Results for "Pyungwon Ko"

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$η\to π^{0} γγ$ and $γγ\to π^{0} π^{0}$ in $O(p^{6})$ chiral perturbation theoryMar 07 1995$\eta \rightarrow \pi^{0} \gamma \gamma$ and $\ggpipi$ are considered in $O(p^{6})$ chiral perturbation theory. In addition to the usual $\rho,\omega$ contributions, there are two $O(p^{6})$ operators (${\cal L}_{6,m}$) arising from explicit chiral symmetry ... More
Electroweak symmetry breaking and cold dark matter from hidden sector technicolorJan 28 2008We consider models with a vectorlike confining gauge theory in the hidden sector, and demonstrate that the origin of the electroweak symmetry breaking (EWSB) is due to the dimensional transmutation in the hidden sector gauge theory, and the lightest mesons ... More
Recent Developments In Heavy Quarkonium PhysicsFeb 21 1998Recent developments in heavy quarknoium physics are reviewed in brief, including (i) nonrelativistic QCD(NRQCD), (ii) the importance of color-octet $(Q\bar{Q})$ components in the decay and the production of a physical heavy quarkonium state, (iii) limitation ... More
Phenomenology of $U(1)_{L_μ- L_τ}$ charged dark matter at PAMELA/FERMI and collidersNov 11 2008Sep 16 2009Recent data on $e^+/e^-$ and $\bar{p}$ cosmic rays suggest that dark matter annihilate into the standard model (SM) particles through new leptophilic interaction. In this paper, we consider a standard model extension with the gauged $U(1)_{L_\mu - L_\tau}$ ... More
MSSM Anatomy of the Polarization Puzzle in B --> phi K* DecaysNov 10 2005Feb 03 2006We analyze the $B \to \phi K^{*}$ polarization puzzle in the Minimal Supersymmetric Standard Model (MSSM) including the neutral Higgs boson (NHB) contributions. To calculate the non-factorizable contributions to hadronic matrix elements of operators, ... More
Supersymmetric U(1)B x U(1)L model with leptophilic and leptophobic cold dark mattersDec 20 2010Jun 07 2011We consider a supersymmetric model with extra $U(1)_B \times U(1)_L$ gauge symmetry that are broken spontaneously. Salient features of this model are that there are three different types of cold dark matter (CDM) candidates, and neutral scalar sector ... More
Probing SUSY-induced CP violations at B factoriesDec 02 1998Jun 13 1999In the minimal supersymmetric standard model (MSSM), the \mu-parameter and the trilinear coupling A_t may be generically complex and can affect various observables at B factories. Imposing the edm constraints, we find that there is no new large phase ... More
Effects of supersymmetric CP violating phases on B \to X_s l^+ l^- and ε_KApr 09 1999We consider effects of CP violating phases in \mu and A_t parameters in the effective supersymmetric standard model on B\to X_s l^+ l^- and \epsilon_K. Scanning over the MSSM parameter space with experimental constraints including edm constraints from ... More
A new method for extracting the weak phase gamma from B ---> D K(*) decaysJul 27 1998A new method to extract the weak phase $\gamma$ is suggested by exploiting B ---> D K^{(*)} decay modes that are not Cabibbo suppressed, using the isospin relations, and ignoring the annihilation diagram as usual. Assuming $3 \times 10^8 B\bar{B}$ pair ... More
Flavor $SU(3)$ properties of beauty tetraquark states with three different light quarksMar 09 2016May 15 2016Beauty tetraquark states $X(\bar b q'q'' \bar q )$ composed of $ \bar b s u \bar d$, $\bar b d s \bar u$, and $\bar b u d \bar s$, are unique that all the four valence quarks are different. Although the claim of existence of the first two states by D0 ... More
Color-octet mechanism in $γ+ p \to J/ψ+ X$Feb 05 1996Aug 21 1999Photoproduction of $J/\psi$ is considered including the color-octet contributions from the various partial wave states, $^{2S+1}L_J$ = $^1S_0$, $^3S_1$ and $^3P_J$. The production cross section depends on three new nonperturbative parameters defined in ... More
Sflavor mixing map viewed from a high scale in supersymmetric SU(5)Sep 16 2008Sep 28 2008We study flavor violation in a supersymmetric SU(5) grand unification scenario in a model-independent way employing mass insertions. We examine how the quark and the lepton sector observables restrict sfermion mixings. With a low soft scalar mass, a lepton ... More
Final-state ππinteractions in Υ(3S)\rightarrowΥ(1S)ππOct 29 1993The $m_{\pi\pi}$ spectrum and various angular distributions in $\upss$ are studied including the effects of the $\pi\pi$ phase shift in the $I=L=0$ channel using the lowest order amplitude in the pion momentum expansion. Our results are compared with ... More
Is Upsilon(3S) a pure S-wave?Jan 19 1993Assuming the QCD multipole expansion is applicable to hadronic transitions of Upsilon(3S) into lower level bottomonia, we consider the possibility that Upsilon(3S) has a D-wave component. This assumption leads to a natural explanation of the pi-pi spectrum ... More
Stable Higgs Bosons as Cold Dark MatterAug 03 2009In a class of the gauge-Higgs unification models the 4D neutral Higgs boson, which is a part of the extra-dimensional component of the gauge fields, becomes absolutely stable as a consequence of the gauge invariance and dynamically generated new parity, ... More
Color-octet mechanism in the inclusive D-wave charmonium productions in B decaysJan 07 1997The inclusive D-wave charmonium production rates in B decays are considered in the Bodwin-Braaten-Lepage (BBL) approach. We find that the color-octet subprocesses B->cc_(^3S_1^(8) or ^3P_J^(8))+s,d, followed by the transition cc_(^3S_1^(8) or ^3P_J^(8)) ... More
Quark masses and mixing angles in heterotic orbifold modelsJun 03 2004Jun 15 2004We study systematically the possibility for realizing realistic values of quark mass ratios $m_c/m_t$ and $m_s/m_b$ and the mixing angle $V_{cb}$ by using only renormalizable Yukawa couplings derived from heterotic orbifold models. We assume one pair ... More
Top-philic Scalar Dark Matter with a Vector-like Fermionic Top PartnerMay 31 2016Oct 21 2016We consider a simple extension of the Standard Model with a scalar top-philic Dark Matter (DM) $S$ coupling, apart from the Higgs portal, exclusively to the right-handed top quark $t_R$ and a colored vector-like top partner $T$ with a Yukawa coupling ... More
Top-philic Scalar Dark Matter with a Vector-like Fermionic Top PartnerMay 31 2016Sep 27 2016We consider a simple extension of the Standard Model with a scalar top-philic Dark Matter (DM) $S$ coupling, apart from the Higgs portal, exclusively to the right-handed top quark $t_R$ and a colored vector-like top partner $T$ with a Yukawa coupling ... More
Chiral perturbation theory vs. vector meson dominance in the decays $φ\to ργγ$ and $φ\to ωγγ$Oct 02 1995It is pointed out that the radiative decays of a $\phi$ meson, $\phirho$ and $\phiom$, receive dominant contributions from the pseudoscalar ($P = \eta, \eta^{'}$) exchanges. Using the vector meson dominance model, we find that $B (\phirho) \approx 1.3 ... More
Higgs-portal assisted Higgs inflation with a sizeable tensor-to-scalar ratioMay 07 2014Oct 11 2016We show that the Higgs portal interactions involving extra dark Higgs field can save generically the original Higgs inflation of the standard model (SM) from the problem of a deep non-SM vacuum in the SM Higgs potential. Specifically, we show that such ... More
An alternative to the standard modelOct 23 2013We present an extension of the standard model to dark sector with an unbroken local dark $U(1)_X$ symmetry. Including various singlet portal interactions provided by the standard model Higgs, right-handed neutrinos and kinetic mixing, we show that the ... More
AdS/QCD approach to the scale-invariant extension of the standard model with a strongly interacting hidden sectorJun 09 2016Aug 19 2016In this paper, we revisit a scale-invariant extension of the standard model (SM) with a strongly interacting hidden sector within AdS/QCD approach. Using the AdS/QCD, we reduce the number of input parameters to three, {\it i.e.} hidden pion decay constant, ... More
Light dark matter in leptophobic Z' modelsJun 05 2011Recent experimental results in direct dark matter detection may be interpreted in terms of a dark matter particle of mass around 10 GeV/c^2. We show that the required scenario can be realized with a new dark matter particle charged under an extra abelian ... More
Inclusive $S-$wave charmonium productions in $B$ decaysOct 02 1995The inclusive $S-$wave charmonium production rates in $B$ decays are considered using the Bodwin-Braaten-Lepage (BBL) approach, including the relativistic corrections and the color-octet mechanism suggested as a possible solution to the $\psi^{'}$ puzzle ... More
A simple modification of the maximal mixing scenario for three light neutrinosMar 26 1995Aug 16 1996We suggest a simple modification of the maximal mixing scenario (with $S_3$ permutation symmetry) for three light neutrinos. Our neutrino mass matrix has smaller permutation symmetry $S_{2}$ ($\nu_{\mu} \leftrightarrow \nu_{e}$), and is consistent with ... More
Lepton masses and mixing angles from heterotic orbifold modelsMar 03 2005May 02 2005We systematically study the possibility for realizing realistic values of lepton mass ratios and mixing angles by using only renormalizable Yukawa couplings derived from heterotic $Z_6$-I orbifold. We assume one pair of up and down sector Higgs fields. ... More
Heavy quark-philic scalar dark matter with a vector-like fermion portalSep 03 2017Jul 02 2018In this work we consider a real scalar dark matter $S$ interacting only with $SU(2)_L$ singlet Up-type quarks $U_i=u_R,c_R,t_R$ via a vector-like fermion $\psi$ which has the same quantum number as $U_i$. The DM-nucleon scattering can proceed through ... More
String-derived D4 flavor symmetry and phenomenological implicationsApr 21 2007In this paper we show how some flavor symmetries may be derived from the heterotic string, when compactified on a 6D orbifold. In the body of the paper we focus on the $D_4$ family symmetry, recently obtained in $Z_3 \times Z_2$ orbifold constructions. ... More
$a_1 (1260)$ contribution to photon and dilepton productions from hot hadronic matter : RevisitedFeb 15 1996We consider the $a_{1} (1260)$ contribution to photon and dilepton productions from hot hadronic matter. The effective lagrangian with $\pi, \rho$ and $a_{1}$ discussed by Ko and Rudaz is employed, which successfully reproduces the $\Gamma (a_{1} \rightarrow ... More
More on R-parity and lepton-family number violating couplings from muon(ium) conversion, and τand $π^0$ decaysJan 27 1997We present a new class of constraints to the lepton-family number and R-parity violating couplings from muonium conversion, $\mu^{-} + {_{22}^{48}} Ti \to e^{-} + {_{22}^{48}} Ti$, a class of tau decays, $\tau \to l +$ (light meson) with $l= \mu or e$, ... More
Measuring $|V_{ub}|$ at future B-FactoriesMar 18 1994We calculate the so--called Fermi motion parameter $p_{_F}$ of ACCMM model using the variational method in a potential model approach. We also propose hadronic invariant mass distribution as an alternative experimental observable to measure $V_{ub}$ at ... More
Gravitational waves from first order electroweak phase transition in models with the $U(1)_X^{}$ gauge symmetryFeb 08 2018We consider a standard model extension equipped with a dark sector where the $U(1)_X^{}$ Abelian gauge symmetry is spontaneously broken by the dark Higgs mechanism. In this framework, we investigate patterns of the electroweak phase transition as well ... More
Partially composite two-Higgs doublet modelOct 06 2005Dec 22 2005In the extra dimensional scenarios with gauge fields in the bulk, the Kaluza-Klein (KK) gauge bosons can induce Nambu-Jona-Lasinio (NJL) type attractive four-fermion interactions, which can break electroweak symmetry dynamically with accompanying composite ... More
New Approach for Measuring $|V_{ub}|$ at Future $B$-FactoriesJun 08 1994It is suggested that the measurements of hadronic invariant mass ($m_X$) distributons in the inclusive $B \rightarrow X_{c(u)} l \nu$ decays can be useful in extracting the CKM matrix element $|V_{ub}|$. We investigated hadronic invariant mass distributions ... More
Hidden sector dark matter and Higgs physicsJan 09 2013We consider a hidden sector dark matter, where a singlet fermion is a cold dark matter and a real singlet scalar boson $S$ is a messenger between the SM and the hidden sectors. This singlet scalar will mix with the SM Higgs boson $h$, and we expect there ... More
Gravitational waves and Higgs boson couplings for exploring first order phase transition in the model with a singlet scalar fieldSep 01 2016We calculate the spectrum of gravitational waves originated from strongly first order electroweak phase transition in the extended Higgs model with a real singlet field. In order to calculate the bubble nucleation rate, we perform a two-field analysis ... More
Almost maximally broken permutation symmetry for neutrino mass matrixNov 19 1996Assuming three light neutrinos are Majorana particles, we propose mass matrix ansatz for the charged leptons and Majorana neutrinos with family symmetry $S_{3} $ broken into $S_{1}$ and $S_{2}$, respectively. Each matrix has three parameters, which are ... More
Unitarizing SIMP scenario with dark vector resonancesNov 07 2018Dark pion is the one of the most natural and realistic model to make $3 \rightarrow 2$ contact interactions among models of the Strongly Interacting Massive Particle (SIMP). In this model, there is a perturbativity problem to satisfy the relic density ... More
$K_{L e5}$ decay as a background in search for $K_{L} \to π^{0} μ^{\pm} e^{\mp}$Feb 16 1995Feb 18 1995We consider a process $K_{L e5} ( K_{L} \rightarrow \pi^{0} \pi^{0} \pi^{\pm} e^{\mp} \nu )$ as a standard model background to the experiment $K_{L} \rightarrow \pi^{0} \mu^{\pm} e^{\mp}$, which seeks for possible violation of lepton family number. Using ... More
Revisiting T2KK and T2KO physics potential and $ν_μ$ - $\barν_μ$ beam ratioMay 08 2016Sep 28 2016We revisit the sensitivity study of the Tokai-to-Kamioka-and-Korea (T2KK) and Tokai-to-Kamioka-and-Oki (T2KO) proposals where a water Cerenkov detector with the 100 kton fiducial volume is placed in Korea ($L = 1000$ km) and Oki island ($L = 653$ km) ... More
B decays into two light pseudoscalar mesons and possible effects of enhanced b --> s gOct 15 1998We consider the branching ratios and CP asymmetry in the B meson decays into two pseudoscalar mesons in the generalized factorization approximation. We also investigate the possible effects of the enhanced chromomagnetic interaction b --> s g on these ... More
Mass Matrix Ansatz for Degenerate Neutrinos Consistent with Solar and Atmospheric neutrino DataJun 28 1997Oct 09 1998We suggest mass matrices for neutrinos and charged leptons that can explain solar and atmospheric neutrino data. The resulting flavor mixing matrix $V_{\nu}$ has a property that $(V_{\nu})_{13}=0$, thus making $\nu_e \leftrightarrow \nu_{\mu}$ and $\nu_{\mu} ... More
Correlation between $R_{D^{(*)}}$ and top quark FCNC decays in leptoquark modelsDec 20 2018Jan 23 2019Some interpretations of $R_{D^{(*)}}$ anomaly in $B$ meson decay using leptoquark models can also generate top quark decays through flavor changing neutral current (FCNC). In this work we focus on two leptoquarks, i.e. scalar $S_1$ and vector $U_1$ which ... More
Inclusive Production of Four Charm Hadrons in e^+ e^- Annihilation at B FactoriesDec 16 2004Mar 24 2005Measurements by the Belle Collaboration of the exclusive production of two charmonia in e^+ e^- annihilation differ substantially from theoretical predictions. Till now, no conclusive explanation for this remarkable discrepancy has been provided. Even ... More
Probing Nonstandard Neutrino Physics by Two Identical Detectors with Different BaselinesDec 28 2007The Kamioka-Korea two detector system is a powerful experimental setup for resolving neutrino parameter degeneracies and probing CP violation in neutrino oscillation. In this paper, we study sensitivities of this same setup to several nonstandard neutrino ... More
Complete analysis of photino-mediated lepton flavor violaitons in generalized supersymmetric modelsNov 02 1998We consider lepton flavor violations (LFV) mediated by photino as a result of the nondiagonal slepton mass matrices in general supersymmetric models. Using the experimental upper bounds on l \to l' + gamma and mu^- + Ti \to e^- + Ti as constraints on ... More
Non-Standard Neutrino Physics Probed by Tokai-to-Kamioka-Korea Two-Detector ComplexJan 16 2008The discovery potentials of non-standard physics (NSP) which might be possessed by neutrinos are examined by taking a concrete setting of Tokai-to-Kamioka-Korea (T2KK) two detector complex which receives neutrino superbeam from J-PARC. We restrict ourselves ... More
Schrödinger Fields on the Plane with $[U(1)]^N$ Chern-Simons Interactions and Generalized Self-dual SolitonsMar 24 1993A general non-relativistic field theory on the plane with couplings to an arbitrary number of abelian Chern-Simons gauge fields is considered. Elementary excitations of the system are shown to exhibit fractional and mutual statistics. We identify the ... More
Color-evaporation-model calculation of e^+ e^- -> J/psi+cc-bar+X at root-s=10.6 GeVDec 26 2004May 18 2005Measurements by the Belle Collaboration of the cross section for inclusive J/psi production in e^+e^- annihilation have been a serious challenge to current heavy-quarkonium theory. Especially, the measured cross sections for exclusive J/psi+eta_c and ... More
Equivalence of the (generalised) Hadamard and microlocal spectrum condition for (generalised) free fields in curved spacetimeMar 05 2009We prove that the singularity structure of all n-point distributions of a state of a generalised real free scalar field in curved spacetime can be estimated if the two-point distribution is of Hadamard form. In particular this applies to the real free ... More
Local vs. global temperature under a positive curvature conditionMay 03 2016For a massless free scalar field in a globally hyperbolic space-time we compare the global temperature T, defined for the KMS states $\omega^T$, with the local temperature $T_{\omega}(x)$ introduced by Buchholz and Schlemmer. We prove the following claims: ... More
Relativistic Hubble's lawMar 16 2003Considering the hyperbolic nature of the universe, the Hubble's law and the inverse square laws such as, the Coulomb's law and Newton's gravitational law, should be modified in accordance with the special theory of relativity. Consequently there is no ... More
Free Energy of Multiple Systems of Spherical Spin Glasses with Constrained OverlapsJun 26 2018The free energy of multiple systems of spherical spin glasses with constrained overlaps was first studied in arXiv:math/0604082. The authors proved an upper bound of the constrained free energy using Guerra's interpolation. In this paper, we prove this ... More
The Construction of a Partially Regular Solution to the Landau-Lifshitz-Gilbert Equation in $\mathbb{R}^2$Dec 30 2004We establish a framework to construct a global solution in the space of finite energy to a general form of the Landau-Lifshitz-Gilbert equation in $\mathbb{R}^2$. Our characterization yields a partially regular solution, smooth away from a 2-dimensional ... More
Cohomology in singular blocks for a quantum group at a root of unityMay 15 2016Jun 02 2016Let $U_\zeta$ be a Lusztig quantum enveloping algebra associated to a complex semisimple Lie algebra $\mathfrak g$ and a root of unity $\zeta$. When $L,L'$ are irreducible $U_\zeta$-modules having regular highest weights, the dimension of $\operatorname{Ext}^n_{U_\zeta}(L,L')$ ... More
Why is nacre strong? II: remaining mechanical weakness for cracks propagating along the sheetsMar 12 2002In our previous paper (Eur. Phys. J. E 4, 121 (2001)) we proposed a coarse-grained elastic energy for nacre, or stratified structure of hard and soft layers. We then analyzed a crack running perpendicular to the layers and suggested one possible reason ... More
Zero-Bias States and the Mechanism of the Surface d->d+is TransitionAug 28 2000We study the physical mechanism of the surface d->d+is transition proposed as the interpretation of results of tunneling experiments into ab planes. We base our argument on first-order perturbation theory and show that the zero-bias states drive the transition. ... More
Thermal equilibrium states of a linear scalar quantum field in stationary spacetimesSep 26 2012Apr 12 2013The linear scalar quantum field, propagating in a globally hyperbolic spacetime, is a relatively simple physical model that allows us to study many aspects in explicit detail. In this review we focus on the theory of thermal equilibrium (KMS) states of ... More
The topology and geometry of contact structures in dimension threeJan 07 2006The goal of this article is to survey recent developments in the theory of contact structures in dimension three.
Gluing tight contact structuresFeb 04 2001We prove gluing theorems for tight contact structures. In particular, we rederive (as special cases) gluing theorems due to Colin and Makar-Limanov, and present an algorithm for determining whether a given contact structure on a handlebody is tight. As ... More
Local Properties of Self-Dual Harmonic 2-forms on a 4-ManifoldMay 30 1997May 31 1997We will prove a Moser-type theorem for self-dual harmonic 2-forms on closed 4-manifolds, and use it to classify local forms on neighborhoods of singular circles on which the 2-form vanishes. Removing neighborhoods of the circles, we obtain a symplectic ... More
A note on spacelike and timelike compactnessNov 11 2012When studying the causal propagation of a field in a globally hyperbolic spacetime M, one often wants to express the physical intuition that it has compact support in spacelike directions, or that its support is a spacelike compact set. We compare a number ... More
EW scale DM models with dark gauge symmetriesApr 30 2016In this talk, I describe a class of electroweak (EW) scale dark matter (DM) models where its stability or longevity are the results of underlying dark gauge symmetries: stable due to unbroken local dark gauge symmetry or topology, or long-lived due to ... More
Dark matter, dark radiation and Higgs phenomenology in the hidden sector DM modelsMar 18 2015I present a class of hidden sector dark matter (DM) models with local dark gauge symmetries, where DM is stable due to unbroken local dark gauge symmetry, or due topology, or it is long-lived because of some accidental symme- tries, and the particle contents ... More
Electroweak symmetry breaking and cold dark matter from strongly interacting hidden sectorDec 01 2010We consider a hidden sector with new vectorlike confining gauge theories like QCD. Then a scale $\Lambda_H$ would be generated in the hidden sector by dimensional transmutation, and chiral symmetry breaking occurs in the hidden sector. Then this scale ... More
Effects of flavor conserving CP violating phases in SUSY modelsFeb 26 2000I summarize our recent works on the effects of flavor conserving CP violating phases in SUSY models on $B$ and $K$ phenomenology.
Contribution of $b\to s gg$ through the QCD anomaly in exclusive decays $B \to (η',η) (K, K^{*})$Oct 09 1998The charm content in $\eta'$ is estimated using the QCD U(1) axial anomaly applied to $b\to s g g \to \eta' s$. We find $f_{\eta'}^{(c)} \approx - 3.1$ MeV for $m_c = 1.3$ GeV. Our estimate agrees with other independent methods by Feldmann and Kroll, ... More
Search for $η_{c}^{'}$ and $h_{c} (^{1}P_{1})$ states in the $e^+ e^-$ annihilationsMay 13 1995Productions and decays of spin-singlet $S,P-$wave charmonium states, $\eta_{c}^{'}$ and $h_{c} (^{1}P_{1})$, in the $e^+ e^-$ annihilations are considered in the QCD multipole expansion with neglecting nonlocality in time coming from the color-octet intermediate ... More
On the classification of tight contact structures IOct 24 1999Nov 29 2001We develop new techniques in the theory of convex surfaces to prove complete classification results for tight contact structures on lens spaces, solid tori, and T^2 X I. Erratum: In this note we seek to remedy errors which appeared in version 2 and were ... More
On the construction of Hartle-Hawking-Israel states across a static bifurcate Killing horizonOct 21 2013Jan 29 2015We consider a linear scalar quantum field propagating in a space-time with a static bifurcate Killing horizon and a wedge reflection. We prove the existence of a Hadamard state which is pure, quasi-free, invariant under the Killing flow and which restricts ... More
Essential self-adjointness of Wick squares in quasi-free Hadamard representations on curved spacetimesOct 19 2010Apr 06 2012We investigate whether a second order Wick polynomial T of a free scalar field, including derivatives, is essentially self-adjoint on the natural (Wightman) domain in a quasi-free (i.e. Fock space) Hadamard representation. We restrict our attention to ... More
The locally covariant Dirac fieldNov 06 2009Nov 11 2009We describe the free Dirac field in a four dimensional spacetime as a locally covariant quantum field theory in the sense of Brunetti, Fredenhagen and Verch, using a representation independent construction. The freedom in the geometric constructions involved ... More
Viscoelastic fractures in stratified composite materials: "lenticular trumpet"Dec 04 2002We consider fractures in a stratified composite material with solid layers separated by thin slices of extremely soft matter. Viscoelastic effects associated with the soft layers are taken into account via the simplest model for weakly cross-linked polymers. ... More
Physical picture for fractures in stratified materials: viscoelastic effects in large cracksDec 20 2002We present an intuitive physical picture for fractures in nacre-type stratified materials via scaling arguments: strain distributions around a fracture are rather different depending on directions and size of fractures. We thus observe that viscoelastic ... More
Aspects of locally covariant quantum field theorySep 28 2008This thesis considers various aspects of locally covariant quantum field theory (LCQFT; see Brunetti et al., Commun.Math.Phys. 237 (2003), 31-68), a mathematical framework to describe axiomatic quantum field theories in curved spacetimes. New results ... More
Grade zero part of forced graded algebrasSep 14 2017The paper concerns a certain subcategory of the category of representations for a semisimple algebraic group $G$ in characteristic $p$, which arise from the semisimple modules for the corresponding quantum group at a $p$-th root of unity. The subcategory, ... More
The supergroup U(M/N) with regard to electronic HamiltoniansFeb 18 1993We study the U(M/N) supergroup keeping in mind its connection with electronic Hamiltonians. It is explicitly shown that the generators of the supergroup U(N/N) can be expressed by Clifford operators or Fermi operators. A multi-band supersymmetric electronic ... More
Derivation of a Quark Confinement Potential from QCDJan 12 1999Mar 31 1999A quark confinement potential is derived from QCD Lagrangial under the two assumptions in the energy region relevant to quark confinement. The possibility of perturbation in QCD is assumed, and the momentum of the gluon transfered by the quark is larger ... More
Hyperbolic triangle in the special theory of relativityApr 15 2002The vector form of a Lorentz transformation which is separated with time and space parts is studied. It is necessary to introduce a new definition of the relative velocity in this transformation, which plays an important role for the calculations of various ... More
The charge radii and the decay rates of the pseudoscalar mesonAug 17 1999The charge radii and the decay rates of the pion and kaons are calculated, using the relativistic equation of motion with a linear potential. Those physical quantities are quite well explained with the current quark masses in the case of the pion. It ... More
3-dimensional methods in contact geometryJan 14 2004These are lecture notes on cut-and-paste methods in 3-dimensional contact geometry.
On the Reeh-Schlieder Property in Curved SpacetimeJan 30 2008We attempt to prove the existence of Reeh-Schlieder states on curved spacetimes in the framework of locally covariant quantum field theory using the idea of spacetime deformation and assuming the existence of a Reeh-Schlieder state on a diffeomorphic ... More
On modules arising from quantum groups at $p^r$-th roots of unityJun 27 2016Jul 01 2016This paper studies the "reduction mod $p$" method, which constructs large classes of representations for a semisimple algebraic group $G$ from representations for the corresponding Lusztig quantum group $U_\zeta$ at a $p^r$-th root of unity. The $G$-modules ... More
Cohomology in singular blocks for a quantum group at a root of unityMay 15 2016Jul 12 2018Let $U_\zeta$ be a Lusztig quantum enveloping algebra associated to a complex semisimple Lie algebra $\mathfrak g$ and a root of unity $\zeta$. When $L,L'$ are irreducible $U_\zeta$-modules having regular highest weights, the dimension of $\operatorname{Ext}^n_{U_\zeta}(L,L')$ ... More
Local vs. global temperature under a positive curvature conditionMay 03 2016Aug 14 2017For a massless free scalar field in a globally hyperbolic space-time we compare the global temperature T, defined for the KMS states $\omega^T$, with the local temperature $T_{\omega}(x)$ introduced by Buchholz and Schlemmer. We prove the following claims: ... More
Photon-number tomography of multimode states and positivity of the density matrixMar 06 2019For one-mode and multimode light, the photon-number tomograms of Gaussian quantum states are explicitly calculated in terms of multivariable Hermite polynomials. Positivity of the tomograms is shown to be necessary condition for positivity of the density ... More
Residual Non-Abelian Dark Matter and Dark RadiationSep 08 2016We propose a novel particle physics model in which vector dark matter (VDM) and dark radiation (DR) originate from the same non-Abelian dark sector. We show an illustrating example where dark $SU(3)$ is spontaneously broken into $SU(2)$ subgroup by the ... More
Superconductivity In K- And Na- Doped Bafe2as2: What Can We Learn From Heat Capacity And Pressure Dependence of TcNov 24 2014A brief overview of changes in the superconducting transition temperature under pressure and evolution of specific heat capacity jump at Tc for two related families of iron - based superconductors, Ba{1-x}KxFe2As2 (0.2 < x < 1.0) and Ba{1-x}NaxFe2As2 ... More
Axion Haloscopes with Toroidal Geometry at CAPP/IBSSep 13 2016The present state of the art axion haloscope employs a cylindrical resonant cavity in a solenoidal field. We, the Center for Axion and Precision Physics Research (CAPP) of the Institute for Basic Science (IBS) in Korea, are also pursuing halo axion discovery ... More
On the problem of deformed spherical systems in Modified Newtonian DynamicsApr 20 2016Based on Newtonian dynamics, observations show that the luminous masses of astrophysical objects that are the size of a galaxy or larger are not enough to generate the measured motions which they supposedly determine. This is typically attributed to the ... More
The Gradient Expansion for the Free-Energy of a Clean SuperconductorSep 12 1998We describe a novel method for obtaining the gradient expansion for the free energy of a clean BCS superconductor. We present explicit results up to fourth order in the gradients of the order parameter.
Initial rigid response and softening transition of highly stretchable kirigami sheet materialsApr 23 2016May 03 2016We study, experimentally and theoretically, the mechanical response of sheet materials on which line cracks or cuts are arranged in a simple pattern. Such sheet materials, often called kirigami (the Japanese words, kiri and gami, stand for cut and paper, ... More
Interference effects of two scalar boson propagators on the LHC search for the singlet fermion DMOct 13 2016A gauge invariant UV-completion for singlet fermion DM interacting with the standard model (SM) particles involves a new singlet scalar. Therefore the model contains two scalar mediators, mixtures of the SM Higgs boson and a singlet scalar boson. Collider ... More
KU-ISPL Speaker Recognition Systems under Language mismatch condition for NIST 2016 Speaker Recognition EvaluationFeb 03 2017Feb 06 2017Korea University Intelligent Signal Processing Lab. (KU-ISPL) developed speaker recognition system for SRE16 fixed training condition. Data for evaluation trials are collected from outside North America, spoken in Tagalog and Cantonese while training ... More
The Algebraic Proof of the Universality TheoremFeb 03 2004In the long paper "Family Blowup formula, Admissible Graphs and the Enumeration of Singular Curves (I)" (appearing in JDG), the author solved the enumeration problem of nodal (or general singular) curve counting on algebraic surfaces by using techniques ... More
Delving into adversarial attacks on deep policiesMay 18 2017Adversarial examples have been shown to exist for a variety of deep learning architectures. Deep reinforcement learning has shown promising results on training agent policies directly on raw inputs such as image pixels. In this paper we present a novel ... More
Symplectic tomography of nonlinear coherent states of a trapped ionMar 03 2019Squeezed and rotated quadrature of an ion in a Paul trap is discussed in connection with reconstructing its quantum state using symplectic-tomography method. Marginal distributions of the quadrature for squeezed and correlated states and for nonlinear ... More
IceCube Events from Heavy DM decays through the Right-handed Neutrino PortalAug 11 2015Oct 21 2015The recently observed IceCube PeV events could be due to heavy dark matter (DM) decay. In this paper, we propose a simple DM model with extra $U(1)_X$ gauge symmetry and bridge it with standard model particles through heavy right-handed neutrino. The ... More
Self-interacting scalar dark matter with local $Z_{3}$ symmetryFeb 26 2014May 29 2014We construct a self-interacting scalar dark matter (DM) model with local discrete $Z_{3}$ symmetry that stabilizes a weak scale scalar dark matter $X$. The model assumes a hidden sector with a local $U(1)_X$ dark gauge symmetry, which is broken spontaneously ... More