Santiago Pérez, Camila Gómez, Matías Rodríguez
This study explores a comprehensive approach to obstacle detection using advanced YOLO models, specifically YOLOv8, YOLOv7, YOLOv6, and YOLOv5. Leveraging deep learning techniques, the research focuses on the performance comparison of these models in real-time detection scenarios. The findings demonstrate that YOLOv8 achieves the highest accuracy with improved precision-recall metrics. Detailed training processes, algorithmic principles, and a range of experimental results are presented to validate the model's effectiveness.
Santiago Perez, Dario Rodrigues, Juan Estrada, Roni Harnik, Zhen Liu, Brenda A. Cervantes-Vergara, Juan Carlos D'Olivo, Ryan D. Plestid, Javier Tiffenberg, Tien-Tien Yu, Alexis Aguilar-Arevalo, Fabricio Alcalde-Bessia, Nicolas Avalos, Oscar Baez, Daniel Baxter, Xavier Bertou, Carla Bonifazi, Ana Botti, Gustavo Cancelo, Nuria Castelló-Mor, Alvaro E. Chavarria, Claudio R. Chavez, Fernando Chierchie, Juan Manuel De Egea, Cyrus Dreyer, Alex Drlica-Wagner, Rouven Essig, Ezequiel Estrada, Erez Etzion, Paul Grylls, Guillermo Fernandez-Moroni, Marivi Fernández-Serra, Santiago Ferreyra, Stephen Holland, Agustín Lantero Barreda, Andrew Lathrop, Ian Lawson, Ben Loer, Steffon Luoma, Edgar Marrufo Villalpando, Mauricio Martinez Montero, Kellie McGuire, Jorge Molina, Sravan Munagavalasa, Danielle Norcini, Alexander Piers, Paolo Privitera, Nathan Saffold, Richard Saldanha, Aman Singal, Radomir Smida, Miguel Sofo-Haro, Diego Stalder, Leandro Stefanazzi, Michelangelo Traina, Yu-Dai Tsai, Sho Uemura, Pedro Ventura, Rocío Vilar Cortabitarte, Rachana Yajur
Oscura is a planned light-dark matter search experiment using Skipper-CCDs with a total active mass of 10 kg. As part of the detector development, the collaboration plans to build the Oscura Integration Test (OIT), an engineering test with 10% of the total mass. Here we discuss the early science opportunities with the OIT to search for millicharged particles (mCPs) using the NuMI beam at Fermilab. mCPs would be produced at low energies through photon-mediated processes from decays of scalar, pseudoscalar, and vector mesons, or direct Drell-Yan productions. Estimates show that the OIT would be a world-leading probe for mCPs in the MeV mass range.
Alexis Aguilar-Arevalo, Fabricio Alcalde Bessia, Nicolas Avalos, Daniel Baxter, Xavier Bertou, Carla Bonifazi, Ana Botti, Mariano Cababie, Gustavo Cancelo, Brenda Aurea Cervantes-Vergara, Nuria Castello-Mor, Alvaro Chavarria, Claudio R. Chavez, Fernando Chierchie, Juan Manuel De Egea, Juan Carlos D`Olivo, Cyrus E. Dreyer, Alex Drlica-Wagner, Rouven Essig, Juan Estrada, Ezequiel Estrada, Erez Etzion, Guillermo Fernandez-Moroni, Marivi Fernandez-Serra, Steve Holland, Agustin Lantero Barreda, Andrew Lathrop, Jose Lipovetzky, Ben Loer, Edgar Marrufo Villalpando, Jorge Molina, Santiago Perez, Paolo Privitera, Dario Rodrigues, Richard Saldanha, Diego Santa Cruz, Aman Singal, Nathan Saffold, Leandro Stefanazzi, Miguel Sofo-Haro, Javier Tiffenberg, Christian Torres, Sho Uemura, Rocio Vilar
Feb 21, 2022·astro-ph.IM·PDF The Oscura experiment will lead the search for low-mass dark matter particles using a very large array of novel silicon Charge Coupled Devices (CCDs) with a threshold of two electrons and with a total exposure of 30 kg-yr. The R&D effort, which began in FY20, is currently entering the design phase with the goal of being ready to start construction in late 2024. Oscura will have unprecedented sensitivity to sub-GeV dark matter particles that interact with electrons, probing dark matter-electron scattering for masses down to 500 keV and dark matter being absorbed by electrons for masses down to 1 eV. The Oscura R&D effort has made some significant progress on the main technical challenges of the experiment, of which the most significant are engaging new foundries for the fabrication of the CCD sensors, developing a cold readout solution, and understanding the experimental backgrounds.
Liron Barak, Itay M. Bloch, Ana M. Botti, Mariano Cababie, Gustavo Cancelo, Luke Chaplinsky, Michael Crisler, Alex Drlica-Wagner, Rouven Essig, Juan Estrada, Erez Etzion, Guillermo Fernandez Moroni, Roni Harnik, Stephen E. Holland, Yaron Korn, Zhen Liu, Sravan Munagavalasa, Aviv Orly, Santiago E. Perez, Ryan Plestid, Dario Rodrigues, Nathan A. Saffold, Silvia Scorza, Aman Singal, Miguel Sofo Haro, Leandro Stefanazzi, Kelly Stifter, Javier Tiffenberg, Sho Uemura, Tomer Volansky, Tien-Tien Yu
Millicharged particles appear in several extensions of the Standard Model, but have not yet been detected. These hypothetical particles could be produced by an intense proton beam striking a fixed target. We use data collected in 2020 by the SENSEI experiment in the MINOS cavern at the Fermi National Accelerator Laboratory to search for ultra-relativistic millicharged particles produced in collisions of protons in the NuMI beam with a fixed graphite target. The absence of any ionization events with 3 to 6 electrons in the SENSEI data allow us to place world-leading constraints on millicharged particles for masses between 30 MeV to 380 MeV. This work also demonstrates the potential of utilizing low-threshold detectors to investigate new particles in beam-dump experiments, and motivates a future experiment designed specifically for this purpose.
Santiago Esteban Perez Bergliaffa, Yves Eduardo Chifarelli de Oliveira Nunes
We study some features of static and spherically symmetric solutions (SSS) with a horizon in $f(R)$ theories of gravitation by means of a near-horizon analysis. A necessary condition for an $f(R)$ theory to have this type of solution is obtained. General features of the effective potential are deduced, and it is shown that there exists a limit on the curvature at the horizon, in both cases for any $f(R$). Finally, we calculate the expression for the energy of the collision of two masive particles in the center of mass frame.
E. C. Valadão, Felipe Sobrero, Santiago Esteban Perez Bergliaffa
The Lyra geometry provides an interesting approach to develop purely geometrical scalar-tensor theories. Here we present a theory on Lyra manifolds which contains generalizations of both Brans-Dicke gravity and Einstein-Gauss-Bonnet scalar-tensor theory. It is shown that the symmetry group of gravitational theories on the Lyra geometry comprises not only coordinate transformations but also local transformations of length units, so that the Lyra function is a conformal factor which locally fixes the unit of length. The Lyra geometry is thus a generalization of Riemannian geometry which includes spacetime-dependent length units. By performing a Lyra transformation to a frame in which the unit of length is globally fixed, it is shown that General Relativity (GR) is obtained from the Lyra Scalar-Tensor Theory (LyST). Through the same procedure, even in the presence of matter fields, it is found that Brans-Dicke gravity and the Einstein-Gauss-Bonnet scalar-tensor theory are obtained from their Lyra counterparts. It is argued that this approach is consistent with the Mach-Dicke principle, since the strength of gravity in Brans-Dicke-Lyra is controlled by the scale function. It might be possible that any known scalar-tensor theory can be naturally geometrized by considering a particular Lyra frame, for which the scalar field is the function which locally controls the unit of length. The Jordan-Einstein frame conundrum is also assessed from the perspective of Lyra transformations, it is shown that the Lyra geometry makes explicit that the two frames are only different representations of the same theory, so that in the Einstein frame the unit of length varies locally. The Lyra formalism is then shown to be better suited for exploring scalar-tensor gravity, since in its well-defined structure the conservation of the energy-momentum tensor and geodesic motion are assured in the Einstein frame.
Ernesto F. Eiroa, Griselda Figueroa-Aguirre, Miguel L. Peñafiel, Santiago E. Perez Bergliaffa
A study of the dynamical and thermodynamical stability of a charged thin-shell wormhole built by gluing two Reissner-Nordström geometries is presented. The charge on the shell is linearly related to the matter content. For the dynamical stability, a concise inequality is obtained, valid for any barotropic equation of state that relates the pressure with the energy density at the throat. A thermodynamical description of the system is introduced, which leads to the temperature and the electric potentials. Adopting a linear equation of state for the pressure and a definite form for the entropy function, the set of equilibrium configurations that are both dynamically and thermodynamically stable is found.
Elcio Abdalla, Guillermo Franco Abellán, Amin Aboubrahim, Adriano Agnello, Ozgur Akarsu, Yashar Akrami, George Alestas, Daniel Aloni, Luca Amendola, Luis A. Anchordoqui, Richard I. Anderson, Nikki Arendse, Marika Asgari, Mario Ballardini, Vernon Barger, Spyros Basilakos, Ronaldo C. Batista, Elia S. Battistelli, Richard Battye, Micol Benetti, David Benisty, Asher Berlin, Paolo de Bernardis, Emanuele Berti, Bohdan Bidenko, Simon Birrer, John P. Blakeslee, Kimberly K. Boddy, Clecio R. Bom, Alexander Bonilla, Nicola Borghi, François R. Bouchet, Matteo Braglia, Thomas Buchert, Elizabeth Buckley-Geer, Erminia Calabrese, Robert R. Caldwell, David Camarena, Salvatore Capozziello, Stefano Casertano, Angela Chen, Geoff C. F. Chen, Hsin-Yu Chen, Jens Chluba, Anton Chudaykin, Michele Cicoli, Craig J. Copi, Fred Courbin, Francis-Yan Cyr-Racine, Bozena Czerny, Maria Dainotti, Guido D'Amico, Anne-Christine Davis, Javier de Cruz Pérez, Jaume de Haro, Jacques Delabrouille, Peter B. Denton, Suhail Dhawan, Keith R. Dienes, Eleonora Di Valentino, Pu Du, Dominique Eckert, Celia Escamilla-Rivera, Agnès Ferté, Fabio Finelli, Pablo Fosalba, Wendy L. Freedman, Noemi Frusciante, Enrique Gaztañaga, William Giarè, Elena Giusarma, Adrià Gómez-Valent, Will Handley, Ian Harrison, Luke Hart, Dhiraj Kumar Hazra, Alan Heavens, Asta Heinesen, Hendrik Hildebrandt, J. Colin Hill, Natalie B. Hogg, Daniel E. Holz, Deanna C. Hooper, Nikoo Hosseininejad, Dragan Huterer, Mustapha Ishak, Mikhail M. Ivanov, Andrew H. Jaffe, In Sung Jang, Karsten Jedamzik, Raul Jimenez, Melissa Joseph, Shahab Joudaki, Mark Kamionkowski, Tanvi Karwal, Lavrentios Kazantzidis, Ryan E. Keeley, Michael Klasen, Eiichiro Komatsu, Léon V. E. Koopmans, Suresh Kumar, Luca Lamagna, Ruth Lazkoz, Chung-Chi Lee, Julien Lesgourgues, Jackson Levi Said, Tiffany R. Lewis, Benjamin L'Huillier, Matteo Lucca, Roy Maartens, Lucas M. Macri, Danny Marfatia, Valerio Marra, Carlos J. A. P. Martins, Silvia Masi, Sabino Matarrese, Arindam Mazumdar, Alessandro Melchiorri, Olga Mena, Laura Mersini-Houghton, James Mertens, Dinko Milakovic, Yuto Minami, Vivian Miranda, Cristian Moreno-Pulido, Michele Moresco, David F. Mota, Emil Mottola, Simone Mozzon, Jessica Muir, Ankan Mukherjee, Suvodip Mukherjee, Pavel Naselsky, Pran Nath, Savvas Nesseris, Florian Niedermann, Alessio Notari, Rafael C. Nunes, Eoin Ó Colgáin, Kayla A. Owens, Emre Ozulker, Francesco Pace, Andronikos Paliathanasis, Antonella Palmese, Supriya Pan, Daniela Paoletti, Santiago E. Perez Bergliaffa, Leadros Perivolaropoulos, Dominic W. Pesce, Valeria Pettorino, Oliver H. E. Philcox, Levon Pogosian, Vivian Poulin, Gaspard Poulot, Marco Raveri, Mark J. Reid, Fabrizio Renzi, Adam G. Riess, Vivian I. Sabla, Paolo Salucci, Vincenzo Salzano, Emmanuel N. Saridakis, Bangalore S. Sathyaprakash, Martin Schmaltz, Nils Schöneberg, Dan Scolnic, Anjan A. Sen, Neelima Sehgal, Arman Shafieloo, M. M. Sheikh-Jabbari, Joseph Silk, Alessandra Silvestri, Foteini Skara, Martin S. Sloth, Marcelle Soares-Santos, Joan Solà Peracaula, Yu-Yang Songsheng, Jorge F. Soriano, Denitsa Staicova, Glenn D. Starkman, István Szapudi, Elsa M. Teixeira, Brooks Thomas, Tommaso Treu, Emery Trott, Carsten van de Bruck, J. Alberto Vazquez, Licia Verde, Luca Visinelli, Deng Wang, Jian-Min Wang, Shao-Jiang Wang, Richard Watkins, Scott Watson, John K. Webb, Neal Weiner, Amanda Weltman, Samuel J. Witte, Radosław Wojtak, Anil Kumar Yadav, Weiqiang Yang, Gong-Bo Zhao, Miguel Zumalacárregui
Santiago E. Perez Bergliaffa
Jan 27, 2004·astro-ph·PDF The effective metric is introduced by means of two examples (non-linear electromagnetism and hydrodynamics),along with applications in Astrophysics. A sketch of the generality of the effect is also given.
Érico Goulart, Santiago Esteban Perez Bergliaffa
It is shown here that symmetric hyperbolicity, which guarantees well-posedness, leads to a set of two inequalities for matrices whose elements are determined by a given theory. As a part of the calculation, carried out in a mostly-covariant formalism, the general form for the symmetrizer, valid for a general Lagrangian theory, was obtained. When applied to nonlinear electromagnetism linearly coupled to curvature, the inequalities lead to strong constraints on the relevant quantities, which were illustrated with applications to particular cases. The examples show that non-linearity leads to constraints on the field intensities, and non-minimal coupling imposes restrictions on quantities associated to curvature.
Erico Goulart de Oliveira Costa, Santiago Esteban Perez Bergliaffa
We show that only two types of effective metrics are possible in certain nonlinear electromagnetic theories. This is achieved by using the dependence of the effective metric on the energy-momentum tensor of the background along with the Segrè classification of the latter. Each of these forms is completely determined by single scalar function, which characterizes the light cone of the nonlinear theory. We compare this light cone with that of Minkowski in two examples.
Luz Marina Reyes, Santiago Esteban Perez Bergliaffa
We investigate whether a self-interacting Brans-Dicke theory in $d=5$ without matter and with a time-dependent metric can describe, after dimensional reduction to $d=4$, the FLRW model with accelerated expansion and non-relativistic matter. By rewriting the effective 4-dimensional theory as an autonomous three-dimensional dynamical system and studying its critical points, we show that the $Λ$CDM cosmology cannot emerge from such a model. This result suggests that a richer structure in $d=5$ may be needed to obtain the accelerated expansion as well as the matter content of the 4-dimensional universe.
Santiago E. Perez Bergliaffa
In this communication I analyze the problem of complete exceptionality of wave propagation in a class of spin 2 field theories. I show that, under the imposition of the good weak-field limit, only two Lagrangians are completely exceptional. These are the linear Fierz Lagrangian, and a Born-Infeld-like Lagrangian. As a byproduct, I reobtain the result that in a nonlinear theory, spin 2 particles follow an effective metric that depends on the nonlinearities of the Lagrangian.
Santiago Esteban Perez Bergliaffa
A short introduction to cosmological models that go from an era of accelerated collapse to an expanding era without displaying a singularity is presented.
Claudia A. Rivasplata Paz, Jose Martins Salim, Santiago Esteban Perez Bergliaffa
We study the linear stability of a nongravitating, steady-state, spherically symmetric ghost condensate accreting onto a Schwarzschild black hole using two methods. The first one is based on the conservation of the energy-momentum tensor of the perturbations (whose propagation is determined by the effective metric), and involves the determination of the sign of the time derivative of the energy of the perturbations. The second method employs the positivity of the effective potential. Both methods yield the result that the system is stable, but the second one is less practical, since it involves lengthier calculations and requires the explicit form of the background solution for the scalar field.
Santiago Esteban Perez Bergliaffa
A brief introduction to theories of the gravitational field with a Lagrangian that is a function of the scalar curvature is given. The emphasis will be placed in formal developments, while comparison to observation will be discussed in the chapter by S. Jorás in this volume.
Rana X. Adhikari, Luis A. Anchordoqui, Ke Fang, B. S. Sathyaprakash, Kirsten Tollefson, Tiffany R. Lewis, Kristi Engel, Amin Aboubrahim, Ozgur Akarsu, Yashar Akrami, Roberto Aloisio, Rafael Alves Batista, Mario Ballardini, Stefan W. Ballmer, Ellen Bechtol, David Benisty, Emanuele Berti, Simon Birrer, Alexander Bonilla, Richard Brito, Mauricio Bustamante, Robert Caldwell, Vitor Cardoso, Sukanya Chakrabarti, Thomas Y. Chen, Michele Cicoli, Sebastien Clesse, Alan Coleman, Yanou Cui, Giulia Cusin, Tansu Daylan, Keith R. Dienes, Eleonora Di Valentino, Cora Dvorkin, Celia Escamilla-Rivera, Glennys R. Farrar, Jonathan L. Feng, Noemi Frusciante, Juan Garcia-Bellido, Carlos Garcia Canal, Maria Vittoria Garzelli, Jonas Glombitza, Geraldina Golup, Maria Gritsevich, Zoltan Haiman, Jaume Haro, Dhiraj Kumar Hazra, Alan Heavens, Daniel Holz, Jorg R. Horandel, Mustapha Ishak, Mikhail M. Ivanov, Shahab Joudaki, Karl-Heinz Kampert, Christopher M. Karwin, Ryan Keeley, Michael Klasen, Rostislav Konoplich, John F. Krizmanic, Suresh Kumar, Benjamin L'Huillier, Noam Levi, Vuk Mandic, Valerio Marra, C. J. A. P. Martins, Sabino Matarrese, Eric Mayotte, Sonja Mayotte, Laura Mersini-Houghton, Joel Meyers, Andrew L. Miller, Emil Mottola, Suvodip Mukherjee, Kohta Murase, Marco Stein Muzio, Pran Nath, Ken K. Y. Ng, Jose Miguel No, Rafael C. Nunes, Angela V. Olinto, Francesco Pace, Supriya Pan, Santiago E. Perez Bergliaffa, Levon Pogosian, Jocelyn Read, Maximilian Reininghaus, Mary Hall Reno, Adam G. Riess, Mairi Sakellariadou, Alexander S. Sakharov, Paolo Salucci, Marcos Santander, Eva Santos, Fred Sarazin, Emmanuel N. Saridakis, Sergio J. Sciutto, Arman Shafieloo, David H. Shoemaker, Kuver Sinha, Dennis Soldin, Jorge F. Soriano, Denitsa Staicova, Ling Sun, D. A. Steer, Brooks Thomas, John A. Tomsick, Victor B. Valera, J. Alberto Vazquez, Tonia M. Venters, Luca Visinelli, Scott Watson, John K. Webb, Amanda Weltman, Graham White, Stephanie Wissel, Anil Kumar Yadav, Fengwei Yang, Weiqiang Yang, Nicolas Yunes, Alexey Yushkov, Haocheng Zhang
Pedro Cañate, Santiago Esteban Perez Bergliaffa
We present a procedure that transforms a singular, asymptotically flat, static and spherically symmetric black hole into a regular black hole spacetime. The regular black hole is a solution of General Relativity theory coupled to nonlinear electrodynamics (NLED), even if the original metric is not a vacuum, or electro-vacuum, solution of General Relativity (GR).
Santiago Esteban Perez Bergliaffa, Marcelo Chiapparini, Luz Marina Reyes
The dynamical stability of massive thin shells with a given equation of state (EOS) is here compared (both for the barotropic and non-barotropic case) with the results coming from thermodynamical stability. Our results show that the restrictions in the parameter space of equilibrium configurations of the shell following from thermodynamical stability are much more stringent that those obtained from dynamical stability. As a byproduct, we furnish evidence that the link between the maximum mass along a sequence of equilibrium configurations and the onset of dynamical stability is valid for EOS of the type $P=P(σ, R)$.
Nora Bretón, Santiago Esteban Perez Bergliaffa
The stability of three static and spherically symmetric black hole solutions with nonlinear electromagnetism as a source is investigated in three different ways. We show that the specific heat of all the solutions displays an infinite discontinuity with a change of sign, but the turning point method indicates that the solutions are thermodynamically stable (much in the same way as in the case of the Reissner-Nordstrom geometry). We also show that the black holes analyzed here are dynamically stable, thus suggesting that there may be a relation between thermodynamical and dynamical stability for nonvacuum black holes.