粒子探测器的进展

本文简要地评述粒子探测器的发展近况。文中讨论了以下问题:大型高能粒子探测器、高能实验电子学及探测器物理。     

Prospects for detecting supersymmetric dark matter at Post-LEP benchmark points

A new set of supersymmetric benchmark scenarios has recently been proposed in the context of the constrained MSSM (CMSSM) with universal soft supersymmetry-breaking masses, taking into account the constraints from LEP, and . These points have previously been used to discuss the physics reaches of different accelerators. In this paper, we discuss the prospects for discovering supersymmetric dark matter in these scenarios. We consider direct detection through spin-independent and spin-dependent nuclear scattering, as well as indirect detection through relic annihilations to neutrinos, photons, and positrons. We find that several of the benchmark scenarios offer good prospects for direct detection via spin-independent nuclear scattering and indirect detection via muons produced by neutrinos from relic annihilations inside the Sun, and some models offer good prospects for detecting photons from relic annihilations in the galactic centre. Received: 17 October 2001 / Revised version: 14 January 2002 / Published online: 12 April 2002     

Looking for physics beyond the Standard Model

Motivations for new physics beyond the Standard Model are presented. The most successful and best motivated option, supersymmetry, is described in some detail, and the associated searches performed at LEP are reviewed. These include searches for additional Higgs bosons and for supersymmetric partners of the standard particles. These searches constrain the mass of the lightest supersymmetric particle which could be responsible for the dark matter of the universe. To cite this article: P. Binétruy, J.-F. Grivaz, C. R. Physique 3 (2002) 1235–1243.     

Dark light-Higgs bosons

We study a limit of the nearly Peccei-Quinn-symmetric next-to-minimal supersymmetric standard model possessing novel Higgs and dark matter (DM) properties. In this scenario, there naturally coexist three light singletlike particles: a scalar, a pseudoscalar, and a singlinolike DM candidate, all with masses of order 0.1-10 GeV. The decay of a standard model-like Higgs boson to pairs of the light scalars or pseudoscalars is generically suppressed, avoiding constraints from collider searches for these channels. For a certain parameter window annihilation into the light pseudoscalar and exchange of the light scalar with nucleons allow the singlino to achieve the correct relic density and a large direct-detection cross section consistent with the DM direct-detection experiments, CoGeNT and DAMA/LIBRA, preferred region simultaneously. This parameter space is consistent with experimental constraints from LEP, the Tevatron, Υ, and flavor physics.     

Tevatron: Recent results and prospects at the upgrade

In this article, we review some of the recent results from CDF and DØ experiments at the Tevatron and their prospects at the upgrade. Among the topics discussed are top quark physics, electroweak physics, qcd physics and new physics beyond standard model.     

电子-质子对撞机上的Primakoff物理

Primakoff效应具有独特的动力学筛选条件,是研究原子核和粒子物理的强大的实验工具。未来电子-离子对撞机(EIC)机器具有质心能量高、亮度高、动力学范围广、本底低、探测器探测效率高以及碰撞离子种类丰富等优点。这将为我们开启一扇通往Primakoff物理研究的新时代的大门。在EIC机器上开展Primakoff物理实验可以严格检验量子色动力学的基本对称性,研究强子的电弱相互作用性质,并探索超出标准模型的新物理。Primakoff效应实验是EIC物理研究的又一亮点。     

Vector WIMP miracle

Weakly interacting massive particle (WIMP) is well known to be a good candidate for dark matter, and it is also predicted by many new physics models beyond the standard model at the TeV scale. We found that, if the WIMP is a vector particle (spin-one particle) which is associated with some gauge symmetry broken at the TeV scale, the Higgs mass is often predicted to be 120–125 GeV, which is very consistent with the result of Higgs searches recently reported by ATLAS and CMS Collaborations at the Large Hadron Collider experiment. In this Letter, we consider the vector WIMP using a non-linear sigma model in order to confirm this result as general as possible in a bottom-up approach. Near-future prospects to detect the vector WIMP at both direct and indirect detection experiments of dark matter are also discussed.     

Model Independent QED Corrections to the Process ep → eX

We give an exhaustive presentation of the semi-analytical approach to the model independent leptonic QED corrections to deep inelastic neutral current lepton-nucleon scattering. These corrections include photonic bremsstrahlung from and vertex corrections to the lepton current of the order φ(α) with soft photon exponentiation. A common treatment of these radiative corrections in several variables — leptonic, hadronic, mixed, Jaquet-Blondel variables — has been developed and double differential cross sections are calculated. In all sets of variables we use some structure functions, which depend on the hadronic variables and which do not have to be defined in the quark parton model. The remaining numerical integrations are twofold (for leptonic variables) or onefold (for all other variables). For the case of hadronic variables, all phase space integrals have been performed analytically. Numerical results are presented for a large kinematical range, covering fixed target as well as collider experiments at HERA or LEP⊗LHC, with a special emphasis on HERA physics.     

MiniBooNE overview and status

Recent discoveries in the neutrino sector have opened a new frontier in highenergy physics and cosmology. Evidence from neutrino oscillation experiments from around the world indicate that neutrinos oscillate between their different flavours and therefore may have mass. In addition, results from solar and atmospheric neutrino experiments as well as the accelerator neutrino experiment, LSND, cannot all be explained with the three standard model neutrinos. Is this new physics or is there some other explanation? The MiniBooNE experiment presently taking data at Fermilab is designed to address the LSND signal and answer this question. Progress on the MiniBooNE experiment will be presented and prospects for the future will be discussed.     

物质结构在夸克-轻子层次上的动力学规律和研究发展趋势

文章综述了粒子物理中标准模型理论的历史发展、面临挑战以及未来的发展趋势.目前阶段物质结构最小组成单元是夸克和轻子,量子色动力学是描述夸克-胶子之间强相互作用的基本理论,它具有渐近自由和夸克禁闭的特点.量子色动力学和电弱统一理论一起构成粒子物理中标准模型理论.标准模型理论成功同时也面临两大挑战:对称性破缺的本质和夸克禁闭难题,这意味着标准模型理论需要发展和突破.人们期望粒子物理学、天文学和宇宙学交叉发展联手解决物质结构和早期宇宙研究中面临的难题,最终揭示超出标准模型的新物理规律.     

The second greatest story ever told

During the past two decades, cosmologists turned to particle physics in order to explore the physics of the very early Universe. The main link between the physics of the smallest and largest structures in the Universe is the idea of spontaneous symmetry breaking, familiar from condensed matter physics. Implementing this mechanism into cosmology leads to the interesting possibility that phase transitions related to the breaking of symmetries in high energy particle physics took place during the early history of the Universe. These cosmological phase transitions may help us understand many of the challenges faced by the standard hot Big Bang model of cosmology, while offering a unique window into the very early Universe and the physics of high energy particle interactions.     

Direct detection of WIMP dark matter

The question of the nature of dark matter in the universe is perhaps the greatest problem facing cosmology and particle physics at present. New observations of the cosmic microwave background radiation and distant supernovae show that more that 90% of the mass in the universe is in the form of some unknown matter. Many lines of evidence from cosmology and particle physics suggest that the best candidate for this dark matter is a weakly interacting massive particle, or WIMP. Such particles are predicted by supersymmetry, a theory extending the Standard Model of particle physics, and many experiments around the world are now trying to directly detect these WIMPs. This article reviews the reasons for believing WIMPs to be the dark matter, and considers the challenges involved in detecting their rare low-energy interactions with normal matter. Current experimental searches are reviewed with regard to the claimed detection of WIMPs by the DAMA group. These experiments are just beginning to reach the sensitivity needed to detect, or rule out, supersymmetric WIMPs, and higher sensitivity future experiments are also discussed.     

Supersymmetric technicolor

We propose a supersymmetric model of particle physics in which supersymmetry is broken dynamically by strong gauge forces. The model, as it stands, requires that one parameter be fine tuned; a grand unified version would not require any fine tuning. The model has no strong CP problem, and agrees with all known particle physics experiments. A variety of new particles, many of which weigh less than 100 GeV, are predicted.     

Neutral Higgs bosons in the standard model and in the minimal supersymmetric model: Searches at LEP

During the twelve years of operation of thee ⁺ e ⁻ collider LEP, the associated collaborations, ALEPH, DELPHI, L3 and OPAL, have extensively searched for Higgs bosons over a broad range of masses. We present the final results from LEP for the standard model Higgs boson which are obtained from a statistical combination of the data from the four experiments. We also present preliminary combined results for neutral Higgs bosons in the minimal supersymmetric model (MSSM) where the Higgs sector is assumed to be CP invariant. Finally, we discuss an alternative MSSM scenario including CP violation in the Higgs sector.     

Supersymmetry and LHC

Motivations for introducing supersymmetry in high-energy physics are discussed along with the possibility of discovering supersymmetry at the Large Hadron Collider (LHC). Various regions of the space of parameters of the minimal supersymmetric standard model are analyzed, and phenomenological manifestations of supersymmetry inherent in these regions are discussed. The discovery potential of LHC at the planned luminosity is indicated for various channels.     

LEP Higgs boson searches beyond the standard model and minimum supersymmetric standard model

Ever since the center-of-mass energy was increased in 1995 above the Zℴ resonance, the four LEP experiments (ALEPH, DELPHI, OPAL and L3) have renewed their effort to search for the Higgs boson. Data taking ended in the year 2000 with about 130 pb⁻¹ of data collected per experiment above 206 GeV ine ⁺ e ⁻¹ collisions but the data analysis is still very active. Most recently, the wealth of theoretical models and predictions has stimulated new analyses and model interpretations which go beyond the standard model and minimal supersymmetric standard model. These include the searches for charged Higgs bosons, models with two Higgs field doublets, searches for ‘fermiophobic’ Higgs decay, invisible Higgs boson decays, decay-mode independent searches, and limits on Yukawa and anomalous Higgs couplings. I review the searches done by the four LEP experiments and present the LEP combined results when they exist.