Disentangling sources of momentum fluctuations in heavy-ion collisions with the ATLAS detector

by Somadutta Bhatta

Tuesday 10 Sept 2024, 11:00 → 13:00 US/Eastern

Room 3-192

The event-by-event variation in the initial conditions and subsequent expansion of the Quark-Gluon Plasma (QGP) directly influences the distribution of the event-averaged transverse momentum ($[p_{\mathrm{T}}]$) of particles. Typically, the contributions to the transverse momentum from radial flow velocity and thermal component (from kinetic freezeout temperature) are extracted using simultaneous Blast-Wave fits to $p_{\mathrm{T}}$ spectra of identified hadrons. However, disentangling the contributions on an event-by-event basis arising from fluctuations in the overlap area (geometrical component) from other sources at fixed geometry (intrinsic component) remains a challenge.
In this talk, I will present new, precise ATLAS measurements of $[ p_\mathrm{T}]$ cumulants up to third order in heavy-ion collisions as a new tool to disentangle Geometric and Intrinsic fluctuations. The observables exhibit distinct behavior, particularly in ultra-central collisions where geometrical variations are suppressed as the overlap area reaches its maximum. These measurements provide the first experimental means to disentangle different sources of fluctuations arising from the initial state and medium evolution, offering new constraints on key properties of the QGP, such as the speed of sound.



How to get to the seminar room 3-192:

In order to get here take a look at the floor plan
https://www.phy.bnl.gov/DepartmentDirectory/searchDirectory.php

Find your way to the building which has the third floor and then follow this:
https://www.phy.bnl.gov/DepartmentDirectory/floorplan.php?floor=3