Bulletin of the American Physical Society
APS April Meeting 2017
Volume 62, Number 1
Saturday–Tuesday, January 28–31, 2017; Washington, DC
Session X10: Particle and Gravity Theory I |
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Sponsoring Units: DPF Chair: Geoffrey Lovelace, Cal State Fullerton Room: Roosevelt 2 |
Tuesday, January 31, 2017 10:45AM - 10:57AM |
X10.00001: Supersymmetric SO(10) Inflation Qaisar Shafi, George Leontaris, Nobuchika Okada We describe how $\lambda \phi^4$ inflation with non-minimal coupling to gravity is realized in realistic supersymmetric $SO(10)$ models. In a well-motivated example the $16-\overline{16}$ Higgs multiplets, which break $SO(10)$ to $SU(5)$ and yield masses for the right handed neutrinos, provide the inflaton field $\phi$. Thus, leptogenesis is a natural outcome in this class of SO(10) models. Moreover, the adjoint (45-plet) Higgs also acquires a GUT scale value during inflation so that the monopole problem is evaded. The scalar spectral index $n_s$ is in good agreement with the observations and $r$, the tensor to scalar ratio, is predicted for realistic values of GUT paramters to lie close to 0.003. [Preview Abstract] |
Tuesday, January 31, 2017 10:57AM - 11:09AM |
X10.00002: Conversion of Chern-Simons Number to Electromagnetic Helicity Yiyang Zhang, Francesc Ferrer, Tanmay Vachaspati Non-perturbative electroweak processes accessible in the early universe are known to violate baryon plus lepton number, which may give a clue on the cosmic matter-antimatter asymmetry. The associated change in Chern-Simons number has been related to the generation of helical magnetic fields. We study the full dynamics of the Higgs field and the electroweak gauge fields during the electroweak phase transition. Specifically, we set up a pure gauge SU(2) configuration with non-trivial winding in a region with vanishing Higgs field. By numerically evolving the classical equations of motion in the lattice, we confirm that the phase transition results in a change of Chern-Simons number and the generation of a helical magnetic field. The magnitude of the change of Chern-Simons number and magnetic helicity depend on the initial conditions. [Preview Abstract] |
Tuesday, January 31, 2017 11:09AM - 11:21AM |
X10.00003: Einstein-Yang-Mills-Dirac systems from the discretized Kaluza-Klein theory Kameshwar Wali, Nguyen Ali Viet A unified theory of the non-Abelian gauge interactions with gravity in the framework of a discretized Kaluza-Klein theory is constructed with a modified Dirac operator and wedge product. All the couplings of chiral spinors to the non-Abelian gauge fields emerge naturally as components of the coupling of the chiral spinors in the generalized gravity together with some new interactions. In particular, the currently prevailing gravity-QCD quark and gravity-electroweak-quark and lepton models are shown to follow as special cases of the general framework. [Preview Abstract] |
Tuesday, January 31, 2017 11:21AM - 11:33AM |
X10.00004: Experimental test methods of a unified theory of fundamental interactions Xiao-Fan Chen Experimental test methods of a new theory of gravitation and a unified theory of four basic interactions are discussed. In the new theories of gravity and unification, gravitation can be quantized and renormalized. [Preview Abstract] |
Tuesday, January 31, 2017 11:33AM - 11:45AM |
X10.00005: Supersymmetry Properties of AdS Supergravity Backgrounds Samuel Beck, Jan Gutowski, George Papadopoulos Anti-de Sitter supergravity backgrounds are of particular interest in light of the AdS/CFT correspondence, which relates them to dual conformal field theories on the boundary of the anti-de Sitter space. We have investigated the forms of the supersymmetries these backgrounds preserve by solving the Killing spinor equations on the anti-de Sitter components of these spaces. We have found that a supersymmetric AdS$_n$ background necessarily preserves $2^{\lfloor{n\over2}\rfloor} k$ supersymmetries for $n \leq 4$ and $2^{\lfloor{n\over2}\rfloor+1} k$ supersymmetries for $4< n \leq 7$, $k \in \bb{N}_{>0}$. Additionally, we have found that the Killing spinors of each background are exactly the zeroes of a Dirac-like operator constructed from the Killing spinor equations. [Preview Abstract] |
Tuesday, January 31, 2017 11:45AM - 11:57AM |
X10.00006: Integrand Reduction Reloaded: Algebraic Geometry and Finite Fields Ray D. Sameshima, Andrea Ferroglia, Giovanni Ossola The evaluation of scattering amplitudes in quantum field theory allows us to compare the phenomenological prediction of particle theory with the measurement at collider experiments. The study of scattering amplitudes, in terms of their symmetries and analytic properties, provides a theoretical framework to develop techniques and efficient algorithms for the evaluation of physical cross sections and differential distributions. Tree-level calculations have been known for a long time. Loop amplitudes, which are needed to reduce the theoretical uncertainty, are more challenging since they involve a large number of Feynman diagrams, expressed as integrals of rational functions. At one-loop, the problem has been solved thanks to the combined effect of integrand reduction, such as the OPP method, and unitarity. However, plenty of work is still needed at higher orders, starting with the two-loop case. Recently, integrand reduction has been revisited using algebraic geometry. In this presentation, we review the salient features of integrand reduction for dimensionally regulated Feynman integrals, and describe an interesting technique for their reduction based on multivariate polynomial division. We also show a novel approach to improve its efficiency by introducing finite fields. [Preview Abstract] |
Tuesday, January 31, 2017 11:57AM - 12:09PM |
X10.00007: Implementation of Recursion Relations in Gluon Scattering Amplitude Calculations in $\text{AdS}_4/\text{CFT}_3$ Nikolaos Dokmetzoglou, Savan Kharel The Anti-de Sitter/Conformal Field Theory (AdS/CFT) correspondence is a duality between a theory of gravity in curved-space (AdS) and a conformally-invariant quantum field theory in flat-space (CFT). Scattering amplitudes are observables associated with the probability of the interaction of a given assembly of particles. Gluons, being the exchange particles associated with the strong nuclear force, which holds quarks together to form protons, are abundant byproducts of fundamental particle collisions. Thus, studying gluon scattering amplitudes is an effective way of deepening our understanding of these observables in AdS/CFT. Traditionally, Feynman diagrams have been used to calculate such scattering amplitudes. In this project, we use factorization properties and recursion relations to simplify these calculations. More specifically, we calculate multiple (different helicity combinations) four-point gluon scattering amplitudes in $\text{AdS}_4/\text{CFT}_3$ (4-D AdS and 3-D CFT) as sums of products of three-point amplitudes. And then we calculate a five-point gluon scattering amplitude in $\text{AdS}_4/\text{CFT}_3$ by decomposing it into a sum of products of these four-point and three-point amplitudes. Finally we comment on useful identities for checking these amplitudes. [Preview Abstract] |
Tuesday, January 31, 2017 12:09PM - 12:21PM |
X10.00008: Dimensionless actions in four dimensions and Einstein gravity Ariel Edery, Yu Nakayama Recently, it has been pointed out that dimensionless actions in four dimensional curved spacetime possess a symmetry which goes beyond scale invariance but is smaller than full Weyl invariance. This symmetry was dubbed restricted Weyl invariance. We show that starting with a restricted Weyl invariant action that includes pure $R^2$ gravity and a Higgs sector with no explicit mass, one can generate the Einstein-Hilbert action with cosmological constant and a Higgs mass. The model also contains an extra massless scalar field which couples to the Higgs field (and gravity). If the coupling of this extra scalar field to the Higgs field is negligibly small, this fixes the coefficient of the nonminimal coupling between the Higgs field and gravity [Preview Abstract] |
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