One of the areas of greatest theoretical development in contemporary physics corresponds to gravitation, in which, matter and geometry, bind to describe with amazing precision the dance of the bodies in the universe. This group does research on tests of gravitation, finite distributions of matter and motion of particles in different spacetime, with special emphasis on contrasting the parameters of the theory with the current observational data.

**Investigators**:

Professors: Víctor Cárdenas - José Villanueva - Alfredo Vega - Osvaldo Herrera

Students: Constanza Osses (undergraduate student)

The aim of Particle Physics is to describe natural phenomena taking into account the fundamental constituents of matter and its interactions. To date we know that matter is made up of quarks (that for example exist inside protons and neutrons) and by leptons (like the electron). Said particles, by their varied interactions, form different structures present in our Universe. For other side, according with our actual knowledge, the fundamental interactions responsable of all physical phenomena are four: gravity, electromagnetism, weak and strong interactions.

In our Institute, research on Particle Physics is focused in two big topics. For one side we work on development of mathematical techniques to evaluate Feynman diagrams at high order, that are usual tools in any perturbative calculation used to study processes that involve subatomic particles. And for other side our group works in hadronic physics in the non perturbative region using different phenomenological methods, specially those based on Gauge / Gravity dualities in Bottom - Up approach and using Light Front Holography.

**Investigators**:

Professors: Alfredo Vega - Iván González - Quintín Molina

The theoretical physics group of the Instituto de Física y Astronomía at the Universidad de Valparaíso does research in several areas, ranging from the very small - as in the study of elementary particles - to the largest scales imagined – as is given in the study of theories of gravitation and cosmology. These complement each other, since its members work on converging themes, besides being related to astrophysics. In our institute various topics are discussed in the following areas:

Cosmology is a rapidly developing area linking aspects of theories of *gravitation, particle physics and astrophysics*. The discovery of the accelerating universe expansion and the successful detection of anisotropy and polarisation in the cosmic background radiation implies a universe where almost 96% of its content is unknown in nature. We know that most of the dark matter is non baryonic, and that dark energy fills the universe to the largest observed scales. In this group we study topics in theoretical cosmology, both at early times (inflation, reheating) and at later epochs (dark matter and dark energy dominated eras). We also study the constraints on alternative cosmological models, using specially, information from galaxy clusters as observational probes, such as, gravitational lensing, X-ray emision, Sunyaev-Zeldovich effect, etc. Victor Cardenas and Jose Villanueva develop theoretical models for dark matter and dark energy, testing them against a diverse set of observational data, to help us to better understand the features of these dark components.

**Investigators:**

Professors: José Villanueva - Víctor Cárdenas - Osvaldo Herrera

Students: Constanza Osses (undergraduate student)