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Spectral shapes in pp collisions

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Presentation on theme: "Spectral shapes in pp collisions"— Presentation transcript:

1 Spectral shapes in pp collisions
Mt-scaling for soft particles Power-law tail from hard scattering Increasing with energy

2 Scaling of spectra in dA and AA collisions
mT scaling in pp and dA, but NOT in AA. Signature of radial flow.

3

4 Fitting p,K,p with hydrodynamics model
40-50% 80-92% 0-5%

5 Blast wave fits: Tfo and flow velocity

6 Flow velocity vs energy
< bT > slowly increasing from AGS to SPS to RHIC

7 Basics of Hydrodynamics
Hydrodynamic Equations Energy-momentum conservation Charge conservations (baryon, strangeness, etc…) Need equation of state (EoS) P(e,nB) to close the system of eqs.  Hydro can be connected directly with lattice QCD For perfect fluids (neglecting viscosity), Energy density Pressure 4-velocity Within ideal hydrodynamics, pressure gradient dP/dx is the driving force of collective flow.  Collective flow is believed to reflect information about EoS!  Phenomenon which connects 1st principle with experiment Caveat: Thermalization, l << (typical system size)

8 Inputs to Hydrodynamics
Final stage: Free streaming particles  Need decoupling prescription t Intermediate stage: Hydrodynamics can be valid if thermalization is achieved.  Need EoS z Initial stage: Particle production and pre-thermalization beyond hydrodynamics Instead, initial conditions for hydro simulations Need modeling (1) EoS, (2) Initial cond., and (3) Decoupling


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