The rare decay t→cγt \to c \gamma in the General 2HDM type III

We consider the branching ratio for the process $t \to c \gamma$ in the context of the General Two Higgs Doublet Model type III. We find that taking into account reasonable values for the parameter $\tan \beta$ is possible to get values of this branching ratio up to orders of magnitude lying in the range of sensitivity of near future top quark experiments. For values of $B(t \to c \gamma) \sim 1-9 \times 10^{-5}$, values between 8-15 for $\tan \beta$ are allowed.Comment: 12 pages, 3 eps figures, RevTex

Quantized Faraday effect in (3+1)-dimensional and (2+1)-dimensional systems

We study Faraday rotation in the quantum relativistic limit. Starting from the photon self-energy in the presence of a constant magnetic field the rotation of the polarization vector of a plane electromagnetic wave which travel along the fermion-antifermion gas is studied. The connection between Faraday Effect and Quantum Hall Effect (QHE) is discussed. The Faraday Effect is also investigated for a massless relativistic (2D+1)-dimensional fermion system which is derived by using the compactification along the dimension parallel to the magnetic field. The Faraday angle shows a quantized behavior as Hall conductivity in two and three dimensions.Comment: 15 pages, 5 figure

Bounds for FCNC and the Pseudoscalar Higgs mass in the General Two Higgs Doublet Model type III using g−2g-2 muon factor

Current muon anomalous magnetic moment data have challenged the SM, and seems to open a window to new Physics. Since the difference between SM and experimental predictions is approximately $2.6\sigma$. In the framework of the General Two Higgs Doublet Model (2HDM), we calculate the muon anomalous magnetic moment to get lower and upper bounds for the Flavor Changing Yukawa couplings (FC) in the leptonic sector. We also obtain lower bounds for the mass of the Pseudoscalar Higgs ($m_{A^ 0}$, as a function of the parameters of the model.Comment: 9 pages, 5 figure

Effect of a Magnetic Field on the Electroweak Symmetry

We discuss the effect of a strong magnetic field in the behavior of the symmetry of an electrically neutral electroweak plasma. We analyze the case of a strong field and low temperatures as compared with the W rest energy. If the magnetic field is large enough, it is self-consistently maintained. Charged vector bosons play the most important role, leading only to a decrease of the symmetry breaking parameter, the symmetry restoration not being possible.Comment: Presented in the First International Workshop on Astronomy and Relativistic Astrophysics (IWARA 2003), Olinda, Brazi

Higgs boson decays in the littlest Higss model

We calculate the two body Higgs boson decays in the framework of the littlest Higgs model. The decay $H \to \gamma Z$ is computed at one loop level and, using previous results, we evaluate the branching fractions in the framework of the littlest Higgs model. A wide range of the space parameter of the model is considered and possible deviations from the standard model are explored.Comment: 13 pages, 5 figure

Fluctuations of work cost in optimal generation of correlations

We study the impact of work cost fluctuations on optimal protocols for the creation of correlations in quantum systems. We analyze several notions of work fluctuations to show that even in the simplest case of two free qubits, protocols that are optimal in their work cost (such as the one developed by Huber et al. [NJP 17, 065008 (2015)]) suffer work cost fluctuations that can be much larger than the work cost. We discuss the implications of this fact in the application of such protocols and suggest that, depending on the implementation, protocols that are sub-optimal in their work cost could beat optimal protocols in some scenarios. This highlights the importance of assessing the dynamics of work fluctuations in quantum thermodynamic protocols.Comment: 12 pages, 5 figures. RevTeX 4.1. V2: Updated with latest content and also match published versio

Effective Magnetic Moment of Neutrinos in Strong Magnetic Fields

We compute the effective magnetic moment of neutrino in the highly dense and strongly magnetized media. It is shown that this magnetic moment is generated due to the effective mass of neutrino and gives sufficiently high value of the magnetic moment in the core of neutron stars.Comment: 4 pages, 1 figur

Fundamental limitations to local energy extraction in quantum systems

We examine when it is possible to locally extract energy from a bipartite quantum system in the presence of strong coupling and entanglement, a task which is expected to be restricted by entanglement in the low-energy eigenstates. We fully characterize this distinct notion of "passivity" by finding necessary and sufficient conditions for such extraction to be impossible, using techniques from semidefinite programming. This is the first time in which such techniques are used in the context of energy extraction, which opens a way of exploring further kinds of passivity in quantum thermodynamics. We also significantly strengthen a previous result of Frey et al., by showing a physically relevant quantitative bound on the threshold temperature at which this passivity appears. Furthermore, we show how this no-go result also holds for thermal states in the thermodynamic limit, provided that the spatial correlations decay sufficiently fast, and we give numerical examples.Comment: 4.5+9 Pages, 4 Figures, Published versio

A note on double domination in graphs

Recently, Haynes, Hedetniemi and Henning published the book Topics in Domination in Graphs, which comprises 16 contributions that present advanced topics in graph domination, featuring open problems, modern techniques, and recent results. One of these contributions is the chapter Multiple Domination, by Hansberg and Volkmann, where they put into context all relevant research results on multiple domination that have been found up to 2020. In this note, we show how to improve some results on double domination that are included in the book

Dissipative Bohmian mechanics within the Caldirola-Kanai framework: A trajectory analysis of wave-packet dynamics in viscid media

Classical viscid media are quite common in our everyday life. However, we are not used to find such media in quantum mechanics, and much less to analyze their effects on the dynamics of quantum systems. In this regard, the Caldirola-Kanai time-dependent Hamiltonian constitutes an appealing model, accounting for friction without including environmental fluctuations (as it happens, for example, with quantum Brownian motion). Here, a Bohmian analysis of the associated friction dynamics is provided in order to understand how a hypothetical, purely quantum viscid medium would act on a wave packet from a (quantum) hydrodynamic viewpoint. To this purpose, a series of paradigmatic contexts have been chosen, such as the free particle, the motion under the action of a linear potential, the harmonic oscillator, or the superposition of two coherent wave packets. Apart from their analyticity, these examples illustrate interesting emerging behaviors, such as localization by "quantum freezing" or a particular type of quantum-classical correspondence. The reliability of the results analytically determined has been checked by means of numerical simulations, which has served to investigate other problems lacking of such analyticity (e.g., the coherent superpositions).Comment: 20 pages, 5 figure