17 research outputs found
Anomalous Strangeness Transport
Nondissipative transport of strangeness is studied in a chiral hadronic
plasma with three flavors. In the phase in which chiral symmetry is preserved,
strangeness transport is found to be driven by both an external magnetic field
and fluid vorticity. As for the constitutive relations of the baryon and
electromagnetic currents, they exhibit vortical terms proportional to the
strangeness chemical potential. In the superfluid phase, transverse
nondissipative diffusion of the baryon, electromagnetic, and strangeness
charges is found, which survives in the limit of vanishing chiral imbalance and
mixes in a fashion similar to standard dissipative diffusion in quark-gluon
plasma.Comment: 11 pages, LaTeX, no figure
Projectivity of Planar Zeros in Field and String Theory Amplitudes
We study the projective properties of planar zeros of tree-level scattering
amplitudes in various theories. Whereas for pure scalar field theories we find
that the planar zeros of the five-point amplitude do not enjoy projective
invariance, coupling scalars to gauge fields gives rise to tree-level
amplitudes whose planar zeros are determined by homogeneous polynomials in the
stereographic coordinates labelling the direction of flight of the outgoing
particles. In the case of pure gauge theories, this projective structure is
generically destroyed if string corrections are taken into account. Scattering
amplitudes of two scalars with graviton emission vanish exactly in the planar
limit, whereas planar graviton amplitudes are zero for helicity violating
configurations. These results are corrected by string effects, computed using
the single-valued projection, which render the planar amplitude nonzero.
Finally, we discuss how the structure of planar zeros can be derived from the
soft limit behavior of the scattering amplitudes.Comment: 39 page, 5 figures. v2: typos corrected. It matches the version
published in Journal of High Energy Physic
Einstein y la Geometria
This is a semipopular introduction to the Special and General Theory of
Relativity, with special emphasis on the geometrical aspects of both theories
and their physical implications.Comment: In Spanish, 20 pages. LaTeX, 8 figures. To appear in the Einstein
Special Issue of "Revista Espanola de Fisica
The Double Copy Structure of Soft Gravitons
The subleading corrections to factorization theorems for soft bremsstrahlung
in nonabelian gauge theories and gravity are investigated in the case of a five
point amplitude with four scalars. Building on recent results, we write the
action of the angular momentum operators on scattering amplitudes as
derivatives with respect to the Mandelstam invariants to uncover a double copy
structure in the contribution of the soft graviton to the amplitude, both in
the leading term and the first correction. Using our approach, we study
Gribov's theorem as extended to nonabelian gauge theories and gravity by
Lipatov, and find that subleading corrections can be obtained from those to
Low's theorem by dropping the terms with derivatives with respect to the
center-of-mass energy, which are suppressed at high energies. In this case, the
emitted gravitons are not necessarily soft.Comment: 20 pages. LaTeX, 1 figure. v2: minor changes, references added.
Matches the version published in Journal of High Energy Physic
Color-kinematics duality and dimensional reduction for graviton emission in Regge limit
In this talk we review the work in [1,2,3] where we have studied the
applicability of the color-kinematics duality to the scattering of two
distinguishable scalar matter particles with one gluon emission in QCD, or one
graviton emission in Einstein gravity. We have shown that the duality works
well in the Regge limit under two different extensions of the gauge theory: the
introduction of a new scalar contact interaction and the relaxation of the
distinguishability of the scalars. Both modifications correspond to theories
obtained by dimensional reduction from higher-dimensional pure gauge theories.Comment: 10 pages, no figures. Presented by Agustin Sabio Vera at the Low x
workshop, May 30 - June 4 2013, Rehovot and Eilat, Israe
Color-Kinematics Duality in Multi-Regge Kinematics and Dimensional Reduction
In this note we study the applicability of the color-kinematics duality to
the scattering of two distinguishable scalar matter particles with gluon
emission in QCD, or graviton emission in Einstein gravity. Previous analysis
suggested that direct use of the Bern-Carrasco-Johansson double-copy
prescription to matter amplitudes does not reproduce the gravitational
amplitude in multi-Regge kinematics. This situation, however, can be avoided by
extensions to the gauge theory, while maintaning the same Regge limit. Here we
present two examples of these extensions: the introduction of a scalar contact
interaction and the relaxation of the distinguishability of the scalars. In
both cases new diagrams allow for a full reconstruction of the correct Regge
limit on the gravitational side. Both modifications correspond to theories
obtained by dimensional reduction from higher-dimensional gauge theories.Comment: 16 pages, 1 figure; v2 minor changes, typos corrected. It matches the
version published in JHE
Critical formation of trapped surfaces in the collision of gravitational shock waves
We study the formation of marginally trapped surfaces in the head-on
collision of two shock waves both in anti-de Sitter and Minkowski space-time in
various dimensions as a function of the spread of the energy density in
transverse space. For D=4 and D=5 it is shown that there exists a critical
value of this spread above which no solution to the trapped surface equation is
found. In four dimensions the trapped surface at criticality has a finite size,
whereas in five the critical size vanishes. In both cases we find scaling
relations characterized by critical exponents. Finally, when D>5 there is
always a solution to the trapped surface equation for any transverse spread.Comment: 16 page