Results 91 to 100 of about 1,109,861 (332)

Spin-foam model for gravity coupled to massless scalar field [PDF]

Classical and quantum gravity, 2018
A spin-foam model is derived from the canonical model of loop quantum gravity coupled to a massless scalar field. We generalized to the full theory the scheme first proposed in the context of loop quantum cosmology by Ashtekar et al (2009 Phys. Lett.
M. Kisielowski, J. Lewandowski
semanticscholar   +1 more source

Hidden Quantum Gravity in 3d Feynman diagrams

, 2006
In this work we show that 3d Feynman amplitudes of standard QFT in flat and homogeneous space can be naturally expressed as expectation values of a specific topological spin foam model.
Aristide Baratin, Baez J C, Baratin A, Barrett J W, Barrett J W Garcia-Islas J M Martins J F, Freidel L, Freidel L, Freidel L, Freidel L, Freidel L Livine E R, Freidel L Livine E R, Freidel L Louapre D, Freidel L Majid S, Freidel L Starodubtsev A, Laurent Freidel, Noui K, Oriti D, Perez A, Polyakov A M, Ponzano G, Regge T, Singer I M, Taylor Y U Woodward C T   +22 more
core   +1 more source

Electroactive Metal–Organic Frameworks for Electrocatalysis

Advanced Functional Materials, EarlyView.
Electrocatalysis is crucial in sustainable energy conversion as it enables efficient chemical transformations. The review discusses how metal–organic frameworks can revolutionize this field by offering tailorable structures and active site tunability, enabling efficient and selective electrocatalytic processes.
Irena Senkovska, Yutong Luo, Ruyan Zhao, Jianjun Zhang, Mingchao Wang, Xinliang Feng, Eike Brunner, Stefan Kaskel   +7 more
wiley   +1 more source

Non-geometric Kaluza-Klein monopoles and magnetic duals of M-theory R-flux backgrounds

Journal of High Energy Physics, 2017
We introduce a magnetic analogue of the seven-dimensional nonassociative octonionic R-flux algebra that describes the phase space of M2-branes in four-dimensional locally non-geometric M-theory backgrounds.
Dieter Lüst, Emanuel Malek, Richard J. Szabo   +2 more
doaj   +1 more source

Gravity as BF theory plus potential

, 2009
Spin foam models of quantum gravity are based on Plebanski's formulation of general relativity as a constrained BF theory. We give an alternative formulation of gravity as BF theory plus a certain potential term for the B-field.
Krasnov, Kirill
core   +1 more source

Tunable Coordination Number in Non‐Metal‐Introduced Copper Catalysts Enables High‐Performance Electrochemical CO2 Reduction to C2 Products

Advanced Functional Materials, EarlyView.
Copper catalysts introduced with different non‐metallic elements regulating the coordination number of Cu are prepared by magnetron sputtering. Reducing the Cu coordination number enhances C─C coupling and boosts C2+ product selectivity, by lowering the energy barrier for the *CO → *CHO conversion step. The optimized Si‐doped Cu catalyst achieves a C2+
Xiaoye Du, Bo Gao, Yixuan Yang, Young In Jo, Dan Qian, Chunhui Xiao, Shujiang Ding, Zhongxiao Song, Ki Tae Nam   +8 more
wiley   +1 more source

SPIN FOAM MODELS OF QUANTUM GRAVITY [PDF]

Mathematical, Theoretical and Phenomenological Challenges Beyond the Standard Model, 2005
We give a short review of the spin foam models of quantum gravity, with an emphasis on the Barret-Crane model. After explaining the shortcomings of the Barret-Crane model, we briefly discuss two new approaches, one based on the 3d spin foam state sum invariants for the embedded spin networks, and the other based on representing the string scattering ...
openaire   +2 more sources

Device Integration Technology for Practical Flexible Electronics Systems

Advanced Functional Materials, EarlyView.
Flexible device integration technologies are essential for realizing practical flexible electronic systems. In this review paper, wiring and bonding techniques critical for the industrial‐scale manufacturing of wearable devices are emphasized based on flexible electronics.
Masahito Takakuwa, Kento Yamagishi, Sunghoon Lee, Yusaku Tagawa, Takao Someya, Tomoyuki Yokota   +5 more
wiley   +1 more source

Decorated tensor network renormalization for lattice gauge theories and spin foam models

New Journal of Physics, 2016
Tensor network techniques have proved to be powerful tools that can be employed to explore the large scale dynamics of lattice systems. Nonetheless, the redundancy of degrees of freedom in lattice gauge theories (and related models) poses a challenge for
Bianca Dittrich, Sebastian Mizera, Sebastian Steinhaus   +2 more
doaj   +1 more source

Effective action and semiclassical limit of spin foam models

, 2011
We define an effective action for spin foam models of quantum gravity by adapting the background field method from quantum field theory. We show that the Regge action is the leading term in the semi-classical expansion of the spin foam effective action ...
A Miković, Abbot L, Baez J C, Barrett J W, Barrett J W, Barrett J W Dowdall R J Fairbairn W J Hellmann F Pereira R, Bianchi E, Fairbairn W Meusburger C, Freidel L, M Vojinović, Magliaro E, Makela J, Miković A, Miković A, Miković A, Miković A Vojinović M, Miković A Vojinović M   +16 more
core   +1 more source