정성훈 교수

Motivated by recent measurements of the top quark forward-backward asymmetry at the Tevatron, we study how $t$-channel new physics can contribute to a large value. We concentrate on a theory with an Abelian gauge boson that possesses flavor changing couplings between up and top quarks but satisfies flavor physics constraints. Collider constraints are strong, but can be accommodated with the aid of small flavor-diagonal couplings. We find that ${M}_{{Z}^{\ensuremath{'}}}\ensuremath{\approx}160\te

Utilizing gravitational-wave (GW) lensing opens a new way to understand the small-scale structure of the Universe. We show that, in spite of its coarse angular resolution and short duration of observation, LIGO can detect the GW lensing induced by small structures, in particular by compact dark matter (DM) or the primordial black hole of 10-10^{5} M_{⊙}, which remains an interesting DM candidate. The lensing is detected through GW frequency chirping, creating the natural and rapid change of lens

Motivated by the persistence of a large measured top quark forward-backward asymmetry at the Tevatron, we examine a model of non-Abelian flavor gauge symmetry. The exchange of the gauge bosons in the $t$-channel can give a large ${A}_{\mathrm{FB}}^{t}$ due to the forward Rutherford scattering peak. We address generic constraints on non-Abelian $t$-channel physics models including flavor diagonal resonances and potentially dangerous contributions to inclusive top pair cross sections. We caution o

We show that new resonance shapes---a pure dip, nothingness, and an enhanced pure peak---can be produced from the interference between the resonance and continuum with a relative phase. Production conditions of those new shapes are derived based on a general parametrization of the interference. The narrow width approximation is modified to work with the nonzero imaginary part of interference, and the correction factor can characterize the resonance shape. We demonstrate that the new resonance sh

We investigate the prospects of discovering split Supersymmetry at a future 100 TeV proton-proton collider through the direct production of electroweakino next-to-lightest- supersymmetric-particles (NLSPs). We focus on signatures with multi-lepton and missing energy: 3ℓ, opposite-sign dileptons and same-sign dileptons. We perform a comprehensive study of different electroweakino spectra. A 100 TeV collider with 3000/fb data is expected to exclude Higgsino thermal dark matter candidates with m LS

We derive new limits on light stops from diboson resonance searches in the γγ, Zγ, ZZ, WW and hh channels from the first run of the LHC. If the two-body decays of the light stop are mildly suppressed or kinematically forbidden, stoponium bound states will form in pp collisions and subsequently decay via the pair annihilation of the constituent stops to diboson final states, yielding striking resonance signatures. Remarkably, we find that stoponium searches are highly complementary to direct coll

A hypothetical new scalar resonance, a candidate explanation for the recently observed 750 GeV diphoton excess at the LHC 13 TeV, necessarily interferes with the continuum background gg → γγ. The interference has two considerable effects: (1) enhancing or suppressing diphoton signal rate due to the imaginary-part interference and (2) distorting resonance shape due to the real-part interference. We study them based on the best-fit analysis of two benchmark models: two Higgs doublets with ∼50 GeV

CDF recently reported an anomaly in the ${m}_{jj}$ distribution of dijet events produced in association with a $W$ boson. A single $u\ensuremath{-}t\ensuremath{-}V$ flavor-changing coupling can contribute to the ${m}_{jj}$ anomaly while being consistent with other resonance searches. Furthermore, it gives a potential explanation of the observed forward-backward asymmetry in top quark production.

Discovery of the Higgs boson and lack of discovery of superpartners in the first run at the LHC are both predictions of split supersymmetry with thermal dark matter. We discuss what it would take to find gluinos at hadron supercolliders, including the LHC at 14 TeV center-of-mass energy, and future $pp$ colliders at 100 TeV and 200 TeV. We generalize the discussion by reexpressing the search capacity in terms of the gluino to lightest superpartner mass ratio and apply results to other scenarios,

The axion-gravity Chern-Simons coupling is well motivated but is relatively weakly constrained, partly due to difficult measurements of gravity. We study the sensitivity of LIGO measurements of chirping gravitational waves (GWs) on such coupling. When the frequency of the propagating GW matches with that of the coherent oscillation of axion dark matter field, the decay of axions into gravitons can be stimulated, resonantly enhancing the GW. Such a resonance peak can be detected at LIGO as a devi

The world society of 21st century started with the mega-terrorism and the so-called ‘just’ war. But just war has broken the international law. In Asia, the constitutional court of Korea judged the political decision for the shift of administrative capital as illegal, but this judge has disregarded the positive constitutional law of Korea. I regard these cases and another cases which occur in several regions of world society as the symptom of law being undermined(das Unterminiertwerden des Rechts

The exchange of a light $t$-channel flavor-changing gauge boson, ${V}^{\ensuremath{'}}$, with mass $\ensuremath{\sim}{m}_{\mathrm{top}}$ remains a leading explanation for the anomalous forward-backward asymmetry in top-quark production at the Tevatron. Unlike other ideas, including heavier $t$-channel mediators, the light ${V}^{\ensuremath{'}}$ model is not easily seen in the ${m}_{t\overline{t}}$ distribution. We advocate a more promising strategy. While current analyses at hadron colliders may

Motivated by recent measurements of the top quark forward-backward asymmetry at the Tevatron, we study how t-channel new physics can contribute to a large value. We concentrate on a theory with an abelian gauge boson possessing flavor changing couplings between up and top quarks, but satisfies flavor physics constraints. Collider constraints are strong, but can be consistent with the aid of small flavor diagonal couplings. We find that M_Z' ~ 160 GeV can yield a total lab-frame asymmetry of ~18%

We study the renormalization group(RG) evolution of four-quark operators that contribute to the top pair production. In particular, we focus on the cases in which certain observables are first induced from the one-loop RG while being absent at tree-level. From the operator mixing pattern, we classify all such RG-induced phenomena and underlying models that can induce them. We then calculate the full one-loop QCD RG evolution as the leading estimator of the effects and address the question of whi