In this new paper (**arXiv:1805.07099**) we study the Lie bialgebra structures that can be built on the one-dimensional central extension of the Poincaré and (A)dS algebras in (1+1) dimensions. These central extensions admit more than one interpretation, but the simplest one is that they describe the symmetries of (the noncommutative deformation of) an Abelian gauge theory, U(1) or SO(2) on the (1+1) dimensional Minkowski or (A)dS spacetime. We show that this highlights the possibility that the algebra of functions on the gauge bundle becomes noncommutative. This is a new way in which the Coleman-Mandula theorem could be circumvented by noncommutative structures, and it is related to a mixing of spacetime and gauge symmetry generators when they act on tensor-product states. We obtain all Lie bialgebra structures on centrally-extended Poincaré and (A)dS which are coisotropic w.r.t. the Lorentz algebra, and therefore all of them admit the construction of a noncommutative principal gauge bundle on a quantum homogeneous Minkowski spacetime. It is shown that several different types of hybrid noncommutativity between the spacetime and gauge coordinates are allowed by introducing quantum extended Poincaré symmetries. In one of these cases, an alternative interpretation of the central extension leads to a new description of the well-known canonical noncommutative spacetime as the quantum homogeneous space of a quantum Poincaré algebra of symmetries.

# Author: angballesteros

# New Master Program in Mathematical Physics

A new Master Degree in Physics will be offered by the University of Valladolid starting on september 2018. This Program includes a Master Program in Mathematical Physics in which several courses will be taught by members of our research group. Pre-registration on the Master is already open, and full information can be found **here**.

# A unified approach to Poisson-Hopf deformations of Lie-Hamilton systems based on sl(2)

Based on a recently developed procedure to construct Poisson-Hopf deformations of Lie-Hamilton systems, a novel unified approach to nonequivalent deformations of Lie-Hamilton systems on the real plane with a Vessiot-Guldberg Lie algebra isomorphic to 𝔰𝔩(2) is proposed in the paper **arXiv:1803.07404**. This, in particular, allows us to define a notion of Poisson-Hopf systems in dependence of a parameterized family of Poisson algebra representations. Such an approach is explicitly illustrated by applying it to the three non-diffeomorphic classes of 𝔰𝔩(2) Lie-Hamilton systems. Our results cover deformations of the Ermakov system, Milne-Pinney, Kummer-Schwarz and several Riccati equations as well as of the harmonic oscillator (all of them with t-dependent coefficients). Furthermore t-independent constants of motion are given as well. Our methods can be employed to generate other Lie-Hamilton systems and their deformations for other Vessiot-Guldberg Lie algebras and their deformations.

# Seminar “On symmetry techniques for differential equations”

Speaker:** María Luz Gandarias (Universidad de Cádiz)**

Date and time: December 12, 17:00

Place: Seminario del Departamento de Física, Facultad de Ciencias

# Seminar “Quantum field theory on kappa-Minkowski spacetime”

Speaker:** Flavio Mercati (La Sapienza, Rome)**

Date and time: November 29, 17:00

Place: Seminario del Departamento de Física, Facultad de Ciencias

# Curved momentum spaces from quantum (Anti-)de Sitter groups in (3+1) dimensions

In this new paper (**arXiv:1711.05050**), curved momentum spaces associated to the κ-deformation of the (3+1) de Sitter and Anti-de Sitter algebras are constructed as orbits of suitable actions of the dual Poisson-Lie group associated to the κ-deformation with non-vanishing cosmological constant. The κ-de Sitter and κ-Anti-de Sitter curved momentum spaces are separately analysed, and they turn out to be, respectively, half of the (6+1)-dimensional de Sitter space and half of a space with SO(4,4) invariance. Such spaces are made of the momenta associated to spacetime translations and the “hyperbolic” momenta associated to boost transformations. The known κ-Poincaré curved momentum space is smoothly recovered as the vanishing cosmological constant limit from both of the constructions.

# Seminar “From Poisson geometry to non-commutative spacetime”

Speaker:** Iván Gutiérrez-Sagredo (University of Burgos)**

Date and time: October 23, 14:15

Place: Mathematics Department, FAU Erlangen-Nürnberg