Constraining qqtt operators from four-top production: a case for enhanced EFT sensitivity

  • Recently, experimental collaborations have reported O(10) upper limits on the signal strength of four-top production at the LHC. Surprisingly, we find that the constraining power of four-top production on the qqtt type of operators is already competitive with the measurements of top-pair production, even though the precision level of the latter is more than two orders of magnitude better. This is explained by the enhanced sensitivity of the four-top cross section to qqtt operators, due to multiple insertion of operators in the squared amplitude, and to the large threshold energy of four-top production. We point out that even though the dominant contribution beyond the standard model comes from the O(C44/Λ8) terms, the effective field theory expansion remains valid for a wide range of underlying theories. Considering the possible improvements of this measurement with higher integrated luminosity, we believe that this process will become even more crucial for probing and testing the standard model deviations in the top-quark sector, and will eventually provide valuable information about the top-quark properties, leading to significant improvements in precision top physics.
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Cen Zhang. Constraining qqtt operators from four-top production: a case for enhanced EFT sensitivity[J]. Chinese Physics C, 2018, 42(2): 023104. doi: 10.1088/1674-1137/42/2/023104
Cen Zhang. Constraining qqtt operators from four-top production: a case for enhanced EFT sensitivity[J]. Chinese Physics C, 2018, 42(2): 023104.  doi: 10.1088/1674-1137/42/2/023104 shu
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Received: 2017-08-22
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    Supported by the 100-talent project of Chinese Academy of Sciences

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Constraining qqtt operators from four-top production: a case for enhanced EFT sensitivity

    Corresponding author: Cen Zhang,
  • 1. Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
Fund Project:  Supported by the 100-talent project of Chinese Academy of Sciences

Abstract: Recently, experimental collaborations have reported O(10) upper limits on the signal strength of four-top production at the LHC. Surprisingly, we find that the constraining power of four-top production on the qqtt type of operators is already competitive with the measurements of top-pair production, even though the precision level of the latter is more than two orders of magnitude better. This is explained by the enhanced sensitivity of the four-top cross section to qqtt operators, due to multiple insertion of operators in the squared amplitude, and to the large threshold energy of four-top production. We point out that even though the dominant contribution beyond the standard model comes from the O(C44/Λ8) terms, the effective field theory expansion remains valid for a wide range of underlying theories. Considering the possible improvements of this measurement with higher integrated luminosity, we believe that this process will become even more crucial for probing and testing the standard model deviations in the top-quark sector, and will eventually provide valuable information about the top-quark properties, leading to significant improvements in precision top physics.

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