Observation of a diffractive contribution to dijet production in proton-proton collisions ats=7  TeV

Abstract

The cross section for dijet production in proton-proton collisions at ffiffi ffi s p ¼ 7 TeV is presented as a function of, a variable that approximates the fractional momentum loss of the scattered proton in singlediffractive events. The analysis is based on an integrated luminosity of 2:7 nb À1 collected with the CMS detector at the LHC at low instantaneous luminosities, and uses events with jet transverse momentum of at least 20 GeV. The dijet cross section results are compared to the predictions of diffractive and nondiffractive models. The low-data show a significant contribution from diffractive dijet production, observed for the first time at the LHC. The associated rapidity gap survival probability is estimated.

Inelastic cross section and survival probabilities at the LHC in minijet models

“…5 the values taken byS 2 total for GRV and MSTW densities, in comparison with GLM and KMR estimated ranges. We also show comparison with the NLO CMS estimate [21]. Since our present proposal is obtained by resummation of soft gluons to all orders, the comparison with NLO result is the appropriate one.…”

“…A comparison is also shown with the LO result by the CMS collaboration [21] for the survival probability in the measurement of the diffractive contribution to dijet production at √ s = 7 T eV . CMS gives an estimate of S 2 = 0.12 ± 0.05 at LO, and a lower value of S 2 = 0.08 ± 0.04 at NLO.…”

Hard diffraction with dynamic gap survival

“…At the LHC, diffraction has been studied both by ATLAS [39][40][41] and CMS [42][43][44]. One key observation there is that the Pythia default P flux shape does not describe the rapidity gap distribution so well, suggesting that a new parametrization may be needed.…”

“…In other respects the model seems to do a reasonable job. For hard diffraction we will compare to the latest ATLAS study, [41], and a similar CMS study, [43].…”

Diffractive dijet photoproduction in ep collisions with a leading proton at HERA.

“…This effect is usually explained as a consequence of additional partonic interactions between both hadrons which destroy the diffractive event signaturethe rapidity gap [3]. Similar effect was recently observed at LHC by CMS collaboration [4].…”