The production of the three normal neutrinos via e-e+ collision at Z-boson peak(neutrino production in a Z-factory) is investigated thoroughly. The differences of νe-pair production from νμ-pair and ντ-pair produ...The production of the three normal neutrinos via e-e+ collision at Z-boson peak(neutrino production in a Z-factory) is investigated thoroughly. The differences of νe-pair production from νμ-pair and ντ-pair production are presented in various aspects. Namely the total cross sections, relevant differential cross sections and the forwardbackward asymmetry etc. for these neutrinos are presented in terms of figures as well as numerical tables. The restriction on the room for the mixing of the three species of light neutrinos with possible externals(heavy neutral leptons and/or sterile neutrinos) from refined measurements of the invisible width of Z-boson is discussed.展开更多
We present a comprehensive analytic calculation of the next-to-next-to-leading order QCD■EW corrections to Z-boson pair production at electron-positron colliders.The two-loop master integrals essential to this calcul...We present a comprehensive analytic calculation of the next-to-next-to-leading order QCD■EW corrections to Z-boson pair production at electron-positron colliders.The two-loop master integrals essential to this calculation are evaluated using the differential equation method.In this paper,we detail the formulation and solution of the canonical differential equations for the two-loop three-point master integrals with two on-shell Z-boson external legs and a massive internal quark in the loops.These canonical master integrals are systematically expanded as a Taylor series in the dimensional regulator,ε=(4-d)/2,up to the order of ε^(4),with coefficients expressed in terms of Goncharov polylogarithms up to weight four.Upon applying our analytic expressions of these master integrals to the phenomenological analysis of Z-pair production,we observe that the O(aa_(s))corrections manifest at a level of approximately one percent when compared to the leading-order predictions,underscoring their significance for comparisons with future high-precision experimental data.展开更多
Within the standard model,we have investigated rare Z-boson decays into double heavy quarkonia,Z→VV and Z→VP,with V and P denoting vector and pseudo scalar quarkonia,respectively.It is assumed that the leading-order...Within the standard model,we have investigated rare Z-boson decays into double heavy quarkonia,Z→VV and Z→VP,with V and P denoting vector and pseudo scalar quarkonia,respectively.It is assumed that the leading-order QCD diagrams would give the dominant contributions to these processes,and the corresponding branching fractions,for instance,B(Z→J/ΨJ/Ψ),have been estimated to be approximately 10^(-13)in literature.However,these decays could also happen through electromagnetic transitions Z→Vγ^(*)and Z→Pγ^(*),with the virtual photon transforming into V.Interestingly,the smallness of the vector quarkonium mass can give rise to a large factor m_(Z)^(2)/m_(V)^(2)relative to the QCD contributions,which thus counteracts the suppression from the electromagnetic coupling.We systematically include these two types of contributions in our calculation to predict branching fractions for these decays.Particularly,owing to the virtual photon effects,it is found that B(Z→J/ΨJ/Ψ)will be significantly enhanced,up to 10^(-10).展开更多
Z-boson decay provides a good opportunity to search for theΞbQ baryon because a large number of its events can be collected at high energy colliders.In this paper,we perform a complete investigation of the indirect p...Z-boson decay provides a good opportunity to search for theΞbQ baryon because a large number of its events can be collected at high energy colliders.In this paper,we perform a complete investigation of the indirect production of theΞbc andΞbb baryons via the Z-boson decay process Z→Ξbo+b+Q with a Q=(c,b)quark under the NRQCD factorization approach.After considering the contibution from the diquark states(be)PSil3/6,<bc)[^(1)Sol3/6,(bb)[^(3)Sol6,and(bb)[3S1l3,the calculated branching fractions are B(Z-→Ξbe+X)=3.595×10^(-5)and B(Z→Ξbb+X)=1.213×10^(-6).Furthermore,theΞbe andΞbb production events are predicted to be of the order of 104 and 103 at the LHC collider,and the order of 107 and 106 for the CEPC collider.We then estimate the produc tion ratio for Z→c2(bb)→Ξbc+X withΞbc→Λ^(+)_(c)in Z-boson decay,that is,R(Z→cc→Ξ0bc+X)~0(10^(-6))br and R(Z→bb→Ξbc+X)~0(10^(-5)),respectively.Finally,we present the differential decay widths ofΞbc andΞbb with respect to 823 and z distributions and analyze the uncertainties.展开更多
The understanding of the mechanism for the mass building of elementary particles of Standard Model (SM) has made significant progresses since the confirmation of the existence of the Higgs boson, in particular the rea...The understanding of the mechanism for the mass building of elementary particles of Standard Model (SM) has made significant progresses since the confirmation of the existence of the Higgs boson, in particular the realization that the mass of an elementary particle of SM is not “God-given” but is created by interactions with involved energy fields. Nevertheless, a sophisticated model to answer fundamental questions is still missing. Further research is needed to compensate for the existing deficit. The current paper is aimed to contribute to such research by using “harmonic quark series”. Harmonic quark series were introduced between 2003 and 2005 by O. A. Teplov and represented a relatively new approach to understanding the physical masses of elementary particles. Although they are not generally recognized, some research works have revealed very interesting and exciting facts regarding the mass quanta. The original harmonic quark series consists of mathematical “quark” entities with an energy-mass quantum between 7.87 MeV and 69.2 GeV. They obey a strict mathematical rule derived from the general harmonic oscillation theory. Teplov showed some quantitative relations between the masses of his harmonic quarks and the SM particles, especially in the intermediate mass range, i.e. mesons and hadrons up to 1000 MeV. Early research work also includes the investigation of H. Yang/W. Yang in the development of their so-called YY model for elementary particles (Ying-Yang model with “Ying” and “Yang” as quark components for a new theoretical particle framework). Based on Teplov’s scheme and its mathematical formula, they introduced further harmonic quarks down to 1 eV and showed some quantitative relationships between the masses of these harmonic quarks and the masses of electrons and up and down quarks. In this article, we will extend the harmonic quark series according to the Teplov scheme up to a new entity with a mass quantum of 253.4 GeV and show some interesting new mass relations to the heavy particles of the Standard Model (W boson, Z boson, top quark and Higgs boson). Based on these facts, some predictions will be made for experimental verification. We also hope that our investigation and result will motivate more researcher to dedicate their work to harmonic quark series in theory and in experiments.展开更多
The fine-structure constant (α) at low and high energies is herein computed from control numbers in the theory of the golden section (φ). Countless attempts at deriving, or otherwise explaining the origin of αhave ...The fine-structure constant (α) at low and high energies is herein computed from control numbers in the theory of the golden section (φ). Countless attempts at deriving, or otherwise explaining the origin of αhave so far focused and somewhat succeeded on αat low energy. This manuscript, therefore, provides a more complete solution. That αpermeates even the golden section is not only further confirmation of the ubiquity of this constant of physics, but also leads to the inescapable conclusion that it originates in the golden section, a geometrical constant ubiquitous in physical phenomena.展开更多
The Harmonic Neutron Hypothesis, HNH, has demonstrated that many of the fundamental physical constants including particles and bosons are associated with specific quantum integers, n. These integers define partial har...The Harmonic Neutron Hypothesis, HNH, has demonstrated that many of the fundamental physical constants including particles and bosons are associated with specific quantum integers, n. These integers define partial harmonic fractional exponents, 1 ± (1/n), of a fundamental frequency, Vf. The goal is to evaluate the prime and composite factors associated with the neutron n0, the quarks, the kinetic energy of neutron beta decay, the Rydberg constant, R, e, a0, H0, h, α, W, Z, the muon, and the neutron gluon. Their pure number characteristics correspond and explain the hierarchy of the particles and bosons. The elements and black body radiation represent consecutive integer series. The relative scale of the constants cluster in a partial harmonic fraction pattern around the neutron. The global numerical organization is related to the only possible prime factor partial fractions of 2/3, or 3/2, as pairs of 3 physical entities with a total of 6 in each group. Many other progressively resonant prime number factor patterns are identified with increasing numbers of smaller factors, higher primes, or larger partial fractions associated with higher order particles or bosons.展开更多
为了研究LHCb 7 TeV W+、W-和Z实验数据对CT14HERA2部分子分布函数(Parton Distribution Functions,PDFs)的影响,首先将收集到的数据进行了理论预测并将其和实验测量结果进行了比较,在误差允许的范围内理论和实验符合的很好。其次,用误...为了研究LHCb 7 TeV W+、W-和Z实验数据对CT14HERA2部分子分布函数(Parton Distribution Functions,PDFs)的影响,首先将收集到的数据进行了理论预测并将其和实验测量结果进行了比较,在误差允许的范围内理论和实验符合的很好。其次,用误差PDFs更新软件包(Error PDFs Updated Method Package,EPUMP)更新了CT14HERA2 PDFs,并和全局拟合的PDFs进行了比较。最后,加入协方差矩阵后的实验数据可以在较大和较小的x区域减少d(x,Q)/u(x,Q)误差,同时也对CT14HERA2 PDFs进行了优化。验证结果表明,LHCb 7 TeV W+、W-和Z产生的实验数据在较大的x区域对g(x,Q)、d(x,Q)、d(x,Q)/u(x,Q)、d(x,Q)/u(x,Q)、u(x,Q)、d(x,Q)和u(x,Q)PDFs的中心值约束较大,可以用前4个误差PDFs代替原来全局拟合或优化后得到的56个误差集。展开更多
The present article develops a model initially published in ref. [1]. It is a quasi-classical quantum model of composite particles with ultra-relativistic (UR) constituents (leptons and quarks). The model is used to c...The present article develops a model initially published in ref. [1]. It is a quasi-classical quantum model of composite particles with ultra-relativistic (UR) constituents (leptons and quarks). The model is used to calculate the mass energy of three composite particles: a UR tauonium, a UR bottomonium and a UR leptoquarkonium. The result is that these three hypothetic particles have masses close to 125 GeV: the Higgs boson mass energy. These results are recalled in the present article. Then the model is extended to calculate the mass energy of <i>pi</i>-mesons, <i>W</i> and <i>Z</i> bosons. Finally, the model provides a hypothesis on dark matter.展开更多
The massive vector bosons Z o, W ± and the scalar Higgs-boson H o assumed in weak interaction theory, but also the six quarks required in strong interactions are well understood in an alternative quantum field th...The massive vector bosons Z o, W ± and the scalar Higgs-boson H o assumed in weak interaction theory, but also the six quarks required in strong interactions are well understood in an alternative quantum field theory of fermions and bosons: Z o and W ± as well as all quark-antiquark states (here only the tt¯state is discussed) are described by bound states with scalar coupling between their massless constituents and have a structure similar to leptons. However, the scalar Higgs-boson H o corresponds to a state with vector coupling between the elementary constituents. Similar scalar states are expected also in the mass region of the mesons ω (0.782 GeV) - Υ ( 9.46 GeV). The underlying calculations can be run on line using the Web-address https://h2909473.stratoserver.net.展开更多
Using Breit-Wigner resonance relation, bounds on the magnetic moment of the tau-neutrino are calculated through the reaction e^＋e^- →vv^-y at the neutral boson pole in the framework of a superstringinspired E6 model...Using Breit-Wigner resonance relation, bounds on the magnetic moment of the tau-neutrino are calculated through the reaction e^＋e^- →vv^-y at the neutral boson pole in the framework of a superstringinspired E6 model which has one extra low-energy neutral gauge boson and a LRSM.展开更多
本文介绍了LHCb实验中的两项重要研究,旨在以电弱相互作用玻色子为工具探索原子核中的部分子分布函数(nuclear parton distribution functions,n PDFs).第一项研究利用质子-铅核对撞数据测量了Z玻色子的产生,用Z玻色子作为探针研究量子...本文介绍了LHCb实验中的两项重要研究,旨在以电弱相互作用玻色子为工具探索原子核中的部分子分布函数(nuclear parton distribution functions,n PDFs).第一项研究利用质子-铅核对撞数据测量了Z玻色子的产生,用Z玻色子作为探针研究量子色动力学(quantum chromodynamics,QCD)和nPDFs.通过测量Z玻色子的产生截面,研究人员可以更准确地确定和理解部分子在核物质环境中的分布,从而完善现有的QCD理论并提高nPDFs的精度.第二项研究在铅核-铅核超周边对撞中研究了J/ψ和ψ(2S)介子的光致产生.这种对撞中,两个铅核通过光子和核内胶子的相互作用产生粲夸克偶素.相干光致产生涉及光子与整个原子核的胶子相互作用,能量交换较小,原子核保持完整.该研究验证了现有的微扰QCD和胶子交换模型,并提供了关于核遮蔽效应和核内胶子分布的重要信息.LHCb实验首次测量了粲夸克偶素随横动量变化的相干光致产生截面,并观测到了衍射效应,为未来高能核物理研究提供了宝贵数据.展开更多
The hitherto unconstrained lepton flavor mixings,induced by the new gauge boson Z ,which are the prediction of many new physics models,such as topcolor-assisted technicolor (TC2) models and flavor-universal TC2 models...The hitherto unconstrained lepton flavor mixings,induced by the new gauge boson Z ,which are the prediction of many new physics models,such as topcolor-assisted technicolor (TC2) models and flavor-universal TC2 models,may lead to the lepton flavor violating productions of τμˉ,τeˉ and μeˉ in photon-photon collision at the proposed International Linear Collider (ILC).Through a comparative analysis of these processes,we find that the better channel to probe the new physics models is the production of τμˉ or τeˉ which occurs at a much higher rate than μeˉ production due to the large mixing angle and the large flavor changing coupling,and may reach the detectable level of the ILC for a large part of the parameter space.Since the rates predicted by the Standard Model are far below the detectable level,these processes may serve as a sensitive probe for such new physics models.展开更多
We examine various direct and indirect constraints on the lepton-specific two-Higgs doublet model and discuss its phenomenology at colliders in the allowed parameter space.The constraints we consider come from the pre...We examine various direct and indirect constraints on the lepton-specific two-Higgs doublet model and discuss its phenomenology at colliders in the allowed parameter space.The constraints we consider come from the precision electroweak data,the direct search for Higgs boson,the muon anomalous magnetic moment,as well as some theoretical consistency requirements.We find that in the allowed parameter space the CP-odd Higgs boson A is rather light (m A 【 30 GeV with 95% possibility),which is composed dominantly by the leptonic Higgs and decays dominantly into τ + τ;while the SM-like Higgs boson h (responsible largely for electroweak symmetry breaking) decays dominantly in the mode h → AA → 4τ with a large decay width,which will make the Higgs discovery more difficult at the LHC.Whereas,this scenario predicts rare Z decays Z → AAA and Z →τ + τA with their branching ratios ranging from 10-8 to 10-and 10-5 to 10-4 respectively,which may be accessible at the GigaZ option of the ILC.展开更多
基金Supported by the National Natural Science Foundation of China(NNSFC) under Grant Nos.11275243,11147001,11275036,11047002,11205227the open project of State Key Laboratory of Theoretical Physics under Grant No.Y3KF311CJ1+1 种基金the Natural Science Foundation of Hebei province under Grant No.A2013201277Natural Science Foundation of Hebei University under Grant Nos.2011JQ05,2012-242.1
文摘The production of the three normal neutrinos via e-e+ collision at Z-boson peak(neutrino production in a Z-factory) is investigated thoroughly. The differences of νe-pair production from νμ-pair and ντ-pair production are presented in various aspects. Namely the total cross sections, relevant differential cross sections and the forwardbackward asymmetry etc. for these neutrinos are presented in terms of figures as well as numerical tables. The restriction on the room for the mixing of the three species of light neutrinos with possible externals(heavy neutral leptons and/or sterile neutrinos) from refined measurements of the invisible width of Z-boson is discussed.
基金Supported by the National Natural Science Foundation of China(12061141005)the CAS Center for Excellence in Particle Physics(CCEPP)。
文摘We present a comprehensive analytic calculation of the next-to-next-to-leading order QCD■EW corrections to Z-boson pair production at electron-positron colliders.The two-loop master integrals essential to this calculation are evaluated using the differential equation method.In this paper,we detail the formulation and solution of the canonical differential equations for the two-loop three-point master integrals with two on-shell Z-boson external legs and a massive internal quark in the loops.These canonical master integrals are systematically expanded as a Taylor series in the dimensional regulator,ε=(4-d)/2,up to the order of ε^(4),with coefficients expressed in terms of Goncharov polylogarithms up to weight four.Upon applying our analytic expressions of these master integrals to the phenomenological analysis of Z-pair production,we observe that the O(aa_(s))corrections manifest at a level of approximately one percent when compared to the leading-order predictions,underscoring their significance for comparisons with future high-precision experimental data.
基金Supported in part by the National Natural Science Foundation of China(11575175,12047502)National Research and development Program of China(2020YFA0406400)。
文摘Within the standard model,we have investigated rare Z-boson decays into double heavy quarkonia,Z→VV and Z→VP,with V and P denoting vector and pseudo scalar quarkonia,respectively.It is assumed that the leading-order QCD diagrams would give the dominant contributions to these processes,and the corresponding branching fractions,for instance,B(Z→J/ΨJ/Ψ),have been estimated to be approximately 10^(-13)in literature.However,these decays could also happen through electromagnetic transitions Z→Vγ^(*)and Z→Pγ^(*),with the virtual photon transforming into V.Interestingly,the smallness of the vector quarkonium mass can give rise to a large factor m_(Z)^(2)/m_(V)^(2)relative to the QCD contributions,which thus counteracts the suppression from the electromagnetic coupling.We systematically include these two types of contributions in our calculation to predict branching fractions for these decays.Particularly,owing to the virtual photon effects,it is found that B(Z→J/ΨJ/Ψ)will be significantly enhanced,up to 10^(-10).
基金Supported in part by the Natural Science Foundation of China (12265010)the Project of Guizhou Provincial Department of Education (KY[2021]030)
文摘Z-boson decay provides a good opportunity to search for theΞbQ baryon because a large number of its events can be collected at high energy colliders.In this paper,we perform a complete investigation of the indirect production of theΞbc andΞbb baryons via the Z-boson decay process Z→Ξbo+b+Q with a Q=(c,b)quark under the NRQCD factorization approach.After considering the contibution from the diquark states(be)PSil3/6,<bc)[^(1)Sol3/6,(bb)[^(3)Sol6,and(bb)[3S1l3,the calculated branching fractions are B(Z-→Ξbe+X)=3.595×10^(-5)and B(Z→Ξbb+X)=1.213×10^(-6).Furthermore,theΞbe andΞbb production events are predicted to be of the order of 104 and 103 at the LHC collider,and the order of 107 and 106 for the CEPC collider.We then estimate the produc tion ratio for Z→c2(bb)→Ξbc+X withΞbc→Λ^(+)_(c)in Z-boson decay,that is,R(Z→cc→Ξ0bc+X)~0(10^(-6))br and R(Z→bb→Ξbc+X)~0(10^(-5)),respectively.Finally,we present the differential decay widths ofΞbc andΞbb with respect to 823 and z distributions and analyze the uncertainties.
文摘The understanding of the mechanism for the mass building of elementary particles of Standard Model (SM) has made significant progresses since the confirmation of the existence of the Higgs boson, in particular the realization that the mass of an elementary particle of SM is not “God-given” but is created by interactions with involved energy fields. Nevertheless, a sophisticated model to answer fundamental questions is still missing. Further research is needed to compensate for the existing deficit. The current paper is aimed to contribute to such research by using “harmonic quark series”. Harmonic quark series were introduced between 2003 and 2005 by O. A. Teplov and represented a relatively new approach to understanding the physical masses of elementary particles. Although they are not generally recognized, some research works have revealed very interesting and exciting facts regarding the mass quanta. The original harmonic quark series consists of mathematical “quark” entities with an energy-mass quantum between 7.87 MeV and 69.2 GeV. They obey a strict mathematical rule derived from the general harmonic oscillation theory. Teplov showed some quantitative relations between the masses of his harmonic quarks and the SM particles, especially in the intermediate mass range, i.e. mesons and hadrons up to 1000 MeV. Early research work also includes the investigation of H. Yang/W. Yang in the development of their so-called YY model for elementary particles (Ying-Yang model with “Ying” and “Yang” as quark components for a new theoretical particle framework). Based on Teplov’s scheme and its mathematical formula, they introduced further harmonic quarks down to 1 eV and showed some quantitative relationships between the masses of these harmonic quarks and the masses of electrons and up and down quarks. In this article, we will extend the harmonic quark series according to the Teplov scheme up to a new entity with a mass quantum of 253.4 GeV and show some interesting new mass relations to the heavy particles of the Standard Model (W boson, Z boson, top quark and Higgs boson). Based on these facts, some predictions will be made for experimental verification. We also hope that our investigation and result will motivate more researcher to dedicate their work to harmonic quark series in theory and in experiments.
文摘The fine-structure constant (α) at low and high energies is herein computed from control numbers in the theory of the golden section (φ). Countless attempts at deriving, or otherwise explaining the origin of αhave so far focused and somewhat succeeded on αat low energy. This manuscript, therefore, provides a more complete solution. That αpermeates even the golden section is not only further confirmation of the ubiquity of this constant of physics, but also leads to the inescapable conclusion that it originates in the golden section, a geometrical constant ubiquitous in physical phenomena.
文摘The Harmonic Neutron Hypothesis, HNH, has demonstrated that many of the fundamental physical constants including particles and bosons are associated with specific quantum integers, n. These integers define partial harmonic fractional exponents, 1 ± (1/n), of a fundamental frequency, Vf. The goal is to evaluate the prime and composite factors associated with the neutron n0, the quarks, the kinetic energy of neutron beta decay, the Rydberg constant, R, e, a0, H0, h, α, W, Z, the muon, and the neutron gluon. Their pure number characteristics correspond and explain the hierarchy of the particles and bosons. The elements and black body radiation represent consecutive integer series. The relative scale of the constants cluster in a partial harmonic fraction pattern around the neutron. The global numerical organization is related to the only possible prime factor partial fractions of 2/3, or 3/2, as pairs of 3 physical entities with a total of 6 in each group. Many other progressively resonant prime number factor patterns are identified with increasing numbers of smaller factors, higher primes, or larger partial fractions associated with higher order particles or bosons.
文摘为了研究LHCb 7 TeV W+、W-和Z实验数据对CT14HERA2部分子分布函数(Parton Distribution Functions,PDFs)的影响,首先将收集到的数据进行了理论预测并将其和实验测量结果进行了比较,在误差允许的范围内理论和实验符合的很好。其次,用误差PDFs更新软件包(Error PDFs Updated Method Package,EPUMP)更新了CT14HERA2 PDFs,并和全局拟合的PDFs进行了比较。最后,加入协方差矩阵后的实验数据可以在较大和较小的x区域减少d(x,Q)/u(x,Q)误差,同时也对CT14HERA2 PDFs进行了优化。验证结果表明,LHCb 7 TeV W+、W-和Z产生的实验数据在较大的x区域对g(x,Q)、d(x,Q)、d(x,Q)/u(x,Q)、d(x,Q)/u(x,Q)、u(x,Q)、d(x,Q)和u(x,Q)PDFs的中心值约束较大,可以用前4个误差PDFs代替原来全局拟合或优化后得到的56个误差集。
文摘The present article develops a model initially published in ref. [1]. It is a quasi-classical quantum model of composite particles with ultra-relativistic (UR) constituents (leptons and quarks). The model is used to calculate the mass energy of three composite particles: a UR tauonium, a UR bottomonium and a UR leptoquarkonium. The result is that these three hypothetic particles have masses close to 125 GeV: the Higgs boson mass energy. These results are recalled in the present article. Then the model is extended to calculate the mass energy of <i>pi</i>-mesons, <i>W</i> and <i>Z</i> bosons. Finally, the model provides a hypothesis on dark matter.
文摘The massive vector bosons Z o, W ± and the scalar Higgs-boson H o assumed in weak interaction theory, but also the six quarks required in strong interactions are well understood in an alternative quantum field theory of fermions and bosons: Z o and W ± as well as all quark-antiquark states (here only the tt¯state is discussed) are described by bound states with scalar coupling between their massless constituents and have a structure similar to leptons. However, the scalar Higgs-boson H o corresponds to a state with vector coupling between the elementary constituents. Similar scalar states are expected also in the mass region of the mesons ω (0.782 GeV) - Υ ( 9.46 GeV). The underlying calculations can be run on line using the Web-address https://h2909473.stratoserver.net.
文摘Using Breit-Wigner resonance relation, bounds on the magnetic moment of the tau-neutrino are calculated through the reaction e^＋e^- →vv^-y at the neutral boson pole in the framework of a superstringinspired E6 model which has one extra low-energy neutral gauge boson and a LRSM.
文摘本文介绍了LHCb实验中的两项重要研究,旨在以电弱相互作用玻色子为工具探索原子核中的部分子分布函数(nuclear parton distribution functions,n PDFs).第一项研究利用质子-铅核对撞数据测量了Z玻色子的产生,用Z玻色子作为探针研究量子色动力学(quantum chromodynamics,QCD)和nPDFs.通过测量Z玻色子的产生截面,研究人员可以更准确地确定和理解部分子在核物质环境中的分布,从而完善现有的QCD理论并提高nPDFs的精度.第二项研究在铅核-铅核超周边对撞中研究了J/ψ和ψ(2S)介子的光致产生.这种对撞中,两个铅核通过光子和核内胶子的相互作用产生粲夸克偶素.相干光致产生涉及光子与整个原子核的胶子相互作用,能量交换较小,原子核保持完整.该研究验证了现有的微扰QCD和胶子交换模型,并提供了关于核遮蔽效应和核内胶子分布的重要信息.LHCb实验首次测量了粲夸克偶素随横动量变化的相干光致产生截面,并观测到了衍射效应,为未来高能核物理研究提供了宝贵数据.
文摘The hitherto unconstrained lepton flavor mixings,induced by the new gauge boson Z ,which are the prediction of many new physics models,such as topcolor-assisted technicolor (TC2) models and flavor-universal TC2 models,may lead to the lepton flavor violating productions of τμˉ,τeˉ and μeˉ in photon-photon collision at the proposed International Linear Collider (ILC).Through a comparative analysis of these processes,we find that the better channel to probe the new physics models is the production of τμˉ or τeˉ which occurs at a much higher rate than μeˉ production due to the large mixing angle and the large flavor changing coupling,and may reach the detectable level of the ILC for a large part of the parameter space.Since the rates predicted by the Standard Model are far below the detectable level,these processes may serve as a sensitive probe for such new physics models.
基金supported in part by the National Natural Science Foundation of China (NNSFC) (Grant Nos.10505007,10821504,10725526 and 10635030)HASTIT (Grant No.2009HASTIT004)the Project of Knowledge Innovation Program (PKIP) of Chinese Academy of Sciences (Grant No.KJCX2.YW.W10)
文摘We examine various direct and indirect constraints on the lepton-specific two-Higgs doublet model and discuss its phenomenology at colliders in the allowed parameter space.The constraints we consider come from the precision electroweak data,the direct search for Higgs boson,the muon anomalous magnetic moment,as well as some theoretical consistency requirements.We find that in the allowed parameter space the CP-odd Higgs boson A is rather light (m A 【 30 GeV with 95% possibility),which is composed dominantly by the leptonic Higgs and decays dominantly into τ + τ;while the SM-like Higgs boson h (responsible largely for electroweak symmetry breaking) decays dominantly in the mode h → AA → 4τ with a large decay width,which will make the Higgs discovery more difficult at the LHC.Whereas,this scenario predicts rare Z decays Z → AAA and Z →τ + τA with their branching ratios ranging from 10-8 to 10-and 10-5 to 10-4 respectively,which may be accessible at the GigaZ option of the ILC.
