Published Online: 26 January 2017
Accepted: January 2017
Journal of Mathematical Physics 58, 013503 (2017); https://doi.org/10.1063/1.4974449
more...View Affiliations
  • 1Department of Mathematics and Center for Mathematical Analysis, Geometry and Dynamical Systems, Instituto Superior Técnico, University of Lisbon, Lisbon, Portugal
  • 2Department of Mathematics, Faculty of Science and Technology, University of Macau, Macau, China
We study a transform, inspired by coherent state transforms, from the Hilbert space of Clifford algebra valued square integrable functions L2(ℝm, dx) ⊗ ℂm to a Hilbert space of solutions of the Weyl equation on ℝm+1 = ℝ × ℝm, namely, to the Hilbert space ℳL2(ℝm+1, ) of ℂm-valued monogenic functions on ℝm+1 which are L2 with respect to an appropriate measure . We prove that this transform is a unitary isomorphism of Hilbert spaces and that it is therefore an analog of the Segal-Bargmann transform for Clifford analysis. As a corollary, we obtain an orthonormal basis of monogenic functions on ℝm+1. We also study the case when ℝm is replaced by the m-torus 𝕋m. Quantum mechanically, this extension establishes the unitary equivalence of the Schrödinger representation on M, for M = ℝm and M = 𝕋m, with a representation on the Hilbert space ℳL2(ℝ × M, ) of solutions of the Weyl equation on the space-time ℝ × M.
The authors would like to thank Frank Sommen for useful comments. J.M. and J.P.N. thank also Pedro Girão and Jorge Silva for helpful discussions.
The authors were partially supported by Macau Government FDCT through the Project No. 099/2014/A2, Two related topics in Clifford analysis, and by the University of Macau Research Grant No. MYRG115(Y1-L4)-FST13-QT. J.M. and J.P.N. were also partly supported by FCT/Portugal through the Project Nos. UID/MAT/04459/2013, EXCL/MAT-GEO/0222/2012, and PTDC/MAT-GEO/3319/2014 and by the (European Cooperation in Science and Technology) COST Action No. MP1405 QSPACE.
  1. 1. Bargmann, V., “On a Hilbert space of analytic functions and an associated integral transform part I,” Commun. Pure Appl. Math. 14, 187–214 (1961). https://doi.org/10.1002/cpa.3160140303, Google ScholarCrossref
  2. 2. Brackx, F., Delanghe, R., and Sommen, F., Clifford Analysis, Research Notes in Mathematics Vol. 76 (Pitman, Boston, 1982). Google Scholar
  3. 3. Colombo, F., Lavicka, R., Sabadini, I., and Soucek, V., “The Radon transform between monogenic and generalized slice monogenic functions,” Math. Ann. 363, 733 (2015). https://doi.org/10.1007/s00208-015-1182-3, Google ScholarCrossref
  4. 4. Colombo, F., Sabadini, I., and Struppa, D. C., “Slice monogenic functions,” Isr. J. Math. 171, 385–403 (2009). https://doi.org/10.1007/s11856-009-0055-4, Google ScholarCrossref
  5. 5. Colombo, F., Sabadini, I., and Struppa, D. C., “An extension theorem for slice monogenic functions and some of its consequences,” Isr. J. Math. 177, 369–389 (2010). https://doi.org/10.1007/s11856-010-0051-8, Google ScholarCrossref
  6. 6. Colombo, F., Sabadini, I., and Struppa, D. C., Noncommutative Functional Calculus (Birkhäuser, 2011). Google ScholarCrossref
  7. 7. De Bie, H., Peña Peña, D., and Sommen, F., “Generating functions of orthogonal polynomials in higher dimensions,” J. Approximation Theory 178, 30–40 (2014). https://doi.org/10.1016/j.jat.2013.11.003, Google ScholarCrossref
  8. 8. Delanghe, R., Sommen, F., and Soucek, V., Clifford Algebra and Spinor–Valued Functions, Mathematics and Its Applications Vol. 53 (Kluwer, 1992). Google ScholarCrossref
  9. 9. De Schepper, N. and Sommen, F., “Cauchy–Kowalevski extensions and monogenic plane waves using spherical monogenics,” Bull. Braz. Math. Soc. New Ser. 44, 321–350 (2013). https://doi.org/10.1007/s00574-013-0016-8, Google ScholarCrossref
  10. 10. Diki, K. and Ghanmi, A., “A quaternionic analogue of the Segal-Bargmann transform,” Complex Anal. Oper. Theory (published online, 2016). https://doi.org/10.1007/s11785-016-0609-5, Google ScholarCrossref
  11. 11. Driver, B., “On the Kakutani-Itô-Segal-Gross and Segal-Bargmann-Hall isomorphisms,” J. Funct. Anal. 133, 69–128 (1995). https://doi.org/10.1006/jfan.1995.1120, Google ScholarCrossref
  12. 12. Fueter, R., “Die Funktionentheorie der Differetialgleichungen Δu = 0 und ΔΔu = 0 mit vier reellen Variablen,” Commun. Math. Helvetici 7, 307–330 (1935). https://doi.org/10.1007/BF01292723, Google ScholarCrossref
  13. 13. Hall, B. C., “The Segal-Bargmann “coherent-state” transform for Lie groups,” J. Funct. Anal. 122, 103–151 (1994). https://doi.org/10.1006/jfan.1994.1064, Google ScholarCrossref
  14. 14. Hall, B. C., Holomorphic Methods in Analysis and Mathematical Physics, First Summer School in Analysis and Mathematical Physics (Cuernavaca Morelos, 1998) [Contemp. Math. 260, 1–59 (2000)]. Google Scholar
  15. 15. Hall, B. C., “The range of the heat operator,” in Contemporary Mathematics, The Ubiquitous Heat Kernel, AMS Special Session, Providence, RI, October 24, 2003, edited by J. Jayet al. (American Mathematical Society (AMS), Boulder, CO, USA, 2006), Vol. 398, pp. 203–231, ISBN: 0-8218-3698-6/pbk . https://doi.org/10.1090/conm/398/07488, Google ScholarCrossref
  16. 16. Kirwin, W. D., Mourão, J., Nunes, J. P., and Qian, T., “Extending coherent state transforms to Clifford analysis,” J. Math. Phys. 57, 103505 (2016). https://doi.org/10.1063/1.4964448, Google ScholarScitation, ISI
  17. 17. Kou, K. I., Qian, T., and Sommen, F., “Generalizations of Fueter’s theorem,” Methods Appl. Anal. 9, 273–289 (2002). https://doi.org/10.4310/maa.2002.v9.n2.a5, Google ScholarCrossref
  18. 18. Li, C., McIntosh, A., and Qian, T., “Clifford algebras, Fourier transforms and singular convolution operators on Lipsschitz surfaces,” Rev. Mat. Iberoam. 19, 665–721 (1994). https://doi.org/10.4171/RMI/164, Google ScholarCrossref
  19. 19. Peña Peña, D., Qian, T., and Sommen, F., “An alternative proof of Fueter’s theorem,” Complex Var. Elliptic Equations 51(8-11), 913–922 (2006). https://doi.org/10.1080/17476930600667650, Google ScholarCrossref
  20. 20. Peña Peña, D. and Sommen, F., “Monogenic Gaussian distribution in closed form and the Gaussian fundamental solution,” Complex Var. Elliptic Equations 54, 429–440 (2009). https://doi.org/10.1080/17476930802669744, Google ScholarCrossref
  21. 21. Qian, T., “Generalization of Fueter’s result to ℝn+1,” Atti Accad. Naz. Lincei Cl. Sci. Fis. Mat. Natur. Rend. Lincei (9) Mat. Appl. 8, 111–117 (1997). Google Scholar
  22. 22. Qian, T., “Fourier analysis on starlike Lipschitz surfaces,” J. Funct. Anal. 183, 370–412 (2001). https://doi.org/10.1006/jfan.2001.3750, Google ScholarCrossref
  23. 23. Segal, I., “Mathematical characterization of the physical vacuum for a linear Bose-Einstein field,” Ill. J. Math. 6, 500–523 (1962). Google ScholarCrossref
  24. 24. Segal, I., “The complex wave representation of the free Boson field,” in Topics in Functional Analysis: Essays Dedicated to M. G. Krein on the Occasion of His 70th Birthday, Advances in Mathematics Supplementary Studies Vol. 3, edited by Gohberg, I. and Kac, M. (Academic Press, New York, 1978), pp. 321–343. Google Scholar
  25. 25. Sommen, F., “Some connections between Clifford analysis and complex analysis,” Complex Var. 1, 97–118 (1982). https://doi.org/10.1080/17476938208814008, Google ScholarCrossref
  26. 26. Souček, V., “Generalized C-R equations on manifolds,” in Clifford Algebras and their Applications in Mathematical Physics, NATO ASI Series C Vol. 183, edited by Chisholm, J. S. R. and Common, A. K. (D. Reidel Publishing Company, 1986). Google ScholarCrossref
  27. Published by AIP Publishing.