Bulletin of the American Physical Society
APS April Meeting 2018
Volume 63, Number 4
Saturday–Tuesday, April 14–17, 2018; Columbus, Ohio
Session Y09: Axions II |
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Sponsoring Units: DPF Chair: Gianpaolo Carosi, Lawrence Livermore National Laboratory Room: A111 |
Tuesday, April 17, 2018 1:30PM - 1:42PM |
Y09.00001: Search for the axion dark matter in CULTASK Jongkuk Kim The strong CP problem, related to the lower bound of neutron EDM which is much smaller than expectations from theory, is solved by Peccei-Quinn mechanism. This mechanism invokes a new U(1) symmetry, the breakdown of which creates the axion field. When the axion mass range is below 1 meV, the hypothestical particle can also be a cold dark matter candidate. Its interaction with regular matter, other than gravitationally, is extremely weak. There have been developed a variety of methods to discover the invisible axion, and axion haloscope utilizing primakoff effect proposed by Sikivie is one of them. The CULTASK experiments are axion haloscope searches with various state-of-the-art techniques such low noise cryogenic amplifiers and strong magnetic fields that maximize the sensitivity. In this presentation, an axion search experiment in CULTASK dedicated to the axion mass range of 6.62-7.03 $\mu$eV (1.6-1.7 GHz) is presented, where the experimental key parameters are the magnetic field of 8 T, the cavity volume of about 3.5 L and the HEMT based system noise temperature of below 2 K. The upgrade plan with quantum-noise- limited superconducting amplifiers is also to be discussed. [Preview Abstract] |
Tuesday, April 17, 2018 1:42PM - 1:54PM |
Y09.00002: Multiple-cell cavity for axion dark matter search Saebyeok Ahn, Junu Jeong, Sungwoo Youn, Yannis Semertzidis Cavity-based axion dark matter experiments utilize multiple-cavity detectors, consisting of an array of identical cavities, to explore high mass regions. We introduce a new design of a pizza-cylinder type detector, characterized by multiple cells evenly divided by partitions and a narrow hollow gap in the middle of a cavity. This concept is superior to the conventional multiple-cavity design in terms of detection volume, experimental setup, and phase-matching mechanism. We present various simulation studies and an experimental demonstration to verify that this design is promising for searching for high mass axions. [Preview Abstract] |
Tuesday, April 17, 2018 1:54PM - 2:06PM |
Y09.00003: The Any Light Particle Search II (ALPS II) experiment Giuseppe Messineo The ALPS II experiment searches for weakly interacting, low mass particles such as axion-like particles (ALPs) using the “light shining through a wall” technique. A laser beam is sent through a high magnetic field region where, due to a process known as reverse Primakoff or Sikivie effect, photons can convert into ALPs. An optical barrier is set at the end of this region to prevent photons from reaching a second magnetic region where ALPs reconvert back to photons and are detected as “light shining through a wall”. To increase the number of available photons experiments usually set up high finesse optical cavities in the first magnetic region. ALPS II will take a step further and use a resonant regeneration scheme in which a second optical cavity, mode-matched and resonant with the first one, will be set up to enhance the back conversion probability of ALPs into photons. The collaboration is currently building the ALPS IIa experiment at DESY in Hamburg, Germany to test and validate the resonant regeneration concept, in preparation for a large scale experiment (ALPS IIc) that will use two 100m long cavities and 20 straightened HERA superconducting dipole magnets. I will give a general overview of the experiment and report on its current status. [Preview Abstract] |
Tuesday, April 17, 2018 2:06PM - 2:18PM |
Y09.00004: Results from a microwave cavity axion search with Phase 1 of the HAYSTAC Experiment Kelly Backes The axion is a well-motivated dark matter candidate that was first proposed as a solution to the strong CP problem. HAYSTAC is a dark matter axion experiment designed to detect cosmic axions through their conversion into photons using a high $Q$ microwave cavity detector. The platform is small but flexible to facilitate the development of new microwave cavity and amplifier concepts in an operational environment, and is the first to explore the axion model band above 10 $\mu$eV. I will discuss improvements made to the experiment between data runs one and two, and report on the results from the first phase of the experiment, covering the range 5.6--5.8\,GHz (23.15\,\textless$\, m_a $\,\textless$\,$24.0$\,\mu$eV). We exclude axion models in this mass range with two photon coupling at $\rm g_{\alpha\gamma\gamma}\,\gtrsim\,2\times10^{-14}\,$GeV$^{-1}$, which is in the upper range of the KSVZ model band. The experiment is now being upgraded with a squeezed-vacuum state receiver to improve the sensitivity and scan speed of the search. [Preview Abstract] |
Tuesday, April 17, 2018 2:18PM - 2:30PM |
Y09.00005: Phase II of the HAYSTAC Experiment Danielle Speller The Haloscope At Yale Sensitive To Axion CDM (HAYSTAC) is a tunable microwave cavity axion search experiment sensitive to significant regions of the cosmologically relevant mass range for an axion dark matter candidate. In 2017, the HAYSTAC experiment reached sensitivities of order $2\times10^{-14}$GeV$^{-1}$ in the mass range 23.15 < $m_\mathrm{a}$ < 24.0 $\mu{}$eV. This mass range is an order of magnitude higher than reached by previously existing limits. HAYSTAC is now entering the second phase of operation, incorporating the improvements from the 2017 run with a new squeezed-state receiver system and significant upgrades to the cryogenics system. We discuss the current status of the HAYSTAC experiment and the expectations for Phase II. [Preview Abstract] |
Tuesday, April 17, 2018 2:30PM - 2:42PM |
Y09.00006: Effective Approximation of Electromagnetism for Axion Haloscope Searches Younggeun Kim, Dong-Ok Kim, Junu Jeong, Yun Chang Shin, Yannis Semertzidis Most of successful experiments searching for axion dark matter are based on an anomalous coupling of axion to the electromagnetic field. This requires a modification of the classical Maxwell equations to include the anomalous interaction. However, due to the axion anomaly, this set of modified Maxwell equations doesn't naturally satisfy certain boundary conditions such as one for axion haloscope searches. We introduce an effective approximation of Maxwell equations to resolve this issue and shows that they naturally satisfy the boundary conditions for haloscope searches. The electric stored energy and magnetic stored energy are also estimated from the electromagnetic fields, which are different in this approximation. A very small difference arises between the electric and magnetic stored energies due to the anomalous interaction. The difference can be interpreted as oscillating electric dipole moments (EDM) induced by axions. [Preview Abstract] |
Tuesday, April 17, 2018 2:42PM - 2:54PM |
Y09.00007: Effects of Gravity on Dense Nonrelativistic Axions Eric Braaten, Abhishek Mohapatra, Hong Zhang Previous studies of dense gravitating systems of axions (or any bosons described by a real scalar field) have assumed that the effects of gravity are produced by the gravitational potential whose source is the energy density of the bosons. However the oscillations of a real scalar field necessarily produces a pressure that is instantaneously comparable in magnitude to the energy density, although its average over an oscillation period may be much smaller. When the pressure is taken into account in Einstein's equation in the weak gravity limit, the effects of gravity are produced by two gravity potentials, one whose source is the energy density and the other whose source is the pressure. The pressure may have a significant effect on dense gravitating systems of nonrelativistic bosons, such as a collapsing dilute axion star or a dense axion star. [Preview Abstract] |
Tuesday, April 17, 2018 2:54PM - 3:06PM |
Y09.00008: Nonrelativistic Effective Field Theory for the Axion in General Relativity Abhishek Mohapatra, Eric Braaten, Hong Zhang A nonrelativistic effective field theory (EFT) can be obtained from a relativistic field theory by integrating out fluctuations of the field with 4-momenta of the order mass $m$. If the field has gravitational interactions, then fluctuations of the space-time metric with 4-momenta of order $m$ must also be integrated out. Given the Lagrangian for the nonrelativistic EFT in the absence of gravity, we can use general coordinate invariance to deduce the effective Lagrangian for the gravitationally interacting field. The nonrelativistic EFT for a real Lorentz-scalar field is a field theory with a complex field. In this talk, I use general coordinate invariance to derive the EFT for the gravitationally interacting complex field. A physically relevant application of this EFT is axion stars, which are gravitationally bound Bose-Einstein condensates of axions. [Preview Abstract] |
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