Eccentricity fluctuations make flow measurable in high multiplicity p-p collisions

Area of Science:

• High Energy Physics
• Nuclear Physics
• Quantum Chromodynamics

Background:

• Elliptic flow is a primary observable for studying the collective behavior of matter created in high-energy particle collisions.
• Current measurement techniques for elliptic flow necessitate high event multiplicity, limiting their application to heavy-ion collisions.
• Upcoming experiments at the Large Hadron Collider (LHC) will generate substantial datasets of high-multiplicity proton-proton (p-p) collisions.

Purpose of the Study:

• To determine the conditions under which elliptic flow can be reliably measured in high-multiplicity p-p collisions.
• To explore the potential for observing collectivity in p-p interactions at the LHC.
• To establish the feasibility of applying standard elliptic flow analysis techniques to p-p collision data.

Main Methods:

• Analysis of simulated high-multiplicity p-p collision events with specific multiplicity thresholds (dN(ch)/dy >= 50).
• Investigation of the role of initial-state spatial eccentricity fluctuations in central p-p collisions.
• Application of standard elliptic flow measurement techniques under defined assumptions about fluctuation characteristics and flow scaling.

Main Results:

• Fluctuations within the p-p interaction region can lead to significant spatial eccentricity, even in the most central collisions.
• Under mild assumptions, the elliptic flow signal in high-multiplicity p-p collisions at the LHC is found to be measurable.
• The study demonstrates the potential for detecting collectivity in p-p collisions using established methods.

Conclusions:

• High-multiplicity p-p collisions at the LHC offer a new frontier for studying collective phenomena.
• The measurement of elliptic flow in p-p collisions is feasible with current analysis techniques.
• This opens avenues for comparing collectivity in different collision systems (p-p vs. heavy ions).