Lepton distributions from the decay of scalar-lepton pairs at <span class="aps-inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>e</mi></mrow><mrow><mo>+</mo></mrow></msup></mrow></math></span><span class="aps-inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><msup><mrow><mi>e</mi></mrow><mrow><mi mathvariant="normal">−</mi></mrow></msup></mrow></math></span> colliders

Thomas Schimert; Xerxes Tata

doi:10.1103/PhysRevD.32.721

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Lepton distributions from the decay of scalar-lepton pairs at $e^{+}$ $e^{-}$ colliders

Thomas Schimert

Xerxes Tata

Center for Particle Theory, The University of Texas at Austin, Austin, Texas 78712

Institute of Theoretical Science, University of Oregon, Eugene, Oregon 97403 and Center for Particle Theory, The University of Texas at Austin, Austin, Texas 78712

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Phys. Rev. D 32, 721 – Published 1 August, 1985

DOI: https://doi.org/10.1103/PhysRevD.32.721

Abstract

We have considered the possibility of detecting the scalar lepton at the Stanford Linear Collider or CERN LEP at energies up to 2 $m_{W}$ by studying the energy and angular distributions of dileptons produced via $e^{+}$ $e^{-}$ →l̃ ${}^{+}̃$ ${}^{-}l^{+}$ γ̃ $l^{-}$ γ̃. It is shown that the scalar lepton is characterized by a flat lepton energy spectrum.

References (18)

For recent reviews on the subject, see P. Nath, R. Arnowitt, and A. Chamseddine, lectures at the Summer Workshop on Particle Physics, ICTP, Trieste, Italy, Northeastern University Report No. NUB 2613, 1983 (unpublished); H. Haber and G. Kane, Phys. Rep. 117, 75 (1985); S. Dawson, E. Eichten and C. Quigg, Phys. Rev. D 31, 1581 (1985). See also Ref. 2 and references therein.
T. Schimert, C. Burgess and X. Tata, preceding paper, Phys. Rev. D 31, 707 (1985).
As in Ref. 2, we assume that the photino is essentially massless so that this decay is always allowed. If the Z̃ is light enough, the decay $\tilde{l}$ -> lZ̃ would also be possible as would $ $\tilde{l}$ -> $\tilde{W}$ $\tilde{ν}$ (if $\tilde{ν}$ was also very light). Since the Z̃ and $\tilde{W}$ would dominantly decay into hadrons (see Ref. 4), their contribution to the type of topology discussed is suppressed by factors of the leptonic branching ratio.
D. Dicus, S. Nandi and X. Tata, Phys. Lett. 129B, 451 (1983).
(a) G. R. Farrar and P. Fayet, Phys. Lett. 89B, 191 (1980); (b) M. Glück and F. Reya, 130B, 423 (1983).
R. Barbieri, N. Cabibbo, L. Maiani and S. Petrarca, Phys. Lett. 127B, 458 (1983); R. M. Barnett, H. E. Haber and K. S. Lackner, Phys. Rev. D 29, 1381 (1984). These authors have considered scalar-electron production via the decay of the W.
M. Kuroda et al., Phys. Lett. 127B, 467 (1983). These authors have considered single-scalar-electron production in $e^{+}$ $e^{-}$ collisions.
D. Dicus, S. Nandi, W. Repko and X. Tata, Phys. Rev. Lett. 51, 1030 (1983).
R. Arnowitt, A. Chamseddine and P. Nath, Phys. Rev. Lett. 49, 970 (1982); ibid. 50, 232 (1983).
See Ref. 18 in Ref. 2. Since the Higgs-fermion content of the photino is down by $m_{app from up 50 γ}$ / $m_{& Z t i l d e_{h}}$ , we expect these distributions to be relatively insensitive to our neglect of all Higgs-fermion content in the photino.
The first three terms in Eq. (4b) are due to the gamma and Z exchange and hence are common with ψ ${}_{\tilde{μ}}$ . The remaining terms are due to the t-channel exchanges discussed earlier.
D. Dicus, S. Nandi, W. Repko and X. Tata, Phys. Rev. D 29, 1317 (1984); ibid. 30, 112 (1984).
The model thus has only two new parameters, which we may take to be the $\tilde{W}$ mass and the gravitino mass.
V. Barger, R. W. Rubinett, W.-Y. Keung, and R. J. N. Phillips, Phys. Rev. D 28, 2912 (1983).
If the $\tilde{W}$ was significantly lighter, it would be expected to be seen in the direct production of $\tilde{W}$ pairs. See, for example, Ref. 2 and Ref. 8.
This has to be doubled in order to take into account lepton production due to ẽ ${}_{L}^{back}13$ +ẽ ${}_{R}^{back}13$ - and ẽ ${}_{R}^{back}13$ +ẽ ${}_{L}^{back}13$ -.
J. Ellis et al., Phys. Lett. 132B, 463 (1983).
The total cross section for ${ẽ}_{L ẽ sub}$ R production can be quite comparable to the ${ẽ}_{L ẽ sub}$ L production if the interference term between the Z̃ and $\tilde{γ}$ is constructive. For example, for $m_{app from up 50 γ}$ = 3 GeV, $m_{\tilde{W}}$ = 30 GeV, and $m_{g}$ = 25 GeV, it is about 40% that of the ${ẽ}_{L ẽ sub}$ L production whereas for the same parameters, changing the sign of the interference term reduces it by almost an order of magnitude. Since these rates are very sensitively dependent on the model (through the mass matrix for neutral gauge and Higgs fermions) and also on the value of the photino mass, we did not see fit to present detailed numerical results for this process here. It is, however, straightforward to include the photino terms in Eq. (10) given any specific model.

[c1] For recent reviews on the subject, see P. Nath, R. Arnowitt, and A. Chamseddine, lectures at the Summer Workshop on Particle Physics, ICTP, Trieste, Italy, Northeastern University Report No. NUB 2613, 1983 (unpublished); H. Haber and G. Kane, Phys. Rep. 117, 75 (1985); S. Dawson, E. Eichten and C. Quigg, Phys. Rev. D 31, 1581 (1985). See also Ref. 2 and references therein.

[c2] T. Schimert, C. Burgess and X. Tata, preceding paper, Phys. Rev. D 31, 707 (1985).

[c3] As in Ref. 2, we assume that the photino is essentially massless so that this decay is always allowed. If the Z̃ is light enough, the decay $\tilde{l}$ -> lZ̃ would also be possible as would $ $\tilde{l}$ -> $\tilde{W}$ $\tilde{ν}$ (if $\tilde{ν}$ was also very light). Since the Z̃ and $\tilde{W}$ would dominantly decay into hadrons (see Ref. 4), their contribution to the type of topology discussed is suppressed by factors of the leptonic branching ratio.

[c4] D. Dicus, S. Nandi and X. Tata, Phys. Lett. 129B, 451 (1983).

[c5] (a) G. R. Farrar and P. Fayet, Phys. Lett. 89B, 191 (1980); (b) M. Glück and F. Reya, 130B, 423 (1983).

[c6] R. Barbieri, N. Cabibbo, L. Maiani and S. Petrarca, Phys. Lett. 127B, 458 (1983); R. M. Barnett, H. E. Haber and K. S. Lackner, Phys. Rev. D 29, 1381 (1984). These authors have considered scalar-electron production via the decay of the W.

[c7] M. Kuroda et al., Phys. Lett. 127B, 467 (1983). These authors have considered single-scalar-electron production in $e^{+}$ $e^{-}$ collisions.

[c8] D. Dicus, S. Nandi, W. Repko and X. Tata, Phys. Rev. Lett. 51, 1030 (1983).

[c9] R. Arnowitt, A. Chamseddine and P. Nath, Phys. Rev. Lett. 49, 970 (1982); ibid. 50, 232 (1983).

[c10] See Ref. 18 in Ref. 2. Since the Higgs-fermion content of the photino is down by $m_{app from up 50 γ}$ / $m_{& Z t i l d e_{h}}$ , we expect these distributions to be relatively insensitive to our neglect of all Higgs-fermion content in the photino.

[c11] The first three terms in Eq. (4b) are due to the gamma and Z exchange and hence are common with ψ ${}_{\tilde{μ}}$ . The remaining terms are due to the t-channel exchanges discussed earlier.

[c12] D. Dicus, S. Nandi, W. Repko and X. Tata, Phys. Rev. D 29, 1317 (1984); ibid. 30, 112 (1984).

[c13] The model thus has only two new parameters, which we may take to be the $\tilde{W}$ mass and the gravitino mass.

[c14] V. Barger, R. W. Rubinett, W.-Y. Keung, and R. J. N. Phillips, Phys. Rev. D 28, 2912 (1983).

[c15] If the $\tilde{W}$ was significantly lighter, it would be expected to be seen in the direct production of $\tilde{W}$ pairs. See, for example, Ref. 2 and Ref. 8.

[c16] This has to be doubled in order to take into account lepton production due to ẽ ${}_{L}^{back}13$ +ẽ ${}_{R}^{back}13$ - and ẽ ${}_{R}^{back}13$ +ẽ ${}_{L}^{back}13$ -.

[c17] J. Ellis et al., Phys. Lett. 132B, 463 (1983).

[c18] The total cross section for ${ẽ}_{L ẽ sub}$ R production can be quite comparable to the ${ẽ}_{L ẽ sub}$ L production if the interference term between the Z̃ and $\tilde{γ}$ is constructive. For example, for $m_{app from up 50 γ}$ = 3 GeV, $m_{\tilde{W}}$ = 30 GeV, and $m_{g}$ = 25 GeV, it is about 40% that of the ${ẽ}_{L ẽ sub}$ L production whereas for the same parameters, changing the sign of the interference term reduces it by almost an order of magnitude. Since these rates are very sensitively dependent on the model (through the mass matrix for neutral gauge and Higgs fermions) and also on the value of the photino mass, we did not see fit to present detailed numerical results for this process here. It is, however, straightforward to include the photino terms in Eq. (10) given any specific model.

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Lepton distributions from the decay of scalar-lepton pairs at $e^{+}$ $e^{-}$ colliders

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Lepton distributions from the decay of scalar-lepton pairs at $e^{+}$ $e^{-}$ colliders