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Learning from Higgs Physics at Future Higgs Factories

Jiayin Gu; Honglei Li; Zhen Liu; Shufang Su; Wei SuSubjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

Future Higgs factories can reach impressive precision on Higgs property measurements.In this paper, instead of conventional focus of Higgs precision in certain interaction bases, we explored its sensitivity to new physics models at the electron-positron colliders. In particular, we studied two categories of new physics models, Standard Model (SM) with a real scalar singlet extension, and Two Higgs Double Model (2HDM) as examples of weaklyinteracting models, Minimal Composite Higgs Model (MCHM) and three typical patterns of the more general operator counting for strong nteracting models as examples of strong dynamics. We performed a global t to various Higgs search channels to obtain the 95% C.L.constraints on the model parameter space. In the SM with a singlet xtension, we obtained the limits on the singlet-doublet mixing angle sin , as well as the more general Wilson coe cients of the induced higher dimensional operators. In the 2HDM, we analyzed tree level e ects in tan vs. cos(β-α) plane, as well as the one-loop contributions from the heavy Higgs bosons in the alignment limit to obtain the constraints on heavy Higgs masses for di erent types of 2HDM. In strong dynamics models, we obtained lower limits on the strong dynamics scale. In addition, once deviations of Higgs couplings are observed, they can be used to distinguish di erent models. We also compared the sensitivity of various future Higgs factories,namely Circular Electron Positron Collider (CEPC), Future Circular Collider (FCC)-ee and International Linear Collider (ILC). |

Modeling Charmonium-η Decays of JP C = 1?? Higher Charmonia

Muhammad Naeem Anwar; Yu Lu; Bing-Song ZouSubjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

We propose a new model to create a light meson in the heavy quarkonium transition, which is inspired by the Nambu?Jona-Lasinio (NJL) model. Hadronic transitions of JPC = 1?? higher char-monia with the emission of an η meson are studied in the framework of the proposed model. The model shows its potential to reproduce the observed decay widths and make predictions for the unobserved channels. We present our predictions for the decay width of Ψ → J/ η and Ψ → hc(1P )η, where Ψ are higher S and D wave vector charmonia, which provide useful references to search for higher char-monia and determine their properties in forthcoming experiments. The predicted branching fraction B( (4415) → hc(1P )η) = 4.62 × 10?4 is one order of magnitude smaller than the J/ η channel. Esti-mates of partial decay width Γ(Y → J/ η) are given for Y (4360), Y (4390) and Y (4660) by assuming them as cc? bound states with quantum numbers 33D1, 33D1 and 53S1, respectively. Our results are in favor of these assignments for Y (4360) and Y (4660). The corresponding experimental data for these Y states has large statistical errors which do not provide any constraint on the mixing angle if we introduce S ?D mixing. To identify Y (4390), precise measurements on its hadronic branching fraction are required which are eagerly awaited from BESIII. |

Effects of Zb states and bottom meson loops on γ(4S)→γ(1S, 2S)π+π? transitions

Yun-Hua Chen; Martin Cleven; Johanna T. Daub; Feng-Kun Guo; Christoph Hanhart; Bastian Kubis; Ulf-G. Mei遪er; Bing-Song ZouSubjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

We study the dipion transitions (4S) → (nS)π+π? (n = 1, 2). In particular, we consider the effects of the two intermediate bottomoniumlike exotic states Zb(10610) and Zb(10650) as well as bottom meson loops. The strong pion–pion final-state interactions, especially including channel coupling to K ?K in the S-wave, are taken into account modelindependently by using dispersion theory. Based on a nonrelativistic effective field theory we find that the contribution from the bottom meson loops is comparable to those from the chiral contact terms and the Zb-exchange terms. For the (4S) → (2S)π+π? decay, the result shows that including the effects of the Zb-exchange and the bottom meson loops can naturally reproduce the two-hump behavior of the ππ mass spectra. Future angular distribution data are decisive for the identification of different production mechanisms. For the (4S) → (1S)π+π? decay, we show that there is a narrow dip around 1GeV in the ππ invariant mass distribution, caused by the final-state interactions. The distribution is clearly different from that in similar transitions from lower states, and needs to be verified by future data with high statistics. Also we predict the decay width and the dikaon mass distribution of the (4S) → (1S)K+K? process. |

Coupled-Channel Effects for the Bottomonium with Realistic Wave Functions

Yu Lu; Muhammad Naeem Anwar; Bing-Song ZouSubjects: Physics >> Nuclear Physics

With Gaussian expansion method (GEM), realistic wave functions are used to calculate coupled-channel effects for the bottomonium under the framework of?3P0?model. The simplicity and accuracy of GEM are explained. We calculate the mass shifts, probabilities of the?B?meson continuum,?S?D?mixing angles, strong and dielectric decay widths. Our calculation shows that both?S?D?mixing and the?B?meson continuum can contribute to the suppression of the vector meson's dielectric decay width. We suggest more precise measurements on the radiative decays of?Υ(10580)?and?Υ(11020)?to distinguish these two effects. The above quantities are also calculated with simple harmonic oscillator (SHO) wave function approximation for comparison. The deviation between GEM and SHO indicates that it is essential to treat the wave functions accurately for near threshold states. |

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