4,364 research outputs found
Affleck-Dine Sneutrino Inflation
Motivated by the coincidence between the Hubble scale during inflation and
the typical see-saw neutrino mass scale, we present a supergravity model where
the inflaton is identified with a linear combination of right-handed sneutrino
fields. The model accommodates an inflaton potential that is flatter than
quadratic chaotic inflation, resulting in a measurable but not yet ruled out
tensor-to-scalar ratio. Small CP-violation in the neutrino mass matrix and
supersymmetry breaking yield an evolution in the complex plane for the
sneutrino fields. This induces a net lepton charge that, via the Affleck-Dine
mechanism, can be the origin of the observed baryon asymmetry of the universe.Comment: 5 pages, 1 figur
Revisiting Flavor and CP Violation in Supersymmetric SU(5) with Right-Handed Neutrinos
We revisit the minimal supersymmetric SU(5) grand unified theory with three
right-handed neutrinos in which universality conditions for soft-supersymmetry
breaking parameters are imposed at an input scale above the unification scale.
If the Majorana masses for the neutrinos are around GeV, large mixing
angles and phases in the neutrino sector lead to flavor-violation and
CP-violation in the right-handed down squark and left-handed slepton sectors.
Since the observed Higgs boson mass and the proton decay constraints indicate
sfermions have masses larger than a few TeV, flavor and CP constraints are less
restrictive. We explore the constraints on models with a universal
soft-supersymmetry breaking input parameters coming from proton stability,
electric dipole moments, decays, and the Higgs mass observed
at the LHC. Regions compatible with all constraints can be found if non-zero
A-terms are taken.Comment: 28 pages, 4 figures, version accepted PR
A Minimal SU(5) SuperGUT in Pure Gravity Mediation
The lack of evidence for low-scale supersymmetry suggests that the scale of
supersymmetry breaking may be higher than originally anticipated. However,
there remain many motivations for supersymmetry including gauge coupling
unification and a stable dark matter candidate. Models like pure gravity
mediation (PGM) evade LHC searches while still providing a good dark matter
candidate and gauge coupling unification. Here, we study the effects of PGM if
the input boundary conditions for soft supersymmetry breaking masses are pushed
beyond the unification scale and higher dimensional operators are included. The
added running beyond the unification scale opens up the parameter space by
relaxing the constraints on . If higher dimensional operators
involving the SU(5) adjoint Higgs are included, the mass of the heavy gauge
bosons of SU(5) can be suppressed leading to proton decay, ,
that is within reach of future experiments. Higher dimensional operators
involving the supersymmetry breaking field can generate additional
contributions to the A- and B-terms of order . The threshold effects
involving these A- and B-terms significantly impact the masses of the gauginos
and can lead to a bino LSP. In some regions of parameter space the bino can be
degenerate with the wino or gluino and give an acceptable dark matter relic
density.Comment: 37 pages, 27 figure
Low-Scale D-term Inflation and the Relaxion
We present a dynamical cosmological solution that simultaneously accounts for
the early inflationary stage of the Universe and solves the supersymmetric
little hierarchy problem via the relaxion mechanism. First, we consider an
inflationary potential arising from the -term of a new gauge symmetry
with a Fayet--Iliopolous term, that is independent of the relaxion. A
technically natural, small gauge coupling, , allows
for a low Hubble scale of inflation, GeV, which is shown to
be consistent with Planck data. This feature is then used to realize a
supersymmetric two-field relaxion mechanism, where the second field is
identified as the inflaton provided that GeV. The inflaton
controls the relaxion barrier height allowing the relaxion to evolve in the
early Universe and scan the supersymmetric soft masses. After electroweak
symmetry is broken, the relaxion settles at a local supersymmetry-breaking
minimum with a range of -term values that can naturally explain
supersymmetric soft mass scales up to GeV.Comment: 37 pages, 4 figure
Naturalizing Supersymmetry with a Two-Field Relaxion Mechanism
We present a supersymmetric version of a two-field relaxion model that
naturalizes tuned versions of supersymmetry. This arises from a relaxion
mechanism that does not depend on QCD dynamics and where the relaxion potential
barrier height is controlled by a second axion-like field. During the
cosmological evolution, the relaxion rolls with a nonzero value that breaks
supersymmetry and scans the soft supersymmetric mass terms. Electroweak
symmetry is broken after the soft masses become of order the supersymmetric
Higgs mass term and causes the relaxion to stop rolling for superpartner masses
up to GeV. This can explain the tuning in supersymmetric models,
including split-SUSY models, while preserving the QCD axion solution to the
strong CP problem. Besides predicting two very weakly-coupled axion-like
particles, the supersymmetric spectrum may contain an extra Goldstino, which
could be a viable dark matter candidate.Comment: 33 pages, 3 figures; v2: bounds and figures correcte
Modelling Climate - Surface Hydrology Interactions in Data Sparse Areas
This thesis develops tools aimed at the study and prediction of climate effects on land-surface hydrology (in particular streamflow), which require a minimum amount of site specific data. This minimum data requirement allows studies to be performed in areas that are data sparse, such as the developing world. ¶ ..
A test of resource dependency theory using higher education institution behavioral changes after state based merit aid adoption
Field of study: Educational leadership and policy analysis.Dr. Brad Curs, Dissertation Supervisor.Includes vita."May 2018."The purpose of this study was to analyze whether four-year, public institutions altered their behaviors as their revenue streams changed. I utilized state based merit aid adoption to examine whether institutions altered their functional expenditures and faculty employment behaviors as institutions became more resource dependent on students. The dependent variables concerning functional expenditures analyzed were instruction, research, student services, public services, academic support, institutional support, and scholarships. The dependent variables concerning faculty employment analyzed were part-time faculty, full-time non-tenure-track faculty, and fulltime tenure-track faculty. A difference-in-difference estimation strategy estimated institutional responses to a merit aid program being adopted in their state. The findings indicated that after merit aid adoption in their state, institutions altered their behaviors in ways that indicated they became more resource dependent on students. Specifically, the models indicated that, on average, institutions in states that adopted a merit aid program spent more money on instruction, institutional support, and scholarships and employed more part-time faculty than institutions in states that did not adopt any merit aid program. The findings of this study suggest that if states direct funds to students that institutions will respond as though the students provide the funding and not the state.Includes bibliographical references (pages 213-229)
“Inspiring Imps”: programme evaluation of a football intervention targeting mentally ill health services users through a professional football club
The Active People survey (2010) shows that only 6.5% of disabled individuals participate in sport and exercise 3 times per week, compared with 16.5% of able bodied adults in the UK. Individuals with recognised disabilities have long been excluded from mainstream society. Particularly in sport, disability athletes can be afforded minority status and are treated as such (Nixon, 2000: In Handbook of Sports Studies, edited by J. Coakley and E. Dunning. London: Sage). This stigmatisation can be particularly acute among participants with diagnosed mental or psychological disabilities. Previous research concluded that sport can have positive psychological and social benefits, including improved well-being, motivation and social confidence (Crone and Guy, 2008: International Journal of Mental Health Nursing. 17, 197-207.).
The aim of the present study was to investigate the feasibility of a 6 week exercise programme targeting mental ill health service users aged 16+. A weekly 2 hour session of football was introduced to promote health and wellbeing in the target group. Partners included county Football Association and a professional football club. The project enhanced local partnerships and partnerships with other professional football clubs. The key remaining aim is to ensure a sustainable “legacy” is achieved to ensure the continuation delivery of the project.
The feasibility of the present study will be assessed using programme evaluation. Programme evaluation uses programme theory to produce a structured framework for assessment of the project (Rossi et al 2004; Evaluation: A systematic Approach. London, Sage). This allows a clear and logical progression from planning to implementation. Participant attrition rates and attendance records will be collected. These data will be supplemented with semi-structured interviews with participants and project stakeholders to assess programme development. The expected overall project outcome is to produce shared learning practice on similar interventions nationwide
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