Publications

Below selected publications are highlighted, a full list of publications can be found on INSPIRE.  

My PhD thesis can be found here

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RAA to v2 puzzle

 

Event-by-Event fluctuations and Jets

High pT > 10 GeV elliptic flow, which is experimentally measured via the correlation between soft and hard hadrons, receives competing contributions from event-by-event fluctuations of the low pT elliptic flow and event plane angle fluctuations in the soft sector. In this paper, a proper account of these event-by-event fluctuations in the soft sector, modeled via viscous hydrodynamics, is combined with a jet energy loss model to reveal that the positive contribution from low pT v2 fluctuations overwhelms the negative contributions from event plane fluctuations. This leads to an enhancement of high pT > 10 GeV elliptic flow in comparison to previous calculations and provides a natural solution to the decade long high pT RAA ⊗ v2 puzzle. We also present the first theoretical calculation of high pT v3, which is shown to be compatible with current LHC data. Furthermore, we discuss how short wavelength jet-medium physics can be deconvoluted from the physics of soft, bulk event-by-event flow observables using event shape engineering techniques.

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v-USPhydro

 

Shear vs. Bulk viscosity

The interplay between shear and bulk viscosities on the flow harmonics, vn’s, at RHIC is investigated

using the newly developed relativistic 2+1 hydrodynamical code v-USPhydro that includes

bulk and shear viscosity effects both in the hydrodynamic evolution and also at freeze-out. While

shear viscosity is known to attenuate the flow harmonics, we find that the inclusion of bulk viscosity

decreases the shear viscosity-induced suppression of the flow harmonics bringing them closer

to their values in ideal hydrodynamical calculations. Depending on the value of the bulk viscosity

to entropy density ratio, ζ/s, in the quark-gluon plasma, the bulk viscosity-driven suppression of

shear viscosity effects on the flow harmonics may require a re-evaluation of the previous estimates

of the shear viscosity to entropy density ratio, η/s, of the quark-gluon plasma previously extracted

by comparing hydrodynamic calculations to heavy ion data. See more

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p/pi puzzle

 

Effects of Extended Mass Spectrum

Recent measurements of the proton to pion ratio at s√NN=2.7 TeV by the ALICE collaboration at the LHC have found it to be lower than predictions from thermal fits. In this paper we investigate the role that the extended mass spectrum via Hagedorn states- massive resonances that follow an exponential mass spectrum and possess large decay widths- play in the determination of particle ratios at LHC through a scenario of multi-particle reactions and dynamical chemical equilibrium within the hadron gas phase. We show that it is possible to describe the lower p/π ratio at LHC while still obtaining the experimental ratio of K/π and Λ/π+ in the Hagedorn state scenario if the protons are underpopulated at the switching temperature from hydrodynamics to the hadron gas phase. See more

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   viscosity

 

Transport Coefficients

A hadron resonance gas model including all known particles and resonances with masses m < 2

GeV and an exponentially rising density of Hagedorn states for m > 2 GeV is used to obtain an

upper bound on the shear viscosity to entropy density ratio, η/s ≈ 1/(4π), of hadronic matter near

Tc. We found a large trace anomaly and small speed of sound near Tc, which agree well with recent

lattice calculations. We comment on the bulk viscosity to entropy density ratio close to Tc.  See more and here

Just a sample of my work, INSPIRE has a full list of my publications >>