Conformal constraints for anomalous dimensions of leading twist operators

Leading-twist operators have a remarkable property that their divergence vanishes in a free theory. Recently it was suggested that this property can be used for an alternative technique to calculate anomalous dimensions of leading-twist operators and allows one to gain one order in perturbation theory so that, i.e., two-loop anomalous dimensions can be calculated from one-loop Feynman diagrams, etc. In this work we study feasibility of this program on a toy-model example of the $\varphi^3$ theory in six dimensions. Our conclusion is that this approach is valid, although it does not seem to present considerable technical simplifications as compared to the standard technique. It does provide one, however, with a very nontrivial check of the calculation as the structure of the contributions is very different.Comment: 14 pages, 6 figure

Two-loop conformal generators for leading-twist operators in QCD

QCD evolution equations in minimal subtraction schemes have a hidden symmetry: One can construct three operators that commute with the evolution kernel and form an $SL(2)$ algebra, i.e. they satisfy (exactly) the $SL(2)$ commutation relations. In this paper we find explicit expressions for these operators to two-loop accuracy going over to QCD in non-integer $d=4-2\epsilon$ space-time dimensions at the intermediate stage. In this way conformal symmetry of QCD is restored on quantum level at the specially chosen (critical) value of the coupling, and at the same time the theory is regularized allowing one to use the standard renormalization procedure for the relevant Feynman diagrams. Quantum corrections to conformal generators in $d=4-2\epsilon$ effectively correspond to the conformal symmetry breaking in the physical theory in four dimensions and the $SL(2)$ commutation relations lead to nontrivial constraints on the renormalization group equations for composite operators. This approach is valid to all orders in perturbation theory and the result includes automatically all terms that can be identified as due to a nonvanishing QCD $\beta$-function (in the physical theory in four dimensions). Our result can be used to derive three-loop evolution equations for flavor-nonsinglet quark-antiquark operators including mixing with the operators containing total derivatives. These equations govern, e.g., the scale dependence of generalized hadron parton distributions and light-cone meson distribution amplitudes.Comment: 36 page

Electroproduction of tensor mesons in QCD

Due to multiple possible polarizations hard exclusive production of tensor mesons by virtual photons or in heavy meson decays offers interesting possibilities to study the helicity structure of the underlying short-distance process. Motivated by the first measurement of the transition form factor $\gamma^*\gamma \to f_2(1270)$ at large momentum transfers by the BELLE collaboration we present an improved QCD analysis of this reaction in the framework of collinear factorization including contributions of twist-three quark-antiquark-gluon operators and an estimate of soft end-point corrections using light-cone sum rules. The results appear to be in a very good agreement with the data, in particular the predicted scaling behavior is reproduced in all cases.Comment: 27 pages, 5 figure

End User Perception and Software Quality Assessment

The topic of software quality assessment is at the forefront of the software engineering movement. Many models of organization and quality control exist which serve to foster software quality and reliability (Bloom, McPheters & Tsiang, 1973; Brandl, 1990; Comer, 1988; Dunn, 1990; Kaplan, Clark & Tang, 1994; Livson, 1988; Musa, lannino & Okumoto, 1987). Some models now consider the software engineering project team and end users, but most still treat them as static contributors to the system. Major factors often ignored in most conventional models include the cybernetics of the process, and human factors which have a significant impact on the assessment of the quality of the software. Software environment, adaptability, and motivation have all been discussed as essential in creating a superior product. Yet, the factor of human perception has been either overlooked or avoided in the ensuing discussions. In software development the software engineers\u27 perceptions as well as those of all potential end users, must be considered in order to ensure software quality and reliability.End User Perception and Software Quality Assessmen

A comparison of self-reports and electrodermal activity as indicators of mathematics state anxiety.: An application of the control-value theory

In the present study with 86 undergraduate students, we related trait Mathematics Anxiety (MA) with two indicators of state anxiety: self-reported state anxiety and electrodermal activity (EDA). Extending existing research, we included appraisals of control and perceived value in hierarchical multiple regression analyses in accordance with the control-value theory of achievement emotions (Pekrun, 2006). Results showed that trait MA predicted self-reported state anxiety, while no additional variance was explained by including control and value. In contrast, we found no significant relation between trait MA and physiological state anxiety, but a significant, negative three-way interaction effect with control and value. Regression coefficients indicated that trait MA predicted physiological state anxiety, but only in the presence of negative perceived control and positive perceived value. Thus, our results support the control-value theory for physiological state anxiety, but not for self-reports. They emphasize the need to distinguish between trait and state MA, the advantages of adopting the control-value theory, and the benefits of using EDA recording as a supplemental assessment method for state anxiety

Methoden der lexikalischen Nachkorrektur OCR-erfasster Dokumente

Das maschinelle Lesen, d. h. die Umwandlung gedruckter Dokumente via Pixelrepräsentation in eine Symbolfolgen, erfolgt mit heute verfügbaren, kommerziellen OCR-Engines für viele Dokumentklassen fast schon fehlerfrei. Trotzdem gilt für die meisten OCR-Anwendungen die Devise, je weniger Fehler, desto besser. Beispielsweise kann ein falsch erkannter Name innerhalb eines Geschäftsbriefes in einem automatisierten System zur Eingangsspostverteilung unnötige Kosten durch Fehlzuordnungen o.ä. verursachen. Eine lexikalische Nachkorrektur hilft, verbleibende Fehler von OCR-Engines aufzuspüren, zu korrigieren oder auch mit einer interaktiven Korrektur zu beseitigen. Neben einer Realisierung als nachgelagerte, externe Komponente, kann eine lexikalische Nachkorrektur auch direkt in eine OCR-Engine integriert werden. Meinen Beitrag zur lexikalischen Nachkorrektur habe ich in zehn Thesen untergliedert: These T1: Für eine Nachkorrektur von OCR-gelesenen Fachtexten können Lexika, die aus thematisch verwandten Web-Dokumenten stammen, gewinnbringend eingesetzt werden. These T2: Das Vokabular eines Fachtexts wird von großen Standardlexika unzureichend abgedeckt. Durch Textextraktion aus thematisch verwandten Web-Dokumenten lassen sich Lexika mit einer höheren Abdeckungsrate gewinnen. Zudem spiegeln die Frequenzinformationen aus diesen Web-Dokumenten die des Fachtexts besser wider als Frequenzinformationen aus Standardkorpora. These T3: Automatisierte Anfragen an Suchmaschinen bieten einen geeigneten Zugang zu den einschlägigen Web-Dokumenten eines Fachgebiets. These T4: Eine feingliedrige Fehlerklassifikation erlaubt die Lokalisierung der beiden Hauptfehlerquellen der webgestützten Nachkorrektur: • falsche Freunde, d. h. Fehler, die unentdeckt bleiben, da sie lexikalisch sind • unglückliche Korrekturen hin zu Orthographie- oder Flexions-Varianten These T5: Falsche Freunde werden durch eine Kombination mehrerer OCR-Engines deutlich vermindert. These T6: Mit einfachen Heuristiken wird ein unglücklicher Variantenaustausch der Nachkorrekturkomponente vermieden. These T7: Mit einer Vereinheitlichung zu Scores lassen sich diverse OCR-Nachkorrekturhilfen wie etwa Wort-Abstandsmaße, Frequenz- und Kontextinformationen kombinieren und zur Kandidaten- sowie Grenzbestimmung einsetzen. These T8: OCR-Nachkorrektur ist ein multidimensionales Parameteroptimierungsproblem, wie z. B. Auswahl der Scores, deren Kombination und Gewichtung, Grenzbestimmung oder Lexikonauswahl. Eine graphische Oberfläche eignet sich für eine Untersuchung der Parameter und deren Adjustierung auf Trainingsdaten. These T9: Die Software zur Parameteroptimierung der Nachkorrektur der Resultate einer OCR-Engine kann für die Kombination mehrerer OCR-Engines wiederverwendet werden, indem die Einzelresultate der Engines wieder zu Scores vereinheitlicht werden. These T10: Eine Wort-zu-Wort-Alignierung, wie sie für die Groundtruth-Erstellung und die Kombination von OCR-Engines notwendig ist, kann durch eine Verallgemeinerung des Levenshtein-Abstands auf Wortebene effizient realisiert werden

Co-creativity, well-being and agency: a case study analysis of a co-creative arts group for people with dementia

At the heart of this paper is an exploration of artistic co-creativity involving people with dementia and their partners. Co-creativity promotes a relational approach to creativity which nurtures inclusion and participation. This paper investigates how co-creativity can affect well-being from the perspectives of people with dementia and their carers; and explores how well-being and agency might be usefully reconsidered. The article draws on findings from a small-scale study ‘With All’ that focused on music and dance as non-verbal and therefore inclusive artforms. A range of disciplinary perspectives, from psychology, philosophy and social sciences, inform the study. The research used an intrinsic case-study methodology and within this a mixed-methods approach was adopted. This included dialogic interviews, video data analysis and the Canterbury Well-being Scale (CWS). Thematic analysis of the interviews and video data revealed three key themes: autonomy, connections, and art as an enabler. These themes captured the experiences of the participants and facilitated a more nuanced understanding of wellbeing and agency in the context of living with dementia. The analysis of the CWS indicated some improvements in well-being. Following this analysis using multiple data sources, the paper argues that wellbeing and agency are best understood as relational, and ongoing, rather than completed states. Further both wellbeing and agency contain their opposites (ill-being and passivity). This innovative exploration highlighted the importance of co-creative collaboration as a method that was considered valuable by participants, and that therefore should be further considered in future research with people living with dementia