5,797 research outputs found
Majorana vs Pseudo-Dirac Neutrinos at the ILC
Neutrino masses could originate in seesaw models testable at colliders, with
light mediators and an approximate lepton number symmetry. The minimal model of
this type contains two quasi-degenerate Majorana fermions forming a
pseudo-Dirac pair. An important question is to what extent future colliders
will have sensitivity to the splitting between the Majorana components, since
this quantity signals the breaking of lepton number and is connected to the
light neutrino masses. We consider the production of these neutral heavy
leptons at the ILC, where their displaced decays provide a golden signal: a
forward-backward charge asymmetry, which depends crucially on the mass
splitting between the two Majorana components. We show that this observable can
constrain the mass splitting to values much lower than current bounds from
neutrinoless double beta decay and natural loop corrections.Comment: 16 pages, 5 figures; v2: Minor changes, version accepted for
publication in EPJ
Can SUSY relax LNV constraints coming from loop corrections to light neutrino masses on the low-scale Seesaw?
Heavy neutrinos from the Type-I Seesaw model can have a large mixing with
active states, motivating their search at collider experiments. However, loop
corrections to light neutrino masses constrain the heavy neutrinos to appear in
pseudo-Dirac pairs, leading to a potential suppression of lepton number
violating parameters.
In this work we perform a detailed review of a proposal to relax constraints
on lepton number violation by adding supersymmetry. We define the conditions
necessary to maximise the SUSY screening effect, with the objective of allowing
a larger mass splitting between low-scale heavy neutrino masses. We find that
the sole addition of SUSY does not guarantee a screening, and that favourable
cases have some degree of fine-tuning.Comment: 10 figure
Minimally non-local nucleon-nucleon potentials with chiral two-pion exchange including 's
We construct a coordinate-space chiral potential, including -isobar
intermediate states in its two-pion-exchange component. The contact
interactions entering at next-to-leading and next-to-next-to-next-to-leading
orders ( and , respectively, denoting generically the low
momentum scale) are rearranged by Fierz transformations to yield terms at most
quadratic in the relative momentum operator of the two nucleons. The low-energy
constants multiplying these contact interactions are fitted to the 2013 Granada
database, consisting of 2309 and 2982 data (including, respectively,
148 and 218 normalizations) in the laboratory-energy range 0--300 MeV. For the
total 5291 and data in this range, we obtain a /datum of
roughly 1.3 for a set of three models characterized by long- and short-range
cutoffs, and respectively, ranging from fm down to fm. The long-range
(short-range) cutoff regularizes the one- and two-pion exchange (contact) part
of the potential.Comment: 32 pages, 19 figures, accepted for publication as a Regular Article
in Physical Review
Neutron Fermi Liquids under the presence of a strong magnetic field with effective nuclear forces
Landau's Fermi Liquid parameters are calculated for non-superfluid pure
neutron matter in the presence of a strong magnetic field at zero temperature.
The particle-hole interactions in the system, where a net magnetization may be
present, are characterized by these parameters in the framework of a multipolar
formalism. We use either zero- or finite-range effective nuclear forces to
describe the nuclear interaction. Using the obtained Fermi Liquid parameters,
the effect of a strong magnetic field on some bulk magnitudes such as
isothermal compressibility and spin susceptibility is also investigated.Comment: 20 pages, 10 figure
Angiogenesis in the Gonadal Capillary Network of the Chick Embryo
Seventy-one chick embryos of both sexes at the 35 Hamburger and Hamilton (H-H) developmental stage were processed for scanning electron microscopy of vascular corrosion casts and of critical point dried specimens, as well as transmission electron- and light microscopy, in order to study the angiogenic structures. The gonadal subepithelial capillary network was located at the level of the tunica albuginea under the covering epithelium. The casts showed a densely-meshed capillary network and numerous sprouting (nodular protrusions or capillary sprouts) and non-sprouting (enlarged vessels and angiogenic holes) angiogenic structures that were randomly distributed and mixed. Four types of angio-genic holes were encountered in the casts: primary (diameter \u3c 2.5 ÎŒm), secondary (diameter \u3e 2.5 ÎŒm), tertiary (variable diameter and circular narrowings on one side), and open angiogenic holes. We suggest that the different morphologies reflect evolution of these holes. Furthermore, the open angiogenic hole would probably either form nodular protrusions at its open ends, which tend to join with other nodular protrusions and neighboring capillaries and form new vessels; or there would be fusion with two or more neighboring open holes. Correlative critical point dried sections showed fenestrations in the capillary walls and transcapillary pillars that corresponded to the angiogenic holes found in the casts. Ultrathin sections of the vessels presented typical characteristics of growing endothelium: large nuclei with loosely textured chromatin, abundant cytoplasm rich in cell organelles and intraluminal endothelial processes
Phase retrieval from experimental far-field intensity data
Contiene: FĂłrmulas y 5 ilustraciones.We demonstrate the reconstruction of real and positive objects from experimental far-field intensity measurements
by means of two phase-retrieval algorithms. Both the iterative Fourier transform and the simulated annealing
algorithms are used, and an analysis is made of the advantages and disadvantages of each of these procedures and
also of combinations of both methods. The objects tested either were binary or had many gray levels. We worked with data with a considerable amount of experimental noise, and in addition we recognized the importance of taking into account the nonrandom distortions produced by the detecting devices, which can critically bias the results toward erroneous estimates of the objects. Noisy data, however, can create ambiguities in the reconstructions, and
hence additional information may be needed to overcome this disadvantage.Supported by the Comision Interministerial
de Ciencia y Tecnologia of Spain under grant pbO278. M. J. PĂ©rez-Ilzarbe acknowledges a grant from Ministerio de Educaci6n y Ciencia - This paper was published in Journal of the Optical Society of America A, and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://www.opticsinfobase.org/abstract.cfm?URI=josaa-7-3-434. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law.Peer reviewe
Deciding Entailments in Inductive Separation Logic with Tree Automata
Separation Logic (SL) with inductive definitions is a natural formalism for
specifying complex recursive data structures, used in compositional
verification of programs manipulating such structures. The key ingredient of
any automated verification procedure based on SL is the decidability of the
entailment problem. In this work, we reduce the entailment problem for a
non-trivial subset of SL describing trees (and beyond) to the language
inclusion of tree automata (TA). Our reduction provides tight complexity bounds
for the problem and shows that entailment in our fragment is EXPTIME-complete.
For practical purposes, we leverage from recent advances in automata theory,
such as inclusion checking for non-deterministic TA avoiding explicit
determinization. We implemented our method and present promising preliminary
experimental results
Vascular Architecture of the Lactating and Non-Lactating Teat of the Bitch: A Scanning Electron- and Light Microscope Study
Tissues from fourteen mammary glands of eight bitches were prepared for scanning electron microscopy of vascular corrosion casts and for histology to study the vasculature of the lactating and non-lactating teats. The densely-meshed mammary dermal capillary network formed ridges and troughs. The teat ducts were vascularized by a relatively densely-meshed capillary network which drained into veins longitudinally oriented to the ducts. Between eight and fifteen teat duct openings were seen on the tip of the teat, that were sometimes divided by a septum. The inner vascularization of the teat showed that the main papillary arteries divided into undulating secondary papillary arteries which presented numerous semi-constrictions and loops. Their structure may help during erection of the teat. Arteriovenous anastomoses found at different points may participate in blood flow maintenance during suckling, heat regulation and teat erection. Veins freely anastomosed and ran longitudinally to the axis of the teat. They exhibited numerous bicuspid valves. In non-lactating teats, vessels showed the same main architecture and characteristics mentioned above, although these were considerably less marked. The structure of the vascular elements in the teat of the bitch could favor blood flow during suckling and suggest that vessels adapt to the physiological situation
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