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Kirillov character formula

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721: 1045: 556: 861: 1232: 376: 470: 333: 199: 1119: 509: 409: 257: 540: 846: 808: 716:{\displaystyle j^{1/2}(X)\chi _{\lambda }(\exp X)=\int _{{\mathcal {O}}_{\lambda +\rho }}e^{i\beta (X)}d\mu _{\lambda +\rho }(\beta ),\;\forall \;X\in {\mathfrak {g}}} 1040:{\displaystyle \int _{{\mathcal {O}}_{\lambda +1/2}}e^{i\beta (X)}d\mu _{\lambda +1/2}(\beta )={\frac {\sin((2\lambda +1)X)}{X/2}},\;\forall \;X\in {\mathfrak {g}},} 1248: 289: 754: 226: 429: 127: 41: 1281: 1134: 1265: 757: 102: 338: 106: 438: 301: 167: 76: 1056: 475: 72: 381: 1243: 231: 432: 98: 48: 44: 518: 543: 206: 148:
The Kirillov orbit method has led to a number of important developments in Lie theory, including the
138: 95: 817: 153: 260: 84: 779: 512: 149: 91: 52: 274: 852: 730: 211: 130: 56: 773: 414: 202: 112: 26: 1275: 268: 142: 1227:{\displaystyle \chi _{\lambda }(\exp X)={\frac {\sin((2\lambda +1)X)}{\sin X/2}}} 292: 264: 64: 17: 90:
At its simplest, it states that a character of a Lie group may be given by the
60: 129:. It does not apply to all Lie groups, but works for a number of classes of 134: 21: 811: 80: 769: 873: 623: 445: 308: 101:
on the coadjoint orbits, weighted by the square-root of the
1137: 1059: 864: 820: 782: 733: 559: 521: 478: 441: 417: 384: 371:{\displaystyle \lambda +\rho \in {\mathfrak {t}}^{*}} 341: 304: 277: 234: 214: 170: 115: 29: 1226: 1113: 1039: 840: 802: 748: 715: 534: 503: 464: 423: 403: 370: 327: 283: 251: 220: 193: 121: 35: 848:, centered at the origin in 3-dimensional space. 810:. The coadjoint orbits are the two-dimensional 1249:Localization formula for equivariant cohomology 465:{\displaystyle {\mathcal {O}}_{\lambda +\rho }} 328:{\displaystyle {\mathcal {O}}_{\lambda +\rho }} 194:{\displaystyle \lambda \in {\mathfrak {t}}^{*}} 8: 1114:{\displaystyle j(X)={\frac {\sin X/2}{X/2}}} 1020: 1016: 699: 695: 1213: 1166: 1142: 1136: 1100: 1087: 1075: 1058: 1028: 1027: 1002: 961: 939: 929: 904: 888: 878: 872: 871: 869: 863: 830: 819: 792: 781: 732: 707: 706: 671: 646: 628: 622: 621: 619: 591: 568: 564: 558: 526: 520: 495: 477: 450: 444: 443: 440: 416: 389: 383: 362: 356: 355: 340: 313: 307: 306: 303: 276: 243: 237: 236: 233: 213: 185: 179: 178: 169: 114: 28: 160:Character formula for compact Lie groups 504:{\displaystyle \dim \pi =d_{\lambda }} 404:{\displaystyle \mu _{\lambda +\rho }} 7: 776:are the positive half integers, and 79:. The method got its name after the 1282:Representation theory of Lie groups 1029: 708: 550:for compact Lie groups is given by 357: 252:{\displaystyle {\mathfrak {t}}^{*}} 238: 180: 1017: 696: 14: 1124:thus yielding the characters of 535:{\displaystyle \chi _{\lambda }} 291:be half the sum of the positive 1266:Graduate Studies in Mathematics 1268:, 64, AMS, Rhode Island, 2004. 1199: 1193: 1178: 1175: 1160: 1148: 1069: 1063: 994: 988: 973: 970: 955: 949: 917: 911: 743: 737: 689: 683: 659: 653: 609: 597: 584: 578: 1: 1262:Lectures on the Orbit Method 841:{\displaystyle \lambda +1/2} 548:Kirillov's character formula 335:the coadjoint orbit through 47:gives a heuristic method in 77:irreducible representations 1298: 207:irreducible representation 803:{\displaystyle \rho =1/2} 760:of the exponential map. 542:is the character of the 73:infinitesimal characters 855:, it may be shown that 1244:Weyl character formula 1228: 1115: 1041: 842: 804: 750: 717: 536: 505: 466: 425: 405: 372: 329: 285: 253: 222: 195: 133:Lie groups, including 123: 37: 1229: 1116: 1042: 843: 805: 751: 718: 537: 506: 467: 426: 406: 373: 330: 286: 284:{\displaystyle \rho } 254: 223: 196: 124: 49:representation theory 45:Kirillov orbit method 38: 1135: 1057: 862: 818: 780: 749:{\displaystyle j(X)} 731: 557: 519: 476: 439: 415: 382: 339: 302: 275: 232: 221:{\displaystyle \pi } 212: 168: 113: 96:Dirac delta function 27: 59:, which lie in the 1224: 1111: 1037: 838: 800: 746: 713: 532: 501: 462: 421: 401: 368: 325: 281: 249: 218: 191: 119: 85:Alexandre Kirillov 53:Fourier transforms 51:. It connects the 33: 1260:Kirillov, A. A., 1222: 1109: 1011: 851:By the theory of 513:Liouville measure 424:{\displaystyle G} 150:Duflo isomorphism 122:{\displaystyle j} 92:Fourier transform 36:{\displaystyle G} 1289: 1233: 1231: 1230: 1225: 1223: 1221: 1217: 1202: 1167: 1147: 1146: 1120: 1118: 1117: 1112: 1110: 1108: 1104: 1095: 1091: 1076: 1046: 1044: 1043: 1038: 1033: 1032: 1012: 1010: 1006: 997: 962: 948: 947: 943: 921: 920: 899: 898: 897: 896: 892: 877: 876: 853:Bessel functions 847: 845: 844: 839: 834: 809: 807: 806: 801: 796: 768:For the case of 755: 753: 752: 747: 722: 720: 719: 714: 712: 711: 682: 681: 663: 662: 641: 640: 639: 638: 627: 626: 596: 595: 577: 576: 572: 541: 539: 538: 533: 531: 530: 510: 508: 507: 502: 500: 499: 472:with total mass 471: 469: 468: 463: 461: 460: 449: 448: 430: 428: 427: 422: 410: 408: 407: 402: 400: 399: 377: 375: 374: 369: 367: 366: 361: 360: 334: 332: 331: 326: 324: 323: 312: 311: 290: 288: 287: 282: 258: 256: 255: 250: 248: 247: 242: 241: 227: 225: 224: 219: 200: 198: 197: 192: 190: 189: 184: 183: 128: 126: 125: 120: 57:coadjoint orbits 42: 40: 39: 34: 1297: 1296: 1292: 1291: 1290: 1288: 1287: 1286: 1272: 1271: 1257: 1240: 1203: 1168: 1138: 1133: 1132: 1096: 1077: 1055: 1054: 998: 963: 925: 900: 870: 865: 860: 859: 816: 815: 778: 777: 774:highest weights 766: 729: 728: 667: 642: 620: 615: 587: 560: 555: 554: 522: 517: 516: 511:, known as the 491: 474: 473: 442: 437: 436: 413: 412: 385: 380: 379: 354: 337: 336: 305: 300: 299: 273: 272: 235: 230: 229: 210: 209: 177: 166: 165: 162: 111: 110: 107:exponential map 25: 24: 12: 11: 5: 1295: 1293: 1285: 1284: 1274: 1273: 1270: 1269: 1256: 1253: 1252: 1251: 1246: 1239: 1236: 1235: 1234: 1220: 1216: 1212: 1209: 1206: 1201: 1198: 1195: 1192: 1189: 1186: 1183: 1180: 1177: 1174: 1171: 1165: 1162: 1159: 1156: 1153: 1150: 1145: 1141: 1122: 1121: 1107: 1103: 1099: 1094: 1090: 1086: 1083: 1080: 1074: 1071: 1068: 1065: 1062: 1048: 1047: 1036: 1031: 1026: 1023: 1019: 1015: 1009: 1005: 1001: 996: 993: 990: 987: 984: 981: 978: 975: 972: 969: 966: 960: 957: 954: 951: 946: 942: 938: 935: 932: 928: 924: 919: 916: 913: 910: 907: 903: 895: 891: 887: 884: 881: 875: 868: 837: 833: 829: 826: 823: 799: 795: 791: 788: 785: 765: 764:Example: SU(2) 762: 745: 742: 739: 736: 725: 724: 710: 705: 702: 698: 694: 691: 688: 685: 680: 677: 674: 670: 666: 661: 658: 655: 652: 649: 645: 637: 634: 631: 625: 618: 614: 611: 608: 605: 602: 599: 594: 590: 586: 583: 580: 575: 571: 567: 563: 544:representation 529: 525: 498: 494: 490: 487: 484: 481: 459: 456: 453: 447: 420: 398: 395: 392: 388: 365: 359: 353: 350: 347: 344: 322: 319: 316: 310: 280: 246: 240: 217: 203:highest weight 188: 182: 176: 173: 161: 158: 143:compact groups 118: 83:mathematician 32: 13: 10: 9: 6: 4: 3: 2: 1294: 1283: 1280: 1279: 1277: 1267: 1263: 1259: 1258: 1254: 1250: 1247: 1245: 1242: 1241: 1237: 1218: 1214: 1210: 1207: 1204: 1196: 1190: 1187: 1184: 1181: 1172: 1169: 1163: 1157: 1154: 1151: 1143: 1139: 1131: 1130: 1129: 1127: 1105: 1101: 1097: 1092: 1088: 1084: 1081: 1078: 1072: 1066: 1060: 1053: 1052: 1051: 1034: 1024: 1021: 1013: 1007: 1003: 999: 991: 985: 982: 979: 976: 967: 964: 958: 952: 944: 940: 936: 933: 930: 926: 922: 914: 908: 905: 901: 893: 889: 885: 882: 879: 866: 858: 857: 856: 854: 849: 835: 831: 827: 824: 821: 813: 797: 793: 789: 786: 783: 775: 771: 763: 761: 759: 740: 734: 703: 700: 692: 686: 678: 675: 672: 668: 664: 656: 650: 647: 643: 635: 632: 629: 616: 612: 606: 603: 600: 592: 588: 581: 573: 569: 565: 561: 553: 552: 551: 549: 545: 527: 523: 514: 496: 492: 488: 485: 482: 479: 457: 454: 451: 434: 418: 396: 393: 390: 386: 363: 351: 348: 345: 342: 320: 317: 314: 298:We denote by 296: 294: 278: 270: 269:maximal torus 266: 262: 244: 215: 208: 204: 186: 174: 171: 159: 157: 155: 151: 146: 144: 140: 136: 132: 116: 109:, denoted by 108: 104: 100: 97: 93: 88: 86: 82: 78: 74: 70: 66: 62: 58: 54: 50: 46: 30: 23: 19: 1261: 1125: 1123: 1049: 850: 767: 726: 547: 297: 163: 154:wrapping map 147: 141:groups, and 89: 68: 15: 431:-invariant 265:Lie algebra 65:Lie algebra 18:mathematics 1255:References 814:of radius 271:, and let 139:semisimple 61:dual space 1208:⁡ 1185:λ 1173:⁡ 1155:⁡ 1144:λ 1140:χ 1082:⁡ 1025:∈ 1018:∀ 980:λ 968:⁡ 953:β 931:λ 927:μ 909:β 880:λ 867:∫ 822:λ 784:ρ 704:∈ 697:∀ 687:β 679:ρ 673:λ 669:μ 651:β 636:ρ 630:λ 617:∫ 604:⁡ 593:λ 589:χ 528:λ 524:χ 497:λ 486:π 483:⁡ 458:ρ 452:λ 397:ρ 391:λ 387:μ 364:∗ 352:∈ 349:ρ 343:λ 321:ρ 315:λ 279:ρ 245:∗ 216:π 187:∗ 175:∈ 172:λ 135:nilpotent 131:connected 99:supported 71:, to the 22:Lie group 1276:Category 1238:See also 758:Jacobian 228:, where 152:and the 103:Jacobian 20:, for a 812:spheres 756:is the 433:measure 378:and by 267:of the 263:of the 259:is the 201:be the 137:, some 105:of the 94:of the 81:Russian 75:of the 63:of the 772:, the 727:where 515:. If 205:of an 43:, the 1128:(2): 770:SU(2) 546:, the 293:roots 1050:and 411:the 261:dual 164:Let 1205:sin 1170:sin 1152:exp 1079:sin 965:sin 601:exp 480:dim 435:on 67:of 55:of 16:In 1278:: 1264:, 1126:SU 295:. 156:. 145:. 87:. 1219:2 1215:/ 1211:X 1200:) 1197:X 1194:) 1191:1 1188:+ 1182:2 1179:( 1176:( 1164:= 1161:) 1158:X 1149:( 1106:2 1102:/ 1098:X 1093:2 1089:/ 1085:X 1073:= 1070:) 1067:X 1064:( 1061:j 1035:, 1030:g 1022:X 1014:, 1008:2 1004:/ 1000:X 995:) 992:X 989:) 986:1 983:+ 977:2 974:( 971:( 959:= 956:) 950:( 945:2 941:/ 937:1 934:+ 923:d 918:) 915:X 912:( 906:i 902:e 894:2 890:/ 886:1 883:+ 874:O 836:2 832:/ 828:1 825:+ 798:2 794:/ 790:1 787:= 744:) 741:X 738:( 735:j 723:, 709:g 701:X 693:, 690:) 684:( 676:+ 665:d 660:) 657:X 654:( 648:i 644:e 633:+ 624:O 613:= 610:) 607:X 598:( 585:) 582:X 579:( 574:2 570:/ 566:1 562:j 493:d 489:= 455:+ 446:O 419:G 394:+ 358:t 346:+ 318:+ 309:O 239:t 181:t 117:j 69:G 31:G

Index

mathematics
Lie group
Kirillov orbit method
representation theory
Fourier transforms
coadjoint orbits
dual space
Lie algebra
infinitesimal characters
irreducible representations
Russian
Alexandre Kirillov
Fourier transform
Dirac delta function
supported
Jacobian
exponential map
connected
nilpotent
semisimple
compact groups
Duflo isomorphism
wrapping map
highest weight
irreducible representation
dual
Lie algebra
maximal torus
roots
measure

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