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Cross section e + e - -> wp 0 -> p 0 p + p - p 0

Cross section e + e - -> wp 0 -> p 0 p + p - p 0. Antonio De Santis Simona Giovannella. w. w. r,r ’. f. p 0. p 0. Amplitude: how to measure BR( f->wp 0 ). f contribution in cross section could be represented as interference with continuum process r->wp.

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Cross section e + e - -> wp 0 -> p 0 p + p - p 0

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  1. Cross section e+e--> wp0 -> p0p+p-p0 Antonio De Santis Simona Giovannella A.De Santis Radiative Meeting 28/04/06

  2. w w r,r’ f p0 p0 Amplitude: how to measure BR(f->wp0) f contribution in cross section could be represented as interference with continuum process r->wp. Interference is parametrized by term (Z) at f-resonace peak. A.De Santis - Radiative Meeting 28/04/06

  3. p0 (p3) p+ (p1) r w p- (p4) p0 (p2) Amplitude: MC generator Reference: hep-ex/9904024 v2 All term which differs for exchange between two p0’s or different r charge must be summed. Resulting matrix element (M) could be expressed as modulus squared of current composed by two term(p0’s permutation) each composed by tree terms (r charge) A.De Santis - Radiative Meeting 28/04/06

  4. Analisys strategy • Acceptance • One vertex at Interaction Point (IP) • Two tracks connected at vertex • Four neutral cluster with: • Eclu grater than 10 MeV • ToF compatible with prompt g • |cos(q)| < 0.93 • Kinematic Fit • Fine selection: • c2 < 50 • Dmp/mp < 3s • Slice dataset in function of ECM • Signal events counting (fit via HMCMLL) • Cross section fit A.De Santis - Radiative Meeting 28/04/06

  5. Data vs MC: p0 recoil mass old MC new test MC Left side: data(2001+2002) fitted with old self-made MC production. Right side: data(2002) compared with new MC test production (100pb-1 all_phys LSF 0.2) A.De Santis - Radiative Meeting 28/04/06

  6. Data vs MC: cos(q)p0 old MC new test MC Left side: data(2001+2002) fitted with old self-made MC production. Right side: data(2002) compared with new MC test production (100pb-1 all_phys LSF 0.2) A.De Santis - Radiative Meeting 28/04/06

  7. Data vs MC: cos(q±) old MC new test MC Left side: data(2001+2002) fitted with old self-made MC production. Right side: data(2002) compared with new MC test production (100pb-1 all_phys LSF 0.2) A.De Santis - Radiative Meeting 28/04/06

  8. Data vs MC: M(p+p-) old MC new test MC Left side: data(2001+2002) fitted with old self-made MC production. Right side: data(2002) compared with new MC test production (100pb-1 all_phys LSF 0.2) A.De Santis - Radiative Meeting 28/04/06

  9. Analysis Efficiency (MC) 0.472 ± 0.005 0.422 ± 0.006 0.894 ± 0.003 A.De Santis - Radiative Meeting 28/04/06

  10. Systematic errors: counting contribution Preliminary • Possible source of systematic error in counting: • Luminosity factor; • Trigger efficiency; • Clustering efficiency; • Resolution effect on acceptance cut. All these effects are summed with counting fit error. A.De Santis - Radiative Meeting 28/04/06

  11. Cross section fit Preliminary Fit result: Radiative correction for the cross section are calculated through convolution with radiator function at fit level. A.De Santis - Radiative Meeting 28/04/06

  12. Systematic errors: impact of fine cut and counting variable Systematic errors are evaluated as r.m.s. of fit-parameter distribution obtained varying value for angular coefficient B in cross section function and varying counting-fit distribution. A.De Santis - Radiative Meeting 28/04/06

  13. SPARE A.De Santis - Radiative Meeting 28/04/06

  14. Amplitude current term Form factor Inverse propagator A.De Santis - Radiative Meeting 28/04/06

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