Antistrange Quark
Composition :
Statistics : Generation :
Family :
Interaction forces :
Symbol :
Antiparticle :
Mass :
Decays into :
Electric charge :
Color charge
Spin :
Weak isospin :
Elementary antiparticle
Fermionic
Second
Quark
strong, weak,
electromagnetic force
gravity
Strange quark ( s )
2.2 MeV/c²
strange quark (~95%)
down quark (~5%)
+¹∕₃ e
Yes
¹/₂
LH = -¹/₂; RH = 0
+ 0,5
- 0,4
General
The antistrange quark, often denoted as s̅ (pronounced "s-bar"), is a fundamental subatomic particle and a type of antiquark. Antiquarks are the counterparts to quarks, and they possess the opposite electric charge, color charge, and other quantum numbers compared to their corresponding quarks. Antistrange quark pairs with the strange quark (s) to form mesons, baryons, and other hadrons, which are the building blocks of matter in the universe.
Quantum Numbers:
Electric Charge (Q): -1/3 (negative one-third elementary charge)
Baryon Number (B): 0
Strangeness (S): 0 (antistrange quark cancels the strangeness of the strange quark)
Isospin (I3): 0 (no isospin, as it is a scalar particle)
Spin (S): 1/2 (intrinsic angular momentum)
Mass and Energy:
The antistrange quark has a mass of around 100 MeV/c² (Mega-electronvolts per speed of light squared), which is relatively small when compared to other particles. Due to its mass-energy equivalence, it carries an energy proportional to its mass, according to Einstein's famous equation, E=mc².
Quantum Mechanics:
In the framework of quantum mechanics, the antistrange quark can be described as a point particle with quantized properties such as spin and charge. Its wave function represents the probability distribution of finding the quark at a particular position in space and time. The quantum state of the quark is described by a combination of its quantum numbers.
Quantum Field Theory:
Antistrange quarks are incorporated into the Standard Model of particle physics, which is a quantum field theory. In this framework, the antistrange quark is considered a constituent of the quark field. Quantum field theory describes particles as excited states of their respective fields.
Color Charge:
Quarks, including antistrange quarks, possess a "color charge," which is a property related to the strong nuclear force (quantum chromodynamics, QCD). Unlike electric charge, which can be positive or negative, color charge comes in three types: red, green, and blue (plus their corresponding anticolors - antired, antigreen, and antiblue). Antistrange quarks carry the anticolor corresponding to the strange quark's color charge.
Strong Force Interaction:
Antistrange quarks interact through the strong nuclear force, which is mediated by gluons. The strong force binds quarks together to form hadrons like mesons and baryons. This force becomes stronger as quarks move apart, leading to the phenomenon of confinement, which prevents isolated quarks from existing in nature.
Hadron Formation:
Antistrange quarks can combine with other quarks to form hadrons. For example, a meson called K+ (kaon) consists of an antistrange quark (s̅) and an up quark (u). Baryons like Λ (lambda) can also contain an antistrange quark, combined with other quarks.
Combinations with anti strange quarks
Mesons:
K+ (Kaon): Consists of an antistrange quark (s̅) and an up quark (u).
K0 (K-meson): A neutral kaon meson that can be a mixture of both K0 and K0-bar (antikaon). It involves s̅ and s quarks in various combinations.
The D+ meson consist of a charm quark combined with a antistrange quark
Baryons
Λ (Lambda): Contains an antistrange quark (s̅), an up quark (u), and a down quark (d).
Σ (Sigma) Baryons: Various sigma baryons contain antistrange quarks.
Ξ (Xi) Baryons: Xi baryons also contain antistrange quarks:
Ω- (Omega-minus): Contains s, s, s̅ quarks, making it the only known baryon with three strange quarks.
Figure 144 - Ω- (Omega-minus) Baryon
Figure 138 - K+ (Kaon)
Figure 139 - K0 Meson
Figure 140 - D0 meson
Figure 141 - Lambda baryon (Λ)
Figure 142 - Sigma Baryons Σ+, Σ- and Σ0
Figure 143 - (Xi) Baryons Ξ- and Ξ0
Creation of antistrange quarks
Antistrange quarks can be created in various high-energy particle physics processes. The creation of an antistrange quark typically involves the conversion of energy into mass via interactions governed by fundamental forces. Here are some of the possible processes for the creation of an antistrange quark:
Pair Production: Antistrange quarks can be created through pair production, which is a common phenomenon in particle physics. In the presence of a high-energy photon or another particle, such as a gluon, with sufficient energy, an antistrange quark-antiquark pair (s̅s) can be generated from the vacuum. This process follows Einstein's famous equation, E=mc², where energy is converted into mass.
Following is an example of gluon fusion.
Collisions in Particle Accelerators: Antistrange quarks can be produced in particle accelerators, such as the Large Hadron Collider (LHC). In these experiments, high-energy protons or other particles are accelerated to nearly the speed of light and then collided with a target or with each other. The extreme energies involved in these collisions can create a variety of new particles, including antistrange quarks, through the conversion of kinetic energy into mass.
Strong Force Interactions: The strong nuclear force, described by quantum chromodynamics (QCD), can also create antistrange quarks. In processes like hadronization, quarks and gluons interact to form hadrons, which can contain antistrange quarks. These interactions are responsible for the creation of mesons and baryons, which are made up of quark-antiquark pairs or three quarks, respectively.
Decay of Heavier Particles: Some heavier particles, such as certain B mesons (containing a bottom quark), can undergo decay processes that produce antistrange quarks among their decay products. For example, a B meson may decay into a K meson (containing an antistrange quark) and other particles.
High-Energy Cosmic Rays: Cosmic rays, high-energy particles originating from space, can interact with particles in Earth's atmosphere, leading to the creation of various particles, including antistrange quarks.
Quark-Gluon Plasma: In extreme conditions of temperature and energy, such as those believed to have existed in the early universe shortly after the Big Bang, a state of matter known as quark-gluon plasma can be formed. In this state, quarks and gluons are not confined within hadrons and can freely interact, leading to the creation of quark-antiquark pairs, including antistrange quarks.
Quark-Gluon Plasma: In extreme conditions of temperature and energy, such as those believed to have existed in the early universe shortly after the Big Bang, a state of matter known as quark-gluon plasma can be formed. In this state, quarks and gluons are not confined within hadrons and can freely interact, leading to the creation of quark-antiquark pairs, including antistrange quarks.
Figure 145 - gluon fusion
Decay of antistrange quarks
Weak Decays: Antistrange quarks can undergo weak decays mediated by the weak force, which is one of the fundamental forces in particle physics. In weak decays, antistrange quarks transform into other quarks or leptons (such as electrons, muons, or tau particles) through the exchange of W and Z bosons. For example, an antistrange quark can decay into an anti-up quark (s̄ → ū), along with the emission of a W- boson, which subsequently decays into an electron and an electron antineutrino.
Kaon Decays: Antistrange quarks are often found in hadrons like kaons (K mesons), which contain one strange quark and one antistrange quark. Kaons can undergo various decay processes, leading to the transformation of antistrange quarks. For instance, a neutral kaon (K0) can decay into two pions (π+ and π-) or into a pion and an eta meson (π0 and η). These decay processes involve the transformation of the antistrange quark into other quarks, such as up (u) and antidown (d ̅ ) quarks.
Lepton Production: Antistrange quarks can participate in processes that result in the production of leptons. For example, in weak decays involving strange or antistrange quarks, muons (μ-) or tau particles (τ-) can be produced. These processes are characterized by the transformation of strange or antistrange quarks into lighter quarks, such as up or down quarks, along with the emission of W bosons.
Figure 146 - antistrange quark decay
Figure 147 - K0 decay
Annihilation of antistrange quarks
Antistrange quarks (s̄) can undergo annihilation processes when they come into contact with their corresponding strange quarks (s) or other quarks of opposite charge. Annihilation is a fundamental process in particle physics where a quark and an antiquark annihilate each other, converting their mass into energy, typically resulting in the creation of other particles. The different annihilation processes involving antistrange quarks include:
S-Quark Annihilation: Antistrange quarks (s̄) can annihilate with strange quarks (s) to produce various particles. For example, an s̄ quark and an s quark can annihilate to create vector mesons like phi mesons (Φ), which are composed of s and s̄ quarks. This process is represented as s̄ + s → Φ.
Annihilation into Pions: Antistrange quarks can also annihilate with their corresponding strange quarks to produce pions (π±, π0). Pions are mesons consisting of an up and a down quark or their antiparticles. The annihilation process can be s̄ + s → π+ or s̄ + s → π0, resulting in the formation of pions.
Hyperon Annihilation: Antistrange quarks in hyperons can undergo annihilation processes as well. For instance, in the decay of the Ξ (Xi) hyperon, which contains a strange quark and an antistrange quark, annihilation can occur, leading to the production of other particles like neutral pions (π0).
Annihilation into Leptons: In certain contexts, annihilation of antistrange quarks can also lead to the creation of leptons, such as muons (μ-) or tau particles (τ-). The annihilation typically occurs in weak interactions, with the transformation of quark-antiquark pairs into leptons, mediated by the exchange of W or Z bosons.
Annihilation in Heavy Mesons: Antistrange quarks often appear in heavy mesons like D mesons (charmed mesons) and B mesons (bottom mesons). These mesons can undergo annihilation processes where the antistrange quark annihilates with other quarks within the meson, leading to the creation of lighter mesons or other particles.
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