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Jihn E. Kim

Publications and source records attributed to Jihn E. Kim.

At least 37 records · Page 2Linked to original sources
arXiv2020

Anticorrelation of Mass and Mixing Angle Hierarchies

We obtain a relationship between the hierarchies of mixing angles and of masses pertinent to the Cabibbo-Kobayashi-Maskawa (CKM) quark mixing matrix and the Pontecorvo-Maki-Nakagawa-Sakata (PMNS) lepton mixing matrix. Using this relationship, we argue that the more severe hierarchy of the charge-$\frac{2}{3}$ quark masses requires that the CKM matrix be close to a unit matrix whereas the milder hierarchy of the neutrino masses allows the PMNS matrix to depart markedly from the CKM matrix and contain large mixing angles of the type that are observed.

hep-ph↗
arXiv2020

Tetrahedral Symmetry A$_{\bf 4}$ in Anti-SU(5) GUT

We construct a flavor model in an anti-SU(5) GUT with a tetrahedral symmetry $A_4$. We choose a basis where $Q_{text{em}}=-\frac13$ quarks and charged leptons are already mass eigenstates. This choice is possible from the $A_4$ symmetry. Then, matter representation $\overline{10}_{-1}^{\rm\, matter}$ contains both a quark doublet and a heavy neutrino $N$, which enables us to use the $A_4$ symmetry to both $Q_{text{em}}=+\frac23$ quark masses and neutrino masses (through the see-saw via $N$). This is made possible because the anti-SU(5) breaking is achieved by the Higgs fields transforming as anti-symmetric representations of SU(5), $\overline{10}_{-1}^H\oplus 10_{+1}^H$, reducing the rank-5 anti-SU(5) group down to the rank-4 standard model group \smg. For possible mass matrices, the $A_4$ symmetry predictions on mass matrices at field theory level are derived. Finally, an illustration from string compactification is presented.

hep-ph↗
arXiv2020

Gauge hierarchy and SUSY: Think again

We revisit the gauge hierarchy problem with the emphasis on the chiral property of the Standard Model. We present a model realizing a gauge hierarchy. Along this line, we also comment briefly on the "very light" axions and the upper bound on $θ_{\rm QCD}$.

hep-ph↗
arXiv2019

Jarlskog determinant and data on flavor matrices

The essences of the weak CP violation, the quark and lepton Jarlskog invariants, are determined toward future model buildings beyond the Standard Model (SM). The equivalence of two calculations of Jarlskog invariants gives a bound on the CP phase in some parametrization. Satisfying the unitarity condition, we obtain the CKM and MNS matrices from the experimental data, and present the results in matrix forms. The Jarlskog determinant $J^q$ in the quark sector is found to be $\sim 3.11\times 10^{-5}|\sin\delks|$ while $J^\ell$ in the leptonic sector is $\sim 2.96\times 10^{-2}|\sin\delksl|$ in the normal hierarchy parametrization.

hep-ph↗
arXiv2019

Gauge Hierarchy

The chirality is the key for our world. In this scheme, I present a solution of the long standing gauge hierarchy problem with a hidden sector SU(5)$'$ with representations $\overline{\bf 10}\oplus \overline{\bf 5}\oplus 2\cdot{\bf 5}$. Sideway remarks are on {\it NATURAL HILLTOP} inflation and a bound on the QCD angle $\barθ$.

hep-ph↗
arXiv2019

History of Neutrino Magnetic Moment

In this historic Lomonosov conference on the occasion of 150 year anniversary of the Mendeleev's periodic table, I present the history of neutrino magnetic moment. It was first thought by Wolfgang Pauli and its magnitude was calculated during the gauge theory era.

hep-ph↗
arXiv2019

Axion Dark Matter Research with IBS/CAPP

The axion, a consequence of the PQ mechanism, has been considered as the most elegant solution to the strong-CP problem and a compelling candidate for cold dark matter. The Center for Axion and Precision Physics Research (CAPP) of the Institute for Basic Science (IBS) was established on 16 October 2013 with a main objective to launch state of the art axion experiments in South Korea. Relying on the haloscope technique, our strategy is to run several experiments in parallel to explore a wide range of axion masses with sensitivities better than the QCD axion models. We utilize not only the advanced technologies, such as high-field large-volume superconducting (SC) magnets, ultra low temperature dilution refrigerators, and nearly quantum-limited noise amplifiers, but also some unique features solely developed at the Center, including high-quality SC resonant cavities surviving high magnetic fields and efficient cavity geometries to reach high-frequency regions. Our goal is to probe axion dark matter in the frequency range of 1-10 GHz in the first phase and then ultimately up to 25 GHz, even in a scenario where axions constitute only 10% of the local dark matter halo. In this report, the current status and future prospects of the experiments and R&D activities at IBS/CAPP are described.

physics.ins-det↗
arXiv2019

A model of dynamical SUSY breaking

Supersymmetric (SUSY) models and dynamical breaking of symmetries have been used to explain hierarchies of mass scales. We find that a chiral representation, $\overline{\bf 10}\, \oplus\, \overline{\bf 5}\, \oplus\, 2\cdot{\bf 5}$ in SUSY SU(5) in the hidden sector, breaks global SUSY dynamically, by producing a composite field $ϕ$ below the SU(5) confinement scale. This dynamincal SUSY breaking can have two important applications, one in particle physics and the other in cosmology. Gavitational effects transmit this dynamical breaking to the standard model(SM) superpartners and the quintessential vacuum energy. The SM superpartners feel the effects just by the magnitude of the gravitino mass while the smallness of the quintessential vacuum energy is due to the composite nature of a singlet field $ϕ$. The composite $ϕ$ carries a global charge which is hardly broken in SUSY and hence its phase can be used toward a quintessential axion for dark energy of the Universe.

hep-th↗
arXiv2019

R-parity from string compactification

In this paper, we embed the $\Z_{4R}$ parity as a discrete subgroup of a global symmetry \UoR\,obtained from $\Z_{12-I}$ compactification of heterotic string $\EE8$. A part of \UoR\,transformation is the shift of the anticommuting variable $\vartheta$ to $e^{iα}\vartheta$ which necessarily incoorporate the transformation of internal space coordinate. Out of six internal spaces, we identify three U(1)'s whose charges are denoted as $Q_{18},Q_{20}$, and $Q_{22}$. The \UoR~is defined as \UEE$\times$\UKK~where \UEE~is the part from $\EE8$ and \UKK~is the part generated by $Q_{18},Q_{20}$, and $Q_{22}$. We propose a method to define a \UoR~direction. The needed vacuum expectation values for breaking gauge U(1)'s except U(1)$_Y$ of the standard model carry \UoR~charge 4 modulo 4 such that \UoR~is broken down to $\Z_{4R}$ at the grand unification scale. $\Z_{4R}$ is broken to $\Z_{2R}$ between the intermediate ($\sim 10^{11\,}\gev$) and the electroweak scales ($100\,\gev\sim 1\,\tev$). The conditions we impose are proton longevity, a large top quark mass, and acceptable magnitudes for the $μ$ term and neutrino masses.

hep-ph↗
arXiv2019

"Invisible" axion rolling through the QCD phase transition

The origin of `invisible' axion in four dimensional effective beyond-standard models from string compactification is discussed and its refined passover through the QCD phase transition is presented toward a reliable estimate of the current axion energy density in terms of the initial misalignment angle $\barθ_1$. The explicit examples are presented in a flipped SU(5) GUT model. This allows to introduce a flavor symmetry through string compactification, and hence we also comment on the source of flavor symmetries from string compactification and attempts to fit the resulting Yukawa couplings to the observed Cabibbo-Kobayashi-Maskawa and Pontecorvo-Maki-Nakagawa-Sakata matrices.

hep-ph↗
arXiv2019

Leptonic CP violation in flipped SU(5) GUT from $Z_{12-I}$ Orbifold Compactification

We obtain a phenomenologically acceptable PMNS matrix in a flipped SU(5) model inspired by the compactification of heterotic string $E_8\times E_8'$. To analyze the Jarlskog determinant efficiently, we include the simple Kim-Seo form for the Pontecorbo-Maki-Nakagawa-Sakata matrix. We also noted that $|δ_{\rm PMNS}|\lesssim 64^{\rm o}$ for the normal hierarchy of neutrino masses with the PDG book parametrization.

hep-ph↗
arXiv2018

Flavor mixing inspired by flipped SU(5) GUT

We obtain a phenomenologically acceptable Cabibbo-Kobayashi-Maskawa matrix in a flipped SU(5) model inspired by the compactification of heterotic string $E_8\times E_8'$.

hep-ph↗
arXiv2018

"Invisible" QCD axion rolling through the QCD phase transition

Visible matter in the current Universe is a consequence of the phase transition of the strong force, quantum chromodynamics (QCD). This phase transition has occurred at the Universe temperature around $T_c\simeq 165\,$MeV while it was expanding. Strongly interacting matter particles are quarks above $T_c$, while they are pions, protons and neutrons below $T_c$. The spin degrees of freedom 37 in the quark and gluon phase just above $T_c$ are converted to 3 (pions) after the phase transition. This phase transition might have been achieved mostly at supercooled temperatures. The supercooling was provided by the expansion of the Universe. We obtain the effective bubble formation rate $α(T)\approx 10^{4-5}\,$MeV and the completion temperature of the phase change (to the hadronic phase), $T_f\simeq 126\,$MeV. During the phase transition, the scale factor $R$ has increased by a factor of 2.4. This provides a key knowledge on the energy density of "invisible" QCD axion at the full hadronic-phase commencement temperature $T_f$, and allows for us to estimate the current energy density of cold dark matter composed of "invisible" QCD axions.

hep-ph↗
arXiv2018

Theory of flavors: String compactification

We present a calculating method for the quark and lepton mixing angles. After a general discussion in field theoretic models, we present a working model from a string compactification through $Z_{12-I}$ orbifold compactification. It is beyond presenting just three families of the standard model but is the first example from string compactification successfully fitting to the observed data. Assuming that all Yukawa couplings from string compactification are real, we also comment on a relation between the CP phases in the Jarlskog determinants obtained from the CKM and PMNS matrices. The flipped SU(5) model leads to the doublet-triplet splitting and possible proton decay operators. It is shown that the vacuum expectation values can be tuned such that the proton lifetime is long enough.

hep-ph↗
arXiv2018

Axion energy density, bottle neck period, and $\barθ$ ratios between early and late times

The possibility of the "invisible" axion being cold dark matter relies on the acceptable estimates of the current axion energy density. The estimate depends on the nature of QCD phase transition at a few hundred MeV and the evolution of the misalignment angle $\barθ$. The onset of $\barθ$ oscillation undergoes a bottleneck period which occurred during the QCD phase transition. In addition, the anharmonic coupling of order $a^4$ affects the $\barθ$ evolution. From the time that the anharmonic effect is negligible, it is rather simple to calculate the ratio of $\barθ$'s between early and late times. For multi GHz oscillations, the current age of the Universe needs at least $10^{27}$ oscillations which limits an exact calculation of $\barθ$ . We establish a stepwise approximation for numerical solutions of the differential equation and obtain $\barθ_{\rm now}/\barθ_f\approx 3\times 10^{-17}$ for $m_a\simeq 10^{-4}\,$eV, where $t_f$ is the first time that the full hadronic phase (after the QCD phase transition) was established.

hep-ph↗
arXiv2018

Fate of global symmetries in the Universe: QCD axion, quintessential axion and trans-Planckian inflaton decay-constant

Pseudoscalars appearing in particle physics are reviewd systematically. From the fundamental point of view at an ultra-violat completed theory, they can be light if they are realized as pseudo-Goldstone bosons of some spontaneously broken global symmetries. The spontaneous breaking scale is parametrized by the decay constant $f$. The global symmetry is defined by the lowest order terms allowed in the effective theory consistent with the gauge symmetry in question. Since any global symmetry is known to be broken at least by quantum gravitational effects, all pseudoscalars should be massive. The mass scale is determined by $f$ and the explicit breaking terms $ΔV$ in the effective potential and also anomaly terms $ΔΛ^4_G$ for some non-Abelian gauge groups $G$. The well-known example by non-Abelian gauge group breaking is the potential for the "invisible" QCD axion, via the Peccei-Quinn symmetry, which constitutes a major part of this review. Even if there is no breaking terms from gauge anomalies, there can be explicit breaking terms $ΔV$ in the potential in which case the leading term suppressed by $f$ determines the pseudoscalar mass scale. If the breaking term is extremely small and the decay constant is trans-Planckian, the corresponding pseudoscalar can be a candidate for a `quintessential axion'. In general, $(ΔV)^{1/4}$ is considered to be smaller than $f$, and hence the pseudo-Goldstone boson mass scales are considered to be smaller than the decay constants. In such a case, the potential of the pseudo-Goldstone boson at the grand unification scale is sufficiently flat near the top of the potential that it can be a good candidate for an inflationary model, which is known as `natural inflation'. We review all these ideas in the bosonic collective motion framework.

hep-ph↗
arXiv2018

Concept of multiple-cell cavity for axion dark matter search

In cavity-based axion dark matter search experiments exploring high mass regions, multiple-cavity design is considered to increase the detection volume within a given magnet bore. We introduce a new idea, referred to as multiple-cell cavity, which provides various benefits including a larger detection volume, simpler experimental setup, and easier phase-matching mechanism. We present the characteristics of this concept and demonstrate the experimental feasibility with an example of a double-cell cavity.

astro-ph.IM↗