22.6.2021 A colourful look at fast-flying particles (Ramnath)

The strong nuclear force is one of the four fundamental forces of nature, along with the electromagnetic, gravitational and weak nuclear forces. The branch of particle physics that deals with the strong nuclear force is called quantum chromodynamics (QCD). The term “chromo” refers to the charge in the theory, which is called colour (not related to the everyday meaning of the word in terms of visible light). It is important to understand more about QCD, since it gives us a better understanding of nature as a whole and of the universe we occupy.
Published
22.6.2021

This thesis develops new equations that describe how quantities measured in experiments depend on energy. One such equation describes the energy dependence of the “odderon”, a particle that has been made famous in international news recently due to its observation at CERN in late 2020. We also use a new method to calculate evolution equations without making the usual assumption that QCD has infinitely many colours, instead of the three colours it has in reality.

It is very difficult to directly measure quarks and gluons, because they only occur in bound states, such as the proton. However, this is possible at high energy particle colliders such as the LHC (Large Hadron Collider) at CERN (European Organisation for Nuclear Research) and RHIC (Relativistic Heavy Ion Collider) at BNL (Brookhaven National Laboratory) and the future EIC (Electron-Ion Collider). These large machines can accelerate particles to close to the speed of light, giving access to the short length scales where quarks and gluons can be seen.

QCD is a theory where it is difficult to make theoretical predictions for and analyse the data from experiments. This thesis uses an effective theory formulation for the high energy limit called the Colour Glass Condensate (CGC). In this theory, we consider the collision between any hadron or nucleus (called the “target”) with any type of other particle (called the “projectile”).

The target is modelled as a dense, pancake-like structure consisting of quarks and gluons, travelling at a very high speed towards the projectile. This medium is what is called the CGC. In this thesis, we examine the interaction between the target and the projectile in certain specific instances that are relevant for particular collisions. The equations we study govern how these interactions change at diזּerent energy scales. The CGC is a novel and fast-growing field within the particle physics world.

The research is published in JYU Dissertation series, number 405, Ģֱ, Jyväskylä, 2021. 
ISBN 978-951-39-8750-3 (PDF), URN:ISBN:978-951-39-8750-3 and ISSN 2489-9003
Permanent link to this publication:

M.Sc. Andrecia Ramnath defends her doctoral dissertation "Nonlinear Evolution in the Colour Glass Condensate" at the Ģֱ on Tuesday 22nd of June 2021 starting at noon. Opponent is Associate Professor Stephane Munier (Ecole Polytechnique/CNRS, France) and Custos is Professor Tuomas Lappi from Ģֱ. The doctoral dissertation is held in English.

The audience can follow the dissertation online.
Link to the Zoom Webinar event (Zoom application or Google Chrome web browser recommended): 

Phone number to which the audience can present possible additional questions at the end of the event (to the custos): +358 40 727 4613