Preliminary results from the correlation femtoscopy of identical kaons in the SELEX experiment (Fermilab E781) are presented. Kaons are selected in inclusive reactions of Σ
−
C(Cu) interactions at an ...initial energy of 610 GeV. Kaon pairs are studied in all possible charged states: K
s
0
K
s
0
, K
s
0
K
+
, K
s
0
K
−
, K
+
K
+
, K
+
K
−
and K
−
K
−
. The source sizes of the hadronization region of neutral and charged kaon pairs are measured.
Correlation femtoscopy provides information about the space-time structure and evolution of the fireball created in ultra-relativistic nucleus-nucleus collisions. The dependence of the femtoscopic ...radii on transverse pair momentum and charged particle multiplicity of an event reflects the mechanism of collective behavior. In this work, the femtoscopic radii of identical charged pions were calculated in the UrQMD model for Au+Au and p+Au collisions at sNN=200GeV and compared to each other at the same multiplicities. The physics implications of this comparison will be discussed.
We report measurements of the photon beam asymmetry for the reactions γp → pπ0 and γp → pη from the GLUEX experiment using a 9 GeV linearly polarized, tagged photon beam incident on a liquid hydrogen ...target in Jefferson Lab’s Hall D. The asymmetries, measured as a function of the proton momentum transfer, possess greater precision than previous π0 measurements and are the first η measurements in this energy regime. The results are compared with theoretical predictions based on t-channel, quasiparticle exchange and constrain the axial-vector component of the neutral meson production mechanism in these models.
The main results of the data processing and physical analysis of the SELEX experiment and the preliminary data on correlations of antiprotons with small relative momentum are presented. Correlation ...femtoscopy is a powerful tool for studying the spatial-temporal characteristics of the emission region of identical particles. The correlation functions obtained in the SELEX and STAR experiments are compared.
We present a study of collective effects and dynamics of quark-hadron phase transitions by means of the femtoscopic correlations of hadrons at the NICA energies. A set of simulations of heavy-ion ...collisions (AuAu, BiBi) at the energies to be available with the NICA collider and experiments to be operated there (in particular, the MPD experiment), has been performed using two Monte Carlo generators. A femtoscopic analysis for charged pions and kaons have shown a sensitivity of the observables to the equation of state (EoS) for both event generators. Also, a study of the influence of detector effects like track-merging and track-splitting in the TPC, the main tracker device of the MPD experiment, on femtoscopic measurements is presented in this work.
The study of the scaled factorial moments of the multiplicity distribution in rapidity intervals as function of the rapidity interval size is presented for Au + Au interactions at √
s
NN
= 7.7 and ...11.5 GeV using the HYDJET++, UrQMD and vHLLE+UrQMD generators. This measurement is sensitive to the size and power of the multiparticle correlations. The sensitivity of the measurement to the initial conditions and properties of nuclear matter equation of state is discussed.
The correlation femtoscopy allows one to measure the space-time characteristics of particle production processes due to the effects of quantum statistics (QS) and final state interactions (FSI). ...Femtoscopy at lower energies was intensively studied at AGS, SPS and in the Beam Energy Scan (BES) program at RHIC. In the work we discuss possibilities to observe a difference from the first-order phase transition expected, according some theoretical predictions, at low energies and the crossover one, to be occurred at high energies, with the femtoscopy observables using the hybrid model vHLLE + UrQMD. The possibilities to use kaon femtoscopy complementary to the usually used pion one are discussed.
We report the measurement of the one-dimensional charged kaon correlation functions using 600GeV/cΣ−, π− and 540GeV/cp beams from the SELEX (E781) experiment at the Fermilab Tevatron. K±K± ...correlation functions are studied for three transverse pair momentum, kT, ranges and parameterized by a Gaussian form. The emission source radii, R, and the correlation strength, λ, are extracted. The analysis shows a decrease of the source radii with increasing kaon transverse pair momentum for all beam types.
The polarization of Λ and Λover ¯ hyperons along the beam direction has been measured relative to the second and third harmonic event planes in isobar Ru+Ru and Zr+Zr collisions at sqrts_{NN}=200 ...GeV. This is the first experimental evidence of the hyperon polarization by the triangular flow originating from the initial density fluctuations. The amplitudes of the sine modulation for the second and third harmonic results are comparable in magnitude, increase from central to peripheral collisions, and show a mild p_{T} dependence. The azimuthal angle dependence of the polarization follows the vorticity pattern expected due to elliptic and triangular anisotropic flow, and qualitatively disagrees with most hydrodynamic model calculations based on thermal vorticity and shear induced contributions. The model results based on one of existing implementations of the shear contribution lead to a correct azimuthal angle dependence, but predict centrality and p_{T} dependence that still disagree with experimental measurements. Thus, our results provide stringent constraints on the thermal vorticity and shear-induced contributions to hyperon polarization. Comparison to previous measurements at RHIC and the LHC for the second-order harmonic results shows little dependence on the collision system size and collision energy.
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