#### Alladi Ramakrishnan Hall

#### Soft-Collinear Effective Theory

#### Ankita Budhraja

##### Indian Institute of Science Education and Research, Bhopal

*Effective field theories provide a powerful framework to exploit a separation of scales in physical systems. Over the centuries we have been utilizing these ideas and studying the world around us, discovering new physics at new length scales. In this talk, I will discuss some general aspects of effective field theories using a simple toy model and describe some examples of the popularly studied effective theories in particle physics. In particular, I will consider an effective field theory for Quantum Chromodynamics (QCD) known as the Soft-Collinear Effective Theory (SCET), relevant for describing processes containing energetic particles. I will discuss in full detail the construction of the leading-order Lagrangian of SCET and then utilize it for the specific case of a popular event shape observable thrust relevant for jet processes. These jet observables are often plaqued with the appearance of large logarithms when computed in the fixed-order perturbation theory and hence demand an all-order summation of logarithms to obtain predictive theoretical results that can be matched against experimental data. For the thrust observable, I will also describe how this all-order summation is achieved within the effective theory approach.*

Done