Enhancing sensitivities to long-lived particles with high granularity calorimeters at the LHC
A bstract The search for long-lived particles (LLP) is an exciting physics opportunity in the upcoming runs of the Large Hadron Collider. In this paper, we focus on a new search strategy of using the High Granularity Calorimeter (HGCAL), part of the upgrade of the CMS detector, in such searches. In particular, we demonstrate that the high granularity of the calorimeter allows us to see “shower tracks” in the calorimeter, and can play a crucial role in identifying the signal and suppressing the background. We study the potential reach of the HGCAL using a signal model in which the Standard Model Higgs boson decays into a pair of LLPs, h → XX . After carefully estimating the Standard Model QCD and the misreconstructed fake-track backgrounds, we give the projected reach for both an existing vector boson fusion trigger and a novel displaced-track-based trigger. Our results show that the best reach for the Higgs decay branching ratio, BR( h → XX ), in the vector boson fusion channel is about $$\mathcal{O}$$ O (10 − 4 ) with lifetime cτ X ∼ 0 . 1–1 meters, while for the gluon gluon fusion channel it is about $$\mathcal{O}$$ O more »
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Award ID(s):
Publication Date:
NSF-PAR ID:
10273115
Journal Name:
Journal of High Energy Physics
Volume:
2020
Issue:
11
ISSN:
1029-8479
1. A bstract A search for a light pseudoscalar Higgs boson (a) decaying from the 125 GeV (or a heavier) scalar Higgs boson (H) is performed using the 2016 LHC proton-proton collision data at $$\sqrt{s}$$ s = 13 TeV, corresponding to an integrated luminosity of 35 . 9 fb − 1 , collected by the CMS experiment. The analysis considers gluon fusion and vector boson fusion production of the H, followed by the decay H → aa → μμττ , and considers pseudoscalar masses in the range 3 . 6 < m a < 21 GeV. Because of themore »
2. Abstract A search is performed for massive long-lived particles (LLPs) decaying semileptonically into a muon and two quarks. Two kinds of LLP production processes were considered. In the first, a Higgs-like boson with mass from 30 to 200 $$\text {\,GeV\!/}c^2$$ \,GeV\!/ c 2 is produced by gluon fusion and decays into two LLPs. The analysis covers LLP mass values from 10 $$\text {\,GeV\!/}c^2$$ \,GeV\!/ c 2 up to about one half the Higgs-like boson mass. The second LLP production mode is directly from quark interactions, with LLP masses from 10 to 90 $$\text {\,GeV\!/}c^2$$ \,GeV\!/ c 2 . The LLPmore »
3. A bstract A novel search for exotic decays of the Higgs boson into pairs of long-lived neutral particles, each decaying into a bottom quark pair, is performed using 139 fb − 1 of $$\sqrt{s}$$ s = 13 TeV proton-proton collision data collected with the ATLAS detector at the LHC. Events consistent with the production of a Higgs boson in association with a leptonically decaying Z boson are analysed. Long-lived particle (LLP) decays are reconstructed from inner-detector tracks as displaced vertices with high mass and track multiplicity relative to Standard Model processes. The analysis selection requires the presence ofmore »
5. A bstract A search for standard model Higgs bosons (H) produced with transverse momentum ( p T ) greater than 450 GeV and decaying to bottom quark-antiquark pairs ( $$\mathrm{b}\overline{\mathrm{b}}$$ b b ¯ ) is performed using proton-proton collision data collected by the CMS experiment at the LHC at $$\sqrt{s}$$ s = 13 TeV. The data sample corresponds to an integrated luminosity of 137 fb − 1 . The search is inclusive in the Higgs boson production mode. Highly Lorentz-boosted Higgs bosons decaying to $$\mathrm{b}\overline{\mathrm{b}}$$ b b ¯ are reconstructed as single large-radius jets,more »