Abstract
AbstractA search for new phenomena in events with a high-energy jet and large missing transverse momentum is performed using data from proton-proton collisions at$ \sqrt{s}=7 $TeV with the ATLAS experiment at the Large Hadron Collider. Four kinematic regions are explored using a dataset corresponding to an integrated luminosity of 4.7 fb−1. No excess of events beyond expectations from Standard Model processes is observed, and limits are set on large extra dimensions and the pair production of dark matter particles.
Highlights
Background estimationA number of SM processes can pass the monojet kinematic selection criteria described above
In order to measure this background from data, a sample is selected by applying all signal-region selection criteria except for the jet vetoes: A) either a second jet with |∆φ(pmTiss, pjTet2)| < 0.5 is required, B) or the third-jet veto is reversed by requiring three jets, Njet = 3, and missing transverse momentum to be aligned with the third jet: |∆φ(pmTiss, pjTet3)| < 0.5 and |∆φ(pmTiss, pjTet2)| > 0.5
To facilitate comparisons with other experiments both 90% and the more conventional 95% confidence level (CL) upper limits are produced. These limits are on the visible cross section defined as cross section times acceptance and efficiency (σ × A × ǫ) and they are based on the modified frequentist CLs prescription [67]
Summary
The ATLAS detector [34, 35] at the LHC covers the pseudorapidity range of |η| < 4.9 and all of φ. Processes that dominate the background are Z- or W - boson production in association with jets, which are simulated with ALPGEN [38] using the parton distribution function (PDF) set CTEQ6L1 [39]. For graviton production in the ADD model, a low-energy effective field theory [26] with energy scale MD is used to calculate the signal cross section considering the contribution of different graviton mass modes. The samples are produced with an ADD implementation as a user model of PYTHIA, which is used for parton showering and hadronisation. WIMP pair production plus one and two additional partons from ISR/FSR is simulated requiring at least one parton with a minimum transverse momentum of 80 GeV. The MLM prescription is used for matching the matrix-element calculations of MADGRAPH5 to the parton shower evolution of PYTHIA. MC events are re-weighted to reproduce the distribution of the number of collisions per bunch crossing observed in the data
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
