( ( Color confinement ) ( , ( often ( ( ( ( ( ( ( ( simply ( called confinement ) ) , ) ( is ( ( the phenomenon ) ( ( that color ) ( charged ( ( particles ( -LRB- ( ( such ( as quarks ) ) -RRB- ) ) ) ( ( can not ) ( be ( isolated singularly ) ) ) ) ) ) ) ) ) , ) and ) therefore ) ( ( can not ) ( be ( directly observed ) ) ) ) . ) ) ) )
(ROOT (S (NP (NNP Color) (NNP confinement)) (, ,) (ADVP (RB often)) (VP (VP (ADVP (RB simply)) (VBD called) (NP (NN confinement))) (, ,) (VP (VBZ is) (NP (NP (DT the) (NN phenomenon)) (SBAR (WHNP (WDT that) (NN color)) (S (VP (VBD charged) (SBAR (S (NP (NP (NNS particles)) (PRN (-LRB- -LRB-) (PP (JJ such) (IN as) (NP (NNS quarks))) (-RRB- -RRB-))) (VP (MD can) (RB not) (VP (VB be) (VP (VBN isolated) (ADVP (RB singularly)))))))))))) (, ,) (CC and) (ADVP (RB therefore)) (VP (MD can) (RB not) (VP (VB be) (ADJP (RB directly) (JJ observed))))) (. .)))
Color confinement, often simply called confinement, is the phenomenon that color charged particles (such as quarks) cannot be isolated singularly, and therefore cannot be directly observed.
(ROOT (S (S (NP (NP (DT The) (NNS quarks)) (PP (IN in) (NP (DT a) (NN particle)))) (VP (VBP are) (VP (VBN confined)))) (, ,) (NP (VBG meaning) (JJ individual) (NNS quarks)) (VP (MD can) (RB not) (VP (VB be) (ADJP (RB directly) (JJ observed)))) (. .)))