Discrete R-symmetries and Anomaly Universality in Heterotic Orbifolds

We study discrete R-symmetries, which appear in 4D low energy effective field theory derived from hetetoric orbifold models. We derive the R-symmetries directly from geometrical symmetries of orbifolds. In particular, we obtain the corresponding R-charges by requiring that the couplings be invariant under these symmetries. This allows for a more general treatment than the explicit computations of correlation functions made previously by the authors, including models with discrete Wilson lines, and orbifold symmetries beyond plane-by-plane rotational invariance. Surprisingly, for the cases covered by earlier explicit computations, the R-charges differ from the previous result. We study the anomalies associated with these R-symmetries, and comment on the results.Comment: 21 pages, 2 figures. Minor changes, typos corrected. Matches JHEP published versio

A perfect match of MSSM-like orbifold and resolution models via anomalies

Compactification of the heterotic string on toroidal orbifolds is a promising set-up for the construction of realistic unified models of particle physics. The target space dynamics of such models, however, drives them slightly away from the orbifold point in moduli space. This resolves curvature singularities, but makes the string computations very difficult. On these smooth manifolds we have to rely on an effective supergravity approximation in the large volume limit. By comparing an orbifold example with its blow-up version, we try to transfer the computational power of the orbifold to the smooth manifold. Using local properties, we establish a perfect map of the the chiral spectra as well as the (local) anomalies of these models. A key element in this discussion is the Green-Schwarz anomaly polynomial. It allows us to identify those redefinitions of chiral fields and localized axions in the blow-up process which are relevant for the interactions (such as Yukawa-couplings) in the model on the smooth space.Comment: 2+35 pages, 1 figur

Facteurs Associes A L\'infertilite Masculine: Résultats d\'une série de 84 patients suivis à l\'Hôpital Général de Yaoundé.

In order to discriminate factors associated with male infertility in Cameroon , we selected from January 2001 to December 2006 , in the Gynecological Services of the General Hospital of Yaounde 84 infertile patients . The mean age was 38.21 years ±11 (range 25 – 50). Detailed exploration including laparoscopy was done for each female partner and this enabled us to eliminate some eventual disorders (endometriosis, tubo-peritoneal and ovarian sequelae of pelvic inflammatory diseases …) that could be a bias to our study population. Only husbands (without any known disease detrimental to their reproductive health) free from genital pathologies were recruited. Severe oligoasthenozoospermia was present in 51 cases ( 60.72%), followed by azoospermia, 15 cases ( 17. 86%), severe oligoasthenozoospermia associated with necrozoospermia, 13 cases (15. 47%), and a few cases of moderate oligospermia, 5 cases (5.95 %). No risk factor was found in 33 patients (39.28%) capable of altering the sperm. On the contrary we recorded a history of sexually transmitted infection due to Chlamydia trachomatis in 47 patients (55.95%), smoking in 13 patients (15.47%), alcoholism in 10 patients (11.90%), and exposure to pesticides in 2 patients (2.38%). Considering the risk factors found in our patients (within the limits of this study) and the fact that our environment is permanently filled with a “cocktail” of substances potentially detrimental to male fertility , emphasis should be placed on sensitization of our population and more particularly the youths who are vulnerable to sexually transmitted infections, smoking and alcoholism. On the other hand, the government should protect our environment from substances that are harmful to procreation through the concerted efforts of the different ministerial departments concerned.Dans le but de connaître les facteurs associés à l\'infertilité masculine au Cameroun , nous avons de Janvier 2001 à Décembre 2006 sélectionné dans les Services de Gynécologie de l\'Hôpital Général de Yaoundé, 84 patients infertiles d\'âge moyen 38,21 ± 11ans (27- 50), de niveau socio-économique moyen pour 78 d\'entre eux (92,85 %). Cinquante cinq (65, 47%) souffraient d\'une infertilité primaire depuis en moyenne 2,7 ans (1-5) , et 29 (34,53%) d\'une infertilité secondaire depuis en moyenne 3, 5 ans (2 - 6). Des explorations incluant la coelioscopie pratiquées à chaque fois chez les conjointes ont permis d\'éliminer d\'éventuelles pathologies (endométriose, séquelles tubo-péritonéales, voire ovariennes de maladies inflammatoires pelviennes …) susceptibles de biaiser notre population d\'étude. Seuls étaient recrutés les hommes n\'ayant aucune pathologie connue délétère pour la santé reproductive, et dont les partenaires ne présentaient pas de pathologie génitale. L\'oligo-asthénozoospermie sévère (OAS) a été retrouvée chez la majorité des patients , 51 cas (60,72 %), suivi de l\'azoospermie (AZO), 15 cas (17,86 %), l\'oligoasthénozoospermie sévère associée à une nécrozoospermie (0AS + N), 13 cas (15,47 %) , et dans une moindre mesure l\'oligospermie modérée (OM), 5 cas (5,95 %). Aucun facteur de risque susceptible d\'altérer le sperme n\'a été identifié chez 33 patients (39,28 %). En revanche nous avons identifié les antécédents d\'infections sexuelles à Chlamydia trachomatis chez 47 patients (55,95 %), le tabagisme chez 13 patients (15,47 %) , l\'alcoolisme chez 10 patients (11,90 %) , et l\'exposition aux pesticides chez 2 patients (2,38 %). Au regard des facteurs de risque retrouvés chez nos patients (sous réserve d\'une étude plus étendue), et de notre environnent en permanence inondé par un « cocktail de molécules» potentiellement nocives pour la fertilité masculine , un accent devra être mis sur la sensibilisation de nos populations et plus particulièrement la jeunesse actuellement vulnérable aux infections sexuellement transmissibles, au tabagisme et à l\'alcoolisme. Par ailleurs les pouvoirs publics doivent s\'investir à protéger l\'environnement des substances nocives pour la fertilité, à travers une approche intégrée des stratégies sectorielles des départements ministériels concernés. Keywords: Male infertility - Chlamydia - Smoking - Alcoholism - Pesticide.Clinics in Mother and Child Health Vol. 4 (1) 2007: pp. 665-67