Conveners
Parallel Session T04: Jets, high-pT hadrons, and medium response: I
- Peter Levai (Wigner Research Centre for Physics (Wigner RCP) (HU))
Parallel Session T04: Jets, high-pT hadrons, and medium response: II
- Krzysztof Kutak (Instytut Fizyki Jadrowej Polskiej Akademii Nauk)
Parallel Session T04: Jets, high-pT hadrons, and medium response: III
- Dennis Perepelitsa (University of Colorado Boulder)
Parallel Session T04: Jets, high-pT hadrons, and medium response: IV
- Boris Tomasik (Univerzita Mateja Bela (SK))
Jets correlated with isolated photons are a promising channel to study jet quenching in heavy-ion collisions, as photons do not interact strongly and therefore constrain the $Q^2$ of the initial hard scattering. The measurement of isolated single photon production constrains NLO pQCD predictions and PDFs, and isolated photon production in Pb-Pb collisions is sensitive to initial geometrical...
Measurements of high $p_\mathrm{T}$ hadrons produced in hard scattering events offer insight to the modification of jet fragmentation and medium response of the quark-gluon plasma (QGP)
created in ultrarelativistic nucleus-nucleus collisions.
The hard scatter, tagged by an electroweak boson or a jet, fixes initial properties of the showering partons prior to interactions with the QGP. In...
Z bosons can be used to constrain the initial energy, direction, and the flavor of the recoiling parton before its interaction with the quark-gluon plasma. By measuring charged particle yields in Z boson events one can study the in-medium modifications of the recoiling parton showers and as well as the soft particles from medium response. The talk will present measurements of the azimuthal...
We report high-statistics measurements of semi-inclusive distributions of charged jets recoiling from high-$E_{\text{T}}$ direct photon ($\gamma_{\text{dir}}$) and $\pi^{0}$ triggers in $p$+$p$ and central Au+Au collisions at $\sqrt{s_{NN}} = 200$ GeV. In a semi-inclusive approach, event bias is induced solely by the choice of trigger; separately utilizing $\gamma_{\text{dir}}$ and $\pi^{0}$...
Experimentalists and theorists are pushing towards studying large radius jets in heavy ion collisions in an endeavour to decode signs of induced radiation and medium response with increasing precision. However, even at mid-rapidity, jets are not entirely composed of final state emissions, but contain a varying amount of initial state radiation. This contribution is small for small radius...
In this work, we introduce both gluon and quark degrees of freedom for describing the partonic cascades inside the medium. We present numerical solutions for the set of coupled evolution equations with splitting kernels calculated for the static, exponential and Bjorken expanding media to arrive at medium-modified parton spectra for quark and gluon initiated jets respectively. We discuss novel...
Even though QGP, when looked at on length scales of order the inverse of its temperature, is best described as a strongly coupled liquid, when it is observed at sufficiently short length scales or probed at sufficiently high exchanged-momentum, asymptotic freedom predicts the presence of quark-like and gluon-like quasi-particles. High energy partons (e.g. those in jet showers) traversing the...
It is well established that hard partons lose energy as they traverse the quark-gluon plasma (QGP). However, while there has been significant work to describe the mechanism by which this occurs, the relative contributions of the microscopic processes have yet to be constrained experimentally. One way to address this question is to exploit the theoretically derived relationship between the...
It has been shown that high-energy partons lose energy when traversing the hot, dense medium produced in heavy-ion collisions. However, the mechanism of the energy loss, including its dependence on the path-length of the shower in the medium and sensitivity to the jet substructure, is not fully understood. This talk presents a new measurement of single jet yields as a function of the azimuthal...
Jet quenching is a well-established signature of quark-gluon plasma formation in heavy ion collisions. Studies of the transverse momentum balance of back-to-back jets, as well as medium-induced modifications to jet shapes and fragmentation functions, provide important experimental constraints on quark-gluon plasma properties. Using a large sample of dijet events from 5.02 TeV PbPb and pp...
The upcoming run of oxygen-oxygen (OO) collisions at the LHC offers unique experimental and theoretical opportunities to address the long standing question of high-momentum rescattering (jet quenching) in small collision systems. We have demonstrated previously that even small energy loss effect can be observed in nuclear modification factor thanks to high precision pQCD baseline calculations...
While a variety of jet substructure measurements have been performed in heavy-ion collisions, a unified understanding of how the QGP affects the angular and momentum structure of jets remains an open question. One of the prominent puzzles is that measurements indicate no significant modification of the jet mass in heavy-ion collisions relative to proton-proton collisions, but significant...
High energy partons are well established to lose energy when traversing the hot and dense medium produced in heavy-ion collisions. This results in a modification to the transverse momentum distributions of jets, producing a phenomenon known as jet quenching. It has been previously established in Pb+Pb collisions at $\sqrt{s_\textrm{NN}}~=~2.76$~TeV that jet quenching results in significant...
The early production of heavy-flavour partons makes them an excellent probe of the dynamical evolution of QCD systems. Jets tagged by the presence of a heavy-flavour hadron give access to the kinematics of the heavy partons, and along with correlation measurements involving heavy-flavour hadrons allow for comparisons of their production, propagation, and fragmentation across different systems....
Transverse momentum broadening and energy loss of a propagating parton are dictated by the space-time profile of the jet transport coefficient $\hat{q}$ in a dense QCD medium. The spatial gradient of $\hat{q}$ perpendicular to the propagation direction can lead to a drift and asymmetry in parton transverse momentum distribution. Such an asymmetry depends on both the spatial position along the...
The jet quenching phenomenon, one of the signatures of the quark-gluon plasma, is well established through experimental measurements at RHIC and LHC. However, the details of the expected dependence of jet-medium interactions on the flavor of the parton initiating the shower are not yet settled. This talk presents the first b jet shapes measurements from 5 TeV PbPb and pp collisions collected...
In this contribution, the similarity between small and large collision systems will be further explored using the underlying event (UE) charged-particle density, $N_{\rm T}$ and the self-normalized version, $R_{\rm T}$. By selecting on $N_{\rm T}/R_{\rm T}$ and topological region, different microscopic processes contributing to the inclusive production can be isolated.
Final measurements of...
Jets have become a prominent tool for studying properties of the quark-gluon plasma through observations of in-medium modifications of parton showers and energy loss patterns in heavy-ion collisions. These effects, termed jet quenching, were expected to depend on the color-charge and/or flavor of the parton initiating the shower. The jet charge observable, defined as the momentum-weighted sum...
The JETSCAPE Collaboration reports a new determination of jet transport coefficients in the
Quark-Gluon Plasma, using both reconstructed jet and hadron data measured at RHIC and the
LHC. The JETSCAPE framework incorporates detailed modeling of the dynamical evolution of
the QGP; a multi-stage theoretical approach to in-medium jet evolution and medium response;
and Bayesian inference for...
In the last few years, several frameworks have achieved the evaluation of the medium-induced gluon radiation spectrum (or rate) with all-order resummation of multiple scatterings for static media. However, conceptual and computational issues arise when embedding approaches including multiple scatterings into dynamic plasmas. In this talk, we will show several paths to overcome these...
The suppression of jets in heavy-ion collisions provides a powerful method to probe the dynamics of the hot, dense plasma formed in these collisions at the LHC.
Jet quenching in heavy-ion collisions is expected to depend on the mass of the fragmenting parton as well as its QCD color charge.
For light quarks and gluons, energy loss via gluon bremsstrahlung, which is sensitive to the QCD color...
We show that the same QCD formalism that accounts for the suppression of high-$p_T$ hadron spectra in heavy-ion collisions predicts a medium-enhanced $c\bar{c}$ pair production in high-$p_T$ jets.
We found that collisional and radiative processes affect hadron and jet $R_{AA}$ with different $p_T$ dependence. It is then interesting to analyze the combined constraining power from both jet and hadron quenching to the jet transport parameter $\hat{q}$.
We conduct the study with the improved transport model (LIDO), including elastic and radiative processes, and a simple treatment of...
We compute the in-medium jet broadening $\langle p_\perp^2\rangle$ to leading order in energy in the opacity expansion. At leading order in $\alpha_s$ the elastic energy loss gives a jet broadening that grows with $\ln E$. The next-to-leading order in $\alpha_s$ result is a jet narrowing, due to destructive LPM interference effects, that grows with $\ln^2 E$. We find that in the opacity...
Jets in relativistic heavy-ion collisions interact with the quark-gluon plasma (QGP), leading to effects such as a suppression of jet yields and modification of internal jet structure that are used to measure the properties of the QGP. This talk will show the inclusive jet nuclear modification factors in Pb--Pb collisions in various centrality classes at $\sqrt{s_{\mathrm{NN}}}=5.02$ TeV...
Jets are excellent probes for the study of the deconfined matter formed in heavy ion collisions. We present measurements of the semi-inclusive distribution of charged-particle jets recoiling from a high-pT trigger hadron in pp and central Pb--Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 5.02 TeV. We compare the semi-inclusive recoil jet yields in pp and Pb-Pb collisions over a broad...
PHENIX has quantified the modification of jets in heavy-ion collisions due to partonic energy loss in the quark gluon plasma (QGP) by measuring the distribution of hadrons relative to a trigger particle, such as a high momentum photon or $\pi^{0}$. These two-particle correlations have revealed that high momentum hadrons are suppressed, while yield of low momentum hadrons is enhanced. This...
