118584962
Real time studies of quantum metastability
118526359
Abelian symmetries in the two-Higgs-doublet model with fermions
We classify all possible implementations of an abelian symmetry in the two-Higgs-doublet model with fermions. We identify those symmetries which are consistent with non-vanishing quark masses and a CKM matrix which is not block-diagonal. Our analysis takes us from a plethora of possibilities down to 246 relevant cases, requiring only 34 distinct matrix forms. We show that applying Z_n with n \geq 4 to the scalar sector leads to a continuous U(1) symmetry in the whole Lagrangian. Finally, we address the possibilities of spontaneous CP violation and of natural suppression of the flavour changing neutral currents. We explain why our work is relevant even for non-abelian symmetries.
117683940
Opportunities and Tests for Physics Beyond the Standard Model
1040688
Constraining new interactions with leptonic tau decays.
The recent measurements of the Michel parameters in {tau} decays enable, for the first time, a thorough analysis of the leptonic sector. In general, in models beyond the standard model, these parameters will be altered through changes in the {ital W} and {ital Z} couplings, and/or through interactions mediated by new gauge bosons. We perform a complete, model-independent analysis of the constraints imposed by the present data on such boson-mediated interactions, and point out the existence of useful relations among the couplings.
10678678
Decoupling or nondecoupling: Is that the R($b$) question?
The top quark is well known for the nondecoupling effects it implies in ρ and Rb. The recent experimental Rb data exhibits a disagreement with the SM prediction at more than the 3σ level. It is tempting to explore whether this might be due to nondecoupling New Physics effects, opposite to those of the top. We investigate this issue in the context of models with an extra family of right or left handed, singlet or doublet quarks. It is shown that, contrary to what
119065587
Exploring Fundamental Particles
GENESIS OF THE STANDARD MODEL The Foundation of Modern Physics: The Legacy of Newton Simple Quantitative Laws Fundamental Interactions Fields Cosmological Principles Was Newton Wrong? The Relation of New Theories to Old The Role of Probability Waves That Are Particles Particles That Are Waves Particles versus Waves What Is Light? Light Is a Wave The Birth of Special Relativity What Is Light? Light Is a Particle De Broglie and Schrodinger: The Electron as a Wave Particles That Spin Angular Momentum and Spin Helicity The Dirac Electron Polarization and the Photon Spin Understanding Quantum Electrodynamics: Feynman to the Rescue Quantum Field Theory and Feynman Diagrams Gregarious Particles and Lonesome Particles: Spin and Statistics The Birth of Particle Physics: Pauli's Neutrino, Fermi's Weak Interaction, and Yukawa's Pion Electron, Proton, and Neutron Beta Decay and Pauli's Neutrino Fermi's Weak Interaction Nuclear Forces and Yukawa's Pion The Muon: Who Ordered That? The Muon Neutrino: A New Kind of Nothing Strange Particles Learning to Live with Gell-Mann's Quarks Origin of the Quark Theory A Weekend in November: The Discovery of Charm Another Version of the Rutherford Scattering Experiment Quantum Chromodynamics Jets Beautiful Symmetries Found and Lost Discrete and Continuous Symmetries Mirror Symmetry: P for Parity Madame Wu's Amazing Discovery C for Charge Conjugation CP Symmetry T for Time Reversal Emergence of the Standard Model Weinberg: A Model of Leptons The Experimental Triumph of the Standard Model Flavor Physics Standard Model with Two Families Standard Model with Three Families The Cabibbo-Kobayashi-Maskawa Matrix Yukawa Couplings, Masses, and Mixing Our Current View of Nature's Building Blocks: (What We Have Learned So Far) The Four Interactions of Nature The Fundamental Building Blocks of Matter Interactions Are Mediated by Particles The Standard Model and Large Laboratories CP VIOLATION: THE ASYMMETRY BETWEEN MATTER AND ANTIMATTER CP Violation in Kaon Decays The Cabibbo-Kobayashi-Maskawa Matrix: CP Violation in the Standard Model CP Violation with B Mesons CP Violation at the B Factories CP Violation in the Bs System Checking the Standard Model: The Rho-Eta Plane CP Violation: Where Do We Go from Here? Further Constraints on the Rho-Eta Plane Quantities That Are Small in the Standard Model THE AMAZING STORY OF THE NEUTRINO The Mystery of the Missing Neutrinos: Neutrino Oscillations Neutrinos from the Sun Neutrino Astronomy: A New Way to Study the Universe Neutrinos from Stars Neutrinos from the Early Universe: Neutrinos as Dark Matter Neutrino Mass and Physics beyond the Standard Model CP Violation in Neutrino Mixing? Experimental Search Leptogenesis THE HUNT FOR THE MYSTERIOUS HIGGS Why We Believe in the Higgs The Standard Model Needs the Higgs Mechanism Theoretical Calculations Need the Higgs Particle What We Know from Experiment So Far Indirect Experimental Evidence for the Higgs Boson: The Importance of Virtual Effects Detecting the Higgs Boson Directly Direct Higgs Searches at LEP Direct Higgs Searches at the Tevatron What We Hope to Learn from the LHC What Is the LHC? Higgs Searches at LHC Disaster? If the LHC Cannot Find the Higgs Boson If the LHC Discovers the Higgs Boson, Is That the End of the Story? Possibilities for the Future Multi-Higgs Models The Need for Further Tests and the Importance of ILC Conclusion Appendix 1: Important Twenty-First Century Experiments Appendix 2: Renormalization, Running Coupling Constants, and Grand Unified Theories Appendix 3: Complex Numbers, Complex Fields, and Gauge Invariance Appendix 4: Unitary Matrices Appendix 5: Energy and Momentum in Special Relativity and the Uncertainty Principle
119753322
Effective monopoles within thick branes
The monopole mass is revealed to be considerably modified in the thick braneworld paradigm, and depends on the position of the monopole in the brane as well. Accordingly, the monopole radius continuously increases, leading to an unacceptable setting that can be circumvented when the brane thickness has an upper limit. Despite such peculiar behavior, the accrued quantum corrections —involving the classical monopole solution— are shown to be still under control. We analyze the monopole's peculiarities also taking into account the localization of the gauge fields. Furthermore, some additional analysis in the thick braneworld context and the similar behavior evinced by the topological string are investigated.
31431486
Flag-dipole spinor fields in ESK gravities
We consider the Riemann-Cartan geometry as a basis for the Einstein-Sciama-Kibble theory coupled to spinor fields: we focus on f(R) and conformal gravities, regarding the flag-dipole spinor fields, type-(4) spinor fields under the Lounesto classification. We study such theories in specific cases given, for instance, by cosmological scenarios: we find that in such background the Dirac equation admits solutions that are not Dirac spinor fields, but in fact the aforementioned flag-dipoles ones. These solutions are important from a theoretical perspective, as they evince that spinor fields are not necessarily determined by their dynamics, but also a discussion on their structural (algebraic) properties must be carried off. Furthermore, the phenomenological point of view is shown to be also relevant, since for isotropic Universes they circumvent the question whether spinor fields do undergo the Cosmological Principle.
56092735
Two-branes with variable tension model and the effective Newtonian constant
It is shown that, in the two brane time variation model framework, if the hidden brane tension varies according to the phenomenological Eoetvoes law, the visible brane tension behavior is such that its time derivative is negative in the past and positive after a specific time of cosmological evolution. This behavior is interpreted in terms of a useful mechanical system analog and its relation with the variation of the Newtonian (effective) gravitational ''constant'' is explored.
118401678
Searching for Elko dark matter spinors at the CERN LHC
The aim of this paper is to explore the possibility of discovering a fermionic field with mass dimension one, the Elko field, in the Large Hadron Collider. Due to its mass dimension, an Elko can only interact either with Standard Model spinors and gauge fields at one-loop order or at tree level through a quartic interaction with the Higgs field. In this Higgs portal scenario, the Elko is a viable candidate to a dark matter constituent which has been shown to be compatible with relic abundance measurements from WMAP and direct dark matter searches. We propose a search strategy for this dark matter candidate in the channel at the LHC. We show the LHC potential to discover the Elko considering a triple Higgs–Elkos coupling as small as ~0.5 after 1 ab-1 of integrated luminosity. Some phenomenological consequences of this new particle and its collider signatures are also discussed.
58918691
Probing the Supersymmetric Inflaton and Dark Matter link via the CMB, LHC and XENON1T experiments
The primordial inflation dilutes all matter except the quantum fluctuations which we see in the cosmic microwave background (CMB) radiation. Therefore the last phases of inflation must be embedded within a beyond the Standard Model (SM) sector where the inflaton can directly excite the SM quarks and leptons. In this paper we consider two inflaton candidates LLe and udd whose decay can naturally excite all the relevant degrees of freedom besides thermalizing the lightest supersymmetric particle (LSP) during and after reheating. In particular, we present the regions of the parameter space which can yield successful inflation with the right temperature anisotropy in the CMB, the observed relic density for the neutralino LSP, and the recent Higgs mass constraints from LHC within the MSSM with non-universal Higgs masses -- referred to as the NUHM2 model. We found that in most scenarios, the LSP seems strongly mass degenerated with the next to lightest LSP (NLSP) and the branching ratio B_s -> mu^+ mu^- very close to the present bound, thus leading to falsifiable predictions. Also the dark matter interactions with XENON nuclei would fall within the projected range for the XENON1T experiment. In the case of a positive signal of low scale supersymmetry at the LHC, one would be able to potentially pin down the inflaton mass by using the associated values for the mass of the stau, the stop and the neutralino.