31,401 research outputs found
Local Magnetization in Critical Ising Model with Boundary Magnetic Field
We discribe a simple way to derive spin correlation functions in 2D Ising
model at critical temperature but with nonzero magnetic field at the boundary.
Local magnetization (i.e. one-point function) is computed explicitly for
half-plane and disk geometries.Comment: 8 pages, RU-93-5
Accelerating Universe from Extra Spatial Dimension
We present a simple higher dimensional FRW type of model where the
acceleration is apparently caused by the presence of the extra dimensions.
Assuming an ansatz in the form of the deceleration parameter we get a class of
solutions some of which shows the desirable feature of dimensional reduction as
well as reasonably good physical properties of matter. Interestingly we do not
have to invoke an extraneous scalar field or a cosmological constant to account
for this acceleration. One argues that the terms containing the higher
dimensional metric coefficients produces an extra negative pressure that
apparently drives the inflation of the 4D space with an accelerating phase. It
is further found that in line with the physical requirements our model admits
of a decelerating phase in the early era along with an accelerating phase at
present.Further the models asymptotically mimic a steady state type of universe
although it starts from a big type of singularity. Correspondence to Wesson's
induced matter theory is also briefly discussed and in line with it it is
argued that the terms containing the higher dimensional metric coefficients
apparently creates a negative pressure which drives the inflation of the
3-space with an accelerating phase.Comment: 0
Spherical collapse of a heat conducting fluid in higher dimensions without horizon
We consider a scenario where the interior spacetime,described by a heat
conducting fluid sphere is matched to a Vaidya metric in higher
dimensions.Interestingly we get a class of solutions, where following heat
radiation the boundary surface collapses without the appearance of an event
horizon at any stage and this happens with reasonable properties of matter
field.The non-occurrence of a horizon is due to the fact that the rate of mass
loss exactly counterbalanced by the fall of boundary radius.Evidently this
poses a counter example to the so-called cosmic censorship hypothesis.Two
explicit examples of this class of solutions are also given and it is observed
that the rate of collapse is delayed with the introduction of extra
dimensions.The work extends to higher dimensions our previous investigation in
4D.Comment: 6 page
Including the Fermion Vacuum Fluctuations in the flavor Polyakov Quark Meson Model
We consider the flavor Polyakov Quark Meson Model and study the
effect of including fermion vacuum fluctuations on the thermodynamics and phase
diagram. The resulting model predictions are compared to the recent QCD lattice
simulations by the HotQCD and Wuppertal-Budapest collaborations. The variation
of the thermodynamic quantities across the phase transition region becomes
smoother. This results in better agreement with the lattice data. Depending on
the value of the mass of the sigma meson, including the vacuum term results in
either pushing the critical end point into higher values of the chemical
potential or excluding the possibility of a critical end point altogether.Comment: 15 figures, some parts rewritten, new figures adde
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