Refine
Document Type
- Preprint (304)
- Article (160)
- Working Paper (2)
Language
- English (466)
Has Fulltext
- yes (466)
Is part of the Bibliography
- no (466)
Keywords
- Heavy Ion Experiments (12)
- Hadron-Hadron scattering (experiments) (8)
- Quark-Gluon Plasma (4)
- Heavy-ion collision (3)
- Jets and Jet Substructure (3)
- Experimental nuclear physics (2)
- Experimental particle physics (2)
- Lepton-Nucleon Scattering (experiments) (2)
- Particle and resonance production (2)
- Analysis and statistical methods (1)
Institute
Measurement of beauty production via non-prompt D⁰ mesons in Pb–Pb
collisions at √sNN = 5.02 TeV
(2023)
The production of non-prompt D0 mesons from beauty-hadron decays was measured at midrapidity (|y|<0.5) in Pb-Pb collisions at a nucleon-nucleon center-of-mass energy of sNN−−−√=5.02 TeV with the ALICE experiment at the LHC. Their nuclear modification factor (RAA), measured for the first time down to pT=1 GeV/c in the 0−10% and 30−50% centrality classes, indicates a significant suppression, up to a factor of about three, for pT>5 GeV/c in the 0−10% central Pb-Pb collisions. The data are described by models that include both collisional and radiative processes in the calculation of beauty-quark energy loss in the quark-gluon plasma, and quark recombination in addition to fragmentation as a hadronisation mechanism. The ratio of the non-prompt to prompt D0-meson RAA is larger than unity for pT>4 GeV/c in the 0−10% central Pb-Pb collisions, as predicted by models in which beauty quarks lose less energy than charm quarks in the quark-gluon plasma because of their larger mass.
Measurement of beauty production via non-prompt D⁰ mesons in Pb–Pb collisions at √sNN = 5.02 TeV
(2022)
The production of non-prompt D0 mesons from beauty-hadron decays was measured at midrapidity (|y|<0.5) in Pb-Pb collisions at a nucleon-nucleon center-of-mass energy of sNN−−−√=5.02 TeV with the ALICE experiment at the LHC. Their nuclear modification factor (RAA), measured for the first time down to pT=1 GeV/c in the 0−10% and 30−50% centrality classes, indicates a significant suppression, up to a factor of about three, for pT>5 GeV/c in the 0−10% central Pb-Pb collisions. The data are described by models that include both collisional and radiative processes in the calculation of beauty-quark energy loss in the quark-gluon plasma, and quark recombination in addition to fragmentation as a hadronization mechanism. The ratio of the non-prompt to prompt D0-meson RAA is larger than unity for pT>4 GeV/c in the 0−10% central Pb-Pb collisions, as predicted by models in which beauty quarks lose less energy than charm quarks in the quark-gluon plasma because of their larger mass.
In particle collider experiments, elementary particle interactions with large momentum transfer produce quarks and gluons (known as partons) whose evolution is governed by the strong force, as described by the theory of quantum chromodynamics (QCD)1. These partons subsequently emit further partons in a process that can be described as a parton shower2, which culminates in the formation of detectable hadrons. Studying the pattern of the parton shower is one of the key experimental tools for testing QCD. This pattern is expected to depend on the mass of the initiating parton, through a phenomenon known as the dead-cone effect, which predicts a suppression of the gluon spectrum emitted by a heavy quark of mass mQ and energy E, within a cone of angular size mQ/E around the emitter3. Previously, a direct observation of the dead-cone effect in QCD had not been possible, owing to the challenge of reconstructing the cascading quarks and gluons from the experimentally accessible hadrons. We report the direct observation of the QCD dead cone by using new iterative declustering techniques4,5 to reconstruct the parton shower of charm quarks. This result confirms a fundamental feature of QCD. Furthermore, the measurement of a dead-cone angle constitutes a direct experimental observation of the non-zero mass of the charm quark, which is a fundamental constant in the standard model of particle physics.
Pursuant to art. 45 of the Solvency II Framework Directive, all insurance undertakings will be obliged to conduct an “Own Risk and Solvency Assessment” (ORSA). ORSA’s relevance is not limited only to the second pillar of Solvency II, where mainly qualitative requirements are to be found. ORSA rather exhibits strong interlinks with the first pillar and its quantitative requirements and may also serve as a trigger for transparency duties which form Solvency II’s third pillar. ORSA may thus be described in some respects as the glue that binds together all three pillars of Solvency II. ORSA is one of the most obvious examples of the supervisory shift from a rules-based to a principles-based approach. As such, ORSA has hitherto been only very roughly defined. Since it is for the undertaking to determine its own specific risk profile and to evaluate whether this risk profile deviates significantly from the assumptions underlying the standard formula, it seems only natural that the supervisor must specify in greater detail what these underlying assumptions are. The most practicable way to do so would be for EIOPA to establish a “standard insurer”, which implies a translation of the assumptions concerning the underlying probability distributions into directly observable characteristics. The creation of the standard insurer would be an important step towards relaxing the insurers’ fear of what ORSA might bring about.
Coming (great) events cast their (long) shadow before. As the financial crisis gave birth to the creation of the European System of Financial Supervision (ESFS), the imminent Brexit now serves as an impulse to rather extensively reorganize it. Pursuant to the preferences of the Commission—as revealed in its draft for a regulation amending the regulations founding the European Supervisory Authorities (ESA)—the supervision (and regulation) of the financial sectors should be further centralized and integrated and additional powers should be given to the ESAs. To a large degree these alterations are intended to adjust the competences of the European Securities and Markets Authority (ESMA) to better meet its new objectives under the Capital Markets Union (“CMU”). In view that an equivalent to the CMU or the Banking Union—in the sense of a European Insurance Union—is not yet on the horizon for the insurance sector (or the occupational pensions sector), one could prima vista take the view that insurance supervision and regulation is once again taken captive by the necessity of regulatory reforms stemming from other financial sectors. However, even if that is partially the case, the outcome of the intended reforms might still be advantageous for the insurance sector and an important step in the right direction. Therefore, it needs to be intensively discussed.
At this stage, some of the most prominent envisioned changes to the structure, tasks and powers of the European Insurance and Occupational Pensions Authority (EIOPA) and their necessity, usefulness or counter-productivity still have to be examined.
Corporate governance is the set of rules, be they legal or self-regulatory, practices and processes pursuant to which an insurance undertaking is administrated. Good corporate governance is not only key to establishing oneself and succeeding in a competitive environment but also to safeguarding the interests of all stakeholders in an insurance undertaking. It is insofar not surprising that mandatory requirements on the administration of insurance undertakings have become rather prolific in recent years, in an attempt by regulators to protect especially policyholders against perceived risks hailing from improperly governed insurance undertakings. In Germany this has been regarded by many undertakings as an overly paternalistic approach of the legislator, especially considering that the German insurance sector has experienced for decades if not centuries a remarkably low number of insolvencies and that German insurers were neither the trigger nor the (especially) endangered actors in the financial crisis commencing in 2007. Notwithstanding the true core of this criticism, that the insurance industry was taken to a certain degree hostage by the shortcomings within the banking sector, the reform of German Insurance Supervisory Law via implementation of the Solvency II-System has brought many advances in the sense of better governance of insurance undertakings and has also brought to light many deficiencies that the administration of some insurance undertakings may have suffered from in the past, which are now more properly addressed.