2,753 research outputs found
The tension between gauge coupling unification, the Higgs boson mass, and a gauge-breaking origin of the supersymmetric mu-term
We investigate the possibility of generating the -term in the MSSM by
the condensation of a field that is a singlet under the SM gauge group but
charged under an additional family-independent gauge symmetry. We
attempt to do so while preserving the gauge coupling unification of the MSSM.
For this, we find that SM non-singlet exotics must be present in the spectrum.
We also prove that the pure anomalies can always be solved with
rationally charged fields, but that a large number of SM singlets are often
required. For charges that are consistent with an embedding of the
MSSM in SU(5) or SO(10), we show that the charges of the MSSM states
can always be expressed as a linear combination of abelian subgroups of .
However, the SM exotics do not appear to have a straightforward embedding into
GUT multiplets. We conclude from this study that if this approach to the
-term is correct, as experiment can probe, it will necessarily complicate
the standard picture of supersymmetric grand unification.Comment: 10 pages, no figure
How Can a Heavy Higgs Boson be Consistent with the Precision Electroweak Measurements?
The fit of precision electroweak data to the Minimal Standard Model currently
gives an upper limit on the Higgs boson mass of 170 GeV at 95% confidence.
Nevertheless, it is often said that the Higgs boson could be much heavier in
more general models. In this paper, we critically review models that have been
proposed in the literature that allow a heavy Higgs boson consistent with the
precision electroweak constraints. All have unusual features, and all can be
distinguished from the Minimal Standard Model either by improved precision
measurements or by other signatures accessible to next-generation colliders.Comment: 25 pages, 5 eps figures. Source contains html and jar files which
make Fig. 1 active. v.3: final corrections and added reference
Cosmic Archaeology with Gravitational Waves from Cosmic Strings
Cosmic strings are generic cosmological predictions of many extensions of the
Standard Model of particle physics, such as a symmetry breaking
phase transition in the early universe or remnants of superstring theory.
Unlike other topological defects, cosmic strings can reach a scaling regime
that maintains a small fixed fraction of the total energy density of the
universe from a very early epoch until today. If present, they will oscillate
and generate gravitational waves with a frequency spectrum that imprints the
dominant sources of total cosmic energy density throughout the history of the
universe. We demonstrate that current and future gravitational wave detectors,
such as LIGO and LISA, could be capable of measuring the frequency spectrum of
gravitational waves from cosmic strings and discerning the energy composition
of the universe at times well before primordial nucleosynthesis and the cosmic
microwave background where standard cosmology has yet to be tested. This work
establishes a benchmark case that gravitational waves may provide an
unprecedented, powerful tool for probing the evolutionary history of the very
early universe.Comment: 6 pages, 3 figure
Holomorphic selection rules, the origin of the mu term, and thermal inflation
When an abelian gauge theory with integer charges is spontaneously broken by
the expectation value of a charge Q field, there remains a Z_Q discrete
symmetry. In a supersymmetric theory, holomorphy adds additional constraints on
the operators that can appear in the effective superpotential. As a result,
operators with the same mass dimension but opposite sign charges can have very
different coupling strengths. In the present work we characterize the operator
hierarchies in the effective theory due to holomorphy, and show that there
exist simple relationships between the size of an operator and its mass
dimension and charge. Using such holomorphy-induced operator hierarchies, we
construct a simple model with a naturally small supersymmetric mu term. This
model also provides a concrete realization of late-time thermal inflation,
which has the ability to solve the gravitino and moduli problems of weak-scale
supersymmetry.Comment: 18 pages, 1 figur
The implementation of performance analysis and feedback within Olympic sport: the performance analyst’s perspective
The study considered performance analysis and feedback from the perspective of the performance analyst through the investigation of the ‘what’, ‘how’, and ‘when’ of practice within a selection of Olympic sports. Twenty-three performance analysts (experience 6.4 ± 4.1 years) engaged in a structured interview (85 ± 15 minutes) regarding their processes within applied practice. Likert scales (All the time, Often, Sometimes, Rarely, Never) were used to facilitate cross sport and environment comparison. The performance analysts highlighted the experience of their coaches as the most prominent feature influencing analysis direction and time had the greatest impact upon feedback provision. The main analysis techniques used were video, profiling and performance reports. Feedback was delivered primarily either, 1) < 1-hour post-performance within sessions lasting < 10-minutes or 2) the following day within sessions lasting 25+ minutes. Video feedback was usually coach led, however data delivery was more evenly distributed between coach and analyst. Very similar processes across the participants were identified, despite a wide variety of sports and participant experience levels. The findings have begun to illustrate practice within elite sport whilst highlighting the importance and need for further practitioner-based investigation regarding the use of performance analysis and feedback within applied context
Elite coaches’ use and engagement with performance analysis within Olympic and Paralympic sport
The use and implementation of performance analysis and feedback by 18 elite Olympic/Paralympic coaches (coaching experience 16.1 ± 7.4; experience using performance analysis 8.3 ± 4.8 years) was explored via an online questionnaire (mean time to complete = 29 minutes). Likert scales were used to facilitate cross-sport comparison. Comment boxes were included to enable additional information to be provided if deemed necessary. Training goals, athlete discussion and coaching philosophy were the most prominent features influencing analysis direction. Time available had the greatest impact upon feedback provision. The main analysis techniques used were video, performance reports, and trend analysis. Coaches with greater experience delivered significantly more feedback sessions within 1-hour of performance. Feedback sessions were < 20-minutes in duration and delivered in a balanced (experienced) or mostly positive (inexperienced) approach. Feedback was delivered consistently according to a preferred schedule, face-to-face, and within an individual format. Sessions were usually coach led, however considerable value in a combined or analyst led approach was demonstrated. The findings have begun to illustrate practice within elite sport from the perspective of a key user of performance analysis, i.e. the coach, and have clear implications for practitioners by identifying the key areas coaches’ value from performance analysis
Drawdown of Soil Test Phosphorus and Potassium levels by Alfalfa
Alfalfa hay production removes large amounts of phosphorus (P) and potassium (K) from soils. Because of this, there is always interest in the reduction of soil test phosphorus (STP) and soil test potassium (STK) levels by high-yielding alfalfa. Periodic soil sampling for 2 years during an on-farm· fertilizer study on a high yielding alfalfa field provided an insight into this
Precision Agriculture: The Effect of Variable Rate Fertilizer Application On Soil Test Values
Use of variable rate fertilizer spreaders (VRS) is available to farmers in many areas of Kentucky. For use of VRS, a soil fertility map must be prepared for the field to be spread which requires subdividing the field into subunits. Each subunit is then soil sampled separately. A common procedure in commercial use is to grid a field into 2.5 acre blocks and to take a composite sample of 6-8 cores along the perimeter of a circular radius of 60-80 ft from the center of each block. Each block receives a separate fertilizer recommendation based on results from the soil test. With this information, a VRS can be programmed to apply the recommended rate of fertilizer on-the-go to each specific block as it drives across the field. The objective is to direct the amount (or kind) of fertilizer to soil test variations which occur within the field. This approach assumes that the result from each soil sample of each block uniformly represents the soil test level for all the area within that block. It also assumes that the VRS applies fertilizer (amount and kind) uniformly across its swath width and along the pathway it is driven across each block. These assumptions may be questionable. We conducted a study to measure soil test levels within blocks of a field which had been soil tested on a grid, before fertilizer was applied and at harvest, 6 months later. The objective was to define soil test variability within blocks before and after VRS fertilization. This information should provide insight into the effectiveness of on-the-go VRS fertilizer application in lowering soil test variability between individual blocks
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