Bulletin of the American Physical Society
APS April Meeting 2021
Volume 66, Number 5
Saturday–Tuesday, April 17–20, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session T14: Nuclear Theory ILive
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Sponsoring Units: DNP Chair: Diego Lonardoni, NSCL and Michigan State University |
Monday, April 19, 2021 3:45PM - 3:57PM Live |
T14.00001: Dark Matter-Nucleon interaction in the Large-N Limit Xincheng Lin, Son Nguyen, Thomas Richardson We study the contact interactions between nucleons and spin-$\frac{1}{2}$ or scalar dark-matter (DM) particles in the framework of pionless effective field theory (EFT$_{\cancel{\pi}}$). The relatives size of low energy coefficients (LECs) is estimated in the large $N_c$ limit, where $N_c$ is the number of colors in quantum chromodynamics (QCD). We also study deuteron-DM elastic scattering and compute the Helium-3/triton-DM cross section to leading-order (LO) in EFT$_{\cancel{\pi}}$ and next-to-leading-order (NLO) in $1/N_c$. The numerical upper bound is obtained by applying cosmological constraints on LECs. [Preview Abstract] |
Monday, April 19, 2021 3:57PM - 4:09PM Live |
T14.00002: Quantum Monte Carlo calculation of partial muon capture rates Garrett King, Saori Pastore, Maria Piarulli Searches for neutrinoless-double beta ($0\nu\beta\beta$) decay rates are crucial in addressing questions within fundamental symmetries and neutrino physics. The rates of these decays depend not only on unknown parameters associated with neutrinos, but also on nuclear properties. In order to reliably extract information about the neutrino, one needs an accurate treatment of the complex many-body dynamics of the nucleus. Recently, quantum Monte Carlo calculations of Gamow-Teller matrix elements using the Norfolk potential, a high-quality local chiral interaction containing two- and three-body forces, and its set of consistent one- and two-body axial current operators provided model validation at low momentum transfer. $0\nu\beta\beta$ decays take place at momentum transfers on the order of 100 MeV and require both vector and axial current operators. Muon capture, a process in the same momentum transfer regime, has readily available experimental data to validate both axial and vector electroweak current operators. In this work, we present the results of {\it ab initio} calculations of muon capture in $A \le 12$ nuclei using variational and Green's Function Monte Carlo wave functions. [Preview Abstract] |
Monday, April 19, 2021 4:09PM - 4:21PM Live |
T14.00003: Eigenvector Continuation Emulators for NN Scattering A.J. Garcia, R.J. Furnstahl, P.J. Millican, Xilin Zhang The computational expense of full uncertainty quantification for low-energy nuclear calculations motivates the development of emulators. Recent work has shown that eigenvector continuation (EC) can be used to build efficient emulators for both bound state and scattering observables. EC is a variational technique that uses eigensolutions for several sets of known parameters to form a basis that can be used to accurately interpolate and extrapolate solutions for the same Hamiltonian with different parameters. Here we apply and test EC for the nucleon-nucleon (NN) scattering problem using a variety of chiral effective field theory potentials formulated in both coordinate and momentum space. [Preview Abstract] |
Monday, April 19, 2021 4:21PM - 4:33PM Live |
T14.00004: Dalitz plots and lineshape of a1(1260) through a three-body unitary approach Daniel SADASIVAN, Maxim Mai, Hakan Akdag, Michael Doering We present our formulation of the final-state interaction of the $a_1(1260)$ resonance decay in a manifestly three-body unitary parameterization and fit it to the $a_1(1260)$ lineshape measured by the ALEPH experiment. Dalitz plots calculated from this fit are presented. The work demonstrates the feasibility to numerically solve a previously derived amplitude and its generalization to isobars with spin and coupled channels. The model can also be applied to other meson decays and modified for the finite-volume problem as it arises in lattice QCD due to its manifest unitarity. [Preview Abstract] |
Monday, April 19, 2021 4:33PM - 4:45PM Live |
T14.00005: Electric polarizability of hadrons from Lattice QCD Hossein Niyazi, Andrei Alexandru, Frank Lee Electric and magnetic polarizabilities are two of the fundamental properties of hadrons which help us understand the distribution of charge and currents inside hadrons and how they respond to external electromagnetic fields. For nucleons, these values are determined experimentally from Compton scattering. For charged pions, the experiments are more challenging since no free pion target is available and the results are less precise, but a number of experiments are planned that will improve the accuracy. Lattice QCD can be used to compute hadron properties as determined by quark and gluon dynamics, providing results that are complementary to other theoretical approaches. In this talk I will review the lattice QCD methods used to compute hadron polarizabilities, focusing on electric polarizability, and present our results. [Preview Abstract] |
Monday, April 19, 2021 4:45PM - 4:57PM Live |
T14.00006: Energy-momentum tensor and D-term in the presence of electromagnetic long-range forces Mira Varma, Peter Schweitzer The prospects of accessing information on the hadronic form factors of the energy-momentum tensor (EMT) have attracted a lot of interest in literature. This concerns especially the D-term form factor D(t) with its appealing interpretation in terms of internal forces. With the focus on hadron structure, so far theoretical and model studies concentrated on strongly interacting systems with short-range forces. Not considered so far were long-range forces like electromagnetic interaction, which is thought to play a negligible role for the balance of forces inside the proton. But the long-range nature of electromagnetic forces introduces features that were not encountered before. We use a case study in a classical model of the proton to show how the presence of long-range forces alters some notions which can be taken for granted in short-range systems. The important conclusion is that a more careful definition of the D-term may be required when long-range forces are present. [Preview Abstract] |
Monday, April 19, 2021 4:57PM - 5:09PM Live |
T14.00007: Constraining gluon momentum and spin distributions from jet observables Yiyu Zhou, Nobuo Sato, Wally Melnitchouk We made simultaneous extraction of spin averaged and spin dependent PDFs within multistep MC procedures, with combined analysis of inclusive unpolarized and polarized Jet from RHIC to Tevatron energies. By analyzing the preliminary results we had, we were able to further constrain on $\Delta g$. [Preview Abstract] |
Monday, April 19, 2021 5:09PM - 5:21PM Not Participating |
T14.00008: The limit $\xi \rightarrow 0$ of the GPD $\widetilde{E}$. Philip Velie, Simonetta Liuti The GPD $\widetilde{E}$ integrates to the pseudoscalar form factor of the nucleon, $g_P$ which, due to the spontaneously broken chiral symmetry, is dominated by the contribution of a pion pole at low momentum transfer squared, $t$. The GPD $\widetilde{E}$ , allow us, therefore, to study the pseudoscalar content of the nucleon at the partonic level. In particular, we discuss the limit $\xi \rightarrow 0$ of the skewness parameter. [Preview Abstract] |
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