## Theoretical Physics

## Research Topics

## Field Theory and String Theory

**S. Penati, A. Tomasiello, A. Zaffaroni, S. Pasquetti, N. Mekareeya**

Our group focuses on the problem of finding a quantum theory of gravity, and of unifying it with the other elementary interactions. There are several reasons to think that the right candidate might be string theory, whose study is still in progress. Its basic assumption is that the fundamental constituents of the world are not pointlike, but rather extended one–dimensional objects: "strings". We also study more traditional quantum field theories, some of which are related to string theory via the so–called AdS/CFT correspondence.

## Standard Model Quantum Field Theory

**P. Nason, C. Oleari, S. Alioli, E.Re**

Our field of study is Quantum Chromo--Dynamics (QCD), the relativistic quantum theory of the strong interaction. Because of its complexity, this theory can only be approached with suitable approximation techniques. For some problems, such as scatterings at very high energies, various perturbation theory schemes are available. We are also interested in several aspects of the Standard Model of fundamental interactions, which provides a unified description of the electromagnetic and weak interactions of quarks and leptons. In spite of the successes of this model, there are many reasons to think it is actually incomplete, and that it will have to be extended to a complete unification of the fundamental forces. In particular, supersymmetry, a hypothetical new symmetry that would relate elementary forces and matter particles, is a candidate for such future developments.

## Non-perturbative Quantum Field theory and Computational Physics

**M. Bruno, C. Destri, L. Giusti, M. Pepe, F. Rapuano**

We study relativistic quantum field theories non-perturbatively. This is required for the theoretical understanding of many phenomena in Physics where the interactions among the fundamental constituents are strong.

In the Standard Model of Particle Physics, Quantum Chromodynamics (QCD) is the fundamental theory of the Strong Interactions that describes the dynamics of quarks and gluons: it determines, for instance, the properties and the structure of hadrons, the features of the quark-gluon plasma at high temperature, and in flavour physics it is instrumental in the derivation of precise predictions from the Standard Model and beyond. We are particularly interested in processes that may shed light on several weaknesses of the Standard Model, and possibly reveal the existence of new fundamental degrees of freedom in Nature, such as the anomalous magnetic moment of leptons, rare hadronic decays, weak and strong CP violation. In order to define non-perturbatively the relevant quantum field theories, the four-dimensional space-time has to be discretized on a lattice. Once the quantities of interest have been defined non-perturbatively in a rigorous way, they are computed on the fastest High-Performance Computers (HPC) made available by the European supercomputing centers. To this aim specialized algorithms and computational strategies are constantly developed within our group, together with highly-optimized codes and software which are created, tested and refined on locally assembled and managed small-scale HPC clusters.

### The String Theory Group in Milan-Bicocca invites applications for two/three postdoctoral positions starting in Autumn 2022

**One two-year post-doctoral position**funded by the INFN grant GSS with research theme: “Dualities, non-perturbative phenomena in Quantum Field Theory and black holes”.

Application should be submitted through the central INFN website, under “Assegni Post Doctoral Teorici”, bando/call 23590.

The call is for 16 positions and you should explicitly select Milano-Bicocca if you are interested to come to Milano-Bicocca.

Notice the early deadline November 9th! Notice also that applications through the Central European String Theory Website are not valid for this position.

Please feel free to contact us for more information (alberto.zaffaroni@mib.infn.it).**One/two two-year positions**on the research theme “Non-perturbative QFT, dualities, boundaries and defects”. Candidates should submit their applications via the common Central European String Theory Website https://itf.fys.kuleuven.be/postdoc-application indicating their preference for Milano-Bicocca. We accept applications only through this website.

Letters of Reference should be sent to: https://itf.fys.kuleuven.be/postdoc-application/

Please feel free to contact us for more information (sara.pasquetti@gmail.com, silvia.penati@mib.infn.it).