Theory: SM basic concepts part I

• Gustavo Ardila (Universidad de los Andes)

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Statistical techniques in data analysis: curve fitting, p-values, bin-bin likelihood, exclusion limits setting, part I

• Carlos Andrés Florez Bustos (Universidad de los Andes)

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Physics objects reconstruction in the LHC experiments

• Carlos Avila (Universidad de los Andes)

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Theory: SM basic concepts part II

• Gustavo Ardila (Universidad de los Andes)

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A brief intro to MG, MADAnalysis, Pythia, Delphes

• Jose Ruiz (Universidad de Antioquia)

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Seesaw type II Mechanism for Dirac neutrinos

• Kimy Agudelo Jaramillo (Universidad de Antioquia)

Room: --- In this work, we show a study of the generation of neutrino masses is carried out from the seesaw type II Mechanism for Dirac neutrinos. These mechanisms not only explain the mass of the neutrino but also its small value compared to charged quarks and leptons. Therefore, a model is proposed to obtain the small neutrino masses by extending the visible content of the Standard Model (SM) with $S$ and two right-handed singlet neutrinos $ (\nu_ {R_1}, \nu_ {R_2}) $. These right-handed neutrinos are charged under a new symmetry $U (1)_X$ . In addition, it is necessary to add a heavy scalar doublet to play the role of messenger between the visible sector (SM) and the hidden sector. hidden sector. Extending the SM with a new abelian symmetry automatically violates the invariant of Lorentz, therefore the following conditions must \begin{equation} \label{eq:triplet} \sum_{\alpha=1}^{N'} n_{\alpha} + 3m =0 \,, \end{equation} % \begin{equation} \label{eq:triplet1} \sum_{\alpha=1}^{N'} n'^{3}_{\alpha} +3m^{3} = 0\,, \end{equation} where, $ n_\alpha $ is defined as the charge of the chiral fermions under the new symmetry and $ 3m $ the sum of the charges of the SM and $m \equiv e + 2L$. If the SM is extended with an additional dark $U(1)_D$ gauge symmetry (under which it is uncharged), and $N$ right-handed chiral fields singlets under the SM group, the $U(1)_D$ is not anomalous if the Diophantine equations are fulfilled \begin{align} \label{eq:triplet2} \sum_{\alpha=1}^{N} n_{\alpha} =&0\,, & \sum_{\alpha=1}^{N} n'^{3}_{\alpha} =& 0\,. \end{align}

Representations of graded Lie Algebras

• Juan Camilo Guzman Martinez (Universidad Nacional)

Room: --- The Lie algebra of the Poincare group is constructed to extend it to graded Lie algebras by adding fermionic generators. Minimal irreducible representations of these algebras and their respective superfields will be studied to construct invariant Lagrangian densities under graded algebras.

SU(4) weak singlet leptoquark in $R_K$ flavor anomaly

• Oscar David Rosero Cárdenas (Universidad de Nariño)

Room: --- We present a detailed study of a proposed model to explain the experimental hints of new physics in B meson decays within the frameork of the Pati-Salam unification. The model is based on the local gauge group SU(4)L⊗SU(4)R⊗SU(2)L⊗U(1)′ and part of its gauge bosons are (3,1)2/3 vector leptoquarks. The key feature of the model is that SU(4)R is broken at a high energy scale, which suppresses right-handed lepton flavor changing currents at the low energy scale. The constraints imposed on the model by independent measurements show that the mass of the leptoquark can be as low as 10 TeV, not requiring the introduction of quarks or leptons mixings with new vector-like fermions. We obtain constraints from various pseudo-observables for the leptoquark couplings and contrast them against a model-independent analysis.

Measurement of the $B^{+}$ differential cross section as a function of transverse momentum and multiplicity density in pPb collisions at $\sqrt{s_{NN}}=8.16$ TeV

• Camilo José Torres Castaño (Universidad de Antioquia)

Room: --- We present the first observation of the $B^{+}$ meson production suppression in high-multiplicity respect to low multiplicity pPb collisions at $\sqrt{s_{NN}} = 8.16$ TeV with data collected by the CMS detector during 2016 and corresponding to an integrated luminosity of 175 nb$^{-1}$. The measurement uses exclusive decay channel $B^{+}\rightarrow J/\psi \ K^{+}$. The inclusive results show a good agreement with theoretical calculations from the FONLL within uncertainties. The cross section ratio measurements scaled by the charged-particle multiplicity density, from low to high multiplicity, shows a significant decrease on the $p_{T}$ dependence with increasing charged-particle multiplicity density. Results may indicate interplays of beauty quark energy loss, diffusion effects models in high multiplicity events, and gluon saturation models in lower multiplicity events.

Ecuación de Schwinger-Dyson para un propagador de fermiones completamente vestido

• Ruben Hernando Criollo Estrella (Universidad de Nariño)

Room: --- The Schwinger-Dyson equations (DSE) were obtained from a functional generation of masses M(p) for a fermion propagator, which are analogous to the Euler-Lagrange equations in quantum field theory (QFT), because these correspond to the equations of motion of Green's functions. The DSE's solve them by means of a truncation scheme. In order to solve abelian models for quantum chromodynamics (QCD) at low energies, which allow us to obtain the mass spectrum for pseudoscalar mesons (Jp=0−) and the decay constants.

Feasibility studies for searches enhanced by machine learning methods of leptoquarks with preferencial couplings to third generation fermions at the LHC

• Cristian Fernando Rodriguez Cruz (Universidad de los Andes)

Room: --- In recent years, the observations reported by LHCb, Babar, and Belle experiments of the apparent anomalies in B-meson decays, together with the possible anomaly on the magnetic angular momentum of muons reported by the Muon $g-2$ experiment at Fermilab, indicate that, perhaps, lepton flavour universality is violated in the SM, in turn being a window to search new physics. Of the new models that intent to extend the SM to explain violation of lepton flavour universality, several of them introduce new particles with preferential couplings to third generation fermions. Some of the most popular models include the hypothetical production of heavy mass particles in particular we concéntrate on Leptoquarks (LQ). In this project, we seek to conduct feasibility studies for the LHC associated with the production of these new hypothetical particles through different production mechanism and with preferential couplings to third generation fermions. These studies are conducted using different simulation packages to emulate the LHC conditions and the statistical analysis will use Machine Learning (ML) methods.

Probing new physics at the LHC with $\mathrm{b}\tau\nu$ final states

• Tomas Atehortua (Universidad de Antioquia)

Room: --- The $R_{D^{(\ast)}}$ anomaly is one of the most intriguing experimental results in particle physics. Experiments as BaBar, Belle and LHCb have measured a consistent tension with the standard model. In this work we study a consequence of different solutions to this tension as a sequential $\mathrm{W}'$ boson, EFT and leptoquark. Such models, are not only able to explain the $R_{D^{(\ast)}}$ anomaly but also to produce distinctive signatures at the LHC. We proposed a search for the signature $\mathrm{b},\tau,p_{T}^{miss}$ maximizing the statistical significance with regard to standard model backgrounds as $W^{\pm} + \text{jets}$, $Z^{0} + \text{jets}$ and $t\bar{t}$. We finally show how the different models require a differentiated selection criteria and the exclusion that can be achieved.

Statistical techniques in data analysis: curve fitting, p-values, bin-bin likelihood, exclusion limits setting, part II

• Carlos Andrés Florez Bustos (Universidad de los Andes)

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Introduction to Cosmological perturbations

• Juan Pablo Beltran (Universidad Nacional)

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Machine learning methods for high energy physics

• Manuel Fernando Sanchez Alarcon (Universidad de los Andes)

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Status of BSM searches at the LHC

• Carlos Andrés Florez Bustos (Universidad de los Andes)

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A brief intro to SARAH, SPHENO, FEYNRULES

• Diego Restrepo (Universidad de Antioquia)

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Inferring $S_8(z)$ and $\gamma (z)$ with cosmic growth rate measurements using machine learning

• Alexander Bonilla Rivera (Universidad Distrital Francisco José de Caldas)

Room: --- Measurements of the cosmological parameter $S_8$ provided by cosmic microwave background and large scale structure data reveal some tension between them, suggesting that the clustering features of matter in these early and late cosmological tracers could be different. In this work, we use a supervised learning method designed to solve Bayesian approach to regression, known as Gaussian Processes regression, to quantify the cosmic evolution of $S_8$ up to $z \sim 1.5$. For this, we propose a novel approach to find firstly the evolution of the function $\sigma _8(z)$, then we find the function $S_8(z)$. As a sub-product we obtain a minimal cosmological model-dependent $\sigma _8 (z=0)$ and $S_8 (z=0)$ estimates. We select independent data measurements of the growth rate f(z) and of [f \sigma _8](z) according to criteria of non-correlated data, then we perform the Gaussian reconstruction of these data sets to obtain the cosmic evolution of $\sigma _8(z)$, $S_8(z)$, and the growth index $\gamma (z)$. Our statistical analyses show that $S_8(z)$ is compatible with Planck $\Lambda$CDM cosmology; when evaluated at the present time we find $\sigma _8(z=0) = 0.766 \pm 0.116 \sigma$ and $S_8(z=0) = 0.732 \pm 0.115 \sigma$. Applying our methodology to the growth index, we find $\gamma (z=0) = 0.465 \pm 0.140$. Moreover, we compare our results with others recently obtained in the literature. In none of these functions, i.e. $\sigma _8(z)$, $S_8(z)$, and $\gamma (z)$, do we find significant deviations from the standard cosmology predictions.

Analysis of the mechanisms of dark matter production in the early universe

• Mateo Escorcia (Universidad del Atlántico)

Room: --- We work on three specific production models. The first and the most recognized is the Weakly Interacting Massive Particles or WIMP model, which we will work on by applying the Boltzmann equations to study the behavior of WIMP relics in the thermal bath during the first moments of the universe. This analysis is done by finding an approximate solution analytically and numerically using Python programming. We then adapt the calculations to characterize the Feebly Interacting Massive Particles or FIMP and Strongly Interacting Massive Particles or SIMP mechanisms.

Improving Signal Significance of SUSY

• Jorge Fraga (Universidad de los Andes)

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Triplet vector boson and the flavor anomalies

• Eduardo Rojas Peña (Universidad de Nariño)

Room: --- The triplet vector boson (TVB) is a simplified new physics model involving massive vector bosons transforming as a weak triplet vector, which it has been proposed as a combined explanation to the anomalous b→sμ+μ− and b→cτν¯τ data (the so-called B meson anomalies). In this work, we carry out an updated view of the TVB model, including the Belle II perspectives. We perform a global fit to explore the allowed parameter space by the most current b→sμ+μ− and b→cτν¯τ data, by considering all relevant low-energy flavor observables. Our results are confronted with the most recent LHC constraints. We also incorporate in our study the first measurement on the ratio R(Λc)=BR(Λb→Λcτν¯τ)/BR(Λb→Λcμν¯μ) very recently obtained by LHCb. In particular, we show that the TVB model can provide an explanation to the B meson anomalies; however, this framework is in strong tension with LHC bounds. In respect to future flavor measurements at Belle II, our results suggest that a small new physics window would be allow to solely explain the b→cτν¯τ data in agreement with LHC constraints. Furthermore, the implications of our phenomenological analysis of the TVB model to some known flavor parametrizations are also discussed.

Desigualdad de Leggett-Garg en mecánica cuántica

• Ricardo Jose Zamora Barrios (Universidad del Atlántico)

Room: --- El objetivo principal es exponer los límites de la mecánica cuántica con ayuda de la desigualdad de Leggett-Garg, utilizando el fenómeno de oscilación de neutrinos como mediador entre los dos, el cual se fundamenta en el cambio de estado de sabor, fenómeno que corresponde a una superposición coherente de los estados de masa. La meta es estudiar la violación de la desigualdad de Leggett-Garg con neutrinos, debido al hecho de que la longitud de coherencia cuántica en la que se produce la interferencia de los estados de masa y se observa el fenómeno de oscilación, se extiende a distancias considerablemente grandes, lo cual será beneficioso para ampliar el entendimiento que se tiene sobre los límites de la naturaleza entre lo clásico y lo cuántico.

Dark Matter production in non-standard cosmologies

• Valentina Franco Velásquez (Universidad de Antioquia)

Room: --- In the standard cosmological scenario, it is proposed a Universe dominated by radiation just after the inflationary phase and prior to Big Bang Nucleosynthesis (BBN) but actually, there is not much observational information supporting this hypothesis. This research project is intended to take advantage of this gap in our knowledge of cosmic history to modify the post-inflationary period and alter Dark Matter (DM) production through the introduction of a time-dependent inflaton decay rate. The existence of DM in the Universe has been one of the open and more relevant questions in physics and astronomy in the last decades. There are a large number of gravitational evidence about its existence, but there is no conclusive evidence about its nature as a particle. Through the previous decades, a worldwide program focused on discovering this particle has been carried out following three major strategies: direct detection, indirect detection, and production at colliders. Despite the great effort, the DM particle nature remains one of the central mysteries in physics. The important thing is that there is no particle belonging to the Standard Model (SM) of particle physics with the required properties to explain the observed astrophysical phenomena related to DM. Until relatively recently the DM models proposed hinged on a standard cosmology basis, however, due to the enormous difficulty present in detecting this particle, it was evident the necessity to introduce models in different scenarios. According to standard cosmology, the Universe has undergone a series of stages characterized by definite processes and the domination of one component over the rest during its evolution. Summarizing, in its first seconds, the Universe went through three main periods, inflation, reheating, and BBN. In the standard scenario, during inflation, a Universe dominated by a scalar field is hypothesized followed by a period of radiation domination from the end of reheating until BBN. However, there are no reasons to assume that the Universe was radiation-dominated prior to BBN simply because at the moment we do not have much observational information about this period and, in this sense, it is, therefore, possible that the cosmological history featured, for example, an additional early matter-dominated epoch due to e.g. slow post-inflationary reheating or massive metastable particles that dominated the total energy density. Even more exotic scenarios that change the expansion history of the Universe compared to the standard radiation-dominated case can also be realized, all of them are called non-standard cosmologies and they can have significant consequences for the physics of the early Universe. One of the most interesting consequences concerning non-standard cosmologies is that early periods in these scenarios can alter the cosmological abundances of particle species. In particular, they can have a significant impact on our expectations for the DM relic abundance, since non-standard eras can change the expansion rate of the Universe, leading to entropy injections that may dilute the DM relic abundance, or provide a non-thermal production mechanism for DM. In the frame of the present work, it is pretended to develop the phenomenology of a simplified WIMP DM model in a non-standard cosmology with a matter-dominated Universe in the period ranging from the end of inflation and the end of reheating and with a generic time-dependent rate for dissipation of matter into radiation. The main goal of this research project is to find the parameter space for a WIMP particle in the proposed frame able to account for 85% of DM in the Universe and evade the constraints imposed by experiments.

Expansión acelerada tardía del universo en un modelo de gravitación modificada tipo f(R,G) con acoplamiento a campos escalares

• Carlos Alberto Meza Morales (Universidad del Atlántico)

Room: --- En este trabajo, se estudia la expansión acelerada tardía del universo en un modelo de gravitación modificada tipo f (R, G) con acoplamiento de un campo escalar a la invariante de Gauss-Bonnet. En este sentido se consideran algunas propuestas para f(R) del tipo exponencial en el escalar de curvatura R. En primera instancia se obtienen las ecuaciones generales de movimiento asociadas al modelo propuesto, las cuales se expresan mejor de manera conveniente en términos de la cantidad statefinder yH(z) que se usa con frecuencia en la literatura, posteriormente se resuelven numéricamente considerando condiciones iniciales motivadas físicamente, valores apropiados de los parámetros del modelo para las tres propuestas que se tienen de la función f(R) y distintas formas para el potencial del campo escalar y la función de acoplamiento a la invariante de Gauss-Bonnet. Por último, se verifica si para las distintas propuestas de f(R) la fenomenología resultante es compatible con los últimos datos de la colaboración Planck 2018, además los resultados obtenidos se comparan con los correspondientes al modelo Lambda-CDM".

Neutrino Physics and Experiments

• Mario Acero (Universidad del Atlántico)

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Dune Physics goals and experiment status

• Deywis Moreno (Universidad Antonio Nariño)

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Higgs Discovery at the LHC

• Oliver Buchmueller (Imperial College)

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Gravitational waves & fundamental physics with quantum technology

• Oliver Buchmueller (Imperial College)

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Particle accelerators present and future

• Bernardo Gomez (Universidad de los Andes)

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Introduction to Coffea and its applications to high energy physics

• Daniel Ocampo-Henao (Universidad de Antioquia)

Room: --- Columnar analysis is a paradigm that describes the way the user writes the analysis application that is best described in contrast to the the traditional paradigm in high-energy particle physics (HEP) of using an event loop. Coffea is a prototype package for pulling together all the typical needs of a high-energy collider physics (HEP) analysis. In this talk I will provide an introduction to Coffea and it's functionalities, and show how to implement a basic analysis.

Estimación de nitrógeno en suelo seco

• Luigui Joel Miranda Leuro (Universidad EAFIT/Universidad Industrial de Santander)

Room: --- Dentro de la innovación del sector agrícola se presenta la agricultura de precisión, cuyo principio básico es aplicar los insumos agrarios en los lugares y momentos adecuados. El nitrógeno es uno de los elementos fundamentales para los procesos metabólicos de las plantas y es un recurso limitado en el suelo de cultivo; es aquí donde radica la importancia de captar su concentración en el suelo. Para encontrar un observable asociado al porcentaje de nitrógeno presente en el suelo seco usando astroparticulas; se simuló con ayuda el software GEANT4 la interacción del flujo de rayos cósmicos secundarios a la altura de Bucaramanga (956 m s.n.m que consta de 3855333 particulas*m^2*hora) con un bloque de volumen de 1m^3, al que se le asigna el material “suelo seco” y al cual se le variaba el porcentaje de nitrógeno por unidad de volumen (0.01%, 0.05%, 0.1%, 0.5%, 1%, 5%, 10% y 20%). A partir del espectro de energía asociado a los gammas producidos en la interacción del flujo de rayos cósmicos secundarios con el suelo seco, observamos las líneas espectrales correspondientes al nitrógeno (1.884 MeV, 3.677 MeV, 4.508 MeV, 5.627 MeV, 6.322 MeV y 10.829 MeV). Al variar el porcentaje de nitrógeno presente en el modelo de suelo seco, observamos un cambio en la amplitud de la última línea espectral. La diferencia porcentual relativa del número de gamas, producidos en una hora de interacción del flujo con un modelo de suelo con 0.01% de nitrógeno, es de 50.8% respecto a un suelo con 20% de nitrógeno. Por lo tanto, esta variación se puede considerar como una observable para determinar el porcentaje de nitrógeno presente en suelos.

Atmospheric muon flux measurement near Earth's equatorial line

• Cristian Borja (Universidad de los Andes)

Room: --- We report measurements of muon flux over the sky of the city of Bogotá at 4${^\circ}$ 35' 56'' north latitude, 74${^\circ}$ 04' 51'' west longitude, and an altitude of 2657 meters above sea level, carried out with a hodoscope composed of 4 stations of plastic scintillators located equidistant over a distance of 4.8 meters. Measurements were taken at different zenith ($\theta$) angles within the range $1.5^{\circ}\le \theta \le 90^{\circ}$, the muon flux data is statistically consistent with a $cos^2\theta$ dependence, with a $\chi^2$ per degree of freedom near unity. If instead, we fit to a $cos^n\theta$ we obtain $n=2.145 \pm 0.046$ with a lower $\chi^2$ per degree of freedom. Integrating the muon flux distribution as a function of the zenith angle over the solid angle of the upper Earth´s hemisphere allows an estimation of the atmospheric vertical muon rate at the altitude and latitude of Bogota obtaining a value of $255.1 \pm 5.8$ $ \text{m}^{-2}\text{s}^{-1}$. This estimate is consistent with an independent direct measurement of the vertical muon flux with all detectors stacked horizontally. These measurements play a key role in the further development of detectors, aimed to perform muon imaging of Monserrate Hill, located in Bogota, where the detectors will be placed at similar locations to those used in the present study.

Classification of 331 models

• Eduard Suarez Ardila (universidad de Nariño)

Room: --- The 331 models are of great interest from the theoretical and experimental point of view, since they allow explaining, among other things, the reason why there must be three families of fermions in nature and, on the other hand, they have experimental parameters that can be bounded in particle accelerators like the LHC. In general, these models are not universal and therefore have neutral currents with changes of flavor (flavor changing neutral currents FCNC) for the fermions of the model, to difference from universal models. This characteristic makes them relevant for the study of the phenomenology of the flavor physics. In particular we are interested in the classification of all 331 models for the parameter β = 3/2 and in the restrictions experimental on these.