This report reviews the study of open heavy-flavour and quarkonium production in high-energy hadronic collisions, as tools to investigate fundamental aspects of Quantum Chromodynamics, from the ...proton and nucleus structure at high energy to deconfinement and the properties of the Quark–Gluon Plasma. Emphasis is given to the lessons learnt from LHC Run 1 results, which are reviewed in a global picture with the results from SPS and RHIC at lower energies, as well as to the questions to be addressed in the future. The report covers heavy flavour and quarkonium production in proton–proton, proton–nucleus and nucleus–nucleus collisions. This includes discussion of the effects of hot and cold strongly interacting matter, quarkonium photoproduction in nucleus–nucleus collisions and perspectives on the study of heavy flavour and quarkonium with upgrades of existing experiments and new experiments. The report results from the activity of the SaporeGravis network of the I3 Hadron Physics programme of the European Union 7
th
Framework Programme.
We discuss the various mechanisms potentially at work in hadroproduction of heavy quarkonia in the light of computations of higher-order QCD corrections both in the colour-singlet (CS) and ...colour-octet (CO) channels and the inclusion of the contribution arising from the
s
-channel cut in the CS channel. We also discuss new observables meant to better discriminate between these different mechanisms.
A
bstract
We show that we can reproduce all the features of the bottomonium suppression in both proton-nucleus and nucleus-nucleus collisions at LHC energies in a comover-interaction picture. For ...each collision system, we use the measured
relative
suppression of the excited
ϒ
(2
S
) and
ϒ
(3
S
) states to
ϒ
(1
S
) by ATLAS and CMS to parametrise the scattering cross sections of all
S
- and
P
-wave bottomonia with the comoving particles created during the collisions. In addition to a single nonperturbative parameter, these cross sections depend on the momentum distribution of these comovers which we found to be the same for proton-nucleus and nucleus-nucleus collisions as well as for partonic and hadronic comovers. Moreover, we can also reproduce the
absolute
suppresion rates measured by ALICE, ATLAS, CMS and LHCb when the nuclear modifications of the parton densities are taken into account.
Thrombectomy is currently recommended for eligible patients with stroke who are treated within 6 hours after the onset of symptoms.
We conducted a multicenter, randomized, open-label trial, with ...blinded outcome assessment, of thrombectomy in patients 6 to 16 hours after they were last known to be well and who had remaining ischemic brain tissue that was not yet infarcted. Patients with proximal middle-cerebral-artery or internal-carotid-artery occlusion, an initial infarct size of less than 70 ml, and a ratio of the volume of ischemic tissue on perfusion imaging to infarct volume of 1.8 or more were randomly assigned to endovascular therapy (thrombectomy) plus standard medical therapy (endovascular-therapy group) or standard medical therapy alone (medical-therapy group). The primary outcome was the ordinal score on the modified Rankin scale (range, 0 to 6, with higher scores indicating greater disability) at day 90.
The trial was conducted at 38 U.S. centers and terminated early for efficacy after 182 patients had undergone randomization (92 to the endovascular-therapy group and 90 to the medical-therapy group). Endovascular therapy plus medical therapy, as compared with medical therapy alone, was associated with a favorable shift in the distribution of functional outcomes on the modified Rankin scale at 90 days (odds ratio, 2.77; P<0.001) and a higher percentage of patients who were functionally independent, defined as a score on the modified Rankin scale of 0 to 2 (45% vs. 17%, P<0.001). The 90-day mortality rate was 14% in the endovascular-therapy group and 26% in the medical-therapy group (P=0.05), and there was no significant between-group difference in the frequency of symptomatic intracranial hemorrhage (7% and 4%, respectively; P=0.75) or of serious adverse events (43% and 53%, respectively; P=0.18).
Endovascular thrombectomy for ischemic stroke 6 to 16 hours after a patient was last known to be well plus standard medical therapy resulted in better functional outcomes than standard medical therapy alone among patients with proximal middle-cerebral-artery or internal-carotid-artery occlusion and a region of tissue that was ischemic but not yet infarcted. (Funded by the National Institute of Neurological Disorders and Stroke; DEFUSE 3 ClinicalTrials.gov number, NCT02586415 .).
We outline the many physics opportunities offered by a multi-purpose fixed-target experiment using the proton and lead–ion beams of the LHC extracted by a bent crystal. In a proton run with the LHC ...7 TeV beam, one can analyze pp, pd and pA collisions at center-of-mass energy sNN≃115GeV and even higher using the Fermi motion of the nucleons in a nuclear target. In a lead run with a 2.76 TeV-per-nucleon beam, sNN is as high as 72 GeV. Bent crystals can be used to extract about 5×108 protons/s; the integrated luminosity over a year reaches 0.5 fb−1 on a typical 1 cm long target without nuclear species limitation. We emphasize that such an extraction mode does not alter the performance of the collider experiments at the LHC. By instrumenting the target-rapidity region, gluon and heavy-quark distributions of the proton and the neutron can be accessed at large x and even at x larger than unity in the nuclear case. Single diffractive physics and, for the first time, the large negative-xF domain can be accessed. The nuclear target-species versatility provides a unique opportunity to study nuclear matter versus the features of the hot and dense matter formed in heavy-ion collisions, including the formation of the quark–gluon plasma, which can be studied in PbA collisions over the full range of target-rapidity domain with a large variety of nuclei. The polarization of hydrogen and nuclear targets allows an ambitious spin program, including measurements of the QCD lensing effects which underlie the Sivers single-spin asymmetry, the study of transversity distributions and possibly of polarized parton distributions. We also emphasize the potential offered by pA ultra-peripheral collisions where the nucleus target A is used as a coherent photon source, mimicking photoproduction processes in ep collisions. Finally, we note that W and Z bosons can be produced and detected in a fixed-target experiment and in their threshold domain for the first time, providing new ways to probe the partonic content of the proton and the nucleus.
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
B
-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 at BESIII, the LHC, RHIC, FAIR, the Super Flavor and/or Tau–Charm factories, JLab, the ILC, and beyond. The list of newly found conventional states expanded to include
h
c
(1
P
),
χ
c
2
(2
P
),
, and
η
b
(1
S
). In addition, the unexpected and still-fascinating
X
(3872) has been joined by more than a dozen other charmonium- and bottomonium-like “
XYZ
” states that appear to lie outside the quark model. Many of these still need experimental confirmation. The plethora of new 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
,
, and
bound states have been shown to validate some theoretical approaches to QCD and highlight lack of quantitative success for others. Lattice QCD has grown from a tool with computational possibilities to an industrial-strength effort now dependent more on insight and innovation than pure computational power. New effective field theories for the description of quarkonium in different regimes have been developed and brought to a high degree of sophistication, thus enabling precise and solid theoretical predictions. Many expected decays and transitions have either been measured with precision or for the first time, but the confusing patterns of decays, both above and below open-flavor thresholds, endure and have deepened. 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.
We update the study of the polarisation of J/ψ produced in proton–proton collisions at RHIC at s=200 GeV using the QCD-based Colour-Singlet Model (CSM), including next-to-leading order partonic ...matrix elements from gluon and light quark fusion and leading-order contributions from charm-quark initiated processes. To do so, we also evaluate the corresponding cross section differential in PT which agrees qualitatively with the measurements of PHENIX in the central and forward regions at low PT – for instance below 2 GeV, while emphasising the need for Initial State Radiation (ISR) resummation. At mid PT, we also compare the measurements from PHENIX and STAR with the same evaluation complemented with the dominant αS5 contributions (NNLO⋆). We find a reasonable agreement with the data. Regarding the polarisation, as shown for previous studies at larger s and PT, the polarisation pattern from gluon and light quark fusion in the helicity frame is drastically modified at NLO and is shown to be increasingly longitudinal. The yield from charm-gluon fusion is found to be slightly transversally polarised. Combining both these contributions with a data-driven range for the polarisation of J/ψ from χc, we eventually provide an evaluation of the polarisation of the prompt J/ψ yield which is in a good agreement with the experimental data from PHENIX both in the central and forward regions.
.
Objective. To determine the contribution of classical risk factors to the development of cardiovascular disease (CVD) in patients with heterozygous familial hypercholesterolaemia (FH).
Design. A ...retrospective, multi‐centre, cohort study. Extensive data were collected by scrutinizing medical records and the use of questionnaires. Multivariate Cox regression was used to study the relationship between potential risk factors and the occurrence of CVD.
Setting and subjects. We included 2400 FH patients from 27 Dutch lipid clinics. The diagnosis of FH was based upon the presence of a low‐density lipoprotein receptor mutation or upon strict clinical criteria.
Main outcome measures. Cardiovascular mortality and CVD.
Results. During 112.943 person‐years, 782 (32.6%) patients had had at least one cardiovascular event. Male gender (RR 2.82, 95% CI 2.37–3.36), smoking (RR 1.67, 95% CI 1.40–1.99), hypertension (RR 1.36, 95% CI 1.06–1.75), diabetes mellitus (RR 2.19, 95% CI 1.36–3.54), low HDL‐C (RR 1.37, 95% CI 1.15–1.63) and elevated lipoprotein(a) levels (RR 1.50, 95% CI 1.20–1.79) proved to be independent CVD risk factors. These six risk factors explained 18.7% of the variation in the occurrence of CVD.
Conclusions. Male gender, smoking, hypertension, diabetes mellitus, HDL cholesterol and lipoprotein(a) levels proved to be important risk factors for CVD in FH patients. In addition to the routine instiQJ;tution of statin therapy, controlling these factors needs special attention in the management of this disorder.
Objective To determine the efficacy of statin treatment on risk of coronary heart disease in patients with familial hypercholesterolaemia.Design Cohort study with a mean follow-up of 8.5 ...years.Setting 27 outpatient lipid clinics.Subjects 2146 patients with familial hypercholesterolaemia without prevalent coronary heart disease before 1 January 1990.Main outcome measures Risk of coronary heart disease in treated and “untreated” (delay in starting statin treatment) patients compared with a Cox regression model in which statin use was a time dependent variable.Results In January 1990, 413 (21%) of the patients had started statin treatment, and during follow-up another 1294 patients (66%) started after a mean delay of 4.3 years. Most patients received simvastatin (n=1167, 33 mg daily) or atorvastatin (n=211, 49 mg daily). We observed an overall risk reduction of 76% (hazard ratio 0.24 (95% confidence interval 0.18 to 0.30), P<0.001). In fact, the risk of myocardial infarction in these statin treated patients was not significantly greater than that in an age-matched sample from the general population (hazard ration 1.44 (0.80 to 2.60), P=0.23).Conclusion Lower statin doses than those currently advised reduced the risk of coronary heart disease to a greater extent than anticipated in patients with familial hypercholesterolaemia. With statin treatment, such patients no longer have a risk of myocardial infarction significantly different from that of the general population.
We present predictions for double-quarkonium production in the kinematical region relevant for the proposed fixed-target experiment using the LHC beams (dubbed as AFTER@LHC). These include all ...spin-triplet S-wave charmonium and bottomonium pairs, i.e.ψ(n1S)+ψ(n2S), ψ(n1S)+ϒ(m1S) and ϒ(m1S)+ϒ(m2S) with n1,n2=1,2 and m1,m2=1,2,3. We calculate the contributions from double-parton scatterings and single-parton scatterings. With an integrated luminosity of 20 fb−1 to be collected at AFTER@LHC, we find that the yields for double-charmonium production are large enough for differential distribution measurements. We discuss some differential distributions for J/ψ+J/ψ production, which can help to study the physics of double-parton and single-parton scatterings in a new energy range and which might also be sensitive to double intrinsic cc¯ coalescence at large negative Feynman x.
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