One-loop quantum corrections to cosmological scalar field potentials

We study the loop corrections to potentials of complex or coupled real scalar fields used in cosmology to account for dark energy, dark matter or dark fluid. We show that the SUGRA quintessence and dark matter scalar field potentials are stable against the quantum fluctuations, and we propose solutions to the instability of the potentials of coupled quintessence and dark fluid scalar fields. We also find that a coupling to fermions is very restricted, unless this coupling has a structure which already exists in the scalar field potential or which can be compensated by higher order corrections. Finally, we study the influence of the curvature and kinetic term corrections.Comment: 11 pages, 1 figure, accepted for publication in Phys. Rev.

QCD Corrections in two-Higgs-doublet extensions of the Standard Model with Minimal Flavor Violation

We present the QCD corrections to R_b and to the Delta B=1 effective Hamiltonian in models with a second Higgs field that couples to the quarks respecting the criterion of Minimal Flavor Violation, thus belonging either to the (1,2)_1/2 or to the (8,2)_1/2 representation of SU(3)xSU(2)xU(1). After the inclusion of the QCD corrections, the prediction for R_b becomes practically insensitive to the choice of renormalization scheme for the top mass, which for the type-I and type-II models translates in a more robust lower bound on tan(beta). The QCD-corrected determinations of Rb and BR(B->Xs gamma) are used to discuss the constraints on the couplings of a (colored) charged Higgs boson to top and bottom quarks.Comment: 19 pages, 7 figures. v2: version published in Phys. Rev. D, with additional reference and not

Investigating resonance detection methods in disc galaxies

Abstract. In this thesis the reliability of the Font-Beckman (FB) method in locating resonances in disc galaxies is investigated. In the first section of this thesis a general overview about galaxies is provided before moving on to the more specific topics. The literature review heavily focuses on resonance detection methods in disc galaxies, where a number them is used for comparisons with the FB method. The FB method attempts to locate resonances of a disc galaxy by finding zeros in its residual velocity map, which is a map of the galaxy’s non-circular line-of-sight velocity. These zeros are then counted and averaged radially; if a radius shows a clear peak in the number of these zeros, then it is taken as a FB resonance radius. The FB method was fully re-coded for the purposes of this thesis and is put to test in various ways, resulting in a lot of findings although only the main ones are mentioned in this abstract for brevity. The FB method’s reliability is tested via two approaches. The first approach is a simulation-based comparison, in which galaxies with theoretically-known resonances are simulated (using Wada simulations) and the FB method is applied to them. This allows for a direct comparison between FB and theoretical resonances. The main finding is that the FB method can reliably locate outer Lindblad resonances (success rate of 84%±16%), somewhat reliably locate inner Lindblad resonances (47%±27%) as well as inner 4:1 resonances (43%±16%), while it struggles to successfully locate the corotation resonances (17%±17%), which contradicts Font-Beckman’s claim that their method can reliably find corotation resonances. The simulated galaxies were coded such that some of the galactic parameters were adjustable, which allowed us to discover that the FB method works best when the inclination of the galaxy is around 45° as well as other minor findings. The second approach is based on a number of Monte Carlo simulations, where the results from the FB method’s application to real galaxies are used. A number of random resonances are generated and then compared to a number of RI (resonance indicator: a method that detects resonances) resonances. Simultaneously, the FB resonances are compared to the same RI resonances. If FB resonances correlate more closely with the RI resonances as compared to the random resonances with the RI resonances, then it is a positive sign for the reliability of the FB method. Naturally, this depends on how truly reliable the RI are themselves, which is beyond the scope of this study albeit worthy of further investigation. The RIs used are such methods as Tremaine-Weinberg, simulation-based, surface-brightness truncations, Buta-Zhang, rings, etc. In general, we find that the correlation between FB and RI resonances is weaker in barred galaxies. Furthermore, it is found that FB and RI resonances show the strongest correlation when rings are used as RI. Finally, it is concluded that although the FB method is somewhat successful, it is not perfect and further investigation is welcomed

Anomaly mediated SUSY breaking scenarios in the light of cosmology and in the dark (matter)

Anomaly mediation is a popular and well motivated supersymmetry breaking scenario. Different possible detailed realisations of this set-up are studied and actively searched for at colliders. Apart from limits coming from flavour, low energy physics and direct collider searches, these models are usually constrained by the requirement of reproducing the observations on dark matter density in the universe. We reanalyse these bounds and in particular we focus on the dark matter bounds both considering the standard cosmological model and alternative cosmological scenarios. These scenarios do not change the observable cosmology but relic dark matter density bounds strongly depend on them. We consider few benchmark points excluded by standard cosmology dark matter bounds and suggest that loosening the dark matter constraints is necessary in order to avoid a too strong (cosmological) model dependence in the limits that are obtained for these models. We also discuss briefly the implications for phenomenology and in particular at the Large Hadron Collider.Comment: 37 pages, 20 figures, 1 tabl

Response of free-living Nematodes to the quality of water and sediment at Bou Chrara Lagoon (Tunisia) during winter 2000

The Bou Ghrara lagoon, a stretch of water in southeastern Tunisia, has shown an alarming reduction of its fishery resources since 1993. In order to study the response of free-living nematodes to the water and sediment quality of this area, thirteen stations have been sampled. According to this study, the heavy metal, organic carbon and hydrocarbon content of sediments are key factors negatively influencing the density, biomass and diversity of the nematofauna

The Reasons of Death among Children and Adolescents in Lorestan Province, West of Iran, from 2007 to 2014

Background: The UNESCO, in the case of children's rights, has stressed that a child has a right to live in the best possible condition of health and hygiene as well as a safe and un-risky environment. Evaluation of the reasons for the death and mortality of children and adolescents can prevent similar deaths. The aim of this study was to evaluate the reasons of mortality among children and adolescents in Lorestan province.Methods: This cross-sectional study was conducted on children and adolescents (younger than 18 years old) in Lorestan province, west of Iran, in the period of 2007-2014 in Lorestan Legal Medicine Research Center. The demographic data of dead individuals, including age, sex and cause of death, were studied. The main reasons of death were classified in four main groups of trauma, asphyxia, poisoning, and miscellaneous causes (including physiological disease, infant insufficiency, cancer, and unknown cause). The data was analysed by the SPSS software (version 17). P value <0.05 was considered statistically significant.Results: In the period of 2007 to 2014, 1115 children died in Lorestan province, consisting of 634 (56.8%) boys and 481 (44.2%) girls. The highest mortality rate was observed in 15 to 18 year age group (n= 395, 35.4%). The most prevalent reasons of death were different types of trauma (65.3%), asphyxia (18%), miscellaneous causes (10.8%) and poisoning (5.8%).Conclusion: The outbreak of death and mortality in children and adolescents following trauma and accidents in our country seems significant in relation to the developing countries and few of the neighbouring countries. Considering the ability to carry out the preventative measures in this field, instantaneous policy making is needed in order to eliminate the present defects in the security provision to this group of society

The decay Bs -> mu+ mu-: updated SUSY constraints and prospects

We perform a study of the impact of the recently released limits on BR(Bs -> mu+ mu-) by LHCb and CMS on several SUSY models. We show that the obtained constraints can be superior to those which are derived from direct searches for SUSY particles in some scenarios, and the use of a double ratio of purely leptonic decays involving Bs -> mu+ mu- can further strengthen such constraints. We also discuss the experimental sensitivity and prospects for observation of Bs -> mu+ mu- during the sqrt(s)=7 TeV run of the LHC, and its potential implications.Comment: 30 pages, 21 figures. v2: Improved discussion of constraints from B -> tau nu, references adde

Brief review of the searches for the rare decays Bs0→μ+μ−B^0_s \rightarrow \mu^+ \mu^- and B0→μ+μ−B^0 \rightarrow \mu^+ \mu^-

The current experimental status of the searches for the very rare decays $B^0_s \rightarrow \mu^+ \mu^-$ and $B^0 \rightarrow \mu^+ \mu^-$ is discussed. These channels are highly sensitive to various extensions of the Standard Model, specially in the scalar and pseudoscalar sector. The recent, most sensitive measurements from the CDF, ATLAS, CMS and LHCb collaborations are discussed and the combined upper exclusion limit on the branching fractions determined by the LHC experiments is shown to be $4.2\times 10^{-9}$ for $B^0_s \rightarrow \mu^+ \mu^-$ and $0.8\times 10^{-9}$ for $B^0 \rightarrow \mu^+ \mu^-$. The implications of these tight bounds on a selected set of New Physics models is sketched.Comment: 20 pages, 15 figures, invited review for Modern Physics Letters