Physics at a  low energy  collider Steve Asztalos LLNL

Steve Asztalos - LLNL2 The basic idea…

Steve Asztalos - LLNL3 Compelling physics case for a photon collider at NLC (but is it technically feasible)? Though proposed in 1981, only have recent (laser) developments made it possible to achieve high luminosities. Demonstration prototype at an existing e + e - machine. Technical requirements: -Lasers: ~ 1  m, rep rate ~ 10 Hz, 0.1 J, 2 ps -Optics: /50, diffraction limited, focus and alignment -Mechanical: Beam line, tight tolerances

Steve Asztalos - LLNL4 LLNL has demonstrated the individual technologies Mechanical System Optics Assembly Interferometric Alignment Optics System 0.1J x 2 x 30Hz, 6W average power laser OPCPA LASER System

Steve Asztalos - LLNL5 Assemble subsystems at a test facility Would demonstrate essential elements of an NLC-like IR

Steve Asztalos - LLNL6 One such suitable facility Beam Energy DR  x,y (m-rad) FF  x,y (m-rad)  x /  y  z  x,y N  30 GeV 1100 / 50  8 / 0.1 mm 0.1 – 1.0 mm 1500/55nm 6.0E9 Rough estimate ~$10M total project cost (incl. manpower) See

Steve Asztalos - LLNL7 A snapshot of the CP ~ 1  m, E  ~ 0.1 J,  x ~ 1.4  m,  y ~ 50.2 nm,  z ~ 0.1mm N  /N e ~ 10 9 Photons receive a maximum of 1/3 of e + e - energy CAIN

Steve Asztalos - LLNL8 This IP would deliver the world’s largest  luminosity… Assuming e + /e - bunch charge of 4x10 10 appropriate for a NLC-like beam a photon luminosity ~ 3x10 32 cm -2 sec -1 could be achieved.  L/  E ~ 4x10 31 cm -2 sec -1 GeV -1 CAIN

Steve Asztalos - LLNL9 …and is verifiable Kinematics allows separation of reaction products. Pandora

Steve Asztalos - LLNL10 -Resonances: -Photon structure function: -Quark models: diquark or three quark -Triangle anomaly and sum rules Budnev, et al., Physics Reports, 15 (1975) 181 A low energy program cc

Steve Asztalos - LLNL11

Steve Asztalos - LLNL12 Status of heavy resonances ~ 100 MeV ? xx

Steve Asztalos - LLNL13 xx Bottom mesons are more challenging ? ? ? ? ?

Steve Asztalos - LLNL14 1S 13S113S1 11S011S0  cc Spin-spin interactions: Spin-orbit interactions: 1P  2 (1 3 P 2 )  1 (1 3 P 1 )  0 (1 3 P 0 ) Meson physics One-gluon exchange plus confinement:

Steve Asztalos - LLNL15 -  c (2s) discovery (1980) reconfirmed only last year at BELLE. Large mass confounds theoreticians (PRL 89, (2002), PRL 89 (16) ) - resonances continue to elude detection. Hydrogen spectroscopy gave us the Bohr atom (Stephen Godfrey, Quarkonium Spectroscopy 2nd International Workshop on Heavy Quarkonium 2003)

Steve Asztalos - LLNL16 Meson production with virtual photons. Take advantage of 10 2 increase in  luminosity. Exploit control over laser polarizations to enhance particular states. For example, circular polarization enhances 0 + (signal) states over 2 + (background) states. Why final states ? - Appreciable BR in resonance decays ~ Simple event reconstruction - Well characterized background We can do better with

Steve Asztalos - LLNL17 Preparing the tools: Physics and Detector Pandora/Pythia: SM and MSSM Event generation Packaged or user-defined luminosity and cross section classes. Delivers parton listing and luminosity-integrated cross section. Partons passed to Pythia for hadronization (as needed) and StdHep formatting sldnt.slac.stanford.edu/nld/new/Docs/Generators/PANDORA.htm LCDROOT: Detector Simulation and Event reconstruction Track smearing Reconstruction of invariant mass Fitting sldnt.slac.stanford.edu/nld/New/Docs/LCD_Root/root.htm

Steve Asztalos - LLNL18 Luminosity: User-defined luminosity based on CAIN. 4 x array of photon weights sorted by energy and helicity. Physics: Define new resonance classes. Decay mesons to massive final states. Pandora’s luminosity integrated cross section not reliable for very narrow widths (< 10 MeV). Override randomly generated final states. Interface: Identification of intermediate and final states in event structure Pandora modifications for

Steve Asztalos - LLNL19 Pandora Luminosity Modification for Built-in Pandora luminosity class adequately treats Compton-backscattering process… …but does not include multiple interactions nor beamstrahlung.

Steve Asztalos - LLNL20 Real photons only have transverse polarizations (helicity {1,-1}). Associating luminosity with mesons For L =1 Clebsch-Gordan coefficients give the (9) possible product states.

Steve Asztalos - LLNL21 Pandora Physics Modifications for background cross section of interest in resolution of controversy between three quark (Nucl. Phys. B 259, (1985) 702) and diquark hadron models (Phys. Lett. B 316, (1993) 546). Both models predict For our purpose, is background whose functional behavior scales as Chen-Cheng Kuo, Photon Frascati

Steve Asztalos - LLNL22 Breit-Wigner Signal with Power Law Background No. of signal events: No. of background events:

Steve Asztalos - LLNL23 Event numerology Mass Γ γγ/ Γ tot Γ tot Events  c (1S) x  c (2S) x10 -4(1) * (2) 2643  c0 (1P) x x  c2 (1P) x x  b (1S) x10 -4* (Q b M b /Q c M c ) (3 ) (4) < Total15227 (1) Assumed to be same as for  c (1S) for  c (1S) times (1)

Steve Asztalos - LLNL24 Clear meson signals  c (1S)  c (2S)  c0 (1P)

Steve Asztalos - LLNL25 Exploit angular information to suppress background  c (1S)  c (2S)  c0 (1P)

Steve Asztalos - LLNL26 How do we match up? Weiszacker-Williams spectrum

Steve Asztalos - LLNL27 Comparing BELLE and LINX luminosities

Steve Asztalos - LLNL28 Mesons from virtual photons (BELLE results)

Steve Asztalos - LLNL29 Summary Compare events generated by Compton- backscattering with Weizsacker-Williams method Study different mesons decay modes Address effects of laser and electron polarizations Still to come… Charmed mesons should be copiously produced at a  collider. This would allow for detailed studies of their properties.