Search for bottom-squark pair production with the ATLAS detector in final states containing Higgs bosons, b-jets and missing transverse momentum

Abstract

The result of a search for the pair production of the lightest supersymmetric partner of the bottom quark (b 1 ) using 139 fb −1 of proton-proton data collected at √ s = 13 TeV by the ATLAS detector is reported. In the supersymmetric scenarios considered both of the bottom-squarks decay into a b-quark and the second-lightest neutralino,b 1 → b +χ 0 2 . Eachχ 0 2 is assumed to subsequently decay with 100% branching ratio into a Higgs boson (h) like the one in the Standard Model and the lightest neutralino:χ 0 2 → h +χ 0 1 . Theχ 0 1 is assumed to be the lightest supersymmetric particle (LSP) and is stable. Two signal mass configurations are targeted: the first has a constant LSP mass of 60 GeV; and the second has a constant mass difference between theχ 0 2 andχ 0 1 of 130 GeV. The final states considered contain no charged leptons, three or more b-jets, and large missing transverse momentum. No significant excess of events over the Standard Model background expectation is observed in any of the signal regions considered. Limits at the 95% confidence level are placed in the supersymmetric models considered, and bottom-squarks with mass up to 1.5 TeV are excluded.

Vector boson fusion at multi-TeV muon colliders

“…This leads to the existence of a new degree of freedom for each SM one that is mass-degenerate but with opposite spin-statistics, and that order-by-order contribute oppositely to quantum corrections of the Higgs's mass. The lack of experimental evidence for superpartners [124][125][126][127][128][129][130][131][132][133], however, suggests that if SUSY is realized at a certain scale it is broken at the EW scale.…”

“…The mass eigenstates, denoted byχ 0 k andχ ± k , are given as linear combinations of the fields {B,W 0 ,H 0 d ,H 0 u } and {W + ,H + u ,W − ,H − d }, respectively. Despite extensive searches for these states [121][122][123][124][125], including direct searches at the LHC [126][127][128][129][130][131][132][133], evidence for the MSSM at the weak scale has yet be established. If the MSSM, or any variation of SUSY, is realized at the EW-or TeV-scale, then a multi-TeV muon collider could be an optimal machine to discover missing superparticles or study the spectrum properties.…”

The DNNLikelihood: enhancing likelihood distribution with Deep Learning

“…As a final remark, we stress the fact that the proposed approach supports and complements the remarkable step taken by the ATLAS collaboration in publishing full experi-mental likelihoods [12,14,15]. On one hand, the DNNLikelihood framework can be seen as a way to export a Hist-Factory likelihood to a software environment that does not meet the needed dependencies, or as an alternative option for experimental collaborations that do not use HistFactory.…”

“…Notice that increasing the batch size when enlarging the training set, also allowed us to keep the initial learning rate (LR)) fixed [63]. 12 Similar results could be obtained by keeping a fixed batch size of 512 and reducing the starting learning rate when enlarging the training set.…”

“…Recently, the ATLAS collaboration has taken a major step forward, releasing the full experimental LF of an analysis [12] on HEPData [13] through the HistFactory framework [14], with the format presented in Ref. [15].…”