Measurement of Beauty & Charm Photoproduction at H1 using Inclusive Lifetime Tagging

Size: px

Start display at page:

Download "Measurement of Beauty & Charm Photoproduction at H1 using Inclusive Lifetime Tagging"

Tyler Franklin
7 years ago
Views:

1 Measurement of Beauty & Charm Photoroduction at H using Inclusive Lifetime Tagging Lars Finke Aril, 9th 005 Heavy Flavors Working Grou

2 Photoroduction of Beauty & Charm at HERA e g c, b g Relevant scales: m c,b :.5 (4.75) GeV Theory models: LO O (α s ) + Parton shower c,b T : Event selection:, t >, 8 GeV DGLAP evolution, incl. flavor excitation PYTHIA CCFM evolution CASCADE NLO O (α s ) calculations Heavy quarks: Multiscale roblem in QCD. FMNR (fixed order massive) Lars Finke, Hamburg University DIS 005 9/04/005 µ

3 Motivation Heavy quark roduction in e collisions at HERA: Sensitivity to roton and hoton structure. Parton dynamics of the hard scattering. Hard scale rovided by the heavy quark masses (m c, m b ). Factorisation and erturbative QCD (massive/massless). Aims of this analysis: First inclusive measurement of beauty & charm Dis at high t in hotoroduction. Inclusive lifetime tag Large statistics Large t ( t > m b ). Lars Finke, Hamburg University DIS 005 9/04/005 µ

4 Heavy Flavor Signal Extraction Use of recise tracking information available from H vertex detector Signed Imact Parameter: α < π/ DCA = + DCA α > π/ DCA α Jet DCA DCA = DCA. Vertex Jet α Tracks 5 4 B C UDS Sum. Vertex Track Track MC used for simulation of b, c and uds DCA [cm] Marked asymmetry for heavy quarks. Anti strangeness cut: DCA < mm (remove e.g. K 0 S ) Tracks B C UDS Sum Significance= DCA i σ(dca i ) Significance Lars Finke, Hamburg University DIS 005 9/04/005 µ

5 Lifetime Observables I Using significances of the two highest significance tracks, S and S y cm samle event Events 5 4 B C UDS Sum S S rim. vertex S Highest significance track for track events. x cm Events S B C UDS Sum S Significance of the nd highest significance track for > track events S Lars Finke, Hamburg University DIS 005 9/04/005 µ 4

6 Negative Subtraction Subtract negative bins in S & S from the ositive Entries Entries 400 B B C UDS Fit C UDS Fit S S Reduces sensitivity to resolution descrition of light quarks. Subtracted sectrum dominated by charm. Increasing beauty fraction at higher significances. Contribution from light quarks negligible. Fit scale factors for beauty, charm and uds from negative subtracted sectra (+ total number of events). S Lars Finke, Hamburg University DIS 005 9/04/005 µ 5

7 Integrated Cross Section Kinematic range: Q < GeV, 0.5 < y < 0.8, t > (8) GeV, 0.88 < η <. Beauty: σ(e eb bx ejjx) = 49 ± 8 ± b Charm: σ(e ec cx ejjx) = 694 ± 69 ± 97 b Dominating systematic error. Main contributions come from the track resolutions and model uncertainties. Fractions: Beauty (Charm) fraction tyically 7% ( 5%). Lars Finke, Hamburg University DIS 005 9/04/005 µ 6

8 Lifetime Observables II Alternative lifetime tag Jet Probability*: Use all selected tracks within the two leading s. Entries 5 4 B C Construct a robability P MIP (from the significances) that the s are comatible with the rimary vertex. UDS Fit Low (i.e. large negative logarithm) robabilities indicate secondary vertex. Fit fractions of beauty, charm and light quarks. (*follows ALEPH aer Phys. Lett. B (99) 55) log (P MIP ) Resulting cross sections are found to agree with the results obtained with S and S. Lars Finke, Hamburg University DIS 005 9/04/005 µ 7

9 Beauty & Charm in Photoroduction dσ/d t (e > ecc(bb)x > ejjx) H 99/00 e + data: Q 0, 0.5 < y < 0.8 t > (8) GeV, 0.88 < η <. [b/gev] dσ/d t BEAUTY dσ/d t (e >ebbx >ejjx) Pythia Pythia res. Cascade NLO QCD had Q < GeV, 0.5 < y < 0.8 t > (8) GeV 0.88 < η Jet <. [b/gev] dσ/d t CHARM dσ/d t (e >eccx >ejjx) Pythia Pythia res. Cascade NLO QCD had Q < GeV, 0.5 < y < 0.8 t > (8) GeV Jet 0.88 < η < t [GeV] LO + PS QCD Models: Good descrition of shae. NLO QCD (FMNR): Slightly higher (at low t ) t LO + PS QCD Models: Good descrition of shae and norm. NLO QCD (FMNR): Fits within uncertainties. [GeV] Lars Finke, Hamburg University DIS 005 9/04/005 µ 8

10 Beauty & Charm in Photoroduction dσ/dη (e > ecc(bb)x > ejjx) H 99/00 e + data: Q 0, 0.5 < y < 0.8 t > (8) GeV, 0.88 < η <. [b] dσ/dη BEAUTY Pythia Pythia res. Cascade NLO QCD had dσ/dη (e >ebbx >ejjx) [b] dσ/dη CHARM Pythia Pythia res. Cascade NLO QCD had dσ/dη (e >eccx >ejjx) Q < GeV, 0.5 < y < 0.8 t > (8) GeV Jet 0.88 < η <. Q < GeV, 0.5 < y < t > (8) GeV Jet 0.88 < η < η η LO + PS QCD Models & NLO QCD (FMNR): Main differences in forward region. LO + PS QCD Models: Good descrition of shae and norm. NLO QCD (FMNR): Fits within uncertainties. Lars Finke, Hamburg University DIS 005 9/04/005 µ 9

11 Beauty Contributions from Resolved Photons dσ/dx obs (e > ebbx > ejjx) H 99/00 e + data: Q 0, 0.5 < y < 0.8 t > (8) GeV, 0.88 < η <. [b] obs dσ/dx 4 BEAUTY Pythia Pythia res. Cascade NLO QCD NLO QCD had obs dσ/dx (e >ebbx >ejjx) resolved like excitation g x obs = P, (E P z ) P hadrons (E P z) obs x LO + PS QCD Models: PYTHIA shae okay but too low in normalisation. CASCADE too hard. NLO QCD (FMNR): Lower than data at low x obs. Significant resolved like comonent (x obs < 0.85). Lars Finke, Hamburg University DIS 005 9/04/005 µ

12 Charm Contributions from Resolved Photons dσ/dx obs (e > eccx > ejjx) H 99/00 e + data: Q 0, 0.5 < y < 0.8 t > (8) GeV, 0.88 < η <. [b] obs dσ/dx 4 CHARM Pythia Pythia res. Cascade NLO QCD NLO QCD had Q < GeV, 0.5 < y < 0.8 t > (8) GeV Jet 0.88 < η <. obs dσ/dx (e >eccx >ejjx) resolved like x obs = excitation P, (E P z ) P hadrons (E P z) g obs x Significant resolved like comonent (x obs < 0.85). LO + PS QCD Models: PYTHIA with large excitation comonent okay, but too low for high x obs. CASCADE too hard. NLO QCD (FMNR): Good agreement between Data and NLO QCD within (large) uncertainties! Lars Finke, Hamburg University DIS 005 9/04/005 µ

13 Conclusion Measurement of beauty & charm di cross sections in hotoroduction has been resented. H Silicon Vertex Detector 99/00 data. High t : Beauty (Charm) fraction 7% ( 5%) of total samle with x obs > In agreement with quark charge counting. Charm: Data in general agreement with NLO QCD rediction (within uncertainties). Resolved contributions somewhat underestimated by the NLO calculation. Beauty: Data somewhat higher than NLO QCD, PYTHIA and CASCADE. Shae well described. Main differences seen at low x obs and at lower t. Lars Finke, Hamburg University DIS 005 9/04/005 µ

Backu NLO Calculations FMNR: fixed order massive calculation: BGF and HO Calculations done in MS scheme using CT EQ5M, GRV -HO and m C =.5 GeV (m B = 4.75 GeV).

14 Backu NLO Calculations FMNR: fixed order massive calculation: BGF and HO Calculations done in MS scheme using CT EQ5M, GRV -HO and m C =.5 GeV (m B = 4.75 GeV). µ r = m t = m q + t,q q µ beauty f = m t ; µ charm f = m t t weighted k t clustering algorithm used. Perturbative uncertainties estimated by variation of the scales µ r and µ f (/ ). Parameter uncertainties estimated by variation of the quark masses and the df (added quadratically). Parton to hadron level corrections done using PYTHIA. Total uncertainties: 0% for both, beauty and charm. Lars Finke, Hamburg University DIS 005 9/04/005 µ

Measurement of Neutralino Mass Differences with CMS in Dilepton Final States at the Benchmark Point LM9

Measurement of Neutralino Mass Differences with CMS in Dilepton Final States at the Benchmark Point LM9, Katja Klein, Lutz Feld, Niklas Mohr 1. Physikalisches Institut B RWTH Aachen Introduction Fast discovery