

NN , ¡NN [GeV]

l T(0) =

2 dE

T /dd|

d=0 / N

part [


LHC dataCMS

RHIC dataPHENIXSTAR

SPS dataNA49WA98

AGS dataE802/917

GSI dataFOPI



CMSPHENIX












PredicYon for the transverse energy mid-‐rapidity density for Pb+Pb collisions at √sNN = 5.52 TeV is about 16.9 (within 10% uncertainty)

0

2

4

6

8

10

12

14

16

1 10 10 2 10 3

3s<

NN , ¡NN [GeV]

l T(0) =

2 dE

T /dd|

d=0 / N

part [


LHC dataCMS

RHIC dataPHENIXSTAR

SPS dataNA49WA98

AGS dataE802/917

GSI dataFOPI



CMSPHENIX












PredicYon for the transverse energy mid-‐rapidity density for Pb+Pb collisions at √sNN = 5.52 TeV is about 16.9 (within 10% uncertainty)

2

4

6

8

10

12

14

1 10 10 2 10 3

3s<

NN , ¡NN [GeV]l(

0) =

2 d

Nch

/dd

| d=0

/ N

part


ALICEATLASCMS


PHOBOS STAR

SPS dataNA45NA49

AGS dataE802/917

GSI dataFOPI



CMSPHOBOSSTAR




2

4

6

8

10

12

14

16

0 100 200 300 400Npart

l T(0

) = 2

dE T

/dd| d

=0 /N

part

[G

eV]

CMS 2.76 TeVPHENIX 200 GeV × 3.07PHENIX 200 GeVPHENIX 130 GeVPHENIX 62.4 GeVPHENIX 19.6 GeVEffective energy dissip. model


ü  LHC data shows faster decrease with centrality as compared to RHIC data (in contrast to midrapidity data)!



2

4

6

8

10

12

14

16

0 100 200 300 400Npart

l T(0

) = 2

dE T

/dd| d

=0 /N

part

[G

eV]




ü  Effective energy approach very well explains the experimental data!

ü  Agreement is even better than for the charge particle midrapidity density!



2

4

6

8

10

12

14

16

0 100 200 300 400Npart

l T(0

) = 2

dE T

/dd| d

=0 /N

part

[G

eV]




ü  Effective energy approach very well explains the experimental data!

ü  Agreement is even better than for the charge particle midrapidity density!



Predictions for the future heavy-ion collisions at √sNN = 5.52 TeV given!

Summary ü  Centrality and c.m. energy dependence of bulk observables (charged

particle and transverse energy midrapidity density) are analyzed for all available energies!

ü  Universality in particle production process is obtained based on the model considering dissipating energy available at the early stage of collision from interacting participants depending upon their type!

ü  Bulk observables in heavy-ion collisions are well reproduced from those in pp collisions, treated within constituent quark model and Landau hydrodynamics!

ü  Available measurements upto LHC energies agree well with the model expectations. A possible transition to a new regime at √sNN = 0.5 – 1.0 TeV is indicated, the measurements are welcome!

ü  Prediction for the foreseen LHC energy at 5.52 TeV Pb+Pb collisions is made!Aditya Nath Mishra ISMD2014, Italy 12

Thank you

Documents

Multiparticle production in nuclear collisions using