Oscillations in the elastic high energy amplitude Grafström, P.; Martin, A. D.; Ryskin, M. G.
The European physical journal. C, Particles and fields,
08/2024, Letnik:
84, Številka:
8
Journal Article
Recenzirano
Odprti dostop
We discuss the oscillations in the elastic
pp
differential cross section seen in the TOTEM data at
s
=
13
TeV on the top of the usual smooth behaviour.
Luminosity is a key parameter in any particle collider, and its precise determination has proven particularly challenging at hadron colliders. After introducing the concept of luminosity in its ...multiple incarnations and offering a brief survey of the pp and pp¯ colliders built to date, this article outlines the various methods that have been developed for relative-luminosity monitoring, as well as the complementary approaches considered for establishing an absolute luminosity scale. This is followed by a survey, from both a historical and a technical perspective, of luminosity determination at the ISR, the Spp̄S, the Tevatron, RHIC and the LHC. For each of these, we first delineate the interplay between the experimental context, the specificities of the accelerator, and the precision targets suggested by the physics program. We then detail how the different methods were applied to specific experimental environments and how successfully they meet the precision goals.
We present experimental results giving evidence for the strong reduction—a factor of more than 20—of nuclear-charge changing interactions for 18 TeV In49+ ions channeled through a silicon crystal ...bent to 7.5, 11.9 and 19.8 mrad. A very small fraction of the deflected ions suffer electromagnetic or nuclear interactions leading to proton loss while traversing the 60 mm long crystal, even though its thickness corresponds to about 0.13 nuclear interaction lengths for an amorphous material. By considering the deflected ions only, we show experimentally that the nuclear-charge pickup reaction believed to be induced by virtual photons is a short-range phenomenon.
A strong increase of inclusive nuclear-charge pickup cross sections, forming 83Bi from 158A GeV 82Pb ions, is observed in comparison to similar measurements at 10.6A GeV. From the dependence of these ...cross sections on target atomic number, this increase is attributed to the electromagnetic process of pion production by equivalent photons. The observed cross sections can be reproduced quantitatively using the recently developed RELDIS code.
Production of V0 pairs in the hyperon experiment WA89 Adamovich, M.I.; Alexandrov, Yu.A.; Baranov, S.P. ...
The European physical journal. C, Particles and fields,
12/2007, Letnik:
52, Številka:
4
Journal Article
Recenzirano
Odprti dostop
We present a comprehensive study of the inclusive production of V0V0 pairs (V0=Λ, Λ̄ or KS ) by Σ- and π- of 340 GeV/c momentum and neutrons of 260 GeV/c mean momentum in copper and carbon targets. ...In particular, the dependence of the xF spectra on the combination of beam-particle and produced V0V0 pair is investigated and compared to predictions obtained from PYTHIA and QSGM calculations. The data and these predictions differ in many details, the agreement can at best be termed as qualitative. A signal from decays of the tensor meson f’2(1525) was observed in the KS KS mass distribution and inclusive production cross sections were measured. No signal was found from the double-strange H-dibaryon decaying to ΛΛ.
The direct CP violation parameter Re(ϵ′/ϵ) has been measured from the decay rates of neutral kaons into two pions using the NA48 detector at the CERN SPS. The 2001 running period was devoted to ...collecting additional data under varied conditions compared to earlier years (1997–1999). The new data yield the result: Re(ϵ′/ϵ)=(13.7±3.1)×10−4. Combining this result with that published from the 1997, 98 and 99 data, an overall value of Re(ϵ′/ϵ)=(14.7±2.2)×10−4 is obtained from the NA48 experiment.
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