Resonant Higgs pair production as a probe of stop at the LHC

Journal of High Energy Physics, Sep 2017

Abstract Searching for top squark (stop) is a crucial task of the LHC. When the flavor conserving two body decays of the stop are kinematically forbidden, the stops produced near the threshold will live long enough to form bound states which subsequently decay through annihilation into the Standard Model (SM) final states. In the region of stop mixing angle \( {\theta}_{\tilde{t}}\to 0 \) or π/2, we note that the LHC-13 TeV diphoton resonance data can give a strong bound on the spin-0 stoponium (\( {\eta}_{\tilde{t}} \)) and exclude the constituent stop mass \( {m}_{\tilde{t}} \) up to about 290 GeV. While in the large stop mixing region, the stoponium will dominantly decay to the Higgs pair. By analyzing the process \( pp\to {\eta}_{\tilde{t}}\to h\left(\to b\overline{b}\right)h\left(\to {\tau}^{+}{\tau}^{-}\right) \), we find that a large portion of the parameter space on the \( {m}_{{\tilde{t}}_1}-{\theta}_{\tilde{t}} \) plane can be probed at 2σ- significance level at the LHC with the luminosity ℒ = 3000 fb−1.

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Resonant Higgs pair production as a probe of stop at the LHC

Received: June Resonant Higgs pair production as a probe of stop at Guang Hua Duan 0 1 2 3 6 8 9 10 Lei Wu 0 1 3 5 7 8 9 10 Rui Zheng 0 1 3 4 8 9 10 0 Davis , CA, 95616 U.S.A 1 Beijing , 100049 China 2 School of Physical Sciences, University of Chinese Academy of Sciences 3 Beijing , 100190 China 4 Department of Physics, University of California , USA 5 ARC Centre of Excellence for Particle Physics at the Terascale, School of Physics 6 Institute of Theoretical Physics, Chinese Academy of Sciences 7 Department of Physics and Institute of Theoretical Physics, Nanjing Normal University 8 nal states. In the region of stop 9 The University of Sydney , New South Wales, 2006 Australia 10 Nanjing , Jiangsu, 210023 China Searching for top squark (stop) is a crucial task of the LHC. When the avor conserving two body decays of the stop are kinematically forbidden, the stops produced near the threshold will live long enough to form bound states which subsequently decay through annihilation into the Standard Model (SM) mixing angle t~ ! 0 or =2, we note that the LHC-13 TeV diphoton resonance data can give a strong bound on the spin-0 stoponium ( t~) and exclude the constituent stop mass m~ t up to about 290 GeV. While in the large stop mixing region, the stoponium will dominantly signi cance level at the LHC with the luminosity L = 3000 fb 1. decay to the Higgs pair. By analyzing the process pp ! t~ ! h(! bb)h(! that a large portion of the parameter space on the mt~1 { t~ plane can be probed at 2 Supersymmetry Phenomenology - ArXiv ePrint: 1706.07562 1 Introduction 2 Diphoton resonance constraint on the stoponium 3 Di-Higgs decay of stoponium with bb + nal states at the LHC 4 Conclusions 1 Introduction mass splitting which leads to di erent decay modes. For instance, when mt~1 > mt + m~01 and t~1 mainly decays to t ~01, the top quark from stop decay can be quite energetic and a stop mass up to 940 GeV for a massless lightest neutralino has been excluded by the very recent LHC run-2 data [17]. When the avor-conserving two body decays channels the light stop would be the three-body decay t~1 ! W +b ~01, the two-body like t~1 ! t ~01 and t~1 ! b ~1+ are kinematically forbidden, the primary decay channels of avor-changing decay t~1 ! c ~01 or the four-body decay t~1 ! bf 0f ~01 [18{25]. The current null results of LHC searches for these decay channels have correspondingly excluded the stop mass up to 500 GeV, 310 GeV and 370 GeV for certain mass splitting between the stop and the LSP [17]. It should be mentioned that such a light stop usually has very small decay width [26] compared to the typical binding energy of t~1t~1 bound state (stoponium). In this case, two stops produced near-threshold could live long enough to form a stoponium due to the Coulomb-like attraction via the QCD interaction. In contrast to the existing direct stop pair searches, stoponium if formed, will resonantly decay to a pair of the SM particles and can be independent of the assumptions of the LSP mass and the branching ratios of the { 1 { stop. Therefore, it is expected that the search of stoponium can provide a complementary probe to the direct stop pair production at the LHC. The phenomenologies of the stoponium have been studied at colliders [26{34]. In particular, the diphoton channel was studied and found to be a promising way to observe stoponium at the LHC in refs. [26{28]. The diboson decay of stoponium with W W and ZZ nal states were also examined in [32, 33]. In [35], the authors investigated the di-Higgs decay of stoponium with bb nal states and found it to be a viable channel at the LHC. But the loop induced diphoton decay of the Higgs boson can be sizably a ected by other sparticles, such as the light stau in the MSSM [36]. high mass resonances at 13 TeV LHC. Then we explore the potential of probing the stop in Higgs pair production with bb + nal states at high-luminosity LHC (HL-LHC). As a comparison with bb channel, although the bb + channel su ers from relatively complicated backgrounds, it has a larger branching ratio. Besides, it is expected that the reconstruction e ciency of can reach 80% with the likelihood taggers in the future LHC experiment [ 37, 38 ]. This will make bb + channel become another promising way of discovering, or con rming the stoponium at the LHC. The paper is organized as follows. In section 2, we introduce productions and decays of the stoponium and display the limits on stoponium mass from the LHC-13 TeV data. In section 3, we investigate the observability of the di-Higgs decay of the stoponium with bb nal states at the LHC. Finally, we draw our conclusions in section 4. In this paper, we rst confront the stoponium with the recent data of searching for mtXty 1 A mt2~L = m2Q~3L + mt2 + m2Z sin2 W cos 2 ; mt2~R = m2U~3R Xt = At cot ; 2 3 + mt2 + m2Z sin2 W cos 2 ; 1 2 + tR 2 3 (2.1) (2.2) (2.3) (2.4) (2.5) where mQ~3L and mU~3R denote the soft-breaking mass parameters of the th (...truncated)


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Guang Hua Duan, Lei Wu, Rui Zheng. Resonant Higgs pair production as a probe of stop at the LHC, Journal of High Energy Physics, 2017, pp. 37, Volume 2017, Issue 9, DOI: 10.1007/JHEP09(2017)037