Probing <i>CP</i> violation via Higgs boson decays to four leptons

A. Soni; R. M. Xu

doi:10.1103/PhysRevD.48.5259

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Probing CP violation via Higgs boson decays to four leptons

A. Soni

R. M. Xu

Department of Physics, Brookhaven National Laboratory, Upton, New York 11793

Institute for Theoretical Physics, State University of New York at Stony Brook, Stony Brook, New York 11794-3840

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Phys. Rev. D 48, 5259 – Published 1 December, 1993

DOI: https://doi.org/10.1103/PhysRevD.48.5259

Abstract

Since decays to four leptons is widely considered a promising way to search for the Higgs particle, we show how the same final state can also be used to search for signals of CP nonconservation. Energy asymmetries and triple correlations are related to parameters in the underlying CP-violating effective interaction at the $H^{0}$ -W-W and $H^{0 -}$ Z-Z vertices. It is argued that the expected size of the effects is extremely small in the standard model, and it is shown that the result also seems small to be observable in an extension of the standard model with an extra Higgs doublet.

References (15)

M. Kobayashi and T. Maskawa, Prog. Theor. Phys. 49, 652 (1973).
See, e.g., S. Barr, G. Segre` and H. A. Weldon, Phys. Rev. D 20, 2494 (1979); N. Turok and J. Zadrozny, Phys. Rev. Lett. 65, 231 (1990); L. McLerran, M. Shaposhnikov, N. Turok and M. Voloshin, Phys. Lett. B 256, 451 (1991); M. Dine, P. Huet, R. Singleton and L. Susskind, Nucl. Phys. B358, 471 (1991); A. E. Nelson, D. B. Kaplan and A. G. Cohen, ibid. B373, 453 (1992).
Processes with $Z^{star}$ $γ^{star}$ and $γ^{star}$ $γ^{star}$ intermediate states may also be considered. These could be important for relatively light Higgs bosons which are not the primary focus in this paper.
V. Barger, G. Bhattacharya, T. Han and B. A. Kniehl, Phys. Rev. D 43, 779 (1991); see also W.-Y. Keung and W. J. Marciano, ibid. 30, 248 (1984).
In quoting these numbers, we have assumed that $m_{t}$ is around 130 GeV and $m_{H}$ is about 300 GeV. For a review, see, e.g., E. Eichten, I. Hinchliffe, K. Lane and C. Quigg, Rev. Mod. Phys. 56, 579 (1984); V. Barger and R. J. N. Phillips, Collider Physics (Addison-Wesley, Reading, MA, 1987); J. F. Gunion, H. Haber, G. Kane, and S. Dawson, Higgs Hunter's Guide (Addison-Wesley, Reading, MA, 1991).
See, e.g., G. Valencia and A. Soni, Phys. Lett. B 263, 517 (1991); C. R. Schmidt and M. E. Peskin, Phys. Rev. Lett. 69, 410 (1992).
C. N. Yang, Phys. Rev. 77, 242 (1950); ibid. 77, 722 (1950).
J. R. Dell'Aquila and C. A. Nelson, Phys. Rev. D 33, 80 (1985).
Using an effective interaction similar to Eq. (6), CP violation in $Z^{0}$ -> $H^{0 \bar{f} f}$ has been considered by R. Rattazzl, Z. Phys. C 40, 605 (1988).
Equation (7) is not true for process (III) when the two lepton pairs are identical, because the interference term is not taken into account here. However, when we consider the on-shell case, i.e., Eq. (9), interference effect is expected to be minimal. This is based on the corresponding discussion in T. Miyazaki and E. Takasugi $π^{0}$ and $K_{L}$ decays to four leptons. In this regard see , Phys. Rev. D 8, 2051 (1973).
For the parity-violating coefficient $λ_{1}$ see M. J. Duncan, G. J. Kane and W. W. Repko, Nucl. Phys. B272, 517 (1986); T. Matsura and J. J. Van der Bij, Z. Phys. C 51, 259 (1991); H. Pois, T. J. Weiler and T. C. Yuan, Phys. Rev. D 47, 3886 (1993).
C. Jarlskog, in CP Violation, edited by C. Jarlskog (World Scientific, Singapore, 1989), p. 3.
G. C. Branco and M. N. Rebelo, Phys. Lett. 160B, 117 (1985); J. Liu and L. Wolfenstein, Nucl. Phys. B289, 1 (1987); S. Weinberg, Phys. Rev. D 42, 860 (1990).
D. Chang and W.-Y. Keung, Phys. Lett. B 305, 261 (1993).
B. Grzadkowski and J. F. Gunion, Phys. Lett. B 294, 361 (1992).

[c1] M. Kobayashi and T. Maskawa, Prog. Theor. Phys. 49, 652 (1973).

[c2] See, e.g., S. Barr, G. Segre` and H. A. Weldon, Phys. Rev. D 20, 2494 (1979); N. Turok and J. Zadrozny, Phys. Rev. Lett. 65, 231 (1990); L. McLerran, M. Shaposhnikov, N. Turok and M. Voloshin, Phys. Lett. B 256, 451 (1991); M. Dine, P. Huet, R. Singleton and L. Susskind, Nucl. Phys. B358, 471 (1991); A. E. Nelson, D. B. Kaplan and A. G. Cohen, ibid. B373, 453 (1992).

[c3] Processes with $Z^{star}$ $γ^{star}$ and $γ^{star}$ $γ^{star}$ intermediate states may also be considered. These could be important for relatively light Higgs bosons which are not the primary focus in this paper.

[c4] V. Barger, G. Bhattacharya, T. Han and B. A. Kniehl, Phys. Rev. D 43, 779 (1991); see also W.-Y. Keung and W. J. Marciano, ibid. 30, 248 (1984).

[c5] In quoting these numbers, we have assumed that $m_{t}$ is around 130 GeV and $m_{H}$ is about 300 GeV. For a review, see, e.g., E. Eichten, I. Hinchliffe, K. Lane and C. Quigg, Rev. Mod. Phys. 56, 579 (1984); V. Barger and R. J. N. Phillips, Collider Physics (Addison-Wesley, Reading, MA, 1987); J. F. Gunion, H. Haber, G. Kane, and S. Dawson, Higgs Hunter's Guide (Addison-Wesley, Reading, MA, 1991).

[c6] See, e.g., G. Valencia and A. Soni, Phys. Lett. B 263, 517 (1991); C. R. Schmidt and M. E. Peskin, Phys. Rev. Lett. 69, 410 (1992).

[c7] C. N. Yang, Phys. Rev. 77, 242 (1950); ibid. 77, 722 (1950).

[c8] J. R. Dell'Aquila and C. A. Nelson, Phys. Rev. D 33, 80 (1985).

[c9] Using an effective interaction similar to Eq. (6), CP violation in $Z^{0}$ -> $H^{0 \bar{f} f}$ has been considered by R. Rattazzl, Z. Phys. C 40, 605 (1988).

[c10] Equation (7) is not true for process (III) when the two lepton pairs are identical, because the interference term is not taken into account here. However, when we consider the on-shell case, i.e., Eq. (9), interference effect is expected to be minimal. This is based on the corresponding discussion in T. Miyazaki and E. Takasugi $π^{0}$ and $K_{L}$ decays to four leptons. In this regard see , Phys. Rev. D 8, 2051 (1973).

[c11] For the parity-violating coefficient $λ_{1}$ see M. J. Duncan, G. J. Kane and W. W. Repko, Nucl. Phys. B272, 517 (1986); T. Matsura and J. J. Van der Bij, Z. Phys. C 51, 259 (1991); H. Pois, T. J. Weiler and T. C. Yuan, Phys. Rev. D 47, 3886 (1993).

[c12] C. Jarlskog, in CP Violation, edited by C. Jarlskog (World Scientific, Singapore, 1989), p. 3.

[c13] G. C. Branco and M. N. Rebelo, Phys. Lett. 160B, 117 (1985); J. Liu and L. Wolfenstein, Nucl. Phys. B289, 1 (1987); S. Weinberg, Phys. Rev. D 42, 860 (1990).

[c14] D. Chang and W.-Y. Keung, Phys. Lett. B 305, 261 (1993).

[c15] B. Grzadkowski and J. F. Gunion, Phys. Lett. B 294, 361 (1992).

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Probing CP violation via Higgs boson decays to four leptons

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