Observation of Color-Transparency in Diffractive Dissociation of Pions

Aitala, E. M.; Amato, S.; Anjos, J. C.; Appel, J. A.; Ashery, D.; Banerjee, S.; Bediaga, I.; Blaylock, G.; Bracker, S. B.; Burchat, P. R.; Burnstein, R. A.; Carter, Thomas; Carvalho, H. S.; Copty, N.; Cremaldi, L.; Darling, C.; Denisenko, K.; Devmal, S.; Fernández, A.; Fox, G. F.; Gagnon, P.; Gerzon, S.A.; Göbel, C.; Gounder, K.; Halling, A. M.; Herrera, G.; Hurvits, G.; James, C.; Kasper, P. A.; Kwan, S.; Langs, D. C.; Leslie, J. R.; Lichtenstadt, J.; Lundberg, B.; MayTal‐Beck, S.; Meadows, B.; Neto, J. R. T. de Mello; Mihalcea, D.; Milburn, R. H.; Miranda, J. M. De; Napier, A.; Nguyen, A.; D’Oliveira, A.; O’Shaughnessy, K.; Peng, K.C.; Perera, L. P.; Purohit, M. V.; Quinn, B.; Radeztsky, S.; Rafatian, A.; Reay, N. W.; Reidy, J.; Reis, A. C. dos; Rubin, H. A.; Sanders, D. A.; Santha, A.K.S.; Santoro, A. F. S.; Schwartz, A. J.; Sheaff, M.; Sidwell, R. A.; Slaughter, A. J.; Sokoloff, M. D.; Solano, J.; Stanton, N. R.; Stefanski, R. J.; Stenson, K.; Summers, D. J.; Takach, S.; Thorne, K. A.; Tripathi, A.; Watanabe, Shuji; Weiss-Babai, R.; Wiener, J.; Witchey, N.; Wolin, E.; Yang, S.; Duan, Yi; Yoshida, S.; Zaliznyak, R.; Zhang, C.

doi:10.1103/physrevlett.86.4773

Cited by 120 publications

(117 citation statements)

References 39 publications

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“…Another diffractive process suggested in [22], coherent production of high-p T back-to-back jets on nuclei, also revealed a strong signal of CT [23] in good agreement with theoretical estimates [24]. In this process the nucleus remains intact, which is possible due to sufficiently high energy.…”

Section: B Dipole Cross Section and Color Transparencysupporting

confidence: 65%

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Diffraction in QCD

Kopeliovich¹,

Potashnikova²,

Schmidt³

2007

Braz. J. Phys.

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This lecture presents a short review of the main features of diffractive processes and QCD inspired models. It includes the following topics: (1) Quantum mechanics of diffraction: general properties; (2) Color dipole description of diffraction; (3) Color transparency; (4) Soft diffraction in hard reactions: DIS, Drell-Yan, Higgs production; (5) Why Pomerons interact weakly; (6) Small gluonic spots in the proton; (7) Diffraction near the unitarity bound: the Goulianos-Schlein "puzzle"; (8) Diffraction on nuclei: diffractive Color Glass; (9) CGC and gluon shadowing.

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Section: B Dipole Cross Section and Color Transparencysupporting

confidence: 65%

“…11. This is not a surprise, the energy dependence is slowed down by presence of the first energy independent term in (23). If to approximate the cross section (23) by the simple power dependence s ε , then the effective exponent reads,…”

Section: A Total Cross Sectionmentioning

confidence: 99%

Diffraction in QCD

Kopeliovich¹,

Potashnikova²,

Schmidt³

2007

Braz. J. Phys.

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“…The integrated diffractive rate will then scale as A 2 /R 2 A ∼ A 4/3 . This is in fact what has been observed by the E791 collaboration at FermiLab for 500 GeV incident pions on nuclear targets [39].…”

Section: Diffraction Dissociation As a Tool To Resolve Hadron Substrusupporting

confidence: 61%

Dynamic versus Static Structure Functions and Novel Diffractive Effects in QCD

Brodsky¹

2009

AIP Conference Proceedings

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Abstract. Initial-and final-state rescattering, neglected in the parton model, have a profound effect in QCD hard-scattering reactions, predicting single-spin asymmetries, diffractive deep inelastic scattering, diffractive hard hadronic reactions, the breakdown of the Lam Tung relation in DrellYan reactions, and nuclear shadowing and non-universal antishadowing-leading-twist physics not incorporated in the light-front wavefunctions of the target computed in isolation. I also discuss the use of diffraction to materialize the Fock states of a hadronic projectile and test QCD color transparency, and anomalous heavy quark effects. The presence of direct higher-twist processes where a proton is produced in the hard subprocess can explain the large proton-to-pion ratio seen in high centrality heavy ion collisions. I emphasize the importance of distinguishing between static observables such as the probability distributions computed from the square of the light-front wavefunctions versus dynamical observables which include the effects of rescattering. NOVEL FEATURES OF DIFFRACTIVE DEEP INELASTIC SCATTERINGA remarkable feature of deep inelastic lepton-proton scattering at HERA is that approximately 10% events are diffractive [1,2]: the target proton remains intact, and there is a large rapidity gap between the proton and the other hadrons in the final state. This observation presents a paradox: if one chooses the conventional parton model frame, the virtual photon interacts with a quark constituent with light-cone momentum fraction x = k + /p + = x b j . Furthermore, the gauge link associated with the struck quark (the Wilson line) becomes unity in light-cone gauge A + = 0. Thus the struck "current" quark apparently experiences no final-state interactions. Since the light-front wavefunctions ψ n (x i , k ⊥i ) of a stable hadron are real, it appears impossible to generate the required imaginary phase associated with pomeron exchange, let alone large rapidity gaps. This paradox was resolved by Hoyer, Marchal, Peigne, Sannino and myself [3]. Consider the case where the virtual photon interacts with a strange quark-the ss pair is assumed to be produced in the target by gluon splitting. In the case of Feynman gauge, the struck s quark continues to interact in the final state via gluon exchange as described by the Wilson line. The final-state interactions occur at a light-cone time ∆τ 1/ν shortly after the virtual photon interacts with the struck quark. When one integrates over the nearly-on-shell intermediate state, the amplitude acquires an imaginary part. Thus the rescattering of the quark produces a separated color-singlet ss and an imaginary phase.

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“…The cross section for this process has a similar structure [52]: due to the rapid increase of the gluon density with energy one expects the cross section for pion diffraction into two jets to be much larger than that in the case of the fixed-target experiment E791 at FNAL which has reported the first evidence for this effect [53]. …”

Section: Pion Diffraction Into Two Jetsmentioning

confidence: 84%

A full-acceptance detector at the LHC (FELIX)

Ageev¹,

Akhobadze²,

Alvero³

et al. 2002

J. Phys. G: Nucl. Part. Phys.

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The FELIX collaboration had proposed the construction of a full-acceptance detector for the LHC. The primary mission of FELIX was the study of QCD: to provide comprehensive and definitive observations of a very broad range of strong-interaction processes. This document contains an extensive discussion of this physics menu. In a further paper the FELIX detector will be reviewed. Contents HISTORYWith the advent of the large hadron collider (LHC), we are on the threshold of a new era in high-energy physics. With instrumentation in the form of dedicated experiments of unprecedented precision and complexity, the LHC will move significantly beyond the current high-energy frontier, and dramatically improve our understanding of particle physics at the highest energies and shortest distances accessible to man.As currently planned, however, the LHC experimental programme is incomplete. Moreover, these deficiencies continue and extend what has been a gap in the experimental programme of all hadron colliders. The problem lies in the design of the detectors instrumenting hadron colliders: they are all optimized for rare, high-pt events. These 'general purpose' detectors are anything but that. Rather, they are designed to explore extreme shortdistance phenomena. Without intending to demean the efforts of the collaborations which have built or are building these detectors, it is nevertheless these events in which the theorists are most confident that they understand the physics, and are in many ways experimentally most accessible.While there is no doubt that such physics and such detectors should be the centrepiece of any programme of hadron collider physics, it seems much less clear that they should be the only item on the agenda. Indeed, it can be argued that a full-acceptance detector, capable of detecting and measuring each particle in an event well, may have the greatest discovery potential. Alas, the absence of any experimental effort in this direction in the collider era has meant that both theoretical investigations and experimental design of such detectors has languished, to the point that many in the community have come to think of high-pt physics as the last frontier in particle physics.The FELIX collaboration sought to rectify this situation. With support from the CERN administration, some 160 physicists collaborated in preparing the FELIX LoI. Many of these could not officially join the collaboration, and so their help could only be acknowledged. While the FELIX proposal was never officially killed, it was nevertheless effectively killed without the collaboration making a formal presentation to the LHC committee.All of this, of course, is history, and not very pleasant history at that. The motivation for a full-acceptance detector remains, however, and interest on the part of the broader community, despite the implications of this history, remains high. Because of this, the FELIX collaboration, together with those who helped but were not members, believes that it is important to document the physics of a ...

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Observation of Color-Transparency in Diffractive Dissociation of Pions

Cited by 120 publications

References 39 publications

Diffraction in QCD

Diffraction in QCD

Dynamic versus Static Structure Functions and Novel Diffractive Effects in QCD

A full-acceptance detector at the LHC (FELIX)

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