Measurements of multiplicity and transverse momentum fluctuations of charged particles were performed in inelastic p+p interactions at 20, 31, 40, 80, and 158
GeV
/
c
beam momentum. Results for the ...scaled variance of the multiplicity distribution and for three strongly intensive measures of multiplicity and transverse momentum fluctuations
Δ
P
T
,
N
,
Σ
P
T
,
N
and
Φ
p
T
are presented. For the first time the results on fluctuations are fully corrected for experimental biases. The results on multiplicity and transverse momentum fluctuations significantly deviate from expectations for the independent particle production. They also depend on charges of selected hadrons. The string-resonance Monte Carlo models
Epos
and
U
r
qmd
do not describe the data. The scaled variance of multiplicity fluctuations is significantly higher in inelastic p+p interactions than in central Pb+Pb collisions measured by NA49 at the same energy per nucleon. This is in qualitative disagreement with the predictions of the Wounded Nucleon Model. Within the statistical framework the enhanced multiplicity fluctuations in inelastic p+p interactions can be interpreted as due to event-by-event fluctuations of the fireball energy and/or volume.
This paper reports measurements of two-pion femtoscopic correlations in Be+Be collisions at a beam momentum of 150
A
GeV
/
c
(energy available in the center-of-mass system for nucleon pair
s
NN
=
...16.84
GeV) by the NA61/SHINE experiment at the CERN SPS accelerator. The obtained momentum space correlation functions can be well described by a Lévy distributed source model. The transverse mass dependence of the Lévy source parameters is presented, and their possible theoretical interpretations are discussed. The results show that the Lévy exponent
α
is approximately constant as a function of
m
T
, and far from both the Gaussian case of
α
=
2
or the conjectured value at the critical endpoint,
α
=
0.5
. The radius scale parameter
R
shows a slight decrease in
m
T
, which can be explained as a signature of transverse flow. Finally, an approximately constant trend of the intercept parameter
λ
as a function of
m
T
was observed, similar to previous NA44 S + Pb results (obtained with a Gaussian approximation, but unlike RHIC results).
We present a measurement of the momentum spectra of π±, K±, p±, Λ, ¯Λ, and K0S produced in interactions of negatively charged pions with carbon nuclei at beam momenta of 158 and 350 GeV/c. The total ...production cross sections are measured as well. The data were collected with the large-acceptance spectrometer of the fixed target experiment NA61/SHINE at the CERN SPS. The obtained double-differential p−pT spectra provide a unique reference dataset with unprecedented precision and large phase-space coverage to tune models used for the simulation of particle production in extensive air showers in which pions are the most numerous projectiles.
The production of
K
S
0
mesons in inelastic
p+p
collisions at beam momentum 158
GeV
/
c
(
s
NN
=
17.3
GeV
) was measured with the NA61/SHINE spectrometer at the CERN Super Proton Synchrotron. ...Double-differential distributions were obtained in transverse momentum and rapidity. The mean multiplicity of
K
S
0
was determined to be
0.162
±
0.001
(
s
t
a
t
.
)
±
0.011
(
s
y
s
.
)
. The results on
K
S
0
production are compared with model predictions (
EPOS 1.99
, SMASH 2.0, PHSD and UrQMD 3.4 models) as well as with published world data.
The NA61/SHINE experiment at the CERN Super Proton Synchrotron studies the onset of deconfinement in strongly interacting matter through a beam energy scan of particle production in collisions of ...nuclei of varied sizes. This paper presents results on inclusive double-differential spectra, transverse momentum and rapidity distributions and mean multiplicities of
π
±
,
K
±
,
p
and
p
¯
produced in
40
Ar+
45
Sc
collisions at beam momenta of 13
A
, 19
A
, 30
A
, 40
A
, 75
A
and 150
A
Ge
V
/
c
. The analysis uses the 10% most central collisions, where the observed forward energy defines centrality. The energy dependence of the
K
±
/
π
±
ratios as well as of inverse slope parameters of the
K
±
transverse mass distributions are placed in between those found in inelastic
p
+
p
and central Pb + Pb collisions. The results obtained here establish a system-size dependence of hadron production properties that so far cannot be explained either within statistical or dynamical models.
The critical point of dense, strongly interacting matter is searched for at the CERN SPS in
40
Ar +
45
Sc collisions at 150
A
Ge V /
c
. The dependence of second-order scaled factorial moments of ...proton multiplicity distribution on the number of subdivisions of transverse momentum space is measured. The intermittency analysis is performed using both transverse momentum and cumulative transverse momentum. For the first time, statistically independent data sets are used for each subdivision number. The obtained results do not indicate any statistically significant intermittency pattern. An upper limit on the fraction of correlated proton pairs and the power of the correlation function is obtained based on a comparison with the Power-law Model developed for this purpose.
The production cross section of 30.92 GeV/c protons on carbon is measured by the NA61/SHINE spectrometer at the CERN Super Proton Synchrotron by means of beam attenuation in a copy (replica) of the ...90-cm-long target of the T2K neutrino oscillation experiment. The employed method for direct production cross-section estimation minimizes model corrections for elastic and quasielastic interactions. The obtained production cross section is σprod = 227.6 ± 0.8 (stat)+1.9−3.2 (sys) −0.8 (mod) mb. It is in agreement with previous NA61/SHINE results obtained with a thin carbon target, while providing improved precision with a total fractional uncertainty of less than 2%. This direct measurement will reduce the uncertainty of the T2K neutrino flux prediction.
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