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Quantification of D 0 cross-feed

Quantification of D 0 cross-feed. J. Bouchet. outline. Use single D 0 with power law p T MuKpi used with “ open cuts”, to not bias the results The misidentified D 0 are reconstructed with (K + ,π - ) (due to PID) then the xfeed is estimated as : # (K + ,π - ) / #(K - ,π + )+#(K + ,π - )

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Quantification of D 0 cross-feed

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  1. Quantification of D0 cross-feed J. Bouchet

  2. outline • Use single D0 with power law pT • MuKpi used with “ open cuts”, to not bias the results • The misidentified D0 are reconstructed with (K+,π-) (due to PID) then the xfeed is estimated as : # (K+,π-) / #(K-,π+)+#(K+,π-) • Study as a function of nsigma(dEdX) of daughters and pT of D0 (at nsigma fixed) • Second part of study is done as a function of cosine(theta*)

  3. Inv. Mass VS ndEdx cut * Green line is a fit using double gaus

  4. (dEdx vs P) VS ndEdx cut

  5. summary *we see from the inv. Mass plots some entries far from the expected D0 mass ; counting in a restricted range to avoid fakes. *Nsigma cut used in 3th production

  6. (dEdx vs P) VS pTD0 cut In this part ,ndEdx is fixed at |ndEdx|<3 for both daughters

  7. Inv. Mass VS pTD0 cut

  8. summary

  9. comments • The xfeed is improved when the cut on the nsigma is tigher : • Obvious since with this cut the PID of daughters is better • It also decreases VS pT of D0 : from slide 6 we see that selecting D0 with pT>2 gives a better PID selection (dEdx band are not overlapping as for pT D0 <0.5) • Next slide : study as a function of cosine(theta*) • Plots of the cosine(theta*) for all entries and fake D0, as a function of reconstructed pT D0

  10. Cosine(theta*) VS pTD0 cut

  11. comments • Slide 10 : we see that the misidentified D0 have a cosine(theta*) distribution reduced [-0.8,0.8] when pT of D0 increases, • whereas the distribution for true D0 remains (in the statistic here) flat over [-1,1] for the pT bins studied here (statistic became low for pT D0>2) • Next slide is just the 2d plots for cosine(theta*) vs inv. Mass for these pT bins

  12. Cosine(theta*) vs inv mass VS pTD0 cut 0<pT<0.5 0.5<pT<0.1 1<pT<2 2<pT

  13. Counts in cosine(theta*) bins • Evaluate the crossfeed in 2 parts of cosine(theta*) : • [-.6;.6] : used in production • [-1;-.6]U[.6;1] • no dependence of cross feed for central part of cosine(theta*) vs pT D0  crossfeed ~0.45 • Slight dependence (decrease) of cross feed for peripheral values of cosine(theta*) vs pT D0

  14. end

  15. D0 sample used

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