Hefei, September 2015

Transcription

1 Status of MC generators for low energy e + e scattering H. CZYŻ, IF, UŚ, Katowice, 10th International Workshop on e + e collisions from φ to ψ Hefei, September 2015

2 Outline Monte Carlo generators for luminosity Monte Carlo generators for scan Monte Carlo generators for γ γ Monte Carlo generators for radiative return Progress on PHOKHARA generator Radiative corrections Summary UŚ, Katowice, Hefei, September 2015 Status of MC generators at low energy, 2

3 BHWIDE MC for e + e e + e -luminosity YFS exponentiation Phys.Lett. B390 (1997) [S. Jadach, W. Placzek and B. Ward] MCGPJ ISR, structure functions, e + e, µ + µ, π + π,k + K, K 0 K 0 [A. Arbuzov, G. Fedotovich, F. Ignatov, E. Eur.Phys.J. C46 (2006) Kuraev and A. Sibidanov] BABAYAGA@NLO Nucl. Phys. B758(2006) parton showers, NLO,NNLO [G. Balossini, C. M. Carloni Calame, G. Montagna, O. Nicrosini and F. Piccinini] UŚ, Katowice, Hefei, September 2015 Status of MC generators at low energy, 3

4 KKMC MC for e + e hadrons(muons) ISR,YFS exponentiation, muons, hadrons [ S. Jadach, B. Ward and Z. Was] Comp.Phys. Comm. 130(2000) 260;Phys. Rev. D 63(2001) MCGPJ ISR, structure functions, e + e, µ + µ, π + π,k + K, K 0 K 0 Eur.Phys.J. C46 (2006) [A. Arbuzov, G. Fedotovich, F. Ignatov, E. Kuraev and A. Sibidanov] PHOKHARA 8.0 JHEP08(2013)110. ISR, fixed order (NNLO), muons, hadrons [H.Czyz, M. Gunia, J.H. Kuhn] UŚ, Katowice, Hefei, September 2015 Status of MC generators at low energy, 4

5 MC for e + e hadrons(muons) LUARLW adopted LUND model [ H. Hu, B. Anderson] hep-ph/ ZRC structure functions, narrow resonances [D. Zhang, G. Rong, J.C. Chen] Phys.Rev. D74 (2006) carlomat 3.0 CPC(2015)563. LO, CHPT, multi-hadronic states, ISR,FSR,automatic code generation [K.Kolodziej] UŚ, Katowice, Hefei, September 2015 Status of MC generators at low energy, 5

6 MC for γ ( ) γ ( ) no name e + e e + e π 0 π 0, DAPHNE energy [F. Nguyen,F.Piccinini,A.D.Polosa] Eur.Phys.J. C47 (2006) 65 TwoGam?? [D.Coffman, V.Savinov] CLEO TREPS KEK-REPORT-96-11, arxiv: equivalent photon approximation [S. Uehara] UŚ, Katowice, Hefei, September 2015 Status of MC generators at low energy, 6

7 MC for γ ( ) γ ( ) GALUGA e + e e + e X, LEP energy [G.A.Schuler] Comput.Phys.Commun. 108 (1998) 279 EKHARA exact matrix element at LO [H.Czyz,S.Ivashyn,E.Nowak] Comput.Phys.Commun. 182(2011) 1338 GGRESRC Comput.Phys.Commun. 185 (2014) 236 approximated radiative correction [Druzhinin, V. P. and Kardapoltsev, L. V. and Tayursky, V.A.] UŚ, Katowice, Hefei, September 2015 Status of MC generators at low energy, 7

8 THE RADIATIVE RETURN METHOD dσ(e + e hadrons + γ(isr)) = H(Q 2,θ γ ) dσ(e + e hadrons)(s = Q 2 ) measurement of R(s) over the full range of energies, from threshold up to s large luminosities of factories compensate α/π from photon radiation radiative corrections essential (NLO,...) High precision measurement of the hadronic cross-section at meson-factories UŚ, Katowice, Hefei, September 2015 Status of MC generators at low energy, 8

9 EVA: e + e π + π γ tagged photon (θ γ > θ cut ) ISR at LO + Structure Function FSR: point-like pions [Binner et al.] e + e 4π + γ ISR at LO + Structure Function [Czyż, Kühn,2000] MC generators needed PHOKHARA 9.1: π + π, µ + µ, 4π, NN, 3π, KK, Λ( ) Λ( ), J/ψ,ψ(2S) ISR at NLO: virtual corrections to one photon events and two photon emission at tree level γ γ 2 γ 2 γ + + H.C., A. Grzelińska, M. Gunia, J. H. Kühn, E. Nowak-Kubat, G. Rodrigo, Sz. Tracz, A. Wapienik FSR at NLO:π + π, µ + µ,k + K, pp tagged or untagged photons e + e hadrons (muons) ISR at NNLO Modular structure UŚ, Katowice, Hefei, September 2015 Status of MC generators at low energy, 9

10 MC for radiative return e + e 4π + γ ISR at LO + Structure Function [Czyż, Kühn] e + e hadrons + γ upgraded by BaBar - AfkQED not public PHOTOS [Barberio et al.] for FSR EVA: e + e π + π γ tagged photon (θ γ > θ cut ) ISR at LO + Structure Function FSR: point-like pions [Binner et al.] e + e π +,0 π,0 + γ FASTERD: FSR studies [Pancheri,Shekhovtsova,Venanzoni] UŚ, Katowice, Hefei, September 2015 Status of MC generators at low energy, 10

11 Modest progress on PHOKHARA H.Czyz, J.H.Kuhn, Sz. Tracz, Phys.Rev. D90 (2014) 11, Nucleon form factors - new model FSR corrections for pp H.Czyz, J.H.Kuhn, Sz. Tracz, in preparation χ c1 and χ c2 production in e + e UŚ, Katowice, Hefei, September 2015 Status of MC generators at low energy, 11

12 Nucleon form factors - new model F p 1,2 = Fs 1,2 +Fv 1,2 F1,2 n = Fs 1,2 Fv 1,2 F1 s = 1 Nn=0 c 1 n BW ω n (s) 2 Nn=0 c 1, n F1 v = 1 Nn=0 c 2 n BW ρ n (s) 2 Nn=0 c 2, n Nn=0 F2 s = 1 2 b c 3 n BW ω n (s) Nn=0 c 3, n F2 v = 1 Nn=0 2 a c N n BW ρ n (s) Nn=0 c N, n UŚ, Katowice, Hefei, September 2015 Status of MC generators at low energy, 12

13 Nucleon form factors - new model G. P. Lepage and S. J. Brodsky, Phys.Rev. D22, 2157(1980). F 1 1 (Q 2 ) 2, F 2 1 (Q 2 ) 3, BW i (Q 2 ) = m 2 i m 2 i Q2 im i Γ i θ(q 2 ). c j i = cjr i + ic ji i θ(q2 ) UŚ, Katowice, Hefei, September 2015 Status of MC generators at low energy, 13

14 Phys.Rev. D90 (2014) 11, fit, N=4 χ 2 = 124 for 150 data points and fitted 20 parameters UŚ, Katowice, Hefei, September 2015 Status of MC generators at low energy, 14

15 Data vs. fit σ(e + e pp) (pb) BaBar FENICE DM2 DM1 Adone BES CLEO fit s (GeV) UŚ, Katowice, Hefei, September 2015 Status of MC generators at low energy, 15

16 Data vs. fit PS170 BaBar fit G p E / Gp M Q 2 (GeV) UŚ, Katowice, Hefei, September 2015 Status of MC generators at low energy, 16

17 Data vs. fit FENICE fit σ(e + e nn) (pb) s (GeV) UŚ, Katowice, Hefei, September 2015 Status of MC generators at low energy, 17

18 Data vs. fit JLab 05 JLab 02 JLab 01 MAMI 01 JLab 10 fit µpg p E /Gp M Q 2 (GeV 2 ) UŚ, Katowice, Hefei, September 2015 Status of MC generators at low energy, 18

19 Radiative corrections ISRNNLO ISRNNLO*CF σ(e + e pp) (nb) o < θ p, p < 160 o s(gev) UŚ, Katowice, Hefei, September 2015 Status of MC generators at low energy, 19

20 FSR modelling - few remarks typical corrections - beyond CF are small and not under control σ(isr+fsr)/ σ(isr CF) Q 2 (GeV) s = 2.5GeV 20 o < θ p, p,γ < 160 o UŚ, Katowice, Hefei, September 2015 Status of MC generators at low energy, 20

21 FSR modelling - problems 2 form factors for on shell particles modelling of transition form factors necessary it has to be addressed together with ep ep Conclusions for pragmatic reasons further FSR modelling postponed till UŚ, Katowice, Hefei, September 2015 Status of MC generators at low energy, 21

22 χ c production in e + e UŚ, Katowice, Hefei, September 2015 Status of MC generators at low energy, 22

23 χ c production in e + e φ inter φ max φ min rad. ret without Int σ (nb) o < θ µ,µ + < 160 o M χc1 = GeV s(gev) UŚ, Katowice, Hefei, September 2015 Status of MC generators at low energy, 23

24 NLO-IFS Included for muons and pions UŚ, Katowice, Hefei, September 2015 Status of MC generators at low energy, 24

25 How big are the corrections NLO-ISR-FSR UŚ, Katowice, Hefei, September 2015 Status of MC generators at low energy, 25

26 NLO-ISR vs. SF Structure functions to be used carefully UŚ, Katowice, Hefei, September 2015 Status of MC generators at low energy, 26

27 NLO-asymmetries Campanario, F. and Czyż, H. and Gluza, J. and Gunia, M. and Riemann, T. and Rodrigo, G. and Yundin, V. JHEP 1402 (2014) 114 UŚ, Katowice, Hefei, September 2015 Status of MC generators at low energy, 27

28 NLO-asymmetries Campanario, F. and Czyż, H. and Gluza, J. and Gunia, M. and Riemann, T. and Rodrigo, G. and Yundin, V. JHEP 1402 (2014) 114 UŚ, Katowice, Hefei, September 2015 Status of MC generators at low energy, 28

29 To be done in PHOKHARA PH: get the complete NLO for pions in progress PH: improve efficiency in muon mode PH: add NNLO corrections for ISR UŚ, Katowice, Hefei, September 2015 Status of MC generators at low energy, 29

30 Conclusions IN PROGRESS... critical mass of number of people working on Monte Carlo and radiative corrections not reached... but we keep working UŚ, Katowice, Hefei, September 2015 Status of MC generators at low energy, 30