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Towards Relativistic Skyrmions
Get PDFWe revisit baryons in the Skyrme model. Starting from static baryons in the helicity eigenstates, we generalize their wavefunctions to the non-static and relativistic regime. A new representation for gamma matrices in the soliton collective space is constructed and the corresponding Dirac equation is obtained. As an example, we draw consideration on how to apply this new representation on the calculus of vector current vacuum expectation values for baryon states of spin and isospin half and arbitrary momenta and we show how elastic form factors can be derived
Penetration of crustal melt beyond the Kunlun Fault into northern Tibet
Get PDFThe weak lithosphere of the Tibetan plateau is surrounded by rigid crustal blocks1 and the transition between these regimes plays a key role in the ongoing collision between India and Eurasia. Geophysical data2,3,4,5 and magmatic evidence6,7 support the notion that partial melt exists within the anomalously hot7,8 crust of northern Tibet. The Kunlun Fault, which accommodates the plateau’s eastward extrusion, has been identified as a significant rheological boundary4 between weak, warm Tibetan crust8 and the rigid eastern Kunlun–Qaidam block. Here we present reanalyses and remodelling of existing magnetotelluric data4, using an anisotropy code9 to obtain revised resistivity models. We find unequivocal evidence for anisotropy in conductivity at the northern edge of the Tibetan plateau. We interpret this anisotropy as the signature of intrusion of melt that penetrates north from the Tibetan plateau and weakens the crust beneath the Kunlun Shan. We suggest that our identification of a melt intrusion at the northern edge of the Tibetan plateau compromises the previous identification of the Kunlun Fault as an important rheological boundary. We conclude that the crustal melt penetration probably characterizes the growth of the plateau10 to the north, as well as accommodating the north–south crustal shortening in Tibet
Dinnseanchas Inbhear Chíochmhaine, "trí comaccomail na Góedelge", agus caibidil i stair litriú na Gaeilge
Get PDFBack-reaction of non-supersymmetric probes: phase transition and stability
Get PDFWe consider back-reaction by non-supersymmetric D7/anti-D7 probe branes in the Kuperstein-Sonnenschein model at finite temperature. Using the smearing technique, we obtain an analytical solution for the back-reacted background to leading order in N_f/N_c. This back-reaction explicitly breaks the conformal invariance and introduces a dimension 6 operator in the dual field theory which is an irrelevant deformation of the original conformal field theory. We further probe this back-reacted background by introducing an additional set of probe brane/anti-brane. This additional probe sector undergoes a chiral phase transition at finite temperature, which is absent when the back-reaction vanishes. We investigate the corresponding phase diagram and the thermodynamics associated with this phase transition. We also argue that additional probes do not suffer from any instability caused by the back-reaction, which suggests that this system is stable beyond the probe limit
Solitons and Yukawa couplings in nearly Kähler flux compactifications
Get PDFWe study vacuum states and symmetric fermions in equivariant dimensional reduction of Yang– Mills–Dirac theory over the six-dimensional homogeneous space SU(3)/U(1) × U(1) endowed with a family of SU(3)-structures including a nearly Kähler structure. We derive the fixed tree-level scalar potentials of the induced Yang–Mills–Higgs theory, and compute the dynamically generated gauge and Higgs boson masses as functions of the metric moduli of the coset space. We find an integrable subsector of the Higgs field theory which is governed by a sine-Gordon type model whose topological soliton solutions are determined nonperturbatively by the gauge coupling and which tunnel between families of infinitely degenerate vacua. The reduction of the Dirac action for symmetric fermions yields exactly massless chiral fermions, containing subsectors which have fixed tree-level Yukawa interactions. We compute dynamical fermion mass matrices explicitly and compare them at differents points of the moduli space, some of which support consistent heterotic flux vacua
Production of negative parity baryons in the holographic Sakai-Sugimoto model
Get PDFWe extend our investigation of resonance production in the Sakai-Sugimoto model to the case of negative parity baryon resonances. Using holographic techniques we extract the generalized Dirac and Pauli baryon form factors as well as the helicity amplitudes for these baryonic states. Identifying the first negative parity resonance with the experimentally observed S_11(1535), we find reasonable agreement with experimental data from the JLab-CLAS collaboration. We also estimate the contribution of negative parity baryons to the proton structure functions
Two Nugent manuscripts: the Nugent Duanaire and Queen Elizabeth's Primer
Get PDFThe political significance of two Irish manuscripts (National Library of Ireland MS G 992 (the Nugent Duanaire), and Elizabeth's Primer (Farmleigh)) in the context of moves to use the vernacular as a vehicle for the advance of the Reformation in Irelan
