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Lectures on the functional renormalization group method

  • Review Article
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Central European Journal of Physics

Abstract

These introductory notes are about functional renormalization group equations and some of their applications. It is emphasised that the applicability of this method extends well beyond critical systems, it actually provides us a general purpose algorithm to solve strongly coupled quantum field theories. The renormalization group equation of F. Wegner and A. Houghton is shown to resum the loop-expansion. Another version, due to J. Polchinski, is obtained by the method of collective coordinates and can be used for the resummation of the perturbation series. The genuinely non-perturbative evolution equation is obtained by a manner reminiscent of the Schwinger-Dyson equations. Two variants of this scheme are presented where the scale which determines the order of the successive elimination of the modes is extracted from external and internal spaces. The renormalization of composite operators is discussed briefly as an alternative way to arrive at the renormalization group equation. The scaling laws and fixed points are considered from local and global points of view. Instability induced renormalization and new scaling laws are shown to occur in the symmetry broken phase of the scaler theory. The flattening of the effective potential of a compact variable is demonstrated in case of the sine-Gordon model. Finally, a manifestly gauge invariant evolution equation is given for QED.

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References

  1. N.N. Bogoliubov, D.V. Shirkov, Introduction to the Theory of Quantized Fields, 3rd ed., John Wiley and Sons, New York, 1973.

    Google Scholar 

  2. K.G. Wilson, J. Kogut, Phys. Rep. c 12, 77 (1974); K.G. Wilson, Rev. Mod. Phys. 47, 773 (1975); Rev. Mod. Phys. 55, 583 (1983).

    Article  ADS  Google Scholar 

  3. P.W. Anderson, G.J. Yuval, J. Phys. c 4, 607 (1971).

    Article  ADS  Google Scholar 

  4. M. Gellman, F. Low, Phys. Rev. 95 1300 (1954).

    Article  ADS  Google Scholar 

  5. N. Goldenfeld, O. Martin, V. Oono, and F. Liu, Phys. Rev. Lett. 64, 1361 (1990); T. Kunihiro, Progr. of Theor. Phys. 95, 503 (1995).

    Article  ADS  Google Scholar 

  6. C. G. Callan Phys. Rev. d 2, 1541 (1970); K. Symanzik, Comm. Math. Phys. 18, 227 (1970).

    Article  ADS  Google Scholar 

  7. J. Alexandre, V. Branchina, J. Polonyi, Phys. Rev. d 58, 16002 (1988).

    Article  Google Scholar 

  8. F.J. Wegner, A. Houghton, Phys. Rev. a 8, 401 (1973).

    Article  ADS  Google Scholar 

  9. J. Polchinski, Nucl. Phys. b 231, 269 (1984).

    Article  ADS  Google Scholar 

  10. T. Morris, Int. J. Mod. Phys. A9 (1994) 2411.

    Article  MATH  ADS  Google Scholar 

  11. J. Collins, Renormalization, Cambridge University Press, 1984.

  12. J. Polonyi, K. Sailer, Phys. Rev. d 63, 105006 (2001).

    Article  ADS  Google Scholar 

  13. J. Hughes and J. Liu, Nucl. Phys. b 307, 183 (1988); J Hughes, Nucl. Phys. b 312, 125 (1989); G.M. Shore, Nucl. Phys. b 362, 85 (1991); G. Keller and C. Kopper, Comm. Math. Phys. 148, 445 (1992); Comm. Math. Phys. 153, 245 (1993); C. Becchi, On the Construction of Renormalized Gauge Theories Using Renormalization Group Techniques, hep-th/9607188.

    Article  ADS  MathSciNet  Google Scholar 

  14. B.P. Dolan, Int. J. of Mod. Phys. 10, 2439 (1995); Int. J. of Mod. Phys. 10, 2703 (1995); Int. J. of Mod. Phys. 12, 2413 (1995); D.C. Brody, A. Ritz, Nucl. Phys. b 522, 588 (1998); B.P. Dolan, A. Lewis, Phys. Lett. b 460 302 (1999).

    Article  MATH  ADS  MathSciNet  Google Scholar 

  15. G. Altarelli, G. Parisi, Nucl. Phys. b 126, 278 (1977); A. H. Mueller, Phys. Rep. 73, 237 (1981).

    Article  Google Scholar 

  16. C. Wetterich, Phys. Lett. b 301, 90, (1993).

    Article  ADS  Google Scholar 

  17. T. Morris, Phys. Lett. b 329, 241 (1944).

    ADS  Google Scholar 

  18. D. Litim, Optimized renormalization group flow, hep-th/0103195.

  19. M. Reuter and C. Wetterich, Nucl. Phys. b 391, 147 (1993); N. Tetradis and D.F. Litim, Nucl. Phys. b 464, 492 (1996).

    Article  ADS  Google Scholar 

  20. U. Ellwanger, Phys. Lett. b 335, 364 (1994).

    Article  ADS  Google Scholar 

  21. J. Adams, J. Berges, S. Bornholdt, F. Freire, N. Tetradis, C. Wetterich, Mod. Phys. Lett. a 10, 2367 (1995).

    Article  ADS  Google Scholar 

  22. J. Alexandre, J. Polonyi, Ann. Phys. 288, 37 (2001).

    Article  MATH  ADS  Google Scholar 

  23. S. Coleman, E. Weinberg, Phys. Rev. d 7, 1888 (1973).

    Article  ADS  Google Scholar 

  24. A. Parola, L. Reatto, Phys. Rev. Lett. 53, 2417 (1984); Phys. Rev. a 31, 3309 (1985); V. I. Tikar, Phys. Lett. a 104, 135 (1984); J. Comellas, A. Travesset, Nucl. Phys. b 498, 539 (1997).

    Article  ADS  Google Scholar 

  25. K. I. Aoki et al, Progr. of Theor. Phys. 95, 409 (1996).

    Article  ADS  Google Scholar 

  26. S. B. Liao, M. Strickland, Nucl. Phys. b 497, 611 (1997).

    Article  Google Scholar 

  27. A. Margaritis, G. Ódor, A. Patkos, Z. Phys. c 39, 109 (1998)

    Article  ADS  Google Scholar 

  28. P. E. Haagensen, Y. Kubyshin, J. I. Latorre, E. Moreno, Phys. Lett. b 323, 330 (1994)

    Article  ADS  Google Scholar 

  29. T. Morris, Phys. Lett. b 334, 355 (1994).

    Article  ADS  Google Scholar 

  30. N. Tetradis, C. Wetterich, Nucl. Phys. b 422, 541 (1994).

    Article  ADS  Google Scholar 

  31. M. Alford, Phys. Lett. b 336, 237 (1994).

    Article  ADS  Google Scholar 

  32. S. Liao, J. Polonyi, M. Strickland, Nucl. Phys. b 567, 493 (2000).

    Article  MATH  ADS  MathSciNet  Google Scholar 

  33. D. F. Litim, Phys. Lett. b 486, 92 (2000); Int. J. of Mod. Phys. 16, 2081 (2001).

    Article  ADS  Google Scholar 

  34. S. Seide, C. Wetterich, Nucl. Phys. b 562, 524 (1999).

    Article  ADS  Google Scholar 

  35. J. Berges, C. Wetterich, Nucl. Phys. b 487, 675 (1997).

    Article  MATH  MathSciNet  Google Scholar 

  36. M. Maggiore, Z. Phys. c 41, 687 (1989); T. E. Clarke, B. Haeri, S. T. Love, Nucl. Phys. b 402, 628 (1993); M. D’Attanasio, T. Morris, Phys. Lett. b 409, 363 (1997); J. Berges, D. U. Jungnickel, C. Wetterich, Phys. Rev. d 59, 034010 (1999);

    Article  Google Scholar 

  37. D. Zanchi, H. J. Schultz, Phys. Rev. b 54, 9509 (1996); Phys. Rev. b 61, 13609 (2000); C. J. Halboth, W. Metzner, Phys. Rev. b 61, 4364 (2000); C. Honerkamp, M. Salmhofer, N. Furukawa, T. M. Rrice, Phys. Rev. b 63][45114, 2001 (;) M. Salmhofer. C. Honerkamp, Progr. of Theor. Phys. 105, 1 (2001); S. Correia, J. Polonyi, J. Richert, Functional Callan-Symanzik Equation for the Coulomb Gas, cond-mat/0108048.

    Article  ADS  Google Scholar 

  38. J. Polonyi, Current-density functional for disordered systems, cond-mat/0203090.

  39. A. Bonanno, M. Reuter, Phys. Rev. d 62, 043008 (2000).

    Article  ADS  Google Scholar 

  40. H. Gies, C. Wetterich, Renormalization group flow of bound states, hep-th/0107221.

  41. J. Polonyi, K. Sailer, Effective actions for the density functional theory, cond-mat/0108179.

  42. C. Bagnuls, C. Bervillier, hep-th/0002034; Berges, N. Tetradis, C. Wetterich, hep-th/0005122.

  43. Proceedings of Workshop on the Exact Renormalization Group, Faro, Portugal, 1998, ed. Krasnitz et al. (World Scientific, Singapore, 1999); 2nd Conference on Exact RG, Rome 2000, ed. S. Arnone, at al. Int. J. of Mod. Phys. 16, 1809 (2001).

    Google Scholar 

  44. C. Harvey-Fros, PhD Thesis, university of Southampton, hep-th/0108018; M. D. Turner, PhD Thesis, University of Southampton, hep-th/0108031.

  45. F. Wegner, J. Phys. c 7, 2098 (1974).

    Article  ADS  Google Scholar 

  46. J. I. Latorre, T. Morris, Int. J. of Mod. Phys. 16, 2071 (2001).

    Article  MathSciNet  Google Scholar 

  47. L. Schulmann, Techniques and Applications of Path Integrations, John Wiley and Sons, New York, 1981.

    Google Scholar 

  48. D. McLaughlin, L. Schulman, J. Math. Phys. 12, 2520 (1971).

    Article  ADS  MathSciNet  Google Scholar 

  49. J. Polonyi, Ann. Phys. 252, 300 (1996).

    Article  MATH  ADS  MathSciNet  Google Scholar 

  50. R. D. Ball, P. E. Haagensen, J. I. Latorre, E. Moreno, Phys. Lett. b 347, 80 (1995);

    Article  ADS  MathSciNet  Google Scholar 

  51. J. Comellas, Phys. Lett. b 509, 662 (1998).

    MATH  MathSciNet  Google Scholar 

  52. T. Morris, Nucl. Phys. b 495, 477 (1997); Phys. Rev. Lett. 77, 1658 (1996).

    Article  Google Scholar 

  53. A. Hasenfratz, P. Hasenfratz, Nucl. Phys. b 270, 687 (1986).

    Article  ADS  Google Scholar 

  54. K. Halpern, K. Huang, Phys. Rev. d 35, 3252 (1996); Phys. Rev. Lett. 77, 1659 (1996); V. Periwal, Mod. Phys. Lett. a 11, 2915 (1996); K. Halpern, Phys. Rev. d 57, 6337 (1998).

    Article  ADS  Google Scholar 

  55. G. Felder, Comm. Math. Phys. 111, 101 (1987); A. E. Filippov, S. A. Breus, Phys. Lett. a 158, 300 (1981); S. A. Breus, A. E. Filippov, Physica a 192, 486 (1993); T. Morris, Phys. Rev. Lett. 1658, 1996 (.)

    Article  MATH  ADS  MathSciNet  Google Scholar 

  56. T. Morris, Phys. Lett. b 329, 241 (1994).

    Article  ADS  MathSciNet  Google Scholar 

  57. C. Bagnulus, C. Bervillier, Phys. Rev. b 41, 402 (1990).

    Article  ADS  Google Scholar 

  58. T. Morris, Phys. Lett. b 345, 139 (1995);

    Article  ADS  Google Scholar 

  59. R. Jackiw, S. Templeton, Phys. Rev. d 23, 2291 (1981).

    Article  ADS  Google Scholar 

  60. J. Polchinski, in Proceedings of the 1992 TASI Elementary Particle Physics, Eds. J. Polchinski and J. Harvey, World Sci., 1992.

  61. S. Weinberg, Nucl. Phys. b 413, 567 (1994).

    Article  ADS  Google Scholar 

  62. R. Shankar, Rev. Mod. Phys. 66, 129 (1994).

    Article  ADS  MathSciNet  Google Scholar 

  63. J. Polonyi, Nucl. Phys. (Proc. Suppl.)B20 (1991) 32; Confinement and Renormalization, hep-ph/9511243, in the Proceedings of the International School of Physics, Enrico Fermi, Course CXXX, on Selected Topics in Nonperturbative QCD, Soc. It. di Fisica; K. Johnson, L. Lellouch, J. Polonyi, Nucl. Phys. b 367, 675 (1991).

    Article  MATH  ADS  MathSciNet  Google Scholar 

  64. V. A. Miransky, Nuovo Cimento a 90, 149 (1985); P.I. Fomin, V. P. Gusynin, V. A. Miransky, Yu. A. Sitenko, Riv. Nuovo Cimento 6, 1 (1983); C. N. Leung, S. T. Love, W. A. Bardeen, Nucl. Phys. b 273, 649 (1986); W. A. Bardeen, S. T. Love, C. N. Leung, Nucl. Phys. b 323, 493 (1989).

    Article  ADS  Google Scholar 

  65. T. Appelquist, T. Takeuchi, M. B. Einhorn, L. C. R. Wijewardhana, Phys. Lett. b 220, 223 (1989); K. Matumoto, Progr. of Theor. Phys. 81, 277 (1989); T. Takeuchi, Phys. Rev. d 40, 2697 (1989).

    Article  ADS  Google Scholar 

  66. V. A. Miransky, M. Tanabashi, K. Yamawaki, Phys. Lett. b 221, 177 (1989); Mod. Phys. Lett. a 4, 1043 (1989).

    Article  ADS  Google Scholar 

  67. V. A. Miransky, Int. J. of Mod. Phys. 6, 1641 (1991).

    Article  ADS  MathSciNet  Google Scholar 

  68. Y. Nambu, Proceedings of the 1989 Workshop on Dynamical Symmetry Breaking, eds. T. Muta, K. Yamawaki (Nagoya University, 1990); W. J. marciano, Phys. Rev. Lett. 62, 2793 (1989); Phys. Rev. d 41, 1647 (1990); W. A. Bardeen, C. T. Hill, M. Lindner, Phys. Rev. d 41, 1647 (1990).

  69. V. A. Alessandrini, H. de Vega, F. Schaposnik, Phys. Rev. b 10, 3906 (1974); Phys. Rev. b 12, 5034 (1975); T. Appelquist, J. Carazzone, Phys. Rev. d 11, 2865 (1975); T. Appelquist, J. Carazzone, H. Kluberg-Stern, M. Roth, Phys. Rev. Lett. 36, 768 (1976), Phys. Rev. Lett. 36, 1161 (1976); T. Appelquist, J. Carazzone, Nucl. Phys. b 120, 77 (1977).

    Article  ADS  Google Scholar 

  70. J. S. Bell, R. Jackiw, Nuovo Cimento a 60, 47 (1969); S. Adler, Phys. Rev. 177, 2426 (1969).

    Article  ADS  Google Scholar 

  71. S. Adler, J. Collins, A. Duncan, Phys. Rev. d 15, 1712 (1977); J. Collins, A. Duncan, S. Joeglekar, Phys. Rev. d 16, 438 (1977); N. K. Nielsen, Nucl. Phys. b 120, 212 (1977).

    Article  Google Scholar 

  72. V. Branchina, J. Polonyi, Nucl. Phys. b 433, 99 (1995).

    Article  ADS  Google Scholar 

  73. M. E. Fischer, in Proceedings of the Conference Renormalization Group in Critical Phenomena and Quantum Field Theory, edt. J. D. Gunton, M. S. Green, Temple University, 1973.

  74. J. Alexandre, V. Branchina, J. Polonyi, Phys. Lett. b 445, 351 (1999).

    Article  ADS  Google Scholar 

  75. A. Ringwald, C. Wetterich, Nucl. Phys. b 334, 506 (1990); N. Tetradis, C. Wetterich, Nucl. Phys. b 383, 197 (1992).

    Article  ADS  Google Scholar 

  76. R. B. Griffith, P. A. Pierce, Phys. Rev. Lett. 41, 917 (1978); J. Stat. Physics. 20, 499 (1979); O. Hudák, Phys. Lett. a 73, 273 (1979); C. Rebbi, R. H. Swendsen, Phys. Rev. b 21, 4094 (1980); R. B. Griffith, Physica a 106, 59 (1981); A. Stella, Physica a 108, 211 (1981).

    Article  ADS  Google Scholar 

  77. A. Hasenfratz, P. Hasenfratz, Nucl. Phys. b 295, 1 (1988)

    Article  ADS  MathSciNet  Google Scholar 

  78. H. W. Blöte, R. H. Swendsen, Phys. Rev. Lett. 43, 799 (1979); C. Lang, Nucl. Phys. b 280, 255 (1987); K. Decker, A. Hasenfratz, P. Hasenfratz, Nucl. Phys. b 295, 21 (1988); A. Gonzales-Arroyo, M. Okawa, Y. Shimizu, Phys. Rev. Lett. 60, 487 (1988); F. Igloi, C. Vanderzande, Physica a 135, 347 (1986).

    Article  ADS  Google Scholar 

  79. R. B. Israel, in Random Fields (Esztergom, 1979), J. Fritz, J. L. Lebowitz, D. Szász eds. (North-Holland, Amsterdam, 1981); A. C. D. van Enter, R. Fernández, A. Sokal, J. Stat. Physics. 72, 879 (1993).

  80. J. Alexandre, J. Polonyi, Tree-level renormalization, hep-th/9906017.

  81. Sz. Borsanyi, A. Patkos, J. Polonyi, Zs. Szep, Phys. Rev. d 62, 085013 (2000).

    Article  ADS  Google Scholar 

  82. S. Matinyan, G. Savvidy, Nucl. Phys. b 134, 539 (1978); G. Savvidy, Phys. Lett. b 71, 133 (1977); M. Duff, R. Ramón-Medrano, Phys. Rev. d 12, 3357 (1976); H. Pagels, E. Tomboulis, Nucl. Phys. b 143, 485 (1978).

    Article  ADS  Google Scholar 

  83. N. K. Nielsen, P. Olesen, Nucl. Phys. b 144, 376 (1978); Phys. Lett. b 79, 304 (1978); J. Amjorn, N. K. Nielsen, P. Olesen, Nucl. Phys. b 152, 75 (1979); H. B. Nielsen, P. Olesen, Nucl. Phys. b 160, 380 (1979); H. B. Nielsen, M. Ninomiya, Nucl. Phys. b 156, 1 (1979); J. Amjorn, P. Olesen, Nucl. Phys. b 60, 1980 (.)

    Article  ADS  MathSciNet  Google Scholar 

  84. G. Dosch, Phys. Lett. b 190, 555 (1987); G. Dosch, Y. Simonov, Phys. Lett. b 205, 339 (1988); Y. Simonov, Yad. Fiz. 48, 1381 (1988); Yad. Fiz. 50, 213 (1988).

    Google Scholar 

  85. G. ’tHooft, Phys. Rev. Lett. 37, 8 (1976).

    Article  ADS  Google Scholar 

  86. J. Fingberg, J. Polonyi, Nucl. Phys. b 486, 315 (1997); V. Branchina and H. Mohrbach, J. Polonyi, Phys. Rev. d 60, 45006 (1999); Phys. Rev. d 60, 45007 (1999); M. Dufour Fournier, J. Polonyi, Phys. Rev. d 61, 065008 (2000).

    Article  Google Scholar 

  87. K. Huang, J. Polonyi, Int. J. of Mod. Phys. 6, 409 (1991).

    Article  ADS  MathSciNet  Google Scholar 

  88. I. Nándori, J. Polonyi, K. Sailer, Phys. Rev. d 63, 045022 (2001).

    Article  ADS  Google Scholar 

  89. J. M. Kosterlitz, D. J. Thouless, Journal J. Phys. CC61181973; J. M. Kosterlitz, Journal J. Phys. CC710461974.

  90. J. V. Jose, L. P. Kadanoff, S. Kirkpatrick, D. R. Nelson, Phys. Rev. b 16, 1217 (1977).

    Article  Google Scholar 

  91. S. Coleman, Phys. Rev. d 11, 3424 (1975).

    Article  Google Scholar 

  92. S. Mandelstam, Phys. Rev. d 11, 3026 (1975).

    Article  MathSciNet  Google Scholar 

  93. S. Samuel, Phys. Rev. d 18, 1916 (1978).

    Article  ADS  MathSciNet  Google Scholar 

  94. J. Polonyi, The confinement-deconfinement mechanism, in Quark Gluon Plasma, World Scientific, 1990, R. Hwa, edt.

  95. N. D. Mermin, H. Wagner, Phys. Rev. Lett. 17, 1133 (1966); S. Coleman, Comm. Math. Phys. 31, 259 (1973).

    Article  ADS  Google Scholar 

  96. G. V. Gersdorff, C. Wetterich, Nonperturbative Renormalization Flow and Essential Scaling for the Kosterlitz-Thouless Transition, hep-th/0008114.

  97. C. Becchi, in Elementary Particles, Field Theory and Statistical Mechanics, Eds. M. Bonini, G. Marchesini, E. Onofri, Parma University 1993, hep-th/9607188; M. Bonini, M. D’Attanasio, G. Marchesini, Nucl. Phys. b 409, 1993 (441); Nucl. Phys. b 418, 1994 (81); Nucl. Phys. b 421, 1994 (429); Nucl. Phys. b 437, 1995 (163); M. Reuter, C. Wetterich, Nucl. Phys. b 417, 181 (1994); Nucl. Phys. b 427, 291 (1994); M. D’Attanasio, T. R. Morris, Phys. Lett. b 378, 213 (1996).

  98. D. F. Litim, J. M. Pawlowski, Phys. Lett. b 435, 181 (1998); F. Freire, D. F. Litim, J. M. Pawlowski, Phys. Lett. b 495, 256 (2000).

    Article  Google Scholar 

  99. T. R. Morris, Nucl. Phys. b 573, 97 (2000), J. High of Energy Phys. 0012, 012 (2000).

    Article  MATH  ADS  Google Scholar 

  100. M. Simionato, Int. J. of Mod. Phys. 15, 2121 (2000); Int. J. of Mod. Phys. 15, 2153 (2000).

    MATH  ADS  MathSciNet  Google Scholar 

  101. J.Alexandre, J. Polonyi, K. Sailer, in preparation.

  102. K. Wilson, Rev. Mod. Phys. 55, 583 (1983).

    Article  ADS  Google Scholar 

  103. M. E. Fischer, in the Proceedings of Enrico Fermi International School of Physics, ed. M. S. Green (Academic Press, New York, 1971); M. P. Nightingale, Physica a 83, 561 (1976).

    Google Scholar 

  104. K. Wilson, M. E. Fischer, Phys. Rev. Lett. 28, 248 (1972); K. Wilson, Phys. Rev. d 7, 2911 (1973).

    ADS  Google Scholar 

  105. P. C. Hohenberg, B. I. Halperin, Rev. Mod. Phys. 49, 435 (1977).

    Article  Google Scholar 

  106. G. ’tHooft, Proceedings of Colloquim on Renormalization of Yang-Mills Fields and Application to Particle Physics, ed. C. P. Korthes-Altes, (Marseilles, 1972); D. Gross, F. Wilcek, Phys. Rev. Lett. 30, 1343 (1973); H. D. Politzer, Phys. Rev. Lett. 30, 1346 (1973); S. Coleman, D. Gross, Phys. Rev. Lett. 31, 851 (1973).

  107. S. Weinberg, Physica a 96, 327 (1979); J. Gasser, H. Leutwyler, Ann. Phys. 158, 142 (1984); Nucl. Phys. b 250, 465 (1985); Phys. Rep. 87, 77 (1982); D. B. Kaplan, A. V. Manohar, Phys. Rev. Lett. 56, 2004 (1986).

    Article  ADS  Google Scholar 

  108. S. Weinberg, Phys. Lett. b 91, 51 (1980) I. J. R. Aitchison, Acta Phys. Polonica b 18, 191 (1987).

    Article  ADS  Google Scholar 

  109. N. Isgur, M. B. Wise, Phys. Lett. b 232, 113 (1989); Phys. Lett. b 237, 527 (1990).

    Article  ADS  Google Scholar 

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Polonyi, J. Lectures on the functional renormalization group method. centr.eur.j.phys. 1, 1–71 (2003). https://doi.org/10.2478/BF02475552

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