45 research outputs found
Hadronic and Electromagnetic Interactions of Quarkonia
We examine the hadronic interactions of quarkonia, focusing on the decays
psi(2s)->psi pi pi and upsilon(2s)-> upsilon pi pi. The leading gluonic
operators in the multipole expansion are matched onto the chiral lagrangian
with the coefficients fit to available data, both at tree-level and loop-level
in the chiral expansion. A comparison is made with naive expectations loosely
based on the large- limit of QCD in an effort to determine the reliability
of this limit for other observables, such as the binding of \ps to nuclei.
Crossing symmetry is used to estimate the cross-section for inelastic
\pi\ps\to\pi\pss scattering, potentially relevant for heavy ion collisions.
The radiative decays psi(2s)->psi pi pi gamma and upsilon(2s)-> upsilon pi pi
gamma are determined at tree-level in the chiral lagrangian. Measurement of
such decays will provide a test of the multipole and chiral expansions. We
briefly discuss decays from the upsilon(3s) and also the contribution from
pions to the electromagnetic polarizability of quarkonia.Comment: 20 pages, 11 figures, late
A new measurement of the Collins and Sivers asymmetries on a transversely polarised deuteron target
New high precision measurements of the Collins and Sivers asymmetries of
charged hadrons produced in deep-inelastic scattering of muons on a
transversely polarised 6LiD target are presented. The data were taken in 2003
and 2004 with the COMPASS spectrometer using the muon beam of the CERN SPS at
160 GeV/c. Both the Collins and Sivers asymmetries turn out to be compatible
with zero, within the present statistical errors, which are more than a factor
of 2 smaller than those of the published COMPASS results from the 2002 data.
The final results from the 2002, 2003 and 2004 runs are compared with naive
expectations and with existing model calculations.Comment: 40 pages, 28 figure
Heavy quarkonium: progress, puzzles, and opportunities
A golden age for heavy quarkonium physics dawned a decade ago, initiated by
the confluence of exciting advances in quantum chromodynamics (QCD) and an
explosion of related experimental activity. The early years of this period were
chronicled in the Quarkonium Working Group (QWG) CERN Yellow Report (YR) in
2004, which presented a comprehensive review of the status of the field at that
time and provided specific recommendations for further progress. However, the
broad spectrum of subsequent breakthroughs, surprises, and continuing puzzles
could only be partially anticipated. Since the release of the YR, the BESII
program concluded only to give birth to BESIII; the -factories and CLEO-c
flourished; quarkonium production and polarization measurements at HERA and the
Tevatron matured; and heavy-ion collisions at RHIC have opened a window on the
deconfinement regime. All these experiments leave legacies of quality,
precision, and unsolved mysteries for quarkonium physics, and therefore beg for
continuing investigations. The plethora of newly-found quarkonium-like states
unleashed a flood of theoretical investigations into new forms of matter such
as quark-gluon hybrids, mesonic molecules, and tetraquarks. Measurements of the
spectroscopy, decays, production, and in-medium behavior of c\bar{c}, b\bar{b},
and b\bar{c} bound states have been shown to validate some theoretical
approaches to QCD and highlight lack of quantitative success for others. The
intriguing details of quarkonium suppression in heavy-ion collisions that have
emerged from RHIC have elevated the importance of separating hot- and
cold-nuclear-matter effects in quark-gluon plasma studies. This review
systematically addresses all these matters and concludes by prioritizing
directions for ongoing and future efforts.Comment: 182 pages, 112 figures. Editors: N. Brambilla, S. Eidelman, B. K.
Heltsley, R. Vogt. Section Coordinators: G. T. Bodwin, E. Eichten, A. D.
Frawley, A. B. Meyer, R. E. Mitchell, V. Papadimitriou, P. Petreczky, A. A.
Petrov, P. Robbe, A. Vair
Heavy Flavour Hadro-Production from Fixed-Target to Collider Energies
We review the hadro-production data presently available on open charm and beauty absolute production cross-sections, collected by experiments at CERN, DESY and Fermilab. The published charm production cross-section values are updated, in particular for the "time evolution" of the branching ratios. These measurements are compared to LO pQCD calculations, as a function of the collision energy, using recent parametrisations of the parton distribution functions. We then estimate, including nuclear effects of the parton densities, the charm and beauty production cross-sections relevant for measurements at SPS and RHIC energies, in proton-proton, proton-nucleus and nucleus-nucleus collisions. The calculations are also compared with measurements of single D and B kinematical distributions, and DDbar pair correlations. We finish with two brief comments, concerning the importance of beauty production as a feed-down source of J/psi production, and open charm measurements performed using leptonic decays
Types of deviation and review criteria in pretreatment central quality control of tumor bed boost in medulloblastoma-an analysis of the German Radiotherapy Quality Control Panel in the SIOP PNET5 MB trial
Purpose In Germany, Austria, and Switzerland, pretreatment radiotherapy quality control (RT-QC) for tumor bed boost (TB) in non-metastatic medulloblastoma (MB) was not mandatory but was recommended for patients enrolled in the SIOP PNET5 MB trial between 2014 and 2018. This individual case review (ICR) analysis aimed to evaluate types of deviations in the initial plan proposals and develop uniform review criteria for TB boost. Patients and methods A total of 78 patients were registered in this trial, of whom a subgroup of 65 patients were available for evaluation of the TB treatment plans. Dose uniformity was evaluated according to the definitions of the protocol. Additional RT-QC criteria for standardized review of target contours were elaborated and data evaluated accordingly. Results Of 65 initial TB plan proposals, 27 (41.5%) revealed deviations of target volume delineation. Deviations according to the dose uniformity criteria were present in 14 (21.5%) TB plans. In 25 (38.5%) cases a modification of the RT plan was recommended. Rejection of the TB plans was rather related to unacceptable target volume delineation than to insufficient dose uniformity. Conclusion In this analysis of pretreatment RT-QC, protocol deviations were present in a high proportion of initial TB plan proposals. These findings emphasize the importance of pretreatment RT-QC in clinical trials for MB. Based on these data, a proposal for RT-QC criteria for tumor bed boost in non-metastatic MB was developed
PROSPECTS FOR B-PHYSICS IN THE NEXT DECADE
In these lectures I review what has been learned from studies of b-quark decays, including semileptonic decays (Vub and Vcb), B o −B o mixing and rare B decays. Then a discussion on CP violation follows, which leads to a summary of plans for future experiments and what is expected to be learned from them