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pro vyhledávání: '"A. B. Whittingham"'
Scattering and ionizing cross sections and rates are calculated for ultracold collisions between metastable helium atoms using a fully quantum-mechanical close-coupled formalism. Homonuclear collisions of the bosonic ${}^{4}$He$^{*} +{}^{4}$He$^{*}$
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::db1f573e3d6fb0cf3c9b31f0c811f1e1
http://arxiv.org/abs/1904.01281
http://arxiv.org/abs/1904.01281
Autor:
Michael J. Brown, Ian B. Whittingham
Publikováno v:
Nuclear Physics B, Vol 900, Iss C, Pp 477-500 (2015)
Nuclear Physics B
Nuclear Physics B
Approximations based on two-particle irreducible (2PI) effective actions (also known as $\Phi$-derivable, Cornwall-Jackiw-Tomboulis or Luttinger-Ward functionals depending on context) have been widely used in condensed matter and non-equilibrium quan
Publikováno v:
Composites Part A: Applied Science and Manufacturing. 40:1419-1432
The hard-patch approach to scarf repairs involves adhesively bonding a pre-formed patch into the scarf cavity. This approach has several potential advantages compared with the conventional soft-patch approach, which involves forming the patch from pr
Autor:
G. Peach, Ian B. Whittingham
Publikováno v:
New Astronomy Reviews. 53:227-230
Accurate pressure broadened profiles of alkali resonance doublets are needed for modelling of the atmospheres of cool stars and for generating their synthetic spectra in the region 400–900 nm. When the usual impact theory of line broadening is used
Autor:
Ian B. Whittingham, Michael J. Brown
Two particle irreducible effective actions (2PIEAs) are valuable non-perturbative techniques in quantum field theory; however, finite truncations of them violate the Ward identities (WIs) of theories with spontaneously broken symmetries. The symmetry
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::4d5f20a803b3c8ebc547642597c49f44
We investigate the linear response of an O(N) scalar quantum field theory subject to external perturbations using the symmetry improved two particle irreducible effective action formalism [A. Pilaftsis and D. Teresi, Nucl. Phys. B874, 594 (2013)]. De
Externí odkaz:
https://explore.openaire.eu/search/publication?articleId=doi_dedup___::1b9f061ddba6e6129cb96caddcd34986
Autor:
Michael J. Brown, Ian B. Whittingham
Publikováno v:
Physical Review D. 91
N-particle irreducible effective actions (nPIEA) are a powerful tool for extracting nonperturbative and nonequilibrium physics from quantum field theories. Unfortunately, practical truncations of nPIEA can unphysically violate symmetries. Pilaftsis a
Publikováno v:
Journal of Physics B: Atomic, Molecular and Optical Physics. 37:4561-4570
Collisions between tightly confined atoms can lead to ionization and hence to loss of atoms from the trap. We develop second-order perturbation theory for a tensorial perturbation of a spherically symmetric system and the theory is then applied to pr
Publikováno v:
Journal of Physics: Conference Series. 810:012003
Photoassociation processes are studied in ultracold collisions between different isotopes of metastable He(2^3S) and He(2^3P) atoms; Penning and associative ionization rates for collisions between two He(2^3S) atoms are also obtained. Comparisons are
Autor:
I, Siddiqui, B, Whittingham, K, Meadowcroft, M, Richardson, J C, Cooper, J, Belcher, E, Morris, K M K, Ismail
Publikováno v:
BMJ Open
Objective Safe midwifery staffing levels on delivery suites is a priority area for any maternity service. Escalation policies are tools that provide an operational response to emergency pressures. The aim of this study was to assess the feasibility o