Symposium on Exciting Physics: Quarks and gluons / atomic nuclei / biological systems / networks. Makutsi Safari Farm, South Africa November 16, 2011

Transcription

1 Symposium on Exciting Physics: Quarks and gluons / atomic nuclei / biological systems / networks. Makutsi Safari Farm, South Africa November 16, 2011

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3 Photons and dileptons are important probes for the deconfined hadronic matter, commonly called Quark-Gluon-Plasma (QGP). Unlike the strongly interacting hadrons, which can give information only about the last scattering surface, electromagnetically interacting photons and dileptons give information about the matter at very early times. 3

4 PMD in WA98 Experiment 4

5 Brookhaven National Laboratory, New York PHOBOS PHENIX 1 km RHIC BRAHMS PHENIX BARC & BHU h STAR STAR STAR IOP Bhubaneswar Panjab U., Chandigarh Rajasthan U., Jaipur Jammu U., Jammu VECC, Kolkata 5 5

6 LHC: Photon Multiplicity Detector IOP Bhubaneswar Panjab U. Chandigarh Rajasthan U. Jaipur Jammu U. Jammu VECC Kolkata Muon Arm Project SINP Kolkata AMU Aligarh CERN, Geneva 9km LHC SPS WA93 & SPS: IOP Bhubaneswar Panjab U., Chandigarh Rajasthan U., Jaipur Jammu U., Jammu VECC, Kolkata 6 6

7 ALICE Experiment at LHC PMD photons MUON arm µ-pairs PMD Modules Muon chambers 7 7

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10 Light from QGP B.S. PLB 1983 q R γ/ µ + µ - = const( α, α s ) q µ + µ qq µ + µ - ~ T 4 10

11 Sometime ago it was noted that: B.S. PLB 1983 The ratio of the production rates (γ/µ + µ - ) and ( π o, ± /µ + µ - ) from quark gluon plasma is independent of the space time evolution of the fireball. Universal Signal : dσ 2 O( α T 4 d x + dσ d x µ µ 4 ) 4 ( 1 ) ( T O αα n ) 4 s l α s γ R γ µ µ s 1 ( 2 α ) α ln( α ) s (1) (2) + (3) Only a function of universal constants. 11

12 Photons at SPS 12

13 Thermal radiation from Au+ Au collisions at s**(1/2)=200-gev/a energy, (nucl-th/ , J. Alam, J. Nayak, P.Roy, A. Dutt- Mazumder, Bikash Sinha, J. Phys. G34: , 2007) Radiation at RHIC 13

14 ρ ω ϕ 14

15 15 Teff = T + M < vr > 2

16 RESULTS from the ratio: R em 2 d Nγ = 2 γ * T dy d pt dy ( 2 d N ( d 2 p ) The variation of R em (the ratio of the transverse momentum spectra of photons and dileptons) has been studied for SPS, RHIC and LHC. We argue that simultaneous measurements of this quantity will be very useful to determine the value of the initial temperature of the system formed after heavy ion collisions. We observe that Rem reaches a plateau beyond PT=1.5 GeV. The value of R em in the plateau region depends on T i but largely independent of T c, v o, T f and the EOS. 16

17 Effect of Large Flow Disappearance of Plateau 17

18 IMPORTANT UNIVERSAL DISCOVERY Universality of η s = 1 4 π Strong coupling behaviour of conformal gauge theories, Kovtun, Son and Starinetes (KSS bound) 18

19 Ultra Cold η s Saga Quantum degenerate, strongly interacting RHIC, Flow, QGP Atomic Fermi Gas PERFECT Fluid LHC? Microsecond Universe : QGP String Theory η s 1 4 π first experimentally accessible perfect liquid even isolated in the laboratory AdS / CFT Graphene Quantum Criticality Neutron Star? Finite Nuclei Strongly interacting System Giant Resonances (Nuclear matter) 19

20 Roy A. Lacey et. al PRL 98, (2007) η s λ ~ T c f s' 20 20

21 Hydrodynamic models to experimental data on charged hadron integrated elliptic flow by PHOBOS Glauber Elliptic Flow PHOBOS CGC Au + Au Collisions RHIC Au + Au Collisions RHIC M.Luzum & R. Romatschke, PRC (2008) 21

22 Hydrodynamic models to experimental data on charged hadron minimum bias elliptic flow by STAR Glauber Elliptic Flow STAR CGC M.Luzum & R. Romatschke, PRC (2008) 22

23 Quark-Gluon Plasma: A Perfect Fluid Viscous Hydrodynamics M.Luzum & R. Romatschke PRC (2008) η/s ~ 0 η/s = 1/4π Lowest Predicted Value (i.e. Perfect). η/s = 2 x 1/4π η/s = 3 x 1/4π String Theory (AdS/CFT) predicted η/s Bound Au + Au Collisions RHIC 23

24 The ratio of the shear viscosity to the entropy density is uniquely suited to determine how strongly the excitations in a quantum fluid interact. We determine η s η s s in clean undoped grapheneusing a quantum kinetic theory. As a results of the quantum criticality of this system the ratio is smaller thanin many other correlated quantum liquids and, interestingly, comes close to a lower bound conjectured in the context of the quark gluon plasma. η 24

25 M. Muller et. al arxiv: v2 [cond-mat.mes-hall] 14 Jul

26 Classical Nuclear Physics Collective Phenomena 1. Giant Resonances/proton & neutron fluids Hydro dynamical model => widths of resonances to the viscosity of the proton neutron fluids 26

27 2. Fission process At high temp : T >> h ω η s = h 4π k B 16 5π T F 2 α T Neutron Star? T F 2 η Unusually similar to RHIC results ~ h s 4π k What about Giant dipole resonances on highly excited state η s Auerbach & Shlomo, PRL, 103, (2009) B 27

28 The strongly coupled plasma By 2004, RHIC experiments determined and reported several key properties of the hot, dense matter. Its opacity to energetic quarks and gluons indicates extremely high density. Hydrodynamic descriptions reproduce the data and describe the collision from early times through expansion, cooling, and hadron formation, but only if η/s is taken to be very small. The system is therefore not the weakly coupled gas of almost freely moving quarks and gluons one would naively expect from asymptotic freedom. Instead, it is strongly coupled. 28

29 The strongly coupled plasma The strong coupling implies that some correlation among the quarks and gluons may survive within the plasma phase near T c and produce multiplarticle interactions with near neighbors. Indeed, lattice QCD studies of energy-density correlations in a QGP at temperatures of 1-2 T c show small correlation peaks. The correlation is similar to the short-range order observed in ordinary liquids near the liquid-gas phase transition. 29

30 It is remarkable that both the coldest and the hottest matter on Earth exhibit very similar elliptic flow patterns, with Ad S / C F T. η s near the conjectured lower bound, What does the FLOW at LHC tell us about Intriguing, Interesting, Captivating!!! η s 30

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32 In a hydrodynamic model, invariant distribution of photon and dilepton are obtained by convoluting the photon/dilepton rate over the space-time evolution of the QGP fluid produced in the collisions. In the following we study viscous effects on photon and dileptons. Some of the details of the model can be found in [1]. [1] A. K. Chaudhuri and B. S., Phys. Rev. C83(2011)

33 Space-time evolution of the fluid was obtained by solving Israel-Stewart's 2nd order hydrodynamics, Hydrodynamic equations are closed with an equation of state (EOS). We use an EOS based on Wuppertal-Budapest lattice simulation. With initial conditions appropriate for 200 GeV Au+Au collisions, the equations are solved with the code AZHYDRO- KOLKATA developed at the Cyclotron Centre, Kolkata. viz : Chowdhury and Sinha as cited 33

34 Effect of viscosity on photon spectra and elliptic flow: Validity of hydrodynamics require that non-equilibrium contribution to photon spectra is smaller than the equilibrium contribution. For AdS/CFT limit for viscosity to entropy ratio, η/s=1/4π, hydrodynamics is applicable only in a limited pt region (marked by the arrow). It is important to have a consistent model, e.g. neglect of non-equilibrium correction to distribution function can lead to increased elliptic flow. 34

35 Viscous effect on dilepton production: Production rate of dileptons of invariant mass M, from the QGP phase can be approximated as [3], similar to photons, viscous effects on dilepton production is also large. pt spectra is hardened, elliptic flow is reduced. Also, viscous hydrodynamics remain applicable only in a limited pt range. Applicability range increase with invariant mass. 35

36 ALICE data for charged particles elliptic flow in 20-30%, 30-40% and 40-50% collision are best explained for fluid viscosity = In very central % collisions however, ALICE data prefer ideal fluid rather than a viscous fluid. η s 36

37 Chowdhury & Sinha To be published 37

38 The ratio is largely p T independent. The p T dependence of non-equilibrium correction largely cancels out. For low dilepton invariant mass M = 300 MeV, as expected, the ratio do not distinguish between viscosities, the curves are nearly identical for η s = For invariant mass M = 600 or 900 MeV on the other hand, the ratio depends on viscosity. 38

39 For dilepton mass M = 600 MeV, if the ratio is measured within 10 % accuracy, viscosity to entropy ratio can be estimated within an accuracy of ~ 5 %. The sensitivity is increased to ~ 2 % for invariant mass M = 900 MeV. 39

40 Our analysis indicates that the specific viscosity of the QGP produced in LHC collisions is similar to that for the strongly coupled QGP produced in RHIC collisions. 40

41 The temperature dependence of η is not yet s discovered. I believe there is substantial hope to discover the temperature dependence of η s and so, a more precise determination of the critical point (if it at all exists) as we reach the highest energy of LHC. 41

42 FROM THE TERRESTRIAL LIGHT to THE COSMIC LIGHT, NO ORDINARY LIGHT Light from large Megellanic clouds 150,000 light years away 42

43 Quark Nuggets & Dark Matter : Evolution of the universe, Einstein eqn. Robertson Walker space time 43

44 EOS for QGP ε P = = 3 at at 4 + B 4 B t 0 Τ

45 Death of a first order phase transition in the early universe Rapid Cross over BUT µ>0 : f(t) : many other uncertainties 1 st Order : finite baryon density No hadrons initially in the Universe, except quarks, gluons, leptons photons 45

46 A little Inflation at QCD epoch in the Early Universe Boeckel & Schaffner B : PRL (2010) Number of baryons in a commoving volume B 3 i B 2 i N a µ T a µ T i i vacuum energy starts to dominate over the radiation energy f final values after reheating µ θ T B i i 3 θ = a f a i µ T B f f T T 3 ~ 10 f i 3 f 3 B f µ B N=7 e-foldings : Resurrection (little inflation) 2 T ~ O( 1) 46

47 Sketch of a possible QCD-phase diagram with the commonly accepted standard evolution path of the universe as calculated e.g. in [Fromerth and Rafelski] depicted by the green path. [Source: Boeckel and Bielich, 2011, arxiv: v2 [astro-ph.co] and Fromerth and J. Rafelski, (2002), arxiv:astro-ph/

48 Sketch of a possible QCD-phase diagram with the evolution path of the universe in the little inflation scenario. [Source: Boeckel and Bielich, 2011, arxiv: v2 [astro-ph.co] 48

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50 Strange quark nuggets (SQN) L H L L H L L H L L Isolated expanding bubbles of low temp In high temp phase L H L Expanding bubbles meet L H Isolated shrinking bubbles of High temp phase 50

51 CEFT MODEL Glendenning & matsui o meson evaporation oo Sumiyoshi et al 1990 Baryon evaporation 51

52 Chromo electric Flux-tube fission P. Bhattacharya J. Alam S. Raha B.S. (PRD 93) dn B /dt = [dn B /dt ] ev + [dn B /dt] abs [dn B /dt] abs = -2π 2 [ n N υ N / m N T 2 ] exp [m N -µ Nθ / T ] [ dn B / dt ] ev 52

53 Q N s with baryon number N B at time t will stop evaporating (survive) if the time scale of evaporation τ ev (N B,t) N B dn B / dt ~ >> H -1 (t) = 2t of the universe 53

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56 MACHO (Gravitational Microlensing) Based on Milky way halo in the direction of LMC (Large Magellanic Clouds) ( ) M 0.5 M >> fusion threshold ~ M MACHOs are not normal baryonic matter Trapped false vacuum domains (TFVD): n B (substantial) 56

57 MACHOs Contd. SQN (n B ) Not usual baryons: yet account for the baryonic number Alcock C. et al., 1993, Nat, 365, 621 Alcock C. et al., 2000, ApJ, 542,

58 Total number of clumped SQN s within the horizon T now 3 0 K at a time ~ secs Since η = n b /n γ Number of baryons in the CDM (Ω CDM /Ω B ) Visible Baryons ~ : Ω CDM 0.03 Ω B 0.01 Total no. of baryons in Macho b n N N (nugget size ~ ) (nugget size ~ ) N macho

59 Massive Compact Halo Objects from the Relics of the Cosmic Quark-Hadron Transition The existence of compact gravitational lenses, with masses around 0.5 M, has been reported in the halo of the Milky Way. The nature of these dark lenses is as yet obscure, particularly because these objects have masses well above the threshold for nuclear fusion. Source: S. Banerjee et al., and B. Sinha, Mon. Not. R. Astron. Soc. 000, (2002), Alam J. et al. and B. Sinha, 1999, Ap J, 513, 572, Alock C et al., 1993, Nat, 365,621, Aubourg E. et al. 1993, Nat, 365, 623 Cont. 59

60 Cont. Massive Compact Halo Objects from the Relics of the Cosmic Quark-Hadron Transition In this work, we show that they find a natural explanation as being the evolutionary product of the metastable false vacuum domains (the so-called strange quark nuggets) formed in a first order cosmic quark-hadron transition. Source: S. Banerjee et al., and B. Sinha, Mon. Not. R. Astron. Soc. 000, (2002), Alam J. et al. and B. Sinha, 1999, Ap J, 513, 572, Alock C et al., 1993, Nat, 365,621, Aubourg E. et al. 1993, Nat, 365,

61 Bag constant B = (145MeV) 4 => M macho 1.4 M within SQN s limit SQN s are Machos 61

62 Relics of the cosmological QCD phase transition The abundance and size distribution of quark nuggets (QN s), formed a few microseconds after the big bang due to a first-order QCD phase transition in the early universe, has been estimated. Source: A. Bhattacharyya et al. and B. Sinha, Phy. Rev. D. (vol61, 2000) Cont. 62

63 Cont. Relics of the cosmological QCD phase transition It appears that stable QN s could be a viable candidate for cosmological dark matter. The evolution of baryon inhomogeneity due to evaporated (unstable) QN s is also examined. Source: A. Bhattacharyya et al. and B. Sinha, Phy. Rev. D. (vol61, 2000) 63

64 Charts of nuclides shows all known forms of stable matter. Between the heaviest atomic elements and neutron stars, which are giant nuclei, lies a vast, unpopulated nuclear desert. This void may actually be filled with strange quark matter. 4

65 in simple terms ; what exactly is the difference First order Crossover

66 THROUGH THE LOOKING GLASS Lewis Carroll Alice in Quark Land The time has come, the Walrus said, To talk of many things: Of shoes and ships and sealing-wax- Of cabbages and kings- And why the sea is boiling hot And whether pigs have wings. NO RELICS VS RELICS

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