Abstract
Results are presented from a search for particle dark matter (DM), extra dimensions, and unparticles using events containing a jet and an imbalance in transverse momentum. The data were collected by the CMS detector in proton–proton collisions at the LHC and correspond to an integrated luminosity of 19.7,text {fb}^text {-1}at a centre-of-mass energy of 8,{mathrm{TeV}},. The number of observed events is found to be consistent with the standard model prediction. Limits are placed on the DM-nucleon scattering cross section as a function of the DM particle mass for spin-dependent and spin-independent interactions. Limits are also placed on the scale parameter M_mathrm {D} in the Arkani-Hamed, Dimopoulos, and Dvali (ADD) model of large extra dimensions, and on the unparticle model parameter {{Lambda _mathrm{U}}} . The constraints on ADD models and unparticles are the most stringent limits in this channel and those on the DM-nucleon scattering cross section are an improvement over previous collider results.
Highlights
This paper describes a search for new physics using the signature of a hadronic jet and an imbalance in transverse energy resulting from undetected particles
A search for particle dark matter, large extra dimensions, and unparticle production has been performed in the monojet√channel using a data sample of proton–proton collisions at s = 8 TeV corresponding to an integrated luminosity of 19.7 fb−1
The dominant backgrounds to this topology are from Z(νν) + jets and W( ν) + jets events, and are estimated from data samples of Z(μμ) and W(μν) events, respectively
Summary
This paper describes a search for new physics using the signature of a hadronic jet and an imbalance in transverse energy resulting from undetected particles. We use the term “monojet” to describe events with this topology Such events can be produced in new physics scenarios, including particle dark matter (DM) production, large extra dimensions, and unparticles. Since WIMPs are weakly interacting and neutral, they are not expected to produce any discernible signal in the LHC detectors Like neutrinos, they remain undetected and their presence in an event must be inferred from an imbalance of the total momentum of all reconstructed particles in the plane transverse to the beam axis. In the low-energy limit, with scale dimension du, events appear to correspond to the production of a non-integer number du of invisible particles Assuming these are sufficiently long-lived to decay outside of the detector, they are undetected and so give rise to ETmiss.
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