M. Heffernan
A5046662880- High-Energy Particle Collisions Research
- Quantum Chromodynamics and Particle Interactions
- Particle physics theoretical and experimental studies
- Nuclear physics research studies
- Statistical Methods and Bayesian Inference
- Statistics Education and Methodologies
- Dark Matter and Cosmic Phenomena
- Experimental and Theoretical Physics Studies
- Black Holes and Theoretical Physics
- Bayesian Methods and Mixture Models
- Nuclear reactor physics and engineering
- Cosmology and Gravitation Theories
- Gaussian Processes and Bayesian Inference
- Advanced X-ray and CT Imaging
- High-pressure geophysics and materials
McGill University
2020-2024
Williams (United States)
2015
Texas A&M University
2015
William & Mary
2015
We study the properties of strongly-coupled quark-gluon plasma with a multistage model heavy ion collisions that combines T$_\mathrm{R}$ENTo initial condition ansatz, free-streaming, viscous relativistic hydrodynamics, and hadronic transport. A model-to-data comparison Bayesian inference is performed, revisiting assumptions made in previous studies. The role parameter priors studied light their importance towards interpretation results. emphasize use closure tests to perform extensive...
Using combined data from the Relativistic Heavy Ion and Large Hadron Colliders, we constrain shear bulk viscosities of quark-gluon plasma (QGP) at temperatures ∼150–350 MeV. We use Bayesian inference to translate experimental theoretical uncertainties into probabilistic constraints for viscosities. With model averaging propagate an estimate uncertainty generated by transition hydrodynamics hadron transport in plasma's final evolution stage, providing most reliable phenomenological date on...
We report a new determination of $\stackrel{\ifmmode \hat{}\else \^{}\fi{}}{q}$, the jet transport coefficient quark-gluon plasma. use JETSCAPE framework, which incorporates novel multistage theoretical approach to in-medium evolution and Bayesian inference for parameter extraction. The calculations, based on Matter Lbt quenching models, are compared experimental measurements inclusive hadron suppression in $\mathrm{Au}+\mathrm{Au}$ collisions at BNL Relativistic Heavy Ion Collider (RHIC)...
We present a new study of jet interactions in the quark-gluon plasma created high-energy heavy-ion collisions, using multistage event generator within jetscape framework. focus on medium-induced modifications rate inclusive jets and high transverse momentum (high-${p}_{\mathrm{T}}$) hadrons. Scattering-induced energy loss is calculated two stages: virtuality stage based matter model, which scattering highly virtual partons modifies vacuum radiation pattern, second at lower lbt leading gain...
The authors perform rigorous Bayesian inference on a variety of measurements in relativistic Pb-Pb collisions at the LHC using comprehensive multistage model combining QCD-based initial states with viscous hydrodynamics and hadronic afterburner. In particular, they extracted systematic constraints temperature dependence shear bulk viscosities quark-gluon plasma that are significantly more precise due to improved physical models statistical methods. For range probed heavy-ion collisions, find...
In ultrarelativistic heavy-ion collisions, a plasma of deconfined quarks and gluons is formed within 1 fm/c the nuclei's impact. The complex dynamics collision before ≈1 often described with parametric models, which affect predictivity calculations. this work, we perform systematic analysis LHC measurements from Pb-Pb by combining an ab initio model early stage collisions hydrodynamic plasma. We obtain state-of-the-art constraints on shear bulk viscosity quark-gluon mitigate additional cost...
Electromagnetic (EM) radiation off strongly interacting matter created in high-energy heavy-ion collisions (HICs) encodes information on the high-temperature phases of nuclear matter. Microscopic calculations thermal EM emission rates are usually rather involved and not readily accessible to broad applications models fireball evolution which required compare with experimental data. An accurate universal parametrization microscopic is thus key honing theory behind spectra. Here we provide...
Measurements from the Large Hadron Collider (LHC) and Relativistic Heavy Ion (RHIC) can be used to study properties of quark-gluon plasma. Systematic constraints on these must combine measurements different collision systems methodically account for experimental theoretical uncertainties. Such studies require a vast number costly numerical simulations. While computationally inexpensive surrogate models ("emulators") efficiently approximate predictions heavy ion simulations across broad range...
Parton energy-momentum exchange with the quark gluon plasma (QGP) is a multi-scale problem. In this work, we calculate interaction of charm quarks QGP within higher twist formalism at high virtuality and energy using MATTER model, while low portion treated via (linearized) Boltzmann Transport (LBT) formalism. Coherence effect that reduces medium-induced emission rate in model also taken into account. The interplay between these two formalisms studied detail used to produce good description...
We investigate general frameworks for calculating transport coefficients quasiparticle theories at finite temperature. Hadronic are then computed using the linear sigma model (LSM). The bulk viscosity over entropy density ($\zeta/s$) is evaluated in relaxation time approximation (RTA) and specific shear ($\eta/s$) static electrical conductivity ($\sigma_{el}/T$) both obtained RTA a functional variational approach. Results shown different values of scalar-isoscalar hadron vacuum mass with...
A global Bayesian analysis of relativistic Pb + collisions at $\sqrt{s}_{\rm NN}$ = 2.76 TeV is performed, using a multistage model consisting an IP-Glasma initial state, viscous fluid dynamical evolution, and hadronic transport final state. The observables considered are from the soft sector Posterior Maximum Posteriori parameter distributions that pertain to hydrodynamic phases obtained, including shear bulk specific viscosity strong interacting matter. first use inference with transfer...
We present predictions and postdictions for a wide variety of hard jet-substructure observables using multistage model within the framework. The details various parameter choices are described in []. A novel feature this is presence two stages jet modification: high-virtuality phase [modeled modular all twist transverse-scattering elastic-drag radiation ()], where modified coherence effects diminish medium-induced radiation, lower virtuality linear Boltzmann transport parton splits fully...
We perform the first quantitative study of sensitivity Big Bang Nucleosynthesis to variations in isospin breaking with precise input from lattice QCD calculations. The predicted light nuclear abundances are most sensitive neutron-proton mass splitting as both initial relative abundance neutrons protons and $n \rightleftharpoons p$ weak reaction rates very this quantity. Lattice has been used determine greater than 5-sigma, including contributions down-quark up-quark splitting, $2δ= m_d-m_u$...
We present a multi-stage model for jet evolution through quark-gluon plasma within the JETSCAPE framework. The approach in provides unified description of distinct phases shower contingent on virtuality. demonstrate simultaneous leading hadron and integrated observables as well $v_n$ using tuned parameters. Medium response to quenching is implemented based weakly-coupled recoil prescription. also explore cone-size dependence energy loss inside plasma.
"Hybrid Hadronization" is a new Monte Carlo package to hadronize systems of partons. It smoothly combines quark recombination applicable when distances between partons in phase space are small, and string fragmentation appropriate for dilute parton systems, following the picture outlined by Han et al. [PRC 93, 045207 (2016)]. Hybrid Hadronization integrates with PYTHIA 8 can be applied variety from $e^++e^-$ $A+A$ collisions. takes their color flow information, example shower generator, as...
In ultrarelativistic heavy-ion collisions, a plasma of deconfined quarks and gluons is formed within $1$ fm/c the nuclei's impact. The complex dynamics collision before $\approx 1$ often described with parametric models, which affect predictivity calculations. this work, we perform systematic analysis LHC measurements from Pb-Pb by combining an \emph{ab-initio} model early stage collisions hydrodynamic plasma. We obtain state-of-the-art constraints on shear bulk viscosity quark-gluon...
It is now well established that jet modification a multistage effect; hence single model alone cannot describe all facets of modification. The JETSCAPE framework uses several modules to simulate different stages propagation through the QGP medium. These simulations require set parameters ensure smooth transition between stages. We fine tune these successfully variety observables, such as nuclear factors leading hadrons and jets, shape, fragmentation function. Photons can be produced in hard...
The dynamics of shower development for a jet traveling through the QGP involves variety scales, one them being heavy quark mass. Even though mass quarks plays subdominant role during high virtuality portion evolution, it does affect longitudinal drag and diffusion, stimulating additional radiation from quarks. These emissions partially compensate reduction in dead cone effect. In lower part shower, when is comparable to transverse momenta partons, scattering processes off differ those light...
We present a new determination of $\hat{q}$, the jet transport coefficient quark-gluon plasma. Using JETSCAPE framework, we use Bayesian parameter estimation to constrain dependence $\hat{q}$ on energy, virtuality, and medium temperature from experimental measurements inclusive hadron suppression in Au-Au collisions at RHIC Pb-Pb LHC. These results are based multi-stage theoretical approach in-medium evolution with MATTER LBT quenching models. The functional is perturbative picture...