... 3. Expression of Interest for a "BEAM-DUMP" upgrade of L3 for the LHC (LHCC 95-17 a... more ... 3. Expression of Interest for a "BEAM-DUMP" upgrade of L3 for the LHC (LHCC 95-17 and addendum LHCC 95-22; P.Fisher, J.Kirkby). ... HGFischer, G.Hall, J.Harvey, HJHilke, G.Kellner, U.Koetz, P.Lazeyras, I.Lehraus, M.Mazzucato, R.Mount, M.Mur, E.Petrolo, S.Quinton, W.Smith ...
... range systems for calorimetry. Status Reports of approved projects presented at the open sess... more ... range systems for calorimetry. Status Reports of approved projects presented at the open session. RD-29 A mixed analog-digital radiation hard technology for high energy physics applications (LHCC 95-13). F.Bourgeois gave an ...
ABSTRACT Starting with partial-wave amplitudes for πN-->Nπ and πN-->several isobar-... more ABSTRACT Starting with partial-wave amplitudes for πN-->Nπ and πN-->several isobar-model states of Nππ, we are able to apply the constraint of unitarity (using the K matrix). This permits the removal of the overall phase ambiguity of the isobar amplitudes at each energy. The K-matrix fits generate a smooth prescription for the T-matrix amplitudes, enabling us to search the complex energy plane for poles. The uniqueness of these poles is demonstrated by doing Breit-Wigner refits to the fitted T-matrix amplitudes. The success of the refits and the obvious interpretation justifies a simple determination of coupling signs for which there can be checks with theory.
The exclusive production of ρ^0 mesons in deep inelastic electron-proton scattering has been stud... more The exclusive production of ρ^0 mesons in deep inelastic electron-proton scattering has been studied using the ZEUS detector. Cross sections have been measured in the range 7 < Q^2 < 25 GeV^2 for γ^*p centre of mass (c.m.) energies from 40 to 130 GeV. The γ^*p →ρ^0 p cross section exhibits a Q^-(4.2 ± 0.8 ^+1.4_-0.5) dependence and both longitudinally and transversely polarised ρ^0's are observed. The γ^*p →ρ^0 p cross section rises strongly with increasing c.m. energy, when compared with NMC data at lower energy, which cannot be explained by production through soft pomeron exchange. The data are compared with perturbative QCD calculations where the rise in the cross section reflects the increase in the gluon density at low x. the gluon density at low x.
A high luminosity upgrade of HERA will allow the measurement of standard model parameters and the... more A high luminosity upgrade of HERA will allow the measurement of standard model parameters and the neutral current couplings of quarks. These results will have to be consistent with other precision measurements or indicate traces of new physics. The analysis of W production will complement future results of LEP 2 and the Tevatron. We summarize the main results and conclusions obtained by the working group on Electroweak Physics concerning the potential of future experimentation at HERA.
A search for the leptonic decays of W bosons produced in the reaction e + p → e + W ± X at a cent... more A search for the leptonic decays of W bosons produced in the reaction e + p → e + W ± X at a centre-of-mass energy of 300 GeV has been performed with the ZEUS detector at HERA using an integrated luminosity of 47.7 pb −1. Three events consistent with W → eν decay are found, giving a cross section estimate of 0.9 +1.0 −0.7 ± 0.2 pb, in good agreement with the Standard Model prediction. The corresponding 95% C.L. upper limit on the cross section is 3.3 pb. A search for the decay W → µν has a smaller selection efficiency and yields no candidate events. Limits on the cross section for W production with large hadronic transverse momentum have been obtained. A search for high-transverse-momentum isolated tracks in events with large missing transverse momentum yields results in good agreement with Standard Model expectations, in contrast to a recent report by the H1 collaboration of the observation of an excess of such events.
Inclusive jet cross sections for events with a large rapidity gap with respect to the proton dire... more Inclusive jet cross sections for events with a large rapidity gap with respect to the proton direction from the reaction ep → jet + X with quasi-real photons have been measured with the ZEUS detector. The cross sections refer to jets with transverse energies E jet
A search for any resonant state coupled to an electron and a proton constituent has been performe... more A search for any resonant state coupled to an electron and a proton constituent has been performed using collisions of electron and proton beams at HERA. In a sample with integrated luminosity of 26 nb-I, no evidence has been found for production of leptoquarks with decays to e-+ jet or v + jet. Limits on the coupling strength of scalar leptoquarks to electron and quark have been determined for masses above 25 GeV. For example, scalar isosinglet leptoquarks (So) with electroweak coupling strength to (e-u) states are ruled out at the 95% confidence level for masses below 168 GeV for left-handed couplings and below 176 GeV for right-handed couplings.
Zeitschrift f�r Physik C Particles and Fields, 1988
The reaction e + e ---&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;µ+µ- has be... more The reaction e + e ---&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;µ+µ- has been studied at centre of mass energies between 35.0 and 46.8 GeV using the TASSO detector at PETRA. We present measurements of the forward-backward charge asymmetry ( A mumu) and cross section sigmamumu for this reaction at three energies. At 35.0 GeV we obtain a cross section relative to the QED prediction of
New experimental data on r'p-Bpr" at 1610 MeV has been analyzed within the framework of the isoba... more New experimental data on r'p-Bpr" at 1610 MeV has been analyzed within the framework of the isobar model. The partial wave amplitudes obtained from this single energy fit have been compared with the smooth K-matrix fits to the two continuous solutions obtained in a previous analysis of TN-x~N in the range 1300-2000 MeV. This test affords a clear choice between the two competing solutions: the 1973 Solution B is the best description of inelastic 7rN scattering at these energies.
Two photon annihilation processes were observed with the TASSO detector at the e+e- storage ring ... more Two photon annihilation processes were observed with the TASSO detector at the e+e- storage ring PETRA. We report on the analyses of untagged and single tag events.
We present high statistics data on differential cross sections and density matrix elements for K*... more We present high statistics data on differential cross sections and density matrix elements for K**(890) production obtained in a 13 GeV/c SLAC experiment. The most remarkable features of the data are the dominance of natural parity exchange and significant differences between K*+ and K*-production by natural parity isoscalar exchange. We present two exchange models which successfully describe this difference, as well as the overall t-dependence: model A including Pomeron plus strongly exchange degenerate Regge poles and model B involving broken exchange degeneracy for the f and w exchanges. These two phenomenological models lead to different predictions for the energy dependence of K** production, for the relative K*(1420)/K* production rate, and for the SU(3) related of production processes.
... 3. Expression of Interest for a "BEAM-DUMP" upgrade of L3 for the LHC (LHCC 95-17 a... more ... 3. Expression of Interest for a "BEAM-DUMP" upgrade of L3 for the LHC (LHCC 95-17 and addendum LHCC 95-22; P.Fisher, J.Kirkby). ... HGFischer, G.Hall, J.Harvey, HJHilke, G.Kellner, U.Koetz, P.Lazeyras, I.Lehraus, M.Mazzucato, R.Mount, M.Mur, E.Petrolo, S.Quinton, W.Smith ...
... range systems for calorimetry. Status Reports of approved projects presented at the open sess... more ... range systems for calorimetry. Status Reports of approved projects presented at the open session. RD-29 A mixed analog-digital radiation hard technology for high energy physics applications (LHCC 95-13). F.Bourgeois gave an ...
ABSTRACT Starting with partial-wave amplitudes for πN--&gt;Nπ and πN--&gt;several isobar-... more ABSTRACT Starting with partial-wave amplitudes for πN--&gt;Nπ and πN--&gt;several isobar-model states of Nππ, we are able to apply the constraint of unitarity (using the K matrix). This permits the removal of the overall phase ambiguity of the isobar amplitudes at each energy. The K-matrix fits generate a smooth prescription for the T-matrix amplitudes, enabling us to search the complex energy plane for poles. The uniqueness of these poles is demonstrated by doing Breit-Wigner refits to the fitted T-matrix amplitudes. The success of the refits and the obvious interpretation justifies a simple determination of coupling signs for which there can be checks with theory.
The exclusive production of ρ^0 mesons in deep inelastic electron-proton scattering has been stud... more The exclusive production of ρ^0 mesons in deep inelastic electron-proton scattering has been studied using the ZEUS detector. Cross sections have been measured in the range 7 < Q^2 < 25 GeV^2 for γ^*p centre of mass (c.m.) energies from 40 to 130 GeV. The γ^*p →ρ^0 p cross section exhibits a Q^-(4.2 ± 0.8 ^+1.4_-0.5) dependence and both longitudinally and transversely polarised ρ^0's are observed. The γ^*p →ρ^0 p cross section rises strongly with increasing c.m. energy, when compared with NMC data at lower energy, which cannot be explained by production through soft pomeron exchange. The data are compared with perturbative QCD calculations where the rise in the cross section reflects the increase in the gluon density at low x. the gluon density at low x.
A high luminosity upgrade of HERA will allow the measurement of standard model parameters and the... more A high luminosity upgrade of HERA will allow the measurement of standard model parameters and the neutral current couplings of quarks. These results will have to be consistent with other precision measurements or indicate traces of new physics. The analysis of W production will complement future results of LEP 2 and the Tevatron. We summarize the main results and conclusions obtained by the working group on Electroweak Physics concerning the potential of future experimentation at HERA.
A search for the leptonic decays of W bosons produced in the reaction e + p → e + W ± X at a cent... more A search for the leptonic decays of W bosons produced in the reaction e + p → e + W ± X at a centre-of-mass energy of 300 GeV has been performed with the ZEUS detector at HERA using an integrated luminosity of 47.7 pb −1. Three events consistent with W → eν decay are found, giving a cross section estimate of 0.9 +1.0 −0.7 ± 0.2 pb, in good agreement with the Standard Model prediction. The corresponding 95% C.L. upper limit on the cross section is 3.3 pb. A search for the decay W → µν has a smaller selection efficiency and yields no candidate events. Limits on the cross section for W production with large hadronic transverse momentum have been obtained. A search for high-transverse-momentum isolated tracks in events with large missing transverse momentum yields results in good agreement with Standard Model expectations, in contrast to a recent report by the H1 collaboration of the observation of an excess of such events.
Inclusive jet cross sections for events with a large rapidity gap with respect to the proton dire... more Inclusive jet cross sections for events with a large rapidity gap with respect to the proton direction from the reaction ep → jet + X with quasi-real photons have been measured with the ZEUS detector. The cross sections refer to jets with transverse energies E jet
A search for any resonant state coupled to an electron and a proton constituent has been performe... more A search for any resonant state coupled to an electron and a proton constituent has been performed using collisions of electron and proton beams at HERA. In a sample with integrated luminosity of 26 nb-I, no evidence has been found for production of leptoquarks with decays to e-+ jet or v + jet. Limits on the coupling strength of scalar leptoquarks to electron and quark have been determined for masses above 25 GeV. For example, scalar isosinglet leptoquarks (So) with electroweak coupling strength to (e-u) states are ruled out at the 95% confidence level for masses below 168 GeV for left-handed couplings and below 176 GeV for right-handed couplings.
Zeitschrift f�r Physik C Particles and Fields, 1988
The reaction e + e ---&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;µ+µ- has be... more The reaction e + e ---&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;µ+µ- has been studied at centre of mass energies between 35.0 and 46.8 GeV using the TASSO detector at PETRA. We present measurements of the forward-backward charge asymmetry ( A mumu) and cross section sigmamumu for this reaction at three energies. At 35.0 GeV we obtain a cross section relative to the QED prediction of
New experimental data on r'p-Bpr" at 1610 MeV has been analyzed within the framework of the isoba... more New experimental data on r'p-Bpr" at 1610 MeV has been analyzed within the framework of the isobar model. The partial wave amplitudes obtained from this single energy fit have been compared with the smooth K-matrix fits to the two continuous solutions obtained in a previous analysis of TN-x~N in the range 1300-2000 MeV. This test affords a clear choice between the two competing solutions: the 1973 Solution B is the best description of inelastic 7rN scattering at these energies.
Two photon annihilation processes were observed with the TASSO detector at the e+e- storage ring ... more Two photon annihilation processes were observed with the TASSO detector at the e+e- storage ring PETRA. We report on the analyses of untagged and single tag events.
We present high statistics data on differential cross sections and density matrix elements for K*... more We present high statistics data on differential cross sections and density matrix elements for K**(890) production obtained in a 13 GeV/c SLAC experiment. The most remarkable features of the data are the dominance of natural parity exchange and significant differences between K*+ and K*-production by natural parity isoscalar exchange. We present two exchange models which successfully describe this difference, as well as the overall t-dependence: model A including Pomeron plus strongly exchange degenerate Regge poles and model B involving broken exchange degeneracy for the f and w exchanges. These two phenomenological models lead to different predictions for the energy dependence of K** production, for the relative K*(1420)/K* production rate, and for the SU(3) related of production processes.
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Papers by R. Cashmore