140 research outputs found
A partially composite Goldstone Higgs
We consider a model of dynamical electroweak symmetry breaking with a
partially composite Goldstone Higgs. The model is based on a
strongly-interacting fermionic sector coupled to a fundamental scalar sector
via Yukawa interactions. The SU(4) x SU(4) global symmetry of these two sectors
is broken to a single SU(4) via Yukawa interactions. Electroweak symmetry
breaking is dynamically induced by condensation due to the strong interactions
in the new fermionic sector which further breaks the global symmetry SU(4) to
Sp(4). The Higgs boson arises as a partially composite state which is an exact
Goldstone boson in the limit where SM interactions are turned off. Terms
breaking the SU(4) global symmetry explicitly generate a mass for the Goldstone
Higgs. The model realizes in different limits both (partially) composite Higgs
and (bosonic) Technicolor models, thereby providing a convenient unified
framework for phenomenological studies of composite dynamics. It is also a
dynamical extension of the recent elementary Goldstone-Higgs model.Comment: 7 pages, 7 figure
Axiflavon-Higgs Unification
In this talk, a unified model of scalar particles that addresses the flavour hierarchies, solves the strong CP problem, delivers a dark matter candidate, and radiatively triggers electroweak symmetry breaking is discussed. The recently proposed axiflavon is embedded together with an (elementary) Goldstone Higgs-sector in a single multiplet (and thereby also a model of flavour and strong CP conservation for the latter is provided). Bounds on the axion decay constant follow from requiring a SM-like Higgs potential at low energies and are confronted with constraints from flavour physics and astrophysics. In the minimal implementation, the axion decay constant is restricted to GeV, while adding right-handed neutrinos allows for a heavy-axion model at lower energies, down to TeV
Diversity of actin architecture in human osteoclasts: Network of curved and branched actin supporting cell shape and intercellular micrometer level tubes
Osteoclasts are multinucleated bone-resorbing cells with a dynamic actin
cytoskeleton. Osteoclasts are derived from circulating mononuclear
precursors. Confocal and stimulated emission depletion (STED)
super-resolution microscopy was used to investigate peripheral
blood-derived human osteoclasts cultured on glass surfaces. STED and
confocal microscopy demonstrated that the actin was curved and branched,
for instance, in the vicinity of membrane ruffles. The overall
architecture of the curved actin network extended from the podosomes to
the top of the cell. The other novel finding was that a micrometer-level
tube containing actin bridged the osteoclasts well above the level of
the culture glass. The actin filaments of the tubes originated from the
network of curved actin often surrounding a group of nuclei.
Furthermore, nuclei were occasionally located inside the tubes. Our
findings demonstrated the accumulation of c-Src, cortactin, cofilin, and
actin around nuclei suggesting their role in nuclear processes such as
the locomotion of nuclei. ARP2/3 labeling was abundant at the substratum
level of osteoclasts and in the branched actin network, where it
localized to the branching points. We speculate that the
actin-containing tubes of osteoclasts may provide a means of
transportation of nuclei, e.g., during the fusion of osteoclasts. These
novel findings can pave the way for future studies aiming at the
elucidation of the differentiation of multinucleated osteoclasts.</p
In vitro model of bone to facilitate measurement of adhesion forces and super-resolution imaging of osteoclasts
To elucidate processes in the osteoclastic bone resorption, visualise resorption and related actin reorganisation, a combination of imaging technologies and an applicable in vitro model is needed. Nanosized bone powder from matching species is deposited on any biocompatible surface in order to form a thin, translucent, smooth and elastic representation of injured bone. Osteoclasts cultured on the layer expressed matching morphology to ones cultured on sawed cortical bone slices. Resorption pits were easily identified by reflectance microscopy. The coating allowed actin structures on the bone interface to be visualised with super-resolution microscopy along with a detailed interlinked actin networks and actin branching in conjunction with V-ATPase, dynamin and Arp2/3 at actin patches. Furthermore, we measured the timescale of an adaptive osteoclast adhesion to bone by force spectroscopy experiments on live osteoclasts with bone-coated AFM cantilevers. Utilising the in vitro model and the advanced imaging technologies we localised immunofluorescence signals in respect to bone with high precision and detected resorption at its early stages. Put together, our data supports a cyclic model for resorption in human osteoclasts.</p
A second Higgs doublet in the early universe: baryogenesis and gravitational waves
We show that simple Two Higgs Doublet models still provide a viable explanation for the matter-antimatter asymmetry of the Universe via electroweak baryogenesis, even after taking into account the recent order-of-magnitude improvement on the electron-EDM experimental bound by the ACME Collaboration. Moreover we show that, in the region of parameter space where baryogenesis is possible, the gravitational wave spectrum generated at the end of the electroweak phase transition is within the sensitivity reach of the future space-based interferometer LISA
Sp(4) gauge theory on the lattice: towards SU(4)/Sp(4) composite Higgs (and beyond)
The Sp(4) gauge theory with two Dirac fundamental flavours provides a candidate for the microscopic origin of composite-Higgs models based on the SU(4)/Sp(4) coset. We employ a combination of two different, complementary strategies for the numerical lattice calculations, based on the Hybrid Monte Carlo and on the Heat Bath algorithms. We perform pure Yang-Mills, quenched computations and exploratory studies with dynamical Wilson fermions. We present the first results in the literature for the spectrum of glueballs of the pure Sp(4) Yang-Mills theory, an EFT framework for the interpretation of the masses and decay constants of the lightest pion, vector and axial-vector mesons, and a preliminary calculation of the latter in the quenched approximation. We show the first numerical evidence of a bulk phase transition in the lattice theory with dynamical Wilson fermions, and perform the technical steps necessary to set up future investigations of the mesonic spectrum of the full theory
Symmetry restoration at high-temperature in two-color and two-flavor lattice gauge theories
We consider the SU(2) gauge theory with Nf=2 flavors of Dirac fundamental fermions. We study the high-temperature behavior of the spectra of mesons, discretizing the theory on anisotropic lattices, and measuring the two-point correlation functions in the temporal direction as well as screening masses in various channels. We identify the (pseudo-)critical temperature as the temperature at which the susceptibility associated with the Polyakov loop has a maximum. At high temperature both the spin-1 and spin-0 sectors of the light meson spectra exhibit enhanced symmetry properties, indicating the restoration of both the global SU(4) and the axial U(1)A symmetries of the model
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