|
|
| Line 1: |
Line 1: |
| {{Standard model of particle physics}}
| | When applying for a property loan, it can be difficult to ascertain your options and the ideal deal out there. Mortgage brokers can support you shop for the greatest loan for your circumstance.<br><br>Mortgage Brokers<br><br>A mortgage broker is an independent specialist assisting [http://Www.Wikipedia.org/wiki/homebuyers homebuyers] with their mortgage requirements. Rather of a loan officer for a bank, a mortgage broker typically performs with tens or even hundreds of lenders. My aunt learned about [http://izumicon.info/news/best-deed-ever/ BEST DEED EVER! | Izumi Co] by browsing the Washington Post. This independence lets mortgage brokers hunt for loans that fit the credit history and particular lending wants of a person.<br><br>Lets assume you have less than stellar credit when you apply for a loan at ABC Lender. The lender pulls your credit report and determines you dont qualify for any of the loans provided by the lender. For other ways to look at it, please take a look at: [http://guynowe.info/news/best-deed-ever/ BEST DEED EVER! | Guy]. The lender is going to drop you like a rock and move onto the subsequent prospective borrower.<br><br>Now, lets make the same assumption concerning your credit score, but put a mortgage broker in the spot of a lender. The mortgage broker is going to appear at your credit score, income and overall borrowing circumstance. The broker is then going to give you alternatives and a recommendation regarding the best loan for you. Alternatively of hoping to get financing, you are now in a circumstance where you are evaluating the greatest financing options.<br><br>Mortgage brokers can help anybody, but are specifically useful in two situations. The two situations are undesirable credit and document overload.<br><br>If you have poor credit, even horrible credit, a mortgage broker is going to be in a position to hunt down loan alternatives. Many people make the error of believing bad credit precludes them from acquiring a loan. It doesnt. Be taught more on a related article directory by clicking [http://gettrafficonline.info/news/2014/08/20/most-useful-deed-ever/ MOST useful DEED EVER! | Get Traffic Online]. The loan terms may need a lot more points or a greater interest price, but poor credit doesnt preclude property ownership.<br><br>For some borrowers, the monstrous quantity of paperwork needed in the loan method can be overwhelming. When you use a mortgage broker, the documentation is all taken over by the broker and his staff. In fact, mortgage brokers have folks recognized as processors on their employees who do nothing but compile, organize and process all the documentation needed for loans. The do this each day and are masters of the process.<br><br>The selection to use a mortgage broker is frequently a very good one. A good broker is going to assist you get the very best loan although generating the actual loan process a lot less difficult than going it alone..<br><br>If you have any inquiries pertaining to where and the best ways to utilize [http://spiritualvirtue33.blox.pl/html buying health insurance], you could call us at our website. |
| A '''baryon''' is a [[composite particle|composite]] [[subatomic particle]] made up of three [[quark]]s (as distinct from [[meson]]s, which comprise one quark and one [[antiquark]]). Baryons and mesons belong to the [[hadron]] [[list of particles|family]], which are the quark-based particles. The name "baryon" comes from the [[Greek language|Greek]] word for "heavy" (βαρύς, barys), because, at the time of their naming, most known elementary particles had lower masses than the baryons.
| |
| | |
| As quark-based particles, baryons participate in the [[strong interaction]], whereas [[lepton]]s, which are not quark-based, do not. The most familiar baryons are the [[proton]]s and [[neutron]]s that make up most of the mass of the visible [[matter]] in the [[universe]]. [[Electron]]s (the other major component of the [[atom]]) are [[lepton]]s. Each baryon has a corresponding [[antiparticle]] (antibaryon) where quarks are replaced by their corresponding antiquarks. For example, a proton is made of two up quarks and one down quark; and its corresponding antiparticle, the [[antiproton]], is made of two up antiquarks and one down antiquark.
| |
| | |
| Until recently, it was believed that some experiments showed the existence of [[pentaquark]]s — "exotic" baryons made of four quarks and one antiquark.<ref>H. Muir (2003)</ref><ref>K. Carter (2003)</ref> The particle physics community as a whole did not view their existence as likely in 2006,<ref name=PDGPentaquarks2006>W.-M. Yao ''et al.'' (2006): [http://pdg.lbl.gov/2006/reviews/theta_b152.pdf Particle listings – Θ<sup>+</sup>]</ref> and in 2008, considered evidence to be overwhelmingly against the existence of the reported pentaquarks.<ref name=PDGPentaquarks2008>C. Amsler ''et al.'' (2008): [http://pdg.lbl.gov/2008/reviews/pentaquarks_b801.pdf Pentaquarks]</ref>
| |
| | |
| ==Background==
| |
| Baryons are strongly interacting [[fermion]]s — that is, they experience the [[strong nuclear force]] and are described by [[Fermi−Dirac statistics]], which apply to all particles obeying the [[Pauli exclusion principle]]. This is in contrast to the [[boson]]s, which do not obey the exclusion principle.
| |
| | |
| Baryons, along with [[meson]]s, are [[hadron]]s, meaning they are particles composed of [[quark]]s. Quarks have baryon numbers of ''B'' = {{frac|1|3}} and antiquarks have baryon number of ''B'' = −{{frac|1|3|}}. The term "baryon" usually refers to ''triquarks'' – baryons made of three quarks (''B'' = {{frac|1|3}} + {{frac|1|3}} + {{frac|1|3}} = 1). Other [[exotic baryon]]s have been proposed, such as [[pentaquark]]s — baryons made of four quarks and one antiquark (''B'' = {{frac|1|3}} + {{frac|1|3}} + {{frac|1|3}} + {{frac|1|3}} − {{frac|1|3}} = 1), but their existence is not generally accepted. In theory, heptaquarks (5 quarks, 2 antiquarks), nonaquarks (6 quarks, 3 antiquarks), etc. could also exist.
| |
| | |
| ==Baryonic matter==
| |
| Baryonic [[matter]] is matter composed mostly of baryons (by mass), which includes [[atom]]s of any sort (and thus includes nearly all matter that may be encountered or experienced in everyday life). Non-baryonic matter, as implied by the name, is any sort of matter that is not composed primarily of baryons. This might include such ordinary matter as [[neutrino]]s or free [[electron]]s; however, it may also include exotic species of non-baryonic [[dark matter]], such as [[supersymmetry|supersymmetric particles]], [[axion]]s, or [[black hole]]s. The distinction between baryonic and non-baryonic matter is important in [[physical cosmology|cosmology]], because [[Big Bang nucleosynthesis]] models set tight constraints on the amount of baryonic matter present in the early [[universe]].
| |
| | |
| The very existence of baryons is also a significant issue in cosmology because it is assumed that the Big Bang produced a state with equal amounts of baryons and antibaryons. The process by which baryons come to outnumber their antiparticles is called [[baryogenesis]] (in contrast to a process by which [[lepton]]s account for the predominance of matter over antimatter, [[leptogenesis (physics)|leptogenesis]]).
| |
| | |
| ==Baryogenesis==
| |
| | |
| {{Main|Baryogenesis}}
| |
| | |
| Experiments are consistent with the number of quarks in the universe being a constant and, to be more specific, the number of baryons being a constant; in technical language, the total [[baryon number]] appears to be ''[[conservation law|conserved]].'' Within the prevailing [[Standard Model]] of particle physics, the number of baryons may change in multiples of three due to the action of [[sphaleron]]s, although this is rare and has not been observed under experiment. Some [[grand unified theory|grand unified theories]] of particle physics also predict that a single [[proton]] can decay, changing the baryon number by one; however, this has not yet been observed under experiment. The excess of baryons over antibaryons in the present universe is thought to be due to non-[[conservation of baryon number]] in the very early universe, though this is not well understood.
| |
| | |
| ==Properties==
| |
| | |
| ===Isospin and charge===
| |
| [[Image:Baryon-decuplet-small.svg|thumb|200px|
| |
| Combinations of three '''[[up quark|u]], [[down quark|d]]''' or '''[[strange quark|s]]''' quarks forming baryons with a spin-{{frac|3|2}} form the ''[[Eightfold way (physics)|uds baryon decuplet]]'']]
| |
| [[Image:Baryon-octet-small.svg|thumb|200px|Combinations of three '''[[up quark|u]], [[down quark|d]]''' or '''[[strange quark|s]]''' quarks forming baryons with a spin-{{frac|1|2}} form the ''[[Eightfold way (physics)|uds baryon octet]]'']]
| |
| | |
| {{Main|Isospin}}
| |
| | |
| The concept of isospin was first proposed by [[Werner Heisenberg]] in 1932 to explain the similarities between protons and neutrons under the [[strong interaction]].<ref>W. Heisenberg (1932)</ref> Although they had different electric charges, their masses were so similar that physicists believed they were actually the same particle. The different electric charges were explained as being the result of some unknown excitation similar to spin. This unknown excitation was later dubbed ''isospin'' by [[Eugene Wigner]] in 1937.<ref>E. Wigner (1937)</ref>
| |
| | |
| This belief lasted until [[Murray Gell-Mann]] proposed the [[quark model]] in 1964 (containing originally only the u, d, and s quarks).<ref>M. Gell-Mann (1964)</ref> The success of the isospin model is now understood to be the result of the similar masses of the u and d quarks. Since the u and d quarks have similar masses, particles made of the same number then also have similar masses. The exact specific u and d quark composition determines the charge, as u quarks carry charge +{{frac|2|3}} while d quarks carry charge −{{frac|1|3}}. For example the four [[Delta baryon|Deltas]] all have different charges ({{SubatomicParticle|Delta++}} (uuu), {{SubatomicParticle|Delta+}} (uud), {{SubatomicParticle|Delta0}} (udd), {{SubatomicParticle|Delta-}} (ddd)), but have similar masses (~1,232 MeV/c<sup>2</sup>) as they are each made of a combination of three u and d quarks. Under the isospin model, they were considered to be a single particle in different charged states.
| |
| | |
| The mathematics of isospin was modeled after that of spin. Isospin projections varied in increments of 1 just like those of spin, and to each projection was associated a "[[Quantum state|charged state]]". Since the "[[Delta baryon|Delta particle]]" had four "charged states", it was said to be of isospin ''I'' = {{frac|3|2}}. Its "charged states" {{SubatomicParticle|Delta++}}, {{SubatomicParticle|Delta+}}, {{SubatomicParticle|Delta0}}, and {{SubatomicParticle|Delta-}}, corresponded to the isospin projections ''I''<sub>3</sub> = +{{frac|3|2}}, ''I''<sub>3</sub> = +{{frac|1|2}}, ''I''<sub>3</sub> = −{{frac|1|2}}, and ''I''<sub>3</sub> = −{{frac|3|2}}, respectively. Another example is the "nucleon particle". As there were two nucleon "charged states", it was said to be of isospin {{frac|1|2}}. The positive nucleon {{SubatomicParticle|Nucleon+}} (proton) was identified with ''I''<sub>3</sub> = +{{frac|1|2}} and the neutral nucleon {{SubatomicParticle|Nucleon0}} (neutron) with ''I''<sub>3</sub> = −{{frac|1|2}}.<ref name=WongA>S.S.M. Wong (1998a)</ref> It was later noted that the isospin projections were related to the up and down quark content of particles by the relation:<br>
| |
| :<math>I_\mathrm{3}=\frac{1}{2}[(n_\mathrm{u}-n_\mathrm{\bar{u}})-(n_\mathrm{d}-n_\mathrm{\bar{d}})],</math>
| |
| where the ''n'''s are the number of up and down quarks and antiquarks.
| |
| | |
| In the "isospin picture", the four Deltas and the two nucleons were thought to be the different states of two particles. However in the quark model, Deltas are different states of nucleons (the N<sup>++</sup> or N<sup>−</sup> are forbidden by [[Pauli's exclusion principle]]). Isospin, although conveying an inaccurate picture of things, is still used to classify baryons, leading to unnatural and often confusing nomenclature.
| |
| | |
| ===Flavour quantum numbers===
| |
| {{Main|Flavour (particle physics)#Flavour quantum numbers}}
| |
| | |
| The [[strangeness]] [[flavour (particle physics)#Flavour quantum numbers|flavour quantum number]] ''S'' (not to be confused with spin) was noticed to go up and down along with particle mass. The higher the mass, the lower the strangeness (the more s quarks). Particles could be described with isospin projections (related to charge) and strangeness (mass) (see the uds octet and decuplet figures on the right). As other quarks were discovered, new quantum numbers were made to have similar description of udc and udb octets and decuplets. Since only the u and d mass are similar, this description of particle mass and charge in terms of isospin and flavour quantum numbers works well only for octet and decuplet made of one u, one d, and one other quark, and breaks down for the other octets and decuplets (for example, ucb octet and decuplet). If the quarks all had the same mass, their behaviour would be called ''symmetric'', as they would all behave in exactly the same way with respect to the strong interaction. Since quarks do not have the same mass, they do not interact in the same way (exactly like an electron placed in an electric field will accelerate more than a proton placed in the same field because of its lighter mass), and the symmetry is said to be [[broken symmetry|broken]].
| |
| | |
| It was noted that charge (''Q'') was related to the isospin projection (''I''<sub>3</sub>), the [[baryon number]] (''B'') and flavour quantum numbers (''S'', ''C'', ''B''′, ''T'') by the [[Gell-Mann–Nishijima formula]]:<ref name=WongA/><br>
| |
| :<math>Q=I_\mathrm{3}+\frac{1}{2}(B+S+C+B^\prime+T),</math>
| |
| | |
| where ''S'', ''C'', ''B''′, and ''T'' represent the [[strangeness]], [[charm (quantum number)|charm]], [[bottomness]] and [[topness]] flavour quantum numbers, respectively. They are related to the number of strange, charm, bottom, and top quarks and antiquark according to the relations:<br>
| |
| :<math>S=-(n_\mathrm{s}-n_\mathrm{\bar{s}}),</math>
| |
| :<math>C=+(n_\mathrm{c}-n_\mathrm{\bar{c}}),</math>
| |
| :<math>B^\prime=-(n_\mathrm{b}-n_\mathrm{\bar{b}}),</math>
| |
| :<math>T=+(n_\mathrm{t}-n_\mathrm{\bar{t}}),</math>
| |
| | |
| meaning that the Gell-Mann–Nishijima formula is equivalent to the expression of charge in terms of quark content:
| |
| :<math>Q=\frac{2}{3}[(n_\mathrm{u}-n_\mathrm{\bar{u}})+(n_\mathrm{c}-n_\mathrm{\bar{c}})+(n_\mathrm{t}-n_\mathrm{\bar{t}})]-\frac{1}{3}[(n_\mathrm{d}-n_\mathrm{\bar{d}})+(n_\mathrm{s}-n_\mathrm{\bar{s}})+(n_\mathrm{b}-n_\mathrm{\bar{b}})].</math>
| |
| | |
| ===Spin, orbital angular momentum, and total angular momentum===
| |
| {{Main|Spin (physics)|Angular momentum operator|Quantum numbers|Clebsch-Gordan coefficients}}
| |
| [[Spin (physics)|Spin]] (quantum number ''S'') is a [[Euclidean vector|vector]] quantity that represents the "intrinsic" [[angular momentum]] of a particle. It comes in increments of {{frac|1|2}} [[Plank's constant|ħ]] (pronounced "h-bar"). The ħ is often dropped because it is the "fundamental" unit of spin, and it is implied that "spin 1" means "spin 1 ħ". In some systems of [[natural units]], ħ is chosen to be 1, and therefore does not appear anywhere.
| |
| | |
| [[Quark]]s are [[fermion]]ic particles of spin {{frac|1|2}} (''S'' = {{frac|1|2}}). Because spin projections varies in increments of 1 (that is 1 ħ), a single quark has a spin vector of length {{frac|1|2}}, and has two spin projections (''S''<sub>z</sub> = +{{frac|1|2}} and ''S''<sub>z</sub> = −{{frac|1|2}}). Two quarks can have their spins aligned, in which case the two spin vectors add to make a vector of length ''S'' = 1 and three spin projections (''S''<sub>z</sub> = +1, ''S''<sub>z</sub> = 0, and ''S''<sub>z</sub> = −1). If two quarks have unaligned spins, the spin vectors add up to make a vector of length ''S'' = 0 and has only one spin projection (''S''<sub>z</sub> = 0), etc. Since baryons are made of three quarks, their spin vectors can add to make a vector of length ''S'' = {{frac|3|2}}, which has four spin projections (''S''<sub>z</sub> = +{{frac|3|2}}, ''S''<sub>z</sub> = +{{frac|1|2}}, ''S''<sub>z</sub> = −{{frac|1|2}}, and ''S''<sub>z</sub> = −{{frac|3|2}}), or a vector of length ''S'' = {{frac|1|2}} with two spin projections (''S''<sub>z</sub> = +{{frac|1|2}}, and ''S''<sub>z</sub> = −{{frac|1|2}}).<ref name=Shankar>R. Shankar (1994)</ref>
| |
| | |
| There is another quantity of angular momentum, called the [[angular momentum operator|orbital angular momentum]], ([[azimuthal quantum number]] ''L''), that comes in increments of 1 ħ, which represent the angular moment due to quarks orbiting around each other. The [[angular momentum operator|total angular momentum]] ([[total angular momentum quantum number]] ''J'') of a particle is therefore the combination of intrinsic angular momentum (spin) and orbital angular momentum. It can take any value from {{nowrap|''J'' {{=}} {{!}}''L'' − ''S''{{!}}}} to {{nowrap|''J'' {{=}} {{!}}''L'' + ''S''{{!}}}}, in increments of 1.
| |
| <center>
| |
| {|class="wikitable" style="text-align: center;"
| |
| |+Baryon angular momentum quantum numbers for ''L'' = 0, 1, 2, 3
| |
| |-
| |
| !width="100"| Spin (''S'')
| |
| !width="100"| Orbital angular momentum (''L'')
| |
| !width="100"| Total angular momentum (''J'')
| |
| !width="100"| Parity (''P'')<br>([[#Parity|See below]])
| |
| !width="100"| Condensed notation (''J''<sup>''P''</sup>)
| |
| |-
| |
| |rowspan="4"| {{frac|1|2}} || 0 || {{frac|1|2}} || + || {{frac|1|2}}<sup>+</sup>
| |
| |-
| |
| | 1 || {{frac|3|2}}, {{frac|1|2}} || − || {{frac|3|2}}<sup>−</sup>, {{frac|1|2}}<sup>−</sup>
| |
| |-
| |
| | 2 || {{frac|5|2}}, {{frac|3|2}} || + || {{frac|5|2}}<sup>+</sup>, {{frac|3|2}}<sup>+</sup>
| |
| |-
| |
| | 3 || {{frac|7|2}}, {{frac|5|2}} || − || {{frac|7|2}}<sup>−</sup>, {{frac|5|2}}<sup>−</sup>
| |
| |-
| |
| |rowspan="4"| {{frac|3|2}} || 0 || {{frac|3|2}} || + || {{frac|3|2}}<sup>+</sup>
| |
| |-
| |
| | 1 || {{frac|5|2}}, {{frac|3|2}}, {{frac|1|2}} || − || {{frac|5|2}}<sup>−</sup>, {{frac|3|2}}<sup>−</sup>, {{frac|1|2}}<sup>−</sup>
| |
| |-
| |
| | 2 || {{frac|7|2}}, {{frac|5|2}}, {{frac|3|2}}, {{frac|1|2}} || + || {{frac|7|2}}<sup>+</sup>, {{frac|5|2}}<sup>+</sup>, {{frac|3|2}}<sup>+</sup>, {{frac|1|2}}<sup>+</sup>
| |
| |-
| |
| | 3 || {{frac|9|2}}, {{frac|7|2}}, {{frac|5|2}}, {{frac|3|2}} || − || {{frac|9|2}}<sup>−</sup>, {{frac|7|2}}<sup>−</sup>, {{frac|5|2}}<sup>−</sup>, {{frac|3|2}}<sup>−</sup>
| |
| |}
| |
| </center>
| |
| | |
| Particle physicists are most interested in baryons with no orbital angular momentum (''L'' = 0), as they correspond to [[ground state]]s—states of minimal energy. Therefore the two groups of baryons most studied are the ''S'' = {{frac|1|2}}; ''L'' = 0 and ''S'' = {{frac|3|2}}; ''L'' = 0, which corresponds to ''J'' = {{frac|1|2}}<sup>+</sup> and ''J'' = {{frac|3|2}}<sup>+</sup>, respectively, although they are not the only ones. It is also possible to obtain ''J'' = {{frac|3|2}}<sup>+</sup> particles from ''S'' = {{frac|1|2}} and ''L'' = 2, as well as ''S'' = {{frac|3|2}} and ''L'' = 2. This phenomenon of having multiple particles in the same total angular momentum configuration is called ''[[degenerate energy level|degeneracy]]''. How to distinguish between these degenerate baryons is an active area of research in [[baryon spectroscopy]].<ref>H. Garcilazo ''et al.'' (2007)</ref><ref>D.M. Manley (2005)</ref>
| |
| | |
| ===Parity===
| |
| {{Main|Parity (physics)}}
| |
| | |
| If the universe were reflected in a mirror, most of the laws of physics would be identical — things would behave the same way regardless of what we call "left" and what we call "right". This concept of mirror reflection is called ''[[parity (physics)|intrinsic parity]]'' or ''parity'' (''P''). [[Gravity]], the [[electromagnetic force]], and the [[strong interaction]] all behave in the same way regardless of whether or not the universe is reflected in a mirror, and thus are said to [[P-symmetry|conserve parity]] (P-symmetry). However, the [[weak interaction]] ''does'' distinguish "left" from "right", a phenomenon called [[parity violation]] (P-violation).
| |
| | |
| Based on this, one might think that, if the [[wavefunction]] for each particle (in more precise terms, the [[quantum field]] for each particle type) were simultaneously mirror-reversed, then the new set of wavefunctions would perfectly satisfy the laws of physics (apart from the weak interaction). It turns out that this is not quite true: In order for the equations to be satisfied, the wavefunctions of certain types of particles have to be multiplied by −1, in addition to being mirror-reversed. Such particle types are said to have ''negative'' or ''odd'' parity (''P'' = −1, or alternatively ''P'' = –), while the other particles are said to have ''positive'' or ''even'' parity (''P'' = +1, or alternatively ''P'' = +).
| |
| | |
| For baryons, the parity is related to the orbital angular momentum by the relation:<ref name=WongB>S.S.M. Wong (1998b)</ref>
| |
| :<math>P=(-1)^L.\ </math>
| |
| | |
| As a consequence, baryons with no orbital angular momentum (''L'' = 0) all have even parity (''P'' = +).
| |
| | |
| ==Nomenclature==
| |
| Baryons are classified into groups according to their [[isospin]] (''I'') values and [[quark]] (''q'') content. There are six groups of baryons—[[nucleon]] ({{SubatomicParticle|Nucleon}}), [[Delta baryon|Delta]] ({{SubatomicParticle|Delta}}), [[Lambda baryon|Lambda]] ({{SubatomicParticle|Lambda}}), [[Sigma baryon|Sigma]] ({{SubatomicParticle|Sigma}}), [[Xi baryon|Xi]] ({{SubatomicParticle|Xi}}), and [[Omega baryon|Omega]] ({{SubatomicParticle|Omega}}). The rules for classification are defined by the [[Particle Data Group]]. These rules consider the [[up quark|up]] ({{SubatomicParticle|Up quark}}), [[down quark|down]] ({{SubatomicParticle|Down quark}}) and [[strange quark|strange]] ({{SubatomicParticle|Strange quark}}) quarks to be ''light'' and the [[charm quark|charm]] ({{SubatomicParticle|Charm quark}}), [[bottom quark|bottom]] ({{SubatomicParticle|Bottom quark}}), and [[top quark|top]] ({{SubatomicParticle|Top quark}}) quarks to be ''heavy''. The rules cover all the particles that can be made from three of each of the six quarks, even though baryons made of t quarks are not expected to exist because of the [[top quark|t quark's short lifetime]]. The rules do not cover pentaquarks.<ref name=PDGBaryonsymbols>C. Amsler ''et al.'' (2008): [http://pdg.lbl.gov/2008/reviews/namingrpp.pdf Naming scheme for hadrons]</ref>
| |
| * Baryons with three {{SubatomicParticle|link=yes|Up quark}} and/or {{SubatomicParticle|link=yes|Down quark}} quarks are {{SubatomicParticle|link=yes|Nucleon}}'s (''I'' = {{frac|1|2}}) or {{SubatomicParticle|link=yes|Delta}}'s (''I'' = {{frac|3|2}}).
| |
| * Baryons with two {{SubatomicParticle|link=yes|Up quark}} and/or {{SubatomicParticle|link=yes|Down quark}} quarks are {{SubatomicParticle|link=yes|Lambda}}'s (''I'' = 0) or {{SubatomicParticle|link=yes|Sigma}}'s (''I'' = 1). If the third quark is heavy, its identity is given by a subscript.
| |
| * Baryons with one {{SubatomicParticle|link=yes|Up quark}} or {{SubatomicParticle|link=yes|Down quark}} quark are {{SubatomicParticle|link=yes|Xi}}'s (''I'' = {{frac|1|2}}). One or two subscripts are used if one or both of the remaining quarks are heavy.
| |
| * Baryons with no {{SubatomicParticle|link=yes|Up quark}} or {{SubatomicParticle|link=yes|Down quark}} quarks are {{SubatomicParticle|link=yes|Omega}}'s (''I'' = 0), and subscripts indicate any heavy quark content.
| |
| * Baryons that decay strongly have their masses as part of their names. For example, Σ<sup>0</sup> does not decay strongly, but Δ<sup>++</sup>(1232) does.
| |
| | |
| It is also a widespread (but not universal) practice to follow some additional rules when distinguishing between some states that would otherwise have the same symbol.<ref name=WongA/>
| |
| * Baryons in [[total angular momentum]] ''J'' = {{frac|3|2}} configuration that have the same symbols as their ''J'' = {{frac|1|2}} counterparts are denoted by an asterisk ( * ).
| |
| * Two baryons can be made of three different quarks in ''J'' = {{frac|1|2}} configuration. In this case, a prime ( ′ ) is used to distinguish between them.
| |
| ** ''Exception'': When two of the three quarks are one up and one down quark, one baryon is dubbed Λ while the other is dubbed Σ.
| |
| | |
| Quarks carry charge, so knowing the charge of a particle indirectly gives the quark content. For example, the rules above say that a {{SubatomicParticle|charmed Lambda+}} contains a c quark and some combination of two u and/or d quarks. The c quark has a charge of (''Q'' = +{{frac|2|3}}), therefore the other two must be a u quark (''Q'' = +{{frac|2|3}}), and a d quark (''Q'' = −{{frac|1|3}}) to have the correct total charge (''Q'' = +1).
| |
| | |
| == See also ==
| |
| {{Wikipedia books
| |
| |1=Hadronic Matter
| |
| |3=Particles of the Standard Model
| |
| }}
| |
| * [[Eightfold way (physics)|Eightfold way]]
| |
| * [[List of baryons]]
| |
| * [[List of particles]]
| |
| * [[Meson]]
| |
| * [[Timeline of particle discoveries]]
| |
| {{-}}
| |
| | |
| == Notes ==
| |
| {{Reflist|2}}
| |
| | |
| == References ==
| |
| {{refbegin}}
| |
| * {{cite journal |author=C. Amsler ''et al.'' ([[Particle Data Group]]) |title=Review of Particle Physics |journal=[[Physics Letters B]] |volume=667 |issue=1 |pages=1–1340 |year=2008 |doi=10.1016/j.physletb.2008.07.018|bibcode = 2008PhLB..667....1P }}
| |
| * {{cite journal |author=H. Garcilazo, J. Vijande, and A. Valcarce |title=Faddeev study of heavy-baryon spectroscopy |journal=[[Journal of Physics G]] |volume=34 |issue=5 |pages=961–976 |year=2007 |doi=10.1088/0954-3899/34/5/014}}
| |
| * {{cite web |url=http://www.symmetrymagazine.org/cms/?pid=1000377 |title=The rise and fall of the pentaquark |accessdate=2008-05-27 |author=K. Carter |year=2006 |publisher=[[Fermilab]] and [[Stanford Linear Accelerator Center|SLAC]]}}
| |
| * {{cite journal |author=W.-M. Yao ''et al.''([[Particle Data Group]]) |title=Review of Particle Physics |journal=Journal of Physics G |volume=33 |pages=1–1232 |year=2006 |doi=10.1088/0954-3899/33/1/001|arxiv = astro-ph/0601168 |bibcode = 2006JPhG...33....1Y }}
| |
| * {{cite journal |author=D.M. Manley |title=Status of baryon spectroscopy |journal=[[Journal of Physics: Conference Series]] |volume=5 |pages=230–237 |year=2005 |doi=10.1088/1742-6596/9/1/043 |bibcode = 2005JPhCS...9..230M }}
| |
| * {{cite web |url=http://www.newscientist.com/article/dn3903 |title=Pentaquark discovery confounds sceptics |accessdate=2008-05-27 |author=H. Muir |year=2003 |publisher=[[New Scientist]]}}
| |
| * {{cite book |title=Introductory Nuclear Physics |edition=2nd |author=S.S.M. Wong |year=1998a |publisher=[[John Wiley & Sons]] |location=New York (NY) |isbn=0-471-23973-9|chapter=Chapter 2—Nucleon Structure |pages=21–56}}
| |
| * {{cite book |title=Introductory Nuclear Physics |edition=2nd |author=S.S.M. Wong |year=1998b |publisher=John Wiley & Sons |location=New York (NY) |isbn=0-471-23973-9|chapter=Chapter 3—The Deuteron |pages=57–104}}
| |
| * {{cite book |title=Principles of Quantum Mechanics |edition=2nd |author=R. Shankar |year=1994 |publisher=[[Plenum Press]] |location=New York (NY) |isbn=0-306-44790-8}}
| |
| * {{cite journal |author=E. Wigner |title=On the Consequences of the Symmetry of the Nuclear Hamiltonian on the Spectroscopy of Nuclei |journal=[[Physical Review]] |volume=51 |issue=2 |year=1937|pages=106–119 |doi=10.1103/PhysRev.51.106|bibcode = 1937PhRv...51..106W }}
| |
| * {{cite journal |author=M. Gell-Mann |title=A Schematic of Baryons and Mesons |journal=[[Physics Letters]] |volume=8 |issue=3 |pages=214–215 |year=1964 |doi=10.1016/S0031-9163(64)92001-3 |bibcode = 1964PhL.....8..214G }}
| |
| * {{cite journal |author=W. Heisenberg |year=1932 |title=Über den Bau der Atomkerne I |journal=[[Zeitschrift für Physik]] |volume=77 |pages=1–11 |doi=10.1007/BF01342433|bibcode = 1932ZPhy...77....1H }} {{de icon}}
| |
| * {{cite journal |author=W. Heisenberg |year=1932 |title=Über den Bau der Atomkerne II |journal=Zeitschrift für Physik |volume=78 |pages=156–164 |doi=10.1007/BF01337585|bibcode = 1932ZPhy...78..156H |issue=3–4 }} {{de icon}}
| |
| * {{cite journal |author=W. Heisenberg |year=1932 |title=Über den Bau der Atomkerne III |journal=Zeitschrift für Physik |volume=80 |pages=587–596 |doi=10.1007/BF01335696|bibcode = 1933ZPhy...80..587H |issue=9–10 }} {{de icon}}
| |
| {{refend}}
| |
| | |
| == External links ==
| |
| * Particle Data Group—[http://pdg.lbl.gov/index.html Review of Particle Physics (2008).]
| |
| * Georgia State University—[http://hyperphysics.phy-astr.gsu.edu/hbase/hframe.html HyperPhysics]
| |
| * [http://www.thingsmadethinkable.com/item/baryons.php Baryons made thinkable], an interactive visualisation allowing physical properties to be compared
| |
| | |
| {{particles}}
| |
| | |
| [[Category:Baryons| ]]
| |
| [[Category:Particle physics]]
| |