In this paper, we study the next-to-next-to-leading-order (NNLO) QCD corrections for the process $e^+e^- \to J/ψ+J/ψ$ at the $B$ factories. By including the NNLO corrections, the cross section turns negative due to the poor convergence of perturbative expansion. Consequently, to obtain a reasonable estimation for the cross section, the square of the amplitude up to NNLO is used. In addition, the contributions from the bottom quark and the light-by-light part, which are usually neglected, are also included. The final cross section is obtained as $1.76^{+2.42}_{-1.66} ~{\rm fb}$ at a center-of-mass energy of $\sqrt{s}=10.58$ GeV. Our result for total cross section and differential cross section could be compared with precise experimental measurement in future at the $B$ factories.
In this paper, we calculate the next-to-next-to-leading-order (NNLO) QCD corrections to $e^+e^- \to J/ψ+η_c$ at the $B$ factories. After including the NNLO corrections, the cross section of $e^+e^- \to J/ψ+η_c$ is enhanced by about $17\%$, and the perturbative series of the prediction shows the convergent behavior. It is also found that the contribution from bottom quark starts at the $α_s^3$-order, which is about $2.4\%$ of the total prediction. The renormalization scale $μ_R$ dependence of the cross section is reduced at the NNLO level, but the prediction is sensitive to the charm quark mass…
Within the nonrelativistic QCD (NRQCD) factorization framework, we compute the long-awaited ${\mathcal O}(α_s^2)$ correction for the exclusive double charmonium production process at $B$ factories, {\it i.e.}, $e^+e^-\to J/ψ+η_c$ at $\sqrt{s}=10.58$ GeV. For the first time, we confirm that NRQCD factorization does hold at next-to-next-to-leading-order (NNLO) for exclusive double charmonium production. It is found that including the NNLO QCD correction considerably reduces the renormalization scale dependence, and also implies the reasonable perturbative convergence behavior for this process. O…
By including the interference effect between the QCD and the QED diagrams, we carry out a complete analysis on the exclusive productions of $e^+e^- \to J/ψ+χ_{cJ}$ ($J=0,1,2$) at the $B$ factories with $\sqrt{s}=10.6$ GeV at the next-to-leading-order (NLO) level in $α_s$, within the nonrelativistic QCD framework. It is found that the $\mathcal O (α^3α_s)$-order terms that represent the tree-level interference are comparable with the usual NLO QCD corrections, especially for the $χ_{c1}$ and $χ_{c2}$ cases. To explore the effect of the higher-order terms, namely $\mathcal O (α^3α_s^2)$, we perf…
The Semileptonic B Frontier: LHC, B-factories, Lattice QCD & the Hunt for Precision
INFN, Sezione di Bari(意大利国家核物理研究所巴里分部);Laboratori Nazionali di Frascati(弗拉斯卡蒂国家实验室);PRISMA ++ Cluster of Excellence & Mainz Institute for Theoretical Physics, Johannes Gutenberg University(约翰内斯·古腾堡大学);ICCUB, Universitat de Barcelona(巴塞罗那大学);Department of Physics and Astronomy, University of Manchester(曼彻斯特大学);Aix Marseille Univ, CNRS/IN2P3, CPPM(艾克斯-马赛大学);Dipartimento di Fisica e Astronomia Galileo Galilei & INFN, Università di Padova(帕多瓦大学);Dipartimento di Fisica & INFN, Università di Torino(都灵大学);INFN, Sezione di Roma Tre(意大利国家核物理研究所罗马第三大学分部)
The electroweak phase transition can be made first order by extending the Standard Model (SM) Higgs sector with extra scalars. The same new physics can explain the matter-antimatter asymmetry of the universe by supplying an extra source of CP violation and sphaleron processes. In this paper we study the existence of a strong first order electroweak phase transition (SFOEWPT) in the type-I and type-II two Higgs doublet models (2HDM). We focus on how the SFOEWPT requirement constraints the spectrum of non-SM Higgs. Through a parameter space scan, we find that SFOEWPT suggests upper limits on the…
The full one-loop corrections, both the weak and QED corrections, to the process $e^+ e^- \to Z ϕ$ ($ϕ=h^0,H^0$) in the two Higgs doublet model (2HDM) at the Higgs factories are presented. Up to the $O(α_{em})$ level, the virtual corrections are evaluated by using the FeynArts/FormCalc packages. The real emission corrections are computed using the Feynman Diagram Calculation (FDC) package and the collinear divergences are regularized by the structure functions of an electron. Using the FeynArts/FormCalc and the FDC packages, we study the corrections in the Standard Model (SM) and the 2HDM, res…
We present a generalisation of the double-logarithmic equation for the anomalous dimension of the non-singlet unpolarized twist-2 operators in QCD. Using the known three-loop result, this generalisation allows to predict a small x expansion of the four-loop non-singlet splitting functions in QCD for all powers of logarithms up to the single-logarithm term.
In this paper we review the hadroproduction mechanisms of double-charm baryons for the different experimental environments and reinterpret the SELEX and LHCb results.
We compute the master integrals required for the calculation of the double-real emission contributions to the matching coefficients of 0-jettiness beam functions at next-to-next-to-next-to-leading order in perturbative QCD. As an application, we combine these integrals and derive the double-real gluon emission contribution to the matching coefficient $I_{qq}(t,z)$ of the quark beam function.