350 research outputs found
Mass generation and the dynamical role of the Katoptron Group
Heavy mirror fermions along with a new strong gauge interaction capable of
breaking the electroweak gauge symmetry dynamically were recently introduced
under the name of katoptrons. Their main function is to provide a viable
alternative to the Standard-Model Higgs sector. In such a framework, ordinary
fermions acquire masses after the breaking of the strong katoptron group which
allows mixing with their katoptron partners. The purpose of this paper is to
study the elementary-scalars-free mechanism responsible for this breaking and
its implications for the fermion mass hierarchies.Comment: 15 LaTeX pages, some comments added, version published in Modern
Physics Letters
New physics with mirror particles
The introduction of mirror fermions with masses between the weak scale and 1
TeV could offer a dynamical origin to the standard-model electro-weak symmetry
breaking mechanism. The purpose of this work is to study the dynamics needed in
order to render models with such a fermion content phenomenologically
acceptable.Comment: 28 LaTeX pages, to appear in the Journal of Physics
Longitudinal and transverse fermion-boson vertex in QED at finite temperature in the HTL approximation
We evaluate the fermion-photon vertex in QED at the one loop level in Hard
Thermal Loop approximation and write it in covariant form. The complete vertex
can be expanded in terms of 32 basis vectors. As is well known, the
fermion-photon vertex and the fermion propagator are related through a
Ward-Takahashi Identity (WTI). This relation splits the vertex into two parts:
longitudinal (Gamma_L) and transverse (Gamma_T). Gamma_L is fixed by the WTI.
The description of the longitudinal part consumes 8 of the basis vectors. The
remaining piece Gamma_T is then written in terms of 24 spin amplitudes.
Extending the work of Ball and Chiu and Kizilersu et. al., we propose a set of
basis vectors T^mu_i(P_1,P_2) at finite temperature such that each of these is
transverse to the photon four-momentum and also satisfies T^mu_i(P,P)=0, in
accordance with the Ward Identity, with their corresponding coefficients being
free of kinematic singularities. This basis reduces to the form proposed by
Kizilersu et. al. at zero temperature. We also evaluate explicitly the
coefficient of each of these vectors at the above-mentioned level of
approximation.Comment: 13 pages, uses RevTe
Alternating diatomaceous and volcaniclastic deposits in Milos Island, Greece. A contribution to the upper Pliocene–lower Pleistocene stratigraphy of the Aegean Sea
In the northern part of Milos Island, South Aegean Volcanic Arc, a stratigraphic succession spanning the late Pliocene and early Pleistocene exceeds 300 m in thickness and records an alternation of products from submarine volcanic explosive events and fossiliferous, both siliceous and carbonate marine sedimentary rocks. The accumulation of volcaniclastic deposits took place under subaqueous marine conditions as evidenced by sedimentary features, scarce fossil remains and the local presence of burrow traces. Each major volcanic event was represented by the accumulation of thick-bedded pumice and glassy tuffs, succeeded by the deposition of marine sediments composed mainly of laminated diatomaceous marlstone and sandy limestone. The silica content of the diatomaceous sediments varies from 39% to 70%, mostly in the form of biogenic opal-A. SiO2/Al2O3 ratios ranging from 5 to 21 indicate a varied contribution of reworked volcanic grains. The sequential arrangement of basinal diatomaceous marlstone and shoreface sandy limestone deposits suggests that the depth of water was not great, which is also consistent with features observed in the volcaniclastic deposits. Calcareous nannofossils from the upper part of the succession of northern Milos allow biostratigraphic correlation with nannofossil biozones MNN19a–MNN19b across the Gelasian/Calabrian boundary within the early Pleistocene. A late Pliocene (Piacenzian) age has been estimated for the lower part of the section, where biozone MNN16a has been documented. Diatoms, planktonic foraminifera and calcareous nannofossil assemblages in the diatomaceous beds point to deposition in a partially closed, relatively shallow marine environment. In this setting,warmand stratified water conditions can be concluded for the Piacenzian diatomaceous beds whereas highly productive cool waters are inferred from the Gelasian/Calabrian diatomite
Chiral Symmetry Breaking via Multi-fermion Green Functions
Previous results on fermion chirality-flipping four-point functions are
extended to gauge theories. The problem is purely non-perturbative, and
it is approached by truncating the Schwinger-Dyson hierarchy. The large-
limit also simplifies the problem substantially. The resulting equation is
solved numerically by relaxation techniques and an estimate of the critical
coupling and momentum behavior is obtained. We also comment on the behavior of
chirality-flipping -point functions for general .Comment: 17 pages, LaTeX + 3 figures, version to be publishe
Soft Supersymmetry Breaking due to Dimensional Reduction over Non-Symmetric Coset Spaces
A ten-dimensional supersymmetric gauge theory is compactified over
six-dimensional coset spaces, establishing further our earlier conjecture that
the resulting four dimensional theory is a softly broken supersymmetric gauge
theory in the case that the used coset space is non-symmetric. The specific
non-symmetric six-dimensional spaces examined in the present study are
and .Comment: 14 pages, Latex, Comments related to the Scherk-Schwarz mechanism and
relevant references adde
Remarks on the Messinian evaporites of Zakynthos Island (Ionian Sea, Eastern Mediterranean)
Detailed mapping of the Neogene deposits on Zakynthos Island shows that the Messinian primary evaporite basins, formed over Ionian basement, are delimited by the westernmost outcrop of the Triassic evaporitic diapirs, located west of the Kalamaki-Argasi Messinian gypsum unit. The post-Miocene external Ionian thrust is emplaced west of the Triassic diapirs. Planktonic foraminifera biostratigraphy indicates that primary evaporite accumulation took place probably during the first stage of the Messinian salinity crisis (5.96-5.60 Ma), in shallower parts of a foreland basin, formed over the Pre-Apulian and the Ionian zone basement. Establishment of these depositional environments, before the Ionian thrust emplacement, was probably due to the particularities of the foreland basin, which extended from the external Ionian to the internal Pre-Apulian zone. Field observations, borehole data and an onshore seismic profile show that the Neogene sediments over the Pre-Apulian basement correspond to the foredeep through forebulge domain of the foreland basin, as it is documented from their spatial thickness distribution. In contrast, the Neogene sediments over the Ionian basement correspond to the wedge top of the foreland basin, which was less subsiding, as it is deduced by their reduced thickness. This lower subsidence rate was the result of the concurrent diapiric movements of the Ionian Triassic evaporites. In Agios Sostis area, located over Pre-Apulian basement, the Neogene sequence is intercalated by decametre-thick resedimented blocks consisting of shallow water selenite. To the southeast, this mass-wasting Messinian gypsum passes to mainly gypsum turbidite. In Kalamaki-Argasi area, located over Ionian basement, the shallow water environment led to the deposition of the observed primary gypsum. Erosion of the primary gypsum of both forebulge and wedge top supplied the foreland basin’s depocenter with gypsum turbidites.
Η λεπτομερής χαρτογράφηση των Νεογενών αποθέσεων της Ζακύνθου δείχνει ότι οι λεκάνες πρωτογενούς Μεσσήνιας εβαποριτικής απόθεσης, που σχηματίστηκαν πάνω σε Ιόνιο υπόβαθρο, οριοθετούνται από τη δυτικότερη εμφάνιση των Τριαδικών εβαποριτικών διάπειρων (δυτικά της Μεσσήνιας ενότητας γύψου Καλαμάκι-Αργάσι). Η μετα-Μειοκαινική εξωτερική Ιόνια επώθηση τοποθετείται δυτικά αυτών των Τριαδικών διάπειρων. Βιοστρωματογραφική ανάλυση των συναθροίσεων πλαγκτονικών τρηματοφόρων στα Νεογενή ιζήματα δείχνει ότι η συσσώρευση πρωτογενούς εβαπορίτη έλαβε χώρα πιθανά κατά το πρώτο στάδιο της κρίσης αλμυρότητας του Μεσσηνίου (5.96-5.60 Εκατ.χρ.), στα αβαθέστερα τμήματα της λεκάνης προχώρας, η οποία σχηματίστηκε πάνω στο Προ-Απούλιο και Ιόνιο αλπικό υπόβαθρο. Ο σχηματισμός των περιβαλλόντων ιζηματογένεσης, πριν από την Ιόνια επώθηση, πιθανά οφείλεται στις ιδιαιτερότητες της λεκάνης προχώρας, η οποία εκείνο το διάστημα εκτείνονταν από την εξωτερική Ιόνια ως την εσωτερική Προ-Απούλια ζώνη. Νέα δεδομένα υπαίθρου, σε συνδυασμό με τη βιοστρωματογραφία, τα στοιχεία γεωτρήσεων και μία διαθέσιμη σεισμική τομή δείχνουν ότι τα Νεογενή ιζήματα πάνω στο Προ-Απούλιο υπόβαθρο αντιστοιχούν στον τμήμα της λεκάνης προχώρας, από το προβύθισμα (foredeep) ως την πρόσθια ανύψωση (forebulge), όπως αυτό διαπιστώνεται από την χωρική κατανομή του πάχους τους. Αντίθετα, τα Νεογενή ιζήματα πάνω στο Ιόνιο υπόβαθρο αντιστοιχούν στο τμήμα της λεκάνης προχώρας που βρίσκεται πάνω στο μετωπικό πρίσμα της ορογένεσης (wedge top), το οποίο βυθίζονταν λιγότερο όπως συνάγεται από το ελαττωμένο πάχος των ιζημάτων. Ο μικρότερος ρυθμός βύθισης οφείλεται στις διαπειρικές κινήσεις των Τριαδικών εβαποριτών. Στη Νεογενή ακολουθία, που βρίσκεται πάνω σε Προ-Απούλιο υπόβαθρο (περιοχή Άγιος Σώστης), παρεμβάλλονται επανιζηματοποιημένα μπλοκ δεκαμετρικού πάχους αποτελούμενα από σεληνίτη μικρού βάθους απόθεσης. Προς νότο, αυτή η βαρυτικά μεταφερόμενη μάζα της Μεσσήνιας γύψου μεταπίπτει κυρίως σε τουρβιδιτική γύψο. Στην περιοχή Καλαμάκι-Αργάσι που βρίσκεται πάνω σε Ιόνιο υπόβαθρο, το αβαθές περιβάλλον οδήγησε στην απόθεση της παρατηρούμενης πρωτογενούς γύψου. Η διάβρωση της πρωτογενούς γύψου τόσο της πρόσθιας ανύψωσης όσο και του μετωπικού πρίσματος επώθησης τροφοδότησαν το προβύθισμα της λεκάνης προχώρας με τουρβιδίτες γύψου
- …