45,318 research outputs found
Quasi-homologous spherically symmetric branes and their symmetry breaking
We revisit the dynamical system based approach of spherically symmetric
vacuum braneworlds, pointing out and studying the existence of a transcritical
bifurcation as the dark pressure parameter changes its sign, we analyze some
consequences of not discard the brane cosmological constant. For instance, it
is noteworthy that the existence of an isothermal state equation between the
dark fluid parameters cannot be obtained via the requirement of a
quasi-homologous symmetry of the vacuum.Comment: 20 pages, 12 figures. To appear in EPJ
Modified Kerr-Schild Method applied to Gravity f(R)
We propose an adaptation of the Kerr-Schild method by implementing the
correspondence relations (mapping) between Ricci-based Gravity (RBG) and
General Relativity (GR). Basically, we generate GR known solutions from a
canonical metric with a well-defined form and then obtain the configuration of
this solution for the Gravity f(R). The new method allows us to perturb the
metric associated with GR with a null geodetic vector, but instead of taking us
to a new solution described by Einstein's gravitational sector, it allows us to
configure this solution in an RBG
On the particle spectrum and the conformal window
We study the SU(3) gauge theory with twelve flavours of fermions in the
fundamental representation as a prototype of non-Abelian gauge theories inside
the conformal window. Guided by the pattern of underlying symmetries, chiral
and conformal, we analyze the two-point functions theoretically and on the
lattice, and determine the finite size scaling and the infinite volume fermion
mass dependence of the would-be hadron masses. We show that the spectrum in the
Coulomb phase of the system can be described in the context of a universal
scaling analysis and we provide the nonperturbative determination of the
fermion mass anomalous dimension gamma*=0.235(46) at the infrared fixed point.
We comment on the agreement with the four-loop perturbative prediction for this
quantity and we provide a unified description of all existing lattice results
for the spectrum of this system, them being in the Coulomb phase or the
asymptotically free phase. Our results corroborate the view that the fixed
point we are studying is not associated to a physical singularity along the
bare coupling line and estimates of physical observables can be attempted on
either side of the fixed point. Finally, we observe the restoration of the U(1)
axial symmetry in the two-point functions.Comment: 40 pages, 22 figure
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