117 research outputs found
Cynipid wasps inducing galls on plants of the genus Picris (Asteraceae) in Europe, with a description of a new species of Phanacis Foerster (Hymenoptera: Cynipidae) from the Iberian Peninsula.
The cynipid species (Hymenoptera, Cynipidae), which induceing galls on plants of the genus Picris (Asteraceae) in Europe, are revised. A key for the identification of adult wasps and galls of the three known species is provided. Phanacis helminthiae (De Stefani) is recorded from Sicily for the first time after since its description, and re-described with newly collected materials. The final instar larva of Phanacis caulicola is described and new biological data on the sex ratio and life-cycle of this species are given. A new species, Phanacis comosae nov. sp., is described from the Southwest portion of the Iberian Peninsula. The new species is closely allied related to P. caulicola and induces conspicuous galls in flower receptacles of Picris comosa
On the Quantitative Impact of the Schechter-Valle Theorem
We evaluate the Schechter-Valle (Black Box) theorem quantitatively by
considering the most general Lorentz invariant Lagrangian consisting of
point-like operators for neutrinoless double beta decay. It is well known that
the Black Box operators induce Majorana neutrino masses at four-loop level.
This warrants the statement that an observation of neutrinoless double beta
decay guarantees the Majorana nature of neutrinos. We calculate these
radiatively generated masses and find that they are many orders of magnitude
smaller than the observed neutrino masses and splittings. Thus, some lepton
number violating New Physics (which may at tree-level not be related to
neutrino masses) may induce Black Box operators which can explain an observed
rate of neutrinoless double beta decay. Although these operators guarantee
finite Majorana neutrino masses, the smallness of the Black Box contributions
implies that other neutrino mass terms (Dirac or Majorana) must exist. If
neutrino masses have a significant Majorana contribution then this will become
the dominant part of the Black Box operator. However, neutrinos might also be
predominantly Dirac particles, while other lepton number violating New Physics
dominates neutrinoless double beta decay. Translating an observed rate of
neutrinoless double beta decay into neutrino masses would then be completely
misleading. Although the principal statement of the Schechter-Valle theorem
remains valid, we conclude that the Black Box diagram itself generates
radiatively only mass terms which are many orders of magnitude too small to
explain neutrino masses. Therefore, other operators must give the leading
contributions to neutrino masses, which could be of Dirac or Majorana nature.Comment: 18 pages, 4 figures; v2: minor corrections, reference added, matches
journal version; v3: typo corrected, physics result and conclusions unchange
Goldstone Fermion Dark Matter
We propose that the fermionic superpartner of a weak-scale Goldstone boson
can be a natural WIMP candidate. The p-wave annihilation of this `Goldstone
fermion' into pairs of Goldstone bosons automatically generates the correct
relic abundance, whereas the XENON100 direct detection bounds are evaded due to
suppressed couplings to the Standard Model. Further, it is able to avoid
indirect detection constraints because the relevant s-wave annihilations are
small. The interactions of the Goldstone supermultiplet can induce non-standard
Higgs decays and novel collider phenomenology.Comment: 25 pages, 6 figures. References added, minor typos corrected.
Submitted to JHE
All solutions of the localization equations for N=2 quantum black hole entropy
We find the most general bosonic solution to the localization equations
describing the contributions to the quantum entropy of supersymmetric black
holes in four-dimensional N=2 supergravity coupled to n_v vector multiplets.
This requires the analysis of the BPS equations of the corresponding off-shell
supergravity (including fluctuations of the auxiliary fields) with AdS2 \times
S2 attractor boundary conditions. Our work completes and extends the results of
arXiv:1012.0265 that were obtained for the vector multiplet sector, to include
the fluctuations of all the fields of the off-shell supergravity. We find that,
when the auxiliary SU(2) gauge field strength vanishes, the most general
supersymmetric configuration preserving four supercharges is labelled by n_v+1
real parameters corresponding to the excitations of the conformal mode of the
graviton and the scalars of the n_v vector multiplets. In the general case, the
localization manifold is labelled by an additional SU(2) triplet of one-forms
and a scalar function.Comment: 27 page
Search for electromagnetic properties of the neutrinos at the LHC
Exclusive production of neutrinos via photon-photon fusion provides an
excellent opportunity to probe electromagnetic properties of the neutrinos at
the LHC. We explore the potential of processes pp-> p gamma gamma p -> p nu
anti-nu p and pp -> p gamma gamma p -> p nu anti-nu Z p to probe
neutrino-photon and neutrino-two photon couplings. We show that these reactions
provide more than seven orders of magnitude improvement in neutrino-two photon
couplings compared to LEP limits.Comment: 11 pages, 4 tables, New backgrounds have been adde
Exploring T and S parameters in Vector Meson Dominance Models of Strong Electroweak Symmetry Breaking
We revisit the electroweak precision tests for Higgsless models of strong
EWSB. We use the Vector Meson Dominance approach and express S and T via
couplings characterizing vector and axial spin-1 resonances of the strong
sector. These couplings are constrained by the elastic unitarity and by
requiring a good UV behavior of various formfactors. We pay particular
attention to the one-loop contribution of resonances to T (beyond the chiral
log), and to how it can improve the fit. We also make contact with the recent
studies of Conformal Technicolor. We explain why the second Weinberg sum rule
never converges in these models, and formulate a condition necessary for
preserving the custodial symmetry in the IR.Comment: 35 pages, 7 figures; v3: refs added, to appear in JHE
A Single Nucleotide Change Affects Fur-Dependent Regulation of sodB in H. pylori
Helicobacter pylori is a significant human pathogen that has adapted to survive the many stresses found within the gastric environment. Superoxide Dismutase (SodB) is an important factor that helps H. pylori combat oxidative stress. sodB was previously shown to be repressed by the Ferric Uptake Regulator (Fur) in the absence of iron (apo-Fur regulation) [1]. Herein, we show that apo regulation is not fully conserved among all strains of H. pylori. apo-Fur dependent changes in sodB expression are not observed under iron deplete conditions in H. pylori strains G27, HPAG1, or J99. However, Fur regulation of pfr and amiE occurs as expected. Comparative analysis of the Fur coding sequence between G27 and 26695 revealed a single amino acid difference, which was not responsible for the altered sodB regulation. Comparison of the sodB promoters from G27 and 26695 also revealed a single nucleotide difference within the predicted Fur binding site. Alteration of this nucleotide in G27 to that of 26695 restored apo-Fur dependent sodB regulation, indicating that a single base difference is at least partially responsible for the difference in sodB regulation observed among these H. pylori strains. Fur binding studies revealed that alteration of this single nucleotide in G27 increased the affinity of Fur for the sodB promoter. Additionally, the single base change in G27 enabled the sodB promoter to bind to apo-Fur with affinities similar to the 26695 sodB promoter. Taken together these data indicate that this nucleotide residue is important for direct apo-Fur binding to the sodB promoter
Neutrino mixing and leptonic CP violation from S 4 flavour and generalised CP symmetries
We consider a class of models of neutrino mixing with S4 lepton flavour symmetry combined with a generalised CP symmetry, which are broken to residual Z2 and Z2
7 HCP\u3bd symmetries in the charged lepton and neutrino sectors, respectively, HCP\u3bd being a remnant CP symmetry of the neutrino Majorana mass term. In this set-up the neutrino mixing angles and CP violation (CPV) phases of the neutrino mixing matrix depend on three real parameters \u2014 two angles and a phase. We classify all phenomenologically viable mixing patterns and derive predictions for the Dirac and Majorana CPV phases. Further, we use the results obtained on the neutrino mixing angles and leptonic CPV phases to derive predictions for the effective Majorana mass in neutrinoless double beta decay
Decay widths of the spin-2 partners of the X(3872)
We consider the X(3872) resonance as a JPC=1++ DDÂŻâ hadronic molecule. According to heavy quark spin symmetry, there will exist a partner with quantum numbers 2++, X2, which would be a DâDÂŻâ loosely bound state. The X2 is expected to decay dominantly into DDÂŻ, DDÂŻâ and DÂŻDâ in d-wave. In this work, we calculate the decay widths of the X2 resonance into the above channels, as well as those of its bottom partner, Xb2, the mass of which comes from assuming heavy flavor symmetry for the contact terms. We find partial widths of the X2 and Xb2 of the order of a few MeV. Finally, we also study the radiative X2âDDÂŻâÎł and Xb2âBÂŻBâÎł decays. These decay modes are more sensitive to the long-distance structure of the resonances and to the DDÂŻâ or BBÂŻâ final state interaction
- âŠ