Planning Family Spending

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Four boosted tops from a Regge gluon

The hierarchy problem can by addressed by extending the four-dimensional space-time to include an extra compact spatial dimension with non-trivial "warped" metric, as first suggested by Randall and Sundrum. If the Randall-Sundrum framework is realized in string theory, and if the Standard Model particles propagate in the extra dimension, Regge excitations of the Standard Model states should appear around the TeV scale. In a previous publication, we proposed a field-theoretic framework to model the tensor (spin-2) Regge partner of the gluon. Here, we use this framework to study the collider phenomenology of this particle. We find that Regge gluon decays involving Kaluza-Klein (KK) partners of Standard Model fields are very important. In particular, the decay to two KK gluons (with one possibly off-shell) dominates in most of the parameter space. This decay produces a very distinctive experimental signature: four highly boosted top quarks. We present a preliminary study of the detection prospects for this signal at the Large Hadron Collider (LHC). We find that Regge gluons masses up to about 2 TeV can be probed with 10 inverse femtobarns of data at 7 TeV center-of-mass energy. With design luminosity at 14 TeV, the LHC should be sensitive to Regge gluon masses up to at least 3.5 TeV.Comment: 24 pages, 10 figures. Published version: new section

Electroweak Multiplet Dark Matter at Future Lepton Colliders

An electroweak multiplet stable due to a new global symmetry is a simple and well-motivated candidate for thermal dark matter. We study how direct searches at a future linear collider, such as the proposed CLIC, can constrain scalar and fermion triplets, quintets and septets, as well as a fermion doublet. The phenomenology is highly sensitive to charged state lifetimes and thus the mass splitting between the members of the multiplet. We include both radiative corrections and the effect of non-renormalisable operators on this splitting. In order to explore the full range of charged state lifetimes, we consider signals including long-lived charged particles, disappearing tracks, and monophotons. By combining the different searches we find discovery and exclusion contours in the mass-lifetime plane. In particular, when the mass splitting is generated purely through radiative corrections, we can exclude the pure-Higgsino doublet below 310 GeV, the pure-wino triplet below 775 GeV, and the minimal dark matter fermion quintet below 1025 GeV. The scenario where the thermal relic abundance of a Higgsino accounts for the whole dark matter of the Universe can be excluded if the mass splitting between the charged and neutral states is less than 230 MeV. Finally, we discuss possible improvements to these limits by using associated hard leptons to idenify the soft visible decay products of the charged members of the dark matter multiplet.Comment: 24 pages, 14 figures; version 2, additional reference

Viscosity determinations of some frictionally generated silicate melts: Implications for slip zone rheology during impact-induced faulting

Analytical scanning electron microscopy, using combined energy dispersive and wavelength dispersive spectrometry, was used to determine the major-element compositions of some natural and artificial glasses and their crystalline equivalents derived by the frictional melting of acid to intermediate protoliths. The major-element compositions are used to calculate the viscosities of their melt precursors using the model of Shaw at temperatures of 800-1400 C, with Fe(2+)/Fe(tot) = 0.5 and for 1-3 wt percent H2O. These results are then modified to account for suspension effects in order to determine viscosities. The results have implications for the generation of pseudotachylitic breccias as seen in the basement lithologies of the Sudbury and Vredefort structures and possibly certain dimict lunar breccias. Many of these breccias show similarities with the more commonly developed pseudotachylite fault and injection veins seen in endogenic fault zones that typically occur in thicknesses of a few centimeters or less. The main difference is one of scale: Impact-induced pseudotachylite breccias can attain several meters in thickness. This would suggest that they were generated under exceptionally high slip rates and hence high strain rates and that the friction melts generated possessed extremely low viscosities

Low-Temperature Enhancement of Semi-annihilation and the AMS-02 Positron Anomaly

Semi-annihilation is a generic feature of particle dark matter that is most easily probed by cosmic ray experiments. We explore models where the semi-annihilation cross section is enhanced at late times and low temperatures by the presence of an s-channel resonance near threshold. The relic density is then sensitive to the evolution of the dark matter temperature, and we compute expressions for the associated Boltzmann equation valid in general semi-annihilating models. At late times, a self-heating effect warms the dark matter, allowing number-changing processes to remain effective long after kinetic decoupling of the dark and visible sectors. This allows the semi-annihilation signal today to be enhanced by up to five orders of magnitude over the thermal relic cross section. As a case study, we apply this to a dark matter explanation of the positron excess seen by AMS-02. We see that unlike annihilating dark matter, our model has no difficulty fitting the data while also giving the correct relic density. However, constraints from the CMB and $\gamma$-rays from the galactic centre do restrict the preferred regions of parameter space.Comment: 32 pages, 5 figures; minor update

Antecedents of approach-avoidance achievement goal adoption in physical education: A longitudinal perspective

The purpose of this study was to examine the temporal pattern of pupils’ approach-avoidance achievement goal adoption in physical education across Key Stage 3 of secondary school. Moreover, we determined the predictive utility of implicit theories of ability and perceived competence in explaining change in achievement goals, along with the moderating influence of pupils’ year group. On four occasions, over a 9-month period, 511 pupils in Years 7, 8, and 9 completed measures of perceived competence, incremental and entity beliefs, and approach-avoidance goals. Mastery-approach, mastery-avoidance, and performance-avoidance goals exhibited a linear decline over time, whereas performance-approach goals showed no significant change. Theoretical propositions regarding the antecedents of approach-avoidance goal adoption were supported. Year group was found to moderate a number of these antecedent-goal relationships. Results suggest that Year 7 is a critical time for adolescents’ motivation in school physical education.</jats:p

From ‘motivational climate’ to ‘motivational atmosphere’: a review of research examining the social and environmental influences on athlete motivation in sport

This chapter is intended to provide a comprehensive review of the various theories of social and environmental factors that influence athletes’ motivation in sport. In order to achieve this, a short historical review is conducted of the various ways in which motivation has been studied over the past 100 years, culminating in the ‘social-cognitive’ approach that undergirds several of the current theories of motivation in sport. As an outcome of this brief review, the conceptualisation and measurement of motivation are discussed, with a focus on the manner in which motivation may be influenced by key social agents in sport, such as coaches, parents and peers. This discussion leads to a review of Deci & Ryan’s (2000) self-determination theory (SDT), which specifies that environments and contexts which support basic psychological needs (competence, relatedness and autonomy) will produce higher quality motivation than environments which frustrate of exacerbate these needs. The research establishing the ways in which key social agents can support these basic needs is then reviewed, and the review depicts a situation wherein SDT has precipitated a way of studying the socio-environmental influences on motivation that has become quite piecemeal and fragmented. Following this, the motivational climate approach (Ames, 1992) specified in achievement-goals theory (AGT – Nicholls, 1989) is also reviewed. This section reveals a body of research which is highly consistent in its methodology and findings. The following two sections reflect recent debates regarding the nature of achievement goals and the way they are conceptualised (e.g., approach-avoidance goals and social goals), and the implications of this for motivational climate research are discussed. This leads to a section reviewing the current issues and concerns in the study of social and environmental influences on athlete motivation. Finally, future research directions and ideas are proposed to facilitate, precipitate and guide further research into the social and environmental influences on athlete motivation in sport. Recent studies that have attempted to address these issues are reviewed and their contribution is assessed

The motivational atmosphere in youth sport: coach, parent, and peer influences on motivation in specializing sport participants

This study qualitatively examined the motivationally relevant behaviors of key social agents in specializing sport participants. Seventy-nine participants (9-18 years old) from 26 sports participated in semi-structured focus-groups investigating how coaches, parents, and peers may influence motivation. Using a critical-realist perspective, an inductive content-analysis indicated that specializing athletes perceived a multitude of motivationally-relevant social cues. Coaches’ and parents’ influences were related to their specific roles: instruction/assessment for coaches, support-and-facilitation for parents. Peers influenced motivation through competitive behaviors, collaborative behaviors, evaluative communications, and through their social relationships. The results help to delineate different roles for social agents in influencing athletes' motivation