Resumen:

El laboratorio de Chacaltaya tiene una larga trayectoria científica. Desde su fundación en el año 1952, contribuyó fundamentalmente en el campo de la física de los rayos cósmicos en le marco de colaboraciones internacionales, con países como: Japón, Italia, Brasil, EEUU, entre otros. Actualmente, forma parte una gran colaboración internacional latinoamericana llamada LAGO, por sus siglas en inglés, donde participan los países de Argentina, Brasil, Bolivia, Colombia, Ecuador, España, Guatemala, México, Perú y Venezuela. En el próximo futuro, se espera construir un nuevo observatorio llamado ALPACA (Andes Large PArticle detector for Cosmic ray physics and Astronomy) en colaboración con el ICRR (Institute for Cosmic Ray Research) de la universidad de Tokyo, Japón. Durante la charla desglosaré con más detalle los aspectos históricos del laboratorio de Chacaltaya y finalmente daré mas detalles del nuevo proyecto ALPACA.

Resumen:

La razón mu+/mu- esta definida como la razón del número de muones con carga positiva respecto al número de muones con carga negativa que llegan a la superficie de la Tierra. Ya que la mayoría de los rayos cósmicos primarios y los núcleos con los cuales interaccionan poseen carga positiva, la producción de mesones con dicha carga es favorecida, por esta razón es de esperarse que el número de muones con carga positiva sea mayor al número de muones con carga negativa. Hasta 200 GeV/c, la cantidad mu+/mu- ha sido reportada como constante. Esta razón puede ser usada para mejorar los modelos de interacción hadrónica y entonces predecir de mejor manera el flujo de neutrinos atmosféricos. En este trabajo se presenta la medición de la razón mu+/mu- para eventos de chubascos atmosféricos con datos colectados en el 2015 por el detector ALICE-LHC. Este análisis permitió la reconstrucción de observables físicas de los muones atmosféricos tales como momento y carga en un rango de momento de 10-220 GeV/c.

Resumen:

In this work, we propose a tool to reveal the origin of the collective-like phenomena observed in proton-proton collisions. We exploit the fundamental difference between the underlying mechanisms, color reconnection (CR) and hydrodynamics, which produce radial flow patterns in Pythia8 and Epos3, respectively. Namely, the strength of the coupling between the soft and hard components which by construction is larger in Pythia8 than in Epos3. We, therefore, study the transverse momentum ($p_{T}$) distributions of charged pions, kaons and (anti)protons as a function of the event multiplicity and the transverse momentum of the leading jet ($p_{Tjet}$), being all of them determined within a pseudorapidity interval of $|\eta|<1$. Quantitative and qualitative differences between Pythia8 an Epos3 are found in the pT spectra when (for a given multiplicity class) the leading jet pT is increased. In addition, we show that for low-multiplicity events jets can produce radial flow-like behaviour.

Resumen:

We analyze the quantum supersymmetric cosmological Friedmann-Robertson- Walker model with a scalar field, with a conditional probability density and the scalar field identified as time. The Hilbert space has a spinorial structure and there is only one consistent solution, with a conserved probability density. The dynamics of the scale factor is obtained from its mean value. The uncertainty relations are fulfilled and the corresponding fluctuations are consistent with a semiclassical Universe. We give two examples which turn out to have negative potential.

Resumen:

In this talk we are going to review the current status of inflationary models from a particle physics perspective. In the last year this interaction between particle physics and cosmology has been very important and the inflationary era has been a nice topic of study. Several models are available and here we are going to present the ones called natural models, in particular we are going to put some emphasis in pNGB scenarios. Finally we are going to present some comments about the work we are doing at the department of psychology where we are applying some mathematical principles of quantum mechanics to cognitive processes.

Resumen:

We first sketch the general concepts of the lattice regularisation in quantum field theory. This formulation does not require gauge fixing, and it provides a link to statistical mechanics, which enables Monte Carlo simulations. They lead to non-perturbative numerical measurements of observables, such a the hadron spectrum, from first principle of Quantum Cromodynamics (QCD). We then summarise the status of lattice QCD with 2 plus 1 flavours of dynamical quarks, where hadronic observables can now be evaluated close to the percent level. Finally we discuss the link to Chiral Perturbation Theory and we comment on two open problems: topological freezing and the sign problem at high baryon density.

Resumen:

A desirable property of any spacetime is that the evolution of any physical field is well-defined. For sufficiently regular spacetimes this is guaranteed by global hyperbolicity. However there are physically reasonable spacetimes for which the initial value problem is well-posed but the spacetime fails to be globally hyperbolic. In this talk we will show that in certain spacetimes with hypersurface and stringlike singularities one still has local well-posedness of the wave equation in the Sobolev space $H^1$. This function space is chosen as it allows us to define the energy-momentum tensor of the field distributionally. It is also the one needed for solutions of the linearised Einstein equations. The methods we employ are therefore also relevant to finding low regularity solutions of the Einstein equations which, as shown by Dafermos, is an important issue when considering Cosmic Censorship. Motivated by this work we propose a definition of a strong gravitational singularity as an obstruction to the evolution of a test (scalar) field rather than the usual definition as an obstruction to the evolution of a test particle along a causal geodesic. This definition has the advantage that it is directly related to the physical effect of the singularity on the field (the energy-momentum tensor fails to be Integrable) and also that it may be applied to situations where the regularity of the metric falls below $C^{1,1}$ where one no longer has existence and uniqueness of geodesics. This is joint work with James Vickers

Resumen:

During the late 70s, it was proposed by G. Ruppeiner that equilibrium thermodynamics in the context of thermodynamic fluctuation theory can be studied using tools of Riemannian geometry. Inspired by the role that curvature plays in General Relativity, he proposed that this mathematical object may also yield valuable physical information regarding microscopic interactions and critical phenomena, without relying on the statistical-mechanical model of a system. Though lacking a rigorous proof, this claim has been successfully tested in sundry particular cases, and has been recently implemented in black hole thermodynamics with the aim of retrieving information about the nature of microscopic interactions underlying macroscopic equations of state. In this talk, I will briefly introduce Ruppeiner's formalism from a geometric viewpoint. I will show that, in order to make it fit into black hole thermodynamics, it has to be modified, and I will suggest a possible direction thereto.

Resumen:

La invariancia local de Lorentz (ILL) es uno de los principios fundamentales de la relatividad general, y como tal debe ser probado experimentalmente. Además, varios esquemas de gravedad cuántica han propuesto que estructuras no-triviales del espacio-tiempo podrían generar violaciones a dicho principio. Por otra parte, la teoría de campos efectiva es una herramienta robusta para describir sistemas físicos cuando los grados de libertad fundamentales se desconocen y, en nuestro caso, ayuda a generar una parametrización que incluye violaciones a la ILL. Dicha parametrización es una guía para la búsqueda experimental de tales violaciones, pero también permite hacer pruebas de consistencia a nivel teórico. En particular, voy a discutir la compatibilidad de violaciones a ILL con la invariancia ante difeomorfismos, la posibilidad de tomar un punto de vista tipo Palatini, la construcción de un término de frontera tipo Gibbons-Hawking y el problema de Cauchy. Con estos estudios se han revelado algunas tensiones que podrían eventualmente descartar la posibilidad de extender la física establecida con violaciones a la ILL.