We report results on event-by-event fluctuations of transverse momentum, Phi(p(t)), in pi(+)p and K(+)p collisions at 250 GeV/c. For the first time, their dependence on rapidity region, transverse ...momentum acceptance, multiplicity, mean transverse momentum per event, and on the correlation between transverse momentum and multiplicity are systematically presented. The results are compared with those from the PYTHIA Monte Carlo generator. The fluctuations under the same acceptance cuts as used in current heavy-ion experiments are also presented.
The transverse energy carried by charged hadrons and by \({\pi}^-\) mesons is studied in interactions of \({\pi}^+\) and K\(^+\) mesons with protons and nuclei at 250 GeV/c. The data obtained on ...transverse energy flow at mid-rapidity can be described by the FRITIOF7.0 model with tuned parameters.
Taking into account the anisotropy of phase space in multiparticle production, a self-affine analysis of factorial moments was carried out on the NA22 data for
π
+p and K
+p collisions at 250 GeV/
c. ...Within the transverse plane, the Hurst exponents measuring the anisotropy are consitent with unit value (i.e. no anisotropy). They are, however, only half that value when the longitudinal direction is compared to the transverse ones. Fractality, indeed, turns out to be self-affine rather than self-similar in multiparticle production. In three-dimensional phase space, power-law scaling is observed to be better realized in self-affine than in self-similar analysis.
The invariant spectra of
π
− mesons produced in (
π
+/K
+)p interactions at 250 GeV/
c are analysed in the framework of the hydrodynamical model of three-dimensionally expanding cylindrically ...symmetric finite systems. A satisfactory description of experimental data is achieved. The data favour the pattern according to which the hadron matter undergoes predominantly longitudinal expansion and non-relativistic transverse expansion with mean transverse velocity 〈
u
t〉=0.20±0.07, and is characterized by a large temperature inhomogeneity in the transverse direction: the extracted freeze-out temperature at the center of the tube and at the transverse rms radius are 140±3 MeV and 82±7 MeV, respectively. The width of the (longitudinal) space-time rapidity distribution of the pion source is found to be
Δη=1.36±0.02. Combining this estimate with results of the Bose-Einstein correlation analysis in the same experiment, one extracts a mean freeze-out time of the source of 〈
τ
f〉=1.4±0.1 fm/
c and its transverse geometrical rms radius,
R
G(rms)=1.2±0.2 fm.
Spike production is studied in pp and π
+p/K
+p collisions in the beam-momentum range of 205–360 GeV/c. The pseudorapidity distribution of spike centers exhibits two narrow peaks in pp interactions, ...while having one wide bump in πp and Kp interactions. The position of the peaks is consistent with the expectation from a model of coherent gluon radiation at finite length. The interference between the quark color amplitudes obtained within this model causes two off-center peaks in pp data, but only one central peak in πp and Kp data.
Two suggested moments of rapidity gaps are studied on π+p and K+p collisions at 250 GeV/c. The experimental results are compared with those obtained from Pythia simulation. The efficiency of the ...method is discussed.
We have measured the factorial moments up to fifth order, as well as the second-order normalized differential factorial moments, both as a function of the difference of transverse momentum (
Δp
T) in
...π
+p and K
+p collisions at 250 GeV/
c. The second-order differential factorial moments for like-charged pairs reveal a strong increase with decreasing
Δp
T. In a small central rapidity window, this increase is described by a simple power law. If interpreted as originating from Bose-Einstein correlations, such a behavior indicates a power-law structure of the transverse spatial distribution of the particle source.
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