Mixed electroweak-QCD corrections to e^+e^-→μ^+μ^-H at CEPC with finite-width effect

The associated production of Higgs boson with a muon pair, e^+e^-→μ+μ-H, is one of the golden channels to pin down the properties of the Higgs boson in the prospective Higgs factories exemplified by CEPC.The projected accuracy of the corresponding cross section measurement is about per cent level at CEPC. In this work, we investigate both O(α) weak correction and the O(ααs) mixed electroweak-QCD corrections for this channel,appropriately taking into account the effect of finite Z^0 width. The μ^+μ^-invariant mass spectrum is also predicted.The mixed electroweak-QCD correction turns out to reach 1.5% of the Born-order result, and thereby must be included in future confrontation with the data. We also observe that, after including higher-order corrections, the simplified prediction for the integrated cross section employing the narrow-width-approximation may deviate from our full result by a few per cents.

QCD corrections to e^+e^−→H^±W^∓in Type-I THDM at electron positron colliders

We investigate in detail the charged Higgs production associated with a W boson at electron-positron colliders within the framework of the Type-I two-Higgs-doublet model(THDM).We calculate the integrated cross section at the LO and analyze the dependence of the cross section on the THDM parameters and the colliding energy in a benchmark scenario of the input parameters of the Higgs sector.The numerical results show that the integrated cross section is sensitive to the charged Higgs mass,especially in the vicinity of mH±≃184 GeV at a 500 GeV e^+e^−collider,and decreases consistently with the increase of tanβin the low tanβregion.The peak in the colliding energy distribution of the cross section arises from the resonance of the loop integrals,and it moves towards the low colliding energy with the increase of mH±.We also study the two-loop NLO QCD corrections to both the integrated cross section and the angular distribution of the charged Higgs boson and find that the QCD relative correction is also sensitive to the charged Higgs mass and strongly depends on the final-state phase space.For tanβ=2,the QCD relative correction at a 500 GeV e^+e^−collider varies in the range of[-10%,11%]as mH±increases from 150 to 400 GeV.

Littlest Higgs Model and Spin Correlation of Top Quark Production at High Energy Linear e^＋e^- Colliders

Based on the littlest Higgs model, we investigate the spin correlation of the top quark pair production via the process e^＋e^- →tt at the high energy linear e^＋e^- collider （ILC） with a centre-of-mass energy √S = 800 GeV. Our numerical results show that the gauge boson ZH generates very small corrections to the spin correlation observable C in all the parameter space allowed by the electroweak data. However, with reasonable values of the free parameters, the value of the relative correction parameter RBH = （CBH-CSM）/CSM can reach 10%, which might be detected in future ILC experiments.

Accurate Calculation of the Differential Cross Section of Bhabha Scattering with Photon Chain Loops Contribution in QED

In the minimum electromagnetism coupling model of interaction between photon and electron （positron）, we accurately calculate photon chain renormalized propagator and obtain the accurate result of differential cross section of Bhabha scattering with a photon chain renormalized propagator in quantum electrodynamics. The related radiative corrections are briefly reviewed and discussed.

QCD and electro-weak corrections to the production of Higgs+2 jets at the LHC

We present complete next-to-leading-order(NLO)QCD correction and electro-weak(EW)correction to the production cross section of Higgs–Boson in association with two hard quark jets by using Monte-Carlo numerical calculation program,HAWK,for various photon parton distribution functions at the Large Hadron Collider with center of mass energy 7,8,13,and 14 TeV without and with typical vector-Boson-fusion cuts on the tagging jets.In our calculation we include complete contribution from the full set of t-channel,u-channel and s-channel Feynman diagrams,and corresponding interferences as well as NLO QCD and EW corrections.

eμ Production in R-Parity Violating Supersymmetric Model at Hadron Colliders

We investigate the lepton flavor violating productions pp/pp→eμ ＋ X in the framework of the R-parity violating （RPV） supersymmetric model at the Tevatron and the CERN large hadron collider （LHC）. We present the total cross sections including the next-to-leading order （NLO） QCD corrections and the contribution from gluon-gluon fusion subprocess. Our numerical results show that the one-loop QCD corrections significantly increase the tree-level cross sections, and the variation of K factor is in the range between 1.28 （1.32） and 1.79 （1.58） at the Tevatron （LHC）. We find that the QCD correction from the one-loop gluon-gluon fusion subprocess is remarkable at the LHC and should be taken into account.

Next-to-leading order QCD and electroweak corrections to Higgs-strahlung processes at the LHC

In this paper we calculate the total and fiducial cross sections as well as differential distributions for the Higgs-strahlung or VH process pp→VH→lv1/1^-1~＋＋H,（V = W or Z, 1=e, μ） including QCD and electro-weak corrections up to next-to-leading order before and after reweighting photon PDFs of NNPDF2.3 qed, NNPDF3.0 qed,MRST2004 qed, CT14 QEDinc, and LUXqed at the LHC with 13 TeV and Higgs boson mass MH = 125 GeV. The predictions from the various photon PDFs before and after reweighting against each other are in good agreement.The photon PDF uncertainties of the photon-induced cross sections decrease significantly with the reweighting PDFs.

Revisiting the top-quark pair production at future e^(+)e^(−)colliders

In this study,we reanalyze the top-quark pair production at next-to-next-to-leading order(NNLO)in quantum chromodynamics(QCD)at future e^(+)e^(−)colliders using the Principle of Maximum Conformality(PMC)method.The PMC renormalization scales inαs are determined by absorbing the non-conformalβterms by recursively using the Renormalization Group Equation(RGE).Unlike the conventional scale-setting method of fixing the scale at the center-of-mass energyμ_(r)=√s,the determined PMC scale Q_(⋆)is far smaller than the √sand increases with the √s,yielding the correct physical behavior for the top-quark pair production process.Moreover,the convergence of the pQCD series for the top-quark pair production is greatly improved owing to the elimination of the renormalon divergence.For a typical collision energy of √s=500 GeV,the PMC scale is Q_(⋆)=107 GeV;the QCD correction factor K for conventional results is K∼1+0.1244+0.0102+0.0012−0.0087−0.0011+0.0184−0.0086+0.0002+0.0061−0.0003,where the first error is caused by varying the scaleμr∈[√s/2,2√s]and the second error is from the top-quark massΔm_(t)=±0.7 GeV.After applying the PMC,the renormalization scale uncertainty is eliminated,and the QCD correction factor K is improved to K∼1+0.1507_(−0.0015)^(+0.0015)−0.0057_(−0.0000)^(+0.0001),where the error is from the top-quark massΔm_(t)=±0.7 GeV.The PMC improved predictions for the top-quark pair production are helpful for detailed studies of the properties of the top-quark at future e^(+)e^(−)colliders.

A comprehensive revisit of the ρ meson with improved Monte-Carlo based QCD sum rules

We improve the Monte-Carlo based QCD sum rules by introducing the rigorous Hoolder-inequalitydetermined sum rule window and a Breit-Wigner type parametrization for the phenomenological spectral function.In this improved sum rule analysis methodology, the sum rule analysis window can be determined without any assumptions on OPE convergence or the QCD continuum. Therefore, an unbiased prediction can be obtained for the phenomenological parameters（the hadronic mass and width etc.）. We test the new approach in the ρ meson channel with re-examination and inclusion of αs corrections to dimension-4 condensates in the OPE. We obtain results highly consistent with experimental values. We also discuss the possible extension of this method to some other channels.

Analytic two-loop master integrals for tW production at hadron colliders:Ⅰ

We present the analytic calculation of two-loop master integrals that are relevant for tW production at hadron colliders.We focus on the integral families with only one massive propagator.After selecting a canonical basis,the differential equations for the master integrals can be transformed into the d In form.The boundaries are determined by simple direct integrations or regularity conditions at kinematic points without physical singularities.The analytical results in this work are expressed in terms of multiple polylogarithms,and have been checked via numerical computations.

Nuclear 0ν2βdecays in B-L symmetric SUSY model and in TeV scale left–right symmetric model

In this paper,we take the B-L supersymmetric standard model(B-LSSM)and TeV scale left–right symmetric model(LRSM)as two representations of the two kinds of new physics models to study the nuclear neutrinoless double beta decays(0ν2β)so as to see the senses onto these two kinds of models when the decays are taken into account additionally.Within the parameter spaces allowed by all the existing experimental data,the decay half-life of the nucleus^(76)Ge and^(136)Xe,T_(12)^(0ν)(^(76)Ge,^(136)Xe),is precisely calculated and the results are presented properly.Based on the numerical results,we conclude that there is greater room for LRSM type models than for B-LSSM type models in foreseeable future experimental observations on the decays.

Properties of the free energy density using the principle of maximum conformality

We present a detailed study on the properties of the free energy density at high temperature by applying the principle of maximum conformality（PMC）scale-setting method within effective field theory.The PMC utilizes the renormalization group equation recursively to identify the occurrence and pattern of the non-conformal{βi}-terms,and determines the optimal renormalization scale at each order.Our analysis shows that a more accurate free energy density up to gs^5-order level without renormalization scale dependence can be achieved by applying the PMC.We also observe that by using a smaller factorization scale around the effective parameter m E,the PMC prediction is consistent with the lattice QCD prediction derived at low temperature.