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Experimental sensitivity on searching for cp violation at BES-Ⅲ

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Chinese Physics B 2009年第6期18卷 2213-2216页

作者：赵明刚荣刚马海龙张达华 Institute of High Energy Physics Chinese Academy of Sciences

The cp violation in the D system is predicted to be an unobserved level in the Standard Model. In this paper, we describe the method of searching for cp violation decay processes with the coherently produced D^0D^0 mesons from the ψ（3770） decay. The cp violation decay processes can be searched for at the BES-Ⅲ experiment. The experimental sensitivity for searching for the cp violation can reach about a 10^-4 level with a ψ（3770） data sample of about 20 fb^-1.

关键词： cp violation charm meson BES-Ⅲ

Measurements of D^0-~0 mixing and searches for cp violation:HFAG combination of all data

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Chinese Physics C 2008年第6期32卷 477-482页

作者： A.J.Schwartz Physics Department University of CincinnatiCincinnatiOhio 45221USA

We present world average values for D^0-D^0 mixing parameters x and y, cp violation parameters ｜q/P｜ and Arg（q/p）, and strong phase differences δ and δKππ. These values are calculated by the Heavy Flavor Averaging Group （HFAG） by performing a global fit to relevant experimental measurements. The results for x and y differ significantly from zero and are inconsistent with no mixing at the level of 6.7a. The results for ｜q/P｜ and Arg（q/p） are consistent with no cp violation. The strong phase difference δ is less than 45° at 95% C.L.

关键词： mixing cp violation

Measuring cp violation in rare W decays at the LHC

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Chinese Physics C 2022年第10期46卷 107-115页

作者：路鹏程司宗国王喆杨兴华 School of Physics Shandong UniversityJinan 250100China School of Physics and Optoelectronic Engineering Shandong University of TechnologyZibo 255000China

Heavy Majorana neutrinos beyond the standard model can simultaneously explain the origin of tiny neutRino masses and matter-antimatter asymmetry in our Universe.The existence of heavy Majorana neutrinos will also lead to lepton number violation and confirm the possibility of rare lepton-number-violating W decays.With contributions from two different Majorana neutrinos,nonzero cp asymmetry may be generated from the rate difference between W decay and its cp-conjugate process.The aim of this study is to investigate the prospects of measuring cp violation in rare w decays via Majorana neutRInos at the LHC.Our calculations show that the induced cp asymmetry is independent of the Majorana neutrino mass for 15cp asymmetry,if observed,would in turn provide unambiguous evidence of new physics beyond the standard model.

关键词： lepton number violation W decay Majorana cp violation

Implications of the Daya Bay observation of θ_(13) on the leptonic flavor mixing structure and cp violation

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Chinese Physics C 2012年第4期36卷 281-297页

作者：邢志忠 Institute of High Energy Physics Chinese Academy of Sciences

The Daya Bay collaboration has recently reported its first νe → νe oscillation result which points to θ13 8.8 ± 0.8 （best-fit ±1σ range） or θ13 = 0 at the 5.2σ level. The fact that this smallest neutrino mixing angle is not strongly suppressed motivates us to look into the underlying structure of lepton flavor mixing and cp violation. Two phenomenological strategies are outlined：（1） the lepton flavor mixing matrix U consists of a constant leading term U0 and a small perturbation term U ; and （2） the mixing angles of U are associated with the lepton mass ratios. Some typical patterns of U0 are reexamined by constraining their respective perturbations with current experimental data. We illustrate a few possible ways to minimally correct U0 in order to fit the observed values of three mixing angles. We point out that the structure of U may exhibit an approximate μ-τ permutation symmetry in modulus, and reiterate the geometrical description of cp violation in terms of the leptonic unitarity triangles. The salient features of nine distinct parametrizations of U are summarized, and its Wolfenstein-like expansion is presented by taking U0 to be the democratic mixing pattern.

关键词： the Daya Bay experiment theta（13） lepton flavor mixing cp violation

D^0 -~0 mixing and cp violation at BES-Ⅲ

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Chinese Physics C 2008年第6期32卷 470-476页

作者：李海波 Institute of High Energy Physics CAS

Recently, both BaBar and Belle experiments found evidences of neutral D mixing. In this paper, we discuss the sensitivities of the measurements of D mixing parameters at BES-Ⅲ. With cp tag technique at ψ（3770） peak, the extraction of the strong phase difference in D^0 → Kπ decay at BES-Ⅲ are discussed. We also make an estimate on the measurements of the mixing rate RM by using the coherent data at ψ（3770） peak. The cp violation in D system is predicted with an unobserved level in the Standard Model. Any significant cp violation in the D system indicates the existence of new physics. The sensitivity of the measurements of cp violation in the D system is estimated in the coherent D decays. Finally, the search for the rare D decays are discussed, in which some of the forbidden decays are smoking gun of new physics.

关键词： D mixing BES-Ⅲ experiment cp violation rare decay

Direct cp violation in B_(s) → J/ψP(V)

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Chinese Physics C 2012年第7期36卷 585-591页

作者：吕刚刘豪郭新恒 College of Science Henan University of Technology College of Nuclear Science and Technology Beijing Normal University

In the framework of factorization, we study direct cp violation in the decays of B（s） → J/φP（V）（P（V） refer to the pseudoscalar （vector） meson）. The cp violation depends strongly on Cabibbo-Kobayashi- Maskawa （CKM） matrix elements and the effective parameter, Nc. The recent experimental data for the branching ratios of B（s） → J/φP（V） are accurate enough and we can give a strong constraint on the range of Arc. We find that the cp violating asymmetry is consistent with the available experiment values for the b→ d transition, and a little smaller than the b→ s transition. We also predict the cp violation of other decay channels for B（s） → J/φP（V）. We expect our results can give valuable guidance for experiments.

关键词： branching ratio Nc cp violation

Prospects of cp violation inΛdecay with a polarized electron beam at the STCF

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Chinese Physics C 2023年第11期47卷 1-6页

作者：曾胜徐月周小蓉秦佳佳郑波 University of South China Hengyang 421001China Department of Physics Liaoning UniversityShenyang 110036China School of Physical Sciences University of Science and Technology of ChinaHefei 230026China

Based on 1.89×10^(8) J/ψ→ΛΛ Monte Carlo(MC)events produced from a longitudinally-polarized electron beam,the sensitivity of the cp violation of A decay is studied using fast simulation software.In addition,the J/ψ→ΛΛ decay can be used to optimize the detector response using the interface provided by the fast simulation software.In the future,the STCF is expected to obtain 3.4 trillion J/ψevents,and the statistical sensitivity of the cp violation of A decay via the J/ψ→ΛΛ process is expected to reach O(10^(-5))when the electron beam polarization is 80%.

关键词： cp violation electron beam polarized STCF

Exploring HVV amplitudes with cp violation using decomposition and the on-shell scattering amplitude method

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Chinese Physics C 2023年第3期47卷 67-83页

作者：冯柯尧万霞王由凯邬超 School of Physics and Information Technology Shaanxi Normal UniversityXi'an 710119China CAS Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academey of SciencesBeijing 100190China

cp violation may play an important role in baryogenesis in the early universe and should be examined comprehensively at colliders.We study the cp properties of HVV vertexes between Higgs and gauge boson pairs by defining a cp violation phase angle,which indicates the mixture of cp-even and cp-odd Higgs states in HVV in new physics.A series of HVV amplitudes,H→γγ,H-→V→γtt,and H→VV-→4f,with a cp phase angle are studied systematically to explicitly explain why cp violation can only be probed independently in the 4t pro-cess.We obtain a novel amplitude decomposition relation that illustrates that if two preconditions(multilinear mo-mentum dependent vertexes,and the current J_(μ) of V→l^(+)l^(-)is formally proportional to a photon's polarization vec-tor)are satisfied,a higher-point amplitude can be decomposed into a summation of a series of lower-point amp-litudes.As a practical example,the amplitude of the H→γV-→γtt and H→VV→4t processes can be decom-posed into a summation of many H→γγ amplitudes.We calculate these amplitudes in the framework of the on-shell scattering amplitude method,considering both massless and massive vector gauge bosons with the cp viola-tion phase angle.The above two approaches provide consistent results and clearly reveal the cp violation ξ depend-ence in the amplitudes.

关键词： Higgs scattering amplitude cp violation

Studying the localized cp violation and the branching fraction of the B^0→K^-π^+π^+π^-decay

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Chinese Physics C 2020年第10期44卷 51-58页

作者：祁敬娟王振洋徐晶郭新恒 Junior College Zhejiang Wanli UniversityZhejiang 315101China Physics Department Ningbo UniversityZhejiang 315211China Department of Physics Yantai UniversityYantai 264005China College of Nuclear Science and Technology Beijing Normal UniversityBeijing 100875China

In this work,we study the localized cp violation and the branching fraction of the four-body decay^ˉB 0→K^−π^+π^−π^+by employing a quasi-two-body QCD factorization approach.Considering the interference of^ˉB 0→ˉK^∗0(700)ρ0(770)→K^−π^+π^−π^+and^ˉB 0→ˉK∗(892)f0(500)→K^−π^+π^−π^+channels,we predict Acp(^ˉB 0→K^−π^+π^−π^+)∈[0.15,0.28]and B(^ˉB 0→K^−π^+π^−π^+)∈[1.73,5.10]×10^−7,respectively,which shows that the interference mechanism of these two channels can induce the localized cp violation to this four-body decay.Meanwhile,within the two quark model framework for the scalar mesons f0(500)andˉK^∗0(700),we calculate the direct cp violations and branching fractions of the^ˉB 0→ˉK^∗0(700)ρ0(770)and^ˉB 0→ˉK∗(892)f0(500)decays,respectively.The corresponding results are Acp(^ˉB 0→ˉK^∗0(700)ρ0(770))∈[0.20,0.36],Acp(^ˉB 0→ˉK∗(892)f0(500))∈[0.08,0.12],B(^ˉB 0→ˉK^∗0(700)ρ0(770)∈[6.76,18.93]×10^−8 and B(^ˉB 0→ˉK∗(892)f0(500))∈[2.66,4.80]×10^−6,indicating that the cp violations of these two-body decays are both positive and the branching fractions quite different.These studies provide a new way to investigate the aforementioned four-body decay and can be helpful in clarifying the configuration of the structure of the light scalar meson.

关键词： decays of bottom mesons cp violation perturbative calculations