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Register a new userGauge Dependences of Higher-Order Corrections to NMSSM Higgs Boson Masses and the Charged Higgs Decay $H^pm to W^pm h_i$
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In this paper we compute the electroweak corrections to the charged Higgs boson decay into a $W$ boson and a neutral Higgs boson in the CP-conserving NMSSM. We calculate the process in a general $R_xi$ gauge and investigate the dependence of the loop-corrected decay width on the gauge parameter $xi$. The gauge dependence arises from the mixing of different loop orders. Phenomenology requires the inclusion of mass and mixing corrections to the external Higgs bosons in order to match the experimentally measured mass values. As a result, we move away from a strict one-loop calculation and consequently mix orders in perturbation theory. Moreover, determination of the loop-corrected masses in an iterative procedure also results in the mixing of different loop orders. Gauge dependence then arises from the mismatch with tree-level Goldstone boson couplings that are applied in the loop calculation, and from the gauge dependence of the loop-corrected masses themselves. We find that the gauge dependence is significant.
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In certain new physics scenarios, a singly charged Higgs boson can couple to both fermions and $W^pm Z$ at tree level. We develop new strategies beyond current experimental searches using $ppto jjH^pm$, $H^pm to tb $ at the Large Hadron Collider (LHC). With the effective $H^pm W^mp Z$ and $H^pm tb$ couplings we perform a model-independent analysis at the collision energy $sqrt{s}=13$~TeV with the integrated luminosity of $3~text{ab}^{-1}$. We derive the discovery prospects and exclusion limits for the charged Higgs boson in the mass range from 200~GeV to 1~TeV. With $|F_{WZ}|,|A_t|sim 0.5-1.0$ and $300~text{GeV}lesssim m_{H^pm}lesssim 400~text{GeV}$, we point out that a discovery significance of $5sigma$ can be achieved. The constraints and projected sensitivities are also discussed in a realistic model, i.e., the modified Georgi-Machacek model without custodial symmetry. Our proposed search would provide direct evidence for a charged Higgs boson $H^pm$ that couples to $W^pm Z$ and $tb$, which can have better sensitivity to the couplings of $H^pm W^mp Z$ and $H^pm tb$ than current searches.
After the discovery of a Higgs-like boson by the LHC experiments ATLAS and CMS, it is of crucial importance to determine its properties in order to not only identify it as the boson responsible for electroweak symmetry breaking but also to clarify the question if it is a Standard Model (SM) Higgs boson or the Higgs particle of some extension beyond the SM as {it e.g.} supersymmetry. In this context, the precise prediction of the Higgs parameters as masses and couplings play a crucial role for the proper distinction between different models. In extension of previous works on the loop-corrected Higgs boson masses of the Next-to-Minimal Supersymmetric Extension of the SM (NMSSM), we present here the calculation of the loop-corrected trilinear NMSSM Higgs self-couplings. The loop corrections turn out to have a substantial impact on the decay widths of Higgs-to-Higgs decays and on the production cross section of Higgs pairs via gluon fusion. They are therefore indispensable for the correct interpretation of the experimental Higgs results.
Theoretical predictions for the decay width of Standard Model Higgs boson into bottom quarks and tau-leptons, in the case when M_H< 2M_W, are briefly reviewed. The effects of higher order perturbative QCD (up to alpha_s^4-level) and QED corrections are considered. The uncertainties of the decay width of Higgs boson into bb and tau+tau- are discussed.
The exclusive decay of the Higgs boson to a vector meson ($ J/psi $ or $ Upsilon(1S) $) and $ Z $ boson is studied in this work. The decay amplitudes are separated into two parts in a gauge invariant manner. The first part comes from the direct coupling of the Higgs boson to the charm (bottom) quark and the other from the $ HZZ^{*} $ or the loop-induced $ HZgamma^{*} $ vertexes in the standard model. While the branching ratios from the direct channel are much smaller than those of the indirect channel, their interference terms give nontrivial contributions. We further calculate the QCD radiative corrections to both channels, which reduce the total branching ratios by around 20% for both $ J/psi $ and $ Upsilon(1S) $ production. These results may help to check the SM predictions of the $ H cbar{c}(H bbar{b}) $ coupling and to seek for hints of new physics at the High Luminosity LHC or future hadron colliders.
The process $H to J/psi + gamma$, where $H$ is the Higgs particle, provides a way to probe the size and the sign of the Higgs-charm coupling. In order to improve the theoretical control of the decay rate, we compute order $v^4$ corrections to the decay rate based on the nonrelativistic QCD factorization formalism. The perturbative calculation is carried out by using automated computer codes. We also resum logarithms of the ratio of the masses of the Higgs boson and the $J/psi$ to all orders in the strong coupling constant $alpha_s$ to next-to-leading logarithmic accuracy. In our numerical result for the decay rate, we improve the theoretical uncertainty, while our central value is in agreement with previous studies within errors. We also present numerical results for $H to Upsilon(nS) + gamma$ for $n=1,2$, and 3, which turn out to be extremely sensitive to the Higgs bottom coupling.
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