Run 2 Diffractive Results

Diffractive Dijet Production at 1.96 TeV

Results are presented from a study of diffractive dijet production in pbar-p collisions at a c.m.s. energy of 1.96 TeV. The data sample consists of events collected by triggering on a high transverse energy jet in coincidence with a recoil antiproton detected in a Roman Pot Spectrometer (RPS). Approximately, the average jet transverse energy in an event is 12 GeV, and the fractional momentum loss of the recoil antiproton, x, and 4-momentun transfer squared, |t|, are in the range 0.03 < x < 0.10 and 0<|t|<0.1 GeV^2, respectively. We measure the ratio of single-diffractive (SD) to non-diffractive (ND) dijet event rates as a function of x-Bjorken and Q^2 in the range 10^-3

Plot Plot Remarks/Comments
Plot2 (.eps), (.gif)

Distribution of antiproton momentum loss fraction, &xi, for RP+J5 and J5 data samples. The regions labeled SD and BG are dominated by SD and background overlap events, respectively.
Plot (.eps), (.gif)

The &xi(CAL) distribution for RP+J5 and J5 data evaluated without MP contributions.
Plot2 (.eps), (.gif)

&xi(CAL) distribution for RP+J5 data, with superimposed &xi(RPS).
Plot5 (.eps), (.gif)

Distribution of antiproton momentum loss fraction measured by the Roman Pot Spectrometer, &xi(RPS) (RP inclusive data).
Plot2 (.eps), (.gif)

Two-dimensional scatter plot of &xi(CAL) versus &xi(RPS) for events with a reconstructed RPS track.
Plot2 (.eps), (.gif)

Distribution of antiproton fractional momentum loss, &xi(CAL) measured from calorimeter information for events in which the &xi(RPS) value measured by the RPS is in the range 0.055<&xi(RPS)<0.060. The line is a gaussian fit.
Plot5 (.eps), (.gif)

Median values of &xi(CAL) obtained from fits to data in different &xi(RPS) bins, plotted versus &xi(RPS). A linear fit describes well the data in the region 0.045<&xi(RPS)<0.090.
Plot (.eps), (.gif)

Mean dijet transverse energy distribution for diffractive (SD), and non-diffractive (ND) events: RP inclusive.
Plot (.eps), (.gif)

Mean dijet transverse energy distribution for diffractive (SD), and non-diffractive (ND) events: RP+J5.
Plot (.eps), (.gif)

Mean dijet transverse energy distribution for diffractive (SD), and non-diffractive (ND) events: RP+J20.
Plot (.eps), (.gif)

Mean dijet transverse energy distribution for diffractive (SD), and non-diffractive (ND) events: RP+J50.
Plot (.eps), (.gif)

Average &eta distribution of the two highest ET jets in the RP+J5 (SD and BG) and J5 samples (ND).
Plot (.eps), (.gif)

Azimuthal angle difference distribution between the two highest $E_T$ jets in the SD and ND samples.
Plot (.eps), (.gif)

Particle multiplicity in the West MP for diffractive (SD) and non-diffractive (ND) events.
Plot (.eps), (.gif)

Ratio of diffractive to non-diffractive dijet event rates as a function of x(Bj) (momentum fraction of parton in the antiproton).
Plot (.eps), (.gif)

Ratio of diffractive to non-diffractive dijet event rates as a function of x_Bj (momentum fraction of parton in the antiproton) for different values of E_T^2=Q^2.
Plot (.eps), (.gif)

|t| distribution (|t|=[0,1]) for positive X shift.
Plot (.eps), (.gif)

The |b_1| slope value versus Y(top) and X(bottom) offsets (normalized to |maximum|).
Plot (.eps), (.gif)

|t| distribution (|t|=[0,1]) for the RP inclusive sample.
Plot (.eps), (.gif)

|t| distribution (|t|=[0,1]) for different samples.
Plot2 (.eps), (.gif)

b1 slope vs Q2 (normalized to RP).
Plot2 (.eps), (.gif)

Azimuthal angle difference between the jets and the outgoing antiproton in the RP+J5 sample. The jet angle is that of the leading jet (red squares) or the average of the angles of the two leading jets (black circles).

Michele Gallinaro
Last modified: Fri Jun 9 12:03:19 EDT 2006