2,055 research outputs found

    Explanation of the ATLAS Z-peaked excess by squark pair production in the NMSSM

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    The ATLAS collaboration recently reported a 3Οƒ3\sigma excess in the leptonic-Z+jets+ETmissZ+jets+E_{T}^{miss} channel. We intend to interpret this excess by squark pair production in the Next-to-Minimal Supersymmetric Standard Model (NMSSM). The decay chain we employ is q~β†’qΟ‡~20β†’qΟ‡~10Z\tilde{q} \to q \tilde{\chi}_2^0 \to q \tilde{\chi}_1^0 Z, where Ο‡~10\tilde{\chi}_1^0 and Ο‡~20\tilde{\chi}_2^0 denote the lightest and the next-to-lightest neutralinos with singlino and bino as their dominant components respectively. Our simulations indicate that after considering the constraints from the ATLAS searches for jets+ETmissjets + E_{T}^{miss} signal the central value of the excess can be obtained for mq~≲1.2TeVm_{\tilde{q}} \lesssim 1.2 {\rm TeV}, and if the constraint from the CMS on-ZZ search is further considered, more than 10 signal events are still attainable for mq~≲750GeVm_{\tilde{q}} \lesssim 750 {\rm GeV}. Compared with the interpretation by gluino pair production, the squark explanation allows for a significantly wider range of mq~m_{\tilde{q}} as well as a less compressed SUSY mass spectrum. We also show that the squark explanation will be readily tested at the initial stage of the 14 TeV LHC.Comment: 19 pages, 4 figure

    Explanation of the ATLAS Z-peaked excess in the NMSSM

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    Recently the ATLAS collaboration reported a 3Οƒ3\sigma excess in the leptonic-Z+jets+ETmissZ+jets+E_{T}^{miss} channel. This may be interpreted in the Next-to-Minimal Supersymmetric Standard Model (NMSSM) by gluino pair production with the decay chain g~β†’qqΛ‰Ο‡~20β†’qqΛ‰ZΟ‡~10\tilde{g} \to q \bar{q} \tilde{\chi}_2^0 \to q \bar{q} Z \tilde{\chi}_1^0, where Ο‡~10\tilde{\chi}_1^0 and Ο‡~20\tilde{\chi}_2^0 denote the lightest and the next-to-lightest neutralinos with singlino and bino as their dominant components respectively. After exploring the relevant parameter space of the NMSSM by considering the constraints from the ATLAS searches for jets+ETmissjets + E_{T}^{miss} signals, we conclude that the NMSSM is able to explain the excess at 1Οƒ1 \sigma level with the number of the signal events reaching its measured central value in optimal cases, and the best explanation comes from a compressed spectrum such as mg~≃650GeVm_{\tilde{g}} \simeq 650 {\rm GeV}, mΟ‡~20≃565GeVm_{\tilde{\chi}_2^0} \simeq 565 {\rm GeV} and mΟ‡~10≃465GeVm_{\tilde{\chi}_1^0} \simeq 465 {\rm GeV}. We also check the consistency of the ATLAS results with the null result of the CMS on-ZZ search. We find that under the CMS limits at 95%95\% C.L., the event number of the ATLAS on-ZZ signal can still reach 11 in our scenario, which is about 1.2Οƒ1.2 \sigma away from the measured central value.Comment: 18 pages, 2 figure

    PHYS 111-011: Physics I

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