Prospects for searches for long-lived particles after the LHCb detector upgrades

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Abstract

The LHCb detector is a single-arm forward spectrometer covering the pseudorapidity range $2 < \eta < 5$, initially designed for the study of particles containing $b$ or $c$ quarks. As such, it is naturally suited for the search of beyond SM long-lived particles in a range of mass and lifetime not too dissimilar to heavy-flavour hadrons, as it has been demonstrated in several publications. Prospects for these searches in regard of future LHC upgrades, where challenging conditions are foreseen, are presented in this conference note with the goal to serve as an input for the HL-LHC and HE-LHC Yellow Report.

Figures and captions

 Projected sensitivities of the search for RPV supersymmetric neutralinos decaying semileptonically [6] and produced through a Higgs boson exotic decay. The results are extrapolated from Run 1 results (top left), for luminosities of 23 $\text{ fb} ^{-1}$ (top right), 50 $\text{ fb} ^{-1}$ (bottom left) and 300 $\text{ fb} ^{-1}$ (bottom right). The results are presented in terms of the excluded parameter space of the neutralinos for different upper limits at 95% C.L. on the branching fractions of the Higgs boson decay. LLP_co[..].pdf [188 KiB] HiDef png [208 KiB] Thumbnail [178 KiB] *.C file LLP_co[..].pdf [189 KiB] HiDef png [395 KiB] Thumbnail [323 KiB] *.C file LLP_co[..].pdf [193 KiB] HiDef png [373 KiB] Thumbnail [296 KiB] *.C file LLP_co[..].pdf [201 KiB] HiDef png [443 KiB] Thumbnail [323 KiB] *.C file LLP_co[..].pdf [76 KiB] HiDef png [324 KiB] Thumbnail [271 KiB] *.C file Comparison of projected sensitivities in the search for RPV supersymmetric neutralinos decaying semileptonically [6] and produced through a Higgs boson exotic decay. The sensitivities are extrapolated from Run 1 results, and the figure compares parameter regions where the branching fraction of the Higgs boson decay to a $\tilde{\chi}^{0}_{1} \tilde{\chi}^{0}_{1}$ pair is constrained to be smaller than 2% (left) and 0.5% (right) at 95% CL. LLP_co[..].pdf [129 KiB] HiDef png [183 KiB] Thumbnail [153 KiB] *.C file LLP_co[..].pdf [130 KiB] HiDef png [271 KiB] Thumbnail [221 KiB] *.C file LLP_co[..].pdf [63 KiB] HiDef png [123 KiB] Thumbnail [123 KiB] *.C file Projected sensitivities of the search for HV pions decaying hadronically [5] and produced through a Higgs boson exotic decay. The results are extrapolated from Run 1 results (top left), for luminosities of 23 $\text{ fb} ^{-1}$ (top right), 50 $\text{ fb} ^{-1}$ (bottom left) and 300 $\text{ fb} ^{-1}$ (bottom right). The results are presented in terms of the excluded parameter space of the HV pions for different upper limits at 95% C.L. on the branching fractions of the Higgs boson decay. LLP_co[..].pdf [189 KiB] HiDef png [186 KiB] Thumbnail [151 KiB] *.C file LLP_co[..].pdf [190 KiB] HiDef png [405 KiB] Thumbnail [289 KiB] *.C file LLP_co[..].pdf [192 KiB] HiDef png [423 KiB] Thumbnail [305 KiB] *.C file LLP_co[..].pdf [192 KiB] HiDef png [421 KiB] Thumbnail [316 KiB] *.C file LLP_co[..].pdf [64 KiB] HiDef png [257 KiB] Thumbnail [262 KiB] *.C file Comparison of projected sensitivities in the search for HV pions decaying hadronically [5] and produced through a Higgs boson exotic decay. The sensitivities are extrapolated from Run 1 results, and the figure compares parameter regions where the branching fraction of the Higgs boson decay to a $\pi_v\pi_v$ pair is constrained to be smaller than 20% (left) and 2% (right) at 95% CL. LLP_co[..].pdf [131 KiB] HiDef png [316 KiB] Thumbnail [224 KiB] *.C file LLP_co[..].pdf [130 KiB] HiDef png [320 KiB] Thumbnail [231 KiB] *.C file LLP_co[..].pdf [63 KiB] HiDef png [96 KiB] Thumbnail [109 KiB] *.C file Animated gif made out of all figures. CONF-2018-006.gif Thumbnail

Tables and captions

 Assumptions for the integrated luminosity used in this document. Table_1.pdf [27 KiB] HiDef png [32 KiB] Thumbnail [17 KiB] tex code Examples of the acceptance and total efficiencies assumed to detect a $\tilde{\chi}^{0}_{1}$ decaying semileptonically at a $pp$ collision energy of $\sqrt{s}=13$ TeV at the LHCb detector. Background yields at an integrated luminosity of 1.7 $\text{ fb} ^{-1}$ are also presented. Differences in these yields are due to the effect of a multivariate classifier which is trained differently for each mass-lifetime case. Table_2.pdf [66 KiB] HiDef png [57 KiB] Thumbnail [28 KiB] tex code Background yields assumed for the HV pion analysis at an integrated luminosity of 23 $\text{ fb} ^{-1}$ . The yields are divided in bins of $R_{xy}=\sqrt{x^2+y^2}$, where $x,y$ are the coordinates of the $\pi_v$ particle decay vertex position. Values are extrapolated from Ref. [5]. [Error creating the table] Examples of the acceptance and total efficiencies assumed to detect a $\pi_v$ particle decaying to a pair of jets at a $pp$ collision energy $\sqrt{s}=14$ TeV at the LHCb detector. The main inefficiencies arise from the requirements to have $\pi_v$ particle in the VELO and to have the decay products in the LHCb acceptance and from the reconstruction of the secondary vertex. More details can be found in Ref. [5]. Table_4.pdf [55 KiB] HiDef png [63 KiB] Thumbnail [33 KiB] tex code

Created on 02 November 2019.