3,728 research outputs found
Transverse momentum broadening of heavy quark and gluon energy loss in Sakai-Sugimoto model
In this paper, we calculate the transverse momentum diffusion coefficient
kappa_T of heavy quark and gluon penetration length in the deconfinement phase
of Sakai-Sugimoto model, which is known as a holographic dual of large N_c QCD.
We find that for the heavy quark moving through the thermal plasma with a
constant velocity v<1, the transverse momentum diffusion coefficient kappa_T is
proportional to lamda*gamma^{{1/3}}*T^4/T_d, and the gluon penetration length
delta x is proportional to E^{{2/5}}. These results are different from those
calculated in N=4 super-Yang-Mills theory, where kappa_T is proportional to
lambda*gamma^{{1/2}}*T^3 and delta x is proportional to E^{{1/3}},
respectively. In the high energy limit, the difference between the two pairs of
results should be evident, so we expect that the future LHC experiments can
tell us which model is more closely related to the realistic strongly coupled
QCD at finite temperature.Comment: 26 pages, 6 figures, contents and references adde
All Off-Shell R^2 Invariants in Five Dimensional N=2 Supergravity
We construct supersymmetric completions of various curvature squared terms in
five dimensional supergravity with eight supercharges. Adopting the dilaton
Weyl multiplet, we obtain the minimal off-shell supersymmetric Ricci scalar
squared as well as all vector multiplets coupled curvature squared invariants.
Since the minimal off-shell supersymmetric Riemann tensor squared and
Gauss-Bonnet combination in the dilaton Weyl multiplet have been obtained
before, both the minimal off-shell and the vector multiplets coupled curvature
squared invariants in the dilation Weyl multiplet are complete. We also
constructed an off-shell Ricci scalar squared invariant utilizing the standard
Weyl multiplet. The supersymmetric Ricci scalar squared in the standard Weyl
multiplet is coupled to n number of vector multiplets by construction, and it
deforms the very special geometry. We found that in the supersymmetric AdS_5
vacuum, the very special geometry defined on the moduli space is modified in a
simple way. Finally, we study the magnetic string and electric black hole
solutions in the presence of supersymmetric Ricci scalar squared.Comment: 28 pages, v3: Typos Corrected, Version appeared in JHE
Extension of Starobinsky Model in Old Minimal Supergravity
We provide a succinct way to construct the supersymmetric completion of
in components using superconformal formulation of old minimal
supergravity. As a consequence, we obtain the polynomial supergravity
extending the supersymmetric Starobinsky model to any higher power of . The
supersymmetric vacua in polynomial supergravity are studied. We also
present the extended Minimal Volkov-Akulov-Starobinsky Model.Comment: 18 pages, new section added on the dual model, typos fixed,
references added, version appeared in CQ
Planck constraints on inflation in auxiliary vector modified theories
We show that the universal -attractor models of inflation can be
realized by including an auxiliary vector field for the Starobinsky
model with the Lagrangian . If the same procedure is applied
to general modified theories in which the Ricci scalar is replaced
by with constant , we
obtain the Brans-Dicke theory with a scalar potential and the Brans-Dicke
parameter . We also place observational constraints
on inflationary models based on auxiliary vector modified theories from
the latest Planck measurements of the Cosmic Microwave Background (CMB)
anisotropies in both temperature and polarization. In the modified Starobinsky
model, we find that the parameter is constrained to be
(68\,\%\,confidence level) from the bounds of the scalar spectral index and the
tensor-to-scalar ratio.Comment: 10 pages, 3 figure
- …