In high-energy physics, a pseudoscalar meson is a meson with total spin 0 and odd parity (usually notated as JP = 0− ).[1][a] Pseudoscalar mesons are commonly seen in proton-proton scattering and proton-antiproton annihilation, and include the pion (π), kaon (K), eta (η), and eta prime (η′) particles, whose masses are known with great precision.
The pseudoscalar mesons consisting of up, down, and strange quarks only form a nonet.
Among all of the mesons known to exist, in some sense, the pseudoscalars are the most well studied and understood.
The pion (π) was first proposed to exist by Yukawa in the 1930s as the primary force carrying boson of the Yukawa potential in nuclear interactions,[2] and was later observed at nearly the same mass that he originally predicted for it. In the 1950s and 1960s, the pseudoscalar mesons began to proliferate, and were eventually organized into a multiplet according to Murray Gell-Mann's so-called "Eightfold Way".[3]
Gell-Mann further predicted the existence of a ninth resonance in the pseudoscalar multiplet, which he originally called X. Indeed, this particle was later found and is now known as the eta prime meson (η′).[4] The structure of the pseudoscalar meson multiplet, and also the ground state baryon multiplets, led Gell-Mann (and Zweig, independently) to create the well known quark model.[5][6][7]
The η-η′ puzzleedit
Despite the pseudoscalar mesons' masses being known to high precision, and being the most well studied and understood mesons, the decay properties of the pseudoscalar mesons, particularly of eta (η) and eta-prime (η′), are somewhat contradictory to their mass hierarchy: While the η′ meson is much more massive than the η meson, the η meson is thought to contain a larger component of the relatively heavy strange and anti-strange quarks, than the η′ meson does, which appears contradictory. This failure of the quark model to explain this mass difference is called the "η-η′ puzzle".
The presence of an η(1405) state also brings glueball mixing into the discussion. It is possible that the η and η′ mesons mix with the pseudoscalar glueball which should occur somewhere above the scalar glueball in mass, as an unmixed state.[8] This is one of a few ways in which the unexpectedly large η′ mass of 957.78 MeV/c2 can be explained, relative to its model-predicted mass around 250–300 MeV/c2.
^ Compare the definition of the pseudoscalar meson to the scalar meson.
^ Because the top quark decays into a bottom quark much faster than the cloud of gluons that bind it to other quarks can assemble (a unique instance of the weak force acting more quickly than the strong force), it is currently [2021] believed that composite particles containing the top quark do not form, with the possible exception of collisions with such high energy that they have only ever occurred in the first milliseconds of the Big Bang.[9]
Referencesedit
^Qin, Wen; Zhao, Qiang; Zhong, Xian-Hui (3 May 2018). "Revisiting the pseudoscalar meson and glueball mixing and key issues in the search for pseudscalar glueball state". Physical Review D. 97 (9): 096002. arXiv:1712.02550. Bibcode:2018PhRvD..97i6002Q. doi:10.1103/PhysRevD.97.096002. S2CID 59272671.
^Yukawa, H. (1935). "On the interaction of elementary particles" (PDF). Proc. Phys.-Math. Soc. Jpn. 17 (48).
^Gell-Mann, M. (15 March 1961). "The eightfold way: A theory of strong interaction symmetry". Synchrotron Laboratory. Pasadena, CA: California Inst. of Tech. doi:10.2172/4008239. TID-12608. {{cite journal}}: Cite journal requires |journal= (help)
^Kupsc, Andrzej (2008). "What is interesting in eta and eta′ Meson decays?". AIP Conference Proceedings. 950: 165–179. arXiv:0709.0603. Bibcode:2007AIPC..950..165K. doi:10.1063/1.2819029. S2CID 15930194.
^Gell-Mann, M. (4 January 1964). "A schematic model of baryons and mesons". Physics Letters. 8 (3): 214–215. Bibcode:1964PhL.....8..214G. doi:10.1016/S0031-9163(64)92001-3.
^Zweig, G. (17 January 1964). An SU(3) model for strong interaction symmetry and its breaking (PDF) (Report). Vol. I. CERN Report No.8182/TH.401.
^Zweig, G. (1964). An SU(3) model for strong interaction symmetry and its breaking (PDF) (Report). Vol. II. CERN Report No.8419/TH.412.
^Gutsche, Thomas; Lyubovitskij, Valery E.; Tich, Malte C. (1 July 2019). "η(1405) in a chiral approach based on mixing of the pseudoscalar glueball with the first radial excitations of η and η′". Phys. Rev. D. 1 (8). doi:10.1103/PhysRevD.80.014014. S2CID 119195561.
^Fabiano, N. (1998). "Top mesons". European Physical Journal C. 2 (2): 345–350. arXiv:hep-ph/9704261. Bibcode:1998EPJC....2..345F. doi:10.1007/s100520050144. S2CID 17321939.
This particle physics–related article is a stub. You can help Wikipedia by expanding it.
pseudoscalar, meson, this, article, needs, additional, citations, verification, please, help, improve, this, article, adding, citations, reliable, sources, unsourced, material, challenged, removed, find, sources, news, newspapers, books, scholar, jstor, 2021, . This article needs additional citations for verification Please help improve this article by adding citations to reliable sources Unsourced material may be challenged and removed Find sources Pseudoscalar meson news newspapers books scholar JSTOR May 2021 Learn how and when to remove this template message In high energy physics a pseudoscalar meson is a meson with total spin 0 and odd parity usually notated as J P 0 1 a Pseudoscalar mesons are commonly seen in proton proton scattering and proton antiproton annihilation and include the pion p kaon K eta h and eta prime h particles whose masses are known with great precision The pseudoscalar mesons consisting of up down and strange quarks only form a nonet Among all of the mesons known to exist in some sense the pseudoscalars are the most well studied and understood Contents 1 History 2 The h h puzzle 3 List of pseudoscalar mesons 4 See also 5 Footnotes 6 ReferencesHistory editThe pion p was first proposed to exist by Yukawa in the 1930s as the primary force carrying boson of the Yukawa potential in nuclear interactions 2 and was later observed at nearly the same mass that he originally predicted for it In the 1950s and 1960s the pseudoscalar mesons began to proliferate and were eventually organized into a multiplet according to Murray Gell Mann s so called Eightfold Way 3 Gell Mann further predicted the existence of a ninth resonance in the pseudoscalar multiplet which he originally called X Indeed this particle was later found and is now known as the eta prime meson h 4 The structure of the pseudoscalar meson multiplet and also the ground state baryon multiplets led Gell Mann and Zweig independently to create the well known quark model 5 6 7 The h h puzzle editDespite the pseudoscalar mesons masses being known to high precision and being the most well studied and understood mesons the decay properties of the pseudoscalar mesons particularly of eta h and eta prime h are somewhat contradictory to their mass hierarchy While the h meson is much more massive than the h meson the h meson is thought to contain a larger component of the relatively heavy strange and anti strange quarks than the h meson does which appears contradictory This failure of the quark model to explain this mass difference is called the h h puzzle The presence of an h 1405 state also brings glueball mixing into the discussion It is possible that the h and h mesons mix with the pseudoscalar glueball which should occur somewhere above the scalar glueball in mass as an unmixed state 8 This is one of a few ways in which the unexpectedly large h mass of 957 78 MeV c2 can be explained relative to its model predicted mass around 250 300 MeV c2 List of pseudoscalar mesons editMeson nonet Mesons with heavy quarks Hypothetical mesonspion 3 h meson 1 h meson 1 Kaon 4 D meson B meson h c meson h b meson h t meson b See also editList of mesons Vector meson Pseudovector meson Pseudoscalar bosonFootnotes edit Compare the definition of the pseudoscalar meson to the scalar meson Because the top quark decays into a bottom quark much faster than the cloud of gluons that bind it to other quarks can assemble a unique instance of the weak force acting more quickly than the strong force it is currently 2021 believed that composite particles containing the top quark do not form with the possible exception of collisions with such high energy that they have only ever occurred in the first milliseconds of the Big Bang 9 References edit Qin Wen Zhao Qiang Zhong Xian Hui 3 May 2018 Revisiting the pseudoscalar meson and glueball mixing and key issues in the search for pseudscalar glueball state Physical Review D 97 9 096002 arXiv 1712 02550 Bibcode 2018PhRvD 97i6002Q doi 10 1103 PhysRevD 97 096002 S2CID 59272671 Yukawa H 1935 On the interaction of elementary particles PDF Proc Phys Math Soc Jpn 17 48 Gell Mann M 15 March 1961 The eightfold way A theory of strong interaction symmetry Synchrotron Laboratory Pasadena CA California Inst of Tech doi 10 2172 4008239 TID 12608 a href Template Cite journal html title Template Cite journal cite journal a Cite journal requires journal help Kupsc Andrzej 2008 What is interesting in eta and eta Meson decays AIP Conference Proceedings 950 165 179 arXiv 0709 0603 Bibcode 2007AIPC 950 165K doi 10 1063 1 2819029 S2CID 15930194 Gell Mann M 4 January 1964 A schematic model of baryons and mesons Physics Letters 8 3 214 215 Bibcode 1964PhL 8 214G doi 10 1016 S0031 9163 64 92001 3 Zweig G 17 January 1964 An SU 3 model for strong interaction symmetry and its breaking PDF Report Vol I CERN Report No 8182 TH 401 Zweig G 1964 An SU 3 model for strong interaction symmetry and its breaking PDF Report Vol II CERN Report No 8419 TH 412 Gutsche Thomas Lyubovitskij Valery E Tich Malte C 1 July 2019 h 1405 in a chiral approach based on mixing of the pseudoscalar glueball with the first radial excitations of h and h Phys Rev D 1 8 doi 10 1103 PhysRevD 80 014014 S2CID 119195561 Fabiano N 1998 Top mesons European Physical Journal C 2 2 345 350 arXiv hep ph 9704261 Bibcode 1998EPJC 2 345F doi 10 1007 s100520050144 S2CID 17321939 nbsp This particle physics related article is a stub You can help Wikipedia by expanding it vte Retrieved from https en wikipedia org w index php title Pseudoscalar meson amp oldid 1169575554, wikipedia, wiki, book, books, library,
