3,666 research outputs found
Heavy neutrinos with dynamic jet vetoes: multilepton searches at √s=14, 27, and 100 TeV
No full textHeavy neutrinos (N) remain one of most promising explanations for the ori-gin of neutrinos' tiny masses and large mixing angles. In light of broad advances in un-derstanding and modeling of hadron collisions at large momentum transfers, we revisit the long-standard search strategy for heavy N decaying to multiple charged leptons (), pp NX 3X. For electroweak and TeV-scale N, we propose a qualitatively new collider analysis premised on a dynamic jet veto and discriminating, on an event-by-event basis, according to the relative amount of hadronic and leptonic activity. We report that the sensitivity to heavy neutrinos at the CERN Large Hadron Collider (LHC) can be improved by roughly an order of magnitude at both L = 300 fb(-1) and 3 ab(-1). At =14 TeV with L=3 ab(-1), we find active-sterile mixing as small as |V-N|(2)=10(-2)(10(-3))[5x10(-4)] can be probed at 95% CL for heavy Dirac neutrinos masses m(N) less than or similar to 1200 (300) [200] GeV, well beyond the present |V-N|(2)less than or similar to 10(-3)-10(-1) constraints for such heavy states set by indirect searches and precision measurements. The improvement holds also for Majorana N, and is largely independent of whether charged lepton flavor is conserved or violated. The analysis, built almost entirely from inclusive, transverse observables, is designed to be robust across increasing collider energies, and hence serves as a basis for searches at future colliders: with L=15ab(-1) at 27 TeV,onecanprobemixingbelow |V-N|(2)=10(-2)(10(-3))[2x10(-4)] for m(N) less than or similar to 3500 (700) [200] GeV. At a hypothetical 100 TeV pp collider with L=30ab(-1), one can probe mixing down to 9 x 10(-5) for m(N) less than or similar to 200 GeV, below 10(-3) for m(N) less than or similar to 4 TeV, and below 10(-2) for m(N) less than or similar to 15 TeV. We anticipate these results can be further improved with detector-specific tuning and application of multi-variant / machines learning techniques. To facilitate such investigations, we make publicly available Monte Carlo libraries needed for the precision computations/simulations used in our study
Safe jet vetoes
No full textCentral jet vetoes are powerful tools for reducing QCD background in measurements and searches for electroweak and colorless, new physics processes in hadron collisions. In this letter, we report the key findings of a new philosophy to designing searches for such phenomena at hadron colliders, one designed and centered around a dynamical jet veto instead of a static veto applied independently of other selection criteria. Specifically, we investigate the theoretical and phenomenological consequences of setting the jet veto scale to the transverse momentum (p(T)) of the leading charged lepton L in multi-lepton processes on an event-by-event basis. We consider the case of a TeV-scale heavy neutrino N decaying to the trilepton final state and find the following: (i) Perturbative uncertainties associated with the veto greatly reduce due to tying the veto scale to the hard process scale. (ii) The signal efficiency for passing the veto jumps to greater than or similar to 95% and exhibits little-to-no dependence on the neutrino mass scale. (iii) Top quark and "fake" lepton rejection capabilities also improve compared to only vetoing heavy flavor-tagged jets above a fixed p(T). This results in an increased sensitivity to active-sterile neutrino mixing by approximately an order of magnitude over the LHC's lifetime. For a Dirac neutrino with mass m(N) = 150-1000 GeV and the representative active-sterile mixing hypothesis vertical bar V-e4 vertical bar = vertical bar V-tau(4)vertical bar with vertical bar V-mu 4 vertical bar = 0, we find that LHC experiments can probe vertical bar V-e4 vertical bar(2), vertical bar V-tau 4 vertical bar(2) less than or similar to 6 x 10(-4) -8 x 10(-3), surpassing the global upper limit for m(N) < 450 GeV, with L =3 ab(-1) of data at root s = 14 TeV. Due to the color structures of the heavy N production mechanisms considered, we argue that our results hold broadly for other color-singlet processes. (C) 2018 The Authors. Published by Elsevier B.V
Ultrastructural changes of the midgut cells during overwintering of Meta menardi (Latreille 1804) (Araneae, Tetragnathidae) in natural habitats
No full textMeta menardi je troglofilna vrsta. Večino življenjskega cikla preživi v podzemeljskih habitatih. V svojem življenjskem ciklu nima programiranega prezimovanja, kar pomeni, da se pozimi priložnostno prehranjuje. Ob nedostopnosti plena in posledičnem stradanju v celicah potečejo procesi, značilni za vrste s programiranim prezimovanjem, ki se pozimi ne prehranjujejo. S svetlobno in transmisijsko elektronsko mikroskopijo smo proučili strukturo in ultrastrukturo divertiklov srednjega črevesa M. menardi med prezimovanjem v naravnih habitatih. Samce in samice M. menardi smo nabrali v različnih obdobjih prezimovanja – na začetku (november), na sredi (januar) in ob koncu prezimovanja (marec). Zanimale so nas spremembe v strukturi in ultrastrukturi pri obeh spolih, spreminjanje količine založnih snovi, značilnosti sferitov in pojav avtofagnih struktur, ki odražajo trajanje stradanja med prezimovanjem. Epitel divertiklov srednjega črevesa je bil zgrajen iz prebavnih, sekrecijskih in založnih celic. V strukturi in ultrastrukturi med spoloma ni bilo razlik. Med prezimovanjem so se v epitelnih celicah divertiklov pojavile spremembe, značilne za stradanje. Količina založnih snovi (glikogena in lipidov) se je zmanjšala. Sferiti so imeli med prezimovanjem vse več elektronsko svetlejših, izpraznjenih plasti. Število avtofagnih struktur, stopnja vakuolizacije citoplazme in poraba materiala iz vakuol so se povečali. Ultrastrukturne značilnosti, ki so odraz stradanja med prezimovanjem, so pri M. menardi posledica pomanjkanja in nedostopnosti plena, ki prezimuje v jamah. Nutriente in energijo za vzdrževanje različnih fizioloških procesov, potrebnih za preživetje med stradanjem, so pajki pridobivali s porabo energijsko bogatih založnih snovi, iz mineralnih in organskih sestavin sferitov, z razgradnjo celičnih sestavin v procesu avtofagije in intenzivne vakuolizacije ter priložnostno s prebavo ujetega plena. Ob koncu prezimovanja so se pri eni samici v tkivu z značilnostmi stradanja pojavile velike, elektronsko temne prebavne vakuole, z lipidnimi kapljami, kar je dokaz, da je samica ob koncu prezimovanja ujela plen. Ujetje plena je najverjetneje sovpadlo z zaključkom prezimovanja nekaterih nevretenčarjev v jami in posledično migracijo določenega plena iz jame.Meta menardi is a troglophile species. They spend most of their life cycle in hypogean habitats. There is no programmed overwintering in the life cycle of M. menardi, which means that they can occasionally feed during the wintertime. In the absence of prey, the spiders starve and in the epithelial cells of the midgut diverticula appear processes, typical of species with programmed overwintering, i. e., programmed starvation in winter. Using the light and transmission electron microscopy we studied structure and ultrastructure of the epithelial cells of midgut diverticula in M. menardi during overwintering in natural habitats. Males and females were collected in different time frames of overwintering – at the beginning (November), in the middle (January) and at the end (March) of overwintering. The aim of this study was to investigate structural and ultrastructural changes in both sexes, changes in quantity of reserve substances, ultrastructure of spherites and occurrence of autophagic structures, which progressive changes reflect the duration of starvation during overwintering. The midgut epithelium was constituted of digestive, secretory and reserve cells. There were no differences in the structure and ultrastructure in the midgut diverticula epithelium between the sexes. During overwintering, in the midgut diverticula epithelial cells, changes typical of starvation occurred. The quantities of reserve substances (glycogen and lipids) diminished. During overwintering spherites became gradually more electron lucent, since the concentric layers were exploited. The abundance of the autophagic structures, the degree of cytoplasm vacuolization and the use of the cytoplasmic material increased. Ultrastructural features of the M. menardi midgut epithelium reflected processes typical of starvation during overwintering. These features are the consequence of absence and unavailability of prey in caves during the wintertime. All M. menardi obtained nutrients and energy for maintenance of different physiological processes, indispensable for survival during the starvation period, from different sources. Nutrients and energy were provided from lipid and glycogen reserves, mineral and organic compounds from spherites and degradation of cytoplasmic components in the processes of autophagy and intensive vacuolization. Occasionally, some individuals captured and digested prey. Consequently, at the end of overwintering, in a female at the same time characteristics typical of starvation, and large, electron dense digestive vacuoles with lipid droplets occurred. This case of prey capture probably coincided with the end of overwintering of some invertebrates in caves, and their migration out of the cave
Zwei Berichte über die Entwicklung des Martyrerkultus in Manastirine
No full textManastirine is an ancient funerary complex north of Salona and near its episcopal centre. The most prestigious martyrs of Salona (those of the persecution of Diocletian) were buried there. After the fall of Salona (about 620), however, their relics were taken to Rome on the initiative of a Dalmatian pope. There they were installed in a specially built chapel in the Lateran, which was decorated with their portraits. It was very natural for the bishops of the fourth century and of the beginning of the fifth century to be buried near the saints, not far from their cathedral, as well as a large number of distinguished or more humble Christians. The excavation is an old one. It is very well known because of the debate it aroused at the end of the nineteenth century and the beginning of the twentieth century (it contradicted local legends), because of the personality of the principal excavator, Mgr Bulić, and because of the repercussions of the publication by the Austrian archaeologist Egger, who reconstructed the history of the site in 1926. A Franco-Croatian team undertook the task of reinterpreting the site, with supplementary excavation, from 1985 to 1999. It has just published a large volume giving the detail of its re-examination, which on several vital matters contradicts the scheme of development and the chronology proposed by Egger. There are two detailed reports which discuss a number of key points. J. Dresken-Weiland is the author of the volume of the Repertorium christlicher Sarkophagen which has reviewed the Adriatic sarcophagi carrying decoration (in the broadest sense), and she has devoted her thèse d’habilitation (as yet unpublished) to inhumation in sarcophagi, relying largely on the examples from Salona. As a result she sticks to the absolute and relative chronology of the burials and of the funerary monuments built round the tomb of the martyrs. B. Brenk is the well-known historian of the art of the late antique and early Byzantine period. He is more interested in the cult of the martyrs. He is surprised that burial-place of the martyrs, although in the open air, kept an almost private character in spite of the inhumation of bishops, members of the clergy and of leading citizens up to the 430s – a late date for the construction of a proper church. Both authors discuss the relationships between pagans and Christians in the light of the origin of the cemetery, the date and use of the areae, and of the ‘chapels’ (which are in fact mausolea with apses, without tombs of martyrs, and without liturgical fittings). In conclusion N. Duval makes a number of factual points. Concerning B. Brenk’s essay, he notes the persistence of a number of examples of the traditional interpretation, which have sometimes been contradicted by the facts of the recent analysis. He also defends the method followed, which has set bounds to comparisons which should be made with the monuments of Salona.
Nous avons reçu deux longs comptes rendus du même volume de collègues particulièrement qualifiés pour en juger. Puisque l’angle d’examen choisi n’est pas le même, nous publions ces deux textes, l’un à la suite de l’autre, comme il nous est arrivé de le faire mais dans des numéros différents. Noël Duval, qui a dirigé la rédaction française de cet ouvrage collectif, a ajouté quelques notes pour dissiper des incertitudes dont témoigne parfois cette double lecture
Nonlinear fluid equations for fully toroidal electromagnetic waves for the core tokamak plasma
No full textThe rather general set of fluid equations with full curvature effects (Shukla and Weiland, Phys. Rev. A 40, 341 ( 1989)) has been modified to apply to the core and generalized to include also microtearing modes
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The Newsletter of the International Fission-Track Community
No full textEditor's Notes -- Summary of ICOG8 Events / by Paul Fitzgerald -- Fission-Track Standards Committee / by Casey Ravenhurst -- Corning Glass Dosimeter Update / by Barry Kohn -- Fission-Track Bibliography Available / by Dennis Arne -- Short Tracks: News -- International Workshops on Fission-Track Thermochronology -- Available Fission-Track Software / by Richard J. Weiland -- Call for Contributions to the May 1995 On Track Issue 10 -- Recent Fission-Track PapersUT Librarie
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