arXiv subjects

David Tlusty

Publications and source records attributed to David Tlusty.

7 recordsLinked to original sources

arXiv2026

Performance of the Endcap Time-of-Flight detector in the STAR beam-energy scan

The STAR experiment at RHIC at Brookhaven National Laboratory completed the installation of an endcap time-of-flight subsystem (eTOF) in February 2019. The eTOF subsystem provided essential mid-rapidity particle identification (PID) for the fixed-target (FXT) portion of phase II of the beam energy scan (BES II). The FXT program allowed BES II to include center-of-mass energies from $\sqrt{s_{_{NN}}} = 3.0$ GeV to $\sqrt{s_{_{NN}}} = 7.7$ GeV, not accessible by colliding beams. The eTOF detectors and readout electronics were designed for the CBM experiment at FAIR and adapted for use at STAR. In this paper, we describe the details of the system in terms of geometrical layout, acceptance, calibration, hit reconstruction, and particle identification. The system achieved a time resolution of about 70 ps and a PID efficiency of about 70\%, meeting the design goals of the project.

physics.ins-det↗

arXiv2025

AI-powered full-data set search for new physics in ultraperipheral and diffractive events

We present possible strategies for anomaly detection of rare particle decays and exotic hadrons, such as pentaquarks, in low-background environments such as those characteristic of diffractive events and ultraperipheral \pp, \pA, or \AAcoll collisions at the CERN Large Hadron Collider (LHC). Our models are trained with toy samples representing the UPC processes measured until now by the ALICE Collaboration. When samples containing rare processes such as $\jpsi\rightarrow4\pi$ and pentaquark production, where the number of injected pentaquark events is estimated based on current experimentally available upper limits, and those for $\jpsi\rightarrow4\pi$ are estimated through the branching ratio of the decay channel, are analyzed, the rare processes are flagged as anomalous by the models. This approach demonstrates the applicability of such a technique for searches for new physics in the current and future data sets at collider experiments with high purity, while also allowing for the measurement of upper limits for the production of exotica.

hep-ph↗

arXiv2025

STAR UPC Results

Relativistic heavy ions are sources of strong electromagnetic fields which produce photon-induced interactions. These interactions are usually studied in ultra-peripheral collisions (UPCs) of the relativistic heavy ions. The UPCs can produce di-lepton or di-hadron pairs via the $\gamma-\gamma$ interactions or produce vector mesons via the $\gamma-$nuclear interactions. Both the photo-produced vector mesons and the lepton/hadron pairs productions depend on the original electromagnetic field. In addition, the photo-produced vector mesons are sensitive to the gluon parton distribution of the entire target nucleus (coherent production) or the individual nucleons (incoherent production). In these proceedings, recent STAR results on vector mesons, di-lepton pairs, and di-hadron photo-production will be discussed. The measurements are compared with available models to discuss the relevant implications.

hep-ex↗

arXiv2024

Machine learning opportunities for online and offline tagging of photo-induced and diffractive events in continuous readout experiments

The increasing data rates in modern high-energy physics experiments such as ALICE at the LHC and the upcoming ePIC experiment at the Electron-Ion Collider (EIC) present significant challenges in real-time event selection and data storage. This paper explores the novel application of machine learning techniques, to enhance the identification of rare low-multiplicity events, such as ultraperipheral collisions (UPCs) and central exclusive diffractive processes. We focus on utilising machine learning models to perform early event classification, even before full event reconstruction, in continuous readout systems. We estimate data rates and disk space requirements for photoproduction and central exclusive diffractive processes in both ALICE and ePIC. We show that machine learning techniques can not only optimize data selection but also significantly reduce storage requirements in continuous readout environments, providing a scalable solution for the upcoming era of high-luminosity particle physics experiments.

hep-ex↗

arXiv2018

The RHIC Beam Energy Scan Phase II: Physics and Upgrades

The exploration of the QCD phase diagram has been one of the main drivers of contemporary nuclear physics. The Relativistic Heavy Ion Collider (RHIC) at BNL is uniquely suited for this task through its Beam Energy Scan (BES) program which allowed for a large range in baryon chemical potential $μ_B$ as was successfully demonstrated after the completion of Phase 1 in 2014. Phase 2 of the BES at RHIC is scheduled to start in 2019 and will explore with precision measurements the intermediate-to-high $μ_B$ region of the QCD phase diagram, five energies $\sqrt{s_{NN}}$ from 7.7 to 19.6 GeV in collider mode and eight energies $\sqrt{s{_{NN}}}$ from 3.0 to 7.7 GeV in fixed-target mode. Some of the key measurements are: the net-protons kurtosis that could pinpoint the position of a critical point, the directed flow that might prove a softening of the EOS, and the chiral restoration in the dielectron channel. These measurements will be possible with an order of magnitude better statistics provided by the electron cooling upgrade of RHIC and with the detector upgrades planned to improve STAR's acceptance. These proceedings review the BES Phase-2 program and the physics opportunities enabled by these upgrades.

nucl-ex↗

arXiv2012

Open charm hadron production via hadronic decays at STAR

In this article, we report on the STAR results of open charm hadron production at mid-rapidity in $p+p$ and Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV and $p+p$ collisions at $\sqrt{s}$ = 500 GeV. The measurements cover transverse momentum range from 0.6 to 6 GeV/c for $p+p$ 200 GeV collisions, from 1 to 6 GeV/c for $p+p$ 500 GeV collisions and from 0 to 6 GeV/c for Au+Au 200 GeV collisions. $D^0$ nuclear modification factor and elliptic flow in Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV are presented.

hep-ex↗

arXiv2012

Open charm hadron production via hadronic decays at STAR

Heavy quarks are a unique probe to study the medium produced in ultra-relativistic heavy ion collisions. The dominant process of charm quark production at RHIC is believed to be initial gluon fusion which can be calculated in the perturbative QCD. The upper limit of FONLL calculation seems to be in good agreement with charm cross section measurements at mid-rapidity in $p+p$ collisions at $\sqrt{s_{NN}}$ = 200 GeV provided by STAR. The same measurement in Au+Au collisions at equal energy reveals the number-of-binary-collisions scaling of charm cross section indicating that charm production is dominated by initial hard scatterings. In this article, we report the measurements of $D^{0}$, $D^{*}$ in $p+p$ at 0.6 GeV/$c < p_T < 6$ GeV/$c$ and $D^0$ in Au+Au collisions at 0.2 GeV/$c < p_T < 5$ GeV/$c$ via hadronic decays $D^{0}\rightarrow K^-π^+,\ D^{*+}\rightarrow D^0π^+\rightarrow K^-π^+π^+$ at mid-rapidity $|y|<1$. {abstract}

hep-ex↗