1 / 40

Verification of Z scaling in pp collisions at RHIC

Verification of Z scaling in pp collisions at RHIC. M. Tokarev ( JINR,Dubna ) & I. Zborovsk ý ( NPI, Řež ). Outline. Introduction (motivation and goals) Z -scaling & ideas and definitions Properties of the scaling function Y (z) Z -scaling in pp collisions at RHIC

van
Download Presentation

Verification of Z scaling in pp collisions at RHIC

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. Verification of Z scaling in pp collisions at RHIC M. Tokarev (JINR,Dubna) & I. Zborovský (NPI, Řež)

  2. Outline • Introduction (motivation and goals) • Z-scaling & ideas and definitions • Properties of the scaling function Y(z) • Z-scaling in pp collisions at RHIC (analysis of h±,π0,η,0,KS,K*,φ, Λ,Ξ,γ spectra) • Multiplcity dependence of Z-scaling • Summary ¯ ¯

  3. Scaling analysis in high energy interactions transverse mass Feynman variable Scaling variables radial scaling variable light-cone variable Bjorken variable The scaling regularities have restricted range of validity Z-scaling: it provides universal description of inclusive particle cross sections over a wide kinematical region (central+fragmentation region, pT > 0.5 GeV/c, s1/2 > 11 GeV )

  4. Motivation & Goals Development of universal phenomenological description of high-pT particle production in inclusive reactions to search for: - new physics phenomena in elementary processes (quark compositeness, fractal space-time, extra dimensions, ...) - signatures of exotic state of nuclear matter (phase transitions, quark-gluon plasma, …) - complementary restrictions for theory (nonperturbative QCD effects, Standard Model, ...). Analysis of new pp experimental data obtained at RHIC to verify Z-scaling observed at U70, ISR, SppS and Tevatron in high-pT particle production. ¯

  5. Self-similarity principle Self-similarity in inclusive particle production at high energies The self-similarity parameter z is specific dimensionless combination of quantities which characterize particle production in high energy inclusive reactions. It depends on momenta and masses of the colliding and inclusive particles, multiplicity density and fractal dimensions of the interacting objects. The self-similarity is property connected with dropping of certain dimensional quantities out of description of physical phenomena. Self-similarity parameters are constructed as combinations of these quantities. Search for self-similar solutions (inclusive cross sections) expressed via a scaling function Ψ(z). The scaling variable z depends on: 1. Reaction characteristics (A1, A2, s) 2. Characteristics of the inclusive particle (m, E, ) 3. Dynamical characteristics of the interaction (dN/dh,...) 4. Structural characteristics of the interacting objects (d1, d2, ε)

  6. Gross features of inclusive particle distributions for the reaction are expressed in terms of the constituent sub-process Momentum fractions and are determined in a way to minimize the resolution of the fractal measure . Locality principle Locality of the hadronic interactions at constituent level is expressed by the 4-momentum conservation law V.S.Stavinsky, A.M.Baldin,…

  7. p Fractality principle Principle of fractality states that variables used in description of the processes diverge in terms of resolution. The scaling variable z = z0Ω-1is fractal measure depending on the resolution W-1with respect to all constituent subprocesses in which the inclusive particle with the momentum p can be produced. z(Ω)→∞ for Ω→0 We consider structural particles (hadrons, nuclei,…) as fractal objects revealing structure at small scales Fractality in soft processes: A.Bialas, R.Peschanski, A.Bershadskii, I.M.Dremin, E.De Wolf, V.Khoze, W.Kittel, …

  8. Charged hadrons p0 • High-pT hadrons • Jets • Direct photons • D-Y lepton pairs • W ±, Z0 -bosons • Heavy quarkonia Jets Di-Jets Direct photons High-pTregime is well controled by pQCD Self-similarity, locality and fractality in hard processes Phys. Rev. D54 (1996) 5548. Phys. Rev. C59 (1999) 2227. Int. J. Mod. Phys. A15 (2000) 3495. J.Phys.G:Nucl.Part.Phys.26(2000)1671. Int. J. Mod. Phys. A16 (2001) 1281. Acta Physica Slovaca 54 (2004) 321. Sov.J.Nucl.Phys. 67 (2004) 583. Sov.J.Nucl.Phys. 68 (2005) 404.

  9. is the transverse energy of the subprocess • dN/dh is the multiplicity density at h=0 • W-1is resolution with respect to constituent subprocess andW depend on x1 and x 2 Scaling variable Z Principle of minimal resolution: Momentum fraction x1 and x2 are determined in a way to minimize the resolution W-1with respect to all constituent subprocesses taking into account energy-momentum conservation law. Momentum fractions x1,2consist of a-dependent and independent parts (l-c decomposition)

  10. Transverse energy of subprocess transverse energy of recoilparticle transverse energy of inclusive particle The variable z is expressed via momenta (P1 , P2 , p) and masses (M1 , M2 , m1) of colliding and produced particles and charged particle multiplicity density (dN/dh| h=0).

  11. Fractal property of the scaling variable z has character of a fractal measure For a given production process, the finite part z0 is ratioof the transverse energy released in the underlying collision of constituentsand the average multiplicity densitydN/dh|h=0 . The divergent partW-1describes resolution at which the collision ofthe constituents can be singled out of this process. is relative number of all initial configurationscontaining the constituents which carry the fractions x1 and x2 of the incoming momenta P1 and P2. d1and d2are anomalous fractaldimensions of the collidingobjects (hadrons or nuclei).

  12. s1/2 is the colliding energy dN/dh(s) is the pseudorapidity multiplicity density sinel(s) is the inelastic cross section J is the corresponding Jacobian is the inclusive cross section Scaling function Y(z) Normalization equation The scaling function Y(z) is probability density to produce inclusive particle with formation length z.

  13. Properties of z-presentation of experimental data • Energy independence of Y(z) • Angular independence of Y(z) • Power behavior Y(z) ~ z -b • A-dependence of Y(z) • F-dependence of Y(z) • Multiplicity independence ofΨ(z) The scaling function has same shape for different s1/2. The scaling function has same shape for different q0 . The scaling function reveals power asymptotic regime. The scaling function has same shape for different nuclei. Same asymptotics of the scaling function for different secondaries. Same shape of Ψ(z) for different multiplicities. Confirmation of these properties is possible at RHIC,Tevatron and LHC

  14. Relativistic Heavy Ion Collider, RHIC • 3.83 km circumference • Two separated rings • 120 bunches/ring • 106 ns bunch crossing time • A+A, p+A, p+p • Maximum Beam Energy : • 500 GeV for p+p • 200A GeV for Au+Au • Luminosity • Au+Au: 2 x 1026 cm-2 s-1 • p+p : 2 x 1032 cm-2 s-1 • Beam polarizations • P=70% PP2PP RHIC Upton, Long Island, New York

  15. Phys.Rev.Lett. 91 (2003) 172302 RHIC RHIC Z-scaling at RHIC Charged hadron production in pp collisions from STAR Z-scaling at RHIC& Non-single diffractive data from STAR Charged hadron production in pp collisions RHIC Tevatron ISR U70 STAR confirms Z-scaling

  16. Z-scaling at RHIC p0-meson production in pp collisions from PHENIX PHENIX ISR RHIC ISR RHIC The cross section Ed3s/dp3vs. pT. The scaling functionY(z)vs. z. p0→ gg m=135 MeV ct = 251Å Br = 98.8% D.d’Enterria Energy independence of Y(z) is observed up to z ≈ 30. Power law Y(z) ~ z-b is observed for z > 4. M.T., Dedovich, O.Rogachevsky J.Phys.G:Nucl.Part. Phys.26(2000)1671 PHENIX Collaboration S.S.Adler et al., Phys.Rev.Lett. 91(2003)241803 PHENIX confirms Z-scaling H.Büschening, Hard Probes, Portugal, Nov.8, 2004 S.S.Adler et al., PRL 91 (2003) 241803 H.Büschening, DNP-Chicago, Oct.2004. D.d’Enterria, Hard Probes, Ericeira, Portugal, Nov.7, 2004 p0→gg (135 MeV/c2, 251Å, 98.8%),

  17. RHIC Z-scaling at RHIC h-meson production in pp collisions from PHEINX PHENIX RHIC RHIC RHIC RHIC The cross section Ed3s/dp3vs. pT. The scaling functionY(z)vs. z. h→ gg m=547 MeV ct = 11 Ǻ Br = 38.8% Energy independence of Y(z) is observed up to z ≈ 20. Power law Y(z) ~ z-b is observed for z > 4. PHENIX Collaboration H.Hiejima, QM’04, January, 2004, Oakland, USA PHENIX Collaboration D.d’Enterria, Hard Probes’04, November, 2004, Ericeira, Portugal PHENIX confirms Z-scaling M.T., T.Dedovich, O.Rogachevsky J.Phys.G:Nucl.Part. Phys.26(2000)1671 hgg (547 MeV/c2, 11Å, 39.2%),

  18. Mechanism of strange mesons and baryons production in pp collisions • s & s PDF’s and FF’s • pp data are baseline for understanding of particle production in nuclear medium ¯ Figure1. Invariant pT spectra for L andX+ +X- for the top 5% central Au-Au data and p-p minbias. The p-p data is scaled by a factor of 10 for clarity. Transverse momentum spectra of strange particles in pp collisions at STAR STAR measures the strange particle spectra with great improvement in statistical errors STAR collaboration M.Heinz (University of Bern) 40th Rencontres de Moriond, 12-19 March, 2005, La Thuile, Italy H. Cines Yale University for the STAR Collaborations “Quark Matter 2005”, 4-9 August, 2005, Budapest, Hungary

  19. RHIC RHIC Z-scaling at RHIC K+ &KS0-meson production in pp collisions at high-pT Ed3s/dp3vs. pT Y(z)vs. z Experimental data: J.W. Cronin et.al., Phys. Rev. D11 (1975) 3105. D. Antreasyan et al., Phys. Rev. D19 (1979) 764. V.V. Abramov et al., Sov. J. Nucl. Phys. 41 (1985) 357. D.E. Jaffe et al., Phys. Rev. D40 (1989) 2777. B.Alper et al., Nucl. Phys. B87 (1975) 19. KS0 → p+p- m= 494MeV ct = 2.67 cm Br = 68.6% • Shape of Ψ(z)for K+ & KS0 • F-dependence of Y(z) • High-pT asymptotic of KS0 Indication on validity of Z-scaling for KS0 STAR Collaboration J. Adams & M. Heinz, QM’04, January, 2004, Oakland, USA (nucl-ex/0403020) KS0 →p+p- (494 MeV/c2, 2.7cm, 68.6%)

  20. M.Tokarev T.Dedovich O.Rogachevsky J.Phys.G:Nucl.Part. Phys.26(2000)1671 The cross section Ed3s/dp3vs. pT The scaling functionY(z)vs. z F-dependence of Y(z) Z-scaling at RHIC -hyperon production in pp collisions from STAR Predictions based on STAR data Λ0(uds) Energy independence of Y(z) F-dependence of Ψ(z) Power law, Y(z) ~ z-b L0→ pp- m=1.12 GeV ct = 7.89 cm Br = 63.9% STRANGENESSorigin in anti-hyperons STAR Collaboration J. Adams & M. Heinz, QM’04, January, 2004, Oakland, USA (nucl-ex/0403020) L0p p- (1.12 GeV/c2, 7.9cm, 63.9%),

  21. The cross section Ed3s/dp3vs. pT Ξ-(ssd) B.Bezverkhny, Yale University(for the STAR Collaborations) “Quark Matter 2005”, 4-9 August, 2005, Budapest, Hungary The scaling functionY(z)vs. z F-dependence of Y(z) Z-scaling at RHIC -hyperon production in pp collisions from STAR RHIC can test Z-scaling at s1/2 = 50-500 GeV Energy independence of Y(z) Power law, Y(z) ~ z-b X -→ Lp- m=1.32 GeV ct = 4.91 cm Br = 99.9% STRANGENESS origin in baryons STAR Collaborations B.Bezverkhny (Yale University) “Quark Matter 2005”, 4-9 August, 2005, Budapest, Hungary STAR Collaboration R.Witt et al., nucl-ex/0403021 Ξ-→Lp- (1.32 GeV/c2, 4.9cm, 99.9%)

  22. The cross section Ed3s/dp3vs. pT f(ss) ¯ The scaling functionY(z)vs. z F-dependence of Y(z) Z-scaling at RHIC f-meson production in pp collisions from STAR M.Tokarev T.Dedovich O.Rogachevsky J.Phys.G:Nucl.Part. Phys.26(2000)1671 STAR Predictions based on STAR data Energy independence of Y(z) F-dependence of Ψ(z) Power law, Y(z) ~ z-b f→K+K– m=1.02 GeV ct = 44 fm Br = 49.1% STRANGENESSorigin in f meson STAR Collaboration J.Adams et al., nucl-ex/0406003 f→K+K- (1.02 GeV/c2, 280fm, 49.1%)

  23. The cross section Ed3s/dp3vs. pT The scaling functionY(z)vs. z F-dependence of Y(z) Z-scaling at RHIC K(892)*-meson production in pp collisions from STAR STAR Energy independence of Y(z) F-dependence ofΨ(z) Power law, Y(z) ~ z-b K*→K π m=892 MeV c ≈ 3.9 fm Br ≈100% Origin of vector mesons STAR Collaboration J.Adams et al., nucl-ex/0412019 RHIC can verify Z-scaling

  24. The cross section Ed3s/dp3vs. pT The scaling functionY(z)vs. z F-dependence of Y(z) Z-scaling at RHIC 0-meson production in pp collisions from STAR STAR Energy independence of Y(z) F-dependence of Ψ(z) Power law, Y(z) ~ z-b 0→ π+ π– m=770 MeV ct = 1.3 fm Br ≈100% • Origin of vector mesons • Probe of nuclear matter STAR Collaboration J.Adams et al., Phys. Rev. Lett. 92 (2004) 092301 RHIC can verify Z-scaling

  25. +,K+,P -,K-, P RHIC RHIC Z-scaling at RHIC p--meson production in pp collisions at high-pT 1/2πpT d2N/dpTdy , (GeV/c)-2 STAR & PHENIX STAR & PHENIX The scaling functionY(z)vs. z The cross section Ed3s/dp3vs. pT • Energy scaling (up to z ≈ 30) • Power law Y(z) ~ z-b (z > 4) Experimental data: J.W. Cronin et.al., Phys. Rev. D11 (1975) 3105. D. Antreasyan et al., Phys. Rev. D19 (1979) 764. V.V. Abramov et al., Sov. J. Nucl. Phys. 41 (1985) 357. D.E. Jaffe et al., Phys. Rev. D40 (1989) 2777. Spectra of ID’d hadrons at high pT RHIC confirms Z-scaling The scaling functionY(z)vs. z. STAR Collaboration, O.Barannikova, QM’05, August, 2005, Budapest, Hungary PHENIX Collaboration, M. Harvey, QM’04, January, 2004, Oakland, USA The cross section Ed3s/dp3vs. pT.

  26. Direct Process photon photon Compton/Annihilation process Direct photon production Fragmentation Process • Parton Distribution & Fragmentation Functions are taken from DIS & e+e- • Deviation from NLO QCD fit to data is signature of new physics

  27. ¯ Z-scaling at SppS and Tevatron in Run I,II Direct photon production in pp collisions ¯ M.T. E.Potrebenikova JINR E2-98-64 Comput.Phys.Com. 117 (1999) 229 M.T. G.Efimov hep-ph/0209013 M.T. G.Efimov D.Toivonen Sov.J.Nuc.Phys. 67 (2004) 583 The cross section Ed3s/dp3vs. pT. The scaling functionY(z)vs. z. • Energy dependence of spectra • Power law, slope parameter depends on s1/2 and pT Don Lincoln (for the DØ & CDF collaborations) “XXV Physics in Collision 2005”, 6-9 July, 2005, Prague, Czech Republic • Energy independence of Y(z) • Power law, Y(z) ~ z-b

  28. Z-scaling at RHIC Direct photon production in pp collisions from PHENIX PHENIX ISR RHIC ISR RHIC RHIC RHIC The cross section Ed3s/dp3vs. pT The scaling functionY(z)vs. z Energy independence of Y(z) is observed up to z ≈ 30. Power law Y(z) ~ z-b is observed for z > 5. PHENIX Collaboration K.Okada, “Spin 2004”, October 11-16, 2004, Trieste, Italy hep-ex/0501066 M.T., Dedovich, O.Rogachevsky J.Phys.G:Nucl.Part. Phys.26(2000)1671 • NLO pQCDdescribes data within exp. errors • Sensitivity of data toproperties of z-presentation

  29. Measured multiplicity density dNch/dh in pp & pp is much more larger than dNch/dh/(0.5Np) in central AA collisions at AGS, SppS and RHIC ¯ ¯ Medium produced in pp & AA collisions • Is medium produced in pp collisions at high dNch/dh similar to nuclear medium created in central AA ? • Are there general properties of particle production mechanism in pp & AA ? • Particle multiplicity <Nch> • Multiplicity density dNch/dh • Mean transverse momentum <pT> • Energy density eBj ~ 1/(R2) dET/dy

  30. Central Au-Au s1/2=200 GeV Quarks & Gluons Mesons & Baryons pp s1/2 = 200 GeV RHIC & STAR RHIC & STAR Multiplicity selection of events • low pT spectra→ exponential law • multiplicity evolution of hadronization • “invisible” quark & gluon degrees of freedom ↔ no constituent structure • high pT spectra→ power law • pT evolution of hadronization • constituent structure is visible • Multiplicity density dNch /dhis characteristic of nuclear medium • Modification of particle spectra with multiplicity density, RAA(pT) & RCP (pT) • Multiplicity density ~ gluon density at small x → saturation regime (CGC, QGP) L.McLerran, D.Kharzeev,…

  31. is minimal transverse energy of the subprocess • dN/dh is the multiplicity density at h=0 • W-1is resolution with respect to constituent subprocesses • y is momentum fraction of secondary parton carried out by inclusive particle andWdepend on x1, x2, y Generalized scaling variable z Principle of minimal resolution: The momentum fractions x1, x2 and y are determined in a way to minimize the resolution W-1 of the fractal measure z with respect to all constituent subprocesses taking into account the energy – momentum conservation: M.T., I.Zborovsky hep-ph/0506003

  32. is minimal transverse energy of the subprocess • dN/dh|0 is multiplicity density at h=0 • W-1is fractal resolution with respect to constituent subprocesses • W is relative number of all configurations in the colliding system from which the inclusive particle with the momentum p can be produced Entropy Thermodynamical Statistical • The quantities cand dN/dη|0have physical meaning of “heat capacity” and “temperature” of medium, respectively. • Entropy of medium decreases with increasing resolution Ω-1 . Scaling variable z &entropy S The specific heat calculated from multifractal analysis of hadron and nucleus interactions can be used as a universal characteristic of the multiple production. A.Bershadskii, Physica A253 (1998) 23.

  33. Multiplicityindependence of Z-scaling Charged hadron production in pp collisions at Tevatron and SppS ¯ ¯ UA1 E735 |η|<2.5 |η|<2.5 CDF |η|<3.25 c=0.25 c=0.25 |η|<3.25 c=0.25 UA1 Collaboration G. Arnison et al., Phys. Lett. B118 (1982) 167. CDFCollaboration D.Acosta et al., Phys. Rev. D65 (2002) 072005. • Strong dependence of high pT spectra on multiplicity • Sensitivity of Y(z) to the resolution Ω-1: z ~ Ω–1 • Sensitivity of Y(z) to heat capacity c: z ~ (dN/dη)–c E735 Collaboration T.Alexopoulos et al., Phys. Lett. B336 (1994) 599. • Strong multiplicity dependence of high pT spectrum • Sensitivity of Y(z) to parameter c: z ~ (dN/dη)–c

  34. STAR c=0.25 Multiplicity independence of Z-scaling at RHIC Charged hadron spectra vs. dNch/dh in pp collisions from STAR • Sensitivity of cross section to multiplicity density at high pT • Self-similarity & fractality are reflected in processes with high multiplicities in pp and pp collisions at high pT ¯ Independence of heat capacity c on energy and multiplicity over a wide pT range is confirmed by UA1, E735, CDF and STAR data. STAR Collaboration J.E.Gans, PhD Thesis, Yale University, USA (2004). M.T., I.Zborovsky hep-ph/0506003

  35. The same asymptotics for pp & pp at low z • Coincidence of Ψ(z) in the overlapping range • Power law, Ψ(z) ~ z–β, at high z • <pT> dependence vs. dNch/dη and energy s1/2 ¯ • The same asymptotics for pp & pp at low z • Coincidence of Ψ(z) in the overlapping range • Power law, Ψ(z) ~ z–β, at high z • z-pTplot & kinematical region to search for new physics • <pT> dependence vs. multiplicity dN/dη and energy s1/2 ¯ Z-scaling at RHIC Multiplicity dependence ofcharged hadron spectra in pp collisions Z-scaling at RHIC Multiplicity dependence ofcharged hadron spectra in pp collisions E735 Collaboration, T.Alexopoulos et al., Phys. Lett. B336 (1994) 599. STARCollaboration, J.E.Gans, PhD Thesis, Yale University, USA (2004).

  36. STAR preliminary A.Suaide RHIC p0 spectrum Z-scaling is manifestation of principles Self-similarity &Fractality collective phenomena ? ? substructure Structure of colliding objects (hadrons and nuclei), constituent interactions and mechanism of particle formation reveal self-similarity and fractality over a wide scale range. Established properties could give new constraints on phenomenological models and mechanisms of particle production. pp data is a reference for search for new physics phenomena in hadron and nucleus interactions at high energies. Translation & Dilatation

  37. Summary Z-scaling is specific feature of high-pT particle production established in pp and pp collisions. Z-scaling isobserved in numerous high-pT data obtained at the U70, ISR, SppS, Tevatron and RHIC. New data on particle (h±,π,η,0,KS,K*,φ, Λ, Ξ,γ) spectra obtained in pp collisions atRHIC were analyzed. Confirmation ofZ-scalingis obtained. Multiplicity independence of Z-scaling is established. Predictions of high-pT particle cross sections at RHIC energies are presented. ¯ ¯ Z-scaling gives possibility to study self-similarity and fractality and search for new symmetries related to structure of particles and space-time at small scales. Z-scaling is a tool tosearch for new phenomena in high-pT and high multiplicityparticle production in pp & pp collisions at the RHIC, Tevatron and LHC ¯

  38. Thank You for Your Attention We are grateful for fruitful collaboration to our collegues Yu.Panebratsev, G.Skoro, O.Rogachevsky, T.Dedovich, D.Toivonen

  39. Back-up slides

  40. Jets at Tevatron in Run II CDF & D0 data are described by NLO QCD very well CDF & D0 confirm Z-scaling M. T. T. Dedovich Int. J. Mod. Phys. A15 (2000) 3495 Don Lincoln (for the DØ & CDF collaborations) “XXV Physics in Collision 2005”, 6-9 July, 2005, Prague, Czech Republic

More Related