Fundamental Interactions and Astrophysics

The ALADDIN proposed experiment [1] at CERN LHC aims to measure for the first time the magnetic and electric dipole moments of the Lambda_c and Xi_c short-lived charmed baryons (average lifetime <0.5 ps), using innovative techniques. These moments will be derived from a measurement of the phase space distribution of the chrmed baryon decay products (3 charged particles), whose linear momenta will be measured with a magnetic spectrometer.

A Ring Imaging CHerenkov (RICH) detector much more performant than existing ones will allow to identify these charged particles up to very high momenta (several hundreds of GeV/c), providing an essential tool for background rejection.

A PhD student would have the opportunity to participate since the beginning to the process of designing  and building a particle detector with unprecedented performances, including laboratory tests of multi-channel photodetectors and their front-end electronics, beam tests of a reduced-size RICH prototype, data analysis and simulation studies.

References:
[1] ALADDIN Letter of Intent, CERN-LHCC-2024-011, LHCC-I-041 (2024), https://cds.cern.ch/record/2905467/files/LHCC-I-041.pdf

Heisenberg-Euler Lagrangians are effective theories, which encode Quantum Electro Dynamics (QED) non-linear effects, and are a helpful framework to describe various vacuum phenomena, i.e. light by light scattering, charge renormalization, vacuum decay effects (such as the Schwinger pair creation rate), just to name a few [1]. The computation of higher loop contributions, involving virtual photons, has been the subject of active research in the past few decades—see e.g. Ref. [2] and References therein. The present proposal aims to build on more recents work [3]—which found some two-loop (pure QED) contributions that had been previously overlooked—, in order to include contributions from other virtual particles, such scalars and/or gravitons, and eventually consider enhanced theories, constructed out of non-homogeneous electromagnetic backgrounds. The methodology used will involve both analytical methods and numerical techniques.

Collaborations:

Prof. Christian Schubert, Universidad Michoacana, Mexico

Prof. James P. Edwards, University of Plymouth, U.K.

Dr. Naser Ahmadiniaz, Helmholtz Center, Dresden, Germany

References

[1] G. Dunne, “Heisenberg-Euler effective Lagrangians: Basics and extensions,” doi:10.1142/9789812775344\_0014 [arXiv:hep-th/0406216 [hep-th]].

[2] G. Dunne and C. Schubert, “Two loop Euler-Heisenberg QED pair production rate,” Nucl. Phys. B564 (2000), 591-604, doi:10.1016/S0550-3213(99)00641-0, [arXiv:hep-th/9907190 [hep-th]].

[3] H. Gies and F. Karbstein, “An Addendum to the Heisenberg-Euler effective action beyond one loop,” JHEP 03 (2017) 108, doi:10.1007/JHEP03(2017)108, [arXiv:1612.07251 [hep-th]].

These Ph.D. projects explore one of the most exciting frontiers in contemporary astrophysics: how massive black holes influence the life cycle of galaxies and clusters of galaxies through their profound interaction with the surrounding cosmic medium. Far from being passive, black holes act as the beating hearts of galaxies, cosmic engines that regulate accretion and drive feedback, shaping the weather in the cosmic web.

In this Golden Age of black hole research, the following key areas will be investigated.

1. Gas Dynamics & Accretion: How hot halos cool and condense into multiphase gas and stars, and how this precipitation fuels black holes.

2. Feedback & Energy Injection: How black holes return energy via jets, winds, and radiation, transforming the thermodynamic state of galaxies and clusters.

3. Multiphysics Processes: The role of magnetic fields, conduction, and cosmic rays in mediating feeding and feedback, and shaping key observables.

4. Cosmic Evolution: How black hole processes impact galaxy formation and the growth of large-scale structures over cosmological times.

Two complementary methodologies can be pursued:

I. Simulations: High-resolution magneto-hydrodynamic simulations using next-generation GPU codes (e.g. AthenaPK) to model the turbulent, multiphase interplay of feeding and feedback.

II. Observations: Analysis of multiwavelength data from world-class facilities (Chandra, MUSE, JWST, ALMA, MeerKAT), supported by synthetic observations to enable direct theory-data comparison.

Collaborations: Princeton U. (USA), MIT (USA), NASA (USA), INAF (Italy), NTU (Taiwan), Harvard CfA (USA), UniBo (Italy)

References: see Gaspari et al. 2020 (Nature Astronomy) for a review. For more information, contact massimo.gaspari@unimore.it

Gauge theories describe fundamental interactions at the microscopic scale. They most efficiently apply whenever the interaction strengths are small enough, but interesting phenomena emerge from collective behavior of strongly correlated microscopic degrees of freedom, a challenge for analytical predictions of quantum effects. This project will be concerned with the interplay between strongly coupled gauge theories and their dual holographic description within the Anti de Sitter/Conformal Field Theory (AdS/CFT) correspondence. This will be achieved by considering Wilson loops, an important class of physical observables at the crossroads of the correspondence. 

Collaborations: N. Drukker (King’s College London), L. Pando-Zayas (U. of Michigan Ann Arbor), S. Penati (Milano Bicocca), D. H. Correa and G. A. Silva (Univ. Nacional de La Plata Argentina), M. Tenser (IIP Brazil). M. S. Bianchi (Univ. San Sebastian, Santiago, Chile) 

References & links: https://arxiv.org/abs/1910.00588, https://arxiv.org/abs/2305.01647, https://arxiv.org/abs/2502.15877