Littérature scientifique sur le sujet « Fermion mixing »

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Articles de revues sur le sujet "Fermion mixing"

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KIKUKAWA, YOSHIO. « CHIRAL SYMMETRY AND OPERATOR MIXING IN LATTICE SU(N) THIRRING MODEL WITH SHIFT SYMMETRY ». Modern Physics Letters A 07, no 10 (28 mars 1992) : 871–80. http://dx.doi.org/10.1142/s0217732392003517.

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We formulate lattice SU (N) Thirring model in which two Wilson fermions describe the respective left- and right-handed components of the Dirac fermion in the continuum model. Only chirally projected half components of the Wilson fermions have four-fermion interaction. As to their non-interacting components, there exist shift symmetries discussed by Golterman and Petcher. Axial U (1) Ward-Takahashi identity is examined by weak coupling expansion. It is shown in all orders of the weak coupling expansion that the chiral limit is achieved by simply setting fermion bare mass equal to zero, and that a lattice operator has no mixing due to the Wilson masses with the operators of wrong chiral representation and of lower dimensionality.
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Chiappinelli, Anna. « Exotic fermion mixing revisited ». Physics Letters B 269, no 1-2 (octobre 1991) : 123–28. http://dx.doi.org/10.1016/0370-2693(91)91462-5.

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Das, Ashok K., Jorge Gamboa, Fernando Méndez et Natalia Tapia. « Testing dark matter with the anomalous magnetic moment in a dark matter quantum electrodynamics model ». Modern Physics Letters A 32, no 33 (19 octobre 2017) : 1750175. http://dx.doi.org/10.1142/s0217732317501759.

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We consider a model of dark quantum electrodynamics (QEDs) which is coupled to a visible photon through a kinetic mixing term. We compute the [Formula: see text] for the dark fermion, where [Formula: see text] is its gyromagnetic factor. We show that the [Formula: see text] of the dark fermion is related to the [Formula: see text] of (visible) QEDs through a constant which depends on the kinetic mixing factor. We determine [Formula: see text] as a function of the mass ratio [Formula: see text], where [Formula: see text] and [Formula: see text] denote the masses of the dark photon and the dark fermion, respectively, and we show how [Formula: see text] becomes very different for light and heavy fermions around [Formula: see text] eV.
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Kaloshin, A. E., et V. P. Lomov. « Mixing of fermions and spectral representation of propagator ». International Journal of Modern Physics A 31, no 08 (14 mars 2016) : 1650031. http://dx.doi.org/10.1142/s0217751x16500317.

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We develop the spectral representation of propagator for [Formula: see text] mixing fermion fields in the case of [Formula: see text]-parity violation. The approach based on the eigenvalue problem for inverse matrix propagator makes possible to build the system of orthogonal projectors and to represent the matrix propagator as a sum of poles with positive and negative energies. The procedure of multiplicative renormalization in terms of spectral representation is investigated and the renormalization matrices are obtained in a closed form without the use of perturbation theory. Since in theory with [Formula: see text]-parity violation the standard spin projectors do not commute with the dressed propagator, they should be modified. The developed approach allows us to build the modified (dressed) spin projectors for a single fermion and for a system of fermions.
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Głazek, Stanisław D. « Fermion Mass Mixing in Vacuum ». Few-Body Systems 55, no 5-7 (30 novembre 2013) : 535–44. http://dx.doi.org/10.1007/s00601-013-0743-9.

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Hannabuss, K. C., et D. C. Latimer. « Fermion mixing in quasifree states ». Journal of Physics A : Mathematical and General 36, no 4 (15 janvier 2003) : L69—L79. http://dx.doi.org/10.1088/0305-4470/36/4/101.

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LEMKE, E. H. « NATURAL HIERARCHICAL FLAVOR MIXING ». Modern Physics Letters A 07, no 13 (30 avril 1992) : 1175–84. http://dx.doi.org/10.1142/s0217732392003633.

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We consider standard fermion doublets and Dirac fermions within the framework of a radiative mechanism of mass generation. The mass matrix represents a solution of a multi-gap equation. Taking such a solution, we compute the mass matrix of the upper (lower) members of the doublets with respect to the basis where the lower (upper) members have a mass matrix that is flavor-diagonal. If this form lies in the vicinity of its diagonalized mass matrix, the mixing will be called "natural." Naturalness relations between the products of mixing angles and ratios of flavor masses result. They are of substantial predictive power in both the case of the quarks and the leptons.
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Lu, Wei. « A Clifford algebra approach to chiral symmetry breaking and fermion mass hierarchies ». International Journal of Modern Physics A 32, no 26 (20 septembre 2017) : 1750159. http://dx.doi.org/10.1142/s0217751x17501597.

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We propose a Clifford algebra approach to chiral symmetry breaking and fermion mass hierarchies in the context of composite Higgs bosons. Standard model fermions are represented by algebraic spinors of six-dimensional binary Clifford algebra, while ternary Clifford algebra-related flavor projection operators control allowable flavor-mixing interactions. There are three composite electroweak Higgs bosons resulted from top quark, tau neutrino, and tau lepton condensations. Each of the three condensations gives rise to masses of four different fermions. The fermion mass hierarchies within these three groups are determined by four-fermion condensations, which break two global chiral symmetries. The four-fermion condensations induce axion-like pseudo-Nambu–Goldstone bosons and can be dark matter candidates. In addition to the 125 GeV Higgs boson observed at the Large Hadron Collider, we anticipate detection of tau neutrino composite Higgs boson via the charm quark decay channel.
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CHAMOUN, N., et S. KHALIL. « FERMION MASSES AND MIXING IN FOUR AND MORE DIMENSIONS ». International Journal of Modern Physics A 21, no 31 (20 décembre 2006) : 6267–301. http://dx.doi.org/10.1142/s0217751x06033131.

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We give an overview of recent progress in the study of fermion mass and flavor mixing phenomena. Mass matrix ansatze are considered within the Standard Model (SM) and SUSY GUT's where some predictive frameworks based on SU(5) and SO(10) are reviewed. We describe a variety of schemes to construct quark mass matrices in extra dimensions focusing on four major classes: models with the SM residing on 3-brane, models with universal extra dimensions, models with split fermions and models with warped extra dimensions. We outline how realistic patterns of quark mass matrices could be derived from orbifold models in heterotic superstring theory. Finally, we address the fermion mass problem in intersecting D-branes scenarios, and present models with D6-branes able to give a good quantitatively description of quark masses and mixing. The role of flavor/CP violation problem as a probe of new physics is emphasized.
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Vien, Vo Van, et Hoang Ngoc Long. « Neutrino mixing with nonzero θ13 and CP violation in the 3-3-1 model based on A4 flavor symmetry ». International Journal of Modern Physics A 30, no 21 (22 juillet 2015) : 1550117. http://dx.doi.org/10.1142/s0217751x15501171.

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We propose a 3-3-1 model with neutral fermions based on [Formula: see text] flavor symmetry responsible for fermion masses and mixings with nonzero [Formula: see text]. To get realistic neutrino mixing, we just add a new [Formula: see text] triplet being in [Formula: see text] under [Formula: see text]. The neutrinos get small masses from two [Formula: see text] antisextets and one [Formula: see text] triplet. The model can fit the present data on neutrino masses and mixing as well as the effective mass governing neutrinoless double beta decay. Our results show that the neutrino masses are naturally small and a little deviation from the tri-bimaximal neutrino mixing form can be realized. The Dirac CP violation phase [Formula: see text] is predicted to either [Formula: see text] or [Formula: see text] with [Formula: see text].
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Thèses sur le sujet "Fermion mixing"

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Therrien, Eric. « Fermion masses and mixing in a simple composite model ». Thesis, McGill University, 1987. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=63874.

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Hudspith, Renwick. « Gauge fixed gluonic observables and neutral kaon mixing on the lattice ». Thesis, University of Edinburgh, 2013. http://hdl.handle.net/1842/8269.

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This thesis presents gauge fixed gluonic observable and neutral Kaon mixing matrix element measurements using nf=2+1 Domain Wall Fermion (DWF) configurations. These were generated with the Iwasaki gauge action by the RBC and UKQCD collaborations. Results from the first measurement of the QCD strong coupling with these ensembles using the triple gluon vertex are shown. We find that while a very accurate measurement of the coupling is possible using this technique, the systematic error from the perturbative matching at current lattice scales is large. We also discuss the utilisation of this method as a probe for possible Technicolor theories. The calculation of the QCD strong coupling constant from the triple gluon vertex required an implementation of a fast code to fix lattice gauge configurations. I provide details on my implementation of a parallel and optimised Fourier-accelerated algorithm for both Landau and Coulomb gauge fixing. I include the first calculation of the highly accurate W0-scale using these ensembles, allowing for percent-level scale setting. I show results from a wide variety of smearing methods and present the first gluonic measurement of different smearing radii. This thesis also details the first nf=2+1 measurement of the BSM neutral Kaon mixing renormalised matrix elements from lattice simulations with almost exact chiral symmetry in the valence sector and the sea.
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BELFATTO, BENEDETTA. « Flavour problems and new physics at TeV scale ». Doctoral thesis, Gran Sasso Science Institute, 2020. http://hdl.handle.net/20.500.12571/10042.

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There is no explanation in the Standard Model for the replication of fermion families, neither for the mass hierarchy between them nor for the structure of the Yukawa coupling matrices, which remain arbitrary. The key towards under- standing the fermion masses and mixing pattern can be in symmetry principles. Masses of fermions can actually have a dynamical origin, following the spon- taneous symmetry breaking of gauge “horizontal" symmetries unifying families, differently acting on left and right species. U(3) or SU(3) “horizontal" family symmetries seem an intuitive hypothesis to be considered. Fermion masses should be induced by higher order operators containing flavon scalars emerging from renormalizable interactions via ‘universal seesaw’ mechanism after integrat- ing out some heavy fields, scalars or verctor-like fermions. Then in this case the fermion mass hierarchy and mixing among families can be related to the pat- tern of spontaneous breaking of the gauge SU(3) symmetry. The corresponding gauge bosons have flavor-nondiagonal couplings to fermions which in principle can induce flavour changing phenomena. In this case strong lower limits on the flavor symmetry breaking scales are expected. However, for special choices of horizontal symmetries there is a natural suppression of flavour changing effects due to a custodial symmetry. So gauge bosons can have mass in the TeV range, without contradicting the existing experimental limits. However an unexpected anomaly shows up in quark mixing. After the recent high precision determinations of Vus and Vud, the first row of the CKM matrix is about 4σ deviated from unitarity. The existence of the gauge symmetry SU(3)l acting between lepton families can recover unitarity if the symmetry is broken at a scale of about 6 TeV. In fact the gauge bosons of this symmetry contribute to muon decay in interference with the Standard Model, so that the Fermi constant is slightly smaller than the muon decay constant and unitarity is restored. Alternatively, extra vector-like quarks can be thought as a solution to the CKM unitarity problem. The extra species should exhibit a large mixing with the first family in order to recover unitarity, then their mass should be no more than 6 TeV or so. The implications of the existence of so large mixing must be examined, in order to understand if it can actually exist without contradiction with experimental results on flavour changing neutral current processes and Standard Model observables. In principle an extra weak isodoublet can solve all the discrepancies between independent determinations of the CKM elements in the first row. However not all the discrepancies can be entirely recovered with- out contradicting experimental constraints. Then the existence of two or more vector-like doublets or a vector-like isodoublet with a down-type or up-type isos- inglet can be considered. In these scenarios unitarity can be resettled and flavour changing can be avoided by setting to zero some couplings of extra species with Standard Model families. If the anomalies in the determination of CKM mixing angles are confirmed by future experiments with greater precision, there might be strong indication towards the existence of physics beyond the Standard Model at the TeV scale, such as flavour changing gauge bosons and vector-like fermions with masses of few TeV. This new physics can be testable at next runs of high luminosity LHC or, more effectively, in future accelerators.
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Deppisch, Thomas Ludwig [Verfasser], et U. [Akademischer Betreuer] Nierste. « A Tale of Scales - Fermion Masses and Mixing in Minimal Supersymmetric SO($_10}$) and Resummation of Gluino Contributions to the MSSM Higgs Potential / Thomas Ludwig Deppisch ; Betreuer : U. Nierste ». Karlsruhe : KIT-Bibliothek, 2019. http://d-nb.info/1187343366/34.

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de, Medeiros Varzielas Ivo. « Family symmetries and the origin of fermion masses and mixings ». Thesis, University of Oxford, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.497464.

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Dück, Alexander [Verfasser], et Werner [Akademischer Betreuer] Rodejohann. « Phenomenology of Neutrinos and Possible SO(10) Origins of Fermion Masses and Mixings / Alexander Dück ; Betreuer : Werner Rodejohann ». Heidelberg : Universitätsbibliothek Heidelberg, 2012. http://d-nb.info/1177148234/34.

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Menzel, Andreas. « Constraints on the Fourth-Generation Quark Mixing Matrix from Precision Flavour Observables ». Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2017. http://dx.doi.org/10.18452/17711.

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Das Standardmodell einer zusätzlichen sequentiellen Fermiongeneration (SM4) war 2012 auf Basis eines Fits an elektroschwache Präzisionsobservable und die Higgs-Signalstärken mit einer Signifikanz von 5.3 sigma ausgeschlossen worden. Komplementär dazu wurden in der vorliegenden Arbeit Fits des SM4 an eine Kombination eines typischen Satzes von Flavour-Observablen mit den Ergebnissen des zuvor durchgeführten Elektroschwachen Präzisionsfits durchgeführt. Im SM3-Kontext extrahierte Größen wurden gemäß ihrer Bedeutung im SM4 reinterpretiert und die angepassten theoretischen Ausdrücke angegeben. Die resultierenden Einschränkungen der CKM-Matrix des SM4, ihrer potentiell CP-verletzenden Phasen sowie der Masse des up-type-Quarks der 4. Generation t'' werden angegeben. Zum Vergleich des SM4 mit dem SM3 werden die erreichten chi^2-Werte genutzt. chi^2=15.53 im SM4 und 9.56 im SM3 passen fast vollkommen zu einer gleich guten Beschreibung der Experimente durch beide Modelle, wobei das SM3 aber sechs Freiheitsgrade mehr besitzt. Außerdem wurden die Vorhersagen des SM3 und des SM4 für die Dimyon-Ladungsasymmetrie ASL mit experimentellen Werten verglichen. Die Vorhersage des SM3 ist ca. 2 sigma vom experimentellen Wert entfernt, die des SM4 ca. 3 sigma.\par Die Ergebnisse deuten nicht darauf hin, dass die Signifikanz des 2012 erreichten Ausschlusses des SM4 durch die Hinzunahme von Flavour-Observablen zu den damals verwendeten elektroschwachen Präzisionsobservablen und Higgs-Querschnitten bedeutend verringert würde.\par Es konnte jedoch keine genaue quantitative Aussage über die Auswirkungen der Flavourobservablen auf diese Signifikanz getroffen werden, weil das Programm CKMfitter likelihood-ratio-Berechnung nur durchführen kann, wenn sich eines der untersuchten Modelle durch Fixierung von Parametern aus dem anderen ergibt (nested models), was hier nicht der Fall ist.
The Standard Model extended by an additional sequential generation of Dirac fermions (SM4) was excluded with a significance of 5.3 sigma in 2012. This was achieved in a combined fit of the SM4 to Electroweak Precision Observables and signal strengths of the Higgs boson. This thesis complements this excludion by a fit of the SM4 to a typical set of Flavour physics observables and the results of the previously performed Electroweak Precision fit. Quantities extracted in an SM3 framework are reinterpreted in SM4 terms and the adapted theoretical expressions are given. The resultant constraints on the SM4''s CKM matrix, its potentially CP-violating phases and the mass of the new up-type quark t'' are given. To compare the relative performance of the SM4 and the SM3, this work uses the chi^2 values achieved in the fit. The values of 15.53 for the SM4 and 9.56 for the SM4 are almost perfectly consistent with both models describing the experimental data equally well with the SM3 having six degrees of freedom more. The dimuon charge asymmetry ASL was not used as a fit input because the interpretation of its measurement was subject to debate at the time when the fits were produced, but its prediction in the fit was used as an additional test of the SM4. The SM3''s prediction differs from the experimental values by about 2 sigma, and the SM4''s prediction by about 3 sigma. \par In summary, these results do not suggest that any significant reduction of the 5.3 sigma exclusion could be achieved by combining the Electroweak Precision Observables and Higgs inputs with Flavour physics data. However, the exact effect of the Flavour physics input on the significance of the SM4''s exclusion cannot be given at this point because the CKMfitter software is currently not able to perform a statistically stringent likelihood comparison of non-nested models.
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Mollet, Simon. « Exploration of 6-dimensional models with non trivial topology and their predictions for fermions masses and mixings, neutrino physics, flavour changing interactions and CP violation ». Doctoral thesis, Universite Libre de Bruxelles, 2016. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/230863.

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In this thesis, we study several scenarios which go beyond the Standard Model of particle physics with the aim of gaining a better understanding for the multiplication of fermion families, their masses and mixings pattern and its relation to CP violation. The common feature of the models we envisaged (and the guiding principle of the thesis) is the introduction of extra space dimensions. In a first attempt to explain the fermion mass structure, we elaborate on a model with two extra-dimensions and a Nielsen- Olesen vortex background established on it. In this framework, three families in 4D can be seen as different modes of a single generation in 6D, while their extra-dimensional wavefunctions turn out highly constrained by the dynamics, which allows to determined the mass matrices with few parameters. Moreover, with a few additional hypotheses only, it is possible to simultaneously account for the striking differences between neutrinos and charged fermions. After a summary of the model, we illustrate this with the explicit formulation of a benchmark model which reproduces convincingly all the mass and mixing parameters of the Standard Model, taking advantage of new, more precise numerical solutions of the field equations, and including the recent measurements of the Standard Model scalar boson mass and of the neutrino heta_13 mixing angle (the latter has however been correctly predicted by the model before its first measurement). We then turn to the predictions which mainly concern the neutrino and gauge sectors. In the former, we remind the Majorana nature, and the natural tendency for inverted hierarchy pattern with an almost maximally suppressed neutrinoless double beta decay. On the other hand, we predict new (neutral) gauge bosons whose couplings to fermions are not flavour-diagonal but are however constrained (in their strength and their flavour structure) by the 6D anatomy of the theory. We compare their detectability in precision low energy processes and at colliders (especially at the LHC), and show that in the simplest geometries at least, the bounds from the former exclude interesting phenomenology for the latter. Nevertheless, we turn to more phenomenological effective Lagrangians with the same overall structure and in which we are able to lower the mass scale of the new bosons to a reachable energy, and thus analyse the possible signatures for LHC.In the last part of this work, we turn to the issue of CP violation and show how in certain 6D models with non simply connected topologies, it is possible to generate a non negligible CP violation at the 4D level in a pure gauge approach. We carefully study how the 4D CP symmetry is related to particular transformations of the original 6D theory and subsequently show how an incompatibility of such transformations with the compactification scheme can lead to an effective CP breaking. As a proof of concept, we build a toy model with two extra-dimensions compactified on a flat torus and end in 4D with a light neutral fermion with a non zero electric dipole moment.Dans cette thèse, nous étudions plusieurs scénarios au-delà du Modèle Standard de la physique des particules à la recherche d'une meilleure compréhension de la multiplication des familles de fermions, de leurs masses et de leurs mélanges, ainsi que la relation à laviolation de CP.La caractéristique commune à tous les modèles envisagés (et le concept sous-jacent à toute la thèse) est l'introduction de nouvelles dimensions spatiales. Dans une première tentative pour expliquer le spectre des fermions, nous développons un modèle où une structure de vortex à la Nielsen-Olesen est établie sur deux dimensions supplémentaires. Dans ce cadre, les trois familles à 4D peuvent être vues comme différents modes d'une unique génération à 6D, tandis que leur fonctions d'onde extra-dimensionnelles s'avèrent fortement contraintes par la dynamique ;ceci permet d'établir les matrices de masses en terme d'un petit nombre de paramètres. De plus, grâce à quelques hypothèses additionnelles seulement, il est possible de justifier simultanément les différences marquées entre neutrinos et fermions chargés. Nous synthétisons le modèle et l'illustrons en en formulant une réalisation particulière qui parvient à reproduire de manière convaincante tous les paramètres de masse et de mélange du Modèle Standard. Pour l'occasion, nous exploitons de nouvelles solutions aux équations des champs, numériquement plus précises, et prenons en compte les mesures récentes de la masse du boson scalaire et de l'angle de mélange heta_13 pour les neutrinos (le modèle avait cependant prédit ce dernier avant qu'il ne soit mesuré pour la première fois). Nous nous tournons ensuite vers les prédictions du modèle et qui concernent principalement le secteur des neutrinos et celui des bosons de jauge. Pour le premier, nous rappelons la nature "Majorana" des neutrinos, ainsi que la tendance naturelle à une hiérarchie inverse avec une suppression quasi maximale de la double désintégration bêta sans neutrino. D'autre part, nous prédisons de nouveaux bosons de jauge (neutres) dont les couplages aux fermions ne sont pas diagonaux dans l'espace des saveurs mais sont contraints (autant en terme de valeurs qu'en termes de structure) par l'anatomie de la théorie à 6D. Nous comparons leurs détections potentielles dans les processus de précision à basse énergie et auprès des collisionneurs (en particulier au LHC). Nous montrons que, dans les géométries les plus simples du moins, les limites imposées par les premiers excluent toute phénoménologie intéressante du côté des seconds. Toutefois, en nous tournantvers des Lagrangiens effectifs qui conservent la même structure d'ensemble mais ouvrent à une étude plus phénoménologique, nous sommes capables de réduire l'échelle de masse de ces nouveaux bosons jusqu'à une énergie accessible, et donc d'en analyser de potentielles signatures au LHC.Dans la dernière partie de ce travail, nous nous intéressons à la question de la violation de CP et montrons comment dans certains modèles à 6D avec une topologie non-simplement connexe, il est possible de générer une violation de CP non négligeable à 4D dans une approche de "pure jauge". Nous étudions attentivement comment la symétrie CP à 4D est reliée à des transformations particulières de la théorie originale à 6D, suite à quoi nous montrons comment l'incompatibilité de ces transformations avec la façon dont sont "compactifiées" les dimensions supplémentaires peut conduire à une brisure effective de CP. Pour illustrer la faisabilité de notre approche, nous élaborons un "modèle jouet" où deux dimensions supplémentaires sont compactifiées sur un tore plat, et obtenons à 4D un fermion neutre léger et qui possède un moment électrique dipolaire non nul.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished
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Pientka, Grit. « Hadronic corrections to electroweak observables from twisted mass lattice QCD ». Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2015. http://dx.doi.org/10.18452/17312.

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Für verschiedene Richtgrößen, die untersucht werden, um Hinweise auf Neue Physik jenseits des Standardmodells der Teilchenphysik zu finden, stellt die Gitter-QCD stellt derzeit den einzigen Ab-initio-Zugang für die Berechnung von nichtperturbativen hadronischen Beiträgen dar. Zu diesen Observablen gehören die anomalen magnetischen Momenten der Leptonen und das Laufen der elektroschwachen Kopplungskonstanten. Wir bestimmen den führenden QCD-Beitrag zum anomalen magnetischen Moment des Myons mit Hilfe einer Gitter-QCD-Rechnung auf Ensemblen, die Nf=2+1+1 dynamische Twisted-Mass-Fermionen berücksichtigen. Durch die Betrachtung aktiver up, down, strange and charm Quarks können erstmalig Gitter-QCD-Daten für die Myonanomalie direkt mit phänomenologischen Resultaten verglichen werden, da letztere bei der derzeitigen Genauigkeit sensitiv auf die ersten beiden Quarkgenerationen sind. Unlängst wurde darauf hingewiesen, dass es auch möglich sein könnte Beiträge Neuer Physik durch verbesserte Messungen der anomalen magnetischen Momente des Elektrons und des Tauons nachzuweisen. Aus diesem Grund berechnen wir auch deren führende QCD-Beiträge, was gleichzeitig eine Überprüfung des Wertes für das Myon liefert. Zusätzlich nutzen wir die gewonnenen Daten, um den führenden hadronischen Beitrag zum Laufen der Feinstrukturkonstante zu berechnen. Darüber hinaus zeigen wir, dass sogar für den schwachen Mischungswinkel der führende QCD-Beitrag mit Hilfe dieser Daten berechnet werden kann. Dadurch identifizieren wir eine neue grundlegende Observable für die Suche nach Neuer Physik, deren hadronische Beiträge mit Hilfe der Gitter-QCD beschafft werden können. Mit den Resultaten dieser Arbeit ist es uns gelungen ungeeignete Herangehensweisen der phänomenologisch notwendigen Flavourseparation auszuschließen und somit direkt die derzeit präziseren phänomenologischen Bestimmungen dieser bedeutsamen physikalischen Größe zu unterstützen.
For several benchmark quantities investigated to detect signs for new physics beyond the standard model of elementary particle physics, lattice QCD currently constitutes the only ab initio approach available at small momentum transfers for the computation of non-perturbative hadronic contributions. Among those observables are the lepton anomalous magnetic moments and the running of the electroweak coupling constants. We compute the leading QCD contribution to the muon anomalous magnetic moment by performing lattice QCD calculations on ensembles incorporating Nf=2+1+1 dynamical twisted mass fermions. Considering active up, down, strange, and charm quarks, admits for the first time a direct comparison of the lattice data for the muon anomaly with phenomenological results because both the latter as well as the experimentally obtained values are sensitive to the complete first two generations of quarks at the current level of precision. Recently, it has been noted that improved measurements of the electron and tau anomalous magnetic moments might also provide ways of detecting new physics contributions. Therefore, we also compute their leading QCD contributions, which simultaneously serve as cross-checks of the value obtained for the muon. Additionally, we utilise the obtained data to compute the leading hadronic contribution to the running of the fine structure constant, which enters all perturbative QED calculations. Furthermore, we show that even for the weak mixing angle the leading QCD contribution can be computed from this data. In this way, we identify a new prime observable in the search for new physics whose hadronic contributions can be obtained from lattice QCD. With the results obtained in this thesis, we are able to exclude unsuitable phenomenologically necessary flavour separations and thus directly assist the presently more precise phenomenological determinations of this eminent quantity.
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Le, Bloas Julien. « Mélange d’isospin et désintégration Beta ». Thesis, Bordeaux 1, 2011. http://www.theses.fr/2011BOR14309/document.

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Dans ce travail, nous nous sommes intéressés à la brisure de la symétrie d'isospin dans les noyaux N≈Z et à son effet sur l'élément de matrice de transitions β de Fermi super-permises 0+ ➝ 0+ dans le cas de la décroissance β+ du Mn50.Dans le cadre de l'approche microscopique Highly Truncated Diagonalization Approach (HTDA), dédiée à la description des corrélations au-delà du champ moyen et conservant explicitement de nombre de particules, nous avons étudié (en particulier) le rôle joué par les corrélations d'appariement dans les mécanismes de brisure de la symétrie d'isospin dans l'état fondamental de noyaux N≈Z. Une étude de sensibilité du degré de cette brisure, en fonction de l'intensité de l'interaction résiduelle décrivant l'appariement dans HTDA, a été menée et une interprétation des mécanismes recherchés a été proposée à l'aide d'une approximation développée dans ce travail. Cette étude a mis évidence toute la complexité d'un bon traitement de la symétrie d'isospin, tant au niveau de la description de la source de brisure qu'au niveau de la limitation des biais du modèle. Nous avons également montré la nécessité d'une description très fine des fonctions d'onde corrélées dans un tel problème. Plus précisément, nous avons obtenu une valeur de la correction δc de mélange d'isospin à l'élément de matrice de transition de Fermi de (0.2±0.1)%. Cette valeur a été confrontée à celles obtenues dans d'autres approches. Compte tenu des effets négligés dans notre travail, notre valeur de δc est supposée représenter une borne minimum
In this work, we are interested in the breaking of the isospin symmetry in the N≈Z nuclei and in its effect on the matrix element of super-allowed 0+ ➝ 0+ Fermi β transitions in the case of the β+ decay of the Mn50. Within the framework of the Highly Truncated Diagonalization microscopic Approach, dedicated to the descritption of correlations beyond the mean field and conserving explicitely the particle number, we have studied (in particular) the role played by pairing correlations in the breaking mechanisms of this symmetry in the ground state of N≈Z nuclei. A sensitivity study of the isospin mixing, as a function of the strength of the residual interaction decribing the pairing correlations in HTDA, has been carried out and an interpretation of the mechanims at work has been proposed in terms of an approximation developped in this work. This study has pointed out the complexity of a good treatment of the isospin symmetry, in the description of the breaking sources as well as in the reduction of model biases. We have also paid attention to the necessity of a very fine description of the correlated wave functions in such a problem. More precisely, we have obtained a value for the isospin mixing correction δc to the Fermi transition matrix element of (0.2±0.1)%. This value has been compared to those obtained in other approaches. Taking account of the neglected effects in our work, our value of δc is expected to be a lower bound
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Livres sur le sujet "Fermion mixing"

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Esteban, Roulet, Tommasini Daniele et United States. National Aeronautics and Space Administration., dir. Global analysis of fermion mixing with exotics. [Batavia, Ill.?] : Fermi National Accelerator Laboratory, 1991.

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Chapitres de livres sur le sujet "Fermion mixing"

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Khalil, Shaaban, et Stefano Moretti. « Fermion Masses and Mixing ». Dans Standard Model Phenomenology, 109–20. Boca Raton : CRC Press, 2022. http://dx.doi.org/10.1201/9780429443015-10.

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Raby, Stuart. « Fermion Masses and Mixing in SUSY GUTs : Predictive Theories ». Dans Supersymmetric Grand Unified Theories, 71–85. Cham : Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-55255-2_9.

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Kemly, E., et M. Croft. « A Simple but Rigorous Model for Valence Mixing : Energy Levels, Thermodynamic Properties, and Phase Diagrams ». Dans Theoretical and Experimental Aspects of Valence Fluctuations and Heavy Fermions, 573–76. Boston, MA : Springer US, 1987. http://dx.doi.org/10.1007/978-1-4613-0947-5_93.

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Ormand, W. E., et B. A. Brown. « Recent Calculations of Isospin-Mixing Corrections to the Fermi Matrix Element in Superallowed β-Decay and the Determination of the Weak Vector Coupling Constant ». Dans Weak and Electromagnetic Interactions in Nuclei, 545–47. Berlin, Heidelberg : Springer Berlin Heidelberg, 1986. http://dx.doi.org/10.1007/978-3-642-71689-8_104.

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Terranova, Francesco. « At the forefront of the Standard Model ». Dans A Modern Primer in Particle and Nuclear Physics, 368–419. Oxford University PressOxford, 2021. http://dx.doi.org/10.1093/oso/9780192845245.003.0013.

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Abstract The final chapter covers the least-known territories of the Standard Model (SM). It describes the Higgs mechanism using classical relativistic fields. We present the greatest achievement of the Large Hadron Collider (LHC): the discovery of the Higgs boson in 2012. The Higgs mechanism originates fermion masses, too. Lepton masses are covered first: the discovery of neutrino oscillations and the Pontecorvo–Maki–Nakagawa–Sakata (PMNS) mixing matrix. It then turns to the quark sector, stressing similarities and differences with leptons, especially in meson oscillations. The complex phase of the quark mixing matrix (CKM) and the evidence for CP violation are covered. Finally, the chapter looks at the failures of the Standard Model, introducing the idea of naturalness and the dark matter–dark energy problem. The book concludes with two masterpieces of experimental ingenuity that address these issues. The direct search of dark matter by XENON1T (2017) and the observation of gravitational waves by LIGO (2016).
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Mebratie Bogale, Gedefaw, et Dagne Atnafu Shiferaw. « Iron-Based Superconductors ». Dans High Entropy Materials - Microstructures and Properties [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.109045.

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Superconductivity is the phenomenon of vanishing an electrical resistivity of materials below a certain low temperature and superconductors are the materials that show this property. Critical temperature is the temperature below which superconducting state occurs. Based on temperature superconductors can be grouped into high-temperature superconductors and low-temperature superconductors. Based on the mechanism, they can be grouped into conventional and unconventional superconductors. Based on magnetism superconducting materials can also be separated into two groups: type-I and type-II superconductors. In this chapter, we will discuss superconductivity, the Meissner effect, type-I and type-II superconductors, convectional and unconvectional superconductors, heavy fermions, cuprates, iron-based superconductors, and high entropy alloy superconductors. High-entropy alloys (heas) are defined as alloys containing at least five elements with concentrations between 5 and 35 atom%. The atoms randomly distribute on simple crystallographic lattices, where the high entropy of mixing can stabilize disordered solid-solution phases with simple structures. The superconducting behavior of heas is distinct from copper oxide superconductors, iron-based superconductors, conventional alloy superconductors, and amorphous superconductors, suggesting that they can be considered as a new class of superconducting materials.
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Chou, K. C., et Y. L. Wu. « CP violation, fermion masses and mixings in a predictive SUSY SO(10) × Δ(48) × U(1) model with small tanβ ». Dans Selected Papers of K C Chou, 497–500. WORLD SCIENTIFIC, 2009. http://dx.doi.org/10.1142/9789814280389_0074.

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Chou, K. C., et Yue-Liang Wu. « A solution to the puzzles of CP violation, neutrino oscillation, fermion masses and mixings in an SUSY GUT model with small tanβ ». Dans Selected Papers of K C Chou, 514–17. WORLD SCIENTIFIC, 2009. http://dx.doi.org/10.1142/9789814280389_0076.

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Actes de conférences sur le sujet "Fermion mixing"

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Ross, G. G., Pyungwon Ko et Deog Ki Hong. « Fermion masses, flavour mixing and CP violation ». Dans SUPERSYMMETRY AND THE UNIFICATION OF FUNDAMENTAL INTERACTIONS. AIP, 2008. http://dx.doi.org/10.1063/1.3051900.

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Anderson, Gregory. « Exceptional models of fermion masses and mixing angles ». Dans Third Latin American Symposium on High Energy Physics. Trieste, Italy : Sissa Medialab, 2000. http://dx.doi.org/10.22323/1.005.0001.

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Gupta, Manmohan, Monika Randhawa et Gulsheen Ahuja. « Implications of texture specific mass matrices for fermion mixing phenomena ». Dans Proceedings of ICFP2001. WORLD SCIENTIFIC, 2002. http://dx.doi.org/10.1142/9789812777379_0049.

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Tsun, TSOU Sheung. « FERMION MASS AND MIXING PATTERNS FROM A ROTATING MASS MATRIX ». Dans In Celebration of the 80th Birthday of C N Yang. WORLD SCIENTIFIC, 2003. http://dx.doi.org/10.1142/9789812791207_0024.

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Rebelo, M. « Fermion Masses and Mixing resulting from Unimodular Complex Mass Matrices ». Dans Corfu Summer Institute on Elementary Particle Physics. Trieste, Italy : Sissa Medialab, 1999. http://dx.doi.org/10.22323/1.001.0061.

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Vale Silva, Luiz. « Probing squared four-fermion operators of SMEFT with meson-mixing ». Dans The European Physical Society Conference on High Energy Physics. Trieste, Italy : Sissa Medialab, 2022. http://dx.doi.org/10.22323/1.398.0519.

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Carcamo Hernandez, A., et Roberto Martinez. « Fermion mass and mixing pattern in a minimal T7 flavor 331 model ». Dans 18th International Conference From the Planck Scale to the Electroweak Scale. Trieste, Italy : Sissa Medialab, 2016. http://dx.doi.org/10.22323/1.258.0023.

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Hernandez - Galeana, Albino. « Fermion masses and mixing within a SU(3) family symmetry model with five sterile neutrinos ». Dans 1st Electronic Conference on Universe. Basel, Switzerland : MDPI, 2021. http://dx.doi.org/10.3390/ecu2021-09266.

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Mahanthappa, K. T., et Mu-Chun Chen. « Fermion Mixing and Soft Leptogenesis in a SUSY SO(10) X SU(2)_F Model ». Dans International Europhysics Conference on High Energy Physics. Trieste, Italy : Sissa Medialab, 2007. http://dx.doi.org/10.22323/1.021.0356.

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Lomov, Vladimir, Alexander Kaloshin et Elena Kobeleva. « Loop mixing of the opposite parity fermion fields and its manifestation in $\pi N$ scattering ». Dans XXII International Baldin Seminar on High Energy Physics Problems. Trieste, Italy : Sissa Medialab, 2015. http://dx.doi.org/10.22323/1.225.0123.

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Rapports d'organisations sur le sujet "Fermion mixing"

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Chou, Chih-Lung. Fermion Masses and Mixing in SUSY Grand Unified Gauge Models with Extended Gut Gauge Groups. Office of Scientific and Technical Information (OSTI), avril 2005. http://dx.doi.org/10.2172/839825.

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