A
bstract
Scaled momentum distributions for the strange hadrons
$ K_{\text{S}}^0 $
and
$ \Lambda /\bar{\Lambda } $
were measured in deep inelastic
ep
scattering with the ZEUS detector at HERA using ...an integrated luminosity of 330 pb
−1
. The evolution of these distributions with the photon virtuality,
Q
2
, was studied in the kinematic region 10
< Q
2
<
40000 GeV
2
and 0
.
001
< x <
0
.
75, where
x
is the Bjorken scaling variable. Clear scaling violations are observed. Predictions based on different approaches to fragmentation were compared to the measurements. Leading-logarithm parton-shower Monte Carlo calculations interfaced to the Lund string fragmentation model describe the data reasonably well in the whole range measured. Next-to-leading-order QCD calculations based on fragmentation functions, FFs, extracted from
e
+
e
−
data alone, fail to describe the measurements. The calculations based on FFs extracted from a global analysis including
e
+
e
−
,
ep
and
pp
data give an improved description. The measurements presented in this paper have the potential to further constrain the FFs of quarks, anti-quarks and gluons yielding
$ K_{\text{S}}^0 $
and
$ \Lambda /\bar{\Lambda } $
strange hadrons.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
High- E T dijet photoproduction at HERA Derrick, M.; Nicholass, D.; Yoshida, R. ...
Physical review. D, Particles, fields, gravitation, and cosmology,
10/2007, Volume:
76, Issue:
7
Journal Article
Peer reviewed
Open access
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CMK, CTK, FMFMET, IJS, NUK, PNG, UM
Diffractive photoproduction of vector mesons, \(\gamma p \to V Y\), where Y is a proton-dissociative system, has been measured in e+p interactions with the ZEUS detector at HERA using an integrated ...luminosity of 25\(\pbi\). The differential cross section, \(d\sigma/d t\), is presented for \(1.2 < -t<12{\rm GeV}^2\), where t is the square of the four-momentum transferred to the vector meson. The data span the range in photon-proton centre-of-mass energy, W, from 80 GeV to 120 GeV. The t distributions are well fit by a power law, \(d\sigma/d t \propto (-t)^{-n}\). The slope of the effective Pomeron trajectory, measured from the W dependence of the \(\rho^0\) and \(\phi\) cross sections in bins of t, is consistent with zero. The ratios \(d\sigma_{\gamma p \to \phi Y}/d t\) to \(d\sigma_{\gamma p \to \rho^0 Y}/d t\) and \(d\sigma_{\gamma p \to J/\psi Y}/d t\) to \(d\sigma_{\gamma p \to \rho^0 Y}/d t\) increase with increasing -t. Decay-angle analyses for \(\rho^0\), \(\phi\) and \(J/\psi\) mesons have been carried out. For the \(\rho^0\) and \(\phi\) mesons, contributions from single and double helicity flip are observed. The results are compared to expectations of theoretical models.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Separation of [formula omitted] showers at high energies Grunhaus, J; Kananov, S
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
6/1997, Volume:
391, Issue:
2
Journal Article
Peer reviewed
Open access
We have designed and carried out simulation studies of a two-layer Shower Maximum Detector diagonally off-set (SMD-dos) optimized for the separation of
π
0 showers from γ showers in the 30–150 GeV ...energy range. For 90% γ acceptance the SMD-dos yields
π
0 rejection efficiencies of 92 ± 4%, 87 ± 4% and 32 ± 2%, respectively, for 30, 50 and 150 GeV incident energies. We find that the two-layer SMD-dos is superior to a conventional geometry two-layer Shower Maximum Detector (SMD), of equal granularity, by an average factor of ∼1.5 over the 50–150 GeV energy range.
We also find the interesting result that the two-layer SMD-dos is superior to a higher granularity one-layer SMD which uses the same number of channels.
At hadron-hadron colliders the signature of choice for the detection of the Higgs particle, in the mass range of 120–160 GeV, is via the decay H →
γγ. The addition of a SMD-dos to the planned detectors at the LHC would significantly reduce the background to the γ signal coming from prolific
π
0 production.
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IJS, IMTLJ, KILJ, KISLJ, NUK, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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