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33.4 Particles, patterns, and conservation laws  (Page 2/21)

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Hadrons and leptons

Particles can also be revealingly grouped according to what forces they feel between them. All particles (even those that are massless) are affected by gravity, since gravity affects the space and time in which particles exist. All charged particles are affected by the electromagnetic force, as are neutral particles that have an internal distribution of charge (such as the neutron with its magnetic moment). Special names are given to particles that feel the strong and weak nuclear forces. Hadrons are particles that feel the strong nuclear force, whereas leptons    are particles that do not. The proton, neutron, and the pions are examples of hadrons. The electron, positron, muons, and neutrinos are examples of leptons, the name meaning low mass. Leptons feel the weak nuclear force. In fact, all particles feel the weak nuclear force. This means that hadrons are distinguished by being able to feel both the strong and weak nuclear forces.

[link] lists the characteristics of some of the most important subatomic particles, including the directly observed carrier particles for the electromagnetic and weak nuclear forces, all leptons, and some hadrons. Several hints related to an underlying substructure emerge from an examination of these particle characteristics. Note that the carrier particles are called gauge bosons . First mentioned in Patterns in Spectra Reveal More Quantization , a boson    is a particle with zero or an integer value of intrinsic spin (such as s = 0, 1, 2, ... size 12{s=0,`1,`2,` "." "." "." } {} ), whereas a fermion    is a particle with a half-integer value of intrinsic spin ( s = 1 / 2, 3 / 2, . . . size 12{s=1/2,`3/2,` "." "." "." } {} ). Fermions obey the Pauli exclusion principle whereas bosons do not. All the known and conjectured carrier particles are bosons.

The upper image shows an electron and positron colliding head-on. The lower image shows a starburst image from which two photons are emerging in opposite directions.
When a particle encounters its antiparticle, they annihilate, often producing pure energy in the form of photons. In this case, an electron and a positron convert all their mass into two identical energy rays, which move away in opposite directions to keep total momentum zero as it was before. Similar annihilations occur for other combinations of a particle with its antiparticle, sometimes producing more particles while obeying all conservation laws.
Selected particle characteristics The lower of the ∓ size 12{ -+ {}} {} or ± size 12{ +- {}} {} symbols are the values for antiparticles.
Category Particle name Symbol Antiparticle Rest mass ( MeV / c 2 ) B L e L μ L τ size 12{L rSub { size 8{τ} } } {} S size 12{S} {} Lifetime Lifetimes are traditionally given as t 1 / 2 / 0 . 693 (which is 1 / λ size 12{ {1} slash {λ} } {} , the inverse of the decay constant). (s)
Gauge Photon γ size 12{γ} {} Self 0 0 0 0 0 0 Stable
Bosons W size 12{W} {} W + size 12{W rSup { size 8{+{}} } } {} W − size 12{W rSup { size 8{ - {}} } } {} 80 . 39 × 10 3 size 12{"80" "." "22" times "10" rSup { size 8{3} } } {} 0 0 0 0 0 1.6 × 10 − 25 size 12{3 times "10" rSup { size 8{ - "25"} } } {}
Z size 12{Z} {} Z 0 size 12{Z rSup { size 8{0} } } {} Self 91 . 19 × 10 3 size 12{"91" "." "19" times "10" rSup { size 8{3} } } {} 0 0 0 0 0 1.32 × 10 − 25 size 12{3 times "10" rSup { size 8{ - "25"} } } {}
Leptons Electron e − size 12{e rSup { size 8{ - {}} } } {} e + size 12{e rSup { size 8{ - {}} } } {} 0.511 0 ± 1 size 12{ +- 1} {} 0 0 0 Stable
Neutrino (e) ν e size 12{e rSup { size 8{ - {}} } } {} v ¯ e size 12{ { bar {v}} rSub { size 8{e} } } {} 0 7 . 0 eV size 12{0` left (<7 "." 0`"eV" right )} {} Neutrino masses may be zero. Experimental upper limits are given in parentheses. 0 ± 1 size 12{ +- 1} {} 0 0 0 Stable
Muon μ − size 12{μ rSup { size 8{ - {}} } } {} μ + size 12{μ rSup { size 8{+{}} } } {} 105.7 0 0 ± 1 size 12{ +- 1} {} 0 0 2 . 20 × 10 − 6 size 12{2 "." "20" times "10" rSup { size 8{ - 6} } } {}
Neutrino ( μ size 12{μ} {} ) v μ size 12{v rSub { size 8{μ} } } {} v - μ size 12{v rSub { size 8{μ} } } {} 0 ( < 0.27 ) 0 0 ± 1 size 12{ +- 1} {} 0 0 Stable
Tau τ − size 12{τ rSup { size 8{ - {}} } } {} τ + size 12{τ rSup { size 8{+{}} } } {} 1777 0 0 0 ± 1 size 12{ +- 1} {} 0 2 . 91 × 10 − 13 size 12{2 "." "29" times "10" rSup { size 8{ - "13"} } } {}
Neutrino ( τ size 12{τ} {} ) v τ size 12{v rSub { size 8{τ} } } {} v - τ size 12{ { bar {v}} rSub { size 8{τ} } } {} 0 ( < 31 ) 0 0 0 ± 1 size 12{ +- 1} {} 0 Stable
Hadrons (selected)
  Mesons Pion π + size 12{π rSup { size 8{+{}} } } {} π − size 12{π rSup { size 8{ - {}} } } {} 139.6 0 0 0 0 0 2.60 × 10 −8
π 0 size 12{π rSup { size 8{0} } } {} Self 135.0 0 0 0 0 0 8.4 × 10 −17
Kaon K + size 12{K rSup { size 8{+{}} } } {} K − size 12{K rSup { size 8{ - {}} } } {} 493.7 0 0 0 0 ± 1 size 12{ +- 1} {} 1.24 × 10 −8
K 0 size 12{K rSup { size 8{0} } } {} K - 0 size 12{ { bar {K}} rSup { size 8{0} } } {} 497.6 0 0 0 0 ± 1 size 12{ +- 1} {} 0.90 × 10 −10
Eta η 0 size 12{η rSup { size 8{0} } } {} Self 547.9 0 0 0 0 0 2.53 × 10 −19
(many other mesons known)
  Baryons Proton p size 12{p} {} p - size 12{ { bar {p}}} {} 938.3 ± 1 0 0 0 0 Stable Experimental lower limit is >5 × 10 32 size 12{>5 times "10" rSup { size 8{"32"} } } {} for proposed mode of decay.
Neutron n size 12{n} {} n - size 12{ { bar {n}}} {} 939.6 ± 1 0 0 0 0 882
Lambda Λ 0 size 12{Λ rSup { size 8{0} } } {} Λ - 0 size 12{ { bar {Λ}} rSup { size 8{0} } } {} 1115.7 ± 1 0 0 0 ∓ 1 size 12{ -+ 1} {} 2.63 × 10 −10
Sigma Σ + size 12{Σ rSup { size 8{+{}} } } {} Σ - − size 12{ { bar {Σ}} rSup { size 8{ - {}} } } {} 1189.4 ± 1 0 0 0 ∓ 1 size 12{ -+ 1} {} 0.80 × 10 −10
Σ 0 size 12{Σ rSup { size 8{0} } } {} Σ - 0 size 12{ { bar {Σ}} rSup { size 8{0} } } {} 1192.6 ± 1 0 0 0 ∓ 1 size 12{ -+ 1} {} 7.4 × 10 −20
Σ − size 12{Σ rSup { size 8{ - {}} } } {} Σ - + size 12{ { bar {Σ}} rSup { size 8{+{}} } } {} 1197.4 ± 1 0 0 0 ∓ 1 size 12{ -+ 1} {} 1.48 × 10 −10
Xi Ξ 0 size 12{Ξ rSup { size 8{0} } } {} Ξ - 0 size 12{ { bar {Ξ}} rSup { size 8{0} } } {} 1314.9 ± 1 0 0 0 ∓ 2 size 12{ -+ 2} {} 2.90 × 10 −10
Ξ − size 12{Ξ rSup { size 8{ - {}} } } {} Ξ + size 12{Ξ rSup { size 8{+{}} } } {} 1321.7 ± 1 0 0 0 ∓ 2 size 12{ -+ 2} {} 1.64 × 10 −10
Omega Ω − size 12{ %OMEGA rSup { size 8{ - {}} } } {} Ω + size 12{ %OMEGA rSup { size 8{+{}} } } {} 1672.5 ± 1 0 0 0 ∓ 3 size 12{ -+ 3} {} 0.82 × 10 −10
(many other baryons known)

Questions & Answers

Discuss the differences between taste and flavor, including how other sensory inputs contribute to our  perception of flavor.
John Reply
taste refers to your understanding of the flavor . while flavor one The other hand is refers to sort of just a blend things.
Faith
While taste primarily relies on our taste buds, flavor involves a complex interplay between taste and aroma
Kamara
which drugs can we use for ulcers
Ummi Reply
omeprazole
Kamara
what
Renee
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Renee
is a drug
Kamara
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Kamara
Omeprazole Cimetidine / Tagament For the complicated once ulcer - kit
Patrick
what is the function of lymphatic system
Nency Reply
Not really sure
Eli
to drain extracellular fluid all over the body.
asegid
The lymphatic system plays several crucial roles in the human body, functioning as a key component of the immune system and contributing to the maintenance of fluid balance. Its main functions include: 1. Immune Response: The lymphatic system produces and transports lymphocytes, which are a type of
asegid
to transport fluids fats proteins and lymphocytes to the blood stream as lymph
Adama
what is anatomy
Oyindarmola Reply
Anatomy is the identification and description of the structures of living things
Kamara
what's the difference between anatomy and physiology
Oyerinde Reply
Anatomy is the study of the structure of the body, while physiology is the study of the function of the body. Anatomy looks at the body's organs and systems, while physiology looks at how those organs and systems work together to keep the body functioning.
AI-Robot
what is enzymes all about?
Mohammed Reply
Enzymes are proteins that help speed up chemical reactions in our bodies. Enzymes are essential for digestion, liver function and much more. Too much or too little of a certain enzyme can cause health problems
Kamara
yes
Prince
how does the stomach protect itself from the damaging effects of HCl
Wulku Reply
little girl okay how does the stomach protect itself from the damaging effect of HCL
Wulku
it is because of the enzyme that the stomach produce that help the stomach from the damaging effect of HCL
Kamara
function of digestive system
Ali Reply
function of digestive
Ali
the diagram of the lungs
Adaeze Reply
what is the normal body temperature
Diya Reply
37 degrees selcius
Xolo
37°c
Stephanie
please why 37 degree selcius normal temperature
Mark
36.5
Simon
37°c
Iyogho
the normal temperature is 37°c or 98.6 °Fahrenheit is important for maintaining the homeostasis in the body the body regular this temperature through the process called thermoregulation which involves brain skin muscle and other organ working together to maintain stable internal temperature
Stephanie
37A c
Wulku
what is anaemia
Diya Reply
anaemia is the decrease in RBC count hemoglobin count and PVC count
Eniola
what is the pH of the vagina
Diya Reply
how does Lysin attack pathogens
Diya
acid
Mary
I information on anatomy position and digestive system and there enzyme
Elisha Reply
anatomy of the female external genitalia
Muhammad Reply
Organ Systems Of The Human Body (Continued) Organ Systems Of The Human Body (Continued)
Theophilus Reply
what's lochia albra
Kizito
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Source:  OpenStax, College physics. OpenStax CNX. Jul 27, 2015 Download for free at http://legacy.cnx.org/content/col11406/1.9
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