کتاب الکترونیکی سی. پی.اچ
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نسبت پژوهش به جامعه، مانند اندیشه است به انسان- جوادی، کتاب گنجهای نیمه پنهان
اظهار نظرها درمورد نظریه سی. پی. اچ
تماس با ما
سمینارها
بنیاد حمایت از نخبگان ایران
پاد (ضد) ذرات
اگر همواره مانند گذشته بينديشيد، هميشه همان چيزهايي را به‌دست مي‌آوريد كه تا بحال كسب كرده‌ايد، فاينمن
معاونت پژوهشی و فناوری دانشگاه تهران
خانه
نظریه سی. پی.اچ
دوستان سلام
با توجه به استقبال شایان توجه از سایت سی. پی. اچ. و تقاضای مکرر دوستان مبنی بر انتشار همزمان مقالات به دو زبان فارسی - انگلیسی ابرای آشنایی بیشتر کاربران گرامی، این سری مقالات منتشر شد. لذا از دوستان علاقهمند که توان ترجمه از انگلیسی به فارسی را دارند، تقاضا می شود نسبت به ترجمه این مقالات اقدام کنند تا با نام خودشان در سایت قرار گیرد. امید است با همکاری دوستان عزیز بتوانیم در افزایش منابع فارسی فیزیک گامی برداریم. برای ارسال مقالات ترجمه شده و تبادل نظر با آدرس زیر تماس بگیرید.
با تشکر - حسین جوادی
javadi_hossein@hotmail.com
In particle physics, every particle has a corresponding antiparticle. A particle and its antiparticle have identical mass and spin.
A particle and its antiparticle have opposite values for all other non-zero quantum number labels. These labels are electric charge, color charge, flavor, electron number, muon number, tau number, and baryon number. Every fermion (lepton and quarks) carries some charge-like quantum number labels, and each has a distinct antiparticle partner with opposite values for those labels. For example, the antiparticle of an electron is a positron -- it has exactly the same mass as an electron but positive electric charge. (The positron is the only antiparticle with its own name. In all other cases, the name of the antiparticle is anti- in front of the name of the particle, such as proton and anti-proton.) Charged bosons always have an antiparticle partner of opposite charge and equal mass. For charge zero mesons with different types of quark and antiquark, there is an antiparticle partner of that reverses the role of quark and antiquark. The Ko meson and its antiparticle have the following composition. Symbol Name Quarks Anti-quarks K-zero d quark s anti-quark K-zero-bar s quark d anti-quark For charge zero mesons with the same type of quark and antiquark, and for the charge zero force carriers (photon and Z), the particle and the antiparticle are identical. The antiparticle of a photon is a photon, likewise the antiparticle of a phi meson (s quark and anti-s quark) is a phi meson. Gluons are force carriers with zero electric charge, but each type of gluon has a color charge. Thus each gluon has a corresponding antiparticle with a related color charge.
A particle and its antiparticle have opposite values for all other non-zero quantum number labels. These labels are electric charge, color charge, flavor, electron number, muon number, tau number, and baryon number.
Every fermion (lepton and quarks) carries some charge-like quantum number labels, and each has a distinct antiparticle partner with opposite values for those labels. For example, the antiparticle of an electron is a positron -- it has exactly the same mass as an electron but positive electric charge. (The positron is the only antiparticle with its own name. In all other cases, the name of the antiparticle is anti- in front of the name of the particle, such as proton and anti-proton.)
Charged bosons always have an antiparticle partner of opposite charge and equal mass. For charge zero mesons with different types of quark and antiquark, there is an antiparticle partner of that reverses the role of quark and antiquark. The Ko meson and its antiparticle have the following composition.
For charge zero mesons with the same type of quark and antiquark, and for the charge zero force carriers (photon and Z), the particle and the antiparticle are identical. The antiparticle of a photon is a photon, likewise the antiparticle of a phi meson (s quark and anti-s quark) is a phi meson.
Gluons are force carriers with zero electric charge, but each type of gluon has a color charge. Thus each gluon has a corresponding antiparticle with a related color charge.
We call commonly observed particles such as protons, neutrons, and electrons "matter" particles, and their antiparticles are then "antimatter." The term matter is then extended, by convention, to include: All quarks, (charges +2/3 and -1/3). All negatively charged leptons. Left handed neutrinos. Antimatter is, then, any particle built from: Antiquarks (charges of -2/3 or +1/3). Positively charged leptons. Right-handed neutrinos. A particle made from quarks, such as a baryon, is called matter. Similarly, a particle made from antiquarks, such as the antibaryon, is called antimatter. For bosons, there is no distinction between matter and antimatter. These classifications simply do not apply. For example, a positively charged pion contains an up type quark and a down type antiquark. The negatively charged pion contains a down type quark and up type antiquark. Each of these particles is the antiparticle of the other, but neither can be called either matter or antimatter. Similarly, force carrier particles cannot be classified as either matter or antimatter. In The Standard Model, properties of matter and antimatter are almost identical. One of the big mysteries of cosmology (the theory of the evolution of the universe) is to explain why the universe contains matter in preference to antimatter. A universe where matter and antimatter occurred equally would not contain galaxies, but only black-body radiation - like the microwave background seen in all directions. Want to learn more about antimatter? Take a look at a Scientific American "Ask the Experts" column written by R. Michael Barnett of the Lawrence Berkeley National Laboratory and Helen Quinn (left) of the Stanford Linear Accelerator Center.
We call commonly observed particles such as protons, neutrons, and electrons "matter" particles, and their antiparticles are then "antimatter."
The term matter is then extended, by convention, to include:
Antimatter is, then, any particle built from:
A particle made from quarks, such as a baryon, is called matter. Similarly, a particle made from antiquarks, such as the antibaryon, is called antimatter.
For bosons, there is no distinction between matter and antimatter. These classifications simply do not apply. For example, a positively charged pion contains an up type quark and a down type antiquark. The negatively charged pion contains a down type quark and up type antiquark. Each of these particles is the antiparticle of the other, but neither can be called either matter or antimatter. Similarly, force carrier particles cannot be classified as either matter or antimatter.
In The Standard Model, properties of matter and antimatter are almost identical. One of the big mysteries of cosmology (the theory of the evolution of the universe) is to explain why the universe contains matter in preference to antimatter. A universe where matter and antimatter occurred equally would not contain galaxies, but only black-body radiation - like the microwave background seen in all directions.
Want to learn more about antimatter? Take a look at a Scientific American "Ask the Experts" column written by R. Michael Barnett of the Lawrence Berkeley National Laboratory and Helen Quinn (left) of the Stanford Linear Accelerator Center.
Whenever sufficient energy is available to provide the mass-energy, a particle and its matching antiparticle can be produced together. All the conservation laws apply in these processes. When a particle collides with a matching antiparticle, they may annihilate--which means they both disappear. Their energy appears in the form of some fundamental boson--a gluon, a photon or a Z particle. The bosons then decay to produce other particles and antiparticles. During any process, the number of particles plus antiparticles of a related type are conserved -- their total is the same before and after the process. In weak interaction processes, a quark and antiquark of different flavors can annihilate into, or be produced by decay of a W boson. The total charge of the pair must be +1 or -1. W bosons can also decay to produce, or be produced from annihilation of, a charge -1 lepton and a matching anti-neutrino, or an anti-lepton (charge +1) and its matching neutrino.
Whenever sufficient energy is available to provide the mass-energy, a particle and its matching antiparticle can be produced together. All the conservation laws apply in these processes.
When a particle collides with a matching antiparticle, they may annihilate--which means they both disappear. Their energy appears in the form of some fundamental boson--a gluon, a photon or a Z particle. The bosons then decay to produce other particles and antiparticles. During any process, the number of particles plus antiparticles of a related type are conserved -- their total is the same before and after the process.
In weak interaction processes, a quark and antiquark of different flavors can annihilate into, or be produced by decay of a W boson. The total charge of the pair must be +1 or -1. W bosons can also decay to produce, or be produced from annihilation of, a charge -1 lepton and a matching anti-neutrino, or an anti-lepton (charge +1) and its matching neutrino.
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