Measurement of differential cross sections for single diffractive dissociation in s $$ \sqrt{s}
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Received: November 4, 2019 Accepted: January 23, 2020 Published: February 6, 2020
The ATLAS collaboration E-mail: [email protected] Abstract: A dedicated sample of Large Hadron Collider proton-proton collision data at √ centre-of-mass energy s = 8 TeV is used to study inclusive single diffractive dissociation, pp → Xp. The intact final-state proton is reconstructed in the ATLAS ALFA forward spectrometer, while charged particles from the dissociated system X are measured in the central detector components. The fiducial range of the measurement is −4.0 < log10 ξ < −1.6 and 0.016 < |t| < 0.43 GeV2 , where ξ is the proton fractional energy loss and t is the squared four-momentum transfer. The total cross section integrated across the fiducial range is 1.59 ± 0.13 mb. Cross sections are also measured differentially as functions of ξ, t, and ∆η, a variable that characterises the rapidity gap separating the proton and the system X. The data are consistent with an exponential t dependence, dσ/dt ∝ eBt with slope parameter B = 7.65 ± 0.34 GeV−2 . Interpreted in the framework of triple Regge phenomenology, the ξ dependence leads to a pomeron intercept of α(0) = 1.07 ± 0.09. Keywords: Diffraction, Forward physics, Hadron-Hadron scattering (experiments), QCD ArXiv ePrint: 1911.00453
Open Access, Copyright CERN, for the benefit of the ATLAS Collaboration. Article funded by SCOAP3 .
https://doi.org/10.1007/JHEP02(2020)042
JHEP02(2020)042
Measurement of differential cross sections for single √ diffractive dissociation in s = 8 TeV pp collisions using the ATLAS ALFA spectrometer
Contents 1
2 Experimental conditions
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3 Monte Carlo simulation
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4 Data selection and reconstruction
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5 Kinematic variables and fiducial region
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6 Backgrounds
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7 Control distributions
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8 Unfolding
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9 Uncertainties
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10 Results
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11 Summary
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The ATLAS collaboration
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1
Introduction
In the single diffractive (SD) dissociation process in proton-proton (pp) collisions, pp → Xp (figure 1(a)), the absolute value of the squared four-momentum transfer t is usually much smaller than 1 GeV2 , such that the intact final-state proton is scattered through a very small angle of typically 10–100 µrad. The other proton dissociates to produce a multiparticle hadronic system X, whose mass MX can reach many hundreds of GeV at Large Hadron Collider (LHC) energies, whilst remaining in a regime where the fractional energy 2 /s is small. loss of the intact proton ξ = MX Measurements of the SD cross section have been made at a wide range of energies [1–4], most recently at the SPS [5, 6], the Tevatron [7, 8] and HERA [9]. The process is usually interpreted phenomenologically in terms of the exchange of a strongly interacting net colour-singlet, sometimes referred to as a pomeron [10]. The range of applicability of a universal pomeron across total, elastic, and diffractive processes has a long history of investigation. Despite the wealth of previous data, predictions for the SD contribution at the CERN Large Hadron Coll
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