We formulate Positivity Bounds for scattering amplitudes including exchange of gravitons in four dimensions. We generalize the standard construction through dispersion relations to include the presence of a branch cut along the real axis in the complex plane for the Maldestam variable s. In general, validity of these bounds require the cancellation of divergences in the forward limit of the...
In this talk, after reviewing the concept of quantum breaking, and its relation to scrambling, concepts which proved fundamental for our understanding of composite systems such as condensates, black holes and De Sitter, I will show how to study them within the context of 2PI effective action. To do so I will focus on a simple model of a one dimensional condensate in which a logarithmic...
We explore the ability of future cosmological surveys to put constraints on string theory, through the Swampland program. String theory is sometimes thought to be unfalsifiable due to the incredibly large amount of low energy effective versions that can be derived in its framework. However, it is well known that constructing consistent solutions in a de-Sitter background is tremendously...
Hawking's calculation of particle production by a black hole is based on the semi-classical approximation, in which back-reaction on the metric is not taken into account. This leaves open the question of how the black hole evolves as a result of evaporation. In an attempt to answer it, we construct a simple analogue system, which shares the information storage properties of a black hole such...
We find numerically static vortex solutions where the scalar and gauge fields have a non-singular profile under Einstein gravity in an AdS$_3$ background. Vortices with different winding numbers $n$, VEV $v$ and cosmological constant $\Lambda$ are obtained. These vortices have positive mass and are not BTZ black holes as they have no event horizon. The mass is determined in two ways: by...
The problematic huge hierarchy between the usual 4-dimensional Planck mass scale of gravity and the ElectroWeak symmetry breaking scale can interestingly disappear at some point-like location along extra space-like dimensions where the effective gravity scale is reduced down to the TeV scale. Field theories with point-like particle locations (3-dimensional brane-worlds) or point-like...
A crucial challenge in perturbative Quantum Field Theory is the description of quantum fluctuations at high-energy scattering processes by the calculation of multi-loop scattering amplitudes. Aiming for improving the efficiency of these computations, we delve into a new technique based on the Loop-Tree Duality (LTD). We analyse the multiloop topologies that appear for the first time at four...
Since the rise of the AdS/CFT duality, integrability has proven to be an important tool to advance our understanding of massless QFT. In this talk we demonstrate that integrability is also present in massive QFT in D>2 spacetime dimensions. We show that large classes of massive Feynman integrals are highly constrained by an infinite dimensional Yangian symmetry. When translated to momentum...
We define a generalized entanglement measure in the context of AdS$_3$/CFT$_2$. Compared to the ordinary entanglement entropy between spatial degrees of freedom dual to the area of the Ryu-Takayanagi surface, we take into account both entanglement between spatial degrees of freedom as well as between different fields of the boundary CFT. We then calculate this generalized entanglement measure...
Non-Hermitian quantum theories have been applied in many other areas of physics. In this talk, I will review recent developments in the formulation of non-Hermitian quantum field theories, highlighting features that are unique compared to Hermitian theories. I will describe their crucial discrete symmetries and how continuous symmetry properties are borne out, including Noether's theorem...
The search for renormalization group invariant relations among parameters to all orders in perturbation theory constitutes the basis of the reduction of couplings concept. Reduction of couplings can be achieved in certain N=1 supersymmetric grand unified theories and few of them can even become finite at all loops. The resulting theories in which successful reduction of couplings has been...
While CP violation has never been observed in the strong interactions, the QCD Lagrangian admits a CP-odd topological interaction proportional to the so called theta angle, which weighs the contributions to the partition function from different topological sectors. The observational bounds are usually interpreted as demanding a severe tuning of theta against the phases of the quark masses,...
The AdS/CFT correspondence allows to describe strongly-coupled quantum field theories in terms of weakly-coupled gravitational systems, offering an opportunity to investigate quantum systems at strong coupling far from thermal equilibrium. A simple non-equilibrium process is the quench, representing a system thermalization after the sudden injection of energy. In the case of localized...
We investigated the appearance of straight infinite Wilson lines lying on the self-dual plane in the context of the Self Dual sector of the Yang Mills theory and in connection to the Lagrangian implementing the MHV vertices (MHV Lagrangian) according to the Cachazo-SvrcekWitten (CSW) method. The plus helicity field in the MHV Lagrangian was already known to be a straight infinite Wilson line...
Computations of the trace anomaly of chiral fermions have raised a discussion regarding possible unitarity issues at one-loop in four-dimensional theories involving chiral fermions. This was manifested by the claimed existence of an imaginary CP-violating term in the trace of the energy momentum tensor – the Pontryagin density. We revisit this computation using dimensional regularization and...
The data collected at the LHC does not indicate significant deviations from the predictions of the Standard Model (SM). Taking into account that precision observables can be predicted already at two and three loops, it is evident the necessity to develop stringent tests of self-consistency of the SM. We compute the two-loop $\beta$-function of pure Yang-Mills and quantum chromodynamics using...
Time is an enigmatic property of the universe which confounded physicists for ages. This property is increasingly dark and cryptic when we deal with metric spaces of the microscopic scales in the universe. There are remarkable theories, in particular, the loop quantum gravity (LQT) which helps us in understanding the cosmology of these microscopic scales. However, the theory possesses...
Dynamical symmetry breaking can happen through a Higgs mechanism but also spontaneously within a strongly-enough coupled theory.
We treat a field-theoretical quark model of QCD based on a linear+Coulomb Cornell potential (to account for the longitudinal interaction), together with a transverse interaction (to account for Coulomb gauge gluons) in BCS approximation.
After extracting the...
