Top Quark Charge Asymmetry: Searching for Light Axigluons in top pair + jet Production at the LHC

We investigate the discovery potential of light color-octet bosons in the mass range of 100 - 400 GeV in exclusive top-pair plus jet production at the LHC. We study the impact of such bosons on the incline, the energy and the rapidity asymmetries. We show that light axigluons with large couplings to quarks can be discovered at the LHC with a luminosity of a few inverse fb. Almost all of the considered axigluon parameter space can be probed using the already available 2011/2012 LHC data. In a small-coupling scenario, axigluons could be discovered using the charge asymmetry with 65 inverse fb at the LHC and a center of mass energy of 14 TeV. We furthermore show that top pair+jet production could reveal the existence of scenarios where axigluons couple with a different strength to up- and down-type quarks.Comment: 25 pages, 11 figures, 1 tabl

Effective Theory for a Heavy Scalar Coupled to the SM via Vector-Like Quarks

We illustrate the application of the recently developed SCET$_{\rm BSM}$ framework in the context of a specific model, in which the Standard Model (SM) is supplemented by a heavy scalar $S$ and three generations of heavy, vector-like quarks $\Psi$. We construct the appropriate effective field theory for two-body decays of $S$ into SM particles. We explicitly compute the Wilson coefficients of the SCET$_{\rm BSM}$ operators appearing at leading and next-to-leading order (NLO) in an expansion in powers of $v/M_S$, as well as for a subset of operators arising at NNLO, retaining the full dependence on the ratio $M_S/M_\Psi$. For the phenomenologically most relevant decay channels of the heavy scalar, we study the impact of resummation effects of Sudakov logarithms on the decay rates.Comment: 11 pages, 6 figure

Consistent Searches for SMEFT Effects in Non-Resonant Dijet Events

We investigate the bounds which can be placed on generic new-physics contributions to dijet production at the LHC using the framework of the Standard Model Effective Field Theory, deriving the first consistently-treated EFT bounds from non-resonant high-energy data. We recast an analysis searching for quark compositeness, equivalent to treating the SM with one higher-dimensional operator as a complete UV model. In order to reach consistent, model-independent EFT conclusions, it is necessary to truncate the EFT effects consistently at order $1/\Lambda^2$ and to include the possibility of multiple operators simultaneously contributing to the observables, neither of which has been done in previous searches of this nature. Furthermore, it is important to give consistent error estimates for the theoretical predictions of the signal model, particularly in the region of phase space where the probed energy is approaching the cutoff scale of the EFT. There are two linear combinations of operators which contribute to dijet production in the SMEFT with distinct angular behavior; we identify those linear combinations and determine the ability of LHC searches to constrain them simultaneously. Consistently treating the EFT generically leads to weakened bounds on new-physics parameters. These constraints will be a useful input to future global analyses in the SMEFT framework, and the techniques used here to consistently search for EFT effects are directly applicable to other off-resonance signals.Comment: v1: 23 pages, 9 figures, 3 tables; v2: references added, typos corrected, matches version published in JHE

Exclusive Radiative Decays of Z Bosons in QCD Factorization

We discuss the very rare, exclusive hadronic decays of a Z boson into a meson and a photon. The QCD factorization approach allows to organize the decay amplitude as an expansion in powers of $\Lambda_{\rm QCD}/m_Z\,$, where the leading terms contain convolutions of perturbatively calculable hard functions with the leading-twist light-cone distribution amplitudes of the meson. We find that power corrections to these leading terms are negligible since they are suppressed by the small ratio $(\Lambda_{\rm QCD}/m_Z)^2\,$. Renormalization-group effects play a crucial role as they render our theoretical predictions less sensitive to the hadronic input parameters which are currently not known very precisely. Thus, measurements of the decays $Z\to M\gamma$ at the LHC or a future lepton collider provide a theoretically very clean way to test the QCD factorization approach. The special case where $M=\eta^({}'{}^)$ is complicated by the fact that the decay amplitude receives an additional contribution where the meson is formed from a two-gluon state. The corresponding branching ratios are very sensitive to the hadronic parameters describing the $\eta-\eta'$ system. Future measurements of these decays could yield interesting information about these parameters and the gluon distribution amplitude.Comment: 6 pages, 3 figures, 1 table, contribution to the proceedings of the 38th International Conference on High Energy Physics, 3-10 August 2016, Chicago, US

Consistent Searches for SMEFT Effects in Non-Resonant Dilepton Events

Employing the framework of the Standard Model Effective Field Theory, we perform a detailed reinterpretation of measurements of the Weinberg angle in dilepton production as a search for new-physics effects. We truncate our signal prediction at order $1/\Lambda^2$, where $\Lambda$ denotes the new-physics mass scale, and introduce a theory error to account for unknown contributions of order $1/\Lambda^4$. Two linear combinations of four-fermion operators with distinct angular behavior contribute to dilepton production with growing impact at high energies. We define suitable angular observables and derive bounds on those two linear combinations using data from the Tevatron and the LHC. We find that the current data is able to constrain interesting regions of parameter space, with important contributions at lower cutoff scales from the Tevatron, and that the future LHC data will eventually be able to simultaneously constrain both independent linear combinations which contribute to dilepton production.Comment: 11 pages, 4 figures v2: updated to match version accepted for publicatio

Art on Instagram : the impact of art-related content on followers’ and artists´self-perception of creativity

Because Instagram is such a visually oriented social media platform, it is vital to understand the influence that it may have on its users' perceptions of their own creative abilities and potential. In part because of its scale, many artists now consider that their presence on the platform is mandatory; yet, the network has also offered art enthusiasts an unparalleled opportunity to get closer to these artists and their work. The purpose of this dissertation is to investigate the impact of art-related accounts on Instagram on artists and other followers who are not professional artists, especially in terms of their creativity. During the research, semi-structured interviews with artists who use Instagram were conducted, as well as focus groups with individuals who follow art-related accounts on the social media platform. The findings revealed that both artists and the followers agree that consuming artrelated content on Instagram has significant potential to aid in the creative and inspirational process. While the artists and non-artist followers’ motivations differ in a few ways, which are primarily related to artists' views of the platform as a tool for promoting and improving their work, and followers' views of the platform as a source of entertainment or distraction, they also share some motivations for following art-related content. The results also concluded that there were possible negative consequences on creativity, such as comparison and anxiety, that eventually discouraged artists, even while many were able to get creative inspiration on Instagram

The Role of Macrophytes in Constructed Surface-flow Wetlands for Mine Water Treatment : A Review

<jats:title>Abstract</jats:title><jats:p>Constructed wetlands are a standard sustainable technology in waste and mine water treatment. Whereas macrophytes actively contribute to decomposition and/or removal of wastewater’s organic pollutants, removal of hydrolysable metals from mine water is not attributable to direct metabolic, but rather various indirect macrophyte-related mechanisms. These mechanisms result in higher treatment efficiency of (vegetated) wetlands relative to (unvegetated) settling ponds. Contribution of macrophytes to treatment predominantly includes: enhanced biogeochemical oxidation and precipitation of hydrolysable metals due to catalytic reactions and bacterial activity, particularly on immersed macrophyte surfaces; physical filtration of suspended hydrous ferric oxides by dense wetland vegetation down to colloids that are unlikely to gravitationally settle efficiently; scavenging and heteroaggregation of dissolved and colloidal iron, respectively, by plant-derived natural organic matter; and improved hydrodynamics and hydraulic efficiency, considerably augmenting retention and exposure time. The review shows that constructed surface-flow wetlands have considerable advantages that are often underestimated. In addition to treatment enhancement, there are socio-environmental benefits such as aesthetic appearance, biotope/habitat value, and landscape diversity that need to be considered. However, there is currently no quantitative, transferrable approach to adequately describe the effect and magnitude of macrophyte-related benefits on mine water amelioration, let alone clearly assign optimal operational deployment of either settling ponds or wetlands. A better (quantitative) understanding of underlying processes and kinetics is needed to optimise assembly and sizing of settling ponds and wetlands in composite passive mine water treatment systems.</jats:p&gt

How can food providers improve their business models In order to increase a sustainable consumption?

In the current business environment, the concern with sustainability and food waste has gained high notoriety. Companies, in this case, restaurants, demonstrate, in fact, a concern with this issue and assume it to be a problem that needs to be solved or, at least, minimized. This research demonstrates the importance of innovation in the business models in order to become more sustainable and also presents some solutions and suggestions of strategies to be applied in the restaurant sector. Following a set of interviews carried out with professionals in positions of high responsibility in the catering industry, the results reveal that, although sustainability is on the management's mind, there is still little information in terms of strategies and tools that they can adopt in their day-to-day work. They already execute some of these strategies, but there is still a way to go. On the other hand, the consumer is often the motivating agent that leads companies to act in a certain way, and according to the interviewees, their customers are not yet aware of the need to solve this problem, which becomes a major barrier. From a general perspective, companies should educate consumers and should also seek more information in order to complete or restructure their strategies with the aim of becoming exemplary agents that promote responsible attitudes aimed at improving the planet.No atual ambiente empresarial, a preocupação com a sustentabilidade e com o desperdício alimentar tem ganho elevada notoriedade. As empresas, neste caso, restaurantes demonstram, de facto, uma preocupação com este tema e assumem ser um problema que precisa de ser resolvido ou, pelo menos, minimizado. Esta investigação demonstra a importância da inovação nos modelos de negócio de forma a tornarem-se mais sustentáveis e apresenta ainda algumas soluções e sugestões de estratégias a aplicar no setor da restauração. Na sequência de um conjunto de entrevistas realizadas a profissionais com posições de elevada responsabilidade no ceio da restauração, os resultados revelam que, embora a sustentabilidade esteja na mente de gestão, ainda existe pouca informação em termos de estratégias e ferramentas que podem adotar no seu dia-a-dia. Já executam algumas dessas estratégias, mas há ainda um caminho a percorrer. Por outro lado, o consumidor é, muitas vezes, o agente de motivação que leva as empresas a agir de determinada forma, e de acordo com os entrevistados, os seus clientes ainda não estão mentalizados para a necessidade de resolução deste problema, o que se torna numa grande barreira. Numa perspetiva geral, as empresas devem educar os consumidores e devem ainda procurar mais informação de forma a completarem ou reestruturarem as suas estratégias com o objetivo de se tornarem exemplares agentes fomentadores de atitudes responsáveis que visem uma melhoria do planeta