Production of exclusive dijets in diffractive deep inelastic Formula omitted scattering has been measured with the ZEUS detector at HERA using an integrated luminosity of 372 pb Formula omitted. The ...measurement was performed for Formula omitted-p centre-of-mass energies in the range Formula omitted and for photon virtualities Formula omitted. Energy flows around the jet axis are presented. The cross section is presented as a function of Formula omitted and Formula omitted, where Formula omitted, x is the Bjorken variable and Formula omitted is the proton fractional longitudinal momentum loss. The angle Formula omitted is defined by the Formula omitted-dijet plane and the Formula omitted- Formula omitted plane in the rest frame of the diffractive final state. The Formula omitted cross section is measured in bins of Formula omitted. The results are compared to predictions from models based on different assumptions about the nature of the diffractive exchange.
A
bstract
The photoproduction of
D
∗±
mesons has been measured with the ZEUS detector at HERA at three different
ep
centre-of-mass energies,
s
, of 318, 251 and 225 GeV. For each data set,
D
∗±
...mesons were required to have transverse momentum,
p
T
D
∗
, and pseudo-rapidity,
η
D
∗
, in the ranges 1
.
9
< p
T
D
∗
<
20 GeV and |
η
D
∗
|
<
1
.
6. The events were required to have a virtuality of the incoming photon,
Q
2
, of less than 1 GeV
2
. The dependence on
s
was studied by normalising to the high-statistics measurement at
s
=
318
GeV. This led to the cancellation of a number of systematic effects both in data and theory. Predictions from next-to-leading-order QCD describe the
s
dependence of the data well.
(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image) Abstract The photoproduction of D ^sup ±^ mesons has been measured with the ZEUS detector at HERA at three different ep ...centre-of-mass energies, ..., of 318, 251 and 225 GeV. For each data set, D ^sup ±^ mesons were required to have transverse momentum, p ^sub T^^sup D^, and pseudo-rapidity, eta ^sup D^, in the ranges 1.9 < p ^sub T^^sup D^ < 20 GeV and |eta ^sup D^| < 1.6. The events were required to have a virtuality of the incoming photon, Q ^sup 2^, of less than 1 GeV^sup 2^. The dependence on ... was studied by normalising to the high-statistics measurement at ... GeV. This led to the cancellation of a number of systematic effects both in data and theory. Predictions from next-to-leading-order QCD describe the ... dependence of the data well.
The exclusive deep inelastic electroproduction of \(\psi(2S)\) and \(J/\psi(1S)\) at an \(ep\) centre-of-mass energy of 317 GeV has been studied with the ZEUS detector at HERA in the kinematic range ...\(2 < Q^2 < 80\) GeV\(^2\), \(30 < W < 210\) GeV and \(|t| < 1\) GeV\(^2\), where \(Q^2\) is the photon virtuality, \(W\) is the photon-proton centre-of-mass energy and \(t\) is the squared four-momentum transfer at the proton vertex. The data for \(2 < Q^2 < 5\) GeV\(^2\) were taken in the HERA I running period and correspond to an integrated luminosity of 114 pb\(^{-1}\). The data for \(5 < Q^2 < 80\) GeV\(^2\) are from both HERA I and HERA II periods and correspond to an integrated luminosity of 468 pb\(^{-1}\). The decay modes analysed were \(\mu^+\mu^-\) and \(J/\psi(1S) \pi^+\pi^-\) for the \(\psi(2S)\) and \(\mu^+\mu^-\) for the \(J/\psi(1S)\). The cross-section ratio \(\sigma_{\psi(2S)}/\sigma_{J/\psi(1S)}\) has been measured as a function of \(Q^2, W\) and \(t\). The results are compared to predictions of QCD-inspired models of exclusive vector-meson production.
The exclusive deep inelastic electroproduction of \(\psi(2S)\) and \(J/\psi(1S)\) at an \(ep\) centre-of-mass energy of 317 GeV has been studied with the ZEUS detector at HERA in the kinematic range ...\(2 < Q^2 < 80\) GeV\(^2\), \(30 < W < 210\) GeV and \(|t| < 1\) GeV\(^2\), where \(Q^2\) is the photon virtuality, \(W\) is the photon-proton centre-of-mass energy and \(t\) is the squared four-momentum transfer at the proton vertex. The data for \(2 < Q^2 < 5\) GeV\(^2\) were taken in the HERA I running period and correspond to an integrated luminosity of 114 pb\(^{-1}\). The data for \(5 < Q^2 < 80\) GeV\(^2\) are from both HERA I and HERA II periods and correspond to an integrated luminosity of 468 pb\(^{-1}\). The decay modes analysed were \(\mu^+\mu^-\) and \(J/\psi(1S) \,\pi^+\pi^-\) for the \(\psi(2S)\) and \(\mu^+\mu^-\) for the \(J/\psi(1S)\). The cross-section ratio \(\sigma_{\psi(2S)}/\sigma_{J/\psi(1S)}\) has been measured as a function of \(Q^2, W\) and \(t\). The results are compared to predictions of QCD-inspired models of exclusive vector-meson production.
Production of exclusive dijets in diffractive deep inelastic \(e^\pm p\) scattering has been measured with the ZEUS detector at HERA using an integrated luminosity of 372 pb\(^{-1}\). The measurement ...was performed for \(\gamma^*-p\) centre-of-mass energies in the range \(90 < W < 250\) GeV and for photon virtualities \(Q^2 > 25\) GeV\(^2\). Energy and transverse-energy flows around the jet axis are presented. The cross section is presented as a function of \(\beta\) and \(\phi\), where \(\beta=x/x_{\rm I\!P}\), \(x\) is the Bjorken variable and \(x_{\rm I\!P}\) is the proton fractional longitudinal momentum loss. The angle \(\phi\) is defined by the \(\gamma^*-\)dijet plane and the \(\gamma^*-e^\pm\) plane in the rest frame of the diffractive final state. The \(\phi\) cross section is measured in bins of \(\beta\). The results are compared to predictions from models based on different assumptions about the nature of the diffractive exchange.
Phys. Rev. D 89, 072007 (2014) The neutral current e+/-p cross section has been measured up to values of
Bjorken x of approximately 1 with the ZEUS detector at HERA using an integrated
luminosity of ...187 inv. pb of e-p and 142 inv. pb of e+p collisions at sqrt(s) =
318GeV. Differential cross sections in x and Q2, the exchanged boson
virtuality, are presented for Q2 geq 725GeV2. An improved reconstruction method
and greatly increased amount of data allows a finer binning in the high-x
region of the neutral current cross section and leads to a measurement with
much improved precision compared to a similar earlier analysis. The
measurements are compared to Standard Model expectations based on a variety of
recent parton distribution functions.
The neutral current ${e}^{±}p$ cross section has been measured up to values of Bjorken $x\cong 1$ with the ZEUS detector at HERA using an integrated luminosity of ...$187\text{}\text{}{\mathrm{pb}}^{-1}$ of ${e}^{-}p$ and $142\text{}\text{}{\mathrm{pb}}^{-1}$ of ${e}^{+}p$ collisions at $\sqrt{s}=318\text{}\text{}\mathrm{GeV}$. Differential cross sections in $x$ and ${Q}^{2}$, the exchanged boson virtuality, are presented for ${Q}^{2}\ge 725\text{}\text{}{\mathrm{GeV}}^{2}$. An improved reconstruction method and greatly increased amount of data allows a finer binning in the high-$x$ region of the neutral current cross section and leads to a measurement with much improved precision compared to a similar earlier analysis. The measurements are compared to Standard Model expectations based on a variety of recent parton distribution functions.
PDF
