B radiative decays at LHCb: measurement of B→ K∗γ isospin asymmetry and preparation of Run 3 analyses
[eng] The Standard Model (ME) of particle physics is the theory that describes fundamental particles and their interactions, except gravity. Despite its success and accuracy in predicting phenomena, it is known that it is not a complete theory. It does not describe dark matter or energy, the asymmet...
| Autor: | |
|---|---|
| Tipo de recurso: | tesis doctoral |
| Estado: | Versión publicada |
| Fecha de publicación: | 2025 |
| País: | España |
| Institución: | Universidad de Barcelona |
| Repositorio: | Dipòsit Digital de la UB |
| OAI Identifier: | oai:diposit.ub.edu:2445/226472 |
| Acceso en línea: | https://hdl.handle.net/2445/226472 http://hdl.handle.net/10803/696483 |
| Access Level: | acceso abierto |
| Palabra clave: | Física de partícules Acceleradors de partícules Gran Col·lisionador d'Hadrons Partícules (Matèria) Particle physics Particle accelerators Large Hadron Collider (France and Switzerland) Particles |
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B radiative decays at LHCb: measurement of B→ K∗γ isospin asymmetry and preparation of Run 3 analyses |
| title |
B radiative decays at LHCb: measurement of B→ K∗γ isospin asymmetry and preparation of Run 3 analyses |
| spellingShingle |
B radiative decays at LHCb: measurement of B→ K∗γ isospin asymmetry and preparation of Run 3 analyses Lobo Salvia, Aniol Física de partícules Acceleradors de partícules Gran Col·lisionador d'Hadrons Partícules (Matèria) Particle physics Particle accelerators Large Hadron Collider (France and Switzerland) Particles |
| title_short |
B radiative decays at LHCb: measurement of B→ K∗γ isospin asymmetry and preparation of Run 3 analyses |
| title_full |
B radiative decays at LHCb: measurement of B→ K∗γ isospin asymmetry and preparation of Run 3 analyses |
| title_fullStr |
B radiative decays at LHCb: measurement of B→ K∗γ isospin asymmetry and preparation of Run 3 analyses |
| title_full_unstemmed |
B radiative decays at LHCb: measurement of B→ K∗γ isospin asymmetry and preparation of Run 3 analyses |
| title_sort |
B radiative decays at LHCb: measurement of B→ K∗γ isospin asymmetry and preparation of Run 3 analyses |
| dc.creator.none.fl_str_mv |
Lobo Salvia, Aniol |
| author |
Lobo Salvia, Aniol |
| author_facet |
Lobo Salvia, Aniol |
| author_role |
author |
| dc.contributor.none.fl_str_mv |
Graugés Pous, Eugeni Marin Benito, Carla Universitat de Barcelona. Facultat de Física |
| dc.subject.none.fl_str_mv |
Física de partícules Acceleradors de partícules Gran Col·lisionador d'Hadrons Partícules (Matèria) Particle physics Particle accelerators Large Hadron Collider (France and Switzerland) Particles |
| topic |
Física de partícules Acceleradors de partícules Gran Col·lisionador d'Hadrons Partícules (Matèria) Particle physics Particle accelerators Large Hadron Collider (France and Switzerland) Particles |
| description |
[eng] The Standard Model (ME) of particle physics is the theory that describes fundamental particles and their interactions, except gravity. Despite its success and accuracy in predicting phenomena, it is known that it is not a complete theory. It does not describe dark matter or energy, the asymmetry between matter and antimatter in the Universe, or the origin of neutrino mass. Consequently, it is vitally important to investigate possible extensions of this model and measure processes that may reveal new physics. An experiment that contributes to this task is the LHCb, one of the four main detectors located in the LHC particle accelerator operated by CERN. His study focuses on high-precision measurements of particles involving heavy quarks b and c. Rare radiative decays of B mesons are an ideal platform to test EM and study its possible extensions. These decays cannot occur through tree diagrams within the description of the ME, but take place through loops in which unknown particles could participate, thus altering the observable quantities. This thesis presents three interconnected topics within the study of rare radiative decays of B mesons: the experiment's calorimeter monitoring tools, the radiative inclusive selections in the trigger system, and the measurement of the isospium asymmetry of the B→K*γ decay. The measurement of the isospium asymmetry of the B→K*γ decay has been done using data from Run 2, which covers the years 2015 to 2018. The other two tasks have been carried out within the framework of Run 3, starting in 2021. Between these two Runs, an ambitious improvement program, called Upgrade I, has made it possible to increase the capacity of the detector. Some of the subdetectors have been completely renewed, the data reading system has been improved to facilitate 40 MHz reading and the hardware phase of the trigger has been dismantled, becoming the first large detector with a completely software-based trigger. This set of improvements has made it possible to increase the instantaneous luminosity at which the detector operates by a factor of five, thus gaining sensitivity and its precision measurements. The monitoring of the calorimeter makes it possible to detect anomalies in the data collection and provides information on the origin of the problem in order to be able to solve it quickly. It has been a critical function during the commissioning period of Run 3, until the system has reached its stable operation. Trigger selections inclusive of radiative processes make it possible to capture events of this type and rule out those that constitute background noise, thus keeping the volume of data stored within the limits of the system. The selections for the new instantaneous high luminosity environment have been optimized and the BDT multivariable method has been used in order to obtain the best possible signal efficiency. Finally, the measurement of the isospy asymmetry of the B→K*γ decay is obtained for the first time with data from the LHCb and with an accuracy comparable to the measurements of other experiments, validating the ME and applying constraints on its possible extensions, in particular extensions of supersymmetry and extra Higgs sectors. |
| publishDate |
2025 |
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2025 |
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info:eu-repo/semantics/doctoralThesis info:eu-repo/semantics/publishedVersion |
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doctoralThesis |
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publishedVersion |
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https://hdl.handle.net/2445/226472 http://hdl.handle.net/10803/696483 |
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https://hdl.handle.net/2445/226472 http://hdl.handle.net/10803/696483 |
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Inglés |
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Inglés |
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cc by-nc-sa (c) Lobo Salvia, Aniol, 2025 http://creativecommons.org/licenses/by-nc-sa/4.0/ info:eu-repo/semantics/openAccess |
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cc by-nc-sa (c) Lobo Salvia, Aniol, 2025 http://creativecommons.org/licenses/by-nc-sa/4.0/ |
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openAccess |
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application/pdf |
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Tesis Doctorals - Facultat - Física reponame:Dipòsit Digital de la UB instname:Universidad de Barcelona |
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Universidad de Barcelona |
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Dipòsit Digital de la UB |
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Dipòsit Digital de la UB |
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1869410624428048384 |
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B radiative decays at LHCb: measurement of B→ K∗γ isospin asymmetry and preparation of Run 3 analysesLobo Salvia, AniolFísica de partículesAcceleradors de partículesGran Col·lisionador d'HadronsPartícules (Matèria)Particle physicsParticle acceleratorsLarge Hadron Collider (France and Switzerland)Particles[eng] The Standard Model (ME) of particle physics is the theory that describes fundamental particles and their interactions, except gravity. Despite its success and accuracy in predicting phenomena, it is known that it is not a complete theory. It does not describe dark matter or energy, the asymmetry between matter and antimatter in the Universe, or the origin of neutrino mass. Consequently, it is vitally important to investigate possible extensions of this model and measure processes that may reveal new physics. An experiment that contributes to this task is the LHCb, one of the four main detectors located in the LHC particle accelerator operated by CERN. His study focuses on high-precision measurements of particles involving heavy quarks b and c. Rare radiative decays of B mesons are an ideal platform to test EM and study its possible extensions. These decays cannot occur through tree diagrams within the description of the ME, but take place through loops in which unknown particles could participate, thus altering the observable quantities. This thesis presents three interconnected topics within the study of rare radiative decays of B mesons: the experiment's calorimeter monitoring tools, the radiative inclusive selections in the trigger system, and the measurement of the isospium asymmetry of the B→K*γ decay. The measurement of the isospium asymmetry of the B→K*γ decay has been done using data from Run 2, which covers the years 2015 to 2018. The other two tasks have been carried out within the framework of Run 3, starting in 2021. Between these two Runs, an ambitious improvement program, called Upgrade I, has made it possible to increase the capacity of the detector. Some of the subdetectors have been completely renewed, the data reading system has been improved to facilitate 40 MHz reading and the hardware phase of the trigger has been dismantled, becoming the first large detector with a completely software-based trigger. This set of improvements has made it possible to increase the instantaneous luminosity at which the detector operates by a factor of five, thus gaining sensitivity and its precision measurements. The monitoring of the calorimeter makes it possible to detect anomalies in the data collection and provides information on the origin of the problem in order to be able to solve it quickly. It has been a critical function during the commissioning period of Run 3, until the system has reached its stable operation. Trigger selections inclusive of radiative processes make it possible to capture events of this type and rule out those that constitute background noise, thus keeping the volume of data stored within the limits of the system. The selections for the new instantaneous high luminosity environment have been optimized and the BDT multivariable method has been used in order to obtain the best possible signal efficiency. Finally, the measurement of the isospy asymmetry of the B→K*γ decay is obtained for the first time with data from the LHCb and with an accuracy comparable to the measurements of other experiments, validating the ME and applying constraints on its possible extensions, in particular extensions of supersymmetry and extra Higgs sectors.[cat] El Model Estàndard (ME) de física de partícules és la teoria que descriu les partícules fonamentals i les seves interaccions, excepte la gravetat. Malgrat el seu èxit i precisió en la predicció de fenòmens, se sap que no és una teoria completa. No descriu la matèria ni l’energia fosques, l’asimetria entre matèria i antimatèria a l’Univers, ni l’origen de la massa dels neutrins. En conseqüència, és de vital importància investigar possibles extensions d’aquest model i mesurar processos que puguin revelar nova física. Un experiment que contribueix en aquesta tasca és el LHCb, un dels quatre principals detectors situats a l’accelerador de partícules LHC operat pel CERN. El seu estudi se centra en mesures d’alta precisió de partícules que involucren quarks pesats b i c. Les desintegracions radiatives rares de mesons B constitueixen una plataforma idònia per posar a prova el ME i estudiar-ne possibles extensions. Aquestes desintegracions no poden ocórrer mitjançant diagrames d’arbre dins de la descripció del ME, sinó que tenen lloc mitjançant bucles en els quals podrien participar partícules desconegudes, alterant així les quantitats observables. Aquesta tesi presenta tres temes interconnectats dins de l’estudi de les desintegracions radiatives rares de mesons B: les eines de monitoratge del calorímetre de l’experiment, les seleccions inclusives radiatives en el sistema de trigger i la mesura de l’asimetria d’isospí de la desintegració B→K*γ. La mesura de l’asimetria d’isospí de la desintegració B→K*γ s’ha fet utilitzant dades del Run 2, que compren els anys 2015 a 2018. Les altres dues tasques s’han fet en el marc del Run 3, amb principi a l’any 2021. Entre aquests dos Runs, un ambiciós programa de millora, batejat Upgrade I, ha permès incrementar la capacitat del detector. Part dels subdetectors han estat completament renovats, el sistema de lectura de dades s’ha millorat per facilitar-ne la lectura 40 MHz i la fase de hardware del trigger ha estat desmantellada, passant a ser el primer gran detector amb un trigger completament basat en software. Aquest conjunt de millores ha permès augmentar la lluminositat instantània a la que opera el detector en un factor cinc, guanyant així sensibilitat el les seves mesures de precisió. El monitoratge del calorímetre permet detectar anomalies en la presa de dades i proporciona informació sobre l’origen del problema per tal de poder-lo solucionar ràpidament. Ha estat una funció crítica durant el període de comissionat del Run 3, fins que el sistema ha arribat al seu funcionament estable. Les seleccions de trigger inclusives de processos radiatius permeten capturar esdeveniments d’aquesta tipologia i descartar aquells que constitueixen soroll de fons, mantenint així el volum de dades emmagatzemat dins dels límits del sistema. S’han optimitzat les seleccions per al nou entorn d’alta lluminositat instantània i s’ha empleat el mètode multivariable BDT per tal d’obtenir la millor eficiència de senyal possible. Finalment, s’obté la mesura de l’asimetria d’isospí de la desintegració B→K*γ per primera vegada amb dades del LHCb i amb una precisió comparable a les mesures d’altres experiments, validant el ME i aplicant restriccions sobre les seves possibles extensions, en particular extensions de supersimetria i de sectors de Higgs extra.Graugés Pous, EugeniMarin Benito, CarlaUniversitat de Barcelona. Facultat de Física2025info:eu-repo/semantics/doctoralThesisinfo:eu-repo/semantics/publishedVersionapplication/pdfhttps://hdl.handle.net/2445/226472http://hdl.handle.net/10803/696483Tesis Doctorals - Facultat - Físicareponame:Dipòsit Digital de la UBinstname:Universidad de BarcelonaIngléscc by-nc-sa (c) Lobo Salvia, Aniol, 2025http://creativecommons.org/licenses/by-nc-sa/4.0/info:eu-repo/semantics/openAccessoai:diposit.ub.edu:2445/2264722026-05-27T06:46:51Z |
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