16 research outputs found
Double non-perturbative gluon exchange: an update on the soft Pomeron contribution to pp scattering
We employ a set of recent, theoretically motivated, fits to non-perturbative
unquenched gluon propagators to check in how far double gluon exchange can be
used to describe the soft sector of pp scattering data (total and differential
cross section). In particular, we use the refined Gribov--Zwanziger gluon
propagator (as arising from dealing with the Gribov gauge fixing ambiguity) and
the massive Cornwall-type gluon propagator (as motivated from Dyson-Schwinger
equations) in conjunction with a perturbative quark-gluon vertex, next to a
model based on the non-perturbative quark-gluon Maris-Tandy vertex, popular
from Bethe-Salpeter descriptions of hadronic bound states. We compare the cross
sections arising from these models with "older" ISR and more recent TOTEM and
ATLAS data. The lower the value of total energy \sqrt{s}, the better the
results appear to be.Comment: 14 pages, 8 .pdf figures. To appear in Phys.Rev.
Effective field theories for interacting boundaries of 3D topological crystalline insulators through bosonisation
Here, we analyse two Dirac fermion species in two spatial dimensions in the presence of general quartic contact interactions. By employing functional bosonisation techniques, we demonstrate that depending on the couplings of the fermion interactions the system can be effectively described by a rich variety of topologically massive gauge theories. Among these effective theories, we obtain an extended Chern–Simons theory with higher order derivatives as well as two coupled Chern–Simons theories. Our formalism allows for a general description of interacting fermions emerging, for example, at the gapped boundary of three-dimensional topological crystalline insulators
Newton-Hooke/Carrollian expansions of (A)dS and Chern-Simons gravity
We construct finite- and infinite-dimensional non-relativistic extensions of the Newton-Hooke and Carroll (A)dS algebras using the algebra expansion method, starting from the (anti-)de Sitter relativistic algebra in D dimensions. These algebras are also shown to be embedded in different affine Kac-Moody algebras. In the three-dimensional case, we construct Chern-Simons actions invariant under these symmetries. This leads to a sequence of non-relativistic gravity theories, where the simplest examples correspond to extended Newton-Hooke and extended (post-)Newtonian gravity together with their Carrollian counterparts
Topological gravity and gauged Wess-Zumino-Witten term
AbstractIt is shown that the actions for topological gravity in even dimensions found by A. Chamseddine in Ref. [1] is, except a multiplicative constant, a gauged Wess–Zumino–Witten term
Symmetries of Post-Galilean Expansions
In this note we introduce an infinite-dimensional space on which an infinite-dimensional generalization of the Galilei group acts. Standard Minkowski space can be modelled in this space and its symmetries yield an embedding of the Poincar\'e group in the infinite extension. The extension has an interpretation in terms of post-Newtonian corrections to Galilei symmetries. We also construct particle and string actions that are invariant under these transformations
Double nonperturbative gluon exchange: An update on the soft-Pomeron contribution to pp scattering
© 2017 American Physical Society. We employ a set of recent, theoretically motivated fits to nonperturbative unquenched gluon propagators to check on how far double gluon exchange can be used to describe the soft sector of pp scattering data (total and differential cross section). In particular, we use the refined Gribov-Zwanziger gluon propagator (as arising from dealing with the Gribov gauge fixing ambiguity) and the massive Cornwall-type gluon propagator (as motivated from Dyson-Schwinger equations) in conjunction with a perturbative quark-gluon vertex, next to a model based on the nonperturbative quark-gluon Maris-Tandy vertex, popular from Bethe-Salpeter descriptions of hadronic bound states. We compare the cross sections arising from these models with older ISR and more recent TOTEM and ATLAS data. The lower the value of total energy s, the better the results appear to be.14 pages, 8 .pdf figures. To appear in Phys.Rev.Cstatus: publishe
Geometric actions for three-dimensional gravity
The solution space of three-dimensional asymptotically anti-de Sitter or flat
Einstein gravity is given by the coadjoint representation of two copies of the
Virasoro group in the former and the centrally extended BMS group in the
latter case. Dynamical actions that control these solution spaces are usually
constructed by starting from the Chern-Simons formulation and imposing all
boundary conditions. In this note, an alternative route is followed. We study
in detail how to derive these actions from a group-theoretical viewpoint by
constructing geometric actions for each of the coadjoint orbits, including the
appropriate Hamiltonians. We briefly sketch relevant generalizations and
potential applications beyond three-dimensional gravity.Comment: 29 page