1 / 17

Advanced Estimation of Initial Energy Density in LHC Proton-Proton Collisions

This study presents an advanced estimation of the initial energy density in proton-proton collisions at the LHC, utilizing the Bjorken formula. Through detailed analytical investigations and corrections relating to acceleration and equation of state (EoS), we refine previous estimates, yielding an initial energy density of approximately 1.14 GeV/fm³. This value raises crucial questions regarding the critical energy density threshold of 1 GeV/fm³, and its implications for understanding the properties of the Quark-Gluon Plasma (QGP) phase.

tasya
Télécharger la présentation

Advanced Estimation of Initial Energy Density in LHC Proton-Proton Collisions

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. ZIMÁNYI SCHOOL 2013 December 2-6. Budapest, Hungary INITIAL energydensityin LHC P+Pcollisions M. Csanád &T. Csörgő 02 Dec2013

  2. The Bjorken-estimate • The original idea: energydensitybasedondE/dy • QGP criticale: 1 GeV/fm3 (fromec=6-8Tc4) • Result (~2000x cited) • Needscorrection! • Ref.: Phys.Rev. D27 (1983)

  3. An advancedestimate • Fact: dn/dynotflat • Finiteness & acceleration • Analyticalinvestigation: • Accelerationparameterl • Twomodifications: • yh & hfinal hinitial • Workbyacceleration! • Correctionw.r.t. EoS: E.g.: J.Phys.G35 (2008) 104128 (arXiv:0805.1562)

  4. Initialenergydensityat LHC • RoughestimatepossibleviatheBjorken formula • Number of particlesatmidrapidity: 5.89 (CMS, ALICE) • Averageenergy: mt=0.562 GeV (CMS) • Initialradius of thesystem R: ~1.081 fm (TOTEM, sinel) • Formationtimet0: 1 fm/c (conservativeestimate) • Energydensityfromthis: • Justbelowcritical? Importantquestion!

  5. Correctionfrominitialacceleration • Initialaccelerationpushesoutervolumeelements • Thismodifiesthedn/dhdistribution • Estimateaccelerationfromit! • l = 1: no acceleration • TOTEM fit: l = 1.0730.0010.004 • WithoutEoS: 20%

  6. TOTEM & CMS datacombined (7 TeV) • Fit results: • TOTEM: • CMS: • Jointdata: • Normalization OK? • Singlediffractive vs. non-singlediffractive? • Lambdadoesnot changesignificantly

  7. Comment: dn/dh @ 7 TeV is nottrivial • Nottrivialfor MC models • TOTEM Coll., EPL, 98 (2012) 31002

  8. Preliminaryresultson 8 TeV • CMS vs. TOTEM normalizationnottrivial • Both datasetsdescribableby • Joint fit: • Data arenot final • Systematic analysiscoming

  9. Dependenceonparticlenumber • Severalmultiplicityclasses, 6-20, even 30 seen!

  10. Initialtemperatureestimate • Temperaturefrome~T4

  11. Systematicuncertainties • Allsources of uncertainties: • Conclusionat 7 TeV: • eini= (1.14  0.01(syst) +0.21-0.16 (syst)) GeV/fm3

  12. Is itunprecedented? Consequences? • Bjorken and Landau worked out hydro for pp and pA • Success of hydro to describe h+p, with <n> = 7-8... Phys.Lett. B422 (1998) 359-368 • Bjorken: it is not hadrons that play billiard balling • If p+p is a complexsystem: • Gamma/pi0 ratio • Radialflow • Elliptic flow,scaling • HBT radii,scaling • Lowmassdileptonenhancement • Directphotonenhancement • RAAmightnot be thebestmeasure: dividebylengthscale?

  13. Summary • ExperimentallywidelyusedBjorken est. at 7 TeV • Advanced estimate: accelerationwork, fromdn/dh • Resultsontheinitialefor cs2=0.1, attf/tini=2 • From TOTEM data: eini= (1.14  0.01  0.2) GeV/fm3 • ThisatdN/dy=6 & linearlyriseswithmultiplicity! • Criticalenergydensity: 1 GeV/fm3 • Resultsnotincompatiblewithsupercrit. sQGP phase

  14. Initialenergydensityat RHIC • Bjorkenestimatefrom BRAHMS: 5 GeV/fm3 • Advanced estimategives: • Correction: 2-3x, result 15 GeV/fm3, QCD agreement! • Correspondsto Tini 2Tc  340 MeV • Confirmedbyphotonspectraat PHENIX, published 2010 • Referencee.g.: J.Phys.G35 (2008) 104128 (arXiv:0805.1562)

  15. A solution of relativistichydro • Velocity: tanh(lh) • Acceleration: l1 • Density: (t/t0)l • dn/dycalculable! • Comparethisto RHIC data! • dn/dymeasurementyieldsadvancedinitialeestimate • Significantcorrectionat RHIC! • Reference: Phys.Lett. B663 (2008) 306-311 (nucl-th/0605070)

  16. Advanced estimateat 7 TeV • Fit result: l=1.073 • Conservatively: cs2=0.1 • ~25% correction • Input parameters: • dN/dyatmidrap.: 5.89 • Averagemt: 0.562 GeV • Area: 3.67 fm2 • Fromcrosssections • Freeze-outtime / form. time: atleast 2 • Bjorkenresult: 0.90 Gev/fm3 • Correctedresult: 1.14 GeV/fm3

  17. Sources of uncertainties • Forthecorrectionfactore/eBj: • Fit parameterl • Statisticalerror (fromthedata) • Speed of sound cs2 • Durationtf/ti • FortheoriginalBjorken-estimate: • Main uncertaintysource: multiplicityatmidrapiditydN/dy • Area (iftakenfromcross-section): veryprecise • Formationtime • Averagetransversemass

More Related