122201296
ELKO SPINOR FIELDS AS A TOOL FOR PROBING EXOTIC TOPOLOGICAL SPACETIME FEATURES
We report about some achievements and developments provided by the ELKO program, in particular the ones recently accomplished.1 Exotic dark spinor fields has been investigated in the context of inequivalent spin structures on arbitrary curved spacetimes, which induces an additional term on the associated Dirac operator, related to a Cech cohomology class. Exotic terms operating on standard model Dirac spinor fields are usually absorbed by gauge transformations encoded as a shift of some vector potential representing an element of the cohomology group H1(M, ℤ2). That is not the case of ELKO, once they cannot carry gauge charge. As a consequence, the ELKO program requires a complete evaluation of topological analysis. Since exotic dark spinor fields also satisfy Klein-Gordon propagators, the dynamical constraints related to the exotic term in the Dirac equation can be explicitly computed. It forthwith implies that the non-trivial topology associated to the spacetime can drastically engender — from the dynamics of dark spinor fields — constraints on the spacetime metric structure. Besides being candidates to the dark matter problem, dark spinor fields are shown to be potential candidates to probe non-trivial topologies in spacetime, as well as to explain the spacetime metric structure.
119686824
Regular Bulk Solutions and Black Strings from Dynamical Braneworlds with Variable Tension
Regular black strings solutions associated to a dynamical Friedmann-Robertson-Walker braneworld are obtained as a particular case of a regular bulk metric, in the context of a variable brane tension. By analyzing the 5D Kretschmann invariants, we show that the variable brane tension is capable to remove bulk singularities, along some eras of the evolution of the Universe. In particular, the black string time-dependent profile in the bulk is analyzed in the context of the McVittie metric on an E\"otv\"os fluid braneworld, wherein the fluid dynamical brane tension depends on the brane temperature. The whole bulk is shown to be regular for a Universe dominated by non-relativistic matter or by relativistic matter/radiation, as the cosmological time elapses. In a particular case the associated black strings are shown to have finite extension along the extra dimension, what prominently modify the higher-dimensional physical singularities. For a Universe dominated by matter or radiation, we show that the brane singularities are removed along the extra dimension, as an effect of the variable brane tension, corresponding also to the vanishing of the black string horizon. In this case there is a regular solution in the bulk. We show further that no additional physical singularity is introduced in the bulk when the Universe is dominated by a cosmological constant.
117828168
Possible Generalizations within Braneworld Scenarios: Torsion fields
In this Chapter we introduce the aspects in which torsion can influence the formalism of braneworld scenarios in general, and also how it is possible to measure such kind of effects, namely, for instance, the blackstring transverse area corrections and variation of quasar luminosity due to those corrections. We analyze the projected effective Einstein equation in a 4-dimensional arbitrary manifold embedded in a 5-dimensional Riemann-Cartan manifold. The Israel-Darmois matching conditions are investigated, in the context where the torsion discontinuity is orthogonal to the brane. Unexpectedly, the presence of torsion terms in the connection does not modify such conditions whatsoever, despite of the modification in the extrinsic curvature and in the connection. Then, by imposing the Z2-symmetry, the Einstein equation obtained via Gauss-Codazzi formalism is extended, in order to now encompass the torsion terms. We also show that the factors involving contorsion change drastically the effective Einstein equation on the brane, as well as the effective cosmological constant. Also, we present gravitational aspects of braneworld models endowed with torsion terms both in the bulk and on the brane. In order to investigate a conceivable and measurable gravitational effect, arising genuinely from bulk torsion terms, we analyze the variation in the black hole area by the presence of torsion. Furthermore, we extend the well known results about consistency conditions in a framework that incorporates brane torsion terms. It is shown, in a rough estimate, that the resulting effects are generally suppressed by the internal space volume.
119652642
Black holes in realistic branes: Black string-like objects?
Abstract A realistic model describing a black string-like object in an expanding Universe is analyzed in the context of the McVittieʼs solution of the Einstein field equations. The bulk metric near the brane is provided analogously to previous solutions for black strings. In particular, we show that at least when the Hubble parameter on the brane is positive, a black string-like object seems to play a fundamental role in the braneworld scenario, generalizing the standard black strings in the context of a dynamical brane.
56078295
Towards a hybrid compactification with a scalar–tensor global cosmic string
We derive a solution of the gravitational equations which leads to a braneworld scenario in six dimensions, using a global cosmic string solution in a low energy effective string theory framework. The final spacetime is composed by one warped brane with topology and a power law warp factor, and one non-compact extra dimension transverse to the brane; by looking at the current experimental bounds, we find a range of parameters in which, if the on-brane dimension has an acceptable size, it does not solve the hierarchy problem. In another example, this problem is smoothed by means of the Brans–Dicke parameter.
118609176
Static domain wall in braneworld gravity
In this paper we consider a static domain wall inside a 3-brane. Different from the standard achievement obtained in General Relativity, the analysis performed here gives a consistency condition for the existence of static domain walls in a braneworld gravitational scenario. Also the behavior of the domain wall’s gravitational field in the newtonian limit is shown.
8371193
Measurements of new physics in B -> pi pi decays
If new physics (NP) is present in B -> pi pi decays, it can affect the isospin I=2 or I=0 channels. In this paper, we discuss various methods for detecting and measuring this NP. The techniques have increasing amounts of theoretical hadronic input. If NP is eventually detected in B -> pi pi -- there is no evidence for it at present -- one will be able to distinguish I=2 and I=0, and measure its parameters, using these methods.
55840509
The 125 GeV Higgs in the NMSSM in light of LHC results and astrophysics constraints
Daniel Albornoz Vásquez,1 Geneviève Bélanger,2 Céline Bœhm,3, 2 Jonathan Da Silva,2, 3 Peter Richardson,3 and Chris Wymant3 1Institut d’Astrophysique de Paris, UMR 7095 CNRS, Université Pierre et Marie Curie, 98 bis Boulevard Arago, Paris 75014, France 2LAPTH, U. de Savoie, CNRS, BP 110, 74941 Annecy-Le-Vieux, France. 3Institute for Particle Physics Phenomenology, University of Durham, Durham, DH1 3LE, UK
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
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.
118619942
The right-handed sneutrino as thermal dark matter in U(1) extensions of the MSSM
We investigate the parameter space of a supersymmetric model with an extended U(1) gauge symmetry in which the RH sneutrino is a thermal dark matter candidate. In this scenario, annihilation of RH sneutrinos proceeds mainly through Higgs or Z' exchange. We find that sneutrinos in the mass range from 50 GeV to more than 1 TeV can be consistent with both the WMAP limit and the direct detection upper limits. Powerful constraints from new gauge boson searches at the LHC as well as from ΔMs are incorporated. Depending on the choice of the U(1) charge, these scenarios will be further probe by direct dark matter searches as well as by Higgs searches at the LHC.