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In classical physics, calculating the slack of a hanging chain is a problem that has attracted interest. This study aims to solve this problem through experiment and theory. When the length and distance of both the ends of a hanging chain are given, the length of slack can be expressed by a Lambert W function or an irrational function within a certain distance. Herein, a simple observation of the slack is presented. The result obtained is one of the applications of the Lambert W function in the field of physics. Though the shape of a hanging chain is well-known to be a catenary, the calculation of slack possesses richer aspects of mathematical physics., Comment: 11 pages, 6 figures, v2: comments added, misprints corrected, v3: corrected some typos

We present a simple model where anisotropic evolution is driven by kinetic term in extra dimensions. By introducing a canonical or a ghost kinetic term, the possibility of anisotropy is studied., Comment: 8 pages, added references

This paper has been withdrawn by the author., Comment: This paper has been withdrawn. The conclusions are modified due to crucial errors in equation 24, 25

The solution to the Euler-Lagrange equation is an extremal functional.To understand that the functional is stationary at local extrema (maxima or minima), we propose a physics experiment that involves using soap film to form a catenoid. A catenoid is a surface that is formed between two coaxial circular rings and is classified mathematically as a minimal surface.Using soap film, we create catenoids between two rings and characterize the catenoid in-situ while varying distance between rings. The shape of the soap film is very interesting and can be explained using dynamic mechanics. By observing catenoid, physics students can observe local extrema phenomena. We stress that in-situ observation of soap film catenoids is an appropriate physics experiment that combines theory and experimentation., Comment: 13 pages, 9 figures; title is modified, final version to appear in European Journal of Physics

We drive the cosmological solutions of five-dimensional model with $1/H^{2}$ term $(H^{2}\equiv H_{MNPQ}H^{MNPQ})$, where $H_{MNPQ}$ is 4-form field strength. The behaviors of the scale factors and the scalar potential in effective theory are examined.As a consequence, we show that the universe changes from decelerated expansion to accelerated expansion in Einstein frame of the four-dimensional theory., Comment: 10 pages, 2 figures, version to appear in JCAP

We find that holographic dark energy model with non-minimally coupled scalar field gives rise to an accelerating universe by choosing Hubble scale as IR cutoff. We show viable range of a non-minimal coupling parameter in the framework of this model., Comment: 7 pages, no figure, corrected some typos, to be published in Europhys. Lett

We derive the scalar potential in zero mode effective action arising from a de Sitter brane embedded in five dimensions with bulk cosmological constant $\Lambda$. The scalar potential for a scalar field canonically normalized is given by the sum of exponential potentials. In the case of $\Lambda=0$ and $\Lambda>0$, we point out that the scalar potential has an unstable local maximum at the origin and exponentially vanishes for large positive scalar field. In the case of $\Lambda<0$, the scalar potential has an unstable local maximum at the origin and a stable local minimum, it is shown that the positive cosmological constant in brane is reduced by negative potential energy of scalar at minimum., Comment: 14 pages, 5 figures, add the section of cosmological implications

Motivated by recent accelerating cosmological model, we derive the solutions to vacuum Einstein equation in $(d+1)$-dimensional Minkowski space with $n$-dimensional hyperbolic manifold. The conditions of accelerating expansion are given in such a set up., Comment: 7 pages, no figure, corrected some typos, to appear in JCAP

We calculate the Casimir energies due to matter fields with various boundary conditions along two compact directions in $T^{2}$ compactification. We discuss whether the Casimir energies generate attractive or repulsive forces. On the theories with extra dimensions, the Casimir energy plays a crucial role in the mechanism for stabilizing the size of extra dimensions. Finally we argue a procedure of the application to $Z_{2}$ orbifold., Comment: 17 pages, no figure, title modified, to appear in Nucl.Phys.B

We calculate small correction terms to gravitational potential on Randall-Sundrum brane with an induced Einstein term. The behaviors of the correction terms depend on the magnitudes of $AdS$ radius $k^{-1}$ and a characteristic length scale $\l$ of model. We represent the gravitational potential for arbitrary $k$ and $\l$ at all distances., Comment: 7 pages, no figure. To appear in Phys. Lett. B

In the $SU(6) \times SU(2)_R$ string-inspired model, we evolve the couplings and the masses down from the string scale $M_S$ using the renormalization group equations and minimize the effective potential. This model has the flavor symmetry including the binary dihedral group $\tilde{D}_4$. We show that the scalar mass squared of the gauge non-singlet matter field possibly goes negative slightly below the string scale. As a consequence, the precocious radiative breaking of the gauge symmetry down to the standard model gauge group can occur. In the present model, the large Yukawa coupling which plays an important role in the symmetry breaking is identical with the colored Higgs coupling related to the longevity of the proton., Comment: 15 pages, 2 figures

We study the value of cosmological constant in de Sitter brane embedded in five dimensions with positive, vanishing and negative bulk cosmological constant. In the case of negative bulk cosmological constant, we show that not zero but tiny four-dimensional cosmological constant can be realized by tiny deviation from bulk curvature of the Randall-Sundrum model., Comment: 9 pages, 1 figure, latex