arXiv subjects

Jae Sik Lee

Publications and source records attributed to Jae Sik Lee.

At least 91 records · Page 5Linked to original sources

arXiv2001

CP Violation in Tau Slepton Pair Production at Muon Colliders

We discuss in detail signals for CP violation in the Higgs boson and tau-slepton sectors through the production processes $μ^+μ^- \to \tildeτ_i^- \tildeτ_j^+$, where $i,j=1,2$ label the two $τ$ slepton mass eigenstates in the minimal supersymmetric standard model. We assume that the soft breaking parameters of third generation sfermions contain CP violating phases, which induce CP violation in the Higgs sector through quantum corrections. We classify all the observables for probing CP violation in the Higgs boson and $τ$ slepton sectors. These observables depend on the initial muon beam polarization, where we include transverse polarization states. If the heavy Higgs bosons can decay into tau slepton pairs, a complete determination of the CP properties of the neutral Higgs boson and $τ$--slepton systems is possible. The interference between the Higgs boson and gauge boson contributions could also provide a powerful method for probing CP violation, if transversely polarized muon beams are available. We show in detail how to directly measure CP violation in the tau slepton system, under the assumption that the neutral Higgs mixing angles are determined through the on--shell production of the neutral Higgs bosons.

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arXiv2001

Probing MSSM Higgs Sector CP Violation at a Photon Collider

We study the phenomenological implications of the Higgs sector CP violation at a photon collider. In our model, the CP violation is radiatively induced by the non-trivial CP phases of the third-generation scalar-quark sector in the MSSM. We re-evaluate the $s$-channel resonance production cross sections and the polarization asymmetries of the neutral Higgs bosons based on the calculation of the mass matrix of the neutral Higgs bosons which is valid for any values of the relevant SUSY parameters. The CP properties of the Higgs bosons can be precisely probed through their $s$-channel resonance productions at a photon linear collider by exploiting circularly and/or linearly polarized backscattered laser photons.

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arXiv2001

Higgs Boson Decays in the Minimal Supersymmetric Standard Model with Radiative Higgs Sector CP Violation

We re-evaluate the decays of the Higgs bosons in the minimal supersymmetric standard model (MSSM) where the tree-level CP invariance of the Higgs potential is explicitly broken by the loop effects of the third-generation squarks with CP-violating soft-breaking Yukawa interactions. This study is based on the mass matrix of the neutral Higgs bosons that is valid for arbitrary values of all the relevant MSSM parameters. It extends the previous work considerably by including neutral Higgs-boson decays into virtual gauge bosons and those into top-squark pairs, by implementing squark-loop contributions to the two-gluon decay channel, and by incorporating the decays of the charged Higgs boson. The constraints from the electron electric dipole moment on the CP phases are also discussed. We find that the branching fractions of both the neutral and charged Higgs-boson decays and their total decay widths depend strongly on the CP phases of the top (and bottom) squark sectors through the loop-induced neutral Higgs boson mixing as well as the direct couplings of the neutral Higgs bosons to top squark pairs.

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arXiv2000

Probing the MSSM Higgs Boson Sector with Explicit CP Violation through Third Generation Fermion Pair Production at Muon Colliders

We perform a systematic study of the production of a third-generation fermion-pair, $μ^+μ^-\to f\bar{f}$ for $f=τ^-,b$, and t in the minimal supersymmetric standard model (MSSM) with explicit CP violation, which is induced radiatively by soft trilinear interactions related to squarks of the third generation. We classify all the observables for probing the CP property of the Higgs bosons constructed by the initial muon beam polarization along with the unpolarized final fermions and with the final-fermion polarization configuration of equal helicity, respectively. The observables allow for complete determination of CP property of the neutral Higgs bosons. The interference between the Higgs boson and gauge boson contributions also could provide a powerful method for the determination of the CP property of two heavy Higgs bosons in the top-quark pair production near the energy region of the Higgs-boson resonances. For the lightest Higgs-boson mass there is no sizable interference between scalar and vector contributions for the determination of the CP property of the lightest Higgs boson. We give a detailed numerical analysis to show how the radiatively-induced CP violation in the Higgs sector of the MSSM can be measured.

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arXiv2000

CP Asymmetries in Radiative B Decays with R-parity Violation

We analyze the effect of R-parity violation in the minimal supersymmetric standard model on the CP asymmetries in $b\to s γ$ decay. The direct and mixing-induced CP asymmetries arising from the lepton number violating couplings are strongly constrained by the current experimental limits on the corresponding couplings. Allowing a heavy neutrino ($m_{ν_τ}\sim10$ keV) and a moderate mass splitting of sfermions, the direct CP asymmetry around 15 % and the nearly maximal mixing-induced CP asymmetry ($\sim 100 %$) can be realized, depending on the R-parity conserving contributions to the radiative $b$ decay. With the baryon number violating couplings, only the mixing-induced CP asymmetry arises and it can be maximal provided there is a the similar sfermion mass splitting.

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arXiv2000

Measuring the Higgs CP Property through Top Quark Pair Production at Photon Linear Colliders

We present a model-independent study of the effects of a neutral Higgs boson without definite CP-parity in the process $γγ\to t\bar{t}$ around the mass pole of the Higgs boson. Near the resonance pole, the interference between the Higgs-exchange and the continuum amplitudes can be sizable if the photon beams are polarized and helicities of the top and anti-top quarks are measured. Study of these interference effects enables one to determine the CP property of the Higgs boson completely. An example of the complete determination is demonstrated in the context of the minimal supersymmetric standard model.

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arXiv2000

Loop Corrections to the Neutral Higgs Boson Sector of the MSSM with Explicit CP Violation

We compute one-loop corrections to the mass matrix of the neutral Higgs bosons of the Minimal Supersymmetric Standard Model with explicit CP violation. We use the effective potential method, allowing for arbitrary splitting between squark masses. We include terms O(g^2 h^2), where g and h stand for electroweak gauge and Yukawa couplings, respectively. Leading two-loop corrections are taken into account by means of appropriately defined running quark masses.

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arXiv2000

s-Channel Production of MSSM Higgs Bosons at a Muon Collider with Explicit CP Violation

A muon collider with controllable energy resolution and transverse beam polarization provides a powerful probe of the Higgs sector in the minimal supersymmetric standard model with explicit CP violation, through s-channel production of Higgs bosons. The production rates and the CP-even and CP-odd transverse-polarization asymmetries are complementary in diagnosing CP violation in the Higgs sector.

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arXiv2000

Probing MSSM Higgs Sector with Explicit CP Violation at a Photon Linear Collider

The CP properties of Higgs bosons can be probed through their s-channel resonance productions via photon-photon collisions by use of circularly and/or linearly polarized backscattered laser photons at a TeV-scale linear e^+ e^- collider. Exploiting this powerful tool, we investigate in detail the Higgs sector of the minimal supersymmetric Standard Model with explicit CP violation.

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arXiv1999

MSSM Higgs-Boson Production at Hadron Colliders with Explicit CP Violation

Gluon fusion is the main production mechanism for Higgs bosons with masses up to several hundred GeV in $pp$ collisions at the CERN Large Hadron Collider. We investigate the effects of the CP-violating phases on the fusion process including both the sfermion-loop contributions and the one-loop induced CP-violating scalar-pseudoscalar mixing in the minimal supersymmetric standard model. With a universal trilinear parameter assumed, every physical observable involves only the sum of the phases of the universal trilinear parameter $A$ and the higgsino mass parameter $μ$. The phase affects the lightest Higgs-boson production rate significantly through the neutral Higgs-boson mixing and, for the masses around the lightest stop-pair threshold, it also changes the production rate of the heavy Higgs bosons significantly through both the stop and sbottom loops and the neutral Higgs-boson mixing.

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arXiv1999

Constraints on Parameters of the R_F Parity Model from Quark and Neutrino Mass Matrices

The forms of quark and lepton mass matrices are severely restricted in the $R_F$ parity model. We determine the form of the quark mass matrix first and derive the form of the neutrino mass matrix. For this to be consistent with the present experiments, we conclude that the masses of the superpartners of the right--handed down-type squarks and sneutrino vacuum expectation values satisfy, ${m_{\tilde{d}_{Rj}}}\vmu \gtrsim 400 ~{\rm GeV}^2 $ or ${m_{\tilde{d}_{Rj}}}\vtau \gtrsim 400 ~{\rm GeV}^2 $. We also find that without a sterile neutrino it is difficult to obtain a large mixing angle solution of $ν_μ$ and $ν_τ$. With a sterile neutrino, we show a possibility for a large mixing angle solution of $ν_μ$ with $ν_{\rm sterile}$.

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arXiv1999

Decays of the MSSM Higgs Bosons with Explicit CP Violation

We study Higgs boson decays in the minimal supersymmetric standard model where the tree-level CP invariance of the Higgs potential is explicitly broken by loop effects of soft CP-violating Yukawa interactions related to scalar quarks of the third generation. The scalar-pseudoscalar mixing among two neutral CP-even Higgs bosons and one CP-odd Higgs boson due to explicit CP violation modifies their tree-level couplings to fermions, to the W^\pm and Z bosons and to Higgs bosons themselves significantly. We analyze the phenomenological impact of explicit CP violation on the branching ratios of the neutral Higgs boson decays in detail and discuss how to directly confirm the existence of explicit CP violation through τ^+ τ^- and t \bar{t} spin correlations in the decays of the neutral Higgs bosons into a tau-lepton pair and a top-quark pair.

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arXiv1999

Neutrino Mass and Lepton Number Violation with Charged Scalars

If there exist only three light neutrinos below the weak scale, the neutrino masses can arise by breaking the lepton number L. One example is the Zee mechanism for the neutrino masses. We study phenomenological implications of neutrino masses arising from the L violation through introduction of SU(2) X U(1) singlet scalars with Q_{em}=1 and 2.

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arXiv1999

Neutrino Oscillations and R-parity Violating Collider Signals

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 observing decay products of the destabilized LSP. We examine all the possible decay processes of the neutralino LSP assuming the bilinear contribution to neutrino masses dominates over the trilinear one which gives rise to the solar neutrino mass. We find that it is possible to probe neutrino oscillations through colliders in most of the R-parity conserving MSSM parameter space.

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arXiv1999

Implication of Super-Kamiokande Data on R-parity Violation

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 (charginos) and neutrinos (charged leptons) driven by the bilinear terms take factorized forms, which may enable us to probe the neutrino mixing parameters in a collider. It is then shown that the Super-Kamiokande data on atmospheric neutrinos require all the baryon number violating couplings to be substantially suppressed: $λ''_{\rm any} <10^{-9}$.

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arXiv1999

CP Violating B Decays with R-parity Violation

We study CP violating B decays in the minimal supersymmetric standard model with R-parity violation. We estimate how much R-parity violation modifies the SM predictions for CP asymmetries in B decays within the present bounds. The effects of R-parity- and lepton-number-violating couplings on the ratio of the decay amplitude due to R-parity violation to that of the SM can differ by one or two orders of magnitudes depending on the models of the left-handed quark mixing. It is possible to disentangle the R-parity violating effects from those of the SM and R-parity- conserving supersymmetric models within the present bounds comparing different CP violating decay amplitudes. We also study the effects of R-parity- and baryon-number-violating couplings and find that the effects could be large.

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arXiv1999

Possible New Physics Signals in b -> s gamma and b -> s l^+ l^-

We consider possible new physics contributions to b\to s l^+ l^- assuming the new physics modifies (chromo)magnetic and electric form factors in b\to s γ^* and b\to s g with the same chirality structure as in the standard model. Parametrizing the new physics effects on b\to s γ^* and b\to s g in terms of four real parameters, one finds that there are enough region of parameter space in which the measured branching ratio for B \to X_s γcan be accomodated, and the predicted CP violation effect could be as large as \sim 30%. Moreover, the branching ratio and the forward-backward asymmetry of a lepton in B \to X_s l^+ l^- and the tau polarization asymmetry in B \to X_s τ^+ τ^- can be deviated from the SM predictions by a factor of \sim 2, which can be accessible at B factories. We also discuss these observables in a specific class of supersymmetric models with gluino-mediated flavor changing neutral current (FCNC).

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arXiv1999

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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