Simplified R-Symmetry Breaking and Low-Scale Gauge Mediation

We argue that some of the difficulties in constructing realistic models of low-scale gauge mediation are artifacts of the narrow set of models that have been studied. In particular, much attention has been payed to the scenario in which the Goldstino superfield in an O'Raifeartaigh model is responsible for both supersymmetry breaking and R-symmetry breaking. In such models, the competing problems of generating sufficiently massive gauginos while preserving an acceptably light gravitino can be quite challenging. We show that by sharing the burdens of breaking supersymmetry and R-symmetry with a second field, these problems are easily solved even within the O'Raifeartaigh framework. We present explicit models realizing minimal gauge mediation with a gravitino mass in the eV range that are both calculable and falsifiable.Comment: 31 pages, 4 figures, references added, minor change

Assessment of Arthropod Ectoparasites associated with Poultry at Zoological Garden, Owerri, South-East, Nigeria

The characterization of arthropod ectoparasites infesting poultry at the Nekede Zoological Garden (NZG) in Owerri was conducted from May to July, 2017.  Arthropod sampling was done weekly by picking them from the bodies of their hosts after parting the feathers and/or by blowing of same. Lice and fleas were collected by applying concentrated ethyl alcohol-soaked cotton wool to anaesthetize the parasites. Mites were collected by scrapping the skin around their feet gently in order not to injure the bird. All the parasites collected were sorted and labeled based on sex, age and breed before they were transferred to the Laboratory of the Department of Zoology and Environmental Biology, Michael Okpara University of Agriculture, Umudike. Specimens were observed under a stereo-microscope, using x10 magnification power. Identification to generic and specific levels was done with the aid of pictures and taxonomic keys. Data were analyzed using descriptive statistics such as frequency and percentages. A total of 165 ectoparasites were collected belonging to five genera and five species. Irrespective of sex, age, breed, species or/and management level,  lice infestation was highest (84.24%), followed by fleas (10.30%) and the least was mites (5.45%). Prevalence of the ectoparasites infestation was higher in females (89.10%) than males (74.44%), adults (93.98%) than young (62.50%), and local (86.96%) than exotic (80.15%) breed. No ostrich was infested with lice and no female exotic poultry was infested with flea. &nbsp

Gluino Decay as a Probe of High Scale Supersymmetry Breaking

A supersymmetric standard model with heavier scalar supersymmetric particles has many attractive features. If the scalar mass scale is O(10 - 10^4) TeV, the standard model like Higgs boson with mass around 125 GeV, which is strongly favored by the LHC experiment, can be realized. However, in this scenario the scalar particles are too heavy to be produced at the LHC. In addition, if the scalar mass is much less than O(10^4) TeV, the lifetime of the gluino is too short to be measured. Therefore, it is hard to probe the scalar particles at a collider. However, a detailed study of the gluino decay reveals that two body decay of the gluino carries important information on the scalar scale. In this paper, we propose a test of this scenario by measuring the decay pattern of the gluino at the LHC.Comment: 29 pages, 9 figures; version published in JHE

Analysis of mutations causing familial hypercholesterolaemia in black South African patients of different ancestry

Background. Familial hypercholesterolaemia (FH) is usually caused by mutations in three genes (LDLR, APOB and PCSK9).Objective. To identify the spectrum of FH-causing mutations in black South African (SA) patients.Methods. DNA samples of 16 unrelated South African FH patients with elevated low-density lipoprotein cholesterol levels, tendon xanthomas and corneal arcus (3 clinically homozygous FH and 13 heterozygous FH) of ethnic African origin were screened for mutations in the LDLR (coding region, promoter and intron/exon boundaries), APOB (part of exon 26) and PCSK9 genes (exon 7), using high-resolution melting.Results. Eight LDLR mutations were identified, for an overall detection rate of 8/19 predicted FH-causing alleles (42.1%). The previously reported six base pair deletion p.(D47_G48del) was found in two patients, and two novel variants (c.1187-25T>C and c.1664T>G p.(L555R)) were found, both predicted to be pathogenic using in silico web-based predictive algorithms. No pathogenic variants in APOB or PCSK9 were found.Conclusions. These findings contribute to the knowledge of allelic heterogeneity in the spectrum of FH-causing mutations in black SA patients, signifying their ancestral diversity. The relatively low overall detection rate may reflect locus heterogeneity of the FH phenotype in black SA FH patients

Assessment of Common Chest X-ray Findings in Immuno-compromised Patients in Lagos Metropolis, Nigeria

Background: Retroviral diseases such as the Acquired Immuno-Deficiency Syndrome (AIDS), is characterized with immune suppression leading to opportunistic infections (OI). This immune deficiency predominantly involves the lungs, gastrointestinal tract and central nervous system. Purpose: To assess the prevalence of a variety of infections associated with immune compromised patients (ICPx)using chest radiographs.Methods: A retrospective study of 543 (44.75 % male and 55.25 % females) postero-anterior (PA) and the anteroposterior (AP) chest radiographs of HIV/AIDS patients for a period of 5 years (2008-2013), selected at random from the X-ray departments of 5 hospitals within Lagos Metropolis.Results: The result showed that about 395 (72.44 %) radiographs presented with various infectious patterns while148 (27.56 %) radiographs demonstrated normal radiographic patterns. Subjects with pulmonary tuberculosis (30.94 %) were presented with the most predominant opportunistic infections (OI), followed by pneumonia (17.12%), pleural effusion (12.89 %), kaposi’s sarcoma (8.66 %). Other conditions such as cardiomegaly, atelectasis and lung consolidations constituted 3.13 %.Conclusion: Most HIV/AIDS patients in Lagos metropolis presented with episodes of PTB as evidenced on the chest radiograph. Also, as important as the chest radiograph is in detecting lesions, some patients presented with normal chest x-ray findings despite a high suspicion of pulmonary disease

Patterns of Soft Masses from General Semi-Direct Gauge Mediation

We give a general formulation of semi-direct gauge mediation of supersymmetry breaking where the messengers interact with the hidden sector only through a weakly gauged group. Using this general formulation, we provide an explicit proof that the MSSM gaugino masses are vanishing to leading order in the gauge couplings. On the other hand, the MSSM sfermion masses have, generically, a non-vanishing leading contribution. We discuss how such a mechanism can successfully be combined with other mediation schemes which give tachyonic sfermions, such as sequestered anomaly mediation and some direct gauge mediation models.Comment: 26 pages, 5 figures; v2: refs added; v3: minor corrections, clarifications added, mainly in section

Phenomenological Aspects of Gauge Mediation with Sequestered Supersymmetry Breaking in light of Dark Matter Detection

In a recent work, a model of gauge mediation with sequestered supersymmetry (SUSY) breaking was proposed. In this model, the mass of the gravitino is O(100) GeV without causing the flavor-changing neutral-current problem. In contrast to traditional gauge mediation, the gravitino is not the lightest SUSY particle and the neutralino is the candidate of the dark matter. In this paper, we investigate phenomenological aspects of this model and discuss the possibility of the direct detection of the dark matter. In particular, we focus on the light neutralino case and find that the light-Higgsino scenario such as the focus point is interesting, taking account of the recent CDMS result.Comment: 17 pages, 8 figures; v2:references added, some corrections; v3:version accepted for publication in JHE

A Brief Review on Dark Matter Annihilation Explanation for e±e^\pm Excesses in Cosmic Ray

Recently data from PAMELA, ATIC, FERMI-LAT and HESS show that there are $e^{\pm}$ excesses in the cosmic ray energy spectrum. PAMELA observed excesses only in $e^+$, but not in anti-proton spectrum. ATIC, FERMI-LAT and HESS observed excesses in $e^++e^-$ spectrum, but the detailed shapes are different which requires future experimental observations to pin down the correct data set. Nevertheless a lot of efforts have been made to explain the observed $e^\pm$ excesses, and also why PAMELA only observed excesses in $e^+$ but not in anti-proton. In this brief review we discuss one of the most popular mechanisms to explain the data, the dark matter annihilation. It has long been known that about 23% of our universe is made of relic dark matter. If the relic dark matter was thermally produced, the annihilation rate is constrained resulting in the need of a large boost factor to explain the data. We will discuss in detail how a large boost factor can be obtained by the Sommerfeld and Briet-Wigner enhancement mechanisms. Some implications for particle physics model buildings will also be discussed.Comment: 22 pages, 6 figures. Several typoes corrected and some references added. Published in Mod. Phys. Lett. A, Vol. 24, No. 27 (2009) pp. 2139-216

(Extra)Ordinary Gauge/Anomaly Mediation

We study anomaly mediation models with gauge mediation effects from messengers which have a general renormalizable mass matrix with a supersymmetry-breaking spurion. Our models lead to a rich structure of supersymmetry breaking terms in the visible sector. We derive sum rules among the soft scalar masses for each generation. Our sum rules for the first and second generations are the same as those in general gauge mediation, but the sum rule for the third generation is different because of the top Yukawa coupling. We find the parameter space where the tachyonic slepton problem is solved. We also explore the case in which gauge mediation causes the anomalously small gaugino masses. Since anomaly mediation effects on the gaugino masses exist, we can obtain viable mass spectrum of the visible sector fields.Comment: 24 pages, 10 figure

A Clean Slepton Mixing Signal at the LHC

In supersymmetric scenarios where the scalar tau lepton is stable or long-lived, a search for a decay mode chi0 --> stau + mu at the LHC has a good sensitivity to the flavor mixing in the scalar lepton sector. We demonstrate that the sensitivities to the mixing angle at the level of sin(theta)=0.15 are possible with an integrated luminosity of 100fb^{-1} if the total production cross section of supersymmetric particles is of the order of 1pb. The sensitivity to the mixing parameter can be better than the experimental bound from the tau --> mu + gamma decay depending on model parameters.Comment: 7 pages, 2 figures, 1 table, the stau resolution corrected. version to appear in JHE