El Coloquio de Física y Matemáticas se lleva a cabo los jueves a las 12:00 pm, en el Auditorio de la Facultad de Ciencias.
29 de noviembre
On decompositions of categories in homological mirror symmetry
Kansas State University
Abstract: Mirror symmetry proposes a deep relationship between two different geometric subjects, algebraic geometry and symplectic geometry. Many classical questions concerning invariants in one setting can be understood from the other, and vice versa. The categorical version of this relationship is a derived category equivalence proposed by Maxim Kontsevich. In this talk, I will discuss a general strategy towards proving this conjectural equivalence based on decomposing categories. On the algebraic side, the decomposition will be a consequence of birational geometry or variation of quotients. On the symplectic side, there will be a mirror decomposition through degeneration of a symplectic fibration. I will discuss the current advances on both sides and some speculations on their connections to other areas of mathematics.
15 de noviembre
The Poincaré-Birkhoff Theorem
The University of Mississippi
Abstract: In 1912, the year of his death, Poincaré made a conjecture in the context of the restricted 3-body problem in celestial mechanics, and Birkhoff then proved it the following year. Their theorem concerns the number of fixed points of an area preserving map of the annulus to itself. The annulus is the region of the plane between two concentric circles. By considering a rotation of the plane, it is clear that such a map may have no fixed points at all. However, under the condition that the map must rotate the two boundary circles in opposite directions, such a map must have at least two fixed points. In retrospect, this is perhaps the first theorem of symplectic topology. I will present some of the context of the theorem, and will sketch a proof of a special case that illustrates some of the connections to modern topics in symplectic topology.
8 de noviembre
Scrutinizing Higgs Boson Scattering Cross Section Predictions with Precision
Wichita State University
Abstract: The Large Hadron Collider (LHC) experiment is a tool for discovering new particles. In the 2012 a new boson was discovered with mass of about 125 GeV and in 2013 it was revealed by experimentalists analyzing data that the new particle behaved much like the Higgs boson of the Standard Model. In 2013 both Francois Englert and Peter W. Higgs were awarded the Nobel Prize in Physics. In this talk, I will discuss the mechanism which provides masses to fermions and gauge bosons, i.e., the Higgs mechanism. I will discuss how experimentalists probe the properties of the Higgs boson using the LHC experiment and the importance of Monte Carlo simulation tools. I will present the methodology and technical details involved in computing scattering cross sections at the LHC. I will close my talk by presenting results for the production cross section of a Higgs boson via electroweak gauge couplings at the LHC.
Exploring Connections between Dark Matter and Flavor
University of Texas at Austin
Abstract: The Standard Model of particle physics has been extremely successful in describing the world at the shortest distance scales that we have probed experimentally. However, there are many puzzles that the Standard Model does not address, and that point us to the existence of new particles and interactions. For example, the existence of dark matter, the asymmetry between matter and antimatter in the universe, the existence of heavier copies of matter particles (the flavor puzzle), and an apparent fine tuning in the mass of the Higgs boson all indicate Beyond the Standard Model physics. When theorists speculate about what such new physics may look like, it is important to look for connections between these open questions. For instance, the most well-researched models of dark matter also have a connection to either the Higgs fine tuning puzzle, or to the matter-antimatter asymmetry puzzle. In this talk I will describe work that I and my collaborators have done over the past few years on exploring a different possible connection, between dark matter and the flavor puzzle. I will describe what kinds of new possibilities open up when exploring such a connection, and how such a scenario might manifest itself in terms of its experimental and astrophysical signatures.
18 de octubre
Precision tests of the Standard Model and beyond
University of Pittsburgh
Abstract: Throughout the history of physics, there are many examples of important discoveries being triggered by finding small deviations in seemingly well-understood systems. Within the Standard Model of particles physics, the precision analysis of properties of W- and Z-bosons thus led to predictions for the masses of the top quark and Higgs boson prior to their direct observation. After the discovery of the Higgs boson in 2012, the Standard Model is complete, but precision tests now offer a window into new physics at much higher energy scales. This talk will give an overview of the most relevant observables and describe the challenges in theoretically calculating predictions for them to the required accuracy. A number of examples will be given to demonstrate how the comparison of these predictions with experimental results allows us to constrain models beyond the Standard Model. In a few cases, an observed discrepancy between measurement and theory prediction may be also turn out to be a first hint of new physics.
11 de octubre
Descifrando el reconocimiento del cáncer por parte del sistema inmune
Memorial Sloan Kettering Cancer Center
Resumen: El cáncer es un proceso evolutivo, y la principal razón de su triunfo es la habilidad de evadir al sistema inmune. El Premio Nobel de Medicina 2018 ha sido otorgado a James P. Allison y Tasuku Honjo por demostrar, a partir de la inhibición de la regulación del sistema inmune, que la inmunoterapia tiene la capacidad de restaurar el reconocimiento del cáncer. Su trabajo ha revolucionado el tratamiento contra el cáncer de pulmón o el melanoma en fase metastásica, cambiando de manera fundamental la forma de combatir ese mal. Desafortunadamente solo alrededor del 30% de los pacientes responde a esta terapia. En este coloquio, voy discutir las bases genéticas que hemos descubierto recientemente que influyen en una respuesta exitosa a este tipo de inmunoterapia.
27 de septiembre
Random Walk Models and Applied Chemical Ecology, or how big is a lattice point?
Michigan State University
Abstract: A wide variety of random walks satisfy Donsker’s invariance principle, which states that over large time and space scales they scale to Brownian motion in distribution. Suppose we wish to compute the probability for a random walk to hit a particular set T within a given time. In light of the invariance principle, it is natural to approximate this hitting probability by the probability for Brownian motion to hit some set T’ over the same time. But which set T’ should we use? For walks in two dimensions this is a subtle problem because the probability for Brownian motion to eventually hit any disk is one, regardless of the radius.
Hitting probabilities play a key role in a theory of insect trapping developed in recent years using a combination of random walk models and field experiments. The goal of this theory, which is still under development, is to provide a sound scientific framework for farmers and pest managers to make decisions about when to apply chemical pesticides based on numbers of pests captured in monitoring traps.
In this talk I will briefly describe the scientific background briefly and then turn to the mathematical story of the associated random walk models. I will present strong numerical evidence for a conjectured “renormalization” of trap radii that is needed for the invariance principle analysis for these random walks. Finally, I will present recent work, borrowing ideas from spectral theory and the physics of renormalization, which provides an exact analysis of certain lattice models to compute “effective Brownian radius” for a lattice point, which can be used to obtain the best approximation of random walk hitting probabilities. I will close the talk with some conjectures about the numerical error in this approximation.
This talk is based on joint work with A. Becerra, T. Weicht (undergraduate students), Z. Tilocco (graduate student), and J. Miller and C. Adams (MSU Entomology)
20 de septiembre
The XYZ Affair: Tales of the Third (and Fourth) Hadrons
Arizona State University
Abstract: In the past 15 years, many new particles have been discovered that are clearly hadrons (interacting via the strong nuclear force), but do not seem to fit into either of the known hadron categories of meson (quark-antiquark) or baryon (3 quarks). Several species of these “exotic” particles, called X, Y, and Z, are now believed to be tetraquarks, and in July, 2015 the LHC announced the discovery of pentaquark states, Pc. We begin by reviewing the basics of QCD (quarks, color, confinement, etc.), and then turn to the question of how conventional mesons are identified, which allows one to distinguish exotics. After reviewing their experimental discovery, we consider the question of how exotics are assembled. Several competing physical pictures attempt to describe the structure of exotics: as molecules of known hadrons, as the result of kinematical effects, and others. I propose that they arise due to the formation of compact diquarks, a well-known but under-appreciated phenomenon of QCD. The competing facts of kinematics and diquark confinement create an entirely new kind of bound state: not a molecule with well-defined orbits, but an extended object that lasts only as long as it takes for quantum mechanics to allow the separated quarks and antiquarks to “find” one another, and allow decays to occur. I will discuss several observed effects that support this picture.
30 de agosto
Rigorous Applicable Quantum Field Theory
Centro de Ciencias Matemáticas – UNAM
Abstract: One relative easy and quite rigorous path to quantize a field theory on an arbitrary curved spacetime is given by geometric quantization. In principle one uses the wave equation to construct a phase space (+symplectic structure) and a corresponding complex structure. Once we have this structure a simple formula gives us an inner product that allows the construction of a Hilbert space and thus (by taking the infinite symmetric tensor product) a Fock space. In this talk we explicitly and rigorously construct complex structures for explicit examples.
16 de agosto
String Theory and the Quantum Universe
University of Wisconsin-Madison
Abstract: Physics thrives on crisis. Resolving the conflicts between existing paradigms often bring new insights that transform our understanding of the laws of Nature. I will explain why the current paradigms of fundamental physics – quantum mechanics which governs the physics of the very small, and relativity which governs the physics of the very large – are in conflict with each other. These conflicts arise in physical situations such as the physics of black holes and the beginning of the universe. String theory is currently the most developed framework in reconciling quantum physics with gravity. I will discuss how string theory drastically changes our views of space, time, and matter. I will also illustrate how string theoretical ideas can be tested through particle physics experiments and cosmological observations.
2 de agosto
The Mysterious Dark Matter and Dark Energy in our Cosmos
California State University, Fresno
Abstract: Based on observation there is a consensus that two of the major components of the Cosmos are “dark” — they do not interact with ordinary matter to any large degree and are known only through their gravitational effects. The understanding of these two mysterious components, dubbed dark matter and dark energy, is one of the major goals of fundamental physics. In this talk I present some basic properties of these two dark components and give some of the history behind their discovery.
15 de junio, 3:00 pm
The Higgs Boson and New Physics at the Large Hadron Collider
University of Kansas
Abstract: The Large Hadron Collider (LHC) presents us with a unique opportunity to explore the fundamental theory of nature. The first run of the LHC was very successful, culminating in the discovery of a Higgs boson. With the LHC now running at a higher energy more discoveries are highly anticipated. In this talk, I will review the importance of the Higgs discovery and its relationship to additional new physics. In particular, I will focus on how precise measurements of Higgs boson processes can shed light on the building blocks of our universe.
Plática (PDF): IL_Colima_2018
7 de junio
Victoria Cantoral Farfán
3 de mayo
De la geometría riemanniana al análisis geométrico
Resumen: A finales del siglo XX y principios del XXI surgió la noción de variedad. Apareció entonces la geometría diferencial y, en particular, la geometría riemanniana. En sus aproximadamente cien años ha dado muchos resultados; entre ellos, conjeturas famosas que han podido ser demostradas. La herramienta que la geometría riemanniana empezó ha usar cada vez más fue el análisis. Así nació el análisis geométrico. El propósito de esta platica es mostrar ejemplos de estos sucesos historico-matemáticos, incluyendo parte de mi investigación.
19 de abril
Resolving the Mysteries of the Universe with Neutrinos and Mineral Oil
Abstract: From the very beginning of its proposal back in 1930 by Wolfgang Pauli, a neutrino has been an elusive particle. Nonetheless, it has been found to be the key to a better understanding of not only the Sun, but perhaps even the origin of matter in the Universe.
The organic liquid scintillator technology has been successfully used in the past for neutrino searches where sensitivity to low energies, as well as real-time and energy information, are required. The most prominent examples of this application are utilized in the studies of solar neutrinos, as well as geological and reactor anti-neutrinos around the world. In many cases, the signal from these rare events can be enhanced by mixing in various isotopes that can act as an additional target for neutrino interactions in the active liquid of the detector. When this target is selected to become a source of the signal itself, it can open up an entirely new area of physics to investigate.
In this presentation, I will introduce the history of neutrinos and then focus on the application of metal loaded liquid scintillator technology along with the impact of the SNO+ project on the field of rare neutrino interactions.
12 de abril
Neutrinos de Dirac con sabor
Technische Universität München
Resumen: En esta charla mencionaremos algunos de los problemas abiertos en física de neutrinos, como el problema de sabor. En particular hablaremos de la posibilidad de que los neutrinos no sean su misma antipartícula y de las consecuencias fenomenológicas.
15 de marzo
Crecer o no crecer: comportamiento termomagnético de αs
Resumen: Las propiedades de la materia fuertemente interactuante a temperatura finita y en un medio magnetizado han sido objeto de interés reciente, principalmente debido al descubrimiento del fenómeno conocido como “catálisis magnética inversa”. Este fenómeno consiste en el decrecimiento de la temperatura de transición quiral y del incremento en la intensidad del condensado de quarks como función de la intensidad del campo magnético. En esta charla haré un resumen de resultados recientes que parecen indicar que tal efecto se debe a las propiedades de la constante fuerte cuando se considera su dependencia térmica y magnética.
18 de febrero
Lentes magnéticas para dirigir partículas
Natalia Tene, Brenda Gómez y Diego Radillo
Estudiantes de la Licenciatura en Física
Facultad de Ciencias
Resumen: Un equipo de investigación está trabajando en un prototipo de propulsor de iones de xenón y se encuentran con el problema de que los iones salen de éste con un rango amplio de ángulos. Nosotros extendemos la propuesta de utilizar un campo magnético para dirigir las velocidades de los iones a una dirección más uniforme antes de salir del propulsor. Para conseguir esto diseñamos un dispositivo que alinea las trayectorias de los iones por medio de aplicar los principios de las lentes magnéticas.
8 de febrero
Nuclear matter under extreme conditions: the MExNICA initiative
Maria Elena Tejeda Yeomans
Facultad de Ciencias
Abstract: We are made of nuclear matter under “ordinary” conditions and we are surrounded by stars that are made of nuclear matter under “extreme” conditions. In this case “ordinary” and “extreme” refer to the different conditions of density, temperature and other external agents, under which the extraordinary behaviour of nuclear matter can be studied. Recent experiments allow for the study of quarks and gluons in the nucleons under these conditions, and amazingly enough, with these experiments we can also learn about the conditions that prevailed when the Universe was very young. In this talk I will start by telling you about the studies of nuclear matter under extreme conditions for different physical systems, focusing on the new theoretical tools that have been developed to characterize the quark-gluon plasma and presenting the phenomenological landscape in the phase diagram of nuclear matter. Next, I will present some of the challenges and opportunities to study nuclear matter under extreme conditions using the Multi-Purpose Detector (MPD) at the Nuclotron-based Ion Collider fAcility (NICA) which is located at the Joint Institute for Nuclear Research (JINR), in Dubna, Rusia. Finally, I will summarize the theoretical and experimental advances and plans made by the MExNICA collaboration in this area.