Big Bang to Little Bang ---- Study of Quark-Gluon Plasma. Tapan Nayak July 5, 2013

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1 Big Bang to Little Bang ---- Study of Quark-Gluon Plasma Tapan Nayak July 5, 2013

2 Universe was born through a massive explosion At that moment, all the matter was compressed into a space billions of times smaller than a proton. That was the Beginning of space and time. Since that moment the cosmic bodies are moving away from each other => expanding Universe About 13.7 Billion Years ago (~1370 Crore years ago) Temperature ~ o C

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4 FUNDAMENTAL STRUCTURE OF MATTER MATTER ATOM NUCLEUS Protons/ neutrons QUARKS 10-8 cm cm cm

5 Fundamental forces of nature Attractive Gravitational force Massive Body Massive Body Between two massive bodies Weak in nature Very long range Weak force One example is beta decay Weak in nature Short range Between two fundamental particles Electromagnetic force + - Between electric or magnetic charges Long range Attractive or Repulsive Strong force Holds the atomic nucleus, Quarks in neutron/proton Range cm Basically attractive

6 Except GRAVITY, everything around us in our daily life works by Electromagnetic Interactions Electric Lines of Force

7 Structure of an atom electron separate constituents nucleus

8 quark-antiquark pair created from vacuum quark white proton (baryon) (confined quarks) Strong color field white π 0 (meson) Force white grows proton with separation (confined!!! quarks)

9 9 Quark Gluon Plasma

10 PHASE DIAGRAM 1 ev is roughly Kelvin

11 Quark Gluon Plasma in the Laboratory Collide Heavyions at almost the speed of light Create the Little Bangs in the Laboratory

12 Relativistic Heavy Ion Collider (RHIC) Brookhaven National Laboratory First confirmation of QGP Formation Beam Energy Scan => Search for Critical Point

13 CERN CMS Large Hadron Collider ALICE LHC-B ATLAS

14 LHC Tunnel 27km tunnel: m below ground Two beams of protons/heavy-ions circulating in opposite directions Total of 9300 magnets: beams controlled by 1800 superconducting magnets (up to 8T)

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16 (IIT-B) (Jammu Univ.) (Panjab Univ.) (Rajasthan Univ.) (AMU) Guwahati (Univ. of Guwahati) (VECC, SINP, Bose Inst.) ~100 Members Kolkata: VECC Kolkata: SINP Kolkata: Bose Institute Aligarh: Aligarh Muslim University Bhubaneswar: Institute of Physics Bhubaneswar: NISER Chandigarh: Panjab University Guwahati: University of Guwahati Indore: IIT Jaipur: Rajasthan University Jammu: University of Jammu Mumbai: Indian Institute of Technology, Bombay Mumbai: BARC (IOP) Involvement of Indian Scientists since the beginning of ALICE

17 Pb + Pb Collision at NN c.m. energy: 2.76 TeV

18 18 Initial Energy Density Bjorken 1983 Boost invariant hydrodynamics: T C ~ 170 ±15 MeV ε C ~ GeV/fm 3 ε 0 ~ 0.16 GeV/fm 3 dz = τ dy 0 ε Bj (τ ) = 1 de T π R 2 τ dy πr 2 ε.τ ~ 16 GeV/fm 2 c at LHC Much more than the energy density for the formation of QGP.

19 D Hadron Gas: Charge unit = 1 QGP: Charge unit = fractional D Q is net-charge. Hadronic phase D ~ 3 Predictions QGP phase D ~ PRL Physical Review Letters, vol. 110 Feb 2013 FIRST EVIDENCE OF QGP FROM FLUCTUATION MEASURE corr (+-,dyn) ch N Hadron Gas 10 Hadron Gas QGP STAR Au-Au RHIC ALICE Pb-Pb = 1.0 ALICE Pb-Pb = 1.6 QGP 10 2 s NN (GeV) 3 10 LHC

20 Thermal Photons from QGP Quark Gluon Plasma emits thermal photons with wavelength λ ~ 1 x m and power proportional to T 4. Photons do not interact via the nuclear force and thus the Quark Gluon Plasma is transparent to them. First Theoretical Basis: Sinha & Srivastava Photon Sources Direct photons from initial hard scattering of quarks and gluons Decay Photons from hadrons (π 0, η, etc): Challenge is to separate the thermal part.

21 Direct Photon production (ALICE) HIGHEST MAN-MADE TEMPERATURE Exponential fit for p T < 2.2 GeV/c inv. slope T = 304±51 MeV for 0 40% Pb Pb at s 2.76 TeV PHENIX: T = 221±19±19 MeV for 0 20% Au Au at s 200 GeV T = = 304±51 MeV ~ 5.5 Trillion degrees (As a reference, an average energy of 1 MeV corresponds to a temperature of K.)

22 Mapping the Phase Diagram To understand the nature of the phase transition To probe the QCD Critical Point Energy dependence of the temperature derived from the spectra of kaons in central collisions. A step-like behaviour is observed, where the transition between the confined to deconfined matter takes place.

23 Fluctuations in CMBR and Collisions at LHC MAP coming up soon WMAP: Temperature Fluctuations of the Cosmic Microwave Background. LHC Heavy Ions: Event-by-Event FLUCTUATIONS o: Conserved Quantities, Temperature

24 Phases of Nuclear Matter First results for Little Bangs at LHC indicates: - matter created at LHC is an ideal fluid which is extremely dense and hot - matter in which quarks and gluons may not be confined within this fluid. There is a lot more discoveries coming up!!!!