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The bottom quark is a third-generation quark
Quark

Quarks are a type of elementary particle and major constituents of matter. They are the only particles in the Standard Model to experience all four fundamental interaction, which are also known as fundamental interactions....
 with a charge of -e
Elementary charge

The elementary charge, usually denoted e, is the electric charge carried by a single proton, or equivalently, the negative of the electric charge carried by a single electron....
. Although all quarks are described in a similar way by the quantum chromodynamics
Quantum chromodynamics

Quantum chromodynamics is a theory of the strong interaction , a fundamental force describing the interactions of the quarks and gluons making up hadrons ....
, the bottom quark's large mass (around 4,200 MeV
MEV

MeV and meV are Multiple of the electron volt unit referring to 1,000,000 eV and 0.001 eV, respectively.Mev or MEV may refer to:...
, a bit more than four times the mass of a proton
Proton

The proton is a subatomic particle with an electric charge of +1 elementary charge. It is found in the nucleus of each atom but is also stable by itself and has a second identity as the hydrogen ion, H+....
), combined with low values of the CKM matrix
CKM Matrix

#REDIRECTCabibbo?Kobayashi?Maskawa matrix...
 elements Vub and Vcb, gives it a distinctive signature that makes it relatively easy to identify experimentally (using a technique called B-tagging
B-tagging

b-tagging is an example of a particle jet flavor tagging method used in modern high energy particle physics experiments. It is the identification of jets originating from bottom quarks ....
).






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The bottom quark is a third-generation quark
Quark

Quarks are a type of elementary particle and major constituents of matter. They are the only particles in the Standard Model to experience all four fundamental interaction, which are also known as fundamental interactions....
 with a charge of -e
Elementary charge

The elementary charge, usually denoted e, is the electric charge carried by a single proton, or equivalently, the negative of the electric charge carried by a single electron....
. Although all quarks are described in a similar way by the quantum chromodynamics
Quantum chromodynamics

Quantum chromodynamics is a theory of the strong interaction , a fundamental force describing the interactions of the quarks and gluons making up hadrons ....
, the bottom quark's large mass (around 4,200 MeV
MEV

MeV and meV are Multiple of the electron volt unit referring to 1,000,000 eV and 0.001 eV, respectively.Mev or MEV may refer to:...
, a bit more than four times the mass of a proton
Proton

The proton is a subatomic particle with an electric charge of +1 elementary charge. It is found in the nucleus of each atom but is also stable by itself and has a second identity as the hydrogen ion, H+....
), combined with low values of the CKM matrix
CKM Matrix

#REDIRECTCabibbo?Kobayashi?Maskawa matrix...
 elements Vub and Vcb, gives it a distinctive signature that makes it relatively easy to identify experimentally (using a technique called B-tagging
B-tagging

b-tagging is an example of a particle jet flavor tagging method used in modern high energy particle physics experiments. It is the identification of jets originating from bottom quarks ....
). Because three generations of quark are required for CP violation
CP violation

In particle physics, CP violation is a violation of the postulated CP symmetry, the combination of C symmetry and P symmetry. CP symmetry states that the laws of physics should be the same if a particle is interchanged with its antiparticle , and left and right were swapped ....
 (see CKM matrix), mesons containing the bottom quark are the easiest particles to use to investigate the phenomenon; such experiments are being performed at BaBar
BaBar experiment

The BaBar experiment, or simply BaBar, is an international collaboration of more than 500 physicists and engineers studying the subatomic world at energies of approximately ten times the rest mass of a proton ....
 and Belle
Belle experiment

The Belle experiment is a particle physics experiment conducted by the Belle Collaboration, an international collaboration of more than 400 physicists and engineers investigating CP-symmetry effects at the High Energy particle accelerator Research Organisation in Tsukuba, Ibaraki Prefecture, Japan....
. The bottom quark is also notable because it is a product in almost all top quark
Top quark

The top quark is the third-generation up-type quark with a charge of +elementary charge. It was discovered in 1995 by the Collider Detector at Fermilab and D0 experiment experiments at Fermilab, and is the most massive of known elementary particles....
 decays, and would be a frequent decay product for the hypothetical Higgs boson
Higgs boson

In particle physics, the Higgs boson is a massive Scalar field theory elementary particle predicted to exist by the Standard Model.The Higgs boson is the only Standard Model particle that has not yet been observed....
 if it is sufficiently light.

The bottom quark was discovered by the E288 experiment at Fermilab
Fermilab

Fermi National Accelerator Laboratory , located in Batavia, Illinois near Chicago, Illinois, is a U.S. United States Department of Energy United States Department of Energy National Labs specializing in high-energy particle physics....
 in 1977 when collisions produced bottomonium. On its discovery, there were efforts to name it "beauty", paired along with "truth", but they came to be called "bottom" and "top" instead.

The bottom quark can decay into either an up or charm quark via the weak interaction
Weak interaction

The weak interaction is one of the four fundamental interactions of nature. In the Standard Model of particle physics, it is due to the exchange of the heavy W and Z bosons....
. Both these decays are suppressed by CKM matrix, making lifetimes of most bottom particles (~10-12 s) somewhat higher than those of charmed particles (several times 10-13 s), but lower than those of strange particles (~10-10–10-8 s).

Hadrons containing bottom quarks

Some of the hadrons containing bottom quarks include:
  • B meson
    B meson

    B mesons are mesons composed of a bottom quark antiquark and either an up quark , down quark , strange quark or charm quark quark . The combination of a bottom antiquark and a top quark is not thought to be possible because of the top quark's short lifetime....
    s contain a bottom quark (or its antiparticle
    Antiparticle

    Corresponding to most kinds of particle physics, there is an associated antiparticle with the same mass and opposite electric charge. For example, the antiparticle of the electron is the positively charged antielectron, or positron, which is produced naturally in certain types of radioactive decay....
    ) and an up
    Up quark

    The up quark is a particle described by the Standard Model theory of physics. It is a first-generation quark with a charge of +elementary charge....
     or down quark
    Down quark

    The down quark is a first-generation quark with a charge of - elementary charge. It is the second-lightest of all the six flavour of quarks, the lightest being the up quark....
    .
  • and mesons contain a bottom quark along with a charm quark
    Charm quark

    The charm quark is a second-generation quark with an electric charge of + elementary charge. It is the third most massive of the quarks, at about ....
     or strange quark
    Strange quark

    The strange quark is a second-generation quark with a charge of −elementary charge and a strangeness of −1. It is the third-lightest quark after the up quark and down quarks, with a mass of somewhere between 80 and 130 MeV....
     respectively.
  • There are many bottomonium states, for example the meson. These consist of a bottom quark and its antiparticle.
  • Bottom baryon
    Baryon

    Baryons are the family of composite particle subatomic particle made of three quarks, as opposed to the mesons which are the family of composite particles made of one quark and one antiquark....
    s have been observed, and are named in analogy with strange baryons (e.g. ).


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