Bulletin of the American Physical Society
APS April Meeting 2019
Volume 64, Number 3
Saturday–Tuesday, April 13–16, 2019; Denver, Colorado
Session H13: Particle & Fields Theory I |
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Sponsoring Units: DPF Chair: Steve Sekula Room: Sheraton Plaza Court 2 |
Sunday, April 14, 2019 10:45AM - 10:57AM |
H13.00001: Instanton Triggered Chiral Symmetry Breaking and the Strong CP Problem William A Bardeen I develop a new picture of the role that instantons play in the explicit and spontaneous breaking of quark chiral symmetries in the Standard Model of particle physics. I will show how small instantons can generate an apparent mass for a massless up quark as possible solution to the strong CP problem. |
Sunday, April 14, 2019 10:57AM - 11:09AM |
H13.00002: Two natural scenarios for dark matter particles coexisting with supersymmetry Roland E Allen, Maxwell Throm, Reagan Thornberry, John D Killough, Brian Sun, Gentill Abdulla We describe two natural scenarios in which both dark matter WIMPs (weakly interacting massive particles) and a variety of supersymmetric partners should be discovered in the foreseeable future. In the first scenario, the WIMPs are neutralinos, but they are only one component of the dark matter, which is dominantly composed of other relic particles such as axions. (This is the multicomponent model of Baer, Barger, Sengupta, and Tata.) In the second scenario, the WIMPs result from an extended Higgs sector and may be the only dark matter component. In either scenario, both the dark matter WIMP and a plethora of other neutral and charged particles await discovery at many experimental facilities. The new particles in the second scenario have far weaker cross-sections for direct and indirect detection via their gauge interactions, which are either momentum-dependent or second-order. However, they should have much stronger interactions via the Higgs. We estimate that their interactions with fermions will then be comparable to (although not equal to) those of neutralinos with a corresponding Higgs interaction. It follows that these newly proposed dark matter particles should be within reach of emerging and proposed facilities for direct, indirect, and collider-based detection. |
Sunday, April 14, 2019 11:09AM - 11:21AM |
H13.00003: Soft-gluon corrections for t gamma production via anomalous couplings Matthew Forslund, Nikolaos Kidonakis We present results for higher order soft-gluon corrections for t gamma production via anomalous t-q-gamma couplings, with q an up quark or a charm quark. We provide results for the total cross sections and differential distributions at LHC energies. We use K-factors to show the significance of the corrections compared to leading order and discuss the importance of the results. |
Sunday, April 14, 2019 11:21AM - 11:33AM |
H13.00004: Off-shell t-channel single-top-quark production at next-to-leading order in QCD in a Standard Model Effective Field Theory Zack E Sullivan, Tobias Neumann We present the fully differential next-to-leading order (NLO) QCD calculation of t-channel single-top-quark production including off-shell effects in the complex mass scheme, and corrections from new operators arising from a Standard Model Effective Field Theory (SMEFT). We include all relevant SMEFT operators at 1/Lambda^{2} that contribute at NLO in QCD, as well as operators that contribute only at 1/Lambda^{4} that do not interfere with the Standard Model. This expansion allows for a systematic theoretical treatment of physics Beyond the Standard Model, and places context around phenomenologically motivated anomalous right- and left-handed Wtb vector and tensor couplings. |
Sunday, April 14, 2019 11:33AM - 11:45AM |
H13.00005: A determination of the weak neutral-current axial-vector form factor Raza Sufian, Keh-Fei Liu, David G Richards We use a combination of lattice QCD calculations of the strange-quark electromagnetic form factors and a phenomenological parametrization of the F_{1}and F_{2} electromagnetic form factors, to obtain the weak neutral-current axial form factor from a fit to MiniBooNE and BNL (anti)-neutrino-nucleon elastic scattering differential cross-section data. We thereby obtain a value for the weak axial charge, and the strange-quark contribution to the proton spin. We conclude with prospects for fully ab initial calculations of the form factor within lattice QCD. |
Sunday, April 14, 2019 11:45AM - 11:57AM |
H13.00006: SU(2) Charges with Spherical Symmetry and Confining Boundary Conditions Dennis W Sivers The field-strength description for a simple system of static SU(2) charges with spherical symmetry and confining boundary conditions is studied using the Yang-Mills Maxwell equations. Three types of solutions are identified. Type-0 solutions are unstable with respect to small fluctuations. Type-1 solutions involve a domain wall of topological charge and an exterior volume resembling a condensate of magnetic charge. Type-2 solutions have a domain wall of topological charge and a sterile field-free exterior volume with vacuum quantum numbers. In analogy to the kink solution for the 1+1 dimensional Abelian Higgs model we argue that the type-2 solutions should contain a mass gap. |
Sunday, April 14, 2019 11:57AM - 12:09PM |
H13.00007: Magnetic Vortices in Finite Isospin Chiral Perturbation Theory Prabal Adhikari We study magnetic vortices in finite isospin chiral perturbation theory, the effective theory of low energy QCD. The relevant degrees of freedom in chiral perturbation theory are three pions (two of which are electromagnetically charged) that arise due to spontaneous breaking of chiral symmetry by the QCD vacuum. Since pions are Goldstone bosons, interactions between them are derivative in nature. At zero external magnetic field, above a critical chemical potential charged pions form a superfluid. In the presence of a uniform, external magnetic field, we show that pions behave as type-II superconductors. We find the magnetic vortex lattice condensation energy and the vortex lattice structure near the upper critical point, and construct the phase diagram by finding the critical magnetic fields as a function of the isospin chemical potential. We also discuss the possibility of neutral pion condensation, which do not couple directly with the external magnetic field but couple with the charged pions via strong interactions. |
Sunday, April 14, 2019 12:09PM - 12:21PM |
H13.00008: The anomalous effective action as an ideal fluid Andrey Sadofyev The anomalous sector of QED can be described with an effective action involving two pseudoscalar degrees of freedom. We show that this action supplemented with an equilibrium energy density describes a quantum fluid. Using this EFT we show that the commutation relation originating in the corresponding Hamiltonian formalism reproduces the anomalous commutators of the current algebra. We re-derive the anomalous transport within this formalism in 4d and 2d QED. In 2d case we show that the action of this anomalous fluid is in one-to-one correspondence with the bosonized action of the Schwinger model. |
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