Bottom Quark
Composition :
Statistics :
Generation :
Family :
Interaction forces :
Symbol :
Antiparticle :
Mass :
Decays into :
Electric charge :
Color charge
Spin :
Weak isospin :
Weak hypercharge :
Elementary particle
Fermionic
Third
Quark
strong, weak,
electromagnetic force
gravity
b
Bottom Antiquark ( b )
4.18 GeV/c²
charm quark or
up quark
-¹/₃ e
Yes
¹/₂
LH : - ¹/₂, RH : 0
LH : + ¹/₃, RH : -²∕₃
_
+ 0.4
- 0.3
BOTTOM QUARK
Definition
The bottom quark, also known as the beauty quark (symbolized as b), is one of the six known types of quarks and is an essential component of the Standard Model of particle physics.
Quantum Numbers:
Electric Charge (Q): -1/3 (negative one-third elementary charge)
Baryon Number (B): 1/3 (one-third)
Strangeness (S): 0 (non-strange quark)
Isospin (I3): -1/2 (negative one-half)
Spin (S): 1/2 (intrinsic angular momentum)
Mass and Energy:
The bottom quark has a much larger mass than the lighter up, down, and strange quarks. Its mass is approximately 4.18 GeV/c² (Giga-electronvolts per speed of light squared). This greater mass corresponds to more energy according to Einstein's equation E=mc².
Quantum Mechanics:
In the framework of quantum mechanics, the bottom quark is considered a point-like particle with quantized properties, including its spin and charge. Its quantum state can be described by a wave function, which provides the probability distribution of finding the quark at various positions in space and time.
Quantum Field Theory:
The bottom quark is an integral part of the Standard Model of particle physics, which is described by quantum field theory. In this framework, the bottom quark is treated as a constituent of the quark field, which is a fundamental quantum field that pervades all of space. The field theory explains how quarks interact via the exchange of force-carrying particles, such as gluons (mediators of the strong nuclear force).
Strong Force Interaction:
Bottom quarks interact through the strong nuclear force, which is described by quantum chromodynamics (QCD). This interaction is responsible for binding quarks together to form hadrons, such as mesons and baryons. The strong force becomes stronger as quarks move apart, leading to the phenomenon of confinement, which means quarks are always found within larger particles and never as free particles.
Combinations with bottom quarks
Particles that contain bottom quarks (b quarks) as part of their composition are a key component of particle physics. The presence of b quarks can lead to the formation of various hadrons, especially B mesons (B-mesons) and other particles. Here's a detailed overview of some particle combinations involving bottom quarks:
B Mesons (B-Mesons):
Baryons with Bottom Quarks:
Pentaquarks with Bottom Quarks:
Tetraquarks with Bottom Quarks:
Some tetraquark states have been suggested to contain a b quark, such as the X(5568) tetraquark.
Baryons with Beauty Quarks in Exotic States
The Standard Model predicts various baryons with beauty quarks in different combinations, although not all have been observed experimentally.
Composite Mesons and Baryons
Various heavy mesons and baryons can be formed through the interaction of quarks and gluons, and some of these may contain bottom quarks.
Figure 176 - B+ Meson (B+):
Figure 177 - B0 Meson (B0)
Figure 178 - Bc+ Meson (Bc+)
Figure 179 - Lambda-b baryon (Λb)
Figure 180 - Xi-b Baryon (Ξb)
Figure 181 - Omega-b Baryon (Ωb)
Figure 182 - Pentaquark Pc(4450)+
Figure 183 - Tetraquark X(5568) includes Bottom Quark
Creation of bottom quarks
The creation of a bottom quark (also known as a b-quark or bottom quark) can occur through various processes in high-energy particle physics experiments. The bottom quark is a fundamental particle in the Standard Model, and it is typically created through the strong nuclear force interactions in high-energy particle collisions.
Quark-Quark Scattering (Gluon-Gluon Fusion)
In high-energy particle collisions, such as those that occur at particle accelerators like the Large Hadron Collider (LHC), quarks and gluons are the initial particles that participate in the interaction. The creation of a bottom quark can involve a quark-quark scattering process, mediated by the exchange of gluons. For example, in a proton-proton collision at the LHC, a bottom quark can be produced by one of the following reactions:
Gluon-gluon fusion:
Two gluons from each proton collide, and during the interaction, one of them splits into a quark-antiquark pair, one of which may be a bottom quark.
Quark-gluon scattering:
A quark from one proton and a gluon from the other proton can scatter, resulting in the creation of a bottom quark.
Resonance Production
In some cases, bottom quarks can be created as part of resonance production processes. Resonances are unstable particles that can be produced temporarily in high-energy collisions. These resonances can subsequently decay into various particles, including bottom quarks.
Electroweak Processes
While the strong nuclear force (mediated by gluons) is the primary mechanism for creating bottom quarks, electroweak processes (mediated by W and Z bosons) can also contribute, although they are less common.
Figure 186 - Bottom Quark creation via resonance
Figure 185 - Gluon-Gluon scattering creating a bottom quark
Figure 184 - Gluon-Gluon fusion resulting in creation of bottom quark
Decay of bottom quarks
The decay process of a bottom quark (also known as a b-quark or bottom quark) is an important aspect of particle physics, as it provides insights into the behavior of quarks and the fundamental interactions in the Standard Model. Bottom quarks, like other quarks, are not observed in isolation but are always confined within hadrons (composite particles) or involved in particle interactions. The decay of a bottom quark typically occurs through the weak force or strong force.
Weak Decay (Flavor-Changing Neutral Currents):
The most common decay mode of a bottom quark involves the weak nuclear force, which is responsible for changing the flavor of quarks. In these decays, the bottom quark transforms into a lighter quark, typically a charm quark, accompanied by the exchange of a W⁻ boson. This process is known as flavor-changing neutral current (FCNC) decay. The W⁻ boson subsequently decays into other particles, such as leptons or additional quarks.
In a Lambda-b baryon the bottom quark decays into a charm quark by emitting a W- boson. The W⁻ boson can further decay into various particles, including leptons and neutrinos
A bottom quark decays into a down quark by releasing a photon.
Figure 187 - A bottom quark in a Lambda Baryan decays be emitting a W- boson.
Figure 188 - botton quark decay releasing a photon
Annihilation of bottom quarks
The annihilation process of a bottom quark (b-quark or bottom quark) is not a common or prominent phenomenon in particle physics. In the context of particle physics, annihilation typically refers to the process where a particle and its corresponding antiparticle come into contact and annihilate, transforming their mass energy into other particles or radiation. However, quarks, including bottom quarks, do not typically undergo annihilation in the same way that electrons and positrons do.
Quarks, whether they are of the up-type (up, charm, top) or down-type (down, strange, bottom), are fundamental particles that are confined within hadrons (composite particles like protons and neutrons) due to the strong nuclear force, mediated by gluons. Because quarks are never found in isolation, they cannot directly annihilate with their corresponding antiparticles, as they are always in combinations of quarks and antiquarks within hadrons.
Instead, bottom quarks primarily participate in processes involving the strong nuclear force (quantum chromodynamics or QCD), where they interact with other quarks and gluons to form hadrons or take part in high-energy collisions and decays.
While there are rare processes in which quarks and antiquarks can interact and annihilate, they typically involve the exchange of multiple gluons and are much less common and less well-understood than the hadronization or decay processes that quarks typically undergo. These processes are known as "quarkonium" states, where a quark and an antiquark form a bound state, such as a meson (quark-antiquark pair), and may annihilate with time.
Fusion of bottom quarks
The fusion of bottom quarks is not a process that occurs in particle physics, and it is not a concept typically discussed in the Standard Model of particle interactions. Bottom quarks, like other quarks, primarily interact via the strong nuclear force (quantum chromodynamics or QCD) and the weak nuclear force (mediated by W and Z bosons) within the framework of the Standard Model.
Quarks are never found in isolation but are always confined within hadrons, such as mesons and baryons. The fusion, as typically understood in nuclear physics, is not applicable to quarks since they are fundamental particles and do not combine in the same way that atomic nuclei do during nuclear fusion.
The primary processes involving bottom quarks include their creation in high-energy particle collisions, their participation in strong and weak interactions, and their subsequent decays. These processes are well-studied and play a significant role in understanding the fundamental forces and particles of the Standard Model.
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