Lifetime Limit of LSP from Cosmological Light Elements
From the present cosmic abundance of the light elements, one can obtain a lifetime bounds of LSP. From the consideration of deuterium, we obtain $τ_χ \ge 10^6$ s.
astro-ph↗
arXiv subjects
Jihn E. Kim
Publications and source records attributed to Jihn E. Kim.
A natural solution of $μ$ from the hidden sector
The $μ$ parameter is calculated in supergravity models possessing the $U(1)_A\times U(1)_R$ symmetry. In one natural model without a free mass parameter below the Planck scale, the symmetry breaking scale is identified as the hidden sector squark condensation scale.
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Axion and Almost Massless Quark as Ingredients of Quintessence
It is pointed out that a natural introduction of quintessence is an axion with an almost massless quark. With an appropriate gauge or discrete symmetry, one can obtain the quintessence potential height of order $(0.003 eV)^4$. Even though the QCD axion with almost massless up quark is a possibility, we stress the almost massless quark in the hidden sector together with the QCD axion toward the quintessence.
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Bounds and Implications of Neutrino Magnetic Moments from Atmospheric Neutrino Data
The neutral current effects of the future high statistics atmospheric neutrino data can be used to distinguish the mechanisms between a $ν_μ$ oscillation to a tau neutrino or to a sterile neutrino. However, if neutrinos possess large diagonal and/or transition magnetic moments, the neutrino magnetic moments can contribute to the neutral current effects which can be studied by the single $π^0$ production events in the Super-K data. This effect should be included in the future analyses of atmospheric data in the determination of $ν_μ$ to tau or sterile neutrino oscillation.
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Axion Theory Review
I review the axion physics with emphases on the couplings of the very light axion and a possible realization in superstring models.
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R_F Parity and Almost Massless Up Quark
We introduce a parity $R_F$ to introduce naturally small masses for the first family members and in particular almost massless $u$ quark toward the strong CP solution. We also discuss the phenomenological implications of this model on the proton decay and the neutrino mass. Furthermore, it is possible to embed this $R_F$ parity to local $U(1)_R$ gauge symmetry.
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Large Cosmological Light Element Bound on R Parity Violating Parameters
In R parity violating theories, there does not exist the {\it stable} lightest supersymmetric particle (LSP). The LSP, $χ$, of MSSM decays to lighter ordinary particles with dimension 6 effective R violating interaction terms. Since the lifetime of $χ$ can be sufficiently long for small R-violating couplings, it can affect the standard nucleosynthesis scenario. This constraint gives an upper limit for the lifetime of $χ$ in the small $τ_χ$ region; $\simτ_χ>10^6$ s. This translates to the sum of squared R-violating couplings, for $m_χ=$ 60 GeV in the photino (bino) limit, $(0.12 (0.05)|λ_{i,j,k}|^2+0.31(0.07) |λ^\prime_{i,j\ne 3,k}|^2 +0.04(0.04)|λ^{\prime}_{i,3,k}|^2 +0.23(0.12)|λ_{i,j,k}^{\prime\prime}(i 7.7\times 10^{-24}$.
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Mass Matrix Ansatz for Degenerate Neutrinos Consistent with Solar and Atmospheric neutrino Data
We suggest mass matrices for neutrinos and charged leptons that can explain solar and atmospheric neutrino data. The resulting flavor mixing matrix $V_ν$ has a property that $(V_ν)_{13}=0$, thus making $ν_e \leftrightarrow ν_μ$ and $ν_μ \leftrightarrow ν_τ$ oscillations to be effectively a two-channel problem. Phenomenological consequences of the lepton mass matrix ansatze are consistent with the current data on various type of neutrino oscillation experiments except the LSND measurement. %and that three neutrinos are almost degenerate in mass. Three neutrinos, being almost degenerate with $\sum | m_{ν_i} | \lesssim 1 $ eV, can be a part of hot dark matter without any conflict with the constraint from neutrinoless double beta decay experiments. The $ν_μ \leftrightarrow ν_τ$ oscillation, $\sin^2{2θ_{μτ}}$, is predicted to be 0.86-0.97 with $Δm^2_{μτ}\simeq 2 \times 10^{-3} {eV}^2$, which is consistent with the atmospheric neutrino data and can be tested further at the planned MINOS and K2K experiments searching for $ν_μ \to ν_τ$ oscillation.
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Superstring Axion, Gaugino Condensation, and Discrete Symmetries
Here I present the effect of gaugino condensation and discrete symmetries to the model-independent axion potential, collaborated with Georgi and Nilles [hep-ph/9805510].
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Hidden Sector Gaugino Condensation and the Model-independent Axion
In the effective field theory framework, we consider the effect of supersymmetry breaking via gaugino condensation and supergravity in the hidden sector gauge group on the hidden sector vacuum angle $θ_h$. The $θ_h$ parameter dependence of the potential yields phenomenologically acceptable invisible axion solutions if the $U(1)_R$ symmetry is broken down to a discrete subgroup $Z_N$ with $N\ge 3$ (N=4 is marginal). Anomalous U(1) superstring models are good candidates for this invisible axion resolution of the strong CP puzzle.
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Cosmic Axion
I review the axionic solution of the strong CP problem and current status of the cosmic axion search.
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Constraints on Very Light Axions from Cavity Experiments
In view of the ongoing galactic (or cosmic) axion detection experiments, we compare the axion-photon-photon coupling $c_{aγγ}$'s for various invisible (or very light) axion models.
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Global Symmetries in Duals of Supersymmetric SU(N) x SU(M) and Application to Composite Axion
In this paper, we construct a supersymmetric composite axion (c-axion) model based on the gauge group $SU(N)\times SU(M)$, which is one possible physical application of the N=1 duality. The dual of SU(M) is interpreted as the color gauge group. We illustrate the existence of c-axion for the case of one dual quark in the dual gauge group $SU(\tilde M)$.
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Supersymmetric interpretation of high--$Q^2$ HERA events and other related issues
In the framework of the minimal supersymmetric standard model (MSSM) with $R-$parity violation, the high--$Q^2$ HERA events can be interpreted as the $s-$channel production of a single stop of $M_{\tilde{t}_1} \approx 200$ GeV, whose dominant decay modes are assumed to be the $R-$parity violating $e^+ + d $ and the $R-$parity conserving $χ^+ + b$. Assuming only one coupling $\bar{λ_{131}^{'}}$ is nonzero of order $\sim 0.04-0.12$, we find that (i) the high$-Q^2$ HERA events can be understood as an $s-$channel stop production with a subsequent decay into $e^+ + (single ~jet)$, and (ii) the ALEPH 4-jet events can be understood in the scenario suggested by Carena et al.. We briefly discuss other physics signals of this scenario at other places such as HERA, LEP200 and Tevatron. The best test for our scenario is to observe the stop decay into $χ^+ + b$ followed by $χ^+ \to \tilde{e}^+ + ν_e $ and $\tilde{e}^+ \to q + \bar{q}^{'}$ via the $R-$parity violating coupling.
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The Axino-Gravitino Cosmology
A cosmological scenario of a light axino and a lighter gravitino is presented. The most important consequence is that it can mimick the mixed dark matter (MDM) model of the large scale structure formation. The presence of axino and gravitino is inevitable in supergravity extension of the invisible axion solution of the strong CP problem. The possibility of a light gravitino is popular in the recent efforts of gauge mediated supersymmetry breaking.
astro-ph↗
More on R-parity and lepton-family number violating couplings from muon(ium) conversion, and τand $π^0$ decays
We present a new class of constraints to the lepton-family number and R-parity violating couplings from muonium conversion, $μ^{-} + {_{22}^{48}} Ti \to e^{-} + {_{22}^{48}} Ti$, a class of tau decays, $τ\to l +$ (light meson) with $l= μor e$, and $J/ψ$ and $π^0$ decays into a lepton pair. We find that $μ^{-} + {_{22}^{48}} Ti \to e^- + {_{22}^{48}} Ti$ provides one of the strongest constraints along with $Δm_{K}, Δm_{B}$, $μ\to e γ$ and the neutrinoless double $β$ decay. Search for these lepton-family number violating (LFNV) decays forbidden in the standard model is clearly warranted in various low-energy experiments such as Tau-Charm Factories and PSI, etc.
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Almost maximally broken permutation symmetry for neutrino mass matrix
Assuming 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 fixed by measured charged lepton masses, differences of squared neutrino masses relevant to the solar and the atmospheric neutrino puzzles, and the masses of three light Majorana neutrinos as a candidate for hot dark matter with $\sum |m_ν| \sim 6 eV$. The resulting neutrino mixing is compatible with the data for the current upper limit, $ < m_{ν_e} >_{th} < 0.8 eV$, of neutrino-less double beta decay experiments, and the current data for various types of neutrino oscillation experiments. One solution of our model predicts that $ν_μ \rightarrow ν_τ$ oscillation probability is about $< 0.008$ with $Δm^{2} \sim 10^{-2} eV^2$, which may not be accessible at CHORUS and other ongoing experiments.
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