Dijet mass analysis - preliminary results from March 2003

We present the inclusive dijet mass cross section measurement within |eta|<0.5. All jets are reconstructed using the cone algorithm with a radius of 0.7. A good agreement between NLO QCD and data is found.

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QCD NLO prediction (JETRAD) for central inclusive dijet mass cross section in proton anti-proton collisions at RunI and RunII energies. The CTEQ6M parton distribution function was used in the calculation. The plot demonstrates that the cross section in the last RunI bin (starting at 800 GeV) should be more than two times larger at RunII energy than at RunI.

eps, gif
Distribution of the difference of the azimuthal angle for the two leading jets from the dijet sample for events in trigger JT_25TT with a dijet mass above 150 GeV (JT_25TT trigger turn-on point). The only correction that was applied is jet energy scale (it goes into the plot indirectly through cut on dijet mass).

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Distribution of the difference between the azimuthal angles of the two leading jets from the dijet sample for events passing the JT_45TT trigger with a dijet mass above 180 GeV. The only correction that was aplied is the jet energy scale correction (which enters the plot indirectly via the cut on dijet mass).

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Distribution of the difference between the azimuthal angles of the two leading jets from the dijet sample for events passing the JT_65TT trigger with a dijet mass above 300 GeV. The only correction that was aplied is the jet energy scale correction (which enters the plot indirectly via the cut on dijet mass).

eps, gif
Distribution of the difference between the azimuthal angles of the two leading jets from the dijet sample for events passing the JT_95TT trigger with a dijet mass above 390 GeV. The only correction that was aplied is the jet energy scale correction (which enters the plot indirectly via the cut on dijet mass).

eps, gif
Distribution of the azimuthal angles of the two leading jets from the dijet sample for events passing the JT_95TT trigger with a dijet mass above 390 GeV. The only correction that was aplied is the jet energy scale correction (which enters the plot indirectly via the cut on dijet mass). The chi2 of the constant line fit is chi2/NDF = 28/31.

eps, gif
Distribution of the average rapidity of the two leading jets from the dijet sample for events passing the JT_95TT trigger with a dijet mass above 390 GeV. The only correction that was aplied is the jet energy scale correction (which enters the plot indirectly via the cut on dijet mass). The chi2 of the constant line fit is chi2/NDF = 28/31.

eps, gif
Distribution of the transverse momenta of the two leading jets from the dijet sample for events passing the JT_95TT trigger with a dijet mass above 390 GeV. The only correction that was aplied is the jet energy scale correction (which enters the plot indirectly via the cut on dijet mass). The chi2 of the constant line fit is chi2/NDF = 28/31.

eps, gif
Jet pT resolution for R=0.7 cone jets in the central calorimeter region (|eta|<0.5) measured from the dijet transverse momentum imbalance. The error bars correspond to the fit errors on the asymmetry variable distribution. Solid line is the result of the standard fit on data (sqrt(N^2/pT^2 + S^2/PT + C^2)), the fit error is given by the yellow band.

eps, gif
Dijet mass resolution for R=0.7 cone jets in the central calorimeter region (|eta|<0.5) obtained from the dijet transverse momentum imbalance. The data points correspond to the MC result on dijet mass resolution using the Pythia MC with a particular jet PT cut. The error bars correspond to the statistical error. The solid line is the result of the standard fit on data (sqrt(N^2/pT^2 + S^2/PT + C^2)), the fit error is given by the yellow band.

eps, gif
Raw dijet mass cross section for various triggers. JES, vertex efficiency, and jet ID cut efficiencies are applied on data. The only correction that was not applied is the unsmearing one. 'L1 5 GeV Trigger' is the CJT5 trigger (requires at least one L1 tower above 5 GeV). All other triggers are regular jet triggers with L1, L2 L3 filters. The numbers give the jet pT cut at L3.

eps, gif
Calorimeter 2D lego plot for the highest dijet mass event(Run 163526, event 12649416). The dijet mass is (after JES correction) 838 GeV, the transverse momenta of the leading jets are 432GeV and 396GeV (after JES).

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3D event display for the highest dijet mass event. (Run 163526, event 12649416). The dijet mass is (after JES correction) 838 GeV, the trasnverse momenta of the leading jets are 432GeV and 396GeV (after JES).

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Unsmearing correction. The solid line shows the correction for the used ansatz function, the dashed line corresponds to a different form of ansatz function.

eps, gif
Dijet mass cross section for the cone R=0.7 jet algorithm in the central region, |eta|<0.5, of the calorimeter. The error bars show the total error, and the small perpendicular lines show statistical error. There is an additional 10% error on luminosity which is not plotted. The error on x-position is around the bin center value in that bin (computed from the ansatz function fit). The red dashed line represents the NLO QCD prediction calculated using JETRAD with the CTEQ6M parton distribution functions and Rsep=1.3. Factorization and renormalization scale were set to 50% of the maximum jet E_T. The highest mass bin contains only 3 events.

eps, gif
(Data - Theory) / Theory plot for the central dijet mass cross section. Theory is the NLO QCD prediction of JETRAD using the CTEQ6M parton distribution function and Rsep=1.3. Factorization and renormalization scale were set to 50% of the maximum jet E_T. The errors are statistical, the red upper and lower lines show the systematic error (mainly comming from JES). There is an additional 10% error on luminosity which is not plotted.

eps, gif
(Data - Theory) / Theory plot for the central dijet mass cross section. Theory is the NLO QCD prediction of JETRAD using the MRST2001 parton distribution function and Rsep=1.3. Factorization and renormalization scale were set to 50% of the maximum jet E_T. The errors are statistical, the red upper and lower lines show the systematic error (mainly comming from JES). There is an additional 10% error on luminosity which is not plotted.

Last update 2^nd Apr 2003.

eps, gif	QCD NLO prediction (JETRAD) for central inclusive dijet mass cross section in proton anti-proton collisions at RunI and RunII energies. The CTEQ6M parton distribution function was used in the calculation. The plot demonstrates that the cross section in the last RunI bin (starting at 800 GeV) should be more than two times larger at RunII energy than at RunI.
eps, gif	Distribution of the difference of the azimuthal angle for the two leading jets from the dijet sample for events in trigger JT_25TT with a dijet mass above 150 GeV (JT_25TT trigger turn-on point). The only correction that was applied is jet energy scale (it goes into the plot indirectly through cut on dijet mass).
eps, gif	Distribution of the difference between the azimuthal angles of the two leading jets from the dijet sample for events passing the JT_45TT trigger with a dijet mass above 180 GeV. The only correction that was aplied is the jet energy scale correction (which enters the plot indirectly via the cut on dijet mass).
eps, gif	Distribution of the difference between the azimuthal angles of the two leading jets from the dijet sample for events passing the JT_65TT trigger with a dijet mass above 300 GeV. The only correction that was aplied is the jet energy scale correction (which enters the plot indirectly via the cut on dijet mass).
eps, gif	Distribution of the difference between the azimuthal angles of the two leading jets from the dijet sample for events passing the JT_95TT trigger with a dijet mass above 390 GeV. The only correction that was aplied is the jet energy scale correction (which enters the plot indirectly via the cut on dijet mass).
eps, gif	Distribution of the azimuthal angles of the two leading jets from the dijet sample for events passing the JT_95TT trigger with a dijet mass above 390 GeV. The only correction that was aplied is the jet energy scale correction (which enters the plot indirectly via the cut on dijet mass). The chi2 of the constant line fit is chi2/NDF = 28/31.
eps, gif	Distribution of the average rapidity of the two leading jets from the dijet sample for events passing the JT_95TT trigger with a dijet mass above 390 GeV. The only correction that was aplied is the jet energy scale correction (which enters the plot indirectly via the cut on dijet mass). The chi2 of the constant line fit is chi2/NDF = 28/31.
eps, gif	Distribution of the transverse momenta of the two leading jets from the dijet sample for events passing the JT_95TT trigger with a dijet mass above 390 GeV. The only correction that was aplied is the jet energy scale correction (which enters the plot indirectly via the cut on dijet mass). The chi2 of the constant line fit is chi2/NDF = 28/31.
eps, gif	Jet pT resolution for R=0.7 cone jets in the central calorimeter region (\|eta\|<0.5) measured from the dijet transverse momentum imbalance. The error bars correspond to the fit errors on the asymmetry variable distribution. Solid line is the result of the standard fit on data (sqrt(N^2/pT^2 + S^2/PT + C^2)), the fit error is given by the yellow band.
eps, gif	Dijet mass resolution for R=0.7 cone jets in the central calorimeter region (\|eta\|<0.5) obtained from the dijet transverse momentum imbalance. The data points correspond to the MC result on dijet mass resolution using the Pythia MC with a particular jet PT cut. The error bars correspond to the statistical error. The solid line is the result of the standard fit on data (sqrt(N^2/pT^2 + S^2/PT + C^2)), the fit error is given by the yellow band.
eps, gif	Raw dijet mass cross section for various triggers. JES, vertex efficiency, and jet ID cut efficiencies are applied on data. The only correction that was not applied is the unsmearing one. 'L1 5 GeV Trigger' is the CJT5 trigger (requires at least one L1 tower above 5 GeV). All other triggers are regular jet triggers with L1, L2 L3 filters. The numbers give the jet pT cut at L3.
eps, gif	Calorimeter 2D lego plot for the highest dijet mass event(Run 163526, event 12649416). The dijet mass is (after JES correction) 838 GeV, the transverse momenta of the leading jets are 432GeV and 396GeV (after JES).
eps, gif	3D event display for the highest dijet mass event. (Run 163526, event 12649416). The dijet mass is (after JES correction) 838 GeV, the trasnverse momenta of the leading jets are 432GeV and 396GeV (after JES).
eps, gif	Unsmearing correction. The solid line shows the correction for the used ansatz function, the dashed line corresponds to a different form of ansatz function.
eps, gif	Dijet mass cross section for the cone R=0.7 jet algorithm in the central region, \|eta\|<0.5, of the calorimeter. The error bars show the total error, and the small perpendicular lines show statistical error. There is an additional 10% error on luminosity which is not plotted. The error on x-position is around the bin center value in that bin (computed from the ansatz function fit). The red dashed line represents the NLO QCD prediction calculated using JETRAD with the CTEQ6M parton distribution functions and Rsep=1.3. Factorization and renormalization scale were set to 50% of the maximum jet E_T. The highest mass bin contains only 3 events.
eps, gif	(Data - Theory) / Theory plot for the central dijet mass cross section. Theory is the NLO QCD prediction of JETRAD using the CTEQ6M parton distribution function and Rsep=1.3. Factorization and renormalization scale were set to 50% of the maximum jet E_T. The errors are statistical, the red upper and lower lines show the systematic error (mainly comming from JES). There is an additional 10% error on luminosity which is not plotted.
eps, gif	(Data - Theory) / Theory plot for the central dijet mass cross section. Theory is the NLO QCD prediction of JETRAD using the MRST2001 parton distribution function and Rsep=1.3. Factorization and renormalization scale were set to 50% of the maximum jet E_T. The errors are statistical, the red upper and lower lines show the systematic error (mainly comming from JES). There is an additional 10% error on luminosity which is not plotted.