Hadron Physics with Antiprotons

Transcription

1 Hadron Physics with Antiprotons Introduction HESR/PANDA - Project at GSI ( W. Henning) Merits of experiments with antiprotons Physics Program Charmonium Spectroscopy ( D. Bettoni) Heavier Glueballs and charmed Hybrids ( K. Peters) Hadrons in Nuclear Matter ( W. Henning) Double Hypernuclei ( J. Pochodzalla) Further Options: Low energy beams, Open Charm production, CP-Violation, Inverted Deeply Virtual Compton Scattering ( P. Kienle, Poster H. Koch, S. Ganzhur) Status of the Project Conclusions

2 Introduction Open problems in non-perturbative QCD Confinement Violation of chiral symmetry Masses of Hadrons Important : Gluonic degrees of freedom

3 Layout of proposed new GSI facility p-beam p-beam

4 HESR (High Energy Storage Ring) p production with 29 GeV p-beam p production rate : 10 7 /s p-stored in the HESR, Fixed Target (E CM 5.5 GeV) p-momentum : GeV/c N p-stored : High luminosity mode L cm -2 s -1 δp/p 10-4 (stochastic cooling) PANDA-Detector BILD fehlt Woher? High resolution mode L cm -2 s -1 δp/p 10-5 (e - cooling)

5 The PANDA detector Detector features: tracking of charged particles measurement and identification of g, e±, m±, p±, K±, p, p high rate capability sophisticated and fast trigger scheme

6 PANDA Detector Detector requests Nearly full solid angle for charged particles and Gammas High rate capability Good particle identification (e, µ, π, K, p) Efficient trigger on e, µ, K, D General purpose detector Target: Jet/Pellet/Wire Tracking: Pixels (MVD) / Straws / Mini-Drift-Chambers (MDC) E.M. Calorimeter: PbWO 4, APD-Readout Muons: Plastic Scint. Strips PID: Aerogel Cerenkov (ACC) / DIRC Trigger: 0 High p electrons/muons / Multiplicity jump (K S, Λ, ) Secondary vertex (D s, ) / Invariant masses / Global kinematical conditions

7 QCD systems to be studied at HESR QCD systems to be studied at HESR

8 Review of Particle Physics 2000 N 2S+1 L J J PC ud, uu, dd uu, dd, ss su, sd I = 1 I = 0 I = 1/2 1 1 S π η, η' K 1 3 S 1 1 ρ ω, φ K*(892) 1 1 P b 1 (1235) h 1 (1170), h 1 (1380) K 1B 1 3 P a 0 (1450) f 0 (1370), f 0 (1710) K 0 *(1430) 1 3 P a 1 (1260) f 1 (1285), f 1 (1420) K 1A 1 3 P a 2 (1320) f 2 (1270), f 2 '(1525) K 2 *(1430) 1 1 D π 2 (1670) η 2 (1645), η 2 (1870) K 2 (1770) 1 3 D 1 1 ρ(1700) ω(1650) K*(1680) 1 3 D 2 2 K 2 (1820) 1 3 D 3 3 ρ 3 (1690) ω 3 (1670), φ 3 (1850) K 3 *(1780) 1 3 F a 4 (2040) f 4 (2050), f 4 (2220) K 4 *(2045) 2 1 S π(1300) η(1295), η(1440) K(1460) 2 3 S 1 1 ρ(1450) ω(1420), φ(1680) K*(1410) 2 3 P f 2 (1810), f 2 (2010) K 2 *(1980) 3 1 S π(1800) η(1760) K(1830) contributions from LEAR experiments

9 HESR / PANDA Production Rates (1-2 (fb) -1 /y) Final State cross section # reconstr. events/y Meson resonance + anything 100µ b ΛΛ 50µ b DD 250nb 10 J/ ψ ( e e, µ µ ) 630nb 10 χ ( J/ ψ+ γ) 37. nb 10 2 c c c c nb nb ΞΞ( A) 2µ b 10 ( 10 ) ΛΛ ΩΩ ΛΛ Common Feature : Low multiplicity events Moderate particle energies For Pairs : Charge symmetric conditions Trigger on one, investigate the other

10 Merits of experiments with Antiprotons High cross sections Facilitates search for rare particles (Glueball Groundstate) Most particles can be directly created in formation processes regardless of their J PC quantum numbers (cc-spectroscopy) Exotic states are produced with rates similar to qq, qqq-systems (Glueball-, Hybrid candidates) (Cooled) beams have small p/p and small emittances Clean experimental conditions p-induced reactions ( 15 GeV) have low particle multiplities Reconstruction of full events, Reliable PWA

11 3 712,000 events pp π ο π ο π ο (at rest) f 2 (1565) pp π ο ηη (at rest) m π ο π ο 1 2 m ηπ ο m π ο π ο 2 3 GeV GeV 2 2 m ηπ ο events f 0 (1500) m 2 (π 0 K L seen ) 1.8 f o (1500) K L K L pp π o K L K L GeV 2 m 2 (π 0 K L miss ) 6000 CB Data pp 5 π 3.0 pp π ηη' M 2 ηη 2000 Phase Space M 4π ο GeV 2 M 2 πη

12 Charmonium - States Merits of experiments with Antiprotons e + e - collisions: Only 1 -states are directly formed (Well measured, e e + energy scans) The other states only visible through secondary reactions, e.g.: e + e ψ χ + γ (moderate mass resolution) pp - collisions: All states can be directly formed (Very good mass resolution, scans with p)

13 LEAR : Spin Exotics Merits of experiments with Antiprotons + 0 pstop d X( 1 ) + π+ p, X( 1400) ηπ, ηπ ; X( 1600) πη General observations High Statistics data needed Exotics couple to pp with a strength similar to qq-states (Established by BNL; First hints: VES, GAMS) Number of events a 2 (1320) π 1 (1400) m πη [GeV 2 /c 4 ]

14 Properties of the ρ(1400) Decay: (ηπ) L=1 Mass: 1400 ± 30 MeV Width: 310 ± 70 MeV Quantum Numbers: J PC = 1 + (I =1) not possible from qq J = L + S P = ( ) L+1 C = ( ) L+S Previous indications of this resonance: π p (π η)n (GAMS/CERN, 100 GeV/c, 1988) π p (π η)n (VES/Serpukhov, 100 GeV/c, 1993) π p (π η)n (E852/Brookhaven, 18 GeV/c, 1997) M: MeV, G: MeV

15 A second exotic particle (J PC =1 + ) Crystal Barrel: pp π + π η' π 1 (1600): M = 1563 ± 30 MeV/c 2 Γ = 195 ± 50 MeV/c 2 preliminary, LEAP2000 conference BNL (E852): π p ρπ p π 1 (1600): M = 1593 ± 8 MeV/c 2 Γ = 168 ± 20 MeV/c 2 Phys. Rev. Lett. 81 (1998) 5760

16 Fit of Dalitz plot preliminary, Joerg Reinhardt, Bonn ()S a2 (1320) a 0 (1450) 1 lnl (1585,160) (1567.7,158.2) (1563,195.0)

17 Meson production in D s decays with BABAR ~ 900 events in 1 year of running

18 New Results from CLEO B J/ψφK Phys. Rev. Lett. 84, 1393 (2000) M 2 (J/ )(GeV 2 /c 4 ) GeV/c GeV/c GeV/c M 2 ( K)(GeV 2 /c 4 ) Indications for a J/ψφ resonances? BABAR can expect ~300 events within 5 years.

19 Physics Program / Charmonium Spectroscopy cc - system (QCD) =^ e + e -system (QED) Energies/Energy splittings/widths of states Details of QQ-interactions Confinement Potential Exclusive Decays Mixing of perturbative/non-pert. effects

20 Physics Program / Charmonium Spectroscopy Experimental situation R704 (CERN/ISR) / E760/835 (Fermilab) Discovery of h c ( 1 P 1 ) - state Very precise values for masses and withs of χ c, η c -states Measurement of previously unknown branching ratios Determination of α s (m c ) But : Severe limitations (Non magnetic detector, beamtime, beam momentum reproducibility,...) Many questions left open: η c (Cball) not yet established (Spin-Spin-Interaction) 1 P 1 (E760) unconfirmed D-wave states (some of them very narrow) and radially P-states not fully understood (Structure of states) Angular distributions of radiative decays not understood (Mixing of pert./non-pert. Effects) 0 e.g. J/ ψ ρπ ; ηc, χco BB (Hadron helicity non conserving process) + 0 J / ψ π π, ωπ, ρη (G parity violating decays) ψ γ+ π, η... (Radiative ψ decays) χ ρρ, φφ, ρη, ρη, ηη (Higher Fock state contributions) cj

21 Charmed Hybrids : (ccg) Physics Program / Charmed Hybrids Predictions: (LQCD, Bag-Model, Flux-Tube-Model, ) Masses Lowest energy states: GeV/c 2 Ground state: J PC = 1 + (spin-exotic) Widths Could be narrow in some cases ( MeV)

22 Physics Program / Charmed Hybrids High chances to find charmed hybrids Less mixing than in (qqg)-sector Measuring program at HESR States with non exotic q.-n.: p-scan: pp (ccg) GeV/c 2 ; J/ψ-trigger) pp (ccg) ( GeV/c 2 ; D-trigger), 10 4 (ccg) J/ψ + η per day (Decay channel selects q.-n.) States with exotic q.-n.: Production experiment: pp ( ccg) + π0( η) J/ ψ+ ω, φ, γ 10 2 (ccg) per day, PWA of Dalitz-Plots (see LEAR) In addition: Measuring program on light hybrids 2 GeV/c 2, Scan- and production mode Favorite channels: pp ( ccg) f1( 1285) π, K1K,... Large cross sections (µb), Complementary to Hall D

23 Glueballs (gg) Predictions: Physics Program / Heavier Glueballs Masses: GeV/c 2 (Ground state found? ; Candidates for further states?) Quantum numbers: Several spin exotics (oddballs), e.g. J PC = 2 +- (4.3 GeV/c 2 ) Widths: 100 MeV/c 2 Decay into two lighter glueballs often forbidden because of q.-n. No mixing effects for oddballs

24 Charmonium States and Predicted Glueballs Charmonium [MeV] J PC UKQCD Collaboration, G. S. Bali et al., Phys. Lett. B309 (1993) 378. C. Morningstar, M. Peardon; Phys. Rev. D 60 (1999)

25 Physics Program / Heavier Glueballs Production cross section: Maybe high in pp-annihilation (see f 0 (1500)) Comparable to qq-systems (! µb) Experimental program at HESR p-scan for non-exotics: pp (gg) φφ, φη (Most reasonable channels, easily distinguishable, low l - waves (simple PWA)) Production exp. for exotics: pp (gg) + π Reasonable measuring times

26 Physics Program / Measurements in the Charm Region Spin non exotic states X : pp X ( p scan) X : Heavier qq mesons nπ + mk,... Heavier Glueballs φφ, φη,... Charmed Hybrids J/ ψη,... Spin exotic states (# qq) Y: pp Y + π, η,... (Production mod e) Y : Oddballs Charmed Hybrids ηπ, φφ,... χππ ( ),... ( e. g. groundstate) s

27 Physics Program / Hadrons in Nuclear Matter 1) Effective masses of hadrons in the nuclear medium 206 Pb(d, 3 He), Q-Value K +, K -Production in heavy ion collisions Excitation spectra (m K ) Eff.

28 Physics Program / Hadrons in Nuclear Matter Effective D-masses in nuclear medium Dramatically increased DD-decay rate of ψ - and χ C2 -states in nuclear medium Substantial increase of widths (0.3 MeV?; 2.0 MeV?) Increased width of ψ(3770) (24 MeV?)

29 Physics Program / Hadrons in Nuclear Matter 2) J/ψ - nucleon absorption cross section Important for J/ψ - suppression in QGP Proposed reaction: p( GeV/c) + A J/ψ + (A-1) Furthermore: cc - dissociation to open charm in the presence of nucleons: pd D + Λ+ c Elastic J/ψ - nucleon cross sections (Low momenta) pd J /ψ+ γ+ n

30 Physics Program / Double Hypernuclei 3) Strange Baryons in Nuclear Field Hypernuclei = Third dimension of the nuclear chart Production of Double Λ-Hypernuclei: p( 26. GeV/ c) + A Ξ (slow) + Ξ( KK ); Ξ (slow) + A ΛΛ A Trigger Active, secondary target

31 Baryon Spectroscopy Physics Program / Further Options New states, Quantum numbers and decay rates Rare D-decays Example: + + D µν( BR ~ 10 4 ) Γ ~ f ~ ψ( 0) Direct CP-Violation in Λ, Λ-decays Compare angular decay asymmetries Sensitive Test of LQCD, ( αα, ) for Λ pπ / Λ pπ + α A + α α α Prediction (SM) 2x10-5 HESR: 1 year of beamtime

32 Physics Program / Further Options CP-Violation in charmed region D / D Mixing ( r) < 10 ( SM) HESR : r/ r~ Direct CP-Violation (SCS) Compare D K K * / D K K * Asymmetries A ( SM) < HESR = A/ A

33 Physics Program / Further Options Study of reversed Deeply Virtual Compton Scattering (DVCS) p+ p γ* + γ ll + + γ Nucleon structure functions Low energy p-physics pp-annihilation process Antiprotonic atoms Antihydrogen

34 Status of the Project May 1999 Jan Nov July 2002 Nov Jan : LOI for HESR ( : Start of Detector simulations (Geant 4) : Conceptual Design Report ( Review by an International Committee of the Deutsche Wissenschaftsrat : First Meeting of the PANDA collaboration (35 Institutions, 160 scientists so far) : Very positive vote of the Deutsche Wissenschaftsrat Start of R&D work for the PANDA detector : Promise for funding of the project by the German Ministery for Research and Technology

35 Conclusion HESR will deliver cooled high quality antiproton beams with energies up to 15 GeV Antiproton induced reactions exhibit unique features High statistics data Low multiplicity events Symmetric production of particles and antiparticles High production rates for gluonic hadrons Many states can be directly formed Rich and unique Physics Program with emphasis on charmed particles Precision charmonium spectroscopy Search for charmed hybrids and heavier Glueballs J/ψ-Nucleon interactions Effective masses of hadrons in nuclear matter CP-violation in the charm sector Low energy p - physics, including Antihydrogen experiments