121 research outputs found
Tree level spontaneous R-symmetry breaking in O'Raifeartaigh models
We show that in O'Raifeartaigh models of spontaneous supersymmetry breaking,
R-symmetries can be broken by non-zero values of fields at tree level, rather
than by vacuum expectation values of pseudomoduli at loop level. As a
complement of the recent result by Shih, we show that there must be a field in
the theory with R-charge different from zero and two in order for R-symmetry
breaking to occur, no matter whether the breaking happens at tree or loop
level. We review the example by CDFM, and construct two types of tree level
R-symmetry breaking models with a wide range of parameters and free of runaway
problem. And the R-symmetry is broken everywhere on the pseudomoduli space in
these models. This provides a rich set of candidates for SUSY model building
and phenomenology.Comment: 8 pages; v2: major revision to section 6; v3: minor revision and
typos; v4: typos, published version; v5: fix Latex syntax error, published
versio
Exploring General Gauge Mediation
We explore various aspects of General Gauge Mediation(GGM). We present a
reformulation of the correlation functions used in GGM, and further elucidate
their IR and UV properties. Additionally we clarify the issue of UV sensitivity
in the calculation of the soft masses in the MSSM, highlighting the role of the
supertrace over the messenger spectrum. Finally, we present weakly coupled
messenger models which fully cover the parameter space of GGM. These examples
demonstrate that the full parameter space of GGM is physical and realizable.
Thus it should be considered a valid basis for future phenomenological
explorations of gauge mediation.Comment: 27 pages, minor changes, typos fixed in appendix
Zero Temperature Glass Transition in the Two-Dimensional Gauge Glass Model
We investigate dynamic scaling properties of the two-dimensional gauge glass
model for the vortex glass phase in superconductors with quenched disorder.
From extensive Monte Carlo simulations we obtain static and dynamic finite
size scaling behavior, where the static simulations use a temperature exchange
method to ensure convergence at low temperatures. Both static and dynamic
scaling of Monte Carlo data is consistent with a glass transition at zero
temperature. We study a dynamic correlation function for the superconducting
order parameter, as well as the phase slip resistance. From the scaling of
these two functions, we find evidence for two distinct diverging correlation
times at the zero temperature glass transition. The longer of these time scales
is associated with phase slip fluctuations across the system that lead to
finite resistance at any finite temperature, while the shorter time scale is
associated with local phase fluctuations.Comment: 8 pages, 10 figures; v2: some minor correction
Creating Bell states and decoherence effects in quantum dots system
We show how to improve the efficiency for preparing Bell states in coupled
two quantum dots system. A measurement to the state of driven quantum laser
field leads to wave function collapse. This results in highly efficiency
preparation of Bell states. The effect of decoherence on the efficiency of
generating Bell states is also discussed in this paper. The results show that
the decoherence does not affect the relative weight of and in the
output state, but the efficiency of finding Bell states.Comment: 4 pages, 2figures, corrected some typo
Bound Chains of Tilted Dipoles in Layered Systems
Ultracold polar molecules in multilayered systems have been experimentally
realized very recently. While experiments study these systems almost
exclusively through their chemical reactivity, the outlook for creating and
manipulating exotic few- and many-body physics in dipolar systems is
fascinating. Here we concentrate on few-body states in a multilayered setup. We
exploit the geometry of the interlayer potential to calculate the two- and
three-body chains with one molecule in each layer. The focus is on dipoles that
are aligned at some angle with respect to the layer planes by means of an
external eletric field. The binding energy and the spatial structure of the
bound states are studied in several different ways using analytical approaches.
The results are compared to stochastic variational calculations and very good
agreement is found. We conclude that approximations based on harmonic
oscillator potentials are accurate even for tilted dipoles when the geometry of
the potential landscape is taken into account.Comment: 10 pages, 6 figures. Submitted to Few-body Systems special issue on
Critical Stability, revised versio
R-symmetric gauge mediation
We present a version of Gauge Mediated Supersymmetry Breaking which preserves
an R-symmetry - the gauginos are Dirac particles, the A-terms are zero, and
there are four Higgs doublets. This offers an alternative way for gauginos to
acquire mass in the supersymmetry-breaking models of Intriligator, Seiberg, and
Shih. We investigate the possibility of using R-symmetric gauge mediation to
realize the spectrum and large sfermion mixing of the model of Kribs, Poppitz,
and Weiner.Comment: 26+ pages, 3 figures, BIBTEX; v2 published version: references added,
paragraph on spectrum running removed, section added on adjoint scalar
masses, clarification of the meaning of Table 3 adde
Thermodynamics of Dipolar Chain Systems
The thermodynamics of a quantum system of layers containing perpendicularly
oriented dipolar molecules is studied within an oscillator approximation for
both bosonic and fermionic species. The system is assumed to be built from
chains with one molecule in each layer. We consider the effects of the
intralayer repulsion and quantum statistical requirements in systems with more
than one chain. Specifically, we consider the case of two chains and solve the
problem analytically within the harmonic Hamiltonian approach which is accurate
for large dipole moments. The case of three chains is calculated numerically.
Our findings indicate that thermodynamic observables, such as the heat
capacity, can be used to probe the signatures of the intralayer interaction
between chains. This should be relevant for near future experiments on polar
molecules with strong dipole moments.Comment: 15 pages, 5 figures, final versio
Dimers, Effective Interactions, and Pauli Blocking Effects in a Bilayer of Cold Fermionic Polar Molecules
We consider a bilayer setup with two parallel planes of cold fermionic polar
molecules when the dipole moments are oriented perpendicular to the planes. The
binding energy of two-body states with one polar molecule in each layer is
determined and compared to various analytic approximation schemes in both
coordinate- and momentum-space. The effective interaction of two bound dimers
is obtained by integrating out the internal dimer bound state wave function and
its robustness under analytical approximations is studied. Furthermore, we
consider the effect of the background of other fermions on the dimer state
through Pauli blocking, and discuss implications for the zero-temperature
many-body phase diagram of this experimentally realizable system.Comment: 18 pages, 10 figures, accepted versio
An Integrated TCGA Pan-Cancer Clinical Data Resource to Drive High-Quality Survival Outcome Analytics
For a decade, The Cancer Genome Atlas (TCGA) program collected clinicopathologic annotation data along with multi-platform molecular profiles of more than 11,000 human tumors across 33 different cancer types. TCGA clinical data contain key features representing the democratized nature of the data collection process. To ensure proper use of this large clinical dataset associated with genomic features, we developed a standardized dataset named the TCGA Pan-Cancer Clinical Data Resource (TCGA-CDR), which includes four major clinical outcome endpoints. In addition to detailing major challenges and statistical limitations encountered during the effort of integrating the acquired clinical data, we present a summary that includes endpoint usage recommendations for each cancer type. These TCGA-CDR findings appear to be consistent with cancer genomics studies independent of the TCGA effort and provide opportunities for investigating cancer biology using clinical correlates at an unprecedented scale. Analysis of clinicopathologic annotations for over 11,000 cancer patients in the TCGA program leads to the generation of TCGA Clinical Data Resource, which provides recommendations of clinical outcome endpoint usage for 33 cancer types
Democratic Leadership - A local story
Leadership is traditionally viewed as an individual property and researched from the perspective of behaviours, traits or characteristics that these individuals possess. Notions of democratic leadership can offer early childhood centres a more expansive conception of leadership to include children, teachers and families.
This study explores the possibility of positioning all stakeholders in an early childhood centre as leaders by repositioning leadership as a jointly constructed, emergent process. Drawing on an existing feature of the kindergarten programme, that of regular excursions within the local community, connections are interwoven between childrenâs inquires, democratic principles and elements of place based education. Using narratives from five excursions in the local community the study experiments with Leadership-as-practice to analyse how these excursions fostered democratic and inclusive participation of children and adults. Inquiry as a form of participatory democracy is a key feature of decision-making and provides a common purpose for community excursions while encouraging leadership opportunities.
The study reveals the potential of leadership-as-practice, underpinned by democratic values as an approach to leadership in early childhood organisations, enabling leader/follower roles to be blurred and learning to be co constructed during dialogue. The local community holds enormous capacity as a system to facilitate democratic leadership and promote place based learning and citizenship education. This study recognises that democratic leadership exists in tension with current neo liberal beliefs and therefore positions itself as a counter to the current market driven early childhood environment.
The underlying belief of this study is that leadership can occur as a collaborative practice, emerging through day to day experiences and seeks to contribute to the slowly emerging body of research concerned with early childhood leadership.
- âŠ