Triangle Seminars

Abstract:
The talk will begin with a brief review of Quantum Chromodynamics (QCD) and the Confinement problem. Lattice Gauge Theory (LGT) provides a non-perturbative formulation of QCD, which has led to good numerical results for the low-lying hadron spectra. Yet, an analytical understanding of QCD is not available. I will then discuss several gauge theories which have some of the key features of QCD. One of them is based on the gauge/gravity duality and is described by the warped deformed conifold background of type IIB string theory. This theory exhibits confinement, and the quark-antiquark potential is similar to that found in LGT.

The 1+1 dimensional gauge theories have also served as useful models of quark confinement. I will revisit the classic Schwinger model and its lattice Hamiltonian formulation. A mass shift between the lattice and continuum definitions of mass, which is motivated by chiral symmetry, is shown to lead to improved results. I will also present the zero-temperature phase diagram of the two-flavor Schwinger model at theta=pi, which exhibits dimensional transmutation and spontaneous breaking of charge conjugation. Finally, I will discuss the 2D SU(N) gauge theory coupled to an adjoint multiplet of Majorana fermions. This model has a rich topological structure. I will introduce a Hamiltonian lattice approach to this gauge theory, in which one can compute the spectrum, the string tension, and other observables. The talk will end with some surprising exact results for this model.

Abstract:
Quantum computers have the potential to revolutionize both quantum simulations and classical computations. Rapid advancements in quantum hardware has not only introduced new opportunities but also posed significant theoretical challenges in understanding quantum dynamics. These developments highlight the need for benchmarking models—interacting many-body systems that can be solved exactly or numerically to assess the capabilities of quantum processors. In this talk, I will discuss powerful theoretical tools to address these challenges, focusing on the Sachdev–Ye–Kitaev (SYK) model and the emerging framework of entanglement in time, an information-theoretic approach designed to probe dynamical properties of quantum systems.

Abstract:
The interior of asymptotically AdS black holes provides a setting where one can naturally extend the notion of holographic RG flows past their conventional infrared fixed points. In this talk, I will describe how these extended “trans-IR” flows provide a unique framework for capturing gravitational dynamics behind the horizon, especially as one approaches a spacelike singularity. Near the singularity, the geometry enters a regime governed by the BKL conjecture and characterized by a sequence of Kasner epochs and eras. To get a handle on the degrees of freedom involved in this evolution, I will introduce a monotonic function, known as the thermal a-function, which tracks the flow into the trans-IR region. With this function, I will show that the full sequence of Kasner epochs and eras can be effectively captured, and the degrees of freedom thin out and ultimately vanish at the trans-IR fixed point.

Abstract:
In this talk, I will review the arbitrary-spin theory introduced in 2005.03071 to model spinning black holes in the post-Minkowskian approximation, and describe a procedure to systematically obtain Compton-like amplitudes in it, exploiting their factorization properties, and colour-kinematics duality. I will furthermore comment on the constraining of Wilson coefficients for arbitrary spinning bodies and its relation to colour-kinematic duality. This talk is based on 2503.22597.

Abstract:
Gravity is derived from an action given by the geometrical quantum relative entropy coupling matter fields with geometry. The fundamental idea is to relate the metric of Lorentzian spacetime to a quantum operator, playing the role of an renormalizable effective density matrix and to describe the matter fields topologically, according to a Dirac-Kähler formalism, as the direct sum of a 0-form, a 1-form and a 2-form. While the geometry of spacetime is defined by its metric, the matter fields can be used to define an alternative metric, the metric induced by the matter fields, which geometrically describes the interplay between spacetime and matter. The proposed entropic action is the geometric quantum relative entropy between the metric of spacetime and the metric induced by the matter fields. The modified Einstein equations obtained from this action reduce to the Einstein equations with zero cosmological constant in the regime of low coupling. By introducing the G-field, which acts as a set of Lagrangian multipliers, the proposed entropic action reduces to a dressed Einstein-Hilbert action with an emergent small and positive cosmological constant only dependent on the G-field. The obtained equations of modified gravity remain second order in the metric and in the G-field. A canonical quantization of this field theory could bring new insights into quantum gravity while further research might clarify the role that the G-field could have for dark matter.

We furthermore show that the geometrical quantum relative entropy associated to the Schwarzschild metric, which provides an approximate solution of the modified gravity equations, follows the area law for large Schwarzschild radius.



Bianconi, G., 2025. Gravity from entropy. Physical Review D, 111(6), p.066001.

Bianconi, G., 2025. The quantum relative entropy of the Schwarzschild black hole and the area law. Entropy, 27(3), p.266.