1 FAIR SIMULATION ACTIVITIES AND PHENOMENOLOGICAL STUDIES AT IPN ORSAY PANDA Collaboration Meeting, GSI, Sep. 5, 2011 Béatrice Ramstein for the French PANDA team

2  Motivations: electromagnetic processes Feasibility studies for proton Time-Like electromagnetic Form Factor measurements Trigger developments  Examples of contributions to PANDAroot generators, PID, PANDAgrid  Future plans (to do list)

3  Mixed team of experimentalists and phenomenologists T. Hennino, R. Kunne, D. Marchand, S. Ong, B. R., E. Tomasi-Gustafsson, J. Van de Wiele (IPNO). H. Fonvieille (LPC-Clermont-Ferrand). J. Boucher (PhD ), A. Dbeyssi (PhD ), T. Liu (post-doc 2011), B. Ma (PhD ), M. Sudol (post-doc )  Collaborations: IPNO (J.P. Lansberg), Ecole Polytechnique (B. Pire) GSI – Mainz (F. Maas et al.) Torino (S. Spataro) and Ferrara (S. Pacetti) Karkhov (G. Gakh) and Dubna (E. Kuraev)

4 Proton electromagnetic form factors No data Low quality data Precise but contradictory data q2q2 p p p p γ(q) e+e+ Г μ (q) complex FFs real FFs q 2 < 0 q 2 = s q 2 > 4m p 2 pp  e + e - annihilation - e-e- Space Like (SL) Time Like (TL) Unphysical region p p → e + e - π 0 | Vector meson poles: q 2 = m 2 , m 2 , m 2   Vector Meson Dominance (VMD) form factor models can be tested test pQCD asymptotic behaviour 4m p 2 0

Goal of PANDA measurements ** e+e+ e-e- ee q2q2 e+e+ p p °° e-e- + exch. - Extract Time-Like |G E | and |G M | for proton up to q 2 =14 (GeV/c) 2 from e  angular distributions and G eff up to q 2 =30 (GeV/c) 2 from total cross-sections large q 2 e+e+ p p °° e-e- + exch. - small t e+e+ p p - e-e- proton FF p  TDA p p → e + e - | q 2 <4m p 2 proton form factors in the « unphysical » region from e  angular distributions High q 2 : p->  Transition Distribution Amplitude (TDA) from cross-sections at forward/backward  ° CM angles p p → e + e -  ° |

full-scale simulations in BaBar framework Physics Book+ Sudol et al. EPJA 44 (2010) 373 generators + efficiency/acceptance matrices J. Boucher’s PhD needed tools to continue these studies in PANDAroot - generators for, and background - e  /   PID, matching between detectors - tracking for e  -  ° reconstruction Two major challenges: precision on angular distribution to extract G E /G M (especially at large q 2 ) Huge hadronic background,  (pp  +  - X) /  (pp  e + e - X) ~10 6 p p → e + e - π 0 | p p → e + e - | Feasibility studies for proton Time-Like form-factor measurements || p p → e + e - | p p → e + e - π 0 |

7 Generators for physics analysis with PANDAroot

: generators  Generator for electron angular distributions EvtElectronPositron (EvtGen)  Differential cross-sections for polarized reaction (Jacques Van de Wiele, Egle Tomasi-Gustafsson) Phys.Rev. C83 (2011) p p → e + e - | |  p p →  +  - (main background) s < 6 (GeV/c) 2 : Legendre polynomial fits s > 6 (GeV/c) 2 : counting rules (Ong et Van de Wiele, IPNO-DR-08-01) or Regge trajectories (idem, EPJA46 (2010) 291). (used by M. Zambrana, Mainz) | G eff

 signal  background ** e+e+ ee d  /d  e d  /d  e  e+ (deg)  e+ (deg) : generators Calculation by J. Van de Wiele et al., very general form q2q2 e+e+ p p °° e-e- + exch. - pp   +  -  0 - Effective lagrangians: 3 production mechanisms: non-resonant, ρ and f 2  d 5  p p → e + e - π 0 | J. Boucher PhD Fitted on LEAR data p e-e-  +  - inv. mass Fixed   °,   °

Event generators with radiative corrections  studies of the PHOTOS package (A.Dbeyssi, M. Gumberidze, E. Tomasi-Gustafsson)  Calculation for and including vacuum polarization (J. Van de Wiele and S. Ong) comparison with Photos Effects of proton radiation  Egle Tomasi-Gustafsson: PRD82:094016, 2010 PRC83:025202,2011 p p → e + e - | | p p → e + e -  ° | p p → e + e - π 0 |

Parametrization of cross-sections Total,elastic pion productionNN+pions A. Dbeyssi et al. PANDA Note 2011 Applications: background estimates, trigger design p p | -

12 simulation/reconstruction Trigger studies e/  PID

13 Filter studies for e + e - or e + e -  0 exit channels Fast selection based on EMC info: E max >2.4 GeV and E tot > 4 GeV (R. Kunne and T. Hennino)  +  - 4  ° w/o cut +-4°+-4° Example: p inc =4 GeV/c ~6 σ(pp→6  )~10 mb suppression of  +  - 4  ° -

EMC PID within PANDAroot Distribution of PID probabilities P(GeV/c) E/p = f(p) e - as e -  - as e - Available in PndPidProbability (PndPidEmcBayesAssociator.cc) Next step: include moments of energy distributions in EMC crystals e-e- -- Proba (%) method: (R.Kunne, IPN Orsay) Generate (e ±,p,p,  ±,  ±,K ± ) with flat distributions and reconstruct them (tracking+EMC) For bins in p, θ, calculate probabilities at given E/p for each particle species (e ±,p,p,  ±,  ±,K ± ) from the fitted E/p distributions  Provides EMC PDF for Bayesian PID method - -

 °reconstruction on-going works Use one bump-clusters Exploit cluster shape (moments) use kinematics for dedicated channels e + e -  °,  +  -  0 Efficiency for 2 bump reconstruction Cut on 2  invariant mass R. Kunne  E(GeV) M inv (GeV/c 2 )

Electron tracking Electron tracking with Kalman filter Problem of non-gaussian energy loss for electrons use electron tracking without radiation ? Implement another method (Gaussian Sum Filter)? e tracking with e hypothesis e tracking with  hypothesis Δp/p

Contribution to PANDAGRID PANDAGRID node at IPNO (D. Marchand, C. Diarra, P.-P. Nguyen)

Conclusion and outlook: simulation / analysis activities of the French team  Phenomenology: generators for electromagnetic processes and background : → feasibility studies and trigger developments  Event reconstruction in PANDAroot electron PID with EMC (available in Pandaroot)  ° reconstruction (work in progress) … and still to be studied Detector matching studies Electron tracking ( Kalman filter studies) dE/dx  Further future: feasibility studies with full scale simulations: pp  e + e - (form factors, collaboration with Mainz) pp   +  - (collaboration with Torino) pp  e + e -  ° (form factors and Transition Distribution Amplitude p , collaboration with Mainz) - - -