QCD Corrections to K-Kbar Mixing in R-symmetric Supersymmetric Models

The leading-log QCD corrections to K-Kbar mixing in R-symmetric supersymmetric models are computed using effective field theory techniques. The spectrum topology where the gluino is significantly heavier than the squarks is motivated and focused on. It is found that, like in the MSSM, QCD corrections can tighten the kaon mass difference bound by roughly a factor of three. CP violation is also briefly considered, where QCD corrections can constrain phases to be as much as a factor of ten smaller than the uncorrected value.Comment: 11 pages, 11 pdf-figures; updated acknowledgments and references, clarified relationship to Ref[17], clarified CP-violation sectio

Mineral reaction kinetics constrain the length scale of rock matrix diffusion

Mass transport by aqueous fluids is a dynamic process in shallow crustal systems, redistributing nutrients as well as contaminants. Rock matrix diffusion into fractures (void space) within crystalline rock has been postulated to play an important role in the transient storage of solutes. The reacted volume of host rock involved, however, will be controlled by fluid-rock reactions. Here we present the results of a study which focusses on defining the length scale over which rock matrix diffusion operates within crystalline rock over timescales that are relevant to safety assessment of radioactive and other long-lived wastes. Through detailed chemical and structural analysis of natural specimens sampled at depth from an active system (Toki Granite, Japan), we show that, contrary to commonly proposed models, the length scale of rock matrix diffusion may be extremely small, on the order of centimetres, even over timescales of millions of years. This implies that in many cases the importance of rock matrix diffusion will be minimal. Additional analyses of a contrasting crystalline rock system (Carnmenellis Granite, UK) corroborate these results

Supersymmetry with a Chargino NLSP and Gravitino LSP

We demonstrate that the lightest chargino can be lighter than the lightest neutralino in supersymmetric models with Dirac gaugino masses as well as within a curious parameter region of the MSSM. Given also a light gravitino, such as from low scale supersymmetry breaking, this mass hierarchy leads to an unusual signal where every superpartner cascades down to a chargino that decays into an on-shell W and a gravitino, possibly with a macroscopic chargino track. We clearly identify the region of parameters where this signal can occur. We find it is generic in the context of the R-symmetric supersymmetric standard model, whereas it essentially only occurs in the MSSM when sign(M1) is not equal to sign(M2) = sign(\mu) and tan(beta) is small. We briefly comment on the search strategies for this signal at the LHC.Comment: 27 pages and 16 figure

Signature of small rings in the Raman spectra of normal and compressed amorphous silica: A combined classical and ab initio study

We calculate the parallel (VV) and perpendicular (VH) polarized Raman spectra of amorphous silica. Model SiO2 glasses, uncompressed and compressed, were generated by a combination of classical and ab initio molecular-dynamics simulations and their dynamical matrices were computed within the framework of the density functional theory. The Raman scattering intensities were determined using the bond-polarizability model and a good agreement with experimental spectra was found. We confirm that the modes associated to the fourfold and threefold rings produce most of the Raman intensity of the D1 and D2 peaks, respectively, in the VV Raman spectra. Modifications of the Raman spectra upon compression are found to be in agreement with experimental data. We show that the modes associated to the fourfold rings still exist upon compression but do not produce a strong Raman intensity, whereas the ones associated to the threefold rings do. This result strongly suggests that the area under the D1 and D2 peaks is not directly proportional to the concentration of small rings in amorphous SiO2.Comment: 21 pages, 8 figures. Phys. Rev. B, in pres

Birthing practices of traditional birth attendants in South Asia in the context of training programmes

Traditional Birth Attendants (TBA) training has been an important component of public health policy interventions to improve maternal and child health in developing countries since the 1970s. More recently, since the 1990s, the TBA training strategy has been increasingly seen as irrelevant, ineffective or, on the whole, a failure due to evidence that the maternal mortality rate (MMR) in developing countries had not reduced. Although, worldwide data show that, by choice or out of necessity, 47 percent of births in the developing world are assisted by TBAs and/or family members, funding for TBA training has been reduced and moved to providing skilled birth attendants for all births. Any shift in policy needs to be supported by appropriate evidence on TBA roles in providing maternal and infant health care service and effectiveness of the training programmes. This article reviews literature on the characteristics and role of TBAs in South Asia with an emphasis on India. The aim was to assess the contribution of TBAs in providing maternal and infant health care service at different stages of pregnancy and after-delivery and birthing practices adopted in home births. The review of role revealed that apart from TBAs, there are various other people in the community also involved in making decisions about the welfare and health of the birthing mother and new born baby. However, TBAs have changing, localised but nonetheless significant roles in delivery, postnatal and infant care in India. Certain traditional birthing practices such as bathing babies immediately after birth, not weighing babies after birth and not feeding with colostrum are adopted in home births as well as health institutions in India. There is therefore a thin precarious balance between the application of biomedical and traditional knowledge. Customary rituals and perceptions essentially affect practices in home and institutional births and hence training of TBAs need to be implemented in conjunction with community awareness programmes

R-symmetric gauge mediation

We present a version of Gauge Mediated Supersymmetry Breaking which preserves an R-symmetry - the gauginos are Dirac particles, the A-terms are zero, and there are four Higgs doublets. This offers an alternative way for gauginos to acquire mass in the supersymmetry-breaking models of Intriligator, Seiberg, and Shih. We investigate the possibility of using R-symmetric gauge mediation to realize the spectrum and large sfermion mixing of the model of Kribs, Poppitz, and Weiner.Comment: 26+ pages, 3 figures, BIBTEX; v2 published version: references added, paragraph on spectrum running removed, section added on adjoint scalar masses, clarification of the meaning of Table 3 adde

Dark Matter with Dirac and Majorana Gaugino Masses

We consider the minimal supersymmetric extension of the Standard Model allowing both Dirac and Majorana gauginos. The Dirac masses are obtained by pairing up extra chiral multiplets: a singlet S for U(1)_Y, a triplet T for SU(2) and an octet O for SU(3) with the respective gauginos. The electroweak symmetry breaking sector is modified by the couplings of the new fields S and T to the Higgs doublets. We discuss two limits: i) both the adjoint scalars are decoupled with the main effect being the modification of the Higgs quartic coupling; ii) the singlet remaining light, and due to its direct coupling to sfermions, providing a new contribution to the soft masses and inducing new decay/production channels. We discuss the LSP in this scenario; after mentioning the possibility that it may be a Dirac gravitino, we focus on the case where it is identified with the lightest neutralino, and exhibit particular values of the parameter space where the relic density is in agreement with WMAP data. This is illustrated for different scenarios where the LSP is either a bino (in which case it can be a Dirac fermion) or bino-higgsino/wino mixtures. We also point out in each case the peculiarity of the model with respect to dark matter detection experiments.Comment: 43 pages, 5 figures; one reference added. Corresponds to published version in JCA

Revised decay properties of the key 93-keV resonance in the Mg 25 (p,γ) reaction and its influence on the MgAl cycle in astrophysical environments

The γ-decay properties of an excited state in Al26 at 6398.3(8) keV have been reexamined using the B11+O16 fusion-evaporation reaction. This level represents a key 93.1(8)-keV resonance in the Mg25+p system and its relative branching to the Al26 ground state, f0, has been determined to be 0.76±0.03 (stat.) ±0.10 (syst.). This is a significantly higher value than the most recent evaluation and implies a considerable increase in the production of cosmic γ rays from Al26 radioactivity

Database of diazotrophs in global ocean: abundance, biomass and nitrogen fixation rates

Marine N2 fixing microorganisms, termed diazotrophs, are a key functional group in marine pelagic ecosystems. The biological fixation of dinitrogen (N2) to bioavailable nitrogen provides an important new source of nitrogen for pelagic marine ecosystems and influences primary productivity and organic matter export to the deep ocean. As one of a series of efforts to collect biomass and rates specific to different phytoplankton functional groups, we have constructed a database on diazotrophic organisms in the global pelagic upper ocean by compiling about 12 000 direct field measurements of cyanobacterial diazotroph abundances (based on microscopic cell counts or qPCR assays targeting the nifH genes) and N2 fixation rates. Biomass conversion factors are estimated based on cell sizes to convert abundance data to diazotrophic biomass. The database is limited spatially, lacking large regions of the ocean especially in the Indian Ocean. The data are approximately log-normal distributed, and large variances exist in most sub-databases with non-zero values differing 5 to 8 orders of magnitude. Reporting the geometric mean and the range of one geometric standard error below and above the geometric mean, the pelagic N2 fixation rate in the global ocean is estimated to be 62 (52–73) Tg N yr?1 and the pelagic diazotrophic biomass in the global ocean is estimated to be 2.1 (1.4–3.1) Tg C from cell counts and to 89 (43–150) Tg C from nifH-based abundances. Reporting the arithmetic mean and one standard error instead, these three global estimates are 140 ± 9.2 Tg N yr?1, 18 ± 1.8 Tg C and 590 ± 70 Tg C, respectively. Uncertainties related to biomass conversion factors can change the estimate of geometric mean pelagic diazotrophic biomass in the global ocean by about ±70%. It was recently established that the most commonly applied method used to measure N2 fixation has underestimated the true rates. As a result, one can expect that future rate measurements will shift the mean N2 fixation rate upward and may result in significantly higher estimates for the global N2 fixation. The evolving database can nevertheless be used to study spatial and temporal distributions and variations of marine N2 fixation, to validate geochemical estimates and to parameterize and validate biogeochemical models, keeping in mind that future rate measurements may rise in the future. The database is stored in PANGAEA (doi:10.1594/PANGAEA.774851)