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Rapidity gaps between jets in photoproduction at HERA
... Within models based on a pomeron with evolving partonic structure, there is thus evidence that any breaking of diffractive factorisation in the present resolved photoproduction data is weaker than that in pp data at larger centre of mass energy. A similar difference between resolved photoproduction at W ∼ 200 GeV and pp interactions at √ s = 1800 GeV is observed in the fraction of dijet events in which there is a rapidity gap between the jets [59]. The Tevatron data also suggest that this fraction is smaller at √ s = 1800 GeV than at √ s = 630 GeV [5,59]. ...
... A similar difference between resolved photoproduction at W ∼ 200 GeV and pp interactions at √ s = 1800 GeV is observed in the fraction of dijet events in which there is a rapidity gap between the jets [59]. The Tevatron data also suggest that this fraction is smaller at √ s = 1800 GeV than at √ s = 630 GeV [5,59]. Data from HERA and the Tevatron on dijet production in diffractive dissociation and on rapidity gaps between jets therefore both support the hypothesis that rapidity gap survival probabilities decrease with increasing centre of mass energy [30] In [8], the ZEUS collaboration presented diffractive dijet photoproduction cross sections measured in a different kinematic region to that studied here. ...
Interactions of the type ep ® e X Yep \rightarrow e X Y are studied, where the component X of the hadronic final state contains two jets and is well separated in rapidity from a leading baryonic system Y. Analyses are performed of both resolved and direct photoproduction and of deep-inelastic scattering with photon virtualities in the range 7.5 < Q2 < 80 GeV27.5 < Q^2 < 80 {\rm GeV^2}. Cross sections are presented where Y has mass MY < 1.6 GeVM_Y < 1.6 {\rm GeV}, the squared four-momentum transferred at the proton vertex satisfies |t| < 1 GeV2|t| < 1 {\rm GeV^2} and the two jets each have transverse momentum pjetT > 5 GeVp^{\rm jet}_T > 5 {\rm GeV} relative to the photon direction in the rest frame of X. Models based on a factorisable diffractive exchange with a gluon dominated structure, evolved to a scale set by the transverse momentum [^(p)]T\hat p_T of the outgoing partons from the hard interaction, give good descriptions of the data. Exclusive q [`(q)]q \bar{q} production, as calculated in perturbative QCD using the squared proton gluon density, represents at most a small fraction of the measured cross section. The compatibility of the data with a breaking of diffractive factorisation due to spectator interactions in resolved photoproduction is investigated.
... Within models based on a pomeron with evolving partonic structure, there is thus evidence that any breaking of diffractive factorisation in the present resolved photoproduction data is weaker than that in pp data at larger centre of mass energy. A similar difference between resolved photoproduction at W ∼ 200 GeV and pp interactions at √ s = 1800 GeV is observed in the fraction of dijet events in which there is a rapidity gap between the jets [59]. The Tevatron data also suggest that this fraction is smaller at √ s = 1800 GeV than at √ s = 630 GeV [5,59]. ...
... A similar difference between resolved photoproduction at W ∼ 200 GeV and pp interactions at √ s = 1800 GeV is observed in the fraction of dijet events in which there is a rapidity gap between the jets [59]. The Tevatron data also suggest that this fraction is smaller at √ s = 1800 GeV than at √ s = 630 GeV [5,59]. Data from HERA and the Tevatron on dijet production in diffractive dissociation and on rapidity gaps between jets therefore both support the hypothesis that rapidity gap survival probabilities decrease with increasing centre of mass energy [30] In [8], the ZEUS collaboration presented diffractive dijet photoproduction cross sections measured in a different kinematic region to that studied here. ...
Interactions of the type ep → eXY are studied, where the component X of the hadronic final state contains two jets and is well separated in rapidity from a leading baryonic system Y. Analyses are performed of both resolved and direct photoproduction and of deep-inelastic scattering with photon virtualities in the range 7.5 < Q
2 < 80 GeV2. Cross sections are presented where Y has mass M
Y
< 1.6 GeV, the squared four-momentum transferred at the proton vertex satisfies |t| < 1 GeV2 and the two jets each have transverse momentum p
Tjet > 5 GeV relative to the photon direction in the rest frame of X. Models based on a factorisable diffractive exchange with a gluon dominated structure, evolved to a scale set by the transverse momentum \(\hat p_T \) of the outgoing partons from the hard interaction, give good descriptions of the data. Exclusive \(q\bar q\) production, as calculated in perturbative QCD using the squared proton gluon density, represents at most a small fraction of the measured cross section. The compatibility of the data with a breaking of diffractive factorisation due to spectator interactions in resolved photoproduction is investigated.
Jet emission at hadron colliders follows simple scaling patterns. Based on
perturbative QCD we derive Poisson and staircase scaling for final state as
well as initial state radiation. Parton density effects enhance staircase
scaling at low multiplicities. We propose experimental tests of our theoretical
findings in Z+jets and QCD gap jets production based on minor additions to
current LHC analyses.
. Preliminary results on dijet production with a rapidity gap between jets in ¯ pp collisions at p s=630 GeV are presented and compared with published results at p s=1800 GeV. INTRODUCTION Results on dijet events with a rapidity gap between jets (Jet-Gap-Jet), attributed to strongly interacting color-singlet exchange (CSE), have been reported by CDF [1,2] and DØ [3] for ¯ pp collisions at p s=1800 GeV at the Tevatron, and by ZEUS [4] for fl Gamma p collisions at HERA. In this paper, we report preliminary results of Jet-Gap-Jet production at p s=630 GeV and compare them with those at 1800 GeV. After a brief review of the 1800 GeV results, we present the the new 630 GeV results, make comparisons and draw conclusions. JET-GAP-JET EVENTS AT p S=1800 GEV In a sample of 10200 single-vertex events with two jets of transverse energy E jet T ? 20 GeV, pseudorapidity 1:8 ! jjj ! 3:5 and j 1 Delta j 2 ! 0, a search was made for events with a rapidity gap in the region of jjj ! 1...
Diffraction studies at HERA are introduced, with reference to other communications to this Conference. Motivations and specific features of the experimental approaches are stressed.
- M Derrick
[22] ZEUS Collaboration,
M. Derrick et al., Phys. L&t. B 348
(1995) 665.
- R S Fletcher
- T Stelzer
R.S. Fletcher and T. Stelzer, Phys. Rev. D 48 (1993) 5162.
- J References
- Huth
References
[ 171 J. Huth et al., in: Proceedings of the 1990 DPF Summer
Study on High Energy Physics, Snowmass, Colorado, ed.
E.L. Berger (World Scientific, Singapore, 1992) 134;
UAl Collaboration,
G. Amison et al., Phys. I&t. B 123
(1983) 115.
[II
121
r31
[41
[51
161
[71
181
[91
- A Martin
- W J Stirling
- R G Roberta
A. Martin, W.J. Stirling and R.G. Roberta, Phys. Rev. D 50
( 1994) 6734.
- G A Schuler
- T Sjijstrand
G.A. Schuler and T. Sjijstrand, Phys. Lett. B 300 f 1993)
169; Nucl. Phys. B 407 (1993) 539;
- A H Mueller
- W.-K Tang
A.H. Mueller and W.-K. Tang, Phys. L&t. B 284 (1992)
123.
- T Sjbstrand
- M Van Zijl
T. SjBstrand and M. van Zijl, Phys. Rev. D 36 (1987) 2019;
- C Alvisi
C. Alvisi et al., Nucl. Instr. Meth. A 305 (1991) 30.
- M Gliick
- E Reya
- A Vogt
M. Gliick, E. Reya and A. Vogt, Phys. Rev. D 46 (1992)
1973.
- Cdf Collaboration
- Abe
CDF Collaboration, E Abe, et al., Phys. Rev. I.&t. 74 (1995)
855.
- B Foster
B. Foster et al., Nucl. Phys. B, Proc. Suppl. B 32 (1993)
181.
- G D Agostini
G. D'Agostini, Nucl. Instr. Meth. A 367 (1995) 487.
- A Andresen
A. Andresen et al., Nucl. Instr. Meth. A 309 (1991) 101;
- I Hl Collaboration
- Abt
Hl Collaboration,
I. Abt et al., Nucl. Phys. B 429 (1994)
- A Bernstein
A. Bernstein et al., Nucl. Instr. Meth. A 336 (1993) 23.
- J Andmszkdw
J. Andmszkdw et al., DESY 92-066 (1992).
1151 ZEUS Collaboration,
M. Derrick et al., Phys. Lett. B 316
(1993) 412.
- M Derrick
M. Derrick et al., Nucl. Instr. Meth. A 309 (1991) 77;