LHC Signatures of MSSM Higgs-sector CP Violation
We discuss a few new characteristic features of the loop-induced MSSM Higgs-sector CP violation at the LHC based on two scenarios: (i) CPX and (ii) Trimixing.
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arXiv subjects
Jae Sik Lee
Publications and source records attributed to Jae Sik Lee.
Probing Higgs-sector CP Violation at a Photon Collider
In this review we demonstrate physics potential of a photon linear collider by studying the neutral Higgs-boson sector of the MSSM in which interesting CP-violating Higgs mixing could arise via radiative corrections.
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Lightest Higgs Boson and Relic Neutralino in the MSSM with CP Violation
We discuss the lower bound to the lightest Higgs boson H_1 in the minimal supersymmetric extension of the standard model (MSSM) with explicit CP violation, and the phenomenology of the lightest relic neutralino in the same scenario. In particular, adopting the CPX benchmark scenario, we find that the combination of experimental constraints coming from LEP, Thallium Electric Dipole Moment (EDM) measurements, quorkonium decays, and B_s -> mu mu decay favours a region of the parameter space where the mass of H_1 is in the range 7 GeV < M_{H_1} < 10 GeV, while 3 < tan(beta) < 5. Assuming a departure from the usual GUT relation among gaugino masses (|M_1| << |M_2|), we find that through resonant annihilation to H_1 a neutralino as light as 2.9 GeV can be a viable dark matter candidate in this scenario. We call this the CPX light neutralino scenario, and discuss its phenomenology showing that indirect Dark Matter searches are compatible with the present experimental constraints, as long as m_χ< M_{H_1}/2. On the other hand, part of the range m_χ> M_{H_1}/2 which is allowed by cosmology is excluded by antiproton fluxes.
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Higgs Phenomenology with CPsuperH
The MSSM contains CP-violating phases that may have important observable effects in Higgs physics. We review recent highlights in Higgs phenomenology obtained with the code CPsuperH, a useful tool for studies of the production, mixing and decay of a coupled system of the neutral Higgs bosons at future high energy colliders such as the LHC, ILC ($γ$LC), and a muon collider (MC). CPsuperH implements the constraints from upper limits on electric dipole moments, and may be extended to include other related low-energy observables, such as b -> s γand B -> K l l, and to compute the relic abundance of the lightest neutralino.
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Addendum to ``Threshold corrections to $m_b$ and the $\bar{b}b \to H^0_i$ production in CP-violating SUSY scenarios''
In hep-ph/0401024: ``Threshold corrections to $m_b$ and the $\bar{b}b\to H^0_i$ production in CP-violating SUSY scenarios'', we have pointed out that the production cross sections of the three neutral Higgs bosons through $\bar{b}b$ fusion can deviate substantially from those obtained in CP conserving scenarios, thanks to the nontrivial role played by the threshold corrections to $m_b$ combined with the CP-violating mixing in the neutral-Higgs-boson sector. The deviations are largest for values of the CP-violating phases that maximize the mixing among at least two of the three neutral Higgs bosons. We complement our previous work focussing explicitly on the values of masses and widths of the three neutral Higgs bosons in this region of parameter space. We then address the issue of whether the three different peaks in the invariant mass distribution of the Higgs-decay products can be experimentally disentangled at the LHC.
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Resonant CP Violation in Higgs Radiation at e^+e^- Linear Collider
We study resonant CP violation in the Higgsstrahlung process e^+e^- -> H_{1,2,3} (Z -> e^+e^-, μ^+μ^-) and subsequent decays H_{1,2,3} -> b \bar{b}, τ^-τ^+, in the MSSM with Higgs-sector CP violation induced by radiative corrections. At a high-energy e^+e^- linear collider, the recoil-mass method enables one to determine the invariant mass of a fermion pair produced by Higgs decays with a precision as good as 1 GeV. Assuming an integrated luminosity of 100/fb, we show that the production lineshape of a coupled system of neutral Higgs bosons decaying into b\bar{b} quarks is sensitive to the CP-violating parameters. When the Higgs bosons decay into τ^-τ^+, two CP asymmetries can be defined using the longitudinal and transverse polarizations of the tau leptons. Taking into account the constraints from electric dipole moments, we find that these CP asymmetries can be as large as 80 %, in a tri-mixing scenario where all three neutral Higgs states of the MSSM are nearly degenerate and mix significantly.
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Heavy Majorana Neutrino Production at e- gamma Colliders
We study signatures of heavy Majorana neutrinos at e- gamma colliders. Since these particles violate lepton number, they can give rise to the reactions e- gamma -> W- W- e+ and e- gamma -> W+ mu- mu- nu. The Standard Model background contains extra light neutrinos that escape detection, and can be reduced significantly after imposing appropriate kinematical cuts. We analyze the physics potential of an e- gamma collider, with centre of mass energies sqrt(s) = 0.5--1 TeV and a total integrated luminosity of 100/fb, for detecting heavy Majorana neutrinos with masses mN = 100--400 GeV. Assuming that heavy neutrinos couple predominantly to one lepton flavour at a time, we find that 10 expected background-free events can be established for |B_{eN}| >~ 4.6 x 10^{-3}. Instead, if no signal is observed, this will imply that |B_{eN}| ~< 2.7 x 10^{-3} and |B_{μN}| ~< 0.05 at the 90% confidence level.
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Resonant CP Violation in MSSM Higgs Production and Decay at $γγ$ Colliders
We study CP-violating phenomena in the production, mixing and decay of a coupled system of CP-violating neutral Higgs bosons at γγcolliders, assuming a Minimal Supersymmetric Standard Model (MSSM) Higgs sector in which CP violation is radiatively induced by phases in the soft supersymmetry-breaking gaugino masses and third-generation trilinear squark couplings. We discuss CP asymmetries in the production and decays of μ^+ μ^-, τ^+ τ^-, {\bar b} b and {\bar t} t pairs. We find large asymmetries when two (or all three) neutral Higgs bosons are nearly degenerate with mass differences comparable to their decay widths, as happens naturally in the CP-violating MSSM for values of \tanβ>~ 5(30) and large (small) charged Higgs-boson masses.
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Diffraction as a CP and Lineshape Analyzer for MSSM Higgs Bosons at the LHC
We study the production and decay of a coupled system of mixed neutral MSSM Higgs bosons in exclusive double-diffractive processes at the LHC, including non-vanishing CP phases in the soft supersymmetry-breaking gaugino masses and third-generation trilinear squark couplings. The three neutral Higgs bosons are naturally nearly degenerate, for large values of \tanβ, when the charged Higgs boson weighs around 150 GeV. Large mixing between all three neutral Higgs bosons is possible when CP is violated, a three-way mixing scenario which we also term tri-mixing. A resolution in the Higgs mass of \sim 1 GeV, which may be achievable using the missing-mass method, would allow one to distinguish nearly degenerate Higgs bosons by studying the production lineshape. Measurements of the polarizations of the tau leptons coming from the Higgs-boson decays could offer a direct and observable signal of CP violation in the Higgs sector.
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Resonant Higgs-Sector CP Violation at the LHC
We present the general formalism for studying CP-violating phenomena in the production,mixing and decay of a coupled system of CP-violating neutral Higgs bosons at high-energy colliders. Considering the Minimal Supersymmetric Standard Model (MSSM) Higgs sector in which CP violation is radiatively induced by phases of the soft supersymmetry-breaking parameters, we apply our formalism to neutral Higgs production via {\bar b}b, gg and W^+ W^- collisions and their subsequent decays into tau^+ tau^- pairs at the LHC. We discuss CP asymmetries in the longitudinal polarizations of tau^+ tau^- pairs based on a scenario in which all neutral Higgs bosons are nearly degenerate and the CP-violating signatures are resonantly enhanced.
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LHC Signatures of Resonant CP Violation in a Minimal Supersymmetric Higgs Sector
We present the general formalism for studying CP-violating phenomena in the production, mixing and decay of a coupled system of CP-violating neutral Higgs bosons at high-energy colliders. Considering the Minimal Supersymmetric Standard Model (MSSM) Higgs sector in which CP violation is radiatively induced by phases in the soft supersymmetry-breaking third-generation trilinear squark couplings and gaugino masses, we apply our formalism to neutral Higgs production via {\bar b}b, gg and W^+ W^- collisions at the LHC. We discuss CP asymmetries in the longitudinal and transverse polarizations of τ^+ τ^- pairs. The signatures of CP violation are more prominent in the production via gg and W^+ W^- than via {\bar b}b, and are resonantly enhanced when two (or all three) neutral Higgs bosons are nearly degenerate with mass differences comparable to their decay widths. Such scenarios occur naturally in the MSSM for values of \tanβ>~ 5 (30) and large (small) charged Higgs-boson masses. We analyze representative examples with large mixing between the three neutral Higgs bosons weighing about 120 GeV, that may exhibit observable CP asymmetries even as large as 80%.
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Threshold corrections to m_b and the b\bar{b} -> H^0_i production in CP-violating SUSY scenarios
The inclusion of supersymmetric threshold corrections to the $b$-quark mass has dramatic consequences in scenarios with large CP-mixing effects in the Higgs sector. In particular, when the phase of the combination $M_{\tilde{g}}μ$ is $\sim 180^{\rm o} \pm 30^{\rm o}$, the lightest-sbottom squark becomes tachyonic and, possibly, the $b$-quark Yukawa coupling nonperturbative for values of $\tan β$ ranging from intermediate up to large or very large, depending on the size of $arg(A_tμ)$, $arg(A_bμ)$, and the details of the spectrum. For these scenarios, when allowed, as well as scenarios with different values of $arg(M_{\tilde{g}}μ)$, the cross sections for the production of the three neutral-Higgs bosons through $b$-quark have rather interesting dependences on $arg(A_tμ)$ and $arg(A_bμ)$, and the deviations induced by the $m_b$ corrections are rather large. In general, such production channel cannot be neglected with respect to the production through gluon fusion. For large CP-mixing effects, the lightest neutral-Higgs boson can be mainly CP odd and the $b$-quark fusion becomes its main production mechanism. Searches at the Tevatron and the LHC can easily detect such a Higgs boson, or constrain the CP-violating scenarios that allow it.
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Wrong-sign Kaons in B decays and New Physics
New physics can possibly emerge in the B decays into wrong-sign kaons for which the standard model contributions are extremely suppressed. We analyze two-body decays of $\bar{B}^0$ and $B^-$ mesons involving the $b\to dd\bar{s}$ ($ΔS=-1$) and $b\to ss\bar{d}$ ($ΔS=+2$) transitions in a model independent way, and examine various wrong-sign kaon signals which are expected to be observed in the future $B$ experiments. Our analysis shows that it would be possible to identify the origin of new physics through the combined analysis of several B decay modes involving one or two wrong-sign $K^*$'s.
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Novel constraints on $ΔL=1$ interactions from neutrino masses
We reanalyze the constraints imposed on lepton-number violating interactions by radiative contributions to neutrino masses at the one- and two-loop level in supersymmetric models without R-parity. The interactions considered are the $ΔL=1$ superpotential operators $λ_{ijk} L_i L_j E^c_k$ and $λ^\prime_{ijk} L_i Q_j D^c_k$, and the $ΔL=1$ soft terms $A_{ijk} \tilde{L}_i \tilde{L}_j \tilde{E}^c_k$ and $A_{ijk}^\prime \tilde{L}_i \tilde{Q}_j \tilde{D}^c_k$. It is shown how the constraints on the couplings $λ_{ijk}$ and $λ^\prime_{ijk}$ coming from the one-loop analysis can be evaded. In such a case, the two-loop contributions to neutrino masses become important. The combined one- and two-loop analysis yields constraints on the couplings $λ_{i33}$ and $λ^\prime_{i33}$ that are rather difficult to escape. The two-loop analysis yields also new constraints on $A_{i33}$ and $A^\prime_{i33}$, which are not bounded at the one-loop level. More freedom remains for couplings $λ_{ijk}$, $λ^\prime_{ijk}$, and $A_{ijk}$, $A^\prime_{ijk}$, when $j$ and $k$ are first- or second-generation indices.
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3- and 2-body supersymmetric processes: predictions, challenges and prospectives
The processes subject of this talk are: 1) the 2 --> 3 processes contributing, together with the 2 --> 2 one to the hadron-collider production of a charged Higgs boson in association with a t-quark; 2) the 2 --> 2 and 2 --> 3 processes giving rise to the hadron-collider strahlung of a charged slepton from a t-quark in R_p-violating models in which lepton-number-violating trilinear couplings largely dominate over bilinear ones; 3) 3-body neutralino and chargino decays in similar R_p-violating scenarios. The significance of the R_p-violating processes is critically assessed against implications from neutrino physics. Contributions to neutrino masses arising at the tree level, at the one- and two-loop levels are reviewed. Comments are also made on the production of sneutrinos via gluon fusion and on the decay of sneutrinos into photons pairs, and on the influence that constraints from neutrino physics have on these processes.
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CP--violating Chargino Contributions to the Higgs Coupling to Photon Pairs in the Decoupling Regime of Higgs Sector
In most supersymmetric theories, charginos $\tildeχ^\pm_{1,2}$ belong to the class of the lightest supersymmetric particles and the couplings of Higgs bosons to charginos are in general complex so that the CP--violating chargino contributions to the loop--induced coupling of the lightest Higgs boson to photon pairs can be sizable even in the decoupling limit of large pseudoscalar mass $m_A$ with only the lightest Higgs boson kinematically accessible at future high energy colliders. We introduce a specific benchmark scenario of CP violation consistent with the electric dipole moment constraints and with a commonly accepted baryogenesis mechanism in the minimal supersymmetric Standard Model. Based on the benchmark scenario of CP violation, we demonstrate that the fusion of the lightest Higgs boson in linearly polarized photon--photon collisions can allow us to confirm the existence of the CP--violating chargino contributions {\it even in the decoupling regime of the Higgs sector} for nearly degenerate SU(2) gaugino and higgsino mass parameters of about the electroweak scale.
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Supersymmetric Higgs Boson Decays in the MSSM with Explicit CP Violation
Decays into neutralinos and charginos are among the most accessible supersymmetric decay modes of Higgs particles in most supersymmetric extensions of the Standard Model. In the presence of explicitly CP--violating phases in the soft breaking sector of the theory, the couplings of Higgs bosons to charginos and neutralinos are in general complex. Based on a specific benchmark scenario of CP violation, we analyze the phenomenological impact of explicit CP violation in the Minimal Supersymmetric Standard Model on these Higgs boson decays. The presence of CP--violating phases could be confirmed either directly through the measurement of a CP--odd polarization asymmetry of the produced charginos and neutralinos, or through the dependence of CP--even quantities (branching ratios and masses) on these phases.
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Observability of the Lightest MSSM Higgs Boson with Explicit CP Violation via Gluon Fusion at the LHC
We investigate the observability of the lightest Higgs boson in the gluon-fusion channel at the CERN Large Hadron Collider (LHC) in the minimal supersymmetric Standard Model with explicit CP-violating mixing among three neutral Higgs bosons. The lightest Higgs boson with its mass less than 130 GeV can be detected at the LHC via its gluon-fusion production followed by the decay into two photons. The explicit CP violation can suppress both the production cross section and the two-photon decay branching fraction so significantly that the signal cross section may be more than ten times smaller than the SM signal. This reduction factor can be as small as 1/40 if the lightest Higgs boson mass is 115 GeV and its production cross section at LEP2 is more than 90 % that of the SM case.
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