反粒子·反物质·反物质武器

 反粒子的发现是现代物理学的一项重大成就。在微观物理研究领域,每个粒子都存在着它的反粒子。据此,人们推测在宏观或宇观世界,应存在着由反质子、反中子和正电子构成的反物质。下面简要介绍反粒子、反物质与反物质武器的有关问题。一、反粒子1928年,英国理论物理学家狄拉克（PaulAdri-enMauriceDirac,1902～1984）提出了一个关于电子运动的相对论性量子力学理论,建立了著名的狄拉克方程。     

√SNN=130GeV时Au+Au碰撞中的反重子与重子比率

按照夸克随机组合的简单组合模型, 本文通过分析得出重子反重子比率与夸克反夸克平均产生几率的关系. 进一步计算了相对论重离子碰撞过程中各种反粒子与粒子的比率, 不需要任何额外假定, 预言的比率与RHIC加速器√S_NN=130GeV时Au+Au碰撞STAR实验的结果基本一致. 表明夸克组合模型能够解释相对论重离子碰撞过程的反粒子与粒子比率.     

(S_(NN))~(1/2)=130GeV时Au Au碰撞中的反重子与重子比率

按照夸克随机组合的简单组合模型,本文通过分析得出重子反重子比率与夸克反夸克平均产生几率的关系．进一步计算了相对论重离子碰撞过程中各种反粒子与粒子的比率,不需要任何额外假定, 预言的比率与RHIC加速器时Au Au碰撞STAR实验的结果基本一致．表明夸克组合模型能够解释相对论重离子碰撞过程的反粒子与粒子比率．     

重子物质与反重子暗物质统一的起源

美国和加拿大的物理学家提出一种新粒子可以解决现代物理的两个重要疑难问题:暗物质是什么以及为什么宇宙中的物质远比反物质多?预计这种有待发现的粒子主要衰变成正物质,而其反粒子主要衰变成隐藏的反物质.研究人员声称,这种粒子在早期宇宙中的存在可以说明为何宇宙中物质比反物质多,以及暗物质实际上是隐藏的反物质.     

反氢原子

报导并评述了反氢原子的发现，反氢原子是反地撮简单的原子的束缚态，它是一个全新的原子，将对ＣＰＴ定量提供一个根本性的检验。     

关于中微子的意外发现

费米实验室的MINOS实验组宣布了一个可能表明中微子与其反粒子之间的重要差别的结果.这一令人惊奇的发现,如果被进一步的实验所证实的话,会有助于物理学家探索物质与反物质之间的某些基本差别.     

新科学和新技术——反中子的发现

1956年年底,在美国贝克莱城的加尼福尼亚大学,发现了一个新的反粒子——反中子,这是利用在贝伐加速器(Bevatron)中将质子加速到62亿电子伏特(6.2Bev.)后而得到的。要知道反中子具有那些特性,有必要来叙述一番一些反粒子的发现史。     

反粒子

在1955和1956年间,曾经发现了两种新的基本粒子,这就是理论物理学预言已久的反质子和反中子。自然,这些发现引起人们对反粒子理论的巨大注意。反质子、反粒子这些名称以及反物质这类术语本身就吸引了普遍的注意。这些名称能引起强烈的兴趣,因为它们说明,问题涉及某种在原则上是全新的东西,也涉及一系列由一个共同的思想所统一起来的现象。同时,这些名词的第一个字——“反”字——有时本身就会引起人们的警惕,假如不说是引起怀疑的话。所谓“反粒子”究竟是什么东西呢?它们和     

反粒子·反物质·反物质武器

反粒子的发现是现代物理学的一项重大成就。在微观物理研究领域,每个粒子都存在着它的反粒子。据此,人们推测在宏观或宇观世界,应存在着由反质子、反中子和正电子构成的反物质。下面简要介绍反粒子、反物质与反物质武器的有关问题。一、反粒子1928年,英国理论物理学家狄拉克(Paul Adri-en Maurice Dirac,1902~1984)提出了一个关于电子运动的相对论性量子力学理论,建立了著名的狄拉克方程。该方程给出了氢原子能级的精细结构,还可以很好地说明高速运动电子的许多重要性质,如电子的自旋量子数为1/2、电子自旋磁矩与自旋角动量和轨道角动量的…     

高能极化粒子、反粒子总截面的对称性

本文把关于非极化粒子、反粒子对固定靶散射的И.Я.Померанчук定理推广到极化粒子、反粒子的情况,而得到在高能下一系列极化粒子、反粒子总截面的对称关系。     

Gamma ray astronomy and search for antimatter in the universe

Gamma ray astronomy provides a powerful tool for searching antimatter in the universe; it probably provides the only means to determine, if the universe has baryon symmetry. Presently existing gamma-ray observations can be interpreted without postulating the existence of antimatter. However, the measurements are not precise enough to definitely exclude the possibility of its existence. The search for antimatter belongs to one of the main scientific objectives of the Gamma Ray Observatory GRO of NASA, which will be launched in 1990 by the Space Shuttle.     

CP violation and the matter–antimatter asymmetry of the Universe

In our everyday environment one observes only matter. Thatʼs quite a fortunate situation! Any sizeable presence of antimatter on Earth, from the enormous energy it would release through annihilation with matter, would prevent us talking about it! For the physicist this fact, at first sight obvious, is nevertheless a kind of surprise: antimatter, which is observed in cosmic rays, in radioactive decays of nuclei, which has been copiously produced and extensively studied in accelerators and which is nowadays currently used in hospitals, turns out to have pretty much the same properties as matter. Moreover, the fact that matter dominates appears to be a general property of our Universe: no evidence of large quantities of antimatter has been observed at any distance from us. Why would matter have taken the advantage on antimatter? In this short review we explain how, through a limited number of basic elements, one can find answers to this question. Matter and antimatter have, in fact, not exactly the same properties: from laboratory experiments CP conservation is known not to be a fundamental law of nature.     

Elementary Process Theory: a formal axiomatic system with a potential application as a foundational framework for physics supporting gravitational repulsion of matter and antimatter

Theories of modern physics predict that antimatter having rest mass will be attracted by the earth's gravitational field, but the actual coupling of antimatter with gravitation has not been established experimentally. The purpose of the present research was to identify laws of physics that would govern the universe if antimatter having rest mass would be repúlsed by the earth's gravitational field. As a result, a formalized axiomatic system was developed together with interpretation rules for the terms of the language: the intention is that every theorem of the system yields a true statement about physical reality. Seven non‐logical axioms of this axiomatic system form the Elementary Process Theory (EPT): this is then a scheme of elementary principles describing the dynamics of individual processes taking place at supersmall scale. It is demonstrated how gravitational repulsion functions in the universe of the EPT, and some observed particles and processes have been formalized in the framework of the EPT. Incompatibility of Quantum Mechanics (QM) and General Relativity (GR) with the EPT is proven mathematically; to demonstrate applicability to real world problems to which neither QM nor GR applies, the EPT has been applied to a theory of the Planck era of the universe. The main conclusions are that a completely formalized framework for physics has been developed supporting the existence of gravitational repulsion and that the present results give rise to a potentially progressive research program.     

Antimatter gravity studies with interferometry

There has never been a direct measurement of the gravitational force on antimatter. This paper describes a possible measurement of this force by measuring the phase shift of neutral antimatter in a transmission-grating interferometer caused by the Earth’s gravitational field. This experiment avoids the severe problem of shielding stray electromagnetic fields necessary for making a gravity measurement with charged particles, and also avoids the need to trap neutral particles. The neutral antimatter for this experiment could be either antihydrogen, positronium, or antineutrons. This revised version was published online in August 2006 with corrections to the Cover Date.     

Anti-helium flux as a signature for antimatter globular clusters in our Galaxy

The Alpha Magnetic Spectrometer experiment is shown to be sensitive to test the hypothesis on the existence of antimatter globular cluster in our Galaxy. The hypothesis follows from the analysis of possible tests for the mechanisms of baryosynthesis and uses antimatter domains in the matter-dominated Universe as the probe for the physics underlying the origin of matter. The interval of masses for the antimatter in our Galaxy is fixed from below by the condition of antimatter domain survival in the matter-dominated Universe and from above by the observed gamma-ray flux. For this interval, the expected fluxes of anti-helium-3 and anti-helium-4 are calculated with account for their interaction with the matter in the Galaxy.     

The AEgIS antihydrogen gravity experiment

The experimental program of the AEgIS experiment at CERN’s AD complex aims to perform the first measurement of the gravitational interaction of antimatter, initially to a precision of about 1%, to ascertain the veracity of Einstein’s Weak Equivalence Principle for antimatter. As gravity is very much weaker than electromagnetic forces, such an experiment can only be done using neutral antimatter. The antihydrogen atoms also need to be very cold for the effects of gravity to be visible above the noise of thermal motion. This makes the experiment very challenging and has necessitated the introduction of several new techniques into the experimental field of antihydrogen studies, such as pulsed formation of antihydrogen via 3-body recombination with excited state positronium and the subsequent acceleration of the formed antihydrogen using electric gradients (Stark acceleration). The gravity measurement itself will be performed using a classical Moire deflectometer. Here we report on the present state of the experiment and the prospects for the near future.     

On a Purely Geometric Approach to the Dirac Matter Field and Its Quantum Properties

We consider the most general axial torsion completion of gravity with electrodynamics for $\frac{1}{2}$ -spin spinors in an 8-dimensional representation of the Dirac matter field: this theory will allow to define antimatter as matter with all quantum numbers reversed, where also the sign of the mass beside that of the charge is inverted: we shall see that matter and antimatter solutions of the Dirac field equations coincide with the known ones with respect to all observables, that despite the inversion of the sign of the mass term only positive-mass states are present and only positive-energy densities are given; the present and the common approach will be compared, and some experimental implications will be discussed.     

AEGIS at CERN: Measuring Antihydrogen Fall

The main goal of the AEGIS experiment at the CERN Antiproton Decelerator is testing fundamental laws such as the weak equivalence principle (WEP) and the CPT symmetry. In the first phase of AEGIS, a beam of antihydrogen will be formed whose fall in the gravitational field is measured in a Moirè deflectometer; this will constitute the first test of the WEP with antimatter.     

ALPHA: antihydrogen and fundamental physics

Detailed comparisons of antihydrogen with hydrogen promise to be a fruitful test bed of fundamental symmetries such as the CPT theorem for quantum field theory or studies of gravitational influence on antimatter. With a string of recent successes, starting with the first trapped antihydrogen and recently resulting in the first measurement of a quantum transition in anti-hydrogen, the ALPHA collaboration is well on its way to perform such precision comparisons. We will discuss the key innovative steps that have made these results possible and in particular focus on the detailed work on positron and antiproton preparation to achieve antihydrogen cold enough to trap as well as the unique features of the ALPHA apparatus that has allowed the first quantum transitions in anti-hydrogen to be measured with only a single trapped antihydrogen atom per experiment. We will also look at how ALPHA plans to step from here towards more precise comparisons of matter and antimatter.     

CP violation in the neutrino sector: The new frontier

The discovery of neutrino masses has revealed a new flavour sector in the Standard Model. Just like the quark flavour sector, it contains a seed of CP violation, resulting in an asymmetric behaviour of matter and antimatter. It is argued that this new source of leptonic CP violation may be discovered in more precise neutrino oscillation experiments involving neutrino beams with energies in the GeV range that will be sent to distances of a few thousand kilometres.