来自HERA的电弱约束

HERA的电弱测量

Electroweak Measurements from HERA

本文介绍HERA轻子质子对撞机实验H1和ZEUS的新的初步电弱结果。这些包括新的高Q^2中性电流截面测量和对可能的夸克半径的限制，在寻找接触相互作用，以及对夸克-Z耦合，提取组合的电弱和QCD拟合。此外，新的带电电流截面测量作为轻子束极化的函数，以及带电电流测量结果，使用合并HERA I数据从H1和ZEUS。最后给出了单个W玻色子产生截面和W玻色子极化分数的测量结果。

HERA的电弱物理

Electroweak Physics at HERA

利用HERA的H1和ZEUS探测器研究了纵向极化轻子束与电子-质子和正电子-质子碰撞中的中性流（NC）和荷电流（CC）深度非弹性散射（DIS）相互作用。极化包容性横截面的测量和比较标准模型（SM）的期望。几个电弱参数的提取使用组合EW-QCD拟合的非极化数据进行了讨论。

HERA电弱参数的测定

A Determination of Electroweak Parameters at HERA

利用已发表的深度非弹性e^+p和e^-p带电和中性电流散射截面，我们进行了电弱和QCD的联合分析，以确定电弱参数与部分子分布的相关性。所使用的数据是由1994-2000年的H1实验收集的，对应的积分亮度为117.2 pb^{-1}。测量了带电电流ep散射中W传播子的质量。弱混合角sin ^2 θ_W在质量壳层重整化方案中确定。HERA首次测量了轻夸克与Z^0玻色子的弱耦合，并研究了右手同位旋分量对弱耦合的可能贡献。

H1和ZEUS实验的最新电弱测量

Recent Electroweak Measurements from the H1 and ZEUS Experiments

Neutral-current ({NC}) and charged-current ({CC}) deep inelastic scattering ({DIS}) reactions have been studied in $e^+p$ and $e^-p$ collisions using the {H1} and {ZEUS} detectors at {HERA I}. Following the upgrade of the {HERA} accelerator, the {HERA II} program recently started with the first data in $e^+p$ scattering with longitudinally polarised positrons. In this paper, a summary of the electroweak results from {HERA I} and the first measurement of the cross section for $e^+p$ CC {DIS} at a longitudinal polarisation value of 33% from the {ZEUS} collaboration are presented.

Electroweak Results from HERA

Neutral and charged current deep inelastic ep scattering with longitudinally polarised lepton beams has been studied with the H1 and ZEUS detectors at HERA. The differential cross sections were measured in the range of four-momentum transfer squared, Q^2, up to 50'000 GeV^2, where electroweak effects become clearly visible. The measurements were used to determine the structure function xF_3 and to constrain vector and the axial-vector couplings of the light quarks to the Z^0 boson. The polarisation dependence of the charged current total cross section was also measured. Limits on flavour chang…

Combined Electroweak and QCD Fit to HERA Data

A simultaneous Electroweak and QCD fit of electroweak parameters and parton distribution functions to HERA data on deep inelastic scattering is presented. The input data are neutral current and charged current inclusive cross sections measured by the H1 and ZEUS collaborations at the ep collider HERA. The polarisation of the electron beam was taken into account for the ZEUS and H1 data recorded between 2004 and 2007. Results are presented on the vector and axial-vector couplings of the Z boson to u- and d-type quarks. The values are in agreement with Standard Model predictions. The results on …

HERA的电弱物理：介绍和总结

Electroweak Physics at HERA: Introduction and Summary

HERA的高光度升级将允许测量标准模型参数和夸克的中性电流耦合。这些结果必须与其他精密测量相一致，或者表明新物理学的痕迹。对$W$生产的分析将补充LEP 2和Tevatron的未来结果。我们总结的主要结果和结论，由工作组对电弱物理有关的潜力，未来的实验在HERA。

在最高Q2和在HERA对撞机的Pt处发生ep碰撞的物理

Physics with ep collisions at highest Q2 and Pt at the HERA collider

HERA对撞机的质心能量为318 GeV，使得研究范围广泛的电弱物理以及寻找标准模型（SM）之外的物理成为可能。本文综述了H1和ZEUS两个对撞机实验的最新结果。包含中性电流和带电电流过程的截面，并从一个组合的电弱和QCD分析的数据进行了讨论。从搜索物理超越SM的选定结果。

HERA上PDF的结构函数及其提取

Structure Functions and Extraction of PDFs at HERA

HERA实验H1和ZEUS对$e^\pm p$深度非弹性散射（DIS）的研究结果为质子结构和QCD的认识提供了重要的贡献。这些数据是在1994-2000年（HERA I）和2003-2006年（HERA II）收集的，1994-1997年的质心能量为$\sqrt{s} = 300$ GeV，1998年为319 GeV。在HERA II期间，轻子束被纵向极化。中性电流（NC）和充电电流（CC）DIS截面HERA II数据的最新结果。讨论了从HERA I数据中提取的部分子密度函数和强耦合$α_s$的结果。考虑到电弱参数与PDF的相关性，在HERA首次进行了电弱和QCD相结合的分析。

Determination of electroweak parameters in polarised deep-inelastic scattering at HERA

The parameters of the electroweak theory are determined in a combined electroweak and QCD analysis using all deep-inelastic $e^+p$ and $e^-p$ neutral current and charged current scattering cross sections published by the H1 Collaboration, including data with longitudinally polarised lepton beams. Various fits to Standard Model parameters in the on-shell scheme are performed. The mass of the $W$ boson is determined as $m(W)=80.520\pm 0.115$ GeV. The axial-vector and vector couplings of the light quarks to the $Z$ boson are also determined. Both results improve the precision of previous H1 deter…

HERA上的高Q2结构函数

High Q2 Structure Functions at HERA

本文介绍了H1和ZEUS关于极化轻子束电弱截面的最新结果，以及由此得到的部分子密度函数的改进。中性电流的截面之间的e-p和e+p的不对称性进行了测量，并显示符合标准模型的宇称破坏。已获得的依赖性的充电电流的截面上的光束极化和其外推到全极化意味着没有右手的充电电流。约束的矢量和轴向矢量耦合的u和d夸克的Z玻色子从一个组合的QCD和电弱拟合和H1和ZEUS数据的组合的结果进行了审查。

实验弱电物理综述

Summary of Expermental Electroweak Physics

在电弱对称性破缺的实验测试的许多方面继续取得进展。介绍了LEP、SLC、Brookhaven g-2环、Tevatron对撞机、HERA、CESR和Tevatron中微子实验的最新情况。也许最令人兴奋的是LEP 2的希格斯粒子搜索，补充了间接约束。然而，只有一个希格斯偶态的标准模型仍然可行。

包括高Q2横截面和QCD和EW在HERA处的配合

Inclusive high Q2 cross sections and QCD and EW fits at HERA

本文介绍了在HERA上用纵向极化轻子束进行的e+/-p碰撞中，中性和带电电流深度非弹性散射截面的最新测量结果。将测量的截面与标准模型的预测值进行比较。下到前导阶QCD分析的HERA数据也。分析产生的质子的部分子分布函数，并扩展到也提取电弱参数。HERA的测定结果与LEP和Tevatron的测定结果进行了比较。

电弱测量

Electroweak Measurements

本文介绍了标准模型电弱扇形的测量结果，包括LEP、Tevatron和HERA对撞机的最新结果。标准模型的鲁棒性说明与精密测量，电弱拟合和从低能量实验获得的结果的比较。研究了$W$玻色子性质的测量现状和碰撞机上涉及弱玻色子的罕见产生过程，以及$ep$碰撞中的电弱参数的测量。

Combined QCD and electroweak analysis of HERA data

A simultaneous fit of parton distribution functions (PDFs) and electroweak parameters to HERA data on deep inelastic scattering is presented. The input data are the neutral current and charged current inclusive cross sections which were previously used in the QCD analysis leading to the HERAPDF2.0 PDFs. In addition, the polarisation of the electron beam was taken into account for the ZEUS data recorded between 2004 and 2007. Results on the vector and axial-vector couplings of the Z boson to u- and d-type quarks, on the value of the electroweak mixing angle and the mass of the W boson are prese…

实验总结

Experimental Summary

总结了在第三十六届Moriond电弱相互作用和统一理论会议上提出的实验结果。结果范围从LEP 2标准模型希格斯玻色子的可能证据到LEP，Tevatron和HERA的新物理搜索，到精确的电弱和弱衰变测量，以及中微子振荡的有力证据。

在HERA上寻找e+p碰撞中的轻子味破坏

Search for lepton-flavor violation in e+p collisions at HERA

利用HERA的ZEUS探测器，在质心能量为300 GeV、积分亮度为47.7 pb^-1的条件下，对轻子味破坏相互作用（e+ p -> mu/tau X）进行了研究。没有发现轻子味违反的证据，并且对可以介导这种相互作用的轻子夸克进行了限制。一些约束也适用于轻子味违反过程介导的方R-宇称违反超对称模型。在某些涉及重夸克的情况下，特别是对于τ通道，ZEUS约束是迄今为止最严格的。

Summary of the Electroweak and Searches Working Group

The working group on electroweak measurements and searches for new physics at the Deep Inelastic Scattering 2012 workshop covered a wide range of results from the various experiments at the LHC (ATLAS, CMS, LHCb), the Tevatron (CDF, DO) and HERA (H1, ZEUS), as well as results from the BaBar, NA48/62 and OPERA collaborations. In addition, invited theoretical overviews were presented and discussed in each of the sessions. A summary of a selection of the results shown at the conference is given.

高Q^2下的电子-质子散射

Electron-Proton Scattering at High Q^2

最近几年HERA记录的$e^{+}p$和$e^{-}p$散射数据为研究高动量转移下$ep$相互作用中的电弱效应提供了可能性，$Q^{2}$，并揭示了Bjorken标度变量x值较大时质子部分子密度的信息。H1和ZEUS从中性流截面测量中提取了广义结构函数$x{\cal F}_{3}$，它与质子的价夸克含量有关。通过对H1中性和带电电流$e^{+}p$和$e^{-}p$数据的全局拟合来提取单个夸克密度。新的结果表明，高$Q^{2}$ $ep$数据的质子结构的敏感性，并指出什么期望从一个1 fb的$^{-1}$数据样本将采取的H1和ZEUS，直到2006年在升级的HERA对撞机。未来的前景有关调查的电弱效应和利用它们来提取质子的部分子含量进行了简短的讨论。

精密电弱测量和对标准模型的约束

Precision Electroweak Measurements and Constraints on the Standard Model

本说明提出了标准模型参数的限制，使用已发表的和初步的精确电弱结果测量的电子-正电子对撞机LEP和SLC。的结果进行了比较，从其他实验中，特别是CDF和DALF在Tevatron精确的电弱测量。对标准模型输入参数的约束来自于高$Q^2$相互作用的结果，并用于预测低$Q^2$实验的结果，如原子宇称破缺、莫勒散射和中微子-核子散射。

从Z共振电弱拟合中提取α_s和对Higgs质量的约束

Extraction of α_s and constraint on the Higgs mass from Electroweak fits at the Z resonance

给出了在LEP1处Z线形参数的测定，并从这些测量中导出了$\alsmz$的值。对希格斯质量的约束，从一个全球性的LEP1和SLC数据拟合得到的。

寻找HERA大Q^2数据的奇异停止解释

Pursuing the Strange Stop Interpretation of the HERA Large Q^2 data

我们探讨了可能的解释的大$Q^2$异常的H1和ZEUS合作报告的停止夸克生产质子中的一个奇怪的夸克通过R-破坏相互作用。这种“奇怪停止”的解释受到LEP测量的$Z \to e^+ e^-$衰变率的限制，以及来自电弱$ρ$参数和CDF和D 0搜索第一代细夸克的限制。我们调查这些约束之间的相互作用，充分考虑停止混合效果。我们发现，如果$m_{\tilde t} \le 200$ GeV只有相对较小的域的电荷子和中性子参数是符合这些限制，并探讨在何种程度上，这种情况下可能会进一步探讨通过搜索接触相互作用在LEP~2和实验与$e^-$和偏振光束在HERA。

精密电弱测量和对标准模型的约束

Precision Electroweak Measurements and Constraints on the Standard Model

本说明提出了标准模型参数的限制，使用已发表的和初步的精确电弱结果测量的电子-正电子对撞机LEP和SLC。的结果进行了比较，从其他实验中，特别是CDF和DALF在Tevatron精确的电弱测量。对标准模型输入参数的约束来自于高$Q^2$相互作用的结果，并用于预测低$Q^2$实验的结果，如原子宇称破缺、莫勒散射和中微子-核子散射。与2007年的实验结果相比，主要的变化是W玻色子质量和宽度以及顶夸克质量的新组合。

Precision Electroweak Measurements and Constraints on the Standard Model

This note presents constraints on Standard Model parameters using published and preliminary precision electroweak results measured at the electron-positron colliders LEP and SLC. The results are compared with precise electroweak measurements from other experiments, notably CDF and DØat the Tevatron. Constraints on the input parameters of the Standard Model are derived from the combined set of results obtained in high-$Q^2$ interactions, and used to predict results in low-$Q^2$ experiments, such as atomic parity violation, Møller scattering, and neutrino-nucleon scattering. The main changes wit…

Precision Electroweak Measurements and Constraints on the Standard Model

This note presents constraints on Standard Model parameters using published and preliminary precision electroweak results obtained at the electron-positron colliders LEP and SLC. The results are compared with precise electroweak measurements from other experiments, notably CDF and DØ at the Tevatron. Constraints on the input parameters of the Standard Model are derived from the combined set of results obtained in high-$Q^2$ interactions, and used to predict results in low-$Q^2$ experiments, such as atomic parity violation, Møller scattering, and neutrino-nucleon scattering. The main changes wi…

初步电弱测量和对标准模型的约束的组合

A Combination of Preliminary Electroweak Measurements and Constraints on the Standard Model

本说明介绍了为2004年夏季会议准备的四个LEP协作和SLD协作的已发表和初步电弱结果的组合。[...]相对于2003年夏天的实验结果的主要变化是更新的W分支分数和四个费米子截面在LEP-2测量，和SLD/LEP重口味的结果在Z极测量。的结果进行了比较，从其他实验中，特别是在中微子-核子散射的NuTeV合作，在铯原子宇称违反的最新结果确定的电弱混合角的最终结果，和测量的电弱混合角的Moller散射与精确的电弱测量。标准模型的参数进行评估，首先使用组合的LEP电弱测量，然后使用全套的高- $Q^2$电弱的结果。

初步电弱测量和对标准模型的约束的组合

A Combination of Preliminary Electroweak Measurements and Constraints on the Standard Model

本说明介绍了为2000年夏季会议准备的四个LEP协作和SLD协作的已发表和初步电弱结果的组合。从Z_0共振结果导出强子和轻子截面、轻子前后不对称性、τ极化不对称性、bbbar和ccbar部分宽度和前后不对称性以及qqbar电荷不对称性。以上的Z 0共振，平均值来自双费米子截面和不对称性，W-对，Z-对和单W生产截面，电弱规范玻色子耦合和W质量和衰变分支比。相对于1999年夏天的结果，主要的变化是LEP的最终Z 0线形结果，LEP的W质量和规范玻色子耦合的更新，以及SLD的ALR。结果进行了比较，从其他实验中精确的电弱测量。标准模型的参数进行评估，首先使用组合的LEP电弱测量，然后使用全套的电弱结果。

Measurements of electroweak $Wjj$ production and constraints on anomalous gauge couplings with the ATLAS detector

Measurements of the electroweak production of a $W$ boson in association with two jets at high dijet invariant mass are performed using $\sqrt{s} = 7$ and $8$ TeV proton-proton collision data produced by the Large Hadron Collider, corresponding respectively to 4.7 and 20.2 fb$^{-1}$ of integrated luminosity collected by the ATLAS detector. The measurements are sensitive to the production of a $W$ boson via a triple-gauge-boson vertex and include both the fiducial and differential cross sections of the electroweak process.

初步电弱测量和对标准模型的约束的组合

A Combination of Preliminary Electroweak Measurements and Constraints on the Standard Model

本说明介绍了为2001年夏季会议准备的四个LEP协作和SLD协作的已发表和初步电弱结果的组合。从Z共振结果中导出了强子和轻子截面、轻子前后不对称性、τ极化不对称性、b-bbar和c-cbar部分宽度和前后不对称性以及q-qbar电荷不对称性。以上的Z共振，平均值导出的差费米子截面和前向后不对称性，W-对，Z-对和单W生产截面，电弱规范玻色子耦合，W的质量和宽度和W衰变分支比。第一次，总的和微分截面双光子生产相结合。相对于2000年夏天的实验结果的主要变化是更新的Z极重味结果从SLD和LEP和W质量从LEP。结果进行了比较，从其他实验中精确的电弱测量。使用一个新的评价的强子真空极化，标准模型的参数进行评估，首先使用组合LEP电弱测量，然后使用全套的电弱结果。

初步电弱测量和对标准模型的约束的组合

A Combination of Preliminary Electroweak Measurements and Constraints on the Standard Model

本文介绍了LEP四个合作项目ALEPH、DELPHI、L3和OPAL基于Z极以上质量中心能量的电子-正电子碰撞数据，从$130 \GeV$到$209 \GeV$（\LEPII），为2006年夏季会议准备的已发表和初步电弱结果的组合。导出了双费米子截面和前后不对称性、光子对、W对、Z对、单W和单Z截面、电弱规范玻色子耦合、W质量和宽度以及W衰变分支比等参数的近似解。本文研究了光子和Z玻色子交换的干涉，并结合色重联和玻色-爱因斯坦关联分析了W对的产生。相对于2005年提出的实验结果的主要变化是新的初步组合的最终{ \LEPII }结果的质量和宽度的W玻色子。包括最近发表的Z极进行的精密电弱测量，结果与其他实验，特别是CDF和DVDs在Tevatron的精密电弱测量进行了比较。对标准模型输入参数的约束来自于高$Q^2$相互作用的结果，并用于预测低$Q^2$实验的结果，如原子宇称破缺、M{<$}ller散射和中微子-核子散射。

精密电弱测量

Precision Electroweak Measurements

本文介绍了最近在e+e-和pbarp对撞机上进行的电弱精密测量。一些重点放在重口味部门的最新发展。的测量结果进行比较，预测从标准模型的电弱相互作用。所有结果均与标准模型一致。所有测量结果对顶夸克质量的间接约束与直接Mt测量结果非常一致。利用世界上的电弱数据，结合目前对顶夸克质量的测量，讨论了对希格斯质量的限制。

HERA上孤立的轻子事件：SUSY R-宇称违反？

Isolated Lepton Events at HERA: SUSY R-Parity Violation?

在HERA的H1实验中观察到的具有孤立的高$p_T$轻子、强子喷流和丢失能量的事件可能与超对称理论中的R宇称破坏有关。然而，严格的运动学约束必须得到满足，如果生产的超对称粒子在R-宇称违反的情况下是正确的路径来解释这些令人困惑的事件。一个参考点\RF指定这些约束条件的说明和影响的超对称解释的新类别的多轻子事件表示。

电弱模型及其对新物理学的制约

Electroweak Model and Constraints on New Physics

2004年版《粒子物理学评论》第10节。

来自电弱精密可观测量的对暗扇区的约束

Constraints on the dark sector from electroweak precision observables

该研究基于最新电弱精密数据及PDG与CDF两种W玻色子质量，重新拟合标准模型，并据此约束暗光子参数空间及其与费米子暗物质的耦合。

Electroweak constraints on new physics

We briefly review the limits on new interactions implied by electroweak precision data. Special attention is payed to the bounds on the Higgs boson mass. We also comment on the required cancellation among the new contributions to precisely measured electroweak observables in any Standard Model extension, if the new particles have to evade the indirect constraints on their couplings and masses but still remain at the LHC reach.

Combination of Measurements of Inclusive Deep Inelastic $e^{\pm}p$ Scattering Cross Sections and QCD Analysis of HERA Data

A combination is presented of all inclusive deep inelastic cross sections previously published by the H1 and ZEUS collaborations at HERA for neutral and charged current $e^{\pm}p$ scattering for zero beam polarisation. The data were taken at proton beam energies of 920, 820, 575 and 460 GeV and an electron beam energy of 27.5 GeV. The data correspond to an integrated luminosity of about 1 fb$^{-1}$ and span six orders of magnitude in negative four-momentum-transfer squared, $Q^2$, and Bjorken $x$. The correlations of the systematic uncertainties were evaluated and taken into account for the co…

Renormalization Group Constraints on New Top Interactions from Electroweak Precision Data

Anomalous interactions involving the top quark contribute to some of the most difficult observables to directly access experimentally. They can give however a sizeable correction to very precisely measured observables at the loop level. Using a model-independent effective Lagrangian approach, we present the leading indirect constraints on dimension-six effective operators involving the top quark from electroweak precision data. They represent the most stringent constraints on these interactions, some of which may be directly testable in future colliders.

Electroweak constraints on flavorful effective theories

We derive model-independent constraints arising from the Z and W boson observables on dimension six operators in the effective theory beyond the Standard Model. In particular, we discuss the generic flavor structure for these operators as well as several flavor patterns motivated by simple new physics scenarios.

来自电弱精确观测量的暗物质部分约束

Constraints on the dark sector from electroweak precision observables

本文基于PDG和CDF的W玻色子质量测量值重新进行了电弱精确观测量的标准模型拟合，引入暗光子并约束其参数空间，首次对暗光子与费米子暗物质部分的耦合施加了电弱精确观测值约束。

Update of the global electroweak fit and constraints on two-Higgs-doublet models

We present an update of the global fit of the Standard Model electroweak sector to latest experimental results. We include new kinematic top quark and $W$ boson mass measurements from the LHC, a $\sin^2θ^{\ell}_{\mathrm{eff}}$ result from the Tevatron, and a new evaluation of the hadronic contribution to $α(M_Z^2)$. We present tests of the internal consistency of the electroweak Standard Model and updated numerical predictions of key observables. The electroweak data combined with measurements of the Higgs boson coupling strengths and flavour physics observables are used to constrain parameter…

Z' Bosons from E(6): Collider and Electroweak Constraints

Many models beyond the Standard Electroweak Theory, top-down or bottom-up, contain extensions of the gauge symmetry group by extra U(1)' factors which can be understood or treated as subgroups of E(6). A brief overview of such models is followed by a sketch of a systematic classification. We then describe how the resulting extra massive neutral gauge bosons can be searched for and in case of positive evidence diagnosed using electroweak and collider data.

The electroweak fit and constraints on new physics

The global electroweak fit of the Standard Model (SM) with Gfitter can be used to constrain yet unknown SM parameters, such as the Higgs mass, but also physics beyond the SM (BSM) via the formalism of oblique parameters. This paper presents updated results of the Gfitter SM fit using the latest available electroweak precision measurements and the recent combination of direct Higgs searches at the Tevatron. In addition, newly obtained constraints on BSM models, such as models with extra dimensions, little Higgs and a fourth fermion generation, are presented. While a light Higgs mass is preferre…

顶夸克跷跷板、真空结构和电弱精确约束

Top Quark Seesaw, Vacuum Structure and Electroweak Precision Constraints

本文全面研究了电弱对称破缺的顶夸克跷跷板模型的真空结构，包括底夸克质量的产生。这样的模型自然地从额外维度中出现。我们进行了系统的间隙方程分析，并开发了一个改进的破碎相配方，包括确切的跷跷板混合。在大N_c费米子泡近似和改进的重整化群方法下研究了复合希格斯玻色子谱。理论上允许的参数空间是有限的，导致定义明确的预测。我们进一步分析了电弱精度约束。一般来说，一个重复合希格斯玻色子玻色子的质量约为1 TeV的预测，但完全符合精确的数据。

Electroweak precision constraints at present and future colliders

We revisit the global fit to electroweak precision observables in the Standard Model and present model-independent bounds on several general new physics scenarios. We present a projection of the fit based on the expected experimental improvements at future $e^+ e^-$ colliders, and compare the constraining power of some of the different experiments that have been proposed. All results have been obtained with the HEPfit code.

Constraints on Natural Supersymmetry from Electroweak Precision Tests

The observed Higgs boson mass and the naturalness argument leave us a narrow window for the soft mass spectrum in natural supersymmetry that can be studied through the electroweak precision tests (EWPTs). We divide the analysis into the Higgs sector constrained by the charged Higgs mass bound, the neutralino-chargino sector constrained by the chargino mass bound, and the third-generation squark sector tightly constrained by the observed Higgs mass. Total contributions to EWPTs in the MSSM and NMSSM are both presented. It turns out that natural MSSM is excluded at 68\% CL but consistent at 95\%…

Improved Constraints on Z' Bosons from Electroweak Precision Data

We analyze various models with an extra U(1) gauge symmetry in addition to the Standard Model (SM) gauge group at low energies, and impose limits on the mass of the neutral Z' boson, M_Z', predicted in all such models, and on the Z-Z' mixing angle, theta_ZZ'. The precision electroweak data strongly constrain theta_ZZ' to very small values and for most models we find lower limits on M_Z' of order 1 TeV. In one case we obtain a somewhat better fit than in the SM (although this is only marginally statistically significant) and here we find a weak upper limit at the 90% C.L.

Electroweak phase transition confronted with dark matter detection constraints

We study the type-II first-order electroweak phase transition and dark matter (DM) phenomenology in both real and complex singlet extensions of SM. In the real singlet extension with a $\mathbb{Z}_2$ symmetry, we show that the parameter regions favored by the phase transition suffer from strong constraints from DM direct detection so that only a negligible fraction ($f_{X}\sim 10^{-4}-10^{-5}$) of DM composed of the real singlet scalar can survive the LUX and XENON1T constraints. In the complex singlet $S$ case, we impose a $CP$ symmetry $S\to S^{*}$ to the scalar potential. The real component…

来自新电弱数据的轻夸克与反夸克约束

Light quark and antiquark constraints from new electroweak data

本文通过纳入W玻色子和轻子对产生的新电弱数据，对质子轻反夸克分布函数进行新分析，发现d/u与$\ar{d}/\ar{u}$比值间的相关性并修正了此前d/u在大x区域的结果。