56 research outputs found
Studying the Perturbed Wess-Zumino-Novikov-Witten SU(2)k Theory Using the Truncated Conformal Spectrum Approach
We study the Wess-Zumino-Novikov-Witten (WZNW) theory perturbed by
the trace of the primary field in the adjoint representation, a theory
governing the low-energy behaviour of a class of strongly correlated electronic
systems. While the model is non-integrable, its dynamics can be investigated
using the numerical technique of the truncated conformal spectrum approach
combined with numerical and analytical renormalization groups (TCSA+RG). The
numerical results so obtained provide support for a semiclassical analysis
valid at . Namely, we find that the low energy behavior is sensitive to
the sign of the coupling constant, . Moreover for this
behavior depends on whether is even or odd. With even, we find
definitive evidence that the model at low energies is equivalent to the massive
sigma model. For odd, the numerical evidence is more equivocal, but
we find indications that the low energy effective theory is critical.Comment: 30 pages, 19 eps figures, LaTeX2e file. Version 2: manuscript
accepted for publication; small changes in text and in one of the figure
Sine-Gordon multisoliton form factors in finite volume
Multi-soliton form factors in sine-Gordon theory from the bootstrap are
compared to finite volume matrix elements computed using the truncated
conformal space approach. We find convincing agreement, and resolve most of the
issues raised in a previous work.Comment: 24 pages, LaTeX2e file, 8 eps figures. v2: notations improved, some
explanatory text and references adde
Particle Formation and Ordering in Strongly Correlated Fermionic Systems: Solving a Model of Quantum Chromodynamics
In this paper we study a (1+1)-dimensional version of the famous
Nambu-Jona-Lasinio model of Quantum Chromodynamics (QCD2) both at zero and
finite hadron density. We use non-perturbative techniques (non-Abelian
bosonization and Truncated Conformal Space Approach). At zero density we
describe a formation of fermion three-quark (nucleons and -baryons) and
boson (two-quark mesons, six-quark deuterons) bound states and also a formation
of a topologically nontrivial phase. At finite hadron density, the model has a
rich phase diagram which includes phases with density wave and superfluid
quasi-long-range (QLR) order and also a phase of a baryon Tomonaga-Luttinger
liquid (strange metal). The QLR order results as a condensation of scalar
mesons (the density wave) or six-quark bound states (deuterons).Comment: 31 pages, pdflatex file, 7 figures; typos corrected, the version from
Phys. Rev.
Research with marginalised communities: reflections onengaging Roma Women in Northern England
This paper critically explores research with marginalised communities.We provide an insight into our work with the Roma community, reflectingon innovation, opportunities and barriers, alongside the need for morework in this area. A particular focus here surrounds novel methodologiesfor exploring the health and wellbeing of such groups and ways of coproducing research. The paper also raises awareness around arts-basedsocial prescribing with marginalised communities and the need toupscale work in this regard. Through doing so, we hope to influencepractice, raise awareness around work with the Roma community andenable more creativity within the broader field
Teixobactin analogues reveal enduracididine to be non-essential for highly potent antibacterial activity and lipid II binding
Abstract. Teixobactin is a highly promising antibacterial depsipeptide consisting of four D-amino acids and a rare L-allo-enduracididine
amino acid. L-allo-enduracididine is reported to be important for the highly potent antibacterial activity of teixobactin. However, it is also a
key limiting factor in the development of potent teixobactin analogues due to several synthetic challenges such as it is not commercially
available, requires a multistep synthesis, long and repititive couplings (16-30 hours). Due to all these challenges, the total synthesis of
teixobactin is laborious and low yielding (3.3%). In this work, we have identified a unique design and developed a rapid synthesis (10 min
μwave assisted coupling per amino acid, 30 min cyclisation) of several highly potent analogues of teixobactin with yields of 10-24% by
replacing the L-allo-enduracididine with commercially available non-polar residues such as leucine and isoleucine. Most importantly, the
Leu10-teixobactin and Ile10-teixobactin analogues have shown highly potent antibacterial activity against a broader panel of MRSA and
Enterococcus faecalis (VRE). Time-kill kinetics data indicate that both these compounds are superior to vancomycin against MRSA (16
times more potent). Furthermore, these synthetic analogues displayed identical antibacterial activity to natural teixobactin (MIC 0.25 μg/ml)
against MRSA ATCC 33591 despite their simpler design and ease of synthesis. Detailed NMR analyses have provided us with further
insight into the 3D structures of these important analogues. We have confirmed lipid II binding and measured the binding affinities of
individual amino acid residues of Ala10-teixobactin towards geranyl pyrophosphate (a lipid II mimic) by NMR to understand the nature and
strength of binding interactions of the amino acid residues. An antagonization assay further confirms a lipid II mediated mode of action.
Contrary to current understanding, we have shown that a cationic amino acid at position 10 is not essential for target (lipid II) binding and
potent antibacterial activity of teixobactin. We thus provide strong evidence contrary to the many assumptions made about the mechanism of
action of this exciting new antibiotic. Introduction of a non-cationic residue at position 10 allows for tremendous diversification in terms of
the design and synthesis of highly potent teixobactin analogues and lays the foundations for the development of teixobactin analogues as
new drug-like molecules to target MRSA and Mycobacterium tuberculosis
Relative entanglement entropies in 1 + 1-dimensional conformal field theories
We study the relative entanglement entropies of one interval between excited states of a 1+1 dimensional conformal field theory (CFT). To compute the relative entropy S(\u3c11\u2016\u3c10) between two given reduced density matrices \u3c11 and \u3c10 of a quantum field theory, we employ the replica trick which relies on the path integral representation of Tr(\u3c11\u3c1n 1210) and define a set of R\'enyi relative entropies Sn(\u3c11\u2016\u3c10). We compute these quantities for integer values of the parameter n and derive via the replica limit, the relative entropy between excited states generated by primary fields of a free massless bosonic field. In particular, we provide the relative entanglement entropy of the state described by the primary operator i 02\u3d5, both with respect to the ground state and to the state generated by chiral vertex operators. These predictions are tested against exact numerical calculations in the XX spin-chain finding perfect agreement. \ua9 2017, The Author(s)
R\ue9nyi entropies of generic thermodynamic macrostates in integrable systems
We study the behaviour of R\ue9nyi entropies in a generic thermodynamic macrostate of an integrable model. In the standard quench action approach to quench dynamics, the R\ue9nyi entropies may be derived from the overlaps of the initial state with Bethe eigenstates. These overlaps fix the driving term in the thermodynamic Bethe ansatz (TBA) formalism. We show that this driving term can be also reconstructed starting from the macrostate's particle densities. We then compute explicitly the stationary R\ue9nyi entropies after the quench from the dimer and the tilted N\ue9el state in XXZ spin chains. For the former state we employ the overlap TBA approach, while for the latter we reconstruct the driving terms from the macrostate. We discuss in full detail the limits that can be analytically handled and we use numerical simulations to check our results against the large time limit of the entanglement entropies
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