Anapole moment of the lightest neutralino in the cMSSM

We study the anapole moment of the lightest neutralino in the constrained Minimal Supersymmetric Standard Model (cMSSM). The electromagnetic anapole is the only allowed electromagnetic form factor for Majorana fermions, such as the neutralino. Since the neutralino is the LSP in many versions of the MSSM and therefore a candidate for dark matter, its characterization through its electromagnetic properties is important both for particle physics and for cosmology. We perform a scan in the parameter space of the cMSSM and find that the anapole moment is different from zero albeit very small ($< 10^{-3}$ GeV$^{-2}$). Combined with experimental constraints like the Higgs mass and the DM relic density, the allowed region of parameter space lies within the reach of future direct DM searches. Thus, the anapole moment could be used as a complementary constraint when studying the parameter space of the cMSSM and other similar models.Comment: 22 pages, 13 figures. arXiv admin note: substantial text overlap with arXiv:1206.505

Empirical testing of Tsallis' Thermodynamics as a model for dark matter halos

We study a dark matter halo model from two points of view: the ``stellar polytrope'' (SP) model coming from Tsallis' thermodynamics, and the one coming from the Navarro-Frenk-White (NFW) paradigm. We make an appropriate comparison between both halo models and analyzing the relations between the global physical parameters of observed galactic disks, coming from a sample of actual galaxies, with the ones of the unobserved dark matter halos, we conclude that the SP model is favored over the NFW model in such a comparison.Comment: 5 pages, 1 figure, To appear in the Proceedings of X Mexican Workshop on Particles and Fields, Morelia Michoac\'an, M\'exico, November 7-12, 200

Entropy considerations in constraining the mSUGRA parameter space

We explore the use of two criteria to constraint the allowed parameter space in mSUGRA models. Both criteria are based in the calculation of the present density of neutralinos as dark matter in the Universe. The first one is the usual ``abundance'' criterion which is used to calculate the relic density after the ``freeze-out'' era. To compute the relic density we used the numerical public code micrOMEGAs. The second criterion applies the microcanonical definition of entropy to a weakly interacting and self-gravitating gas evaluating then the change in the entropy per particle of this gas between the ``freeze-out'' era and present day virialized structures. An ``entropy-consistency'' criterion emerges by comparing theoretical and empirical estimates of this entropy. The main objective of our work is to determine for which regions of the parameter space in the mSUGRA model are both criteria consistent with the 2$\sigma$ bounds according to WMAP for the relic density: $0.0945<\Omega_{CDM}h^2<0.1287$. As a first result, we found that for $A_0=0$, sgn$\mu=+$, small values of tan$\beta$ are not favored; only for tan$\beta\simeq50$ are both criteria significantly consistent.Comment: 5 pages, 1 figure. To appear in the Proceedings of X Mexican Workshop on Particles and Fields, Morelia Michoac\'an, M\'exico, November 7-12, 200

Engineering professors' conceptions on basic topics of electromagnetism in Mexico

Electromagnetism is one of the introductory physics subjects common to many engineering programs in Mexico and other countries. There are several studies about students’ misconceptions regarding the contents of electromagnetism courses but the information about teachers’ misconceptions which is one of the main factors that contribute to students’ misconceptions, is not very extensive. It is a fact that teachers, as well as students, have problems with the scientific knowledge of some concepts (Pardhan &amp; Bano, 2001). Since they are responsible for helping students to fully understand and give a proper meaning to these concepts, it is very important to find out what teachers know about these concepts, to generate teacher formation programs that help them in the improvement of their teaching activities. Moreover, most of the existing studies focus on identifying misconceptions about the properties of electric charges (Furió-Mas &amp; Guisasola Aranzabal, 2008), electric field, Gauss’s law, electric current (Hashish et al., 2020) and voltage, but none of them is centered around the basic concepts in electrostatics and the strong relations between them. This work is part of a qualitative research with a descriptive design and presents the results of a 2-tier instrument combined with a semi-structured interview, designed to identify the conceptions that in-service engineering teachers have about the concepts of electrostatic force, electric field, electric potential, and the relation between them, distinguishing between correct conceptions, misconceptions, and lack of knowledge. RESULTS Information about the teachers’ academic training and teaching experience will be presented, correlating this information to the conceptions that teachers have about the basic electrostatics concepts. Due to the academic training and teaching experience that in-service teachers have, predominance of misconceptions over lack of knowledge is expected. REFERENCES Furió-Mas, C., &amp; Guisasola Aranzabal, J. (2008). Dificultades de aprendizaje de los conceptos de carga y de campo eléctrico en estudiantes de bachillerato y universidad. Enseñanza de Las Ciencias. Revista de Investigación y Experiencias Didácticas, 16(1), 131–146. https://doi.org/10.5565/rev/ensciencias.4148. Hashish, A. H., Seyd-Darwish, I., &amp; Tit, N. (2020). Addressing Some Physical Misconceptions in Electrostatics of Freshman Engineering Students. International Journal for Innovation Education and Research, 8(2), 01–07. https://doi.org/10.31686/ijier.vol8.iss2.2161. Pardhan, H., &amp; Bano, Y. (2001). Science teachers’ alternate conceptions about direct-currents. International Journal of Science Education, 23(3), 301–318. https://doi.org/10.1080/095006901750066538

Magnus Expansion and Three-Neutrino Oscillations in Matter

We present a semi-analytical derivation of the survival probability of solar neutrinos in the three generation scheme, based on the Magnus approximation of the evolution operator of a three level system, and assuming a mass hierarchy among neutrino mass eigenstates. We have used an exponential profile for the solar electron density in our approximation. The different interesting density regions that appear throughout the propagation are analyzed. Finally, some comments on the allowed regions in the solar neutrino parameter space are addressed.Comment: RevTex4 style, 5 pages including 5 figures. Presented at Mexican School of Astrophysics 2002, Guanajuato, Mexico, 31 Jul - 7 Aug 2002. Final version to appear in the Proceedings of IX Mexican Workshop on Particles and Fields Physics Beyond the Standard Model, Colima Col. Mexico, November 17-22, 200