Minimal dark matter in type III seesaw (2009)
We explore the possibility of a new dark matter candidate in the supersymmetric type III seesaw mechanism where a neutral scalar component of the Y=0 triplet can be the lightest supersymmetric...
Dark matter and sub-GeV hidden U(1) in GMSB models (2008)
Chun, Eung Jin, Park, Jong-Chul
Motivated by the recent PAMELA and ATIC data, one is led to a scenario with heavy vector-like dark matter in association with a hidden $U(1)_X$ sector below GeV scale. Realizing this idea in the...
Chun, Eung Jin, Evans, Jason L, Morrissey, David E, Wells, James D
Motivated by the observation of neutrino oscillations, we extend the Higgs boson exempt no-scale supersymmetry model (HENS) by adding three heavy right-handed neutrino chiral supermultiplets to...
Chun, Eung Jin, Evans, Jason L., Morrissey, David E., Wells, James D.
Motivated by the observation of neutrino oscillations, we extend the Higgs boson exempt no-scale supersymmetry model (HENS) by adding three heavy right-handed neutrino chiral supermultiplets to...
Dirac Leptogenesis in extended nMSSM (2008)
We show that a version of the nearly Minimal Supersymmetric Standard Model (nMSSM), extended only in the singlet sector to include the additional superfields of right-handed neutrinos and very heavy...
Flaxino dark matter and stau decay (2008)
Chun, Eung Jin, Kim, Hang Bae, Kohri, Kazunori, Lyth, David H.
If the spontaneous breaking of Peccei-Quinn symmetry comes from soft supersymmetry breaking, the fermionic partners of the symmetry-breaking fields have mass of order the gravitino mass, and are...
Quintessential kination and leptogenesis (2007)
Chun, Eung Jin, Scopel, Stefano
Thermal leptogenesis induced by the CP-violating decay of a right-handed neutrino (RHN) is discussed against the background of quintessential kination, i.e., in a cosmological model where the energy...
Quintessential Kination and Leptogenesis (2007)
Chun, Eung Jin, Scopel, Stefano
Thermal leptogenesis induced by the CP-violating decay of a right-handed neutrino (RHN) is discussed in the background of quintessential kination, i.e., in a cosmological model where the energy...
Axino Light Dark Matter and Neutrino Masses with R-parity Violation (2006)
Motivated by the recent observation of the 511 keV $\gamma$-ray line emissions from the galactic bulge and an explanation for it by the decays of light dark matter particles, we consider the light...
Cosmological Aspects of the D-brane World (2006)
Cho, Inyong, Chun, Eung Jin, Kim, Hang Bae, Kim, Yoonbai
The D-brane world is an idea that we are living on the D-brane imbedded in a 10- or 11-dimensional spacetime of string theories, aiming at the construction of realistic models from string theories....
String Cosmology of the D-brane Universe (2006)
Cho, Inyong, Chun, Eung Jin, Kim, Hang Bae, Kim, Yoonbai
We analyze homogeneous anisotropic cosmology driven by the dilaton and the self-interacting ``massive'' antisymmetric tensor field which are indispensable bosonic degrees with the graviton in the...
Cosmological implication of antisymmetric tensor field on D-brane (2006)
Cho, Inyong, Chun, Eung Jin, Kim, Hang Bae, Kim, Yoonbai
We discuss the cosmological implications of an antisymmetric tensor field when it experiences a kind of ``Higgs mechanism,'' including nonlocal interaction terms, on D-branes. Even when a huge...
Testing Neutrino Mass Models (2005)
The existence of the neutrino masses and mixing would be an important window into the nature of physics beyond the Standard Model, which will be searched for in the forthcoming experiments such as...
TeV leptogenesis in Z-prime models and its collider probe (2005)
We show that the U(1)-prime models linked with the seesaw mechanism at TeV scale can lead to a successful baryogenesis through soft leptogenesis with a resonant behavior in the B parameter. Such a...
Cosmology of Antisymmetric Tensor Field in D-brane Universe (2005)
Chun, Eung Jin, Kim, Hang Bae, Kim, Yoonbai
We analyze homogeneous, anisotropic cosmology driven by a self-interacting ``massive'' antisymmetric tensor field $B_{\mu\nu}$ which is present in string theories with D-branes. Time-dependent...
A Predictive Seesaw Scenario for EDMs (2005)
Chun, Eung Jin, Masiero, Antonio, Rossi, Anna, Vempati, Sudhir K.
The generation of electric dipole moments (EDMs) is addressed in the supersymmetric seesaw scenario realized through the exchange of SU(2)_W triplet states. In particular, we show that the triplet...
Curvaton and QCD axion in supersymmetric theories. (2004)
Chun, Eung Jin, Dimopoulos , Konstantinos, Lyth , David H.
A pseudo-Nambu-Goldstone boson as curvaton avoids the η problem of inflation which plagues most curvaton candidates. We point out that a concrete realization of the curvaton mechanism with a...
Neutrino Mass from R-parity Violation in Split Supersymmetry (2004)
Chun, Eung Jin, Park, Seong Chan
We investigate how the observed neutrino data can be accommodated by R-parity violation in Split Supersymmetry. The atmospheric neutrino mass and mixing are explained by the bilinear parameters...
Neutrino Oscillations and Collider Test of the R-parity Violating Minimal Supergravity Model (2004)
Jung, Dong-Won, Kang, Sin Kyu, Park, Jong Dae, Chun, Eung Jin
We study the R-parity violating minimal supergravity models accounting for the observed neutrino masses and mixing, which can be tested in future collider experiments. The bi-large mixing can be...
Late Leptogenesis from Radiative Soft Terms (2004)
We point out that the so-called ``soft leptogenesis'' can occur at TeV scale if the $B$ term is generated through radiative corrections which involve two-loop diagrams with the gaugino exchange. This...
Curvaton and QCD Axion in Supersymmetric Theories (2004)
Chun, Eung Jin, Dimopoulos, Konstantinos, Lyth, David
A pseudo Nambu-Goldstone boson as curvaton avoids the eta-problem of inflation which plagues most curvaton candidates. We point out that a concrete realization of the curvaton mechanism with a pseudo...
Chun, Eung Jin, Jung, Dong-Won, Kang, Sin Kyu, Park, Jong Dae
We study the correlation between the neutrino oscillation and the production/decay of the lightest supersymmetric particle(LSP) in the context of the minimal supergravity model(mSUGRA) without...
Supersymmetric threshold corrections to \Delta m^2_{\odot} (2003)
Brahmachari, Biswajoy, Chun, Eung Jin
For nearly degenerate neutrinos, quantum corrections can modify the tree-levelmasses via low energy supersymmetric threshold corrections comparable to the solar oscillation mass scale. We numerically...
Wrong-sign Kaons in B decays and New Physics (2003)
New physics can possibly emerge in the B decays into wrong-sign kaons for which the standard model contributions are extremely suppressed. We analyze two-body decays of $\bar{B}^0$ and $B^-$ mesons...
Testing Higgs Triplet Model and Neutrino Mass Patterns (2003)
Chun, Eung Jin, Lee, Kang Young, Park, Seong Chan
The observed neutrino oscillation data might be explained by new physics at a TeV scale, which is testable in the future experiments. Among various possibilities, the low-energy Higgs triplet model...
Bi-maximal neutrino mixing and small U_{e3} from Abelian flavor symmetry (2001)
Choi, Kiwoon, Chun, Eung Jin, Hwang, Kyuwan, Song, Wan Young
Atmospheric neutrino data strongly suggests a near-maximal \nu_\mu-\nu_{\tau} mixing and also solar neutrino data can be nicely explained by another near-maximal \nu_e-\nu_{\mu} or \nu_e-\nu_{\tau}...
In supersymmetric theories, sneutrino--anti-sneutrino mixing can occur with the oscillation time $\sim 0.01$ ps corresponding the atmospheric neutrino mass scale $\sim 0.05$ eV. We explore the...
Lepton Flavor Violation and Radiative Neutrino Masses (2001)
Lepton flavor violation in various sectors of the theory can bring important effects on neutrino masses and mixing through wave function renormalization. We examine general conditions for flavor...
Axino as a sterile neutrino and R parity violation (2001)
Choi, Kiwoon, Chun, Eung Jin, Hwang, Kyuwan
We point out that axino can be a natural candidate for sterile neutrino which would accommodate the LSND data with atmospheric and solar neutrino oscillations. It is shown that the so called 3+1...
The abundance of relativistic axions in a flaton model of Peccei-Quinn symmetry (2000)
Chun, Eung Jin, Comelli, Denis, Lyth, David H.
Flaton models of Peccei-Quinn symmetry have good particle physics motivation, and are likely to cause thermal inflation leading to a well-defined cosmology. They can solve the $\mu$ problem, and...
Cosmological constraints on a Peccei-Quinn flatino as the lightest supersymmetric particle (2000)
Chun, Eung Jin, Kim, Hang Bae, Lyth, David H.
In an interesting class of models, non-renormalizable terms of the superpotential are responsible for the spontanteous breaking of Peccei-Quinn (PQ) symmetry as well as the generation of the $\mu$...
Lepton Flavor Violation and Bilinear R-parity Violation (2000)
Choi, Kiwoon, Chun, Eung Jin, Hwang, Kyuwan
We examine some flavor changing processes such as rare leptonic decays of the long-lived neutral kaon, muon-electron conversion in nuclei and radiative muon decay which are induced by the combined...
CP Asymmetries in Radiative B Decays with R-parity Violation (2000)
Chun, Eung Jin, Hwang, Kyuwan, Lee, Jae Sik
We analyze the effect of R-parity violation in the minimal supersymmetric standard model on the CP asymmetries in $b\to s \gamma$ decay. The direct and mixing-induced CP asymmetries arising from the...
Fermion Electric Dipole Moments in Supersymmetric Models with R-parity Violation (2000)
Choi, Kiwoon, Chun, Eung Jin, Hwang, Kyuwan
We analyze the electron and neutron electric dipole moments induced by R-parity violating interactions in supersymmetric models. It is pointed out that dominant contributions can come from one-loop...
Baryogenesis and Degenerate Neutrinos (2000)
We bring the theoretical issue of whether two important cosmological demands, baryon asymmetry and degenerate neutrinos as hot dark matter, can be compatible in the context of the seesaw mechanism....
R-parity Violation and Neutrino Masses (2000)
R-parity violation in the supersymmetric standard model could be the origin of neutrino masses and mixing accounting for the atmospheric and solar neutrino oscillations. More interestingly, this...
Radiative Splitting of Three Degenerate Neutrinos (1999)
We propose a radiative origin of the two mass splittings of three degenerate Majorana neutrinos. It can be achieved by extending the standard model to have the usual effective dimension 5 operators...
Slepton Flavour Mixing and Neutrino Masses (1999)
Chun, Eung Jin, Pokorski, Stefan
It is pointed out that important contribution to neutrino masses and mixing can come from flavour violating slepton exchange. For low and intermediate $\tan\beta$ such effects can dominate over the...
We provide, in the R-parity violating supersymmetric standard model, a comprehensive analysis for sneutrino minimization from the one-loop effective scalar potential, and also for one-loop...
Nonthermal Axino as Cool Dark Matter in Supersymmetric Standard Model without R-parity (1999)
We point out that the axino predicted as the supersymmetric partner of the axion is a good candidate for the recently proposed sterile neutrino cool dark matter. The axino mass falls into the right...
Neutrino Oscillations and R-parity Violating Collider Signals (1999)
Choi, S. Y., Chun, Eung Jin, Kang, Sin Kyu, Lee, Jae Sik
R-parity and L violation in the MSSM would be the origin of the neutrino oscillation observed in Super-Kamiokande. A distinctive feature of this framework is that it can be tested in colliders by...
Axino-Neutrino Mixing in Gauge-Mediated Supersymmetry Breaking Models (1999)
When the strong CP problem is solved by spontaneous breaking of an anomalous global symmetry in theories with gauge-mediated supersymmetry breaking, the pseudo Goldstone fermion (the axino) is a good...
Atmospheric and Solar Neutrino Masses from Horizontal U(1) Symmetry (1998)
Choi, Kiwoon, Chun, Eung Jin, Hwang, Kyuwan
We study the neutrino mass matrix in supersymmetric models in which the quark and charged lepton mass hierarchies and also the suppression of baryon or lepton number violating couplings are all...
Implication of Super-Kamiokande Data on R-parity Violation (1998)
R-parity violating bilinear (soft) terms in the supersymmetric standard model would be the leading source for nonzero neutrino masses and mixing. We point out that the mixing between neutralinos...
Cosmology of Light Moduli (1998)
Choi, Kiwoon, Chun, Eung Jin, Kim, Hang Bae
In string/M-theory with a large compactification radius, some axion-like moduli can be much lighter than the gravitino. Generic moduli in gauge-mediated supersymmetry breaking models also have a mass...
Strong CP and Mu Problems in Theories with Gauge Mediated Supersymmetry Breaking (1997)
We provide a simple solution to the $\mu$ and strong CP problems in the context of gauge mediated supersymmetry breaking. The generic appearance of R symmetry in dynamical supersymmetry breaking is...
Gauge Unification and Dynamical Supersymmetry Breaking (1997)
Chun, Eung Jin, Lee, Haewon, L'Yi, Won Sik
Under the assumption that all the gauge groups in supersymmetric theories unify at the fundamental scale, the numbers and the mass scales of messenger quarks and leptons, as well as the beta-function...
Supersymmetry Hierarchy Problems and Anomalous Horizontal U(1) Symmetry (1996)
Choi, Kiwoon, Chun, Eung Jin, Kim, Hyungdo
It is suggested that various hierarchy problems in supersymmetric standard model, i.e. the Yukawa hierarchies, the \mu problem, and the suppression of dangerous baryon and/or lepton number (B/L)...
Proton Decay with a Light Gravitino or Axino (1996)
Choi, Kiwoon, Chun, Eung Jin, Lee, Jae Sik
We consider the proton decay in supersymmetric models with a gravitino or axino lighter than the proton. This consideration leads to a stringent limit on the R parity and B violating Yukawa coupling...
The $\mu$ problem, and B and L Conservation with a Discrete Gauge R Symmetry (1996)
Choi, Kiwoon, Chun, Eung Jin, Kim, Hyungdo
We examine in a generic context how the $\mu$ problem can be resolved by means of a spontaneously broken gauge symmetry. We then focus on the new scheme based on a discrete gauge R symmetry which is...
Gauged R-symmetry, Fermion and Higgs Mass Problem (1995)
We consider the simplest model of $SU(3) \times SU(2) \times U(1)_Y \times U(1)_R$ gauge symmetry with one extra singlet field whose vacuum expectation value breaks the horizontal $R$-symmetry...
Dark Matters in Axino Gravitino Cosmology (1993)
Chun, Eung Jin, Kim, Hang Bae, Kim, Jihn E.
It is suggested that the axino mass in the 1 MeV region and gravitino mass in the eV region can provide an axino lifetime of order of the time of photon decoupling. In this case, some undecayed...