Measurements of inclusive anti-Lambda0 production with large x(F) at the SpS Collider

The UA8 collaboration Brandt, A. ; Erhan, S. ; Kuzucu, A. ; et al.
Nucl.Phys. B519 (1998) 3-18, 1998.
Inspire Record 452309 DOI 10.17182/hepdata.32680

We report results of inclusive measurements of anti-Lambda, produced in the forward direction at the SPS with sqrt(s) = 630 GeV, using the UA8 small angle Roman Pot spectrometers. These measurements cover the range in Feynman-x_f and transverse momentum, 0.6 < x_f < 1.0 and 0.4 < p_t < 0.7 GeV, respectively. Within a systematic uncertainty of +-20% on the absolute cross section measurements, the results are indistinguishable from those made by some of us in two earlier experiments at the CERN Intersecting Storage Rings, with energies, sqrt(s) = 53 and 62 GeV. In the x_f-range, 0.6-0.9, the absolute cross sections are lower by a factor of 2 to 3 than the predictions of the Lund model as embodied in the PYTHIA 5.6 and JETSET 7.3 Monte Carlo programs, indicating inadequacies in knowledge of the baryon fragmentation function. For the largest x_f-range, 0.9-1.0, the measurements agree with the Monte Carlo predictions. We have measured the average anti-Lambda polarization for our events and find (6 +- 12%), consistent with previous measurements at the ISR in the present region of x_f - p_t.

3 data tables

Invariant cross section for inclusive LAMBDABAR production, multiplied by a factor 2, from the UP spectrometer.

Invariant cross section for inclusive LAMBDABAR production, multiplied by a factor 2, from the DOWN spectrometer.

The measured LAMBDABAR polarization.


A Study of inclusive double pomeron exchange in $p \bar{p} \to p X \bar{p}$ at $\sqrt{s}$ = 630-GeV

The UA8 collaboration Brandt, A. ; Erhan, S. ; Kuzucu, A. ; et al.
Eur.Phys.J. C25 (2002) 361-377, 2002.
Inspire Record 586770 DOI 10.17182/hepdata.43241
2 data tables

The corrected differential cross section as a function of the mass of the central system X for the 'AND' and 'OR' data sets.

Mass dependence of the Pomeron-Pomeron total cross section derived from the'AND' and 'OR' data sets.


Measurements of single diffraction at $\sqrt{s}$ = 630-GeV: Evidence for a nonlinear $alpha_t$ of the Pomeron

The UA8 collaboration Brandt, A. ; Erhan, S. ; Kuzucu, A. ; et al.
Nucl.Phys. B514 (1998) 3-44, 1998.
Inspire Record 449347 DOI 10.17182/hepdata.32682

We report measurements of the inclusive differential cross section for the single-diffractive reactions: p + pbar --> p + X and p + pbar --> X + pbar at sqrt(s) = 630 GeV, in the momentum transfer range, 0.8 < -t < 2.0 GeV^2 and final state Feynman-x > 0.90. Based on the assumption of factorization, several new features of the Pomeron Flux Factor are determined from simultaneous fits to our UA8 data and lower energy data from the CHLM collaboration at the CERN-Intersecting Storage Rings. Prominent among these is that the effective Pomeron Regge trajectory requires a term quadratic in t, with coefficient, a'' = 0.079 +- 0.012 GeV^{-4}. We also show that the data require a Pomeron-proton cross section that first decreases with increasing diffractive mass (corresponding to the PPR term in the triple-Regge expansion) and then increases at larger mass (the PPP term), similar to real particle total cross sections. We measure the product, (K x sigma0) = 0.72 +- 0.10 mb/GeV^2, where K is the normalization constant of the Pomeron Flux Factor in the proton and sigma0 is the scale constant in the Pomeron-proton total cross section. Finally, we report the occurence of ``beam jets'' in the Pomeron direction in the rest frame of the diffractive system.

5 data tables

Single diffractive cross sections.

Single diffractive sdig/dt for X > 0.95.

The average energy flow event in the C.M. frame of the system X for different values of S prime (the invariant Squark mass of the X system).

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