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Distinguishing ‘Higgs’ spin hypotheses using γγ and WW ∗ decays

  • Regular Article - Theoretical Physics
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Abstract

The new particle X recently discovered by the ATLAS and CMS Collaborations in searches for the Higgs boson has been observed to decay into γγ, ZZ ∗ and WW ∗, but its spin and parity, J P, remain a mystery, with J P=0+ and 2+ being open possibilities. We use PYTHIA and Delphes to simulate an analysis of the angular distribution of gg→X→γγ decays in a full 2012 data set, including realistic background levels. We show that this angular distribution should provide strong discrimination between the possibilities of spin zero and spin two with graviton-like couplings: ∼3σ if a conservative symmetric interpretation of the log-likelihood ratio (LLR) test statistic is used, and ∼6σ if a less conservative asymmetric interpretation is used. The WW and ZZ couplings of the Standard Model Higgs boson and of a 2+ particle with graviton-like couplings are both expected to exhibit custodial symmetry. We simulate the present ATLAS and CMS search strategies for X→WW ∗ using PYTHIA and Delphes, and show that their efficiencies in the case of a spin-2 particle with graviton-like couplings are a factor ≃1.9 smaller than in the spin-0 case. On the other hand, the ratio of \(X_{2^{+}} \to W W^{\ast}\) and ZZ ∗ branching ratios is larger than that in the 0+ case by a factor ≃1.3. We find that the current ATLAS and CMS results for X→WW ∗ and X→ZZ ∗ decays are compatible with custodial symmetry under both the spin-0 and -2 hypotheses, and that the data expected to become available during 2012 are unlikely to discriminate significantly between these possibilities.

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Notes

  1. We note that in flat extra dimensions one typically finds conservation of a Kaluza–Klein parity that would forbid the coupling of the massive graviton to two light Standard Model particles.

  2. To the extent that these other production mechanisms are suppressed relative to gg→X, their inclusion or omission is not important. We have checked that their inclusion in our simulation does not affect significantly the angular distributions from gg→X alone.

  3. We define \(p_{Tt} \equiv|\vec{p}_{T}^{\gamma \gamma} \times\vec{t}|\), where the thrust vector is defined as \(\vec{t} \equiv(\vec{p}_{T}^{\gamma_{1}}-\vec{p}_{T}^{\gamma_{1}})/|\vec {p}_{T}^{\gamma_{1}}+\vec{p}_{T}^{\gamma_{1}}|\).

  4. For a discussion of the relative merits of the LLR and the asymmetry variable, see [77].

  5. This is the one-sided definition most commonly used in the literature, as opposed to the two-sided convention sometimes seen, which generally yields a higher number of standard deviations for the same p-value.

  6. Adding a 1 % error in N tot does not affect the results.

  7. We implement the relevant quality and isolation criteria at the level of the Delphes simulation.

  8. We cannot use for this purpose the value of λ WZ quoted in [84], because this incorporates information from a combination of channels including X→γγ, which supplies information on a W that does not apply to the spin-2 case.

References

  1. G. Aad et al. (ATLAS Collaboration), Phys. Lett. B 716, 1 (2012). arXiv:1207.7214 [hep-ex]

    Article  ADS  Google Scholar 

  2. F. Gianotti, Talk on behalf of the ATLAS Collaboration at CERN, 4th July (2012). https://cms-docdb.cern.ch/cgi-bin/PublicDocDB//ShowDocument?docid=6126

  3. S. Chatrchyan et al. (CMS Collaboration), Phys. Lett. B 716, 30 (2012). arXiv:1207.7235 [hep-ex]

    Article  ADS  Google Scholar 

  4. J. Incandela, Talk on behalf of the CMS Collaboration at CERN, 4th July (2012). https://cms-docdb.cern.ch/cgi-bin/PublicDocDB//ShowDocument?docid=6125

  5. L.D. Landau, Dokl. Akad. Nauk Ser. Fiz. 60, 207 (1948)

    Google Scholar 

  6. C.-N. Yang, Phys. Rev. 77, 242 (1950)

    Article  ADS  MATH  Google Scholar 

  7. J. Ellis, T. You, J. High Energy Phys. 1209, 123 (2012). arXiv:1207.1693 [hep-ph]

    Article  ADS  Google Scholar 

  8. D. Carmi, A. Falkowski, E. Kuflik, T. Volanski. arXiv:1202.3144 [hep-ph]

  9. A. Azatov, R. Contino, J. Galloway, J. High Energy Phys. 1204, 127 (2012). arXiv:1202.3415 [hep-ph]

    Article  ADS  Google Scholar 

  10. J.R. Espinosa, C. Grojean, M. Muhlleitner, M. Trott, arXiv:1202.3697 [hep-ph]

  11. P.P. Giardino, K. Kannike, M. Raidal, A. Strumia, arXiv:1203.4254 [hep-ph]

  12. T. Li, X. Wan, Y. Wang, S. Zhu, arXiv:1203.5083 [hep-ph]

  13. M. Rauch, arXiv:1203.6826 [hep-ph]

  14. J. Ellis, T. You, J. High Energy Phys. 1206, 140 (2012). arXiv:1204.0464 [hep-ph]

    Article  ADS  Google Scholar 

  15. A. Azatov, R. Contino, D. Del Re, J. Galloway, M. Grassi, S. Rahatlou, arXiv:1204.4817 [hep-ph]

  16. M. Klute, R. Lafaye, T. Plehn, M. Rauch, D. Zerwas, arXiv:1205.2699 [hep-ph]

  17. J.R. Espinosa, M. Muhlleitner, C. Grojean, M. Trott, arXiv:1205.6790 [hep-ph]

  18. D. Carmi, A. Falkowski, E. Kuflik, T. Volansky, arXiv:1206.4201 [hep-ph]

  19. M.J. Dolan, C. Englert, M. Spannowsky, arXiv:1206.5001 [hep-ph]

  20. J. Chang, K. Cheung, P. Tseng, T. Yuan, arXiv:1206.5853 [hep-ph]

  21. S. Chang, C.A. Newby, N. Raj, C. Wanotayaroj, arXiv:1207.0493 [hep-ph]

  22. I. Low, J. Lykken, G. Shaughnessy, arXiv:1207.1093 [hep-ph]

  23. T. Corbett, O.J.P. Eboli, J. Gonzalez-Fraile, M.C. Gonzalez-Garcia, arXiv:1207.1344 [hep-ph]

  24. P.P. Giardino, K. Kannike, M. Raidal, A. Strumia, arXiv:1207.1347 [hep-ph]

  25. M. Montull, F. Riva, arXiv:1207.1716 [hep-ph]

  26. J.R. Espinosa, C. Grojean, M. Muhlleitner, M. Trott, arXiv:1207.1717 [hep-ph]

  27. D. Carmi, A. Falkowski, E. Kuflik, T. Volansky, J. Zupan, arXiv:1207.1718 [hep-ph]

  28. S. Banerjee, S. Mukhopadhyay, B. Mukhopadhyaya, J. High Energy Phys. 10, 062 (2012). arXiv:1207.3588 [hep-ph]

    Article  ADS  Google Scholar 

  29. F. Bonner, T. Ota, M. Rauch, W. Winter, arXiv:1207.4599 [hep-ph]

  30. T. Plehn, M. Rauch, arXiv:1207.6108 [hep-ph]

  31. A. Djouadi, arXiv:1208.3436 [hep-ph]

  32. B. Batell, S. Gori, L.T. Wang, arXiv:1209.6832 [hep-ph]

  33. T. Aaltonen et al. (CDF and D0 Collaborations), arXiv:1207.6436 [hep-ex]

  34. TEVNPH Working Group, for the CDF and D0 Collaborations, arXiv:1207.0449 [hep-ex]

  35. J. Ellis, D.S. Hwang, V. Sanz, T. You, arXiv:1208.6002 [hep-ph]

  36. J.R. Dell’Aquila, C.A. Nelson, Nucl. Phys. B 320, 61 (1989)

    Article  ADS  Google Scholar 

  37. J.R. Dell’Aquila, C.A. Nelson, Phys. Rev. D 33, 80 (1986)

    Article  ADS  Google Scholar 

  38. J.R. Dell’Aquila, C.A. Nelson, Phys. Rev. D 33, 93 (1986)

    Article  ADS  Google Scholar 

  39. J.R. Dell’Aquila, C.A. Nelson, Phys. Rev. D 33, 101 (1986)

    Article  ADS  Google Scholar 

  40. J.R. Dell’Aquila, C.A. Nelson, Nucl. Phys. B 320, 86 (1989)

    Article  ADS  Google Scholar 

  41. S.Y. Choi, D.J. Miller, M.M. Muhlleitner, P.M. Zerwas, Phys. Lett. B 553, 61 (2003). arXiv:hep-ph/0210077

    Article  ADS  Google Scholar 

  42. K. Odagiri, J. High Energy Phys. 0303, 009 (2003). arXiv:hep-ph/0212215

    Article  ADS  Google Scholar 

  43. C.P. Buszello, I. Fleck, P. Marquard, J.J. van der Bij, Eur. Phys. J. C 32, 209 (2004). arXiv:hep-ph/0212396

    Article  ADS  Google Scholar 

  44. A. Djouadi, Phys. Rep. 457, 1 (2008). arXiv:hep-ph/0503172

    Article  ADS  Google Scholar 

  45. C.P. Buszello, P. Marquard, arXiv:hep-ph/0603209

  46. A. Bredenstein, A. Denner, S. Dittmaier, M.M. Weber, Phys. Rev. D 74, 013004 (2006). arXiv:hep-ph/0604011

    Article  ADS  Google Scholar 

  47. P.S. Bhupal Dev, A. Djouadi, R.M. Godbole, M.M. Muhlleitner, S.D. Rindani, Phys. Rev. Lett. 100, 051801 (2008). arXiv:0707.2878 [hep-ph]

    Article  ADS  Google Scholar 

  48. R.M. Godbole, D.J. Miller, M.M. Muhlleitner, J. High Energy Phys. 0712, 031 (2007). arXiv:0708.0458 [hep-ph]

    Article  ADS  Google Scholar 

  49. K. Hagiwara, Q. Li, K. Mawatari, J. High Energy Phys. 0907, 101 (2009). arXiv:0905.4314 [hep-ph]

    Article  ADS  Google Scholar 

  50. A. De Rujula, J. Lykken, M. Pierini, C. Rogan, M. Spiropulu, Phys. Rev. D 82, 013003 (2010). arXiv:1001.5300 [hep-ph]

    Article  ADS  Google Scholar 

  51. C. Englert, C. Hackstein, M. Spannowsky, Phys. Rev. D 82, 114024 (2010). arXiv:1010.0676 [hep-ph]

    Article  ADS  Google Scholar 

  52. U. De Sanctis, M. Fabbrichesi, A. Tonero, Phys. Rev. D 84, 015013 (2011). arXiv:1103.1973 [hep-ph]

    Article  ADS  Google Scholar 

  53. V. Barger, P. Huang, Phys. Rev. D 84, 093001 (2011). arXiv:1107.4131 [hep-ph]

    Article  ADS  Google Scholar 

  54. S. Bolognesi, Y. Gao, A.V. Gritsan, K. Melnikov, M. Schulze, N.V. Tran, A. Whitbeck, arXiv:1208.4018 [hep-ph]

  55. R. Boughezal, T.J. LeCompte, F. Petriello, arXiv:1208.4311 [hep-ph]

  56. D. Stolarski, R. Vega-Morales, arXiv:1208.4840 [hep-ph]

  57. S.Y. Choi, M.M. Muhlleitner, P.M. Zerwas, arXiv:1209.5268 [hep-ph]

  58. R. Fok, C. Guimaraes, R. Lewis, V. Sanz, arXiv:1203.2917 [hep-ph]

  59. C. Csaki, C. Grojean, H. Murayama, L. Pilo, J. Terning, Phys. Rev. D 69, 055006 (2004). hep-ph/0305237

    Article  ADS  Google Scholar 

  60. T. Gherghetta, A. Pomarol, Nucl. Phys. B 586, 141 (2000). hep-ph/0003129

    Article  MathSciNet  ADS  MATH  Google Scholar 

  61. T. Gherghetta, A. Pomarol, Nucl. Phys. B 602, 3 (2001). hep-ph/0012378

    Article  ADS  MATH  Google Scholar 

  62. L. Randall, V. Sanz, M.D. Schwartz, J. High Energy Phys. 0206, 008 (2002). hep-th/0204038

    Article  MathSciNet  ADS  Google Scholar 

  63. J. Hirn, V. Sanz, Phys. Rev. D 76, 044022 (2007). hep-ph/0702005

    Article  MathSciNet  ADS  Google Scholar 

  64. J. Hirn, V. Sanz, Phys. Rev. Lett. 97, 121803 (2006). hep-ph/0606086

    Article  ADS  Google Scholar 

  65. J. Hirn, V. Sanz, J. High Energy Phys. 0703, 100 (2007). hep-ph/0612239

    Article  ADS  Google Scholar 

  66. S. Eidelman et al. (Particle Data Group Collaboration), Phys. Lett. B 592, 1 (2004)

    Article  ADS  Google Scholar 

  67. A.L. Fitzpatrick, J. Kaplan, L. Randall, L.-T. Wang, J. High Energy Phys. 0709, 013 (2007). hep-ph/0701150

    Article  MathSciNet  ADS  Google Scholar 

  68. Y. Grossman, M. Neubert, Phys. Lett. B 474, 361 (2000). hep-ph/9912408

    Article  MathSciNet  ADS  MATH  Google Scholar 

  69. Y. Gao, A.V. Gritsan, Z. Guo, K. Melnikov, M. Schulze, N.V. Tran, Phys. Rev. D 81, 075022 (2010). arXiv:1001.3396 [hep-ph]

    Article  ADS  Google Scholar 

  70. V.D. Barger, G. Bhattacharya, T. Han, B.A. Kniehl, Phys. Rev. D 43, 779 (1991)

    Article  ADS  Google Scholar 

  71. M. Dittmar, H. Dreiner, CMS-NOTE-1997-083

  72. M. Dittmar, H.K. Dreiner, Phys. Rev. D 55, 167 (1997). hep-ph/9608317

    Article  ADS  Google Scholar 

  73. J. Ellis, D.S. Hwang, J. High Energy Phys. 1209, 071 (2012). arXiv:1202.6660 [hep-ph]

    Article  ADS  Google Scholar 

  74. J. Alwall et al., MadGraph 5: going beyond. J. High Energy Phys. 1106, 128 (2011). arXiv:1106.0522 [hep-ph]

    Article  ADS  Google Scholar 

  75. T. Sjostrand, S. Mrenna, P.Z. Skands, PYTHIA 6.4 Physics and Manual. J. High Energy Phys. 0605, 026 (2006). hep-ph/0603175

    Article  ADS  Google Scholar 

  76. S. Ovyn, X. Rouby, V. Lemaitre, Delphes, a framework for fast simulation of a generic collider experiment. arXiv:0903.2225 [hep-ph]

  77. A. Alves. arXiv:1209.1037 [hep-ph]

  78. R. Cousins, J. Mumford, J. Tucker, V. Valuev, J. High Energy Phys. 11, 046 (2005)

    Article  ADS  Google Scholar 

  79. N.D. Christensen, C. Duhr, FeynRules—Feynman rules made easy. Comput. Phys. Commun. 180, 1614 (2009). arXiv:0806.4194 [hep-ph]

    Article  ADS  Google Scholar 

  80. C. Degrande, C. Duhr, B. Fuks, D. Grellscheid, O. Mattelaer, T. Reiter, UFO—the universal FeynRules output. Comput. Phys. Commun. 183, 1201 (2012). arXiv:1108.2040 [hep-ph]

    Article  ADS  Google Scholar 

  81. F. Caravaglios, M.L. Mangano, M. Moretti, R. Pittau, Nucl. Phys. B 539, 215 (1999). hep-ph/9807570

    Article  ADS  Google Scholar 

  82. M.L. Mangano, M. Moretti, R. Pittau, Nucl. Phys. B 632, 343 (2002). hep-ph/0108069

    Article  ADS  Google Scholar 

  83. M.L. Mangano, M. Moretti, F. Piccinini, R. Pittau, A.D. Polosa, J. High Energy Phys. 0307, 001 (2003). hep-ph/0206293

    Article  ADS  Google Scholar 

  84. ATLAS Collaboration, https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/CONFNOTES/ATLAS-CONF-2012-127/

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Acknowledgements

We thank Oliver Buchmüller, Ben Gripaios, Rakhi Mahbubani, Eduard Massó, and Pierre Savard for valuable discussions. The work of J.E. was supported partly by the London Centre for Terauniverse Studies (LCTS), using funding from the European Research Council via the Advanced Investigator Grant 267352. The work of D.S.H. was supported partly by the Korea Foundation for International Cooperation of Science & Technology (KICOS) and the Basic Science Research Programme of the National Research Foundation of Korea (2012-0002959). The work of T.Y. was supported by a Graduate Teaching Assistantship from King’s College London. J.E., D.S.H. and V.S. thank CERN for kind hospitality, and T.Y. thanks Prof. T. Kobayashi and the Bilateral International Exchange Program of Kyoto University for kind hospitality.

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Authors and Affiliations

  1. Theoretical Particle Physics and Cosmology Group, Physics Department, King’s College London, London, WC2R 2LS, UK

    John Ellis & Tevong You

  2. TH Division, Physics Department, CERN, 1211, Geneva 23, Switzerland

    John Ellis & Verónica Sanz

  3. Department of Physics and Astronomy, York University, Toronto, ON, Canada, M3J 1P3

    Ricky Fok & Verónica Sanz

  4. Department of Physics, Sejong University, Seoul, 143–747, South Korea

    Dae Sung Hwang

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  1. John Ellis
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Correspondence to Verónica Sanz.

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Ellis, J., Fok, R., Hwang, D.S. et al. Distinguishing ‘Higgs’ spin hypotheses using γγ and WW ∗ decays. Eur. Phys. J. C 73, 2488 (2013). https://doi.org/10.1140/epjc/s10052-013-2488-5

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