Higher order corrections to Semi-Inclusive Hadron Production Processes

In the following pages I am going to present the main results of my PhD research activity. The main focus of my work has been directed towards the improvement of the precision in calculations relevant for understanding the structure of hadrons. More specifically, in the published papers presented in this thesis, we have mainly considered processes with identified hadrons in the final state. Our studies rely on the well established framework of perturbative Quantum Chromodynamics (pQCD) and, as such, are of interest for the description of high energy experiments involving particles interacting through means of the strong force. In this framework, factorization theorems guarantee that in most processes involving hadrons the low energy (non-perturbative) part at which hadrons are observed and the high energy (perturbative) one where particles interact strongly with each others can be formally separated in their theoretical description. The first can be described by universal non perturbative functions which are extracted from fits of global data, whereas the second can be in principle calculated analytically with perturbative techniques. As it can be inferred, the applicability of this framework is strongly correlated to the precision of both the perturbative and the non-perturbative part. Extending their accuracy directly translates on one side into a better description of ob- servables in the already studied kinematic regions of the phase space whereas on the other into an improved prediction power in the extreme kinematic regions where the reliability of the framework itself starts to be questionable at the previously given precision. Due to the perturbative nature of the framework, a way of improving a theoretical calculation is to advance in the perturbative series and to include higher orders in the fixed order expansion, where the expansion parameter considered is the strong coupling constant. This has been our approach, for example, in order to improve the precision of fragmentation functions. They describe the fragmentation of a particle into the observed final sate hadron and have been previously extracted via a global analysis performed at most up to a next-to-leading order accuracy. We have considered next-to-next-to-leading order corrections to the single-inclusive electron-positron annihilation and presented a first fit of fragmentation functions at this accuracy. In another study, we have performed a first calculation of new contributions to the longitudinal structure function of the semi-inclusive deep inelastic scattering. They appear for the first time at next-to-next-leading order and were calculated as a first step toward a complete calculation for this process at this accuracy. A different strategy to advance the precision of perturbative calculations is through the means of resummation techniques. Recurring structures in the perturbative series related with determined kinematical configurations can be “resummed” to all orders. We have considered two different type of resummations. On one side, we have studied the effects of small-z resummations in our already mentioned fragmentation functions’ fit. They affect the extreme low momentum fraction z region, i.e. where the observed hadron carries a small fraction of the fragmenting particle momentum. On the other end, we have included “threshold resummation” in the description of the polarized semi-inclusive deep inelastic scattering. This type of resummation addresses the so called “threshold logarithms” which are connected with the presence of soft gluon emissions. In a further work we have also studied the interplay between the corrections to the fixed order calculation coming from “threshold resummation” and a more kinematical type of corrections generated by the presence of a hadron mass. It is in fact a good approximation to consider hadrons as massless particles for most processes since the scales of energies at which experiments are carried out are usually big enough. There are however cases in which this approximation can not be considered trustworthy for a good description of data. When including the mass of the hadrons in processes such as single-inclusive electron-positron annihilation or deep inelastic scattering, one has to also carefully consider the possible entangled game between different type of corrections affecting the same kinematical regions. This is what we have observed, for example, in the high momentum fraction region for the deep inelastic process when considering both “threshold resummation” and hadron mass effects.Auf den folgenden Seiten werde ich die wichtigsten Ergebnisse meiner Promotionsforschung vorstellen. Der Schwerpunkt meiner Arbeit liegt auf der Verbesserung der Präzision für Berech nungen, die für das Verständnis der Struktur von Hadronen relevant sind. In den veröffentlichten Arbeiten, die in dieser Promotionsarbeit vorgestellt werden, haben wir vor allem Prozesse mit identifizierten Hadronen im Endzustand betrachtet. Unsere Studien beruhen auf dem bewährten Rahmen der perturbativen Quantenchromodynamik (pQCD) und sind daher relevant für die Beschreibung von hochenergetischen Experimenten von Teilchen die der starke Wechselwirkung unterliegen. In diesem Rahmen stellen Faktorisierungstheoreme sicher, dass in Prozessen mit Hadronen der niederenergetische (nicht-perturbative) Anteil und der hochenergetische (perturbative) An teil der Wechselwirkung zwischen den Teilchen in der theoretischen Beschreibung formal getrennt werden können. Der erste Teil kann durch universelle, nicht-perturbative Funktionen beschrieben werden, die in globalen Analysen von Daten extrahiert werden, während der zweite grundsätzlich (analytisch) mit perturbativen Techniken berechnet werden kann. Daher ist die Anwendbarkeit dieser Herangehensweise stark mit der Präzision sowohl des perturbativen als auch des nicht-perturbativen Anteils verbunden. Die Verbesserung der Genauigkeit verursacht auf der einen Seite eine bessere Beschreibung von Wirkungsquerschnitten in bereits untersuchten kinematischen Regionen des Phasenraums, während auf der anderen Seite eine verbesserte Vorhersagekraft in extremen kinematischen Bereichen erreicht werden kann, in denen die Prä zision bisheriger Rechnungen nicht ausreichend ist. Aufgrund der perturbativen Herangehensweise, liegt eine Möglichkeit die theoretische Berechnung zu verbessern darin höhere Beiträge der perturbativen Entwicklung mit einzubeziehen. Dies ist zum Beispiel unser Ansatz, um die Präzision der Fragmentationsfunktionen zu verbessern. Sie beschreiben die Fragmentation eines hochenergetischen Teilchens in ein beobachtetes Hadron und wurden zuvor über eine globale Analysen extrahiert, die bislang bis zu einer “next- to leading order” Genauigkeit durchgeführt wurden. Wir haben “next-to-next-to leading order” Korrekturen für die Elektron-Positron-Annihilation mit einbezogen und eine erste Analyse von Fragmentationsfunktionen für diese Genauigkeit durchgeführt. In einer anderen Studie haben wir eine erste Berechnung der neuen Beiträge zur longitudinalen Strukturfunktion der semi-inklusiven tief inelastischen Streuung durchgeführt. Diese Beiträge kommen zum ersten Mal in der “next-to-next-to leading order” der Störungsreihe vor und wurden als ersten Schritt zu einer vollständigen Berechnung für diesen Prozess bei dieser Genauigkeit berechnet. Eine andere Strategie, um die Präzision der perturbativen Berechnungen voranzutreiben, ist die Anwendung von Resummations Techniken. Wiederkehrende Strukturen in der Störungsreihe, die mit bestimmten kinematischen Konfigurationen verknüpft sind, können zu allen Ordnungen "wieder aufsummiert"werden. Wir haben zwei verschiedene Arten von Resummationen betrachtet. Auf der einen Seite haben wir die Effekte von small-z Resummation in unseren bereits erwähnten Fragmentationsfunktionen berücksichtigt. Sie beeinflussen den kinematischen Bereich von extrem kleinen Impulsbruchteilen z. Das heisst, dass das beobachtete Hadron nur einen kleinen Bruchteil des Impulses des fragmentierenden Teilchens hat. Auf der anderen Seite haben wir für die polarisierte semi-inklusive tief inelastische Streuung “threshold Resummation” berechnet. Diese Art der Resummation betrifft die sogenannten threshold” Logarithmen, die mit der Abstrahlung von weichen Gluonen verbunden sind. In einer weiteren Arbeit haben wir auch das Zusammenspiel zwischen threshold Resummation und Korrekturen aufgrund der Massen von Hadronen analysiert. Es ist in der Tat eine gute Annäherung für die meisten Prozesse, Hadronen als masselose Teilchen zu betrachten, da die Energien, bei denen Experimente durchgeführt werden, meist gross genug sind. Es gibt jedoch Fälle, in denen diese Näherung nicht ausreichend ist um eine gute Beschreibung der Daten zu bekommen. Wenn man die Masse der Hadronen in Prozessen mit beruücksichtigt, wie z. B. für Elektron-Positron-Annihilation oder tief inelastische Streuung, muss man auch den möglichen Einfluss von verschiedenen Korrekturen betrachten, die dieselbe Kinematik beeinflussen. Dies haben wir am Beispiel tief inelastischer Prozesse beobachtet, wenn man gleichzeitig threshold Resummationäls auch Hadronen Massen Effekte berücksichtigt

The SIB Swiss Institute of Bioinformatics' resources: focus on curated databases

The SIB Swiss Institute of Bioinformatics (www.isb-sib.ch) provides world-class bioinformatics databases, software tools, services and training to the international life science community in academia and industry. These solutions allow life scientists to turn the exponentially growing amount of data into knowledge. Here, we provide an overview of SIB's resources and competence areas, with a strong focus on curated databases and SIB's most popular and widely used resources. In particular, SIB's Bioinformatics resource portal ExPASy features over 150 resources, including UniProtKB/Swiss-Prot, ENZYME, PROSITE, neXtProt, STRING, UniCarbKB, SugarBindDB, SwissRegulon, EPD, arrayMap, Bgee, SWISS-MODEL Repository, OMA, OrthoDB and other databases, which are briefly described in this article

A multi-element psychosocial intervention for early psychosis (GET UP PIANO TRIAL) conducted in a catchment area of 10 million inhabitants: study protocol for a pragmatic cluster randomized controlled trial

Multi-element interventions for first-episode psychosis (FEP) are promising, but have mostly been conducted in non-epidemiologically representative samples, thereby raising the risk of underestimating the complexities involved in treating FEP in 'real-world' services

CEPC Technical Design Report -- Accelerator

International audienceThe Circular Electron Positron Collider (CEPC) is a large scientific project initiated and hosted by China, fostered through extensive collaboration with international partners. The complex comprises four accelerators: a 30 GeV Linac, a 1.1 GeV Damping Ring, a Booster capable of achieving energies up to 180 GeV, and a Collider operating at varying energy modes (Z, W, H, and ttbar). The Linac and Damping Ring are situated on the surface, while the Booster and Collider are housed in a 100 km circumference underground tunnel, strategically accommodating future expansion with provisions for a Super Proton Proton Collider (SPPC). The CEPC primarily serves as a Higgs factory. In its baseline design with synchrotron radiation (SR) power of 30 MW per beam, it can achieve a luminosity of 5e34 /cm^2/s^1, resulting in an integrated luminosity of 13 /ab for two interaction points over a decade, producing 2.6 million Higgs bosons. Increasing the SR power to 50 MW per beam expands the CEPC's capability to generate 4.3 million Higgs bosons, facilitating precise measurements of Higgs coupling at sub-percent levels, exceeding the precision expected from the HL-LHC by an order of magnitude. This Technical Design Report (TDR) follows the Preliminary Conceptual Design Report (Pre-CDR, 2015) and the Conceptual Design Report (CDR, 2018), comprehensively detailing the machine's layout and performance, physical design and analysis, technical systems design, R&D and prototyping efforts, and associated civil engineering aspects. Additionally, it includes a cost estimate and a preliminary construction timeline, establishing a framework for forthcoming engineering design phase and site selection procedures. Construction is anticipated to begin around 2027-2028, pending government approval, with an estimated duration of 8 years. The commencement of experiments could potentially initiate in the mid-2030s

CEPC Technical Design Report -- Accelerator

International audienceThe Circular Electron Positron Collider (CEPC) is a large scientific project initiated and hosted by China, fostered through extensive collaboration with international partners. The complex comprises four accelerators: a 30 GeV Linac, a 1.1 GeV Damping Ring, a Booster capable of achieving energies up to 180 GeV, and a Collider operating at varying energy modes (Z, W, H, and ttbar). The Linac and Damping Ring are situated on the surface, while the Booster and Collider are housed in a 100 km circumference underground tunnel, strategically accommodating future expansion with provisions for a Super Proton Proton Collider (SPPC). The CEPC primarily serves as a Higgs factory. In its baseline design with synchrotron radiation (SR) power of 30 MW per beam, it can achieve a luminosity of 5e34 /cm^2/s^1, resulting in an integrated luminosity of 13 /ab for two interaction points over a decade, producing 2.6 million Higgs bosons. Increasing the SR power to 50 MW per beam expands the CEPC's capability to generate 4.3 million Higgs bosons, facilitating precise measurements of Higgs coupling at sub-percent levels, exceeding the precision expected from the HL-LHC by an order of magnitude. This Technical Design Report (TDR) follows the Preliminary Conceptual Design Report (Pre-CDR, 2015) and the Conceptual Design Report (CDR, 2018), comprehensively detailing the machine's layout and performance, physical design and analysis, technical systems design, R&D and prototyping efforts, and associated civil engineering aspects. Additionally, it includes a cost estimate and a preliminary construction timeline, establishing a framework for forthcoming engineering design phase and site selection procedures. Construction is anticipated to begin around 2027-2028, pending government approval, with an estimated duration of 8 years. The commencement of experiments could potentially initiate in the mid-2030s

CEPC Technical Design Report -- Accelerator

International audienceThe Circular Electron Positron Collider (CEPC) is a large scientific project initiated and hosted by China, fostered through extensive collaboration with international partners. The complex comprises four accelerators: a 30 GeV Linac, a 1.1 GeV Damping Ring, a Booster capable of achieving energies up to 180 GeV, and a Collider operating at varying energy modes (Z, W, H, and ttbar). The Linac and Damping Ring are situated on the surface, while the Booster and Collider are housed in a 100 km circumference underground tunnel, strategically accommodating future expansion with provisions for a Super Proton Proton Collider (SPPC). The CEPC primarily serves as a Higgs factory. In its baseline design with synchrotron radiation (SR) power of 30 MW per beam, it can achieve a luminosity of 5e34 /cm^2/s^1, resulting in an integrated luminosity of 13 /ab for two interaction points over a decade, producing 2.6 million Higgs bosons. Increasing the SR power to 50 MW per beam expands the CEPC's capability to generate 4.3 million Higgs bosons, facilitating precise measurements of Higgs coupling at sub-percent levels, exceeding the precision expected from the HL-LHC by an order of magnitude. This Technical Design Report (TDR) follows the Preliminary Conceptual Design Report (Pre-CDR, 2015) and the Conceptual Design Report (CDR, 2018), comprehensively detailing the machine's layout and performance, physical design and analysis, technical systems design, R&D and prototyping efforts, and associated civil engineering aspects. Additionally, it includes a cost estimate and a preliminary construction timeline, establishing a framework for forthcoming engineering design phase and site selection procedures. Construction is anticipated to begin around 2027-2028, pending government approval, with an estimated duration of 8 years. The commencement of experiments could potentially initiate in the mid-2030s

CEPC Technical Design Report -- Accelerator

The Circular Electron Positron Collider (CEPC) is a large scientific project initiated and hosted by China, fostered through extensive collaboration with international partners. The complex comprises four accelerators: a 30 GeV Linac, a 1.1 GeV Damping Ring, a Booster capable of achieving energies up to 180 GeV, and a Collider operating at varying energy modes (Z, W, H, and ttbar). The Linac and Damping Ring are situated on the surface, while the Booster and Collider are housed in a 100 km circumference underground tunnel, strategically accommodating future expansion with provisions for a Super Proton Proton Collider (SPPC). The CEPC primarily serves as a Higgs factory. In its baseline design with synchrotron radiation (SR) power of 30 MW per beam, it can achieve a luminosity of 5e34 /cm^2/s^1, resulting in an integrated luminosity of 13 /ab for two interaction points over a decade, producing 2.6 million Higgs bosons. Increasing the SR power to 50 MW per beam expands the CEPC's capability to generate 4.3 million Higgs bosons, facilitating precise measurements of Higgs coupling at sub-percent levels, exceeding the precision expected from the HL-LHC by an order of magnitude. This Technical Design Report (TDR) follows the Preliminary Conceptual Design Report (Pre-CDR, 2015) and the Conceptual Design Report (CDR, 2018), comprehensively detailing the machine's layout and performance, physical design and analysis, technical systems design, R&D and prototyping efforts, and associated civil engineering aspects. Additionally, it includes a cost estimate and a preliminary construction timeline, establishing a framework for forthcoming engineering design phase and site selection procedures. Construction is anticipated to begin around 2027-2028, pending government approval, with an estimated duration of 8 years. The commencement of experiments could potentially initiate in the mid-2030s

CEPC Technical Design Report -- Accelerator

International audienceThe Circular Electron Positron Collider (CEPC) is a large scientific project initiated and hosted by China, fostered through extensive collaboration with international partners. The complex comprises four accelerators: a 30 GeV Linac, a 1.1 GeV Damping Ring, a Booster capable of achieving energies up to 180 GeV, and a Collider operating at varying energy modes (Z, W, H, and ttbar). The Linac and Damping Ring are situated on the surface, while the Booster and Collider are housed in a 100 km circumference underground tunnel, strategically accommodating future expansion with provisions for a Super Proton Proton Collider (SPPC). The CEPC primarily serves as a Higgs factory. In its baseline design with synchrotron radiation (SR) power of 30 MW per beam, it can achieve a luminosity of 5e34 /cm^2/s^1, resulting in an integrated luminosity of 13 /ab for two interaction points over a decade, producing 2.6 million Higgs bosons. Increasing the SR power to 50 MW per beam expands the CEPC's capability to generate 4.3 million Higgs bosons, facilitating precise measurements of Higgs coupling at sub-percent levels, exceeding the precision expected from the HL-LHC by an order of magnitude. This Technical Design Report (TDR) follows the Preliminary Conceptual Design Report (Pre-CDR, 2015) and the Conceptual Design Report (CDR, 2018), comprehensively detailing the machine's layout and performance, physical design and analysis, technical systems design, R&D and prototyping efforts, and associated civil engineering aspects. Additionally, it includes a cost estimate and a preliminary construction timeline, establishing a framework for forthcoming engineering design phase and site selection procedures. Construction is anticipated to begin around 2027-2028, pending government approval, with an estimated duration of 8 years. The commencement of experiments could potentially initiate in the mid-2030s

CEPC Technical Design Report -- Accelerator

International audienceThe Circular Electron Positron Collider (CEPC) is a large scientific project initiated and hosted by China, fostered through extensive collaboration with international partners. The complex comprises four accelerators: a 30 GeV Linac, a 1.1 GeV Damping Ring, a Booster capable of achieving energies up to 180 GeV, and a Collider operating at varying energy modes (Z, W, H, and ttbar). The Linac and Damping Ring are situated on the surface, while the Booster and Collider are housed in a 100 km circumference underground tunnel, strategically accommodating future expansion with provisions for a Super Proton Proton Collider (SPPC). The CEPC primarily serves as a Higgs factory. In its baseline design with synchrotron radiation (SR) power of 30 MW per beam, it can achieve a luminosity of 5e34 /cm^2/s^1, resulting in an integrated luminosity of 13 /ab for two interaction points over a decade, producing 2.6 million Higgs bosons. Increasing the SR power to 50 MW per beam expands the CEPC's capability to generate 4.3 million Higgs bosons, facilitating precise measurements of Higgs coupling at sub-percent levels, exceeding the precision expected from the HL-LHC by an order of magnitude. This Technical Design Report (TDR) follows the Preliminary Conceptual Design Report (Pre-CDR, 2015) and the Conceptual Design Report (CDR, 2018), comprehensively detailing the machine's layout and performance, physical design and analysis, technical systems design, R&D and prototyping efforts, and associated civil engineering aspects. Additionally, it includes a cost estimate and a preliminary construction timeline, establishing a framework for forthcoming engineering design phase and site selection procedures. Construction is anticipated to begin around 2027-2028, pending government approval, with an estimated duration of 8 years. The commencement of experiments could potentially initiate in the mid-2030s