Biblioteca Digital

O modelo padrão das partículas elementares, baseado na invariância de Lorentz e na simetria de gauge SU(3)c Ä SU(2)L Ä U(1)Y, foi confirmado por todos os testes experimentais até o momento. No entanto, nada nos garante que é este o modelo final das interações fundamentais. Problemas teóricos como a hierarquia, o número de gerações de partículas e a assimetria bariônica e alguns dados experimentais (neutrinos massivos, matéria e energia escura) sugerem a necessidade de física além do Modelo Padrão (SM). Alguns destes problemas são resolvidos em uma importante classe de modelos, que assumem a existência de simetrias espaciais adicionais, chamada de supersimetria. A proposta deste projeto é estudar a idéia de supersimetria e sua possível relevância para a física além do Modelo Padrão. Para entendermos o princípio da supersimetria, iremos construir o Modelo Padrão Supersimétrico Mínimo (MSSM) e apresentar algumas de suas conseqüências fenomenológicas. Também serão apresentados os modelos mSUGRA e mGMSB, assim como algumas de suas principais características. Em Anexo apresentaremos algumas informações complementares, além de um trabalho desenvolvido em paralelo com o projeto de Mestrado; The standard model of elementary particles...

In this thesis, I show some of the results of my research work in the field at the crossing between Cosmology and Particle Physics. The Cosmology of several models of the Physics Beyond the Standard Model is studied. These range from an inflationary model based on the condensation of a ghost-like scalar field, to several models motivated by the possibility that our theory is described by a landscape of vacua, as probably implied by String Theory, which have influence on the theory of Baryogenesis, of Dark Matter, and of Big Bang Nucleosynthesis. The analysis of the data of the experiment WMAP on the CMB for the search of a non-Gaussian signal is also presented and it results in an upper limit on the amount on non-Gaussianities which is at present the most precise and extended available.; by Leonardo Senatore.; Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2006.; Includes bibliographical references (p. 182-186).

The objective of this paper is to describe a development of an innovative approach to enable students studying science, technology, engineering, and mathematics (STEM) to apply the concepts learned in physics and mathematics to engineering problem-solving challenges. Our goal is to facilitate students transfer of knowledge from theory to engineering applications, thereby increasing student academic performance, retention, persistence, and graduation. To achieve the goal we are creating a virtual community of students and faculty as a vehicle for promoting the transfer of knowledge using e-learning and e-teaching mechanisms.; Comment: Proceedings of the International Conference on Knowledge Generation, Communication and Management: KGCM 2007, July 8-11, 2007. Orlando, Florida, USA, Vol. 3 (2007) 234-239

In a first course to classical mechanics elementary physical processes like elastic two-body collisions, the mass-spring model, or the gravitational two-body problem are discussed in detail. The continuation to many-body systems, however, is defered to graduate courses although the underlying equations of motion are essentially the same and although there is a strong motivation for high- school students in particular because of the use of particle systems in computer games. The missing link between the simple and the more complex problem is a basic introduction to solve the equations of motion numerically which could be illustrated, however, by means of the Euler method. The many-particle physics simulation package MPPhys offers a platform to experiment with simple particle simulations. The aim is to give a principle idea how to implement many-particle simulations and how simulation and visualization can be combined for interactive visual explorations.; Comment: 10 pages, 14 figures

The physics of randomness and regularities for languages (mother tongues) and their lifetimes and family trees and for the second languages are studied in terms of two opposite processes; random multiplicative noise [1], and fragmentation [2], where the original model is given in the matrix format. We start with a random initial world, and come out with the regularities, which mimic various empirical data [3] for the present languages.; Comment: 7 pages, 4 figures

Crucial physical phenomena occur in the equatorial atmosphere and ionosphere, which are currently understudied and poorly understood. Then, scientific campaigns for monitoring equatorial region are required, which will provide the data for analyzing and creating adequate models. Ecuador is located in strategic geographical position where these studies can be performed, providing data for the scientific community working for understanding the nature of these physical systems. The Quito Astronomical Observatory of National Polytechnic School is working in this direction, promoting research in Space Sciences for studying the equatorial zone. With the participation and valuable collaboration of international initiatives like AWESOME, MAGDAS, SAVNET and CALLISTO, the Quito Observatory is creating a new space physics division on the basis of the International Space Weather Initiative. In this contribution, the aforementioned initiative is presented inviting leaders from others scientific projects to deploy their instruments and to join us giving the necessary support for the creation of this new strategic research center.

This is a report of a course on modern physics designed and taught to undergraduate science and engineering students in the Spring of 2013. The course, meant for freshmen, attempts to integrate statistical mechanics into non-classical physics and introduces some novel teaching ideas such as the field approach in contrast to typical wave and particle viewpoints traditionally covered in usual textbooks. The various modern applications of quantum theory in realizing practical devices are recounted in a way that is amenable to beginners. Especially, we describe the inclusion of visually appealing and carefully designed robust experiments inside the formal classroom environment. This collection of applications and demonstrations serves as a useful collection of teaching aids and can be easily transformed into active learning exercises. The impact of this teaching strategy on student learning and its role in exciting an interest in physics is assessed.; Comment: 11 pages, 11 figures, submitted to The Physics Teacher

This study investigates how an urban, high school physics class responded to the inclusion of a classroom set of iPads and associated applications, such as screencasting. The participatory roles of students and the expressions of their relationships to physics were examined. Findings suggest that iPad technology altered classroom norms and student relationships to include increased student agency and use of evidence. Findings also suggest that the iPad provided a connection between physics, social status, and play. Videos, observations, interviews, and survey responses were analyzed to provide insight into the nature of these changes.; Comment: 4 pages, 6 figures, Physics Education Research Conference Proceedings

Commercial video games are increasingly using sophisticated physics simulations to create a more immersive experience for players. This also makes them a powerful tool for engaging students in learning physics. We provide some examples to show how commercial off-the-shelf games can be used to teach specific topics in introductory undergraduate physics. The examples are selected from a course taught predominantly through the medium of commercial video games.; Comment: Accepted to Physics Education, Fig1 does not render properly in this version

We review the development of random-matrix theory (RMT) during the last decade. We emphasize both the theoretical aspects, and the application of the theory to a number of fields. These comprise chaotic and disordered systems, the localization problem, many-body quantum systems, the Calogero-Sutherland model, chiral symmetry breaking in QCD, and quantum gravity in two dimensions. The review is preceded by a brief historical survey of the developments of RMT and of localization theory since their inception. We emphasize the concepts common to the above-mentioned fields as well as the great diversity of RMT. In view of the universality of RMT, we suggest that the current development signals the emergence of a new "statistical mechanics": Stochasticity and general symmetry requirements lead to universal laws not based on dynamical principles.; Comment: 178 pages, Revtex, 45 figures, submitted to Physics Reports

The activities carried out by Italian physicists in the field of semiconductor physics during the period spanning from 1945 to the foundation of the National Group of Structure of the Matter (GNSM, 1965) are reviewed within their historical context. Until the fifties, the Italian research was only marginally involved, if at all, in the main streams of advancement in solid state physics. Starting from the early fifties, an interest for technical applications of the newly introduced semiconductor devices began to grow in the electronic engineering community. In the following years, the birth of a few experimental and theoretical groups lead by highly motivated scientists (some of them with international experience) allowed to deal with the main topics related to condensed matter and semiconductor phenomena. The work developed by these "pioneers", discussed in this paper, represented an invaluable contribution for the new generations of physicists in this research field.; Comment: 26 pages

It is known that Einstein's conceptual base for his theory of relativity was the philosophy formulated by Immanuel Kant. Things appear differently to observers in different frames. However, Kant's Ding-an-Sich leads to the existence of the absolute reference frame which is not acceptable in Einstein's theory. It is possible to avoid this conflict using the ancient Chinese philosophy of Taoism where two different views can co-exist in harmony. This is not enough to explain Einstein's discovery of the mass-energy relation. The energy-momentum relations for slow and ultra-fast particles take different forms. Einstein was able to synthesize these two formulas to create his energy-mass relation. Indeed, this is what Hegelianism is about in physics. Isaac Newton synthesized open orbits for comets and closed orbits for planets to create his second law of motion. Maxwell combined electricity and magnetism to create his four equations to the present-day wireless world. In order to synthesize wave and particle views of matter, Heisenberg formulated his uncertainty principle. Relativity and quantum mechanics are the two greatest theories formulated in the 20th Century. Efforts to synthesize these two theories are discussed in detail.; Comment: Latex 10 pages with 6 figures...

We demonstrate the implementation of a simple time-of-flight (ToF) mass spectrometer with medium-mass resolution ($m/\Delta m\sim50$) geared towards the demands of atomic, molecular, and chemical physics experiments. By utilizing a novel radial ion extraction scheme from a linear quadrupole trap, a device with large trap capacity and high optical access is realized without sacrificing mass resolution. Here we describe the construction and implementation of the device as well as present representative ToF spectra. We conclude by demonstrating the flexibility of the device with proof-of-principle experiments that include the observation of molecular-ion photodissociation and the measurement of trapped-ion chemical reaction rates.; Comment: 7 pages, 7 figures

In active engagement physics classrooms, students get opportunities to make sense of physics together through discussion. They do not always take up these opportunities, in part because of the risk of sharing their ideas and having them rejected by their classmates or the instructors. In this case study, I analyze videotaped discourse of a tutorial group's early discussions to investigate how students manage these risks in creating a safe space to sensemake. I find that the students and instructors alike rely on a common discursive resource - epistemic distancing - to share their ideas while protecting themselves affectively if others disagree. Epistemic distancing includes hedging, joking, deferring, and other discourse moves used to soften one's stance in conversation. I use video analysis to illustrate the effects of these moves on tutorial groups' sensemaking discussions, and discuss implications for instructors wishing to encourage sensemaking discussions in their physics classrooms.; Comment: preprint of a paper submitted to the Physics Education Research Conference 2015, 4 pages, 1 figure

We discuss a detailed weak scaling analysis of GEM, a 3D MPI-parallelised gyrofluid code used in theoretical plasma physics at the Max Planck Institute of Plasma Physics, IPP at Garching b. M\"unchen, Germany. Within a PRACE Preparatory Access Project various versions of the code have been analysed on the HPC systems SuperMUC at LRZ and JUQUEEN at J\"ulich Supercomputing Centre (JSC) to improve the parallel scalability of the application. The diagnostic tool Scalasca has been used to filter out suboptimal routines. The code uses the electromagnetic gyrofluid model which is a superset of magnetohydrodynamic and drift-Alfv\'en microturbulance and also includes several relevant kinetic processes. GEM can be used with different geometries depending on the targeted use case, and has been proven to show good scalability when the computational domain is distributed amongst two dimensions. Such a distribution allows grids with sufficient size to describe small scale tokamak devices. In order to enable simulation of very large tokamaks (such as the next generation nuclear fusion device ITER in Cadarache, France) the third dimension has been parallelised and weak scaling has been achieved for significantly larger grids.; Comment: 9 pages, 6 figures...

The basic ingredients of the discovery creativity is presented. Understanding, problem solving, heuristics, computer thinking, technology and physics, and so on. We present some discoveries from the viewpoint of creativity. The Dirac equation, the Riccati equation, the nonlinear Schroedinger equation, the quantum navier Sokes equation, the equation of the quantum magnetohydrodynamics and so on. We discuss nonlinear Lorentz transformation involving the maximal acceleration which we relate to the Hagedorn temperature, and possible dependence of mass on acceleration. We consider the relation between physics and technology and so on.; Comment: 37 pages

We discuss and analyze the fact that physics is generally losing its ability to captivate students who may possess the potential to enhance the quality of our future in this age of technology. We have tried to investigate the reasons behind this low enrollment in the light of the results of a few surveys with the undergraduate students in different physics courses and in current relevant college programs. It is not an exclusively descriptive issue, so our analysis is a way to delineate the details of the matter leading to the suggestions for future improvements.; Comment: 22 pages

This thesis contains studies of phenomenological aspects of new physics at hadron colliders, such as the Large Hadron Collider (LHC). After a general introduction in chap- ter 1, in chapter 2 we outline the main features of the Standard Model (SM) of particle physics and the theoretical motivations for going beyond it. We subsequently provide brief descriptions of a few popular models that aim to solve the issues that arise within the SM. In chapter 3 we describe the general Monte Carlo method for evaluating multidimen- sional integrals and show how it can be used to construct a class of computational tools called Monte Carlo event generators. We describe the main generic features of event generators and how these are implemented in the HERWIG++ event generator. By applying resummation techniques, we provide, in chapter 4, analytical calcula- tions of two types of hadron collider observables. The first, global inclusive variables, are observables that make use of all measured particle momenta and can provide useful information on the scale of new physics. The second observable is the transverse energy of the QCD initial state radiation (ET ), associated with the either Drell-Yan gauge boson production or Higgs boson production. In both cases we provide comparisons to results obtained from Monte Carlo event generators. In chapter 5 we examine two well-motivated models for new physics: one of new heavy charged vector bosons (W prime)...

The videos posted on YouTube can be very helpful to teach any subject in the classroom. In Physics, there is a wealth of material just waiting for the teachers to know what to do with them. In this study, we present a report on how we used videos of magic performances as a teaching aid to supplement Physics classes. Since the goal of magic is to challenge a principle or a natural law, it is interesting to use it in order to try to unravel its secret in a scientific way. To illustrate the application of this strategy, we used a performance of the magician Dynamo, held in London, where he quietly walks on the water of the River Thames. Having overcome the surprise of illusion, students are led by the teacher to try to get a physically plausible explanation for the secret of the magic. To carry out this task, we followed the paths of so-called scientific method in their traditionally defined form in schoolbooks. The results are very positive as and clearly point out the engagement of students in the search for the correct explanation. This strategy is recommended for use in high school Physics classes and in the initial semesters in College courses.; http://dx.doi.org/10.5007/2175-7941.2015v32n2p483Os vídeos postados no YouTube podem ser muito úteis em sala de aula...

This paper describes how was implemented a computer simulation of an ionizing radiation detection system similar to those found in traditional modern physics laboratories. The simulation models a system with radioactive “sources” of photons with well-defined energies and a “detector” that behaves like a photon spectrometer (scintillator + photomultiplier tube + multichannel analyzer). As with the real system, besides choosing the source, it is possible to adjust the high voltage applied at the photomultiplier tube, the gain of the analog amplifier and the conversion gain of the multichannel analyzer, observing the corresponding changes in the acquired “data”. There are presented and discussed results obtained with the simulator for some experimental set-ups (energy calibration, identification of unknown energies, system energy resolution, etc.). The simulation was used with two groups of undergraduate students from a distance learning physics course at UFSC in 2011 and 2014, along with the execution of the real experiment. Throughout the text there are comments on the motivations and problems of using simulations in this context. Finally, it is discussed how this work relates to the main goals of introductory physics laboratories...