All Results

Beyond Higgs Couplings: Probing the Higgs with Angular Observables at Future e$^+$ e$^?$ Colliders

Nathaniel Craig; Jiayin Gu; Zhen Liu; Kechen WangSubjects: Physics >> Nuclear Physics

We study angular observables in the?e+e?→ZH→?+??bb??channel at future circular?e+e??colliders such as CEPC and FCC-ee. Taking into account the impact of realistic cut acceptance and detector effects, we forecast the precision of six angular asymmetries at CEPC (FCC-ee) with center-of-mass energy?s√=?240 GeV and 5 (30)?ab?1?integrated luminosity. We then determine the projected sensitivity to a range of operators relevant for the Higgs-strahlung process in the dimension-6 Higgs EFT. Our results show that angular observables provide complementary sensitivity to rate measurements when constraining various tensor structures arising from new physics. We further find that angular asymmetries provide a novel means of both probing BSM corrections to the?HZγ?coupling and constraining the "blind spot" in indirect limits on supersymmetric scalar top partners. |

Subjects: Physics >> Nuclear Physics

Double polarized forward-backward asymmetries in?B→K1(1270,1400)?+???with??=μ,τ?decays are studied, using most general non-standard local four-fermi interactions, where the mass eigenstates?K1(1270)?and?K1(1400)?are the mixture of?1P1?and?3P1?states with the mixing angle?θK. We have calculated the expressions of nine doubly polarized forward-backward asymmetries and it is presented that the polarized lepton pair forward-backward asymmetries are greatly influenced by the new physics. Therefore, these asymmetries are interesting tool to explore the status of new physics in near future, specially at LHC. |

The $ Zb\overlineb $ couplings at future e$^+$ e$^?$ colliders

Stefania Gori; Jiayin Gu; Lian-Tao Wang(c; d)Subjects: Physics >> Nuclear Physics

Many new physics models predict sizable modifications to the SM Zbb couplings, while the corresponding measurements at LEP and SLC exhibit some discrepancy with the SM predictions. After updating the current results on the Zbb coupling constraints from global fits, we list the observables that are most important for improving the Zbb coupling constraints and estimate the expected precision reach of three proposed future e+e- colliders, CEPC, ILC and FCC-ee. We consider both the case that the results are SM-like and the one that the Zbb couplings deviate significantly from the SM predictions. We show that, if we assume the value of the Zbb couplings to be within 68% CL of the current measurements, any one of the three colliders will be able to rule out the SM with more than 99.9999% CL (5 sigma). We study the implications of the improved Zbb coupling constraints on new physics models, and point out their complementarity with the constraints from the direct search of new physics particles at the LHC, as well as with Higgs precision measurements. Our results provide a further motivation for the construction of future e+e- colliders. |

Subjects: Physics >> Nuclear Physics

We study?S-wave resonance contributions to the?B0(s)→J/ψπ+π??and?Bs→π+π??+???decays in the perturbative QCD (PQCD) framework by introducing two-hadron distribution amplitudes for final states. The Breit-Wigner formula for the?f0(500),?f0(1500)?and?f0(1790)?resonances and the Flatt\'e model for the?f0(980)resonance are adopted to parameterize the time-like scalar form factors in the two-pion distribution amplitudes, which include both resonant and nonresonant contributions. The resultant branching fraction and differential branching fraction in the pion-pair invariant mass for each resonance channel are consistent with experimental data. The determined?S-wave two-pion distribution amplitudes, containing the information of both resonant and nonresonant rescattering phases, can be employed to predict direct CP asymmetries of other three-body hadronic?B?meson decays in various localized regions of two-pion phase space. |

[1 Pages/ 4 Totals]