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color: #000000;">e</span>/3 ili ±2<span style="font-style: italic; color: #000000;">e</span>/3, podložna <a href="https://www.enciklopedija.hr/clanak/jako-medjudjelovanje">jakom međudjelovanju</a>. Sve do otkrića Ω<sup>–</sup> čestice kvarkovima se pridjeljivalo čisto matematičko značenje. Prve naznake njihove fizikalne realnosti pojavile su se u pokusima duboko neelastičnoga raspršenja elektrona na protonima, na Stanfordskome linearnom akceleratoru čestica 1962. Opažanje raspršenja pod velikim kutovima (kakva su prije opažena u Rutherfordovim pokusima raspršenja α-čestica na listićima zlata) upućivalo je na postojanje tvrdih točkastih »jezgri« unutar protona. Slični pokusi provedeni potom neutrinskim snopovima na <a href="https://www.enciklopedija.hr/clanak/cern">CERN-u</a> nedvojbeno su potvrdili da je riječ o objektima trećinskog električnog naboja i polucijeloga spina. Za istraživanja putem duboko neelastičnih raspršenja kojima su ustanovljeni kvarkovi dodijeljena je <a href="https://www.enciklopedija.hr/clanak/nobelova-nagrada">Nobelova nagrada</a> za fiziku 1990 <a href="https://www.enciklopedija.hr/clanak/friedman-jerome-isaac">Jeromeu Isaacu Friedmanu</a>, <a href="https://www.enciklopedija.hr/clanak/kendall-henry-way">Henryju Wayju Kendallu</a> i <a href="https://www.enciklopedija.hr/clanak/taylor-richard-edward">Richardu Edwardu Tayloru</a>.</p><p>Godine 1974. otkriven je c-kvark (<a href="https://www.enciklopedija.hr/clanak/nobelova-nagrada">Nobelova nagrada</a> 1976. <a href="https://www.enciklopedija.hr/clanak/richter-burton">Burtonu Richteru</a> i <a href="https://www.enciklopedija.hr/clanak/ting-samuel-chao-chung">Samuelu Chaou Chungu Tingu</a> za otkriće <a href="https://www.enciklopedija.hr/clanak/j-mezon">J/Ψ-mezona</a>). Slijedilo je i otkriće b-kvarka (1977) i t-kvarka (1994). Time je bio zaokružen skup kvarkova koji s <a href="https://www.enciklopedija.hr/clanak/36121">leptonima</a> čine temeljne građevne blokove opažene tvari (→ <span style="color: #000000"><span style="font-variant:small-caps"><a href="https://www.enciklopedija.hr/clanak/fizika-elementarnih-cestica">fizika elementarnih čestica</a></span></span>). Riječ je o česticama <a href="https://www.enciklopedija.hr/clanak/spin">spina</a> 1/2, koje se pojavljuju u različitim vrstama, okusima, svrstanima u obitelji ili naraštaje. Tvari koje nas okružuju građene su od gornjega i donjega kvarka (u i d, od engl. <span style="font-style: italic; color: #000000;">up</span> i <span style="font-style: italic; color: #000000;">down</span>) prvog naraštaja. Takav uzorak s donjim kvarkom električnoga naboja (–1/3)<span style="color: #000000"><i>e</i></span> i gornjim kvarkom naboja (+2/3)<span style="color: #000000"><i>e</i></span> ponavlja se u drugome naraštaju s kvarkovima stranog i čarobnog okusa (s i c, od engl. <span style="color: #000000"><i>strange</i></span> i <span style="color: #000000"><i>charm</i></span>) te kvarkom ljepote i istine (b i t, od engl. <span style="color: #000000"><i>beauty</i></span> i <span style="color: #000000"><i>truth</i></span>) trećega naraštaja. Svaki se od navedenih kvarkova pojavljuje u tri boje. Te se boje shvaćaju kao naboji na koje se vežu <a href="https://www.enciklopedija.hr/clanak/gluon">gluoni</a>, prijenosnici <a href="https://www.enciklopedija.hr/clanak/jako-medjudjelovanje">jakoga međudjelovanja</a> opisanoga <a href="https://www.enciklopedija.hr/clanak/kvantna-kromodinamika">kvantnom kromodinamikom</a>.</p><p>Na maloj međusobnoj udaljenosti (manjoj od 10<sup>–15</sup> m) kvarkovi se gibaju kao slobodne čestice, a na većim udaljenostima djeluju iznimno velikim privlačnim silama te se zbog toga ne mogu izdvojiti iz hadrona kao zasebne čestice (→ <span style="font-variant: small-caps; color: #000000;"><a href="https://www.enciklopedija.hr/clanak/asimptotska-sloboda">asimptotska sloboda</a></span>).</p><p><span style="color:#000080"><b>Podjela kvarkova</b></span></p> <div class="table-responsive"> <table class="table table-striped"> <thead> <tr> <th>kvarkovska vrsta (okus)</th> <th>oznaka</th> <th>električni naboj <span style="font-weight:normal"><var>Q</var></span>/<var><span style="font-weight:normal">e</span></var></th> <th>masa <span style="font-weight:normal"><var>m</var></span> <span style="font-weight:normal">(MeV/</span><span style="font-weight:normal"><var>c</var></span><sup><span style="font-weight:normal">2</span></sup><span style="font-weight:normal">)</span></th> </tr> </thead> <tbody> <tr> <td>donji (down)</td> <td>d</td> <td>–1/3</td> <td>~ 4,1–5,7 </td> </tr> <tr> <td>gornji (up)</td> <td>u</td> <td>+2/3</td> <td>~ 1,7–3,1 </td> </tr> <tr> <td>strani (strange)</td> <td>s</td> <td>–1/3</td> <td>~ 100 </td> </tr> <tr> <td>čarobni (charm)</td> <td>c</td> <td>+2/3</td> <td>~ 1300 </td> </tr> <tr> <td>ljepote (beauty / bottom)</td> <td>b</td> <td>–1/3</td> <td>~ 4190 </td> </tr> <tr> <td>istine (truth / top)</td> <td>t</td> <td>+2/3</td> <td>~ 173 000</td> </tr> </tbody> </table> </div> </div> </div> </div> <div class="container citiranje"> Citiranje: <p> kvark. <i>Hrvatska enciklopedija</i>, <i>mrežno izdanje.</i> Leksikografski zavod Miroslav Krleža, 2013. – 2024. 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