Composite Operators in the Twistor Formulation of N=4\mathcal{N}=4 SYM Theory

We incorporate gauge-invariant local composite operators into the twistor-space formulation of $\mathcal{N}=4$ Super Yang-Mills theory. In this formulation, the interactions of the elementary fields are reorganized into infinitely many interaction vertices and we argue that the same applies to composite operators. To test our definition of the local composite operators in twistor space, we compute several corresponding form factors, thereby also initiating the study of form factors using the position twistor-space framework. Throughout this letter, we use the composite operator built from two identical complex scalars as a pedagogical example; we treat the general case in a follow-up paper.Comment: letter, 5 pages, 1 figur

Can selective attention and inhibition (interactively) predict future obsessive compulsive symptoms? A prospective study

Background and objectives: The current study set out to investigate whether obsessive beliefs, selective attention, inhibition, and the interaction between selective attention and inhibition can prospectively predict contamination obsessive compulsive (OC) symptoms. Methods: Obsessive beliefs, inhibition, and selective attention were assessed in a student sample (n = 89) during a baseline session in the beginning of the first semester. Their predictive value was examined by assessing symptoms after an OC symptom induction in the lab and by assessing OC symptoms during a period of increased stress (the examination period) 68-80 days after baseline. Results: Results showed that obsessive beliefs did not consistently predict OC symptoms and there was no predictive effect of attentional bias, attentional bias variability, and inhibition in isolation. However, attentional bias variability and inhibition in the context of contamination -related stimuli interacted, in which only the combination of poor inhibition and large attentional bias variability predicted contamination OC symptoms during the examination period. Limitations: Future research should investigate whether similar results are found in clinical populations, as the current sample consisted of a convenience sample of undergraduate students. Conclusion: These results support the notion that information processing biases interact in predicting contamination OC symptoms

A Twistorial Approach to Integrability in N=4 SYM

While the achievements in the study of N=4 Super Yang-Mills through the application of integrability are impressive, the precise origins of the exact solvability remain shrouded in mystery. In this note, we propose that viewing the problem through the lens of twistor theory should help to clarify the reasons for integrability. We illustrate the power of this approach by rederiving the model's one-loop spin chain dilatation operator in the SO(6) sector.Comment: 10 pages, 2 figures. This is the accepted version that has been published in Fortschritte der Physik 63, No. 2, 142-147 (2015

On form factors and correlation functions in twistor space

In this paper, we continue our study of form factors and correlation functions of gauge-invariant local composite operators in the twistor-space formulation of N=4 super Yang-Mills theory. Using the vertices for these operators obtained in our recent papers arXiv:1603.04471 and arXiv:1604.00012, we show how to calculate the twistor-space diagrams for general N^kMHV form factors via the inverse soft limit, in analogy to the amplitude case. For general operators without $\dot\alpha$ indices, we then reexpress the NMHV form factors from the position-twistor calculation in terms of momentum twistors, deriving and expanding on a relation between the two twistor formalisms previously observed in the case of amplitudes. Furthermore, we discuss the calculation of generalized form factors and correlation functions as well as the extension to loop level, in particular providing an argument promised in arXiv:1410.6310.Comment: 24+17 pages, 18 figures; v2: typos corrected, matches published versio

Enhanced C/EBPβ function promotes hypertrophic versus hyperplastic fat tissue growth and prevents steatosis in response to high-fat diet feeding

Chronic obesity is correlated with severe metabolic and cardiovascular diseases as well as with an increased risk for developing cancers. Obesity is usually characterized by fat accumulation in enlarged-hypertrophic – adipocytes that are a source of inflammatory mediators, which promote the development and progression of metabolic disorders. Yet, in certain healthy obese individuals, fat is stored in metabolically more favorable hyperplastic fat tissue that contains an increased number of smaller adipocytes that are less inflamed. In a previous study we demonstrated that loss of the inhibitory protein-isoform C/EBPβ-LIP and the resulting augmented function of the transactivating isoform C/EBPβ-LAP promotes fat metabolism under normal feeding conditions and expands health-and lifespan in mice. Here we show that in mice on a high-fat diet, LIP-deficiency results in adipocyte hyperplasia associated with reduced inflammation and metabolic improvements. Furthermore, fat storage in subcutaneous depots is significantly enhanced specifically in LIP-deficient male mice. Our data identify C/EBPβ as a regulator of adipocyte fate in response to increased fat intake, which has major implications for metabolic health and aging