Quark Matter 2025

Session

Parallel session 28

9 Apr 2025, 08:40

Goethe University Frankfurt, Campus Westend, Theodor-W.-Adorno-Platz 1, 60629 Frankfurt am Main, Germany

Conveners

Parallel session 28: Jets IV

• James Lawrence Nagle (University of Colorado Boulder)

748. How loss of colour coherence affects intra-jet observables

Korinna Zapp

09/04/2025, 08:40

Jets

Oral

When a hard parton fragments in vacuum, subsequent emissions are angular ordered due to colour coherence. In contrast to this, in a dense coloured medium interactions with the background change the parton's colour and disrupt colour coherence. The phase space for the next emission is then not constrained by angular ordering leading to potentially measurable differences in the distribution of...

714. Gluon emission by a quark-antiquark antenna with realistic parton-medium interactions

André Cordeiro (LIP/IST)

09/04/2025, 09:00

Jets

Oral

The spectrum of coherent gluon radiation from a quark-antiquark pair experiencing multiple scatterings within a coloured medium is central for understanding in-medium parton cascades. Despite its foundational importance, current results are limited by reliance on simplified scattering rates, such as the harmonic oscillator approximation, valid only in restricted phase-space regions. Using the...

620. Jet Elliptic Anisotropy and Suppression in PbPb, AuAu and OO

Adam Takacs (Heidelberg University)

09/04/2025, 09:20

Jets

Oral

The elliptic anisotropy of energetic particles produced in heavy-ion collisions is understood as an effect of a geometrical selection bias due to energy loss. In the measured ensemble, particles oriented in the direction in which the medium is shorter are over-represented as compared to those oriented in the direction in which the medium is longer. In this work we present the first...

979. First measurement of full event energy-energy correlation in high-Z tagged events in PbPb collisions in CMS

Ms Yi Chen (Vanderbilt University (US))

09/04/2025, 09:40

Jets

Oral

The production of a Z boson provides a clean handle to control the population of events to be studied. By selecting muonic decays of Z bosons, we can isolate the effect of the recoiling process without potential bias from requiring isolation, as is the case for photons. Di-hadron correlations can naturally separate effects from different angular scales and enable jet substructure measurements...

975. First evidence of the medium response to hard probes with Z-hadron correlations in PbPb and pp collisions at $\sqrt{s_\mathrm{NN}} = 5.02$ TeV

Yen-Jie Lee (Massachusetts Inst. of Technology (US))

09/04/2025, 10:00

Jets

Oral

The first measurement of low transverse momentum ($p_\mathrm{T}$) charged hadron pseudorapidity and azimuthal angle distributions relative to $Z$ bosons in PbPb collisions at nucleon-nucleon center-of-mass energy $\sqrt{s_\mathrm{NN}} = 5.02$ TeV is presented. This study utilizes PbPb collision data recorded in 2018 with an integrated luminosity of $1.67 \pm 0.03$ nb$^{-1}$, as well as pp...

969. First measurement of jet axis decorrelation for detecting in-medium momentum broadening in photon-tagged jets PbPb at 5.02 TeV with CMS

Lida Kalipoliti (LLR, École Polytechnique (FR))

09/04/2025, 10:20

Jets

Oral

A search for medium-induced jet transverse momentum broadening is performed with isolated photon-tagged jet events in pp and PbPbcollisions at n5.02 TeV. The difference between jet axes as determined via energy-weight and winner-take-all clustering schemes, also known as the decorrelation of jet axes and denoted Δj, is measured for the first time in photon-tagged jet events. This observable is...