The ATLAS physics program

Royon, C.

doi:10.22323/1.106.0088

Cited by 3 publications

(3 citation statements)

References 5 publications

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“…There has recently been a renewal of interest in studies of central exclusive production (CEP) processes in high-energy proton-(anti)proton collisions (see [1][2][3][4] for reviews), both theoretically [5][6][7][8][9][10][11][12][13][14] and experimentally [4,[15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] (see [32,33] for reviews). The CEP of an object X may be written in the form pp(p) → p + X + p(p) , (1.1) where + signs are used to denote the presence of large rapidity gaps.…”

Section: Introductionmentioning

confidence: 99%

The phenomenology of central exclusive production at hadron colliders

et al. 2012

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Central exclusive production (CEP) processes in high-energy hadron-hadron collisions provide an especially clean environment in which to measure the nature and quantum numbers (in particular, the spin and parity) of new resonance states. Encouraged by the broad agreement between experimental measurements and theoretical predictions based on the Durham approach, we perform a detailed phenomenological analysis of γγ and meson pair CEP final states, paying particular attention to the theoretical uncertainties in the predictions, including those from parton distribution functions, higher-order perturbative corrections, and non-perturbative and proton dissociation contributions. We present quantitative cross-section predictions for these CEP final states at the RHIC, Tevatron and LHC colliders.

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Section: Introductionmentioning

confidence: 99%

The phenomenology of central exclusive production at hadron colliders

et al. 2012

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“…The resolution and the acceptance of the hadron tagging detector are fixed by the LHC high-lunimosity beam optics. The hadron tagging detectors use the FPtract program [54][55][56] to track the path of the hadrons through the LHC lattice so as to completely find out the acceptance. The acceptance of the forward detectors is controlled by the distance of the active edge of the detector from the beam, which fixes the smallest measurable energy loss of the outgoing hadrons, and the space of the LHC beam elements between the interaction point and the forward detector.…”

Section: A Forward Hadron Taggingmentioning

confidence: 99%

Photoproduction of J/ψ with forward hadron tagging in hadronic collisions

2019

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We study the photoproduction of J/ψ using the NRQCD formalism with forward hadron tagging at the Large Hadron Collider. We estimate the total cross sections and event rates with and without nuclear shadowing effects in high energy proton-proton, proton-nucleus and nucleus-nucleus collisions. Our results show that the processes which involve J/ψ photoproduction depend on the choice of forward detector acceptances ξ. Under some precise cut of p J/ψ T and z J/ψ kinematic variables, we find that the distributions of photoproduction of J/ψ are led by the Fock state 1 S1 . The total cross sections and event rates will be smaller if the nuclear shadowing effects are considered. The processes give a crucial photoproduction signature at the LHC with forward detector acceptances. The exploration and the detection of the interactions will be useful for studying the mechanism of heavy quarkonium production. I. INTRODUCTIONSince the discovery of heavy quarkonia in the mid-1970s, their production and decay become reliable tools to improve our understanding of theoretical aspects of quantum chromodynamics (QCD) from the hard region, where the strong interaction is realized with a large momentum transfer, to the soft region, where the strong interaction is carried out with a small momentum transfer. These production and decay of heavy quarkonia are studied under the non-relativistic quantum chromodynamics (NRQCD) due to the large mass of heavy quarks (m c ∼ 1.5 GeV, m b ∼ 4.75 GeV). The full description of the theoretical framework was proposed by Bodwin, Braaten and Lepage(BBL) [1]. It factorizes the quarkonium production in terms of short distance QCD cross sections and long distance matrix elements (LDMEs). The former can be pertubatively evaluated in series of the running coupling constant α s while the latter is the probability for a heavy QQ pair with spin S, orbital angular momentum L, total angular momentum J, and color multiplicity a = 1 (color-singlet), 8 (color-octet) to evolve into a physical heavy quarkonium state. The value of LDMEs can either be calculated by utilizing non-perturbative methods or extracted phenomenologically from data [2], i.e., QCD lattice simulations or measurements in some production processes. The QQ pair is generated from the partonic interaction at short distances in color singlet (CS) or in color-octet (CO) states and hadronizes into physical CS observable by emitting soft gluons non-perturbatively. The effect of LDME contribution has a hierarchically ordered scaling with v [3], v being the nonrelativistic velocity of Q orQ in the QQ rest frame. The essence of this theory can now be systematically shortened by the double expansion in powers of α s and v. A lot of phenomenological approaches of this framework are meticulously narrated in Refs [4,5,7,8], taking into account the complete and spanned structure of the QQ Fock space by the state n = 2S+1 L (a) J . However, the golden age of the NRQCD theory has been to address the limitations of the early proposed models from which it establishes...

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“…1 illustrates the former for a typical parton level subprocess where X is a pair of quark jets as an example. This process will be measured in the near future by the ATLAS experiment using forward spectrometers [20], and different models of diffraction can then be tested.…”

Section: Colour Singlet Exchange Modelsmentioning

confidence: 99%

DiffractiveW±production at hadron colliders as a test of color singlet exchange mechanisms

et al. 2013

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We revisit diffractive and exclusive W ± X production at hadron colliders in different models for soft colour exchanges. The process pp → p[W ± X]p, and in particular a W ± charge asymmetry, has been suggested as a way to discriminate diffractive processes as being due to pomeron exchange in Regge phenomenology or QCD-based colour reconnection models. Our detailed analysis of the latter models at LHC energies shows, however, that they give similar results as pomeron models for very leading protons and central W ± X production, including a vanishing W ± charge asymmetry. We demonstrate that soft colour exchange models provide a continuous transition from diffractive to inelastic processes and thereby include the intrinsic asymmetry of inelastic interactions while being at the same time sensitive to the underlying hadronisation models. Such sensitivity also concerns the differential distributions in proton momentum and W ± transverse momentum which opens possibilities to discriminate between different colour reconnection models. * Gunnar.Ingelman@physics.uu.se † Roman.Pasechnik@thep.lu.se ‡ Johan.Rathsman@thep.lu.se § Dominik.Werder@physics.uu.se

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The ATLAS physics program

Abstract: On behalf of the ATLAS experimentWe describe the ATLAS Forward Physics Program at low luminosity using the rapidity gap method and a dedicated detector called ALFA to tag the protons. We also describe the physics topics of the ATLAS Forward Physics Project at high instantaneous luminosity.

Cited by 3 publications

References 5 publications

The phenomenology of central exclusive production at hadron colliders

The phenomenology of central exclusive production at hadron colliders

Photoproduction of J/ψ with forward hadron tagging in hadronic collisions

DiffractiveW±production at hadron colliders as a test of color singlet exchange mechanisms

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