Three-particle correlations with respect to strangeness in pp colllisions
(2026) FYSM64 20261Department of Physics
Particle and nuclear physics
- Abstract
- High-energy proton-proton collisions such as the ones happening at the LHC can result in the formation of the QGP, a state of matter similar to the early Universe's. One property of the QGP is strangeness enhancement, leading to the formation of strange flavoured particles such as $\Xi$, $\Lambda$ or $K$. The aim of this thesis is to study the production mechanism of a strangeness-balanced triplet ($\Xi^-K^+K^+$) through its angular correlation functions and balance function. This is done through the use of Monte-Carlo generated data using the PYTHIA software, as well as real data from the CERN ALICE experiment. Data is then analysed using the ROOT framework in both cases. Final results provide us with a negative ridge along the values... (More)
- High-energy proton-proton collisions such as the ones happening at the LHC can result in the formation of the QGP, a state of matter similar to the early Universe's. One property of the QGP is strangeness enhancement, leading to the formation of strange flavoured particles such as $\Xi$, $\Lambda$ or $K$. The aim of this thesis is to study the production mechanism of a strangeness-balanced triplet ($\Xi^-K^+K^+$) through its angular correlation functions and balance function. This is done through the use of Monte-Carlo generated data using the PYTHIA software, as well as real data from the CERN ALICE experiment. Data is then analysed using the ROOT framework in both cases. Final results provide us with a negative ridge along the values where the difference in azimuthal angle and pseudorapidity are equal between the $\Xi^-$ and both kaons. This result can be explained by uncorrelated remnants from two-particle correlations that have not been sufficiently corrected through mixed events. A biased simulation also provides us with an expected production mechanism favouring the production of the particles in the triplets close to each other in angular coordinates, raising the need for further analysis to improve event mixing corrections. (Less)
- Popular Abstract
- Our world is made of matter composed of different layers, similarly to Matryoshka dolls. A material is made of atoms, which are made of smaller particles, such as electrons with negative charge or nucleons. Nucleons are either protons with positive charge or neutrons without charge. They are themselves made of smaller particles called quarks, which exist in different types in nature. Quarks cannot however exist freely, they are bound mainly in pairs or triplets called hadrons. The set of all the elementary particles (hence what we know are the smallest particles possible) is called the Standard Model.
Particles in the Standard Model are subject to different forces: the electromagnetic force, the weak force and the strong force. In the... (More) - Our world is made of matter composed of different layers, similarly to Matryoshka dolls. A material is made of atoms, which are made of smaller particles, such as electrons with negative charge or nucleons. Nucleons are either protons with positive charge or neutrons without charge. They are themselves made of smaller particles called quarks, which exist in different types in nature. Quarks cannot however exist freely, they are bound mainly in pairs or triplets called hadrons. The set of all the elementary particles (hence what we know are the smallest particles possible) is called the Standard Model.
Particles in the Standard Model are subject to different forces: the electromagnetic force, the weak force and the strong force. In the case of proton-proton collisions at high energies, such as the collisions happening at the LHC (Large Hadron Collider), the strong force dominates the other ones. In the strong interaction sector, the very high temperature reached during collisions allows the formation of the Quark Gluon Plasma (QGP), a state of matter similar to the early Universe medium. One key property of the QGP is strangeness enhancement, the production of a large number of strange quarks, which will then form hadrons.
When a quark is created, it has a twin sibling, an anti-quark, which shares the same mass but has an opposite charge. It is possible for bound particles to split following the Lund String Model: quarks combinations are assumed to behave like strings with particles at each end. Quarks’ energies will transfer to string which will elongate further and further, until reaching a breaking point. Similarly to an elastic breaking, the quarks will be projected with high momenta. When encountering a quark that has been subject to the same phenomenon, a fleeing quark will once again bind with this new partner, creating a new hadron.
This thesis focuses on the study of strange flavoured hadrons. When a quark and anti-quark pair is separated through string breaking, the quarks remain correlated. The objective of our work is then to find which particle is correlated with which, hence finding which particles are created from the initial strange quark and anti-quark pair. This is achieved by studying angular correlations, namely how the angular coordinates of each particle behave with respect to each other.
In order to study particle correlations, we firstly in the thesis use simulated data. This data set is obtained using the PYTHIA program, an event generator for high-energy collision events, based on the Lund String Model. Running simulations allows us to know precisely what particle is created during the proton-proton collision for a similar experimental process, hence providing us with what could be expected with real data. The real data analysis is performed with data provided by A Large Ion Collider Experiment (ALICE) from the LHC, located at CERN in Geneva, allowing us to study three-particle correlations with respect to strangeness. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/student-papers/record/9241875
- author
- Vernanchet, Adrien Julien LU
- supervisor
-
- Alice Ohlson LU
- organization
- course
- FYSM64 20261
- year
- 2026
- type
- H2 - Master's Degree (Two Years)
- subject
- keywords
- Correlations, Balance functions, Strangeness, Angular parameters, Monte-Carlo, ALICE
- language
- English
- id
- 9241875
- date added to LUP
- 2026-06-19 17:48:05
- date last changed
- 2026-06-19 17:48:05
@misc{9241875,
abstract = {{High-energy proton-proton collisions such as the ones happening at the LHC can result in the formation of the QGP, a state of matter similar to the early Universe's. One property of the QGP is strangeness enhancement, leading to the formation of strange flavoured particles such as $\Xi$, $\Lambda$ or $K$. The aim of this thesis is to study the production mechanism of a strangeness-balanced triplet ($\Xi^-K^+K^+$) through its angular correlation functions and balance function. This is done through the use of Monte-Carlo generated data using the PYTHIA software, as well as real data from the CERN ALICE experiment. Data is then analysed using the ROOT framework in both cases. Final results provide us with a negative ridge along the values where the difference in azimuthal angle and pseudorapidity are equal between the $\Xi^-$ and both kaons. This result can be explained by uncorrelated remnants from two-particle correlations that have not been sufficiently corrected through mixed events. A biased simulation also provides us with an expected production mechanism favouring the production of the particles in the triplets close to each other in angular coordinates, raising the need for further analysis to improve event mixing corrections.}},
author = {{Vernanchet, Adrien Julien}},
language = {{eng}},
note = {{Student Paper}},
title = {{Three-particle correlations with respect to strangeness in pp colllisions}},
year = {{2026}},
}