Search Results (8)

Cumulants up to the sixth-order of the net-particle multiplicity distributions were measured at RHIC for the Beam Energy Scan and fixed-target program, from which we obtained some interesting hints on the phase structure of the QCD matter. In this article, we present recent experimental results on (net-)proton cumulants and discuss current interpretations on the QCD critical point and the nature of the phase transition. We will also report recent results for measurements of the bayron-strangeness correlations, which were measured with the newly developed analysis technique to remove the effect from the combinatorial backgrounds for hyperon reconstruction. Full article

Fast and efficient algorithms optimized for high performance computers are crucial for the real-time analysis of data in heavy-ion physics experiments. Furthermore, the application of neural networks and other machine learning techniques has become more popular in physics experiments over the last years. For that reason, a fast neural network package called ANN4FLES is developed in C++, which will be optimized to be used on a high performance computer farm for the future Compressed Baryonic Matter (CBM) experiment at the Facility for Antiproton and Ion Research (FAIR, Darmstadt, Germany). This paper describes the first application of ANN4FLES used in the reconstruction chain of the CBM experiment to replace the existing particle competition between $K_s$-mesons and $\mathrm{\Lambda }$-hyperons in the KF Particle Finder by a neural network based approach. The raw classification performance of the neural network reaches over 98% on the testing set. Furthermore, it is shown that the background noise was reduced by the neural network-based competition and therefore improved the quality of the physics analysis. Full article

The MicroBooNE detector is a liquid argon time projection chamber (LArTPC) with an 85 ton active mass that receives flux from the Booster Neutrino and the Nutrinos from the Main Injector (NuMI) beams, providing excellent spatial resolution of the reconstructed final-state particles. Since 2015, MicroBooNE has accumulated many neutrino and anti-neutrino scattering events with argon nuclei enabling searches for rare interaction channels. The Cabibbo-suppressed production of hyperons in anti-neutrino–nucleus interactions provides sensitivity to a range of effects, including second-class currents, SU(3) symmetry violations and reinteractions between the hyperon and the nuclear remnant. This channel exclusively involves anti-neutrinos, offering an unambiguous constraint on wrong-sign contamination. The effects of nucleon structure and final state interactions are distinct from those affecting the quasielastic channel and modify the $\Lambda$ and $\Sigma$ production cross sections in different ways, providing new information that could help to break their degeneracy. Few measurements of this channel have been made, primarily in older experiments such as Gargamelle. We present the sensitivity of the MicroBooNE experiment to the cross section for direct (Cabibbo-suppressed) $\Lambda$ production in muon anti-neutrino interactions, using anti-neutrinos from the off-axis NuMI beam. Full article

Study of the strangeness production in heavy-ion collisions is one of the most important parts of the physics program of the BM@N and MPD experiments at the NICA accelerator complex. With collision energies $\sqrt{s_{NN}}$ of 2.3–3.3 GeV in the fixed target mode at BM@N and 4–11 GeV in the collider mode at MPD, the experiments will cover the region of the maximum net baryon density and provide high-statistics complementary data on different physics probes. In this paper, some results of Monte Carlo studies of hyperon production with the BM@N and MPD experiments are presented, demonstrating their performance for investigation of the objects with strangeness. Full article

We present the current status of the performance studies of $\mathsf{\Lambda }$ hyperon directed flow measurement with the CBM experiment at the future FAIR facility in Darmstadt. Kalman Filter mathematics is used to reconstruct $\mathsf{\Lambda }\to p{\pi }^{-}$ weak decay kinematics, while the Particle Finder Simple package is used to optimize criteria for $\mathsf{\Lambda }$ hyperon candidate selection. Directed flow of $\mathsf{\Lambda }$ hyperons is studied as a function of rapidity, transverse momentum and collision centrality. The effects on flow measurement due to non-uniformity of the CBM detector response in the azimuthal angle, transverse momentum and rapidity are corrected using the QnTools analysis framework. Full article

The Compressed Baryonic Matter (CBM) experiment at the future Facility for Antiproton and Ion Research (FAIR) in Darmstadt is designed to investigate the properties of high-density QCD matter with multi-differential measurements of hadrons and leptons, including rare probes such as multi-strange anti-hyperons and charmed particles. The research program covers the study of the high-density equation-of-state of nuclear matter and the exploration of the QCD phase diagram at large baryon chemical potentials, including the search for quark matter and the critical endpoint of a hypothetical 1st order phase transition. The CBM setup comprises detector systems for the identification of charged hadrons, electrons, and muons; for the determination of collision centrality and the orientation of the reaction plane; and a free-streaming data read-out and acquisition system, which allows online reconstruction and selection of events up to reaction rates of 10 MHz. In this article, emphasis is placed on the measurement of muon pairs in Au-Au collisions at FAIR beam energies, which are unique probes used to determine the temperature of the fireball, and hence to search for a caloric curve of QCD matter. Simultaneously, the subthreshold production of charmonium can be studied via its dimuon decay in order to shed light on the microscopic structure of QCD matter at high baryon densities. The CBM setup with focus on dimuon measurements and the results of the corresponding physics performance studies will be presented. Full article

As a part of the future upgrade program of the Multi-Purpose Detector (MPD) experiment at the Nuclotron-Based Ion Collider Facility (NICA) complex, an Inner Tracking System (ITS) made of Monolitic Active Pixel Sensors (MAPSs) is proposed between the beam pipe and the Time Projection Chamber (TPC). It is expected that the new detector will enhance the experimental potential for the reconstruction of short-lived particles—in particular, those containing the open charm particle. To study the detector performance and select its best configuration, a track reconstruction approach based on a constrained combinatorial search was developed and implemented as a software toolkit called Vector Finder. This paper describes the proposed approach and demonstrates its characteristics for primary and secondary track finding in ITS, ITS-to-TPC track matching and hyperon reconstruction within the MPD software framework. The results were obtained on a set of simulated central gold–gold collision events at $\sqrt{s_{NN}}=9$ GeV with an average multiplicity of ∼1000 charged particles in the detector acceptance produced with the Ultra-Relativistic Quantum Molecular Dynamics (UrQMD) generator. Full article

At the Large Hadron Collider (LHC) a significant production of (anti-)(hyper-)nuclei is observed in proton-proton (pp), proton-lead (p-Pb) and lead-lead (Pb-Pb) collisions. The measurement of the production yields of light (anti-)nuclei is extremely important to provide insight into the production mechanisms of nuclear matter, which is still an open question in high energy physics. The outstanding particle identification (PID) capabilities of the ALICE detectors allow the identification of rarely produced particles such as deuterons, ${}^3\mathrm{He}$ and their antiparticles. From the production spectra measured for light (anti-)nuclei with ALICE, the key observables of the production mechanisms (antimatter/matter ratio, coalescence parameter, nuclei/protons ratio) are computed and compared with the available theoretical models. Another open question is the determination of the hypertriton lifetime: published experimental values show a lifetime shorter than the expected one, which should be close to that of the free $\Lambda$ hyperon. Thanks to the high-resolution track reconstruction capabilities of the ALICE experiment, it has been possible to determine the hypertriton lifetime at the highest Pb-Pb collisions energy with the highest precision ever reached. Full article