The LHC di-photon excess and Gauge Coupling Unification in Extra Z′Z^\prime Heterotic-String Derived Models

The di-photon excess observed at the LHC can be explained as a Standard Model singlet that is produced and decays by heavy vector-like colour triplets and electroweak doublets in one-loop diagrams. The characteristics of the required spectrum are well motivated in heterotic-string constructions that allow for a light $Z^\prime$. Anomaly cancellation of the $U(1)_{Z^\prime}$ symmetry requires the existence of the Standard Model singlet and vector-like states in the vicinity of the $U(1)_{Z^\prime}$ breaking scale. In this paper we show that the agreement with the gauge coupling data at one-loop is identical to the case of the Minimal Supersymmetric Standard Model, owing to cancellations between the additional states. We further show that effects arising from heavy thresholds may push the supersymmetric spectrum beyond the reach of the LHC, while maintaining the agreement with the gauge coupling data. We show that the string inspired model can indeed account for the observed signal and discuss the feasibility of obtaining viable scalar mass spectrum.Comment: 26 pages. 11 figures. Published versio

Analysing cross-cutting competencies learning in an online entrepreneurship context

Research in teaching innovation encourages leveraging the evolution of digital technologies from using the device to learning with the device, which means a change from using information and communicational technologies to learning and knowledge technologies. Nevertheless, although the feasibility of implementing active and interactive methodologies to improve education is widely recognised, more research is needed to obtain evidence on the subjects and contents with the most significant potential for success. In addition, the most recent literature claims greater attention to the improvement of transversal skills, as they are critical in the student’s professional future. Thus, the main objective of this study is to contribute to the development of immersive learning aimed at improving the cross-cutting skills of university students. Developing a teaching activity where the student acts as an entrepreneur in electronic distribution channels faces the research question. The student-company-university collaboration is the basis for enhancing the transversal skills of the Degree in Marketing and Market Research at the University of Zaragoza (Spain). The student participates in each step of the program as an active agent. The teacher tutors the work teams in each process step, and the Palbin Company provides the necessary technical support. The students give the information to analyse the success of the experience through two surveys -pre and post-workshop, following the methodology used in previous literature. While the activity planning is complex, the students show an excellent mood during the experience. The comparison between expectations and performance offers significant success from the student’s point of view. As a result, the student improves cross-cutting competencies and gains confidence, satisfaction with their learning at university, and professional experience

Wilsonian dark matter in string derived Z' model

The dark matter issue is among the most perplexing in contemporary physics. The problem is more enigmatic due to the wide range of possible solutions, ranging from the ultra-light to the super-massive. String theory gives rise to plausible dark matter candidates due to the breaking of the non--Abelian Grand Unified Theory (GUT) symmetries by Wilson lines. The physical spectrum then contains states that do not satisfy the quantisation conditions of the unbroken GUT symmetry. Given that the Standard Model states are identified with broken GUT representations, and provided that any ensuing symmetry breaking is induced by components of GUT states, leaves a remnant discrete symmetry that forbid the decay of the Wilsonian states. A class of such states are obtained in a heterotic-string derived $Z^\prime$ model. The model exploits the spinor-vector duality symmetry, observed in the fermionic $Z_2\times Z_2$ heterotic-string orbifolds, to generate a $Z^\prime\in E_6$ symmetry that may remain unbroken down to low energies. The $E_6$ symmetry is broken at the string level with discrete Wilson lines. The Wilsonian dark matter candidates in the string derived model are $SO(10)$, and hence Standard Model, singlets and possess non-$E_6$ $U(1)_{Z^\prime}$ charges. Depending on the $U(1)_{Z^\prime}$ breaking scale and the reheating temperature they give rise to different scenarios for the relic abundance, and in accordance with the cosmological constraints.Comment: 24 pages. 5 figures. Standard LaTex. Additional comments and clarifications. Published versio

Wilsonian Dark Matter in String Derived Z′Z^\prime Model

The dark matter issue is among the most perplexing in contemporary physics. The problem is more enigmatic due to the wide range of possible solutions, ranging from the ultra-light to the super-massive. String theory gives rise to plausible dark matter candidates due to the breaking of the non--Abelian Grand Unified Theory (GUT) symmetries by Wilson lines. The physical spectrum then contains states that do not satisfy the quantisation conditions of the unbroken GUT symmetry. Given that the Standard Model states are identified with broken GUT representations, and provided that any ensuing symmetry breaking is induced by components of GUT states, leaves a remnant discrete symmetry that forbid the decay of the Wilsonian states. A class of such states are obtained in a heterotic-string derived $Z^\prime$ model. The model exploits the spinor-vector duality symmetry, observed in the fermionic $Z_2\times Z_2$ heterotic-string orbifolds, to generate a $Z^\prime\in E_6$ symmetry that may remain unbroken down to low energies. The $E_6$ symmetry is broken at the string level with discrete Wilson lines. The Wilsonian dark matter candidates in the string derived model are $SO(10)$, and hence Standard Model, singlets and possess non-$E_6$ $U(1)_{Z^\prime}$ charges. Depending on the $U(1)_{Z^\prime}$ breaking scale and the reheating temperature they give rise to different scenarios for the relic abundance, and in accordance with the cosmological constraints

Network polarization, filter bubbles, and echo chambers: An annotated review of measures and reduction methods

Polarization arises when the underlying network connecting the members of a community or society becomes characterized by highly connected groups with weak inter-group connectivity. The increasing polarization, the strengthening of echo chambers, and the isolation caused by information filters in social networks are increasingly attracting the attention of researchers from different areas of knowledge such as computer science, economics, social and political sciences. This work presents an annotated review of network polarization measures and models used to handle the polarization. Several approaches for measuring polarization in graphs and networks were identified, including those based on homophily, modularity, random walks, and balance theory. The strategies used for reducing polarization include methods that propose edge or node editions (including insertions or deletions, as well as edge weight modifications), changes in social network design, or changes in the recommendation systems embedded in these networks.Comment: Corrected a typo in Section 3.2; the rest remains unchange

Acoustic levitation in mid-air: recent advances, challenges, and future perspectives

Mid-air acoustic levitation is becoming a powerful tool to suspend and manipulate millimetric objects. Because of its unique characteristics, acoustic levitation is suitable to trap a wide variety of materials such as liquids, solids, soap bubbles, and even living creatures. Acoustic levitation can also be combined with noncontact measurement systems, allowing contactless analysis and characterization of levitating samples. In this article, we review some of the advances that have been made over the last decade. We also present the technical challenges that must be overcome in order to extend the capability of current acoustic levitation devices and, finally, we point out future directions for acoustic levitation.This work was supported by the São Paulo Research Foundation–FAPESP (Grant No. 2017/27078-0) and by the Government of Navarre through Fondo Europeo de Desarrollo Regional (FEDER) Project No. 0011-1365-2019-000086

Anomalous prompt photon production in hadronic collisions at low-xTx_T

We investigate the discrepancy that exists at low-$x_T=2p_T/\sqrt{s}$ between the next--to--leading order QCD calculations of prompt photon production and the measured cross section. The central values of the measured cross section are of order 100\% larger than QCD predictions in this region. It has been suggested that the bremsstrahlung contribution may account for this discrepancy. The quark fragmentation function $D_{\gamma/q}(z)$ has not been measured and an exactly known asymptotic form is normally used in calculations. We examine the effect of much larger fragmentation functions on the QCD predictions. After illustrating the effect of the large fragmentation functions in some detail for recent CDF data at $\sqrt{s}$=1.8~TeV, we perform a $\chi^2$ fit to 8 prompt photon data sets ranging in CMS energy from 24~GeV to 1.8~TeV. While a large fragmentation function normalization may prove to play an important role in resolving the discrepancy, the present theoretical and experimental uncertainties prevent any definite normalization value from being determined.Comment: 14 pages, LBL-33122 and UCB-PTH-92/38. 13 figures available by email, specify postscript or topdrawe

New metabolically stable fatty acid amide ligands of cannabinoid receptors: synthesis and receptor affinity studies

We investigated the structure-activity relationships for the interactions of fatty acid amide analogs of the endocannabinoid anandamide with human recombinant cannabinoid receptors. Thirty-five novel fatty acid amides were synthesized using five different types of acyl chains and 11 different aromatic amine 'heads.' Although none of the new compounds was a more potent ligand than anandamide, we identified three amine groups capable of improving the metabolic stability of arachidonoylamides and their CBI/CB2 selectivity ratio to over 20-fold, and several aromatic amines capable of improving the affinity of short chain or monosaturated fatty acids for cannabinoid CBI receptors. For the first time a tertiary amide of arachidonic acid was found to possess moderate affinity (K, = 300 nM) for cannabinoid CBI, but not CB2, receptors

Hidden in plain sight: is there a crucial role for enthesitis assessment in the treatment and monitoring of axial spondyloarthritis?

OBJECTIVE: To review the evidence surrounding the pathophysiology of enthesitis in axial spondyloarthritis (axSpA), its prevalence and contribution to the overall disease burden, and response to treatment at axial and peripheral sites. METHODS: Literature searches of the Cochrane Library, PubMed, and Embase / Medline using the terms “enthesitis“, “enthesopathy”, “spondyloarthritis”, “axial spondyloarthritis”, and “ankylosing spondylitis” were conducted. Publications mentioning enthesitis or enthesopathy in the context of pathophysiology, diagnosis, or treatment were included. RESULTS: Enthesitis is a common symptom of axSpA, occurring with high prevalence at axial and several peripheral sites. Inflammation at the site of enthesis is an early key manifestation of axSpA. Clinically evaluable enthesitis contributes significantly to the burden of disease, correlating with worse symptomatology and downstream structural damage. Despite its importance in driving axSpA disease processes, enthesitis is somewhat neglected in current approaches to disease assessment and management. Enthesitis is excluded from some commonly used disease activity measures, is not routinely assessed in clinical practice, and many methods of clinical assessment omit key accessible axial sites, such as the spinous processes. CONCLUSION: Enthesitis plays a central role in driving the pathophysiology of axSpA. There is a need for a renewed focus on the early detection, measurement and treatment of enthesitis