Spontaneous Symmetry Breaking at Infinite Momentum without P+ Zero-Modes

The nonrelativistic interpretation of quantum field theory achieved by quantization in an infinite momentum frame is spoiled by the inclusion of a mode of the field carrying p+=0. We therefore explore the viability of doing without such a mode in the context of spontaneous symmetry breaking (SSB), where its presence would seem to be most needed. We show that the physics of SSB in scalar quantum field theory in 1+1 space-time dimensions is accurately described without a zero-mode.Comment: LaTeX, 8 pages, 3 eps figure

Quantum Newtonian Dynamics on a Light Front

We recall the special features of quantum dynamics on a light-front (in an infinite momentum frame) in string and field theory. The reason this approach is more effective for string than for fields is stressed: the light-front dynamics for string is that of a true Newtonian many particle system, since a string bit has a fixed Newtonian mass. In contrast, each particle of a field theory has a variable Newtonian mass P^+, so the Newtonian analogy actually requires an infinite number of species of elementary Newtonian particles. This complication substantially weakens the value of the Newtonian analogy in applying light-front dynamics to nonperturbative problems. Motivated by the fact that conventional field theories can be obtained as infinite tension limits of string theories, we propose a way to recast field theory as a standard Newtonian system. We devise and analyze some simple quantum mechanical systems that display the essence of the proposal, and we discuss prospects for applying these ideas to large N_c QCD.Comment: 13 pages, 3 figures, LaTex, psfig, references added, APS copyrigh

1+11+1-Dimensional Large NN QCD coupled to Adjoint Fermions

We consider 1+1-dimensional QCD coupled to Majorana fermions in the adjoint representation of the gauge group $SU(N)$. Pair creation of partons (fermion quanta) is not suppressed in the large-$N$ limit, where the glueball-like bound states become free. In this limit the spectrum is given by a linear \lc\ Schr\" odinger equation, which we study numerically using the discretized \lcq. We find a discrete spectrum of bound states, with the logarithm of the level density growing approximately linearly with the mass. The wave function of a typical excited state is a complicated mixture of components with different parton numbers. A few low-lying states, however, are surprisingly close to being eigenstates of the parton number, and their masses can be accurately calculated by truncated diagonalizations.Comment: 22 pages + 9 figures (available by request from [email protected]), uses phyzzx.tex + tables.tex PUPT-1413, IASSNS-HEP-93/4

From Free Fields to AdS -- II

We continue with the program of hep-th/0308184 to implement open-closed string duality on free gauge field theory (in the large $N$ limit). In this paper we consider correlators such as \la \prod_{i=1}^n \Tr\Phi^{J_i}(x_i)\ra. The Schwinger parametrisation of this $n$-point function exhibits a partial gluing up into a set of basic skeleton graphs. We argue that the moduli space of the planar skeleton graphs is exactly the same as the moduli space of genus zero Riemann surfaces with $n$ holes. In other words, we can explicitly rewrite the $n$-point (planar) free field correlator as an integral over the moduli space of a sphere with $n$ holes. A preliminary study of the integrand also indicates compatibility with a string theory on $AdS$. The details of our argument are quite insensitive to the specific form of the operators and generalise to diagrams of higher genus as well. We take this as evidence of the field theory's ability to reorganise itself into a string theory.Comment: 26 pages, 2 figures; v2. some additional comments, references adde

Fine-Tuning Renormalization and Two-particle States in Nonrelativistic Four-fermion Model

Various exact solutions of two-particle eigenvalue problems for nonrelativistic contact four-fermion current-current interaction are obtained. Specifics of Goldstone mode is investigated. The connection between a renormalization procedure and construction of self-adjoint extensions is revealed.Comment: 13 pages, LaTex, no figures, to be published in IJMP

Qualitative research within trials: developing a standard operating procedure for a clinical trials unit

<p>BACKGROUND: Qualitative research methods are increasingly used within clinical trials to address broader research questions than can be addressed by quantitative methods alone. These methods enable health professionals, service users, and other stakeholders to contribute their views and experiences to evaluation of healthcare treatments, interventions, or policies, and influence the design of trials. Qualitative data often contribute information that is better able to reform policy or influence design.</p> <p>METHODS: Health services researchers, including trialists, clinicians, and qualitative researchers, worked collaboratively to develop a comprehensive portfolio of standard operating procedures (SOPs) for the West Wales Organisation for Rigorous Trials in Health (WWORTH), a clinical trials unit (CTU) at Swansea University, which has recently achieved registration with the UK Clinical Research Collaboration (UKCRC). Although the UKCRC requires a total of 25 SOPs from registered CTUs, WWORTH chose to add an additional qualitative-methods SOP (QM-SOP).</p> <p>RESULTS: The qualitative methods SOP (QM-SOP) defines good practice in designing and implementing qualitative components of trials, while allowing flexibility of approach and method. Its basic principles are that: qualitative researchers should be contributors from the start of trials with qualitative potential; the qualitative component should have clear aims; and the main study publication should report on the qualitative component.</p> <p>CONCLUSIONS: We recommend that CTUs consider developing a QM-SOP to enhance the conduct of quantitative trials by adding qualitative data and analysis. We judge that this improves the value of quantitative trials, and contributes to the future development of multi-method trials.</p&gt

A Review of Symmetry Algebras of Quantum Matrix Models in the Large-N Limit

This is a review article in which we will introduce, in a unifying fashion and with more intermediate steps in some difficult calculations, two infinite-dimensional Lie algebras of quantum matrix models, one for the open string sector and one for the closed string sector. Physical observables of quantum matrix models in the large-N limit can be expressed as elements of these Lie algebras. We will see that both algebras arise as quotient algebras of a larger Lie algebra. We will also discuss some properties of these Lie algebras not published elsewhere yet, and briefly review their relationship with well-known algebras like the Cuntz algebra, the Witt algebra and the Virasoro algebra. We will also review how Yang--Mills theory, various low energy effective models of string theory, quantum gravity, string-bit models, and quantum spin chain models can be formulated as quantum matrix models. Studying these algebras thus help us understand the common symmetry of these physical systems.Comment: 77 pages, 21 eps figures, 1 table, LaTeX2.09; an invited review articl

Resource recovery from the anaerobic digestion of food waste is underpinned by cross-kingdom microbial activities

This work was supported by the Earth and Natural Sciences (ENS) Doctoral Studies Programme, funded by the Higher Education Authority (HEA) of Ireland through the Programme for Research at Third Level Institutions, Cycle 5 (PRTLI-5), co-funded by the European Regional Development Fund (ERDF).As the human population grows on the planet so does the generation of waste and particularly that of food waste. In order to tackle the world sustainability crisis, efforts to recover products from waste are critical. Here, we anaerobically recovered volatile fatty acids (VFAs) from food waste and analysed the microbial populations underpinning the process. An increased contribution of fungi relative to bacteria was observed throughout the reactor operation, with both kingdoms implicated into the main three steps of anaerobic digestion occurring within our systems: hydrolysis, acidogenesis and acetogenesis. Overall, Ascomycota, Proteobacteria and Firmicutes were found to drive the anaerobic digestion of food waste, with butyrate as the most abundant VFA likely produced by Clostridium using lactate as a precursor. Taken together we demonstrate that the generation of products of added-value from food waste results from cross-kingdoms microbial activities implicating fungi and bacteria.Publisher PDFPeer reviewe