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Massive photon and dark energy
Kouwn, Seyen,Oh, Phillial,Park, Chan-Gyung American Physical Society 2016 Physical Review D Vol.93 No.8
<P>We investigate the cosmology of massive electrodynamics and explore the possibility whether the massive photon could provide an explanation of dark energy. The action is given by the scalar-vector-tensor theory of gravity, which is obtained by nonminimal coupling of the massive Stueckelberg QED with gravity; its cosmological consequences are studied by paying particular attention to the role of photon mass. We find that the theory allows for cosmological evolution where the radiation- and matter-dominated epochs are followed by a long period of virtually constant dark energy that closely mimics a Alpha CDM model. We also find that the main source of the current acceleration is provided by the nonvanishing photon mass governed by the relation Alpha similar to m(2). A detailed numerical analysis shows that the nonvanishing photon mass on the order of similar to 10-34 eV is consistent with current observations. This magnitude is far less than the most stringent limit on the photon mass available so far, which is on the order of m <= 10(-27) eV.</P>
ELKO SPINOR MODEL WITH TORSION AND COSMOLOGY
KOUWN, SEYEN,LEE, JOOHAN,LEE, TAE HOON,OH, PHILLIAL World Scientific 2013 Modern physics letters A Vol.28 No.29
<P> We investigate the cosmology of ELKO spinor model when minimal coupling with torsion is included. Unlike the Dirac spinor which interacts only with the totally anti-symmetric components of torsion tensor, we find the interaction of the time component of the trace of torsion tensor with ELKO spinor provides different aspects of cosmology with fermions. We discuss a couple of cases with given potentials of ELKO spinor which can result in interesting cosmological consequences. Especially, we show that there exists an exact cosmological solution in which the universe began its acceleration only recently and this solution is an attractor. This corresponds to specific forms of torsion and potential with a mild fine-tuning which can address the coincidence problem. </P>
Dark Energy with Logarithmic Cosmological Fluid
Seyen Kouwn,오필열 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.65 No.6
We propose a dark energy model with a logarithmic cosmological fluid which can result in a verysmall current value of the dark energy density and avoid the coincidence problem without muchfine-tuning. We construct a couple of dynamical models that could realize this dark energy at verylow energy in terms of the quintessence of four scalar fields and discuss the current acceleration ofthe Universe. Numerical values can be made to be consistent with the accelerating Universe byadjusting the two parameters of the theory. The potential can be given only in terms of the scalefactor, but the explicit form at very low energy can be obtained in terms of the scalar field to yieldof the form [수식]. Some discussions and the physical implications of thisapproach are given.
Hamiltonian formalism of topologically massive electrodynamics
Kim, Taegyu,Kouwn, Seyen,Oh, Phillial World Scientific Publishing Company 2019 Modern Physics Letters A Vol.34 No.10
<P>We consider the four-dimensional topologically massive electrodynamics in which a gauge field interacts with rank two antisymmetric tensor field through a topological interaction. The photon becomes massive by eating the rank two tensor field, which is dual to the Higgs mechanism. We explicitly demonstrate the nature of the mechanism by performing a canonical analysis of the theory and discuss various aspects of it.</P>
Classically scale invariant inflation, supermassive WIMPs, and adimensional gravity
Farzinnia, Arsham,Kouwn, Seyen American Physical Society 2016 Physical review. D Vol.93 No.6
<P>We introduce a minimal and yet comprehensive framework with CP and classical scale symmetries in order to simultaneously address the hierarchy problem, neutrino masses, dark matter, and inflation. One complex gauge singlet scalar and three flavors of the right-handed Majorana neutrinos are added to the standard model content, facilitating the see-saw mechanism, among others. An adimensional theory of gravity (Agravity) is employed, allowing for the trans-Planckian field excursions. The weak and Planck scales are induced by the Higgs portal and the scalar nonminimal couplings, respectively, once a Coleman-Weinberg dynamically generated vacuum expectation value for the singlet scalar is obtained. All scales are free from any mutual quadratic destabilization. The CP symmetry prevents a decay of the pseudoscalar singlet, rendering it a suitable WIMPzilla dark matter candidate with the correct observational relic abundance. Identifying the pseudo-Nambu-Goldstone boson of the (approximate) scale symmetry with the inflaton field, the model accommodates successful slow-roll inflation, compatible with the observational data. We reach the conclusion that a pseudo-Nambu-Goldstone inflaton, within a classically scale-symmetric framework, yields lighter WIMPzillas.</P>
Exact BPS Kink in BCFT, DBI EFT, NCFT, and BSFT
김찬주,김윤배,권오갑,Seyen Kouwn 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.50 No.I
We discuss single topological BPS kinks with non-zero thickness, which are exact solutions in var- ious contexts including Dirac-Born-Infeld type effective field theory, noncommutative field theory, boundary conformal field theory, and boundary string field theory. The tachyon field is monoton- ically increasing (or decreasing) and connects the isolated vacua at positive and negative infinity irrespective of the theories of our interest. It is expressed by a simple linear function, (X) / X, in the case of boundary conformal field theory. The obtained tachyon kink in the presence of critical electromagnetic field is interpreted as a single thick BPS D(p.1)-brane (or D(p.1)F1-composite) inside an unstable Dp-brane with background fluid of fundamental strings.
Homogeneous rolling tachyons in boundary string field theory
Ishida, Akira,Kim, Yoonbai,Kouwn, Seyen Elsevier 2006 Physics letters: B Vol.638 No.2
<P><B>Abstract</B></P><P>We study decay of a flat unstable D<I>p</I>-brane in the context of boundary string field theory action. Three types of homogeneous rolling tachyons are obtained without and with Born–Infeld type electromagnetic field.</P>