In particle physics, the parton model is a model of hadrons, such as protons and neutrons, proposed by Richard Feynman. It is useful for interpreting the cascades of radiation (a parton shower) produced from quantum chromodynamics (QCD) processes and interactions in high-energy particle collisions.
The parton model was proposed by Richard Feynman in 1969, used originally for analysis of high-energy hadron collisions.[1] It was applied to electron-proton deep inelastic scattering by James Bjorken and Emmanuel Anthony Paschos.[2] Later, with the experimental observation of Bjorken scaling, the validation of the quark model, and the confirmation of asymptotic freedom in quantum chromodynamics, partons were matched to quarks and gluons. The parton model remains a justifiable approximation at high energies, and others[who?] have extended the theory[how?] over the years.
Murray Gell-Mann preferred to use the term "put-ons" to refer to partons.[3]
In 1994, partons were used by Leonard Susskind to model holography.[4]
Any hadron (for example, a proton) can be considered as a composition of a number of point-like constituents, termed "partons".
Just as accelerated electric charges emit QED radiation (photons), the accelerated coloured partons will emit QCD radiation in the form of gluons. Unlike the uncharged photons, the gluons themselves carry colour charges and can therefore emit further radiation, leading to parton showers.[5][6][7]
The hadron is defined in a reference frame where it has infinite momentum – a valid approximation at high energies. Thus, parton motion is slowed by time dilation, and the hadron charge distribution is Lorentz-contracted, so incoming particles will be scattered "instantaneously and incoherently".[citation needed]
Partons are defined with respect to a physical scale (as probed by the inverse of the momentum transfer).[clarification needed] For instance, a quark parton at one length scale can turn out to be a superposition of a quark parton state with a quark parton and a gluon parton state together with other states with more partons at a smaller length scale. Similarly, a gluon parton at one scale can resolve into a superposition of a gluon parton state, a gluon parton and quark-antiquark partons state and other multiparton states. Because of this, the number of partons in a hadron actually goes up with momentum transfer.[8] At low energies (i.e. large length scales), a baryon contains three valence partons (quarks) and a meson contains two valence partons (a quark and an antiquark parton). At higher energies, however, observations show sea partons (nonvalence partons) in addition to valence partons.[9]
A parton distribution function (PDF) within so called collinear factorization is defined as the probability density for finding a particle with a certain longitudinal momentum fraction x at resolution scale Q2. Because of the inherent non-perturbative nature of partons which cannot be observed as free particles, parton densities cannot be calculated using perturbative QCD. Within QCD one can, however, study variation of parton density with resolution scale provided by external probe. Such a scale is for instance provided by a virtual photon with virtuality Q2 or by a jet. The scale can be calculated from the energy and the momentum of the virtual photon or jet; the larger the momentum and energy, the smaller the resolution scale—this is a consequence of Heisenberg's uncertainty principle. The variation of parton density with resolution scale has been found to agree well with experiment;[10] this is an important test of QCD.
Parton distribution functions are obtained by fitting observables to experimental data; they cannot be calculated using perturbative QCD. Recently, it has been found that they can be calculated directly in lattice QCD using large-momentum effective field theory.[11][12]
Experimentally determined parton distribution functions are available from various groups worldwide. The major unpolarized data sets are:
The LHAPDF [13] library provides a unified and easy-to-use Fortran/C++ interface to all major PDF sets.
Generalized parton distributions (GPDs) are a more recent approach to better understand hadron structure by representing the parton distributions as functions of more variables, such as the transverse momentum and spin of the parton.[14] They can be used to study the spin structure of the proton, in particular, the Ji sum rule relates the integral of GPDs to angular momentum carried by quarks and gluons.[15] Early names included "non-forward", "non-diagonal" or "skewed" parton distributions. They are accessed through a new class of exclusive processes for which all particles are detected in the final state, such as the deeply virtual Compton scattering.[16] Ordinary parton distribution functions are recovered by setting to zero (forward limit) the extra variables in the generalized parton distributions. Other rules show that the electric form factor, the magnetic form factor, or even the form factors associated to the energy-momentum tensor are also included in the GPDs. A full 3-dimensional image of partons inside hadrons can also be obtained from GPDs.[17]
Parton showers simulations are of use in computational particle physics either in automatic calculation of particle interaction or decay or event generators, in order to calibrate and interpret (and thus understand) processes in collider experiments.[18] They are particularly important in large hadron collider (LHC) phenomenology, where they are usually explored using Monte Carlo simulation.
The scale at which partons are given to hadronization is fixed by the Shower Monte Carlo program. Common choices of Shower Monte Carlo are PYTHIA and HERWIG.[19][20]
{{cite journal}}
This article contains material from Scholarpedia.
Jazz Información personalApodo Jazz Nacimiento 27 de agosto de 1973 (50 años)Nueva Orleans (Estados Unidos) Residencia Nueva Orleans, LuisianaNacionalidad EstadounidenseCaracterísticas físicasAltura 1,63 m (5′ 4″)Peso 67 kg (147 lb)FamiliaCónyuge Rodney Mack (matrimonio.2008)Información profesionalOcupación Luchadora profesional (1998-2021) y gerente Años activa desde 1998Carrera deportivaDeporte Lucha libre profesional Perfil de jugadorEntrenador Personal de OVW[…
Soccer rivalry in Alberta, Canada Cavalry FC v FC EdmontonA fixture at ATCO FieldLocationAlberta (Calgary and Edmonton)TeamsCavalry FCFC EdmontonFirst meetingCavalry 1–0 EdmontonCanadian Premier League(May 18, 2019)Latest meetingCavalry 1–0 EdmontonCanadian Premier League(September 17, 2022)StadiumsClarke Stadium, EdmontonATCO Field, Foothills CountyTrophyWildrose CupStatisticsMeetings total17Most winsCavalry (14)Top scorerJordan Brown (4)All-time seriesCavalry: 14Draw: 3Edmonton: 0Largest v…
Ruta Estatal de Alabama 51 Alabama, Estados UnidosDatos de la rutaIdentificador 51 Tipo Ruta EstatalInauguración 1940Longitud 183,76 km (114.18 mi)AdministraciónAdministración ALDOTOrientación • Sur US 84 en New Brockton • Norte I-85/US 29/US 280 en OpelikaCruces US 231 noroeste del condado de Dale US 82 en Midway US 80 en Marvyn, ALUbicación 32°04′18″N 85°31′07″O / 32.07162, -85.518748Siguientes rutas AL…
Петі-ФаїPetit-Failly Країна Франція Регіон Гранд-Ест Департамент Мерт і Мозель Округ Валь-де-Бріє Кантон Лонгюїон Код INSEE 54420 Поштові індекси 54260 Координати 49°26′24″ пн. ш. 5°29′35″ сх. д.H G O Висота 204 - 313 м.н.р.м. Площа 8,12 км² Населення 87 (01-2020[1]) Густота 10,34 о
У Вікіпедії є статті про інші значення цього терміна: Кабул. Юнес Кабул Юнес Кабул Особисті дані Народження 4 січня 1986(1986-01-04) (37 років) Сен-Жульєн-ан-Женевуа, Франція Зріст 190 см Вага 87 кг Громадянство Франція Позиція захисник Професіональні клуби* Роки Клуб І (г) 2004–…
Церква святого Петра у Капернаумі 32°52′50″ пн. ш. 35°34′31″ сх. д. / 32.8805600000277778° пн. ш. 35.57537000002777461° сх. д. / 32.8805600000277778; 35.57537000002777461Координати: 32°52′50″ пн. ш. 35°34′31″ сх. д. / 32.8805600000277778° пн. ш. 35.57537000002777461° сх. д. / 32.88056…
Military high school Novosibirsk Higher Military Command SchoolНовосибирское высшее военноекомандное училищеTypeHigher military schoolEstablished1967RectorColonel Sergei MarkovchinAddress630117, Ivanov Street, 49, Novosibirsk, CampusUrbanWebsitehttps://nvvku.mil.ru/ The Novosibirsk Higher Military Command School (Russian: Новосибирское высшее военное командное училище) is Russian higher military school conducting…
National day celebrated on 2 December 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: National Day United Arab Emirates – news · newspapers · books · scholar · JSTOR (October 2018) (Learn how and when to remove this template message) National Day of the United Arab EmiratesObserved byUnited Arab Emira…
هذه المقالة يتيمة إذ تصل إليها مقالات أخرى قليلة جدًا. فضلًا، ساعد بإضافة وصلة إليها في مقالات متعلقة بها. (أبريل 2019) توماس ر. مارتن معلومات شخصية الميلاد سنة 1947 (العمر 75–76 سنة) مواطنة الولايات المتحدة الحياة العملية المدرسة الأم جامعة هارفاردجامعة برنستون المهنة…
Campeonato Brasileiro de 2016 - Série B Brasileirão 2016 - Série B Campeonato Brasileiro de Futebol de 2016 - Série B Dados Participantes 20 Organização CBF Período 14 de maio – 26 de novembro[1] Gol(o)s 894 Partidas 380 Média 2,35 gol(o)s por partida Campeão Atlético Goianiense (1º título) Vice-campeão Avaí Promovido(s) Atlético GoianienseAvaíVasco da GamaBahia Rebaixado(s) JoinvilleTupiBragantinoSampaio Corrêa Melhor marcador Bill (Ceará) – 15 gols Melhor ataque Atlético…
Brigitte BardotBardot pada tahun 1962LahirBrigitte Anne-Marie Bardot[1][2]Suami/istriRoger Vadim (1952-1957)Jacques Charrier (1959-1962)Gunter Sachs (1966-1969)Bernard d'Ormale (1992-present)AnakNicholas Charrier (b. 1960). Brigitte Bardot (Prancis IPA: [bʁiʒit baʁˈdo]) (lahir 28 September 1934) adalah pemeran wanita, model, penyanyi, aktivis hak binatang Prancis. Pada tahun 2007, ia masuk ke dalam daftar 100 Bintang Film Terseksi versi majalah Empire[3] Pada tah…
تحتاج النصوص المترجمة في هذه المقالة إلى مراجعة لضمان معلوماتها وإسنادها وأسلوبها ومصطلحاتها ووضوحها للقارئ، لأنها تشمل ترجمة اقتراضية أو غير سليمة. فضلاً ساهم في تطوير هذه المقالة بمراجعة النصوص وإعادة صياغتها بما يتناسب مع دليل الأسلوب في ويكيبيديا. (ديسمبر 2015) اضغط هنا
Final Piala Liga Inggris 1970TurnamenPiala Liga Inggris 1969–1970 Manchester City West Bromwich Albion 2 1 setelah perpanjangan waktuTanggal7 Maret 1970StadionStadion Wembley, LondonWasitV. James (York)Penonton97.963← 1969 1971 → Final Piala Liga Inggris 1970 adalah pertandingan final ke-10 dari turnamen sepak bola Piala Liga Inggris untuk menentukan juara musim 1969–1970. Pertandingan ini diselenggarakan pada 7 Maret 1970 di Stadion Wembley. Manchester City memenangkan pertandin…
Wilhelm Scholz, 1867. Grafik von Adolf Neumann Ernst Wilhelm Gotthilf[1] Scholz (* 23. Januar 1824 in Berlin; † 20. Juni 1893 Kolonie Grunewald) war ein deutscher Zeichner und Karikaturist. Inhaltsverzeichnis 1 Leben 2 Karikaturen (Auswahl) 3 Veröffentlichungen (Auswahl) 4 Literatur 5 Weblinks 6 Einzelnachweise Leben Sein Vater war Geheimer Archivrat in Berlin. Scholz besuchte das Gymnasium zum Grauen Kloster und wurde an der Kunstakademie bei Karl Wilhelm Wach ausgebildet. Seine Absi…
Esta página cita fontes, mas que não cobrem todo o conteúdo. Ajude a inserir referências. Conteúdo não verificável pode ser removido.—Encontre fontes: ABW • CAPES • Google (N • L • A) (Maio de 2019) Coordenadas: 20° 09' S 47° 16' 51 O Usina Hidrelétrica de Estreito (Luís Carlos B. Carvalho) Localização Localização Rio Grande, São Paulo, Brasil Bacia hidrográfica Bacia do rio da Prata Coordenadas 20°9&…
Bodybuilding in IndiaCountryIndiaGoverning bodyIndian Body Building Federation (IBBF)National team(s)India Bodybuilding in India is organized and the national federation is internationally recognised. Bodybuilders from the country have competed in international events. History In 2013, the Kazakhstani Bodybuilding and Fitness Federation hosted the Asian Championship in Almaty at the Baluan Sholak Sport Palace. At least one Indian participated in the competition.[1] Culture In India, body…
Species of butterfly Delias echidna In Hewitson's Illustrations of New Species of Exotic Butterflies Scientific classification Domain: Eukaryota Kingdom: Animalia Phylum: Arthropoda Class: Insecta Order: Lepidoptera Family: Pieridae Genus: Delias Species: D. echidna Binomial name Delias echidna(Hewitson, 1861)[1] Synonyms Pieris echidna Hewitson, 1861 Delias echidna is a butterfly in the family Pieridae. It was described by William Chapman Hewitson in 1861. It is found in the Indoma…
У этого топонима есть и другие значения, см. Исполкомская улица. Исполкомская улица Общая информация Страна Россия Город Санкт-Петербург Район Центральный Исторический район Пески Протяжённость 580 м Метро Пл. Александра Невского-1, Пл. Александра Невского-2 Прежние н…
Japanese Bangladeshisজাপানী বাংলাদেশীTotal population24,940 (in June, 2023)[1][2]Regions with significant populationsTokyo (mainly Shinjuku and Shibuya), Anjō, Chiba, Handa, Kariya, Kawasaki, Kōbe, Komaki, Kyoto, Nagoya, Ōsaka, Saitama, Sakai, Tōkai, Yokohama[citation needed]LanguagesEnglish · Bengali · JapaneseReligionIslam, Hinduism, Buddhism, Christianity, ShintoismRelated ethnic groupsBangladeshi diaspora B…
1948 novel The Paper Bag First edition (UK)AuthorJohn RhodeCountryUnited KingdomLanguageEnglishSeriesLancelot PriestleyGenreDetectivePublisherGeoffrey Bles (UK) Dodd Mead (US)Publication date1948Media typePrintPreceded byDeath of an Author Followed byThe Telephone Call The Paper Bag is a 1948 detective novel by John Rhode, the pen name of the British writer Cecil Street.[1][2] It is the forty sixth in his long-running series of novels featuring Lancelot …
Lokasi Pengunjung: 3.144.230.33