Study of the Discovery Reach in Searches for Supersymmetry at CMS with 3000 fb^-1

Link to the document in CDS

Abstract:

It is planned that the Large Hadron Collider will deliver an integrated luminosity of up to 3000 fb^-1 for each experiment, requiring an upgrade of the detector which would otherwise not survive the radiation damage. The reach of several representative searches for supersymmetry with the upgraded detector is studied for this scenario, where a very high instantaneous luminosity will lead to a large number of pileup events in each bunch crossing. The studies comprise the production of gluinos decaying to third generation squarks as well as to light squarks, and the direct production of neutralino-chargino pairs decaying to final states including a Z and a W boson. Depending on the SUSY particles, we can improve the discovery reach by about 300 to 400 GeV increasing the luminosity from 300 to 3000 fb^-1. In addition, the possible gain from extending the tracker up to a pseudorapidity of four is studied for vector boson fusion processes.

Contents:

Search for SUSY in final states with jets and missing hadronic energy

Figure/Table	Links	Description
	pdf, png	Figure 1: Diagram of gluino-gluino production in which each gluino decays to two jets and the LSP.
	(a) pdf, png, (b) pdf, png, (c) pdf, png, (d) pdf, png	Figure 2: HT (left) and MHT (right) distributions for both signal and background for the 14 TeV, 3000 fb-1 scenario. Both plots on the top are done with the Phase I detector without pileup interactions, while the bottom plots are done for the same detector configuration, but with 140 pileup interactions. The signal distribution is for the gluino mass and LSP mass of 2100 and 100 GeV, respectively.
	pdf, png	Figure 3: The projected 5σ discovery reaches for pair production of gluinos decaying to four quarks and two LSPs. The blue curve is for 300 fb-1 data with the Phase I detector. The red curve is for 3000 fb-1 with the Phase II Conf3 detector. The result is not very sensitive to different detector and pileup scenarios, therefore only the result for one configuration is shown.

Search for gluinos decaying to top quarks and neutralinos in the single lepton final state

Figure/Table	Links	Description
	pdf, png	Figure 4: Example of the gluino-induced stop quark production mechanism.
	pdf, png	Figure 5: The projected 5σ discovery reach for a simplified model describing gluino production, with each gluino decaying to a t-tbar pair and an LSP, for 300 fb-1 (dashed curves) and 3000 fb-1 (solid curves). The discovery reach is shown for = 0 (black) and = 140 (magenda).
	pdf, png	Table 1: Event yields for the combined electron and muon channels, as expected from simulation for Njet ≥ 6 and Nb ≥ 4 for the Phase II Conf3 detector configuration. For the sample names, V is used to denote W bosons, Z bosons, and photons. The column ”RCS” lists the ratio of yields in the signal (Dφ(W,l) > 1) region to those in the control (Dφ(W,l) < 1) region. The yields for an exemplary signal point are shown for comparison, with the gluino and LSP masses (in GeV) listed in brackets. The uncertainties are statistical only.

EWKino search with final states including three leptons and missing transverse energy

Figure/Table	Links	Description
	pdf, png	Figure 6: Feynman diagram for direct chargino-neutralino production. The chargino decays via a W boson into the LSP, and the neutralino decays via a Z boson into the LSP. We concentrate on scenarios where both leptons decay leptonically.
	(a) pdf, png, (b) pdf, png, (c) pdf, png, (d) pdf, png	Figure 7: The MET (left) and the MT distribution (right) for event with 3 leptons and a b-veto for the Phase I detector with zero pileup (top) and 140 pileup events (bottom). In addition to the SM predictions some possible SUSY benchmark scenarios are included.
	(a) pdf, png, (b) pdf, png,	Figure 8: 5σ discovery reach for the simplified model describing the direct production of charginos and neutralinos, that decay to 100% via a W and Z boson for 3000 fb-1 (top), for a mean of 140 pileup events with the upgraded Phase II detector (solid magenta line), and also for zero pileup with the Phase I detector (black solid line). Results for 300 fb-1 with zero pileup are displayed as dashed lines. A χ20 → Zχ10 branching ratio of 100% may be not realistic. To illustrate the migration of the discovery reach due to a smaller branching ratio, we show here for illustration the result for a branching ratio of 50% as well (bottom).
	pdf, png	Table 2: Standard model background predictions for the different scenarios at 3000 fb-1.

Dark matter search in vector boson fusion processes

Figure/Table	Links	Description
	pdf, png	Figure 9: Diagram for χ10χ10 production via VBF process.
	pdf, png	Figure 10: The lepton η distribution in W + jets and t-tbar events after the loose VBF selection used in [Ref].
	(a) pdf, png, (b) pdf, png,	Figure 11: Muon (left) and electron (right) selection efficiencies as a function of η. The efficiencies are determined for muons and electrons with pT > 5 GeV in W(lν) + jets events.
	pdf, png	Figure 12: Pseudorapidity distributions for jets with pT > 30 GeV for various pileup and detector configurations in W(lν) + jets events.
	(a) pdf, png, (b) pdf, png,	Figure 13: Comparison of MHT and Mjj distributions in W(lν) + jets samples from different detectors with different pileup scenarios. All W(lν) + jets events without any event selection are shown for MHT distributions and W(lν) + jets events with at least two jets with pT > 30 GeV are shown for Mjj distributions.