arXiv subjects

Ji-Haeng Huh

Publications and source records attributed to Ji-Haeng Huh.

27 records · Page 2Linked to original sources

arXiv2009

Decaying dark matter with heavy axino

A TeV scale decaying dark matter chiral multiplet N is introduced in addition to the minimal supersymmetric standard model(MSSM). For a calculable abundance of N, we introduce heavy axino decaying to N and MSSM particles including the lightest supersymmetric particle(LSP). In the scenario that heavy axino, once dominating the energy density of the universe, decays after the LSP decouples, it is possible to estimate the relative cosmic abundances of N and the LSP. Dimension 6 interactions allow the lifetime of the fermionic or the bosonic superpartner of N in the 10^{27} s range to be compatible with the recent astrophysical bounds. A diagrammatic strategy obtaining a suppression factor 1/M^2 is also given.

hep-ph↗

arXiv2009

SU(5)_{flip} x SU(5)' from Z_{12-I}

Based on the Z_{12-I} orbifold compactification of the heterotic string theory, we construct a flipped-SU(5) model with three families of the standard model matter and ingredients for dynamical supersymmetry breaking. The doublet-triplet splittings in the Higgs representations 5_{-2} and \bar{5}_{2} are achieved by the couplings 10_{1}10_{1}5_{-2} and \bar{10}_{-1}\bar{10}_{-1}\bar{5}_{2}, where 10_{1} and \bar{10}_{-1} develop GUT scale vacuum expectation values, breaking the flipped-SU(5) down to the standard model gauge group. In this model, all the exotic states are decoupled from the low energy physics, and sin^2θ_W^0=3/8. Above the compactification scale, the flipped-SU(5) gauge symmetry is enhanced to the SO(10) gauge symmetry by including the Kaluza-Klein (KK) modes. The hidden sector gauge group is SU(5)'. The threshold correction by the KK modes allow a very wide range for the hidden sector confining scale (10^{11} GeV -- 10^{16} GeV). One family of hidden matter (\bar{10}' and 5') gives rise to dynamical supersymmetry breaking.

hep-ph↗

arXiv2009

The minimal two DM components with SUSY

We present the dark matter extension of the minimal supersymmetric standard model by one more two component stable fermion N toward explaining the recent rising high energy positron spectrum of the PAMELA data. The needed coupling can arise in the flipped-SU(5) GUT.

hep-ph↗

arXiv2009

White dwarf axions, PAMELA data, and flipped-SU(5)

Recently, there are two hints arising from physics beyond the standard model. One is a possible energy loss mechanism due to emission of very weakly interacting light particles from white dwarf stars, with a coupling strength ~ 0.7x10^{-13}, and another is the high energy positrons observed by the PAMELA satellite experiment. We construct a supersymmetric flipped-SU(5) model, SU(5)xU(1)_X with appropriate additional symmetries, [U(1)_H]_{gauge}x[U(1)_RxU(1)_Γ]_{global}xZ_2, such that these are explained by a very light electrophilic axion of mass 0.5 meV from the spontaneously broken U(1)_Γand two component cold dark matters from Z_2 parity. We show that in the flipped-SU(5) there exists a basic mechanism for allowing excess positrons through the charged SU(2) singlet leptons, but not allowing anti-proton excess due to the absence of the SU(2) singlet quarks. We show the discovery potential of the charged SU(2) singlet E at the LHC experiments by observing the electron and positron spectrum. With these symmetries, we also comment on the mass hierarchy between the top and bottom quarks.

hep-ph↗

arXiv2009

Two dark matter components in N_{DM}MSSM and dark matter extension of the minimal supersymmetric standard model and the high energy positron spectrum in PAMELA/HEAT data

We present the dark matter (DM) extension (by N) of the minimal supersymmetric standard model to give the recent trend of the high energy positron spectrum of the PAMELA/HEAT experiments. If the trend survives by future experiments, the MSSM needs to be extended. Here, we minimally extend the MSSM with one more DM component N together with a heavy lepton E, and introduce the coupling e_R E_R^c N_R. This coupling naturally appears in the flipped SU(5) GUT models. This N_{DM}MSSM contains the discrete symmetry Z_6, and for some parameter ranges there result two DM components. For the MSSM fields, the conventional R-parity, which is a subgroup of Z_6, is preserved. We also present the needed parameter ranges of these additional particles.

hep-ph↗

arXiv2008

Updated Axion CDM energy density

We update cosmological bound on axion model. The contribution from the anharmonic effect and the newly introduced initial overshoot correction are considered. We present an explicit formula for the axion relic density in terms of the QCD scale Lambda_{QCD}, the current quark masses m_q's and the Peccei-Quinn scale F_a, including firstly introduced 1.85 factor which is from the initial overshoot.

hep-ph↗

arXiv2008

511 keV $γ$-ray emission from the galactic bulge by MeV millicharged dark matter

We propose a possible explanation for the recently observed anomalous 511 keV line with a new "millicharged" fermion. This new fermion is light [${\cal O}({\rm MeV})$]. Nevertheless, it has never been observed by any collider experiments by virtue of its tiny electromagnetic charge $εe$. In particular, we constrain parameters of this millicharged particle if the 511 keV cosmic $γ$-ray emission from the galactic bulge is due to positron production from this new particle.

hep-ph↗

arXiv2008

Update of axion CDM energy density

We improve the estimate of the axion CDM energy density by considering the new values of current quark masses, the QCD phase transition effect and a possible anharmonic effect.

hep-ph↗

arXiv2008

Galactic 511 keV line from MeV millicharged dark matter

We present a possible explanation of the recently observed 511 keV $γ$-ray anomaly with a new ``millicharged'' fermion. The new fermion is light (${\cal O}({\rm MeV})$) but has never been observed by any collider experiments mainly because of its tiny electromagnetic charge $εe$. We show that constraints from its relic density in the Universe and collider experiments allow a parameter range such that the 511 keV cosmic $γ$-ray emission from the galactic bulge may be due to positron production from this millicharged fermion.

astro-ph↗