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Diffractive production of massive states

Description: The nature of the pomeron, e.g. its quark and gluon structure in QCD, can be investigated by studying pomeron-proton interactions producing high E{sub T} jets, heavy flavors, W/Z and lepton pairs. This study was initiated at the CERN S{ital p}{anti {ital p}}S collider and is now pursued at the Tevatron. A hard pomeron also manifests itself as a rapidity gap between two high E{sub T} jets. In both cases there is evidence that the pomeron sometimes behaves like a single gluon. Pomeron-pomeron interactions may be extremely interesting.
Date: June 1, 1996
Creator: Albrow, M.G.
Partner: UNT Libraries Government Documents Department

Transverse energy carried by charged particles in anti pp and pp collisions at the CERN intersecting storage rings

Description: Global features of anti pp and pp collisions at a c.m.s. energy of 53 GeV are compared as functions of the summed transverse energy ..sigma../sub c/ E/sub T/ of charged particles in the central region absolute value y < 0.8. They are found to be very similar for ..sigma../sub c/ E/sub T/ up to approx. = to 12 GeV. For both types of collisions, all gross features for ..sigma../sub c/ E/sub T/ up to 6 to 8 GeV are well described by a model that folds together the inclusive multiplicity and p/sub T/ distributions. At higher values of ..sigma../sub c/ E/sub T/ the data deviate increasingly from the model.
Date: January 1, 1982
Creator: Akesson, T.; Albrow, M.G. & Almehed, S.
Partner: UNT Libraries Government Documents Department

Charge correlations in deep inelastic proton-proton interactions at the CERN ISR: the axial field spectrometer collaboration

Description: The production of charged particles in pp collisions at ..sqrt..s = 63 GeV with an identified high p/sub T/ trigger particle emitted in the central region is studied. The measurements were performed at the CERN ISR using the Axial Field Spectrometer. The dependence of the ratio between positively and negatively charged particles on the identity, the transverse momentum and the rapidity of the trigger particle is investigated both in the system recoiling from the trigger particle and at small angles with respect to the trigger particle. The recoil system opposite to a positively charged trigger particle is nearly neutral, but shows a positive excess for negatively charged trigger particles. On the trigger side a charge compensating effect is seen, strongest for negatively charged trigger particles.
Date: January 1, 1982
Creator: Akesson, T.; Albrow, M.G. & Almehed, S.
Partner: UNT Libraries Government Documents Department

Comparison of high-p/sub T/ particle production in pp and p anti p interactions at the CERN ISR

Description: We have measured the production of neutral and charged hadrons with transverse momenta in the range 2 GeV/c to 6 GeV/c at ..sqrt..s = 63 GeV. Data have been obtained under identical experimental conditions in pp and p anti p collisions. The comparison of the inclusive spectra shows no statistically significant difference over the p/sub T/ range studied.
Date: January 1, 1982
Creator: Akesson, T.; Albrow, M.G. & Almehed, S.
Partner: UNT Libraries Government Documents Department

Transverse momentum structures of charged particle final states from proton-proton collisions with a charged trigger particle of large transverse momentum

Description: A sample of proton-proton collisions at ..sqrt.. s = 63 GeV with a (trigger) charged particle of transverse momentum in the range 4 to 12 GeV/c and vertical bar rapidity vertical bar < 1 is studied. The events were obtained with the Axial Field Spectrometer at the CERN ISR (experiment R807). Preliminary results are reported from an investigation of the distribution of the transverse momentum vectors of the observed charged particles in the central rapidity region associated with the trigger particle. It is found that the pattern of transverse momentum vectors of the observed charged particles in the central rapidity region associated with the trigger particle. It is found that the pattern of transverse momentum vectors of the charged particles observed in a given event is strongly dependent on the amount of transverse energy which is carried by the associated charged particles observed in the event. When the transverse energy is large (> 10 GeV/c within vertical bar rapidity vertical bar < 1), a large fraction (approx. 50%) of the events have the transverse momentum vectors of the associated charged particles collimated in narrow jets around an axis close in azimuth (within approx. 20/sup 0/) to the trigger particle.
Date: January 1, 1982
Creator: Akesson, T.; Albrow, M.G. & Almehed, S.
Partner: UNT Libraries Government Documents Department

Blois V: Experimental summary

Description: The author gives a summary talk of the best experimental data given at the Vth Blois Workshop on Elastic and Diffractive Scattering. He addresses the following eight areas in his talk: total and elastic cross sections; single diffractive excitation; electron-proton scattering; di-jets and rapidity gaps; areas of future study; spins and asymmetries; high-transverse momentum and masses at the Tevatron; and disoriented chiral condensates and cosmic radiation.
Date: September 1, 1993
Creator: Albrow, M. G.
Partner: UNT Libraries Government Documents Department

Hard diffraction and rapidity gaps

Description: I describe the evolution of experiments at hadron colliders on (a) high mass diffraction (b) double pomeron exchange, from the ISR through the Sp{bar p}S to the Tevatron. I emphasize an experimental approach to the question: ``What is the pomeron?``
Date: August 1, 1994
Creator: Albrow, M. G.
Partner: UNT Libraries Government Documents Department

Study of charged particles associated with high-p/sub T/ photons and pions

Description: We report on the distributions of charged particles produced in association with high p/sub T/ prompt photons and neutral pions in pp collisions at ..sqrt.. s = 63 GeV and theta = 90/sup 0/ in the centre of mass. We find photons to be relatively unaccompained by other particles at small angles with respect to the photon, and thereby extract a measurement of the fraction of prompt photons due to bremsstrahlung production. The relative density of positive to negative particles in the system recoiling from the photon has been measured and compared with QCD motivated calculations.
Date: July 1, 1982
Creator: Akesson, T.; Albrow, M.G. & Almehed, S.
Partner: UNT Libraries Government Documents Department

VIIth Blois Workshop summary: experimental

Description: The Blois Workshop has become a conference not just restricted to diffractive scattering, but including topics such as searches for SUSY and Higgs, measurements of the top mass and b-decays. I will mention these briefly but will mostly discuss new results (and needed future measurements) in hard diffraction at HERA and the Tevatron.
Date: October 1, 1997
Creator: Albrow, M.G.
Partner: UNT Libraries Government Documents Department

Di-jet production by double pomeron exchange in CDF

Description: We have studied events with a high-x{sub F} antiproton and two central jets with E{sub T} > 7 GeV in CDF, in p{anti p} collisions at {radical}s = 1800 GeV. We find an excess of events with a rapidity gap at least 3.5 units wide in the proton direction, which we interpret as di-jet production in double pomeron exchange events.
Date: May 1, 1998
Creator: Albrow, M.G.
Partner: UNT Libraries Government Documents Department

Some experimental considerations of the QCD Group

Description: For experimental investigation of quantum chromodynamics, the preferred machine question is dominated by such issues as how much luminosity is needed and which machine is practical (to get approved, build fast, run reliably, etc.). It is concluded that pile-up problems for localized E/sub T/ triggers are not serious. For high luminosity QCD studies a philosophy is envisaged which is predominantly calorimetric and ignores the low p/sub t/ activity. It is suggested that consideration be given to the concept of a jet spectrometer for jet fragmentation with momentum measurement. (LEW)
Date: January 1, 1984
Creator: Fields, T.H.; Albrow, M.G. & Boggild, H.
Partner: UNT Libraries Government Documents Department

QCD subgroup on diffractive and forward physics

Description: The goal is to understand the pomeron, and hence the behavior of total cross sections, elastic scattering and diffractive excitation, in terms of the underlying theory, QCD. A description of the basic ideas and phenomenology is followed by a discussion of hadron-hadron and electron-proton experiments. An appendix lists recommended diffractive-physics terms and definitions. 44 refs., 6 figs.
Date: October 1, 1996
Creator: Albrow, M.G.; Baker, W. & Bhatti, A.
Partner: UNT Libraries Government Documents Department

Hard diffraction in CDF

Description: The aim of these studies is to use hard (large Q{sup 2}) processes to investigate the partonic nature of the pomeron. We have measured events with large rapidity gaps between balancing high E{sub T} jets, events with two forward (same-side) jets and a large gap (diffractive di-jet production), diffractive W{sup {+-}} production and diffractive heavy flavor (J/{psi} and b-quark) production. Candidate events of the type double-pomeron {yields} di-jet are observed. I close with a look at the future (Run II).
Date: October 1, 1997
Creator: Albrow, M.G.
Partner: UNT Libraries Government Documents Department

QCD subgroup on diffractive and forward physics

Description: Over the last few years, there has been a resurgence of interest in small-x or diffractive physics. This has been due to the realization that perturbative QCD techniques may be applicable to what was previously thought of as a non-perturbative problem and to the opening up of new energy regimes at HERA and the Tevatron collider. The goal is to understand the pomeron, and hence the behavior of total cross sections, elastic scattering and diffractive excitation, in terms of the underlying theory, QCD. This paper is divided into experiments of hadron-hadron colliders and electron-proton colliders.
Date: September 1, 1997
Creator: Albrow, M.G.; Baker, W. & Bhatti, A.
Partner: UNT Libraries Government Documents Department

Diffractive dijet production in CDF

Description: We have studied events with a high-x{sub F} antiproton and two central jets in CDF, with p{anti p} collisions at {radical}s = 630 and 1800 GeV. These events are expected to be dominated by diffraction (pomeron exchange). The jet E{sub T} spectra are very similar to those of non-diffractively produced jets but slightly steeper; their azimuthal difference {Delta}{phi} is more peaked at 180{degree}.
Date: April 17, 1998
Creator: Albrow, M.G.
Partner: UNT Libraries Government Documents Department

Central Exclusive Particle Production at High Energy Hadron Colliders

Description: We review the subject of central exclusive particle production at high energy hadron colliders. In particular we consider reactions of the type A + B {yields} A + X + B, where X is a fully specified system of particles that is well separated in rapidity from the outgoing beam particles. We focus on the case where the colliding particles are strongly interacting and mainly they will be protons (or antiprotons) as at the ISR, Sp{bar p}S, Tevatron and LHC. The data are surveyed and placed within the context of theoretical developments.
Date: June 1, 2010
Creator: Albrow, M.G.; /Fermilab; Coughlin, T.D.; London, /University Coll.; Forshaw, J.R. & U., /Manchester
Partner: UNT Libraries Government Documents Department

Study of exclusive central hadron production at the ISR as a search for gluonium states: the axial field spectrometer collaboration

Description: We present a preliminary report on a study of the exclusive reaction pp ..-->.. pph/sup +/h/sup -/ (h = ..pi..,K,p) at ..sqrt..s = 63 GeV and ..sqrt..s = 45 GeV, with h/sup +/ and h/sup -/ in the central region. This reaction has been suggested as a method of searching for gluonium states. The mass distributions in the ..pi../sup +/..pi../sup -/ system appear to be identical at the two values of ..sqrt..s. They show a rapid order of magnitude decrease in cross-section at 1000 MeV/c/sup 2/ and 1500 MeV/c/sup 2/. Further structure is observed above 2000 MeV/c/sup 2/.
Date: January 1, 1983
Creator: Akesson, T.; Albrow, M.G.; Almehed, S.; Batley, R.; Benary, O.; Boeggild, H. et al.
Partner: UNT Libraries Government Documents Department

Properties of jets in high-E/sub T/ events produced in pp collisions at. sqrt. s = 63 GeV

Description: The properties of jets in high-E/sub tau/ events produced in pp collisions at ..sqrt..s = 63 GeV have been studied at the CERN Intersecting Storage Rings. The fragmentation of the jets is found to be similar to that of jets produced in e/sup +/e/sup -/ annihilation. The jets are wider than calculated from a constituent scattering model with no hard bremsstrahlung component. The charge correlations of positive and negative particles show differences consistent with expectation from valence-quark scattering. 11 references.
Date: July 1, 1983
Creator: Akesson, T.; Albrow, M.G.; Almehed, S.; Batley, R.; Benary, O.; Boggild, H. et al.
Partner: UNT Libraries Government Documents Department

Observation of Exclusive Electron-Positron Production in Hadron-Hadron Collisions

Description: We present the first observation of exclusive e{sup +}e{sup -} production in hadron-hadron collisions, using p{bar p} collision data at {radical}s = 1.96 TeV taken by the Run II Collider Detector at Fermilab, and corresponding to an integrated luminosity of 532 pb{sup -1}. We require the absence of any particle signatures in the detector except for an electron and a positron candidate, each with transverse energy E{sub T} &gt; 5 GeV and pseudorapidity |{eta}| &lt; 2. With these criteria, 16 events are observed compared to a background expectation of 1.9 {+-} 0.3 events. These events are consistent in cross section and properties with the QED process p{bar p} {yields} p + e{sup +}e{sup -} + {bar p} through two-photon exchange. The measured cross section is 1.6{sub -0.3}{sup +0.5}(stat) {+-} 0.3(syst) pb. This agrees with the theoretical prediction of 1.71 {+-} 0.01 pb.
Date: November 1, 2006
Creator: Abulencia, A.; Adelman, J.; Affolder, T.; Akimoto, T.; Albrow, M.G.; Ambrose, D. et al.
Partner: UNT Libraries Government Documents Department

Particle ratios at high transverse momentum in pp collisions at. sqrt. s = 63 GeV and correlations between high p/sub T/ identified charged particles and associated identified charged particles

Description: The production of identified charged particles in pp collisions at ..sqrt..s = 63 GeV with an identified high p/sub T/ trigger particle emitted in the central region is studied. The measurements were performed at the CERN ISR using the Axial Field Spectrometer. Trigger particle ratios, sigma(..pi../sup + -/)/ sigma(all/sup + -/), sigma(K/sup + -/) and sigma(p/sup + -/)/sigma(all/sup + -/) are presented for p/sub T/ from 5 GeV/c to 8 GeV/c. In addition sigma(..pi../sup + -/)/sigma(all/sup + -/) is presented in the p/sub T/ region from 2.5 GeV/c to 4.5 GeV/c. The charge compensation in the hemisphere containing the trigger particle is shown to depend strongly on the identity of the trigger particle and on the identity of the associated particles. 13 references.
Date: January 1, 1983
Creator: Akesson, T.; Albrow, M. G.; Almehed, S.; Batley, R.; Benary, O.; Boggild, H. et al.
Partner: UNT Libraries Government Documents Department

Observation of Exclusive Gamma Gamma Production in $p \bar{p}$ Collisions at $\sqrt{s}=1.96$ TeV

Description: We have observed exclusive {gamma} production in proton-antiproton collisions at {radical}s = 1.96 TeV, using data from 1.11 {+-} 0.07 fb{sup -1} integrated luminosity taken by the Run II Collider Detector at Fermilab. We selected events with two electromagnetic showers, each with transverse energy E{sub T} &gt; 2.5 GeV and pseudorapidity |{eta}| &lt; 1.0, with no other particles detected in -7.4 &lt; {eta} &lt; +7.4. The two showers have similar E{sub T} and azimuthal angle separation {Delta}{phi} {approx} {pi}; 34 events have two charged particle tracks, consistent with the QED process p{bar p} {yields} p + e{sup +}e{sup -} + {bar p} by two-photon exchange, while 43 events have no charged tracks. The number of these events that are exclusive {pi}{sup 0}{pi}{sup 0} is consistent with zero and is &lt; 15 at 95% C.L. The cross section for p{bar p} {yields} p + {gamma}{gamma} + {bar p} with |{eta}({gamma})| &lt; 1.0 and E{sub T} ({gamma}) &gt; 2.5 GeV is 2.48{sub -0.35}{sup +0.40}(stat){sub -0.51}{sup +0.40}(syst)pb.
Date: December 1, 2011
Creator: Aaltonen, T.; Albrow, M. G.; Alvarez Gonzalez, B.; Amerio, S.; Amidei, D.; Anastassov, A. et al.
Partner: UNT Libraries Government Documents Department

A Search for the Higgs Boson Using Very Forward Tracking Detectors with CDF

Description: The authors propose to add high precision track detectors 55 m downstream on both (E and W) sides of CDF, to measure high Feynman-x protons and antiprotons in association with central states. A primary motivation is to search for the Higgs boson, and if it is seen to measure its mass precisely. The track detectors will be silicon strip telescopes backed up by high resolution time-of-flight counters. They will have four spectrometer arms, for both sides of the p and {bar p} beams. The addition of these small detectors effectively converts the Tevatron into a gluon-gluon collider with {radical}s from 0 to {approx} 200 GeV. This experiment also measures millions/year clean high- |t| elastic p{bar p} scattering events and produce millions of pure gluon jets. Besides a wealth of other unique QCD studies they will search for signs of exotic physics such as SUSY and Large Extra Dimensions. They ask the Director to ask the PAC to take note of this Letter of Intent at its April meeting, to consider a proposal at the June meeting and to make a decision at the November 2001 meeting. They request that the Directorage ask the Beams Division to evaluate the consequences and cost of the proposed Tevatron modifications, and CDF to evaluate any effect on its baseline program and to review the technical aspects of the detectors, DAQ and trigger integration.
Date: March 1, 2001
Creator: Albrow, M. G.; Atac, M.; Booth, P.; Crosby, P.; Dunietz, I.; Finley, D. A. et al.
Partner: UNT Libraries Government Documents Department

Search for W and Z bosons in the reaction anti-p p ---> 2 jets + gamma at s**(1/2) = 1.8-TeV

Description: The authors present a study of the dijet invariant mass distribution for the reaction {bar p}p {yields} 2 jets+{gamma} + X, at a center of mass energy of 1.8 TeV, using data collected by the CDF experiment. They compare the data to predictions for the production of a photon with two jets, together with the resonant processes {bar p}p {yields} W/Z + {gamma} + X, in which the W and Z bosons decay hadronically. A fit is made to the dijet invariant mass distribution combining the non-resonant background and resonant processes. They use the result to establish a limit for the inclusive production cross section of W/Z + {gamma} with hadronic decay of the W and Z bosons.
Date: July 1, 2005
Creator: Acosta, D.; Affolder, Anthony A.; Albrow, M. G.; Ambrose, D.; Amidei, D.; Anikeev, K. et al.
Partner: UNT Libraries Government Documents Department