A hadron is a class of subatomic particles that are made of quarks and thus interact through the medium of the strong force. The hadrons include baryons (e.g., neutrons, protons, etc.), mesons, and their various resonances. Every detected subatomic particle is in the class of hadrons except for the gauge bosons of the basic interactions and the leptons. Except for neutrons and protons that are attached to the atomic nuclei, every hadron has a short lifespan and is generated in the high-energy bombardment of subatomic particles. The other fundamental forces also affect hadron characteristics. Every hadron is under the influence of gravitation, charged hadrons follow electromagnetic laws, and some types of hadrons disintegrate through the weak force, while other hadrons decay through the electromagnetic and strong force. Rare hadrons are hadrons that are composed of more than three valence quarks that have been detected recently. A tetraquark state (rare meson) was detected in 2007 and established as resonance by the LHCb in 2014.
As per the quark framework, the characteristics of hadrons are predominantly found by analysing their valence quarks. A proton is made up of one down quark and two up quarks. Mixing these together results in the proton charge +1. Even though quarks also possess colour charge, hadrons must possess zero net colour charge due to a process known as colour confinement. This means that hadrons must be “white” or “colourless”. The basic ways for this to happen are with a quark of one colour and an antiquark of the respective anticolour or three quarks of varied colours.
Baryons are hadrons comprising an odd number of quarks (three quarks). The most well-known baryons, such as neutrons and protons, have three quarks. Mesons are hadrons that are composed of an even count of valence quarks (minimum two quarks). The most well-known mesons are made of a quark-antiquark pair. Many hypothetical kinds of exotic meson may occur which are not under the classification of quark models. Such particles include hybrid mesons (mesons held together by excited gluons) and glueballs. Examples of commonly generated mesons in particle physics are kaons and pions. Pions play an important role in bonding atomic nuclei together through the strong force.
The Large Hadron Collider (LHC) is the most powerful and largest particle accelerator in the world. LHC was officially launched on September 10th, 2008. It is the most important part of the entire CERN complex. The Large Hadron Collider is made of 27 km of superconducting magnets ring with many accelerating parts to enhance the particles’ energy along the way. In the accelerator, two highly energetic particle beams move at speed near the speed of light, and they are forced to collide.
Important Hadron Questions Questions with Answers
1) What is meant by hadrons?
A hadron is a composite subatomic particle composed of two or more quarks bound together by a strong interaction. This is similar to the way that molecules are glued together by the electric force of attraction. Most of the mass of normal matter arises from two hadrons which are protons and neutrons. Most of the mass of the neutrons and protons comes from their constituent quarks (held together by the strong force).
2) Every detected subatomic particle is in the class of hadrons except for the _______ of the basic interactions and the leptons.
Answer: gauge bosons
Explanation: Every detected subatomic particle is in the class of hadrons except for the gauge bosons of the basic interactions and the leptons.
3) What are the two types of hadrons?
Hadrons are categorised into two extensive branches: the baryons and mesons. Baryons are composed of an odd number of quarks. They usually consist of three quarks. Protons and neutrons are examples of baryons. Mesons are composed of an even number of quarks. They usually have two quarks; one normal quark and one antiquark. Pions are one of the common examples of mesons.
4) What are rare hadrons?
Rare hadrons are hadrons that are composed of more than three valence quarks that have been detected recently.
5) How are the characteristics of hadrons determined?
According to the quark framework, the characteristics of hadrons are predominantly found by analysing their valence quarks. A proton is made up of one down quark and two up quarks. Mixing these together results in the proton charge +1. Even though quarks also possess colour charge, hadrons must possess zero net colour charge due to a process known as colour confinement. This means that hadrons must be “white” or “colourless”. The basic ways for this to happen are with a quark of one colour and an antiquark of the respective anticolour or three quarks of varied colours.
6) What is meant by baryons?
Baryons are hadrons comprising an odd number of quarks (three quarks). The most well-known baryons, such as neutrons and protons, have three quarks. On the other hand, pentaquarks which have five quarks – three different coloured quarks and one additional quark-antiquark pair also exist. As baryons possess an odd count of quarks, they are also considered fermions (they possess half-integer spin). Quarks have baryon number B = â…“, and baryons possess baryon number B = 1. Since extra antiquarks’ and quarks’ baryon numbers cancel, pentaquarks also possess B = 1.
7) What is meant by mesons?
Mesons are hadrons that are composed of an even count of valence quarks (minimum two quarks). The most well-known mesons are made of a quark-antiquark pair. However, possible tetraquarks (four quarks) and hexaquarks (six quarks, composed of either three quark-antiquark pairs or a dibaryon) could have been detected and are currently examined to confirm their properties.
8) The examples of commonly generated mesons in particle physics are _______________.
Answer: kaons and pions
Explanation: The examples of commonly generated mesons in particle physics are kaons and pions.
9) A tetraquark state (rare meson) was detected in 2007 and established as resonance by the _______ in 2014.
Answer: LHCb
Explanation: A tetraquark state (rare meson) was detected in 2007 and established as resonance by the LHCb in 2014.
10) Give a brief description about the Large Hadron Collider (LHC).
The Large Hadron Collider (LHC) is the most powerful and largest particle accelerator in the world. LHC was officially launched on September 10th, 2008. It is the most important part of the entire CERN complex. The Large Hadron Collider is made of 27 km of superconducting magnets ring with many accelerating parts to enhance the particles’ energy along the way. In the accelerator, two highly energetic particle beams move at speed near the speed of light, and they are forced to collide. The particle beams move in opposite orientations in separate pipes (two pipes are at extreme vacuum. The beams are directed around the accelerator path by an intense magnetic field regulated by superconducting electromagnets. These electromagnets are constructed from special electric cable coils that work in a superconducting condition, smoothly conducting electric energy without loss of energy or resistance. This needs cooling of the magnets to a super cold temperature of about ‑271.3°C (colder than outer space). Due to this background, significant parts of the accelerator are attached to a liquid helium distribution system, which chills the magnets and other supply services.
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Practice Questions
1) What is meant by particle physics?
2) What are the differences between baryons and mesons?
3) What is meant by strong nuclear force?
4) What is meant by a quark?
5) What is the relationship between hadrons and quarks?
6) What are the different types of quarks that exist in hadrons?
7) What are the factors that affect the properties of hadrons?
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