Examining the model dependence of the determination of kinetic freeze-out temperature and transverse flow velocity in small collision system

The transverse momentum distributions of the identified particles produced in small collision systems at the Relativistic Heavy Ion Collider(RHIC) and Large Hadron Collider(LHC) have been analyzed by four models. The first two models utilize the blast-wave model with different statistics. The last two models employ certain linear correspondences based on different distributions.The four models describe the experimental data measured by the Pioneering High Energy Nuclear Interaction eXperiment, Solenoidal Tracker at RHIC, and A Large Ion Collider Experiment collaborations equally well. It is found that both the kinetic freeze-out temperature and transverse flow velocity in the central collisions are comparable with those in the peripheral collisions. With the increase of collision energy from that of the RHIC to that of the LHC,the considered quantities typically do not decrease. Comparing with the central collisions, the proton–proton collisions are closer to the peripheral collisions.

3D Fluorescence Characterization of Synthetic Organic Dyes

The identification of dyes is important in research on museum artefacts as well as in forensic applications. UV-visible absorption spectroscopy cannot unambiguously distinguish dyes with similar hues, while mass spectrometry may fail to distinguish isobaric dyes. The detailed patterns produced by 3D fluorescence spectroscopy appear to be virtually unique, even among dyes that are closely related positional isomers. We report these patterns for 65 dyes from the Schweppe Library of Synthetic Organic Dyes as well as measurements suggesting both the capabilities and limitations of this method.

3D Fluorescence Characterization of Synthetic Organic Dyes—Effect of pH

The fingerprint character and high sensitivity of 3D UV-vis fluorescence spectra offer special advantages for identification of dyes in a museum or forensic setting. However, the extraction process is likely to affect the pH of the medium and, in some cases, may alter the dye itself. We report a study of 65 dyes extracted from wool fibers that are part of the Schweppe Collection of Important Synthetic Dyes. The 3D fluorescence spectra of the dye extracts at pH 1 and pH 14 are compared with the same dyes from the Schweppe solution library, run under the same conditions, as well as with the 3D fluorescence spectra of the dyes taken directly from the solution library without pH control. This analysis leads to guidelines for the use of such spectra in identifying unknown dye samples.

Event patterns extracted from top quark-related spectra in proton-proton collisions at 8 TeV

We analyze the transverse momentum （PT） and rapidity （y） spectra of top quark pairs, hadronic top quarks, and top quarks produced in proton-proton （pp） collisions at center-of-mass energy √s=8 TeV. For PT spectra, we use the superposition of the inverse power-law suggested by the QCD （quantum chromodynamics） calculus and the Erlang distribution resulting from a multisource thermal model. For y spectra, we use the two-component Gaussian function resulting from the revised Landau hydrodynamic model. The modelling results are in agreement with the experimental data measured at the detector level, in the fiducial phase-space, and in the full phase-space by the ATLAS Collaboration at the Large Hadron Collider （LHC）. Based on the parameter values extracted from PT and y spectra, the event patterns in three-dimensional velocity （βx-βy-βz）, momentum （px-py-pz）, and rapidity （y1-y2-y） spaces are obtained, and the probability distributions of these components are also obtained. Keywords： top quark-related spectra, event pattern, three-dimensional space