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Littérature scientifique sur le sujet « Flavour Universality »

Auteur : Grafiati

Publié le 9 mars 2023

Mis à jour le 10 mars 2023

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Articles de revues sur le sujet "Flavour Universality"

de Simone, P. « Experimental Review on Lepton Universality and Lepton Flavour Violation tests in B decays ». EPJ Web of Conferences 234 (2020) : 01004. http://dx.doi.org/10.1051/epjconf/202023401004.

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Tests of lepton flavour universality in B decays offer an excellent opportunity to test the Standard Model, and show hints of new physics in analyses performed by the LHCb, Belle and BaBar experiments. Several theoretical models proposed to explain possible violation of lepton flavour universality claim a connection with lepton flavour violation in B decays. These proceedings review the experimental status of the tests of lepton flavour universality and the searches of lepton flavour violation in B decays.

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Di Luzio, Luca. « Flavour Violating Axions ». EPJ Web of Conferences 234 (2020) : 01005. http://dx.doi.org/10.1051/epjconf/202023401005.

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I review the physics case for flavour violating axions. In particular, I argue that relaxing the assumption of the universality of the Peccei-Quinn current opens up new pathways, including: the relaxation of the Supernova bound on the axion mass, a possible connection with the Standard Model flavour puzzle and the experimental opportunity of discovering the axion via flavoured axion searches.

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Lupato, Anna. « Tests of Lepton Flavour Universality at LHCb ». International Journal of Modern Physics : Conference Series 46 (janvier 2018) : 1860070. http://dx.doi.org/10.1142/s2010194518600704.

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In the Standard Model the electroweak coupling of the gauge bosons to leptons is independent of the lepton flavour. Semileptonic and rare decays of b quarks provide an ideal laboratory to test this property. Any violation of Lepton Flavour Universality would be a clear sign of physics beyond the Standard Model. In this work a review of the Lepton Flavour Universality tests performed using data collected by the LHCb experiment in 2011 and 2012 at a centre of mass energy of 7 and 8 TeV is presented.

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Müller, Dario. « Leptoquarks in Flavour Physics ». EPJ Web of Conferences 179 (2018) : 01015. http://dx.doi.org/10.1051/epjconf/201817901015.

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While the LHC has not directly observed any new particle so far, experimental results from LHCb, BELLE and BABAR point towards the violation of lepton flavour universality in b ⟶ sℓ+ and b ⟶ c-ℓν. In this context, also the discrepancy in the anomalous magnetic moment of the muon can be interpreted as a sign of lepton flavour universality violation. Here we discuss how these hints for new physics can also be explained by introducing leptoquarks as an extension of the Standard Model. Indeed, leptoquarks are good candidates to explain the anomaly in the anomalous magnetic moment of the muon because of an mg/mμ enhanced contribution giving correlated effects in Z boson decays which is particularly interesting in the light of future precision experiments.

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Müller, Katharina. « Tests of Lepton Flavour Universality at LHCb ». Journal of Physics : Conference Series 1271 (juillet 2019) : 012009. http://dx.doi.org/10.1088/1742-6596/1271/1/012009.

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Paradisi, Paride. « Revisiting Lepton Flavour Universality in B Decays ». Nuclear and Particle Physics Proceedings 285-286 (avril 2017) : 116–21. http://dx.doi.org/10.1016/j.nuclphysbps.2017.03.021.

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Buonaura, A. « Tests of lepton flavour universality at LHCb ». Journal of Physics : Conference Series 1586 (août 2020) : 012031. http://dx.doi.org/10.1088/1742-6596/1586/1/012031.

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Vilain, P., G. Wilquet, R. Beyer, W. Flegel, H. Grote, T. Mouthuy, H. Øveras et al. « Flavour universality of neutrino couplings with the z ». Physics Letters B 320, n^o 1-2 (janvier 1994) : 203–5. http://dx.doi.org/10.1016/0370-2693(94)90846-x.

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Kotov, Andrey Yu, Maria Paola Lombardo et Anton Trunin. « Gliding Down the QCD Transition Line, from Nf = 2 till the Onset of Conformality ». Symmetry 13, n^o 10 (1 octobre 2021) : 1833. http://dx.doi.org/10.3390/sym13101833.

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We review the hot QCD transition with varying number of flavours, from two till the onset of the conformal window. We discuss the universality class for Nf=2, along the critical line for two massless light flavours, and a third flavour whose mass serves as an interpolator between Nf=2 and Nf=3. We identify a possible scaling window for the 3D O(4) universality class transition, and its crossover to a mean field behaviour. We follow the transition from Nf=3 to larger Nf, when it remains of first order, with an increasing coupling strength; we summarise its known properties, including possible cosmological applications as a model for a strong electroweak transition. The first order transition, and its accompanying second order endpoint, finally morphs into the essential singularity at the onset of the conformal window, following the singular behaviour predicted by the functional renormalisation group.

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Lafferty, G. « Pentaquarks and possible anomalies at LHCb ». International Journal of Modern Physics A 31, n^o 20n21 (27 juillet 2016) : 1630032. http://dx.doi.org/10.1142/s0217751x16300325.

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With the LHC Run 1 data, the LHCb experiment discovered two pentaquark states and has evidence for a number of possible anomalies in the flavour sector. The possible anomalies include indications of violations of lepton flavour universality, deviations from Standard Model predictions in several [Formula: see text]-meson decay modes that are mediated by flavour-changing neutral currents, and further evidence for a discrepancy between inclusive and exclusive measurements of the CKM matrix element [Formula: see text].

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Plus de sources

Thèses sur le sujet "Flavour Universality"

Gioventù, Alessandra. « Test of lepton flavour universality with charm semileptonic decays ». Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/15749/.

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L'universalità leptonica è una delle simmetrie del Modello Standard (SM). Essa prevede che l'accoppiamento tra i bosoni di gauge e i leptoni delle tre famiglie sia uguale. I recenti risultati sperimentali sulle transizioni b->clnu , in particolare gli osservabili R(D) e R(D*) mostrano una differenza significativa dai valori previsti dal SM, aprendo le porte alla ricerca di nuova fisica anche nei decadimenti di mesoni charmed, che a livello di quark corrispondo alla transizione c->slnu, dove l può essere un muone o un elettrone. I test dello SM sono studiati attraverso la misura del rapporto R(mu/e), definito come R(mu/e)=(dΓ(μ)/dq2)/(dΓ(e)/dq2). In questa tesi è stato realizzato uno studio preliminare che permette la misura di R(mu/e) attraverso la catena di decadimento D*^+ -> (D^0 → K^−l^+nu)pi^+, utilizzando i dati raccolti da LHCb durante il Run-2. Al fine di ottenere le informazioni complete sui prodotti del decadimento D^0 → K^−l^+nu, inclusa la stima del momento del neutrino, è stato implementato un algoritmo di global fit (GF). Inoltre, è stata studiata la contaminazione dello spettro di massa invariante del D^{*+}, dovuta a diversi canali di fondo. Per estrarre il numero di eventi di segnale, è stato fatto un fit di chi-quadro sulla massa invariante del D^{*+}, considerando soltanto il fondo combinatorio su un campione di dati, filtrato con dei tagli di PID, utili a ridurre altri fondi.

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MELONI, SIMONE. « Test of lepton flavour universality with the simultaneous measurement of R(D+) and R (D*+) with τ→ μνν decays at the LHCb experiment ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2022. http://hdl.handle.net/10281/364128.

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Nel Modello Standard delle interazioni fondamentali l’accoppiamento dei bosoni di gauge ai leptoni è indipendente dal flavour leptonico. Questa proprietà, conosciuta come Universalit di Flavour leptonico, è una simmetria accidentale del modello che pu essere testata in decadimenti semileptonici di mesoni contententi quark di tipo b. Le variabili usate per testare l’Universalità di Flavour leptonico sono rapporti di ratei di decadimento tra transizioni con un leptone τ e transizioni con un leptone μ nello stato finale: R(H c ) = B(B → Hc τ ν) / B(B → Hc μν), con Hc che rappresenta un mesone contenente un quark c prodotto nel decadimento. L’osservazione di qualsiasi segno di deviazione in queste variabili rispetto alle previsioni del Modello Standard potrebbe essere un chiaro segno dell’effetto di effetti di nuova fisica. Combinando le misure dei parameteri R(D) e R(D*) effettuate dalle collaborazioni Belle, BaBar e LHCb, è stata osservata una tensione rispetto alle previsioni del Modello Standard a livello di circa 3σ. Ad oggi nessuna misura del parametro R(D) è mai stata effettuata a collider adronici. Questa tesi riporta una misura simultanea dei parametetri R(D+) e R(D *+) effettuata tramite l’analisi di decadimenti B → D(*)l ν . Questa misura utilizza il decadimento leptonico del τ , τ → μνν, sfruttando un campione di 2.0 /fb di dati raccolto in collisioni protone-protone, ad un’energia nel centro di massa di 13 TeV dall’esperimento LHCb durante la presa dati degli anni 2015 e 2016. Tutti i passi dell’analisi sono stati effettuati e le principali incertezze sistematiche sono state valutate. Il valore dei parametri è ancora blinded e l’analisi è in revisione interna presso la collaborazione LHCb. L’incertezza attesa associata ai parametri di interesse è: R(D + ) = xxx ± 0.033(stat.) ± 0.037(syst.), R(D *+ ) = xxx ± 0.040(stat.) ± 0.070(syst.).
In the Standard Model of particle physics, the coupling of the electroweak gauge bosons to the leptons is independent of the lepton flavour. This property, known as Lepton Flavour Universality, is an accidental symmetry of the Standard Model, which can be tested in semileptonic b-meson decays. The variables used to test the Lepton Flavour Universality hypothesis are ratios of branching fractions between decays with the τ lepton and the ones with the μ lepton in the final state: R(Hc) = B(B → Hc τ ν) / B(B → Hc μν) with Hc a charmed meson produced in the decay. Any sign of deviation with respect to the Standard Model predictions in these variables could be a clear sign of New Physics effects. A tension at the level of 3σ with respect to the Standard Model predictions has been observed in the combination of the measurements of R(D) and R(D*) performed by the Belle, BaBar and LHCb collaborations. At the time of writing of this thesis, no measurement of the R(D) parameter has been performed by any hadron collider experiment. This thesis reports a simultaneous measurement of the R(D+) and R(D*+) parameters performed using B → D(*)lν decays. This measurement exploits leptonic decays of the τ lepton, τ → μνν , using a data sample corresponding to an integrated luminosity of 2.0 /fb collected in proton-proton collisions at a centre-of-mass energy of 13 TeV at the LHCb experiment during the 2015 and 2016 data taking years. All the steps of the analysis have been performed and all the main systematic uncertainties have been studied. The value of the measured parameters is still blinded and the analysis is in internal review within the LHCb collaboration. The expected uncertainty on the parameters of interest is given by R(D+) = xxx ± 0.033(stat.) ± 0.037(syst.), R(D*+)= xxx ± 0.040(stat.) ± 0.070(syst.).

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Moscati, Marta [Verfasser], et U. [Akademischer Betreuer] Nierste. « Lepton Flavour Non-Universality - From Effective Field Theory to Extended Gauge Models / Marta Moscati ; Betreuer : U. Nierste ». Karlsruhe : KIT-Bibliothek, 2019. http://d-nb.info/1202076823/34.

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Daussy-Renaudin, Victor. « Probing Lepton Flavour Universality through semitauonic Λb decays using three-pions τ-lepton decays with the LHCb experiment at CERN ». Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS335/document.

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L'étude de l'universalité de la saveur des leptons est actuellement un sujet prometteur pour tester la présence de contributions de nouvelle physique dans des processus décrits par le Modèle Standard. Les mesures de désintégrations semitauoniques sont particulièrement intéressantes car de possibles couplages de nouvelle physique au lepton τ pourraient être accrus par rapport aux deux autres leptons du fait de sa masse. Les mesures expérimentales des rapports de branchement des désintégrations B->D*τν et B->Dτν sont présentement en tension avec les prédictions théoriques à la hauteur de 3.78σ. De nouvelles mesures ainsi que l'étude de nouveaux canaux sont ainsi indispensables pour comprendre l'origine de ce désaccord. Le travail présenté dans cette thèse décrit l'utilisation d'une nouvelle technique pour reconstruire le lepton τ via sa désintégration en trois pions et son usage pour mesurer des rapports de rapports de branchements pour deux désintégrations B->D*τν et Λb->Λcτν par rapport aux mêmes désintégrations impliquant des muons. Ces rapports sont respectivement dénommés R(D*) et R(Λc). R(D*) est mesuré en utilisant les 3 fb⁻¹ de collisions proton-proton collectées par le détecteur LHCb pendant le Run1 du LHC à une énergie dans le centre de masse de 7 et 8 TeV via la reconstruction du τ en trois pions. Le résultat obtenu R(D*⁻) = 0.291 ± 0.019(stat) ± 0.026(syst) ± 0.013(ext) est compatible avec la prédiction du Modèle Standard à 1σ près tout en étant cohérent avec les mesures précédemment effectuées. Sa précision permet aussi de conforter le désaccord entre la combinaison des mesures et la prédiction théorique. Ces mêmes données sont aussi analysées dans cette thèse afin d'étudier la désintégration Λb->Λcτν observée pour la première fois avec une significance de 5.7σ. Les incertitudes statistiques et systématiques sont aussi estimées et R(Λc) peut s'écrire R(Λc) = X*(1 ± 0.105(stat) ± 0.162(syst) ± 0.12(ext)) avec la valeur centrale encore masquée à ce jour
Probing Lepton Flavour Universality has been recently a very promising topic to test for the presence of New Physics contributions in Standard Model processes. Measurements involving semitauonic decays are interesting as potential New Physics couplings to the τ-lepton could be enhanced with respect to the two other leptons due to its mass. Experimental measurements of B->D*τν and B->Dτν branching fractions are currently in tension with theoretical predictions at the 3.78σ level. Both precise measurements and analyses of new channels are thus required to understand the source of this disagreement. The work presented in this thesis describes the use of a new technique to reconstruct τ-lepton using its decay into three pions and its use to measure ratios of branching fractions for two decays B->D*τν and Λb->Λcτν with respect to the same decays involving a muon, these ratios are referred to as R(D*) and R(Λc). Using the 3 fb⁻¹ of proton-proton collisions recorded by the LHCb detector during the LHC Run1 at a centre-of-mass energy of 7 and 8 TeV, R(D*) was measured using the three-pions reconstruction for the τ to be R(D*⁻) = 0.291 ± 0.019(stat) ± 0.026(syst) ± 0.013(ext) This result is compatible with the Standard Model expectation at the 1σ level and is consistent with previous measurements. Its precision is able to slightly enforce the disagreement between the combination of the measurements with the theoretical prediction. The same dataset is also analysed in this thesis to study the Λb->Λcτν decay which is observed for the first time with a significance of 5.7σ. Both statistical and systematic uncertainties were estimated and R(Λc) can then be expressed as R(Λc) = X*(1 ± 0.105(stat) ± 0.162(syst) ± 0.12(ext)) with its central value remaining blind at the moment

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Betti, Federico <1990&gt. « CP violation in D0→K+K- and D0→π+π- decays and lepton-flavour universality test with the decay B0→D*-τ+ντ ». Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amsdottorato.unibo.it/8769/1/betti_federico_tesi.pdf.

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The LHCb experiment has been designed to exploit the potential of heavy-flavour production in highly energetic pp collisions at the Large Hadron Collider, in order to look for indirect signs of physics beyond the Standard Model of particle physics. This thesis presents two distinct measurements performed using LHCb data. The first is that of the ratio of branching fractions R(D*)=B(B→D*-τ+ντ)/B(B→D*-l+νl), with the τ lepton decaying to final states containing three charged pions, performed using a data sample of pp collisions at the centre-of-mass energies of 7 and 8 Tev, corresponding to 3fb-1 of integrated luminosity. The result is R(D*)=0.291±0.019±0.026±0.013, where the first uncertainty is statistical, the second systematic and the third due to the knowledge of the B(B→D*-π+π-π+) branching fraction, as this decay is used in the analysis as a normalisation for the intermediate measurement of B(B→D*-τ+ντ). This corresponds to one of the most precise single measurements of R(D*) and to the first performed with the three-prong decay of the τ lepton to date. The measured value of R(D*) is compatible with previous determinations and with the Standard Model expectation. The second measurement presented in this thesis is that of the difference between the CP asymmetries in D0→K+K- and D0→π+π- decays, performed using a data sample of pp collisions at the centre-of-mass energy of 13 Tev, corresponding to 6fb-1 of integrated luminosity. The value of ΔACP=ACP(K+K-)-ACP(π+π-), measured by reconstructing D0 mesons which originate from D*+→D0π+ decays or from B→D0μνX decays, is ΔACP=(-17.1±3.0±1.0)x10-4, where the first uncertainty is statistical and the second systematic. By combining this result with previous LHCb measurements based on Run-1 data, the value of ΔACP results to be ΔACP=(-15.4±2.9)x10-4, which differs from zero by 5.3 standard deviations. This is the first observation of CP violation in the decay of a charm hadron.

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Mogini, Andrea. « Search for the Lepton Flavour Violating decay B0 → K∗0τ±μ∓ with the LHCb detector and pattern recognition for the upgrade with the SciFi Tracker ». Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS367.

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Dans cette thèse je présente les résultats d'études sur la performance d'algorithmes dédiés à la reconstruction des trajectoires de particules chargés avec le trajectographe SciFi, qui sera installé dans l'expérience LHCb pendant son upgrade. Les performances augmentent en termes d'efficacité de reconstruction ainsi que de temps de calcul si une ou deux couches de fibres scintillantes additionnelles sont utilisées. Les stratégies de reconstruction alternatives testées sans couches additionnelles permettent d'obtenir un gain en termes de temps de calcul au détriment des efficacités de reconstruction. Je présente aussi la recherche pour la désintégration violant la conservation de la saveur leptonique B0 → K∗0τ±μ∓, en détaillant la sélection employée sur les données et le traitement statistique utilisé pour quantifier la sensibilité de l'analyse et obtenir des valeurs de l'ordre de O(10−5) pour les limites attendues
In this thesis I report the results of performance studies conducted on the pattern recognition algorithm dedicated to the Scintillating Fibre Tracker to be installed in the LHCb detector during its upgrade. The performance increases both in terms of reconstruction efficiencies and in processing time when working with additional scintillating fibre layers. The alternative tracking strategies tested allow for an improvement on the timing end at the cost of the reconstruction efficiencies. I also detail the selection and limit extraction procedure put in place for the search of the Lepton Flavour Violating decay B0 → K∗0τ±μ∓, finding expected limits at the level of I also detail the selection and limit extraction procedure put in place for the search of the Lepton Flavour Violating decay B0 → K∗0τ±μ∓, finding expected limits of O(10−5)

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GIUGLIANO, Carmen. « Test of Lepton Flavour Universality using the B_s^0→D_s^- τ^+ ν_τ with 3 prongs τ^+ decays and validation of the new opto-electronics for the RICH Upgrade at the LHCb experiment ». Doctoral thesis, Università degli studi di Ferrara, 2022. http://hdl.handle.net/11392/2496468.

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The Standard Model (SM) of particle physics assumes that the couplings between leptons and the electroweak gauge bosons are independent of the lepton flavour up to a correction due to the mass. This property is known as Lepton Flavour Universality (LFU). Ideal laboratories to test the LFU are the b-hadron semileptonic decays which can be studied through the ratios of branching fractions between decays with the τ lepton and the ones with the μ lepton in the final state: R(Hc) =B(Hb → Hcτν)/B(Hb → Hcμν), with Hb and Hc the b−hadron which originates the decay and the c−hadron produced in the decay respectively. Experimental results on LFU tests have been obtained by Belle, BaBar and LHCb collaborations and show tension with the SM prediction of about 3.4σ when considering the combination of the measurement of R(D) and R(D∗). Exploiting the abundance of the b-hadron produced in the LHCb environment and the features of the detector, that allow to reconstruct the b-hadron decay vertex with high precision and to perform particle identification, this thesis documents the preliminary studies for the measurement of R(Ds) using the τ decaying in 3 charged pions. The data sample used for the studies corresponds to an integrated luminosity of 2 fb^{−1} of proton-proton collision events at a centre-of-mass energy of 8 TeV collected by the LHCb experiment in 2012. Given the request of high precision measurements to further test the SM in many other sectors, the LHCb experiment is currently being upgraded to be able to operate at a luminosity of about 2×10^33cm^{−2}s^{−1} from the start of Run3 in 2022. To cope with the challenge of a five-fold increased instantaneous luminosity, and the need to read-out the full LHCb detector at a rate of 40 MHz, the photon detectors and the electronics chain of both the Ring Imaging CHerenkov (RICH) detectors have been replaced. This thesis also describes the quality assurance and test protocols on the new opto-electronics and reports of the commissioning activities.
ITA: Il Modello Standard (MS) della fisica delle particelle elementari assume che l’accoppiamento elettrodebole tra i leptoni e i bosoni di gauge sia indipendente dalla famiglia leptonica a meno di correzioni dovute alla massa. Tale proprietà è conosciuta come Universalità Leptonica (Lepton Flavour Universality o LFU). I decadimenti semileptonici di adroni b sono laboratori ideali per testare la LFU attraverso il confronto tra i rapporti di diramazione dei decadimenti nel cui stato finale sono coinvolti un leptone τ o un leptone μ: R(Hc) = B(Hb → Hcτν)/ B(Hb → Hcμν), dove Hb e Hc sono rispettivamente l’adrone b da cui si origina il decadimento e l’adrone c prodotto nel decadimento. Risultati sperimentali su test di LFU sono stati ottenuti dalle collaborazioni Belle, Babar e LHCb e mostrano tensioni con le predizioni del MS di circa 3.4σ quando si considera la combinazione delle misure di R(D) and R(D∗). Questa tesi, sfruttando l’abbondanza di adroni b prodotti in LHCb e le caratteristiche del rivelatore, documenta gli studi preliminari per la misura di R(Ds) richiedendo nello stato finale un leptone τ che decade in 3 pioni carichi. I dati analizzati per questi studi sono stati raccolti da LHCb nel 2012, sono relativi a collisioni protone protone con energia nel centro di massa pari a 8TeV, e corrispondono ad una luminosità integrata di 2 fb^{−1}. Data la richiesta di misure sempre più precise per testare ulteriormente il MS, l’esperimento LHCb è stato sottoposto ad un upgrade per essere in grado di operare alla luminosità di circa 2×10^33cm^{−2}s^{−1} dall’inizio del Run3 nel 2022. Per fronteggiare la sfida di una luminosità istantanea aumentata di cinque volte rispetto al Run2 e alla necessità di acquisire i dati ad una frequenza di 40 MHz, i rivelatori di fotoni e l’intera catena di elettronica di entrambi i sottorivelatori Ring Imaging CHerenkov sono stati sostituiti. Questa tesi descrive, inoltre, i protocolli di controllo qualità, i test effettuati sulla nuova optoelettronica, e le attività di istallazione e messa in opera dei nuovi sottorivelatori.

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Weiland, Cedric. « Effects of fermionic singlet neutrinos on high- and low-energy observables ». Phd thesis, Université Paris Sud - Paris XI, 2013. http://tel.archives-ouvertes.fr/tel-00922999.

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In this doctoral thesis, we study both low- and high-energy observables related to massive neutrinos. Neutrino oscillations have provided indisputable evidence in favour of non-zero neutrino masses and mixings. However, the original formulation of the Standard Model cannot account for these observations, which calls for the introduction of new Physics. Among many possibilities, we focus here on the inverse seesaw, a neutrino mass generation mechanism in which the Standard Model is extended with fermionic gauge singlets. This model offers an attractive alternative to the usual seesaw realisations since it can potentially have natural Yukawa couplings (O(1)) while keeping the new Physics scale at energies within reach of the LHC. Among the many possible effects, this scenario can lead to deviations from lepton flavour universality. We have investigated these signatures and found that the ratios R_K and R_π provide new, additional constraints on the inverse seesaw. We have also considered the embedding of the inverse seesaw in supersymmetric models. This leads to increased rates for various lepton flavour violating processes, due to enhanced contributions from penguin diagrams mediated by the Higgs and Z bosons. Finally, we also found that the new invisible decay channels associated with the sterile neutrinos present in the supersymmetric inverse seesaw could significantly weaken the constraints on the mass and couplings of a light CP-odd Higgs boson.

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Lisovskyi, Vitalii. « Study of rare b-baryon decays and test of lepton universality at LHCb ». Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS208/document.

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Les courants neutres changeant la saveur b -> sl⁺l⁻ ne sont autorisés dans le Modèle Standard (MS) qu'au niveau des boucles.Par conséquent, ils sont sensibles aux éventuels effets de la Nouvelle Physique (NP) au-delà du MS.Dans le MS, les transitions b -> se⁺e⁻ et b -> sμ⁺μ⁻ ont la même probabilité, cette propriété est appelée l'universalité du couplage aux leptons (UL).Tester l'UL dans les désintégrations de hadrons beaux a récemment été un domaine prometteur pour les recherches de NP. Des tensions par rapport aux prédictions du MS, de l'ordre de 2,5 déviations standards, ont été observées dans les désintégrations rares B -> K(*) l⁺l ⁻. À ce jour, les tests de l'UL ont été effectués uniquement sur des désintégrations de mesons beaux.Cette thèse présente un premier test de la UL dans la désintégration rare du baryon Lambdab -> pK l⁺l⁻ , en utilisant les données collectées par l'expérience LHCb au CERN en 2011, 2012 et 2016. La sensibilité statistique attendue est d'environ 15%, tandis que la valeur centrale reste aveuglée.La première mesure du rapport de branchement de la désintégration Lambdab -> pKμ⁺μ⁻ est effectuée avec une précision statistique de 5,3%.En outre, cette thèse présente la première observation de la désintégration Lambdab -> pKe⁺e ⁻ , ainsi que la mesure de son rapport de branchement.Enfin, la désintégration Xib0 -> pKJ/ψ est observée et étudiée pour la première fois
Flavor-changing neutral-current b ->sl⁺l⁻ transitions are forbidden at tree level in the Standard Model (SM), and can only occur at loop level. Therefore, they are sensitive to possible New Physics (NP) effects beyond the SM. In the SM, the transitions b ->se⁺e⁻ and b -> sμ⁺μ⁻ have the same probability to happen, this property is called lepton universality (LU). Probing LU in b-hadron decays has been recently a promising area for NP searches. Tensions with respect to the SM predictions at the level of about 2.5 standard deviations have been observed in rare B -> K(*)l⁺l ⁻ decays. To date, tests of LU have been performed only in decays of b-mesons.This thesis presents a first test of the LU in rare b-baryon decays Lambdab -> pK l⁺l⁻ using the data collected by the LHCb experiment at CERN, during 2011, 2012 and 2016 data-taking periods. The expected statistical sensitivity is about 15%, while the central value remains blind at the moment. The first measurement of the branching fraction of the decay Lambdab -> pKμ⁺μ⁻ is performed with the statistical precision of 5.3%.In addition, this thesis presents the first observation of the Lambdab -> pKe⁺e ⁻ decay, and the measurement of its branching fraction.Finally, a suppressed decay Xib0 -> pKJ/ψ is observed and studied for the first time

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Grahl, Mara [Verfasser], Dirk-Hermann [Akademischer Betreuer] Rischke et Bengt [Akademischer Betreuer] Friman. « Low-energy effective models for two-flavor quantum chromodynamics and the universality hypothesis / Mara Grahl. Gutachter : Dirk-Hermann Rischke ; Bengt Friman. Betreuer : Dirk-Hermann Rischke ». Frankfurt am Main : Univ.-Bibliothek Frankfurt am Main, 2014. http://d-nb.info/105184844X/34.

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Chapitres de livres sur le sujet "Flavour Universality"

Pescatore, Luca. « Testing Lepton Flavour Universality with $${\mathcal R}_{{K} ^{*0}} $$ ». Dans Searching for New Physics in b → sℓ+ℓ− Transitions at the LHCb Experiment, 105–57. Cham : Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-66423-1_5.

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Choudhury, Seema. « Recent Results on Lepton Flavor Universality Test at Belle ». Dans Springer Proceedings in Physics, 231–35. Singapore : Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-2354-8_42.

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Das, Nilakshi, et Rupak Dutta. « Exploring Lepton Flavor Universality Violation in $$B_s\rightarrow {D_s^*}\,l \,\nu $$ Decay ». Dans Springer Proceedings in Physics, 439–43. Singapore : Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-6292-1_56.

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Dutta, Rupak, et N. Rajeev. « Signature of Lepton Flavor Universality Violation in $$B_s \rightarrow D_s \tau \nu $$ Semileptonic Decays ». Dans Springer Proceedings in Physics, 489–93. Cham : Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-29622-3_68.

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Brinton, Daniel A., et Charles P. Wilkinson. « Selection of Surgery for “Routine” Retinal Detachment ». Dans Retinal Detachment. Oxford University Press, 2009. http://dx.doi.org/10.1093/oso/9780195330823.003.0015.

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Most rhegmatogenous retinal detachments are blinding disorders unless they are successfully repaired. They were regarded as incurable until the seminal work of Jules Gonin in the 1920s, when an anatomical success rate approaching 50% was first described (see Chapter 1). Anatomical results for routine retinal detachments slowly improved through several decades, reaching the current 85%–90% single-operation success figure for scleral buckling by the 1980s. Unfortunately, a similar improvement in visual results has not occurred because of the profound influence of preoperative macular detachment. Scleral buckling, once the sole standard of care for uncomplicated cases, has become much less popular worldwide with the development of alternative options starting in the mid 1980s. The most enduring of these are pneumatic retinopexy (PR) (described in Chapter 8) and vitrectomy (described in Chapter 9). Vitrectomy was originally reserved for complicated detachments but became popular for more routine cases as experience and equipment improved. Today, particularly in the United States, scleral buckling, PR, and vitrectomy are standards of care that are widely employed in the management of “routine” or “uncomplicated” retinal detachment, but how frequently each is used varies among different demographic groups. For instance, the popularity of PR varies by geographical location and scleral buckling appears less popular in the hands of relatively young vitreoretinal specialists. It can be useful to discuss objective clinical criteria that may favor one technique over another. Demarcation, scleral buckling, PR, vitrectomy, and vitrectomy plus scleral buckling have relative indications and contraindications (Table 10–1), as well as limitations and complications. In this brief chapter, clinical factors that may influence the choice of one technique over another, for the types of cases in which scleral buckling, PR, and/or vitrectomy are neither mandatory nor contraindicated, are discussed. However, it appears clear that we will never universally agree on the “best” operation for a given case, just as a single ice cream flavor will never be favored by all. There are several relatively common types of uncomplicated retinal detachments (Table 10–2), as well as numerous variables associated with all of them (Table 10–3). Management of retinal detachments with each specific technique is described in Chapters 7, 8, and 9.

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Actes de conférences sur le sujet "Flavour Universality"

Dordei, Francesca. « Lepton Flavour Universality at LHCb ». Dans The 20th International Workshop on Neutrinos. Trieste, Italy : Sissa Medialab, 2019. http://dx.doi.org/10.22323/1.341.0133.

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Stangl, Peter. « Lepton flavour universality violation from composite muons ». Dans The European Physical Society Conference on High Energy Physics. Trieste, Italy : Sissa Medialab, 2016. http://dx.doi.org/10.22323/1.234.0555.

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Paradisi, Paride. « Theory of lepton universality, flavour and number violation ». Dans 9th International Workshop on the CKM Unitarity Triangle. Trieste, Italy : Sissa Medialab, 2017. http://dx.doi.org/10.22323/1.291.0067.

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Martinez, Miriam Lucio. « Lepton flavour violation and universality tests at LHCb ». Dans The Eighth Annual Conference on Large Hadron Collider Physics. Trieste, Italy : Sissa Medialab, 2020. http://dx.doi.org/10.22323/1.382.0115.

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Podolsky, Sergey. « Lepton flavour universality and lepton flavour conservation tests in kaon decays at CERN. » Dans The XXI International Workshop High Energy Physics and Quantum Field Theory. Trieste, Italy : Sissa Medialab, 2014. http://dx.doi.org/10.22323/1.183.0034.

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Neshatpour, Siavash, Tobias Hurth, Farvah Mahmoudi et Diego Martinez Santos. « Implications of LHCb Data for Lepton Flavour Universality Violation ». Dans The European Physical Society Conference on High Energy Physics. Trieste, Italy : Sissa Medialab, 2022. http://dx.doi.org/10.22323/1.398.0564.

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Plana, Beatriz García. « Tests of Lepton Flavour Universality and Related Anomalies at LHCb ». Dans Workshop on Heavy Particles and Flavours. WORLD SCIENTIFIC, 2019. http://dx.doi.org/10.1142/9789811200380_0002.

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Marin Benito, Carla. « Lepton Flavour Universality tests in electroweak penguin decays at LHCb ». Dans 40th International Conference on High Energy physics. Trieste, Italy : Sissa Medialab, 2021. http://dx.doi.org/10.22323/1.390.0400.

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Schmitt, Sebastian. « Lepton flavour universality tests in electroweak penguin decays at LHCb ». Dans 41st International Conference on High Energy physics. Trieste, Italy : Sissa Medialab, 2022. http://dx.doi.org/10.22323/1.414.0737.

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