Dimiter Hadjimichef - Academia.edu (original) (raw)
Papers by Dimiter Hadjimichef
In this contribution to the Festschrift for Prof. Remo Ruffini, we investigated a formulation of ... more In this contribution to the Festschrift for Prof. Remo Ruffini, we investigated a formulation of quantum gravity based on the Wheeler-DeWitt (WDW) equation combined with the classical concepts of the branch-cut cosmology, which contemplates as a new scenario for the origin of the Universe, a smooth transition region between the contraction phase, prior to the primordial singularity, and the subsequent expansion phase. Through the introduction of an energy-dependent effective potential, which describes the space-time curvature associated with the embedding geometry and its coupling with the cosmological constant and matter fields, solutions of the WDW equation for the wave function of the Universe are obtained. The Lagrangian density is quantized through the standard procedure of raising the Hamiltonian, the helix-like complex scale factor of branched cosmology as well as the corresponding conjugate momentum to the category of quantum operators. As a novelty, ambiguities in the order...
Caderno Brasileiro de Ensino de Física
The present work deals with possibilities for contribution of the Theory of Social Representation... more The present work deals with possibilities for contribution of the Theory of Social Representations (TSR) as a reference for group learning, with techniques and methodologies that are specific to it, to facilitate the teaching of Quantum Physics in High School, allowing to investigate, for example, if students have conceptions linked to Quantum Mysticism. The main objective is to evaluate how this psychosocial theory can be used for the research community in Science Teaching. We present theoretical results, based on an analysis of the TSR and a brief literature review, as well as empirical results from the application of questionnaires in high school (Study 1, N = 291), as well as during the application of a Didactic Module in a classroom with 34 students (Study 2, N = 34). We proceeded with the construction of similarity networks via a software used in Social Psychology (IRAMuTeQ), networks that are graphic representations of a verbal association test, which can give indications of ...
Post-perihelical photometric observations of comet Halley were performed on 25 nights at the 50 c... more Post-perihelical photometric observations of comet Halley were performed on 25 nights at the 50 cm reflector of UFRGS by the technique of strip photometry. A slit of dimensions 8arcmin×8arcsec scanned the comet image at a speed of 1arcsec.345 cos delta sec-1, in east-west direction or inversely. For photometry the authors used NASA interference filters C2, C3, CO+, H2O+, lambda4845 and
Astronomische Nachrichten
Brazilian Journal of Physics
Caderno Brasileiro de Ensino de Física
Com o presente texto trazemos alguns resultados empíricos sobre percepções de estudantes de Ensin... more Com o presente texto trazemos alguns resultados empíricos sobre percepções de estudantes de Ensino Médio sobre a relação entre Ciência e Religião, bem como alguns indícios de viabilidade de atividades que foram conduzidas em uma pesquisa mais ampla, em nível de mestrado em Ensino de Física, para tratar desta relação em sala de aula. O objetivo do presente artigo é apresentar possibilidades para o Ensino de Física com viés Histórico e Epistemológico que trate da relação Ciência e Religião. Para tal, apresentamos dados coletados com estudantes de Ensino Médio sobre como estes alunos relacionam Ciência e Religião, antes de uma intervenção didática (Estudo 1, N=291) e após uma intervenção didática que abordasse o tema de forma secundária, uma vez que a ênfase foi a introdução de Física Quântica com um viés histórico (Estudo 2, N=34). Observamos se os alunos acreditavam que os cientistas (quaisquer cientistas para o Estudo 1 e os principais cientistas por trás do desenvolvimento da Quânt...
Quando os núcleons ligados num núcleo se sobrepõem, a sua estrutura interna influencia as proprie... more Quando os núcleons ligados num núcleo se sobrepõem, a sua estrutura interna influencia as propriedades nucleares. Em especial, a estatística dos quanta elementares que constituem o núcleon se torna relevante. No intuito de investigar estes efeitos no contexto dos modelos de sóliton, considera-se sistemas simples unidimensionais. No modelo de sine-Gordon, o operador de Mandelstam, que cria sólitons topológicos p ~.mtuais, é modificado de maneira a levar em conta a estrutura do sóliton. O operador resultante cria férmions de carga topológica unitária e a sua aplicação sobre o vácuo de Fock produz um estado coerente no qual o campo médio é dado pela solução solitônica clássica. Pela aplicação sucessiva dos operadores, criando sólitons centrados em pontos diferentes, obtem-se um estado coerente no qual o valor esperado do campo é dado pela soma dos campos médios individuais. No estado de dois sólitons, a energia média de interação possui um comportamento de barreira de potencial, evidenciando a repulsão entre sólitons neste modelo. Consideramos também um modelo simplificado de sóliton não - topológico constituído de um único férmion confinado por um campo escalar bosônico. Tanto no modelo topológico como no não - topológico, a variação da norma de um estado de dois sóli tons com a distância entre seus centros revela a competição entre as estatísticas fermiônicas e bosônicas. Na região de separação pequena, o aspecto fermiônico prevalece fazendo a norma do estado se aproximar de zero. Na região de separação média a norma excede a unidade devido à superposição dos quanta bosônicos.When the nucleons, bounded inside a nucleus, overlap, their internai structure affects the nuclear properties. In particular, the statistics of the elementary quanta that constitute the nucleon become relevant. In order to investigate such effects in the context of soliton models, we consider simple one-dimensional sistems. In the sine-Gordon model, the Mandelstam operator, which creates point-like topological solitons, is modifided in such a way as to account for the soliton structure. The resulting operator creates fermions with unitary topological charge and its application on the Fock vacuum produces a coherent state in which the mean field is given by the classical solitonic solution. By successive application of soliton creation operators, centered at different points, one obtains a coherent state in which the mean field is given by the sum of the individual mean fields. In the two-soliton state the mean interaction energy possesses a potential barrier behavior, displaying the repulsion between solitons in this model. Vve also consider a simplified non-topological soliton model, composed of one fermion confined in a scalar bosonic field. In the topological soliton modelas well as in the non-topological one, the variation of the norm of the two-soliton state, with the distance between their centers reveals a competition between the fermionic and bosonic statistics. In the small separation region the fermionic aspect prevails, making the norm go to zero. In the intermediate separation region, the norm exceeds unity due to the overlap of the bosonic quanta
Journal of Physics: Conference Series, 2015
The goal of this work is to establish a comparison between the very well studied 3 P0 model and a... more The goal of this work is to establish a comparison between the very well studied 3 P0 model and a bound-state corrected version, the C 3 P0 model, obtained from applying the Fock-Tani transformation to the 3 P0 model, in the context of the charmed-strange meson sector (DSJ meson). In particular, we shall calculate the decay amplitudes and decay rates of the Ds1(2460) + → D * + s π 0 and Ds1(2536) + → D * (2010) + K 0 , showing the differences between the two models.
International Journal of Modern Physics E-nuclear Physics, 2011
We investigate a double extension to the Standard Model (SM). A first extension introduces, via m... more We investigate a double extension to the Standard Model (SM). A first extension introduces, via minimal coupling, a massive Z ′ boson. This enlarged SM is coupled to a dark matter sector through the Stueckelberg mechanism by a A ′ boson. However, the A ′ boson does not interact directly with the SM fermions. In our study, we found that the A ′ is a massless photon-like particle in dark sector. Constraints on the mass for Z ′ and corrections to Z mass are obtained.
Glueball-glueball scattering in a constituent gluon model
Strange stars in the color flavor locked phase, as described by a generalization of the phenomeno... more Strange stars in the color flavor locked phase, as described by a generalization of the phenomenological MIT bag model proposed in the context of color superconductivity, are studied through a model motivated by the semiclassical solutions for hydrostatic equilibrium. Results show that within this framework it is possible to find ultracompact configurations situated between regular compact stars and black holes.
Neutron stars are the most compact objects in nature widely used in the study of dense matter phy... more Neutron stars are the most compact objects in nature widely used in the study of dense matter physics. In this work we investigate the structure of these stars, described by the Tolman-Openheimer-Volkof equations, using equations of state for both symmetric nuclear matter and quark matter. We obtain results for the mass-radius relation and then we compared ours results with the actual pulsar data recently observed PSR J1614-2230 with a mass 1.97pm0.04Modot1.97\pm 0.04\ M_{\odot}1.97pm0.04Modot.
Journal of Physics G: Nuclear and Particle Physics, 2021
International Journal of Modern Physics E
In this work we use a mapping technique to derive in the context of a constituent gluon model an ... more In this work we use a mapping technique to derive in the context of a constituent gluon model an effective Hamiltonian that involves explicit gluon degrees of freedom. We study glueballs with two gluons using the Fock-Tani formalism. In the present work we calculate the glueball-glueball potential, in the context of the constituent gluon model, with gluon interchange.
We investigate non-inertial effects on CP -violating processes using a model, based on the framew... more We investigate non-inertial effects on CP -violating processes using a model, based on the framework of quantum field theory in curved spacetimes, devised to account for the decay of accelerated particles. We show that the CP violation parameter for the decay of accelerated kaons into two pions decreases very slightly as very high accelerations are achieved, implying decreased asymmetry between matter and antimatter in this regime. We discuss the relationship between these results and cosmological processes surrounding matter-antimatter asymmetry and argue that, due to the connection between non-inertial and thermal phenomena established by the Unruh effect, this kind of computation may prove useful in furthering the understanding of thermodynamical effects in curved spacetimes.
In this contribution to the Festschrift for Prof. Remo Ruffini, we investigated a formulation of ... more In this contribution to the Festschrift for Prof. Remo Ruffini, we investigated a formulation of quantum gravity based on the Wheeler-DeWitt (WDW) equation combined with the classical concepts of the branch-cut cosmology, which contemplates as a new scenario for the origin of the Universe, a smooth transition region between the contraction phase, prior to the primordial singularity, and the subsequent expansion phase. Through the introduction of an energy-dependent effective potential, which describes the space-time curvature associated with the embedding geometry and its coupling with the cosmological constant and matter fields, solutions of the WDW equation for the wave function of the Universe are obtained. The Lagrangian density is quantized through the standard procedure of raising the Hamiltonian, the helix-like complex scale factor of branched cosmology as well as the corresponding conjugate momentum to the category of quantum operators. As a novelty, ambiguities in the order...
Caderno Brasileiro de Ensino de Física
The present work deals with possibilities for contribution of the Theory of Social Representation... more The present work deals with possibilities for contribution of the Theory of Social Representations (TSR) as a reference for group learning, with techniques and methodologies that are specific to it, to facilitate the teaching of Quantum Physics in High School, allowing to investigate, for example, if students have conceptions linked to Quantum Mysticism. The main objective is to evaluate how this psychosocial theory can be used for the research community in Science Teaching. We present theoretical results, based on an analysis of the TSR and a brief literature review, as well as empirical results from the application of questionnaires in high school (Study 1, N = 291), as well as during the application of a Didactic Module in a classroom with 34 students (Study 2, N = 34). We proceeded with the construction of similarity networks via a software used in Social Psychology (IRAMuTeQ), networks that are graphic representations of a verbal association test, which can give indications of ...
Post-perihelical photometric observations of comet Halley were performed on 25 nights at the 50 c... more Post-perihelical photometric observations of comet Halley were performed on 25 nights at the 50 cm reflector of UFRGS by the technique of strip photometry. A slit of dimensions 8arcmin×8arcsec scanned the comet image at a speed of 1arcsec.345 cos delta sec-1, in east-west direction or inversely. For photometry the authors used NASA interference filters C2, C3, CO+, H2O+, lambda4845 and
Astronomische Nachrichten
Brazilian Journal of Physics
Caderno Brasileiro de Ensino de Física
Com o presente texto trazemos alguns resultados empíricos sobre percepções de estudantes de Ensin... more Com o presente texto trazemos alguns resultados empíricos sobre percepções de estudantes de Ensino Médio sobre a relação entre Ciência e Religião, bem como alguns indícios de viabilidade de atividades que foram conduzidas em uma pesquisa mais ampla, em nível de mestrado em Ensino de Física, para tratar desta relação em sala de aula. O objetivo do presente artigo é apresentar possibilidades para o Ensino de Física com viés Histórico e Epistemológico que trate da relação Ciência e Religião. Para tal, apresentamos dados coletados com estudantes de Ensino Médio sobre como estes alunos relacionam Ciência e Religião, antes de uma intervenção didática (Estudo 1, N=291) e após uma intervenção didática que abordasse o tema de forma secundária, uma vez que a ênfase foi a introdução de Física Quântica com um viés histórico (Estudo 2, N=34). Observamos se os alunos acreditavam que os cientistas (quaisquer cientistas para o Estudo 1 e os principais cientistas por trás do desenvolvimento da Quânt...
Quando os núcleons ligados num núcleo se sobrepõem, a sua estrutura interna influencia as proprie... more Quando os núcleons ligados num núcleo se sobrepõem, a sua estrutura interna influencia as propriedades nucleares. Em especial, a estatística dos quanta elementares que constituem o núcleon se torna relevante. No intuito de investigar estes efeitos no contexto dos modelos de sóliton, considera-se sistemas simples unidimensionais. No modelo de sine-Gordon, o operador de Mandelstam, que cria sólitons topológicos p ~.mtuais, é modificado de maneira a levar em conta a estrutura do sóliton. O operador resultante cria férmions de carga topológica unitária e a sua aplicação sobre o vácuo de Fock produz um estado coerente no qual o campo médio é dado pela solução solitônica clássica. Pela aplicação sucessiva dos operadores, criando sólitons centrados em pontos diferentes, obtem-se um estado coerente no qual o valor esperado do campo é dado pela soma dos campos médios individuais. No estado de dois sólitons, a energia média de interação possui um comportamento de barreira de potencial, evidenciando a repulsão entre sólitons neste modelo. Consideramos também um modelo simplificado de sóliton não - topológico constituído de um único férmion confinado por um campo escalar bosônico. Tanto no modelo topológico como no não - topológico, a variação da norma de um estado de dois sóli tons com a distância entre seus centros revela a competição entre as estatísticas fermiônicas e bosônicas. Na região de separação pequena, o aspecto fermiônico prevalece fazendo a norma do estado se aproximar de zero. Na região de separação média a norma excede a unidade devido à superposição dos quanta bosônicos.When the nucleons, bounded inside a nucleus, overlap, their internai structure affects the nuclear properties. In particular, the statistics of the elementary quanta that constitute the nucleon become relevant. In order to investigate such effects in the context of soliton models, we consider simple one-dimensional sistems. In the sine-Gordon model, the Mandelstam operator, which creates point-like topological solitons, is modifided in such a way as to account for the soliton structure. The resulting operator creates fermions with unitary topological charge and its application on the Fock vacuum produces a coherent state in which the mean field is given by the classical solitonic solution. By successive application of soliton creation operators, centered at different points, one obtains a coherent state in which the mean field is given by the sum of the individual mean fields. In the two-soliton state the mean interaction energy possesses a potential barrier behavior, displaying the repulsion between solitons in this model. Vve also consider a simplified non-topological soliton model, composed of one fermion confined in a scalar bosonic field. In the topological soliton modelas well as in the non-topological one, the variation of the norm of the two-soliton state, with the distance between their centers reveals a competition between the fermionic and bosonic statistics. In the small separation region the fermionic aspect prevails, making the norm go to zero. In the intermediate separation region, the norm exceeds unity due to the overlap of the bosonic quanta
Journal of Physics: Conference Series, 2015
The goal of this work is to establish a comparison between the very well studied 3 P0 model and a... more The goal of this work is to establish a comparison between the very well studied 3 P0 model and a bound-state corrected version, the C 3 P0 model, obtained from applying the Fock-Tani transformation to the 3 P0 model, in the context of the charmed-strange meson sector (DSJ meson). In particular, we shall calculate the decay amplitudes and decay rates of the Ds1(2460) + → D * + s π 0 and Ds1(2536) + → D * (2010) + K 0 , showing the differences between the two models.
International Journal of Modern Physics E-nuclear Physics, 2011
We investigate a double extension to the Standard Model (SM). A first extension introduces, via m... more We investigate a double extension to the Standard Model (SM). A first extension introduces, via minimal coupling, a massive Z ′ boson. This enlarged SM is coupled to a dark matter sector through the Stueckelberg mechanism by a A ′ boson. However, the A ′ boson does not interact directly with the SM fermions. In our study, we found that the A ′ is a massless photon-like particle in dark sector. Constraints on the mass for Z ′ and corrections to Z mass are obtained.
Glueball-glueball scattering in a constituent gluon model
Strange stars in the color flavor locked phase, as described by a generalization of the phenomeno... more Strange stars in the color flavor locked phase, as described by a generalization of the phenomenological MIT bag model proposed in the context of color superconductivity, are studied through a model motivated by the semiclassical solutions for hydrostatic equilibrium. Results show that within this framework it is possible to find ultracompact configurations situated between regular compact stars and black holes.
Neutron stars are the most compact objects in nature widely used in the study of dense matter phy... more Neutron stars are the most compact objects in nature widely used in the study of dense matter physics. In this work we investigate the structure of these stars, described by the Tolman-Openheimer-Volkof equations, using equations of state for both symmetric nuclear matter and quark matter. We obtain results for the mass-radius relation and then we compared ours results with the actual pulsar data recently observed PSR J1614-2230 with a mass 1.97pm0.04Modot1.97\pm 0.04\ M_{\odot}1.97pm0.04Modot.
Journal of Physics G: Nuclear and Particle Physics, 2021
International Journal of Modern Physics E
In this work we use a mapping technique to derive in the context of a constituent gluon model an ... more In this work we use a mapping technique to derive in the context of a constituent gluon model an effective Hamiltonian that involves explicit gluon degrees of freedom. We study glueballs with two gluons using the Fock-Tani formalism. In the present work we calculate the glueball-glueball potential, in the context of the constituent gluon model, with gluon interchange.
We investigate non-inertial effects on CP -violating processes using a model, based on the framew... more We investigate non-inertial effects on CP -violating processes using a model, based on the framework of quantum field theory in curved spacetimes, devised to account for the decay of accelerated particles. We show that the CP violation parameter for the decay of accelerated kaons into two pions decreases very slightly as very high accelerations are achieved, implying decreased asymmetry between matter and antimatter in this regime. We discuss the relationship between these results and cosmological processes surrounding matter-antimatter asymmetry and argue that, due to the connection between non-inertial and thermal phenomena established by the Unruh effect, this kind of computation may prove useful in furthering the understanding of thermodynamical effects in curved spacetimes.