Measurement of V0 production ratios in pp collisions at √s = 0.9 and 7 TeV

The preprint is available here.

More detailed informations: ANA note 2011-026

Eur. Phys. J. C 72 (2012) 2168

arXiv:1107.0882

Abstract

The Λˉ/Λ and Λˉ/K0S production ratios are measured by the LHCb detector from 0.3nb−1 of pp collisions delivered by the LHC at √s=0.9\,TeV and 1.8nb−1 at √s=7\,TeV. Both ratios are presented as a function of transverse momentum, pT, and rapidity, y, in the ranges {0.15<pT<2.50GeV/c} and {2.0<y<4.5}. Results at the two energies are in good agreement as a function of rapidity loss, Δy=ybeam−y, and are consistent with previous measurements. The ratio Λˉ/Λ, measuring the transport of baryon number from the collision into the detector, is smaller in data than predicted in simulation, particularly at high rapidity. The ratio Λˉ/K0S, measuring the baryon-to-meson suppression in strange quark hadronisation, is significantly larger than expected.

Figures

(Note, eps versions are available under attachments).

Caption Figure
The Fisher discriminant FIP in 0.5 million Monte Carlo simulated minimum bias events at √s = 7 TeV for KS0. Fig1a.png
The Fisher discriminant FIP in 0.5 million Monte Carlo simulated minimum bias events at √s = 7 TeV for Λ. Fig1b.png
Invariant mass peaks for Λ in the range 0.25 < pT < 2.50 GeV/c & 2.5 < y < 3.0 at √s = 0.9TeV with field up. Signal yields, N, are found from fits (solid curves) with a double Gaussian peak with common mean, μ, over a linear background (dashed lines). The width, σ, is computed as the quadratic average of the two Gaussian widths weighted by their signal fractions. Fig2a.png
Invariant mass peaks for KS0 in the range 0.65 < pT < 1.00GeV/c & 3.5 < y < 4.0 at √s = 0.9TeV with field up. Signal yields, N, are found from fits (solid curves) with a double Gaussian peak with common mean, μ, over a linear background (dashed lines). The width, σ, is computed as the quadratic average of the two Gaussian widths weighted by their signal fractions. Fig2b.png
Transverse momentum for KS0 in data and Monte Carlo at sqrt(s) = 7 TeV. The difference between data and Monte Carlo is reduced by weighting the simulated candidates. Fig3a.png
Rapidity distributions for KS0 in data and Monte Carlo at sqrt(s) = 7 TeV. The difference between data and Monte Carlo is reduced by weighting the simulated candidates. Fig3b.png
The double ratio (Λ/Λ)Data/(Λ/Λ)MC is shown as a function of the material traversed, in units of radiation length. Flat line fits, shown together with their respective χ2 probabilities, give no evidence of a bias. Fig4a.png
The double ratio (Λ/KS0)Data/(Λ/KS0)MC is shown as a function of the material traversed, in units of radiation length. Flat line fits, shown together with their respective χ2 probabilities, give no evidence of a bias. Fig4b.png
The ratio Λ/Λ from the full analysis procedure at √s = 0.9 TeV, shown as a function of rapidity, compared across intervals of transverse momentum. Vertical lines show the combined statistical and systematic uncertainties and the short horizontal bars (where visible) show the statistical component. Fig5a.png
The ratio Λ/Λ from the full analysis procedure at √s = 7 TeV, shown as a function of rapidity, compared across intervals of transverse momentum. Vertical lines show the combined statistical and systematic uncertainties and the short horizontal bars (where visible) show the statistical component. Fig5b.png
The ratio Λ/KS0 from the full analysis procedure at √s = 0.9 TeV, shown as a function of rapidity, compared across intervals of transverse momentum. Vertical lines show the combined statistical and systematic uncertainties and the short horizontal bars (where visible) show the statistical component. Fig5c.png
The ratio Λ/KS0 from the full analysis procedure at √s = 7 TeV, shown as a function of rapidity, compared across intervals of transverse momentum. Vertical lines show the combined statistical and systematic uncertainties and the short horizontal bars (where visible) show the statistical component. Fig5d.png
The ratio Λ/Λ at √s = 0.9 TeV compared with the predictions of the LHCb MC, Perugia 0 and Perugia NOCR as a function of rapidity. Vertical lines show the combined statistical and systematic uncertainties and the short horizontal bars (where visible) show the statistical component. Fig6a.png
The ratio Λ/Λ at √s = 0.9 TeV compared with the predictions of the LHCb MC, Perugia 0 and Perugia NOCR as a function of transverse momentum. Vertical lines show the combined statistical and systematic uncertainties and the short horizontal bars (where visible) show the statistical component. Fig6b.png
The ratio Λ/KS0 at √s = 0.9 TeV compared with the predictions of the LHCb MC, Perugia 0 and Perugia NOCR as a function of rapidity. Vertical lines show the combined statistical and systematic uncertainties and the short horizontal bars (where visible) show the statistical component. Fig6c.png
The ratio Λ/KS0 at √s = 0.9 TeV compared with the predictions of the LHCb MC, Perugia 0 and Perugia NOCR as a function of transverse momentum. Vertical lines show the combined statistical and systematic uncertainties and the short horizontal bars (where visible) show the statistical component. Fig6d.png
The ratio Λ/Λ at √s = 7 TeV compared with the predictions of the LHCb MC, Perugia 0 and Perugia NOCR as a function of rapidity. Vertical lines show the combined statistical and systematic uncertainties and the short horizontal bars (where visible) show the statistical component. Fig7a.png
The ratio Λ/Λ at √s = 7 TeV compared with the predictions of the LHCb MC, Perugia 0 and Perugia NOCR as a function of transverse momentum. Vertical lines show the combined statistical and systematic uncertainties and the short horizontal bars (where visible) show the statistical component. Fig7b.png
The ratio Λ/KS0 at √s = 7 TeV compared with the predictions of the LHCb MC, Perugia 0 and Perugia NOCR as a function of rapidity. Vertical lines show the combined statistical and systematic uncertainties and the short horizontal bars (where visible) show the statistical component. Fig7c.png
The ratio Λ/KS0 at √s = 7 TeV compared with the predictions of the LHCb MC, Perugia 0 and Perugia NOCR as a function of transverse momentum. Vertical lines show the combined statistical and systematic uncertainties and the short horizontal bars (where visible) show the statistical component. Fig7d.png
The ratio Λ/Λ from LHCb is compared at both √s = 0.9TeV (triangles) and 7TeV (circles) with the published results from STAR[1] (squares) as a function of rapidity loss, ∆y = ybeam − y. Vertical lines show the combined statistical and systematic uncertainties and the short horizontal bars (where visible) show the statistical component. Fig8a.png
The ratio Λ/KS0 from LHCb is compared at both √s = 0.9TeV (triangles) and 7TeV (circles) with the published results from STAR[1] (squares) as a function of rapidity loss, ∆y = ybeam − y. Vertical lines show the combined statistical and systematic uncertainties and the short horizontal bars (where visible) show the statistical component. Fig8b.png

-- TaraShears - 18-Sep-2012

Topic attachments
I Attachment History Action Size Date Who Comment
Unknown file formateps Fig1a.eps r1 manage 13.9 K 2012-09-18 - 15:46 TaraShears  
PNGpng Fig1a.png r1 manage 18.6 K 2012-09-18 - 15:46 TaraShears  
Unknown file formateps Fig1b.eps r1 manage 12.9 K 2012-09-18 - 15:46 TaraShears  
PNGpng Fig1b.png r1 manage 17.8 K 2012-09-18 - 15:46 TaraShears  
Unknown file formateps Fig2a.eps r1 manage 18.1 K 2012-09-18 - 15:45 TaraShears  
PNGpng Fig2a.png r1 manage 29.0 K 2012-09-18 - 15:45 TaraShears  
Unknown file formateps Fig2b.eps r1 manage 18.5 K 2012-09-18 - 15:45 TaraShears  
PNGpng Fig2b.png r1 manage 31.1 K 2012-09-18 - 15:45 TaraShears  
Unknown file formateps Fig3a.eps r1 manage 12.2 K 2012-09-18 - 15:45 TaraShears  
PNGpng Fig3a.png r1 manage 28.8 K 2012-09-18 - 15:45 TaraShears  
Unknown file formateps Fig3b.eps r1 manage 11.9 K 2012-09-18 - 15:45 TaraShears  
PNGpng Fig3b.png r1 manage 26.9 K 2012-09-18 - 15:45 TaraShears  
Unknown file formateps Fig4a.eps r1 manage 8.2 K 2012-09-18 - 15:45 TaraShears  
PNGpng Fig4a.png r1 manage 18.0 K 2012-09-18 - 15:45 TaraShears  
Unknown file formateps Fig4b.eps r1 manage 8.5 K 2012-09-18 - 15:44 TaraShears  
PNGpng Fig4b.png r1 manage 19.0 K 2012-09-18 - 15:44 TaraShears  
Unknown file formateps Fig5a.eps r1 manage 11.3 K 2012-09-18 - 15:44 TaraShears  
PNGpng Fig5a.png r1 manage 32.3 K 2012-09-18 - 15:44 TaraShears  
Unknown file formateps Fig5b.eps r1 manage 12.5 K 2012-09-18 - 15:44 TaraShears  
PNGpng Fig5b.png r1 manage 31.9 K 2012-09-18 - 15:44 TaraShears  
Unknown file formateps Fig5c.eps r1 manage 11.3 K 2012-09-18 - 15:44 TaraShears  
PNGpng Fig5c.png r1 manage 32.2 K 2012-09-18 - 15:44 TaraShears  
Unknown file formateps Fig5d.eps r1 manage 12.3 K 2012-09-18 - 15:44 TaraShears  
PNGpng Fig5d.png r1 manage 32.1 K 2012-09-18 - 15:44 TaraShears  
Unknown file formateps Fig6a.eps r1 manage 9.8 K 2012-09-18 - 15:43 TaraShears  
PNGpng Fig6a.png r1 manage 27.2 K 2012-09-18 - 15:43 TaraShears  
Unknown file formateps Fig6b.eps r1 manage 11.8 K 2012-09-18 - 15:43 TaraShears  
PNGpng Fig6b.png r1 manage 31.4 K 2012-09-18 - 15:43 TaraShears  
Unknown file formateps Fig6c.eps r1 manage 9.1 K 2012-09-18 - 15:43 TaraShears  
PNGpng Fig6c.png r1 manage 24.6 K 2012-09-18 - 15:43 TaraShears  
Unknown file formateps Fig6d.eps r1 manage 10.9 K 2012-09-18 - 15:43 TaraShears  
PNGpng Fig6d.png r1 manage 29.6 K 2012-09-18 - 15:43 TaraShears  
Unknown file formateps Fig7a.eps r1 manage 10.8 K 2012-09-18 - 15:43 TaraShears  
PNGpng Fig7a.png r1 manage 27.8 K 2012-09-18 - 15:43 TaraShears  
Unknown file formateps Fig7b.eps r1 manage 11.6 K 2012-09-18 - 15:42 TaraShears  
PNGpng Fig7b.png r1 manage 31.0 K 2012-09-18 - 15:42 TaraShears  
Unknown file formateps Fig7c.eps r1 manage 10.0 K 2012-09-18 - 15:42 TaraShears  
PNGpng Fig7c.png r1 manage 24.8 K 2012-09-18 - 15:42 TaraShears  
Unknown file formateps Fig7d.eps r1 manage 10.7 K 2012-09-18 - 15:42 TaraShears  
PNGpng Fig7d.png r1 manage 29.2 K 2012-09-18 - 15:42 TaraShears  
Unknown file formateps Fig8a.eps r1 manage 10.8 K 2012-09-18 - 15:42 TaraShears  
PNGpng Fig8a.png r1 manage 33.4 K 2012-09-18 - 15:42 TaraShears  
Unknown file formateps Fig8b.eps r1 manage 11.2 K 2012-09-18 - 15:42 TaraShears  
PNGpng Fig8b.png r1 manage 34.1 K 2012-09-18 - 15:42 TaraShears  
Edit | Attach | Watch | Print version | History: r3 < r2 < r1 | Backlinks | Raw View | WYSIWYG | More topic actions
Topic revision: r3 - 2014-01-17 - KatharinaMueller
 
    • Cern Search Icon Cern Search
    • TWiki Search Icon TWiki Search
    • Google Search Icon Google Search

    LHCb All webs login

This site is powered by the TWiki collaboration platform Powered by PerlCopyright & 2008-2019 by the contributing authors. All material on this collaboration platform is the property of the contributing authors.
Ideas, requests, problems regarding TWiki? Send feedback