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Covariant classical field theory

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In weak gravitational curvature, flat spacetime often serves as a good approximation to weakly curved spacetime. For experiment, this approximation is good. The Standard Model is defined on flat spacetime, and has produced the most accurate precision tests of physics to date.
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Then the spacetime covariant derivative on tensor or spin-tensor fields is simply the partial derivative in flat coordinates. However the gauge covariant derivative may require a non-trivial connection
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Many important examples of classical field theories which are of interest in quantum field theory are given below. In particular, these are the theories which make up the
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Bocharov, A.V. "Symmetries and conservation laws for differential equations of mathematical physics", Amer. Math. Soc., Providence, RI, 1999,
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This completes the mathematical prerequisites for a large number of interesting theories, including those given in the examples section above.
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of particle physics. These examples will be used in the discussion of the general mathematical formulation of classical field theory.
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of an associated vector bundle. The collection of these, together with gauge fields, is the matter content of the theory.
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De Leon, M., Rodrigues, P.R., "Generalized Classical Mechanics and Field Theory", Elsevier Science Publishing, 1985,
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are the correct domain for such a description. The Hamiltonian variant of covariant classical field theory is the
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as well as the required structure of an orientation, needed for a notion of integration over all of the manifold
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Griffiths, P.A., "Exterior Differential Systems and the Calculus of Variations", Boston: BirkhÀuser, 1983,
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The simplifications come from the observation that flat spacetime is contractible: it is then a theorem in
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where momenta correspond to derivatives of field variables with respect to all world coordinates.
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describing the (continuous) symmetries of internal degrees of freedom. The corresponding
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In order to formulate a classical field theory, the following structures are needed:
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Saunders, D.J., "The Geometry of Jet Bundles", Cambridge University Press, 1989,
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may admit symmetries. For example, if it is equipped with a metric
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The spacetime often comes with additional structure. Examples are
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Momentum Maps and Classical Fields Part I: Covariant Field Theory
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is flat, there are simplifications which remove this subtlety.
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from above. Then for example, more concretely we may consider
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Echeverria-Enriquez, A., Munoz-Lecanda, M.C., Roman-Roy, M.,
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Geometry of Lagrangian First-order Classical Field Theories
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Gotay, M.J., Isenberg, J., Marsden, J.E., Montgomery R.,
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which is considered to be the gauge field of the theory.
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which allows us to identify associated vector bundles as
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For example, for Minkowski space, the symmetries are the
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Suppose that the matter content is given by sections of
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Under a trivialization this can be written as a local
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is formulated as covariant classical field theory on
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This is sometimes written as 167:: coupling of scalar and spinor fields. 1788: 977:{\displaystyle E\xrightarrow {\pi } M} 664:{\displaystyle P\xrightarrow {\pi } M} 177:: coupling of scalar and gauge fields. 101: 539:Lie group–Lie algebra correspondence 1348:{\displaystyle V\otimes T_{p}^{*}M} 984:associated to the principal bundle 920:in physics. When the base manifold 875: 809: 694:is the canonical projection map on 550: 158: 13: 1294:to be a bundle where the fibre at 785: 756: 299:Metric up to conformal equivalence 239:for a more geometrical viewpoint. 54:covariant Hamiltonian field theory 44:. Nowadays, it is well known that 14: 1827: 1599:is the trivial connection on the 495:{\displaystyle {\text{Iso}}(1,3)} 192:Requisite mathematical structures 1762:Giachetta, G., Mangiarotti, L., 1425:that any fibre bundle over flat 359: 262: 22:covariant classical field theory 1187:, the Lagrangian is a function 883:{\displaystyle {\mathfrak {g}}} 817:{\displaystyle {\mathfrak {g}}} 558:{\displaystyle {\mathfrak {g}}} 452:{\displaystyle {\text{Aut}}(M)} 421:{\displaystyle {\text{Aut}}(M)} 227:This is variously known as the 1588:{\displaystyle M\rightarrow V} 1579: 1208: 1054: 1036: 853: 847: 793:{\displaystyle {\mathcal {A}}} 489: 477: 446: 440: 415: 409: 397:. The symmetries form a group 373:, these are the isometries of 1: 1688: 1121: 565:. This is referred to as the 1638:Accuracy as a physical model 738:Connections and gauge fields 366:{\displaystyle \mathbf {g} } 269:{\displaystyle \mathbf {g} } 199: 79:{\displaystyle \mathbb {R} } 7: 1646: 1562:{\displaystyle E=M\times V} 1060:{\displaystyle (V,G,\rho )} 859:{\displaystyle A_{\mu }(x)} 89: 10: 1832: 1530:{\displaystyle A_{0,\mu }} 1386:Theories on flat spacetime 909:{\displaystyle U\subset M} 1495:{\displaystyle A_{\mu }.} 1004:through a representation 1678:Non-autonomous mechanics 1627:{\displaystyle A_{\mu }} 950:associated vector bundle 58:Non-autonomous mechanics 1683:Higgs field (classical) 1390:When the base manifold 1149:: given a fiber bundle 762:{\displaystyle \nabla } 615:, otherwise known as a 327:Symmetries of spacetime 243:Structures on spacetime 181:Quantum electrodynamics 1801:Differential equations 1653:Classical field theory 1628: 1597:Levi-Civita connection 1589: 1563: 1531: 1496: 1466: 1439: 1404: 1369: 1349: 1308: 1288: 1263: 1243: 1220: 1181: 1143: 1101: 1081: 1061: 1021: 1020:{\displaystyle \rho .} 998: 978: 934: 910: 884: 860: 818: 794: 763: 734:is the base manifold. 728: 708: 688: 665: 629: 609: 589: 559: 527: 496: 453: 422: 387: 367: 345: 317: 290: 270: 218: 171:Scalar electrodynamics 80: 1796:Differential topology 1668:Variational bicomplex 1629: 1590: 1564: 1532: 1497: 1467: 1450:global trivialization 1440: 1405: 1370: 1350: 1309: 1289: 1264: 1244: 1221: 1182: 1144: 1114:or matter field is a 1102: 1082: 1062: 1022: 999: 979: 935: 911: 885: 861: 819: 795: 764: 729: 709: 689: 666: 630: 610: 590: 560: 528: 497: 454: 423: 395:Killing vector fields 388: 368: 346: 318: 291: 271: 219: 81: 50:variational bicomplex 1816:Lagrangian mechanics 1673:Quantum field theory 1611: 1573: 1541: 1508: 1476: 1456: 1429: 1394: 1359: 1318: 1298: 1273: 1253: 1233: 1191: 1153: 1133: 1091: 1071: 1033: 1008: 988: 955: 924: 894: 870: 834: 804: 780: 774:principal connection 753: 748:covariant derivative 744:principal connection 718: 698: 687:{\displaystyle \pi } 678: 642: 619: 599: 579: 545: 517: 469: 432: 401: 377: 355: 335: 307: 280: 258: 208: 68: 18:mathematical physics 1811:Theoretical physics 1410:is flat, that is, ( 1355:. This then allows 1341: 1172: 969: 656: 393:, generated by the 251:Metric: a (pseudo-) 113:Klein−Gordon theory 108:Scalar field theory 64:over the time axis 1624: 1585: 1559: 1527: 1492: 1462: 1435: 1423:algebraic topology 1400: 1375:to be viewed as a 1365: 1345: 1327: 1304: 1287:{\displaystyle E'} 1284: 1259: 1239: 1216: 1177: 1139: 1097: 1077: 1057: 1017: 994: 974: 930: 906: 880: 856: 814: 790: 759: 724: 704: 684: 661: 625: 605: 585: 555: 523: 492: 449: 418: 383: 363: 341: 313: 286: 266: 214: 204:A smooth manifold 102:Uncoupled theories 76: 38:finite-dimensional 1772:978-981-283-895-7 1764:Sardanashvily, G. 1663:Lagrangian system 1465:{\displaystyle P} 1438:{\displaystyle M} 1403:{\displaystyle M} 1368:{\displaystyle L} 1307:{\displaystyle p} 1262:{\displaystyle V} 1242:{\displaystyle E} 1173: 1142:{\displaystyle L} 1100:{\displaystyle V} 1080:{\displaystyle E} 997:{\displaystyle P} 970: 933:{\displaystyle M} 727:{\displaystyle M} 707:{\displaystyle P} 657: 628:{\displaystyle G} 608:{\displaystyle P} 588:{\displaystyle G} 526:{\displaystyle G} 475: 438: 407: 386:{\displaystyle M} 344:{\displaystyle M} 316:{\displaystyle M} 289:{\displaystyle M} 253:Riemannian metric 217:{\displaystyle M} 150:Yang–Mills theory 1823: 1738:, November 2003 1658:Exterior algebra 1633: 1631: 1630: 1625: 1623: 1622: 1594: 1592: 1591: 1586: 1568: 1566: 1565: 1560: 1536: 1534: 1533: 1528: 1526: 1525: 1501: 1499: 1498: 1493: 1488: 1487: 1471: 1469: 1468: 1463: 1444: 1442: 1441: 1436: 1409: 1407: 1406: 1401: 1374: 1372: 1371: 1366: 1354: 1352: 1351: 1346: 1340: 1335: 1313: 1311: 1310: 1305: 1293: 1291: 1290: 1285: 1283: 1268: 1266: 1265: 1260: 1248: 1246: 1245: 1240: 1225: 1223: 1222: 1217: 1215: 1207: 1186: 1184: 1183: 1178: 1164: 1163: 1148: 1146: 1145: 1140: 1106: 1104: 1103: 1098: 1086: 1084: 1083: 1078: 1066: 1064: 1063: 1058: 1026: 1024: 1023: 1018: 1003: 1001: 1000: 995: 983: 981: 980: 975: 961: 939: 937: 936: 931: 915: 913: 912: 907: 889: 887: 886: 881: 879: 878: 865: 863: 862: 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1809: 1807: 1806:Fiber bundles 1804: 1802: 1799: 1797: 1794: 1793: 1791: 1781: 1777: 1773: 1769: 1765: 1761: 1759: 1758:dg-ga/9505004 1755: 1751: 1747: 1745: 1741: 1737: 1733: 1731: 1730:3-7643-3103-8 1727: 1723: 1721: 1720:0-444-87753-3 1717: 1713: 1711: 1710:0-8218-0958-X 1707: 1703: 1701: 1700:0-521-36948-7 1697: 1693: 1692: 1684: 1681: 1679: 1676: 1674: 1671: 1669: 1666: 1664: 1661: 1659: 1656: 1654: 1651: 1650: 1644: 1635: 1619: 1615: 1604: 1602: 1598: 1582: 1576: 1556: 1553: 1550: 1547: 1544: 1522: 1519: 1516: 1512: 1502: 1489: 1484: 1480: 1459: 1451: 1446: 1432: 1424: 1419: 1417: 1413: 1397: 1383: 1380: 1378: 1362: 1342: 1337: 1332: 1328: 1324: 1321: 1301: 1280: 1277: 1256: 1236: 1227: 1204: 1201: 1197: 1194: 1174: 1169: 1165: 1160: 1157: 1136: 1129: 1119: 1117: 1113: 1108: 1094: 1074: 1051: 1048: 1045: 1042: 1039: 1027: 1014: 1011: 991: 971: 966: 962: 958: 951: 941: 927: 919: 903: 900: 897: 850: 842: 838: 830: 825: 775: 770: 749: 745: 735: 721: 701: 681: 658: 653: 649: 645: 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1580:→ 1554:× 1523:μ 1485:μ 1338:∗ 1325:⊗ 1209:→ 1170:π 1052:ρ 1012:ρ 967:π 901:⊂ 843:μ 757:∇ 682:π 654:π 574:principal 512:Lie group 233:spacetime 200:Spacetime 40:space of 1647:See also 1281:′ 1205:′ 1166:→ 1161:′ 963:→ 776:denoted 650:→ 595:-bundle 90:Examples 48:and the 30:sections 1116:section 1770:  1728:  1718:  1708:  1698:  1412:Pseudo 674:where 42:fields 1776:arXiv 1754:arXiv 1740:arXiv 1112:field 800:is a 1768:ISBN 1726:ISBN 1716:ISBN 1706:ISBN 1696:ISBN 866:, a 714:and 1452:of 1314:is 1087:is 948:An 474:Iso 437:Aut 406:Aut 276:on 32:of 28:by 16:In 1792:: 1603:. 1414:-) 1226:. 1126:A 1110:A 1107:. 772:A 572:A 569:. 510:A 502:. 459:. 323:. 224:. 86:. 20:, 1782:) 1778:: 1774:( 1756:: 1742:: 1616:A 1583:V 1577:M 1557:V 1551:M 1548:= 1545:E 1520:, 1517:0 1513:A 1490:. 1481:A 1460:P 1433:M 1398:M 1363:L 1343:M 1333:p 1329:T 1322:V 1302:p 1278:E 1257:V 1237:E 1213:R 1202:E 1198:: 1195:L 1175:M 1158:E 1137:L 1095:V 1075:E 1055:) 1049:, 1046:G 1043:, 1040:V 1037:( 1015:. 992:P 972:M 959:E 928:M 904:M 898:U 876:g 854:) 851:x 848:( 839:A 810:g 786:A 722:M 702:P 659:M 646:P 623:G 603:P 583:G 551:g 521:G 490:) 487:3 484:, 481:1 478:( 447:) 444:M 441:( 416:) 413:M 410:( 381:M 360:g 339:M 311:M 296:. 284:M 263:g 212:M 183:/ 173:/ 73:R

Index

mathematical physics
classical fields
sections
fiber bundles
finite-dimensional
fields
jet bundles
variational bicomplex
covariant Hamiltonian field theory
Non-autonomous mechanics
fiber bundles
Standard model
Scalar field theory
Klein−Gordon theory
Dirac theory
Weyl theory
Majorana theory
Gauge theories
Maxwell theory
Yang–Mills theory
Yukawa coupling
Scalar electrodynamics
chromodynamics
Quantum electrodynamics
chromodynamics
world manifold
spacetime
base manifold
Riemannian metric
Killing vector fields

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