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Search for neutral Higgs bosons decaying into four taus at LEP2

ALEPH Collaboration, S. Schael, R. Barate, R. Brunelière, I. De Bonis, D. Decamp, C. Goy, S. Jézéquel, J. -P. Lees, F. Martin, E. Merle, M. -N. Minard, B. Pietrzyk, B. Trocmé S. Bravo, M. P. Casado, M. Chmeissani, J. M. Crespo, E. Fernandez, M. Fernandez-Bosman, Ll. Garrido, M. Martinez, A. Pacheco, H. Ruiz, A. Colaleo, D. Creanza, N. De Filippis, M. de Palma, G. Iaselli, G. Maggi, M. Maggi, S. Nuzzo, A. Ranieri, G. Raso, F. Ruggieri, G. Selvaggi, L. Silvestris, P. Tempesta, A. Tricomi, G. Zito X. Huang, J. Lin, Q. Ouyang, T. Wang, Y. Xie, R. Xu, S. Xue, J. Zhang, L. Zhang, W. Zhao, D. Abbaneo, T. Barklow, O. Buchmüller, M. Cattaneo, B. Clerbaux, H. Drevermann, R. W. Forty, M. Frank, F. Gianotti, J. B. Hansen, J. Harvey, D. E. Hutchcroft, P. Janot, B. Jost, M. Kado, P. Mato, A. Moutoussi, F. Ranjard, L. Rolandi, D. Schlatter, F. Teubert, A. Valassi, I. Videau S. Monteil, D. Pallin, J. M. Pascolo, P. Perret, J. D. Hansen, J. R. Hansen, P. H. Hansen, A. C. Kraan, B. S. Nilsson A. Kyriakis, C. Markou, E. Simopoulou, A. Vayaki, K. Zachariadou A. Blondel, J. -C. Brient, F. Machefert, A. Rougé, H. Videau, V. Ciulli, E. Focardi, G. Parrini, A. Antonelli, M. Antonelli, G. Bencivenni, F. Bossi, G. Capon, F. Cerutti, V. Chiarella, P. Laurelli, G. Mannocchi, G. P. Murtas, L. Passalacqua, J. Kennedy, J. G. Lynch, P. Negus, V. O'Shea, A. S. Thompson, R. Cavanaugh, S. Dhamotharan, C. Geweniger, P. Hanke, V. Hepp, E. E. Kluge, A. Putzer, H. Stenzel, K. Tittel, M. Wunsch, R. Beuselinck, W. Cameron, G. Davies, P. J. Dornan, M. Girone, N. Marinelli, J. Nowell, S. A. Rutherford, J. K. Sedgbeer, J. C. Thompson, R. White, V. M. Ghete, P. Girtler, E. Kneringer, D. Kuhn, G. Rudolph, E. Bouhova-Thacker, C. K. Bowdery, D. P. Clarke, G. Ellis, A. J. Finch, F. Foster, G. Hughes, R. W. L. Jones, M. R. Pearson, N. A. Robertson, T. Sloan, M. Smizanska, O. van der Aa, C. Delaere, G. Leibenguth, V. Lemaitre U. Blumenschein, F. Hölldorfer, K. Jakobs, F. Kayser, A. -S. Müller, B. Renk, H. -G. Sander, S. Schmeling, H. Wachsmuth, C. Zeitnitz, T. Ziegler A. Bonissent, P. Coyle, C. Curtil, A. Ealet, D. Fouchez, P. Payre, A. Tilquin, F. Ragusa, A. David, H. Dietl, G. Ganis, K. Hüttmann, G. Lütjens, W. Männer H. -G. Moser, R. Settles, M. Villegas, G. Wolf, J. Beacham, K. Cranmer I. Yavin, J. Boucrot, O. Callot, M. Davier, L. Duflot, J. -F. Grivaz, Ph. Heusse, A. Jacholkowska, L. Serin, J. -J. Veille, P. Azzurri, G. Bagliesi, T. Boccali, L. Foà, A. Giammanco, A. Giassi, F. Ligabue, A. Messineo, F. Palla, G. Sanguinetti, A. Sciabà, G. Sguazzoni, P. Spagnolo, R. Tenchini, A. Venturi, P. G. Verdini O. Awunor, G. A. Blair, G. Cowan, A. Garcia-Bellido, M. G. Green, T. Medcalf, A. Misiejuk, J. A. Strong, P. Teixeira-Dias, R. W. Clifft, T. R. Edgecock, P. R. Norton, I. R. Tomalin, J. J. Ward B. Bloch-Devaux, D. Boumediene, P. Colas, B. Fabbro, E. Lançon, M. -C. Lemaire, E. Locci, P. Perez, J. Rander, B. Tuchming, B. Vallage, A. M. Litke, G. Taylor, C. N. Booth, S. Cartwright, F. Combley, P. N. Hodgson, M. Lehto, L. F. Thompson, A. Böhrer, S. Brandt, C. Grupen, J. Hess, A. Ngac, G. Prange C. Borean, G. Giannini, H. He, J. Putz, J. Rothberg, S. R. Armstrong, K. Berkelman, D. P. S. Ferguson, Y. Gao, S. González, O. J. Hayes, H. Hu, S. Jin, J. Kile, P. A. McNamara, J. Nielsen, Y. B. Pan, J. H. von Wimmersperg-Toeller, W. Wiedenmann, J. Wu, Sau Lan Wu, X. Wu, G. Zobernig, G. Dissertori

TL;DR

Problem addressed: testing non-standard Higgs decays h→aa→4τ in e+e− collisions at LEP2. Approach: analyze 683 pb−1 of ALEPH data at 183–209 GeV, simulate signal with hzha03 and backgrounds with GEANT3-based tools across three Z decay channels, and extract limits on ξ^2 using a joint likelihood. Key findings: no excess observed; exclude ξ^2>1 for mh<107 GeV/c^2 and 4<ma<10 GeV/c^2 at 95% CL. Significance: constrains NMSSM-like models with h→2a decays and adds model-independent limits on non-standard Higgsstrahlung decays.

Abstract

A search for the production and non-standard decay of a Higgs boson, h, into four taus through intermediate pseudoscalars, a, is conducted on 683 pb-1 of data collected by the ALEPH experiment at centre-of-mass energies from 183 to 209 GeV. No excess of events above background is observed, and exclusion limits are placed on the combined production cross section times branching ratio, ξ^2 = σ(e+e- --> Zh)/σ_{SM}(e+e- --> Zh) x B(h --> aa)x B(a --> τ^+τ^-)^2. For mh < 107 GeV/c2 and 4 < ma < 10 GeV/c2, ξ^2 > 1 is excluded at the 95% confidence level.

Search for neutral Higgs bosons decaying into four taus at LEP2

TL;DR

Problem addressed: testing non-standard Higgs decays h→aa→4τ in e+e− collisions at LEP2. Approach: analyze 683 pb−1 of ALEPH data at 183–209 GeV, simulate signal with hzha03 and backgrounds with GEANT3-based tools across three Z decay channels, and extract limits on ξ^2 using a joint likelihood. Key findings: no excess observed; exclude ξ^2>1 for mh<107 GeV/c^2 and 4<ma<10 GeV/c^2 at 95% CL. Significance: constrains NMSSM-like models with h→2a decays and adds model-independent limits on non-standard Higgsstrahlung decays.

Abstract

A search for the production and non-standard decay of a Higgs boson, h, into four taus through intermediate pseudoscalars, a, is conducted on 683 pb-1 of data collected by the ALEPH experiment at centre-of-mass energies from 183 to 209 GeV. No excess of events above background is observed, and exclusion limits are placed on the combined production cross section times branching ratio, ξ^2 = σ(e+e- --> Zh)/σ_{SM}(e+e- --> Zh) x B(h --> aa)x B(a --> τ^+τ^-)^2. For mh < 107 GeV/c2 and 4 < ma < 10 GeV/c2, ξ^2 > 1 is excluded at the 95% confidence level.

Paper Structure

This paper contains 10 sections, 1 equation, 6 figures, 3 tables.

Table of Contents

  1. Introduction
  2. The ALEPH Detector
  3. Signal and Background Generation
  4. Event Selection
  5. $\mathrm{Z}\rightarrow \ell^+\ell^-$
  6. $\mathrm{Z}\rightarrow \nu\bar{\nu}$
  7. Signal Efficiency
  8. Systematic Uncertainties
  9. Results
  10. Conclusions

Figures (6)

  • Figure 1: Higgs boson production and decay modes considered in this analysis.
  • Figure 2: Distributions for the $\mathrm{Z}\rightarrow \mathrm{e}^+\mathrm{e}^-$ channel after the loose selection for (a) the reconstructed $\mathrm{Z}$ invariant mass and (b) missing energy, where signal corresponds to $m_\mathrm{h} = 100~\hbox{$\mathrm{GeV}/{{\it c}^2}$}$, $m_\mathrm{a} = 4~\hbox{$\mathrm{GeV}/{{\it c}^2}$}$ with $\xi^2=1$ (see text). The same distributions are shown in (c) and (d) after the final selection, excluding any requirements on the variable shown.
  • Figure 3: Distributions for the $\mathrm{Z}\rightarrow \mu^+\mu^-$ channel after the loose selection for (a) the reconstructed $\mathrm{Z}$ invariant mass and (b) missing energy, where signal corresponds to $m_\mathrm{h} = 100~\hbox{$\mathrm{GeV}/{{\it c}^2}$}$, $m_\mathrm{a} = 4~\hbox{$\mathrm{GeV}/{{\it c}^2}$}$ with $\xi^2=1$ (see text). The same distributions are shown in (c) and (d) after the final selection, excluding any requirements on the variable shown.
  • Figure 4: Distributions for the $\mathrm{Z}\rightarrow \nu\bar{\nu}$ channel after the loose selection and requirement of $1<n^\mathrm{track}_2 < 7$ for (a) dijet invariant mass and (b) missing mass, where signal corresponds to $m_\mathrm{h} = 100~\hbox{$\mathrm{GeV}/{{\it c}^2}$}$, $m_\mathrm{a} = 4~\hbox{$\mathrm{GeV}/{{\it c}^2}$}$ with $\xi^2=1$ (see text). The same distributions are shown in (c) and (d) after the final selection, excluding any requirements on the variable shown.
  • Figure 5: Signal efficiency as a function of the Higgs boson mass for the three channels considered in this work, $\mathrm{Z}\rightarrow \mathrm{e}^+\mathrm{e}^-,~\mu^+\mu^-,$ and $\nu\bar{\nu}$. The upper (lower) portion of the efficiency band corresponds to $m_\mathrm{a} = 4 ~(10)~\hbox{$\mathrm{GeV}/{{\it c}^2}$}$.
  • ...and 1 more figures