Scalar Matter Coupled to Quantum Gravity in the Causal Approach: Finite One-Loop Calculations and Perturbative Gauge Invariance

Quantum gravity coupled to scalar massive matter fields is investigated within the framework of causal perturbation theory. One-loop calculations include matter loop graviton self-energy and matter self-energy and yield ultraviolet finite and cutoff-free expressions. Perturbative gauge invariance to second order implies the usual Slavnov-Ward identities for the graviton self-energy in the loop graph sector and generates the correct quartic graviton-matter interaction in the tree graph sector. The mass zero case is also discussed.Comment: 37 pages, latex, no figures, some typos corrected, section 3 modifie

Silver Anniversary

Short letters about W. A. Brandenburg\u27s Silver Anniversary, written by Ed T. Hackney, Kansas Senator, and Arthur Capper. Clippings

Perturbative Noncommutative Quantum Gravity

We study perturbative noncommutative quantum gravity by expanding the gravitational field about a fixed classical background. A calculation of the one loop gravitational self-energy graph reveals that only the non-planar graviton loops are damped by oscillating internal momentum dependent factors. The noncommutative quantum gravity perturbation theory is not renormalizable beyond one loop for matter-free gravity and all loops for matter interactions. Comments are made about the nonlocal gravitational interactions produced by the noncommutative spacetime geometry.Comment: 11 pages LaTex. No figures. Changes to text. To be published in Physics Letters

Quantum gravity at a large number of dimensions

We consider the large-$D$ limit of Einstein gravity. It is observed that a consistent leading large-$D$ graph limit exists, and that it is built up by a subclass of planar diagrams. The graphs in the effective field theory extension of Einstein gravity are investigated in the same context, and it is seen that an effective field theory extension of the basic Einstein-Hilbert theory will not upset the latter leading large-$D$ graph limit, {\it i.e.}, the same subclass of planar diagrams will dominate at large-$D$ in the effective field theory. The effective field theory description of large-$D$ quantum gravity limit will be renormalizable, and the resulting theory will thus be completely well defined up to the Planck scale at $\sim 10^{19}$ GeV. The $(\frac1D)$ expansion in gravity is compared to the successful $(\frac1N)$ expansion in gauge theory (the planar diagram limit), and dissimilarities and parallels of the two expansions are discussed. We consider the expansion of the effective field theory terms and we make some remarks on explicit calculations of $n$-point functions.Comment: 18 pages, 23 figures (75 files), format RevTex4, typos corrected, references adde

Clockwork SUSY: Supersymmetric Ward and Slavnov-Taylor Identities At Work in Green's Functions and Scattering Amplitudes

We study the cancellations among Feynman diagrams that implement the Ward and Slavnov-Taylor identities corresponding to the conserved supersymmetry current in supersymmetric quantum field theories. In particular, we show that the Faddeev-Popov ghosts of gauge- and supersymmetries never decouple from the physical fields, even for abelian gauge groups. The supersymmetric Slavnov-Taylor identities provide efficient consistency checks for automatized calculations and can verify the supersymmetry of Feynman rules and the numerical stability of phenomenological predictions simultaneously.Comment: 12 pages, feynmp.sty. References added, minor typos corrected and clarified the scope of the paper in the introduction, published versio

Workplace violence in the Australian and New Zealand midwifery workforce : A scoping review

Aim The aim of the study is to identify and map what is known about workplace violence involving midwives in Australia and New Zealand. Background Research from the United Kingdom demonstrates that workplace violence within maternity services is a pervasive issue with significant and wide-ranging clinical, individual and organisational consequences. To date, little is known about this issue within Australian and New Zealand maternity services. Evaluation A scoping review, guided by Arksey and O′Malley's framework, was conducted. Reporting followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews checklist. Just one identified study aimed to explore midwives' experiences of workplace violence. A further nine arrived at related results or themes. Key issues Workplace violence is present in a variety of forms across maternity services in Australia and New Zealand. Its prevalence is, however, yet to be understood. Workplace violence causes physical and mental health issues for midwives, premature workforce attrition, and jeopardizes the quality and safety of maternity care. Conclusions Workplace violence has been acknowledged as one of the key contributing factors towards premature attrition from the midwifery profession, with new graduate midwives most likely to leave. With the midwifery workforce ageing and evidence of serious clinical implications emerging, workplace violence needs urgent research and organisational attention. Implications for nursing management Workplace violence is a key contributing factor towards recruitment and retention challenges for managers. To help tackle this, managers have a key role to play in identifying and effectively addressing workplace violence by acting as positive role models, taking a zero-tolerance approach and fostering collegial relationships. Managers, holding key clinical leadership positions, are pivotal to ensuring all complaints raised are handled with transparency and consistency regardless of one's position within the clinical hierarchy and organisational structure

Ultraviolet Complete Quantum Gravity

An ultraviolet complete quantum gravity theory is formulated in which vertex functions in Feynman graphs are entire functions and the propagating graviton is described by a local, causal propagator. The cosmological constant problem is investigated in the context of the ultraviolet complete quantum gravity.Comment: 11 pages, no figures. Changes to text. Results remain the same. References added. To be published in European Physics Journal Plu

Social media influencers' impact during pregnancy and parenting : A qualitative descriptive study

Pregnant people and parents engage with social media networking sites seeking support and information that is shared in a relatable way. Engaging with social media influencers (SMIs) and their followers, however, may have both affirming and harmful effects. SMIs can facilitate information-sharing, discussion, and supportive behaviors, but engaging with SMIs can lead to negative experiences and exposure to misinformation. To date, little is known about the impacts of following influencers during pregnancy and early parenthood. The aim of this study was to explore how engaging with SMIs impacts pregnant people and parents of children aged 5 or under in Australia. A qualitative descriptive approach was taken. Qualitative data from 85 anonymously completed online written surveys were thematically analyzed using Braun & Clarke's six-step process. Five overarching themes and two subthemes were identified. The first theme, “Comparisons of self,” held two subthemes: “Unfavorable comparisons of self to SMIs” and “Favorable comparisons of self to SMIs.” Additional themes were “A virtual community of inspiration and togetherness,” “Sharing of information, opinions & experiences,” “Gatekeeping self-efficacy,” and “Credibility.” The findings of the study indicated that discordance between influencer-mediated expectations of parenthood and a person's actual experience may affect well-being and perceptions of parental self-efficacy. Information sought from influencers may substitute for face-to-face education by clinicians. Health professionals who are also influencers may possess the ability to provide evidence-based information. This content, however, is not without risk for bias or incompleteness

Two-Loop Quark Self-Energy in a New Formalism (II): Renormalization of the Quark Propagator in the Light-Cone Gauge

The complete two-loop correction to the quark propagator, consisting of the spider, rainbow, gluon bubble and quark bubble diagrams, is evaluated in the noncovariant light-cone gauge (lcg). (The overlapping self-energy diagram had already been computed.) The chief technical tools include the powerful matrix integration technique, the n^*-prescription for the spurious poles of 1/qn, and the detailed analysis of the boundary singularities in five- and six-dimensional parameter space. It is shown that the total divergent contribution to the two-loop correction Sigma_2 contains both covariant and noncovariant components, and is a local function of the external momentum p, even off the mass-shell, as all nonlocal divergent terms cancel exactly. Consequently, both the quark mass and field renormalizations are local. The structure of Sigma_2 implies a quark mass counterterm of the form $\delta m (lcg) = m\tilde\alpha_s C_F(3+\tilde\alpha_sW) + {\rm O} (\tilde\alpha_s^3)$, \tilde\alpha_s = g^2\Gamma(\eps)(4\pi)^{\eps -2}, with W depending only on the dimensional regulator epsilon, and on the numbers of colors and flavors. It turns out that \delta m(lcg) is identical to the mass counterterm in the general linear covariant gauge. Our results are in agreement with the Bassetto-Dalbosco-Soldati renormalization scheme.Comment: 36 pages Latex, 5 eps figures, to appear in Nucl.Phys.

The impact of social media influencers on pregnancy, birth, and early parenting experiences : A systematic review

Background Pregnant and new parents are increasingly engaging with social media. The impacts of engaging with social media ‘influencers’ and ‘bloggers’ during a time of heightened vulnerability to influence, in particular, merits exploration. Aim To systematically review the literature to identify what is known about how following social media ‘influencers’ and ‘bloggers’ impacts pregnant and new parents’ experiences and decision-making. Methods A search of CINAHL, World of Science, Medline, EMBASE and Google Scholar databases was undertaken in January 2023 to identify the literature focusing on the impacts of engaging with influencers or bloggers as pregnant or new parents. The reference lists of the included papers were hand-searched. Data were extracted from each paper, tabulated, and thematically analysed. The review was reported using the 2020 Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Findings Seventeen papers met the inclusion criteria and were included in the final synthesis. Thematic analysis revealed four overarching themes, which were ‘sharing information’, ‘support’, ‘identity’, and ‘monetisation’. Discussion Social media influencers provide a network of peers amongst whom discussions, supportive behaviours, and information sharing take place. However, concern arises around the potential for combative interactions, the risk for transmission of misinformation, and the potential impacts of following influencers who are also qualified health professionals. Conclusion Existing research suggests that engaging with social media influencers can be both beneficial and harmful for pregnant and new parents. At the current time, it is unclear how exposure to the benefits or harm impacts personal experiences and decision-making