Speaker: Dr. Mike Tarbutt, Centre for Cold Matter, Department of Physics, Imperial College London
Time/Location: 2:30 pm, Thursday, March 2, Pupin 705
Title: "Laser cooling and magneto-optical trapping of molecules"
Ultracold molecules are desirable for many applications, including tests of fundamental physics, studies of strongly-interacting many-body quantum systems, quantum simulation and information processing, and ultracold chemistry. Direct laser cooling is difficult for molecules because of the many vibrational states that need to be addressed. I will present our recent work on Doppler cooling, sub-Doppler cooling, and magneto-optical trapping of diatomic molecules, and will explain how this new capability will be useful for quantum science, quantum technology, and fundamental physics.
To date, the CMB has been our cleanest probe of the physics of the early universe. It is in principle limited in its information content. In the first part of the talk, we survey the prospects for gains in our theoretical understanding of the early universe from exhausting observations of temperature and polarization anisotropies (and possibly measuring spectral distortions) in the near to mid term.
In the second part, we present an amusing observation that the CMB can be used to bound (possibly even count) the hidden field content of the universe, since a large number of (non-conformally coupled) hidden fields can resum to potentially observable logarithmic runnings in CMB observables in the context of single field inflation, courtesy of a `large N' expansion. Thus, one can convert ever more precise bounds on absence of such effects into bounds on the hidden field content of the universe, with marginally interesting implications for various phenomenological constructions.
Please join us Monday, March 6, 2017, as David Spergel of the Simons Foundation gives his colloquium:
"Cosmology: The Next Ten Years"
Cosmology now has a standard model that fits a host of astronomical data. However, this model requires novel physics to explain cosmic acceleration, dark matter, and the origin of the universe. As our data improves, intriguing discrepancies are starting to arise. The Planck experiment is inferring a value for the Hubble constant that does not appear to be consistent with local distance ladder measurements or geometric measurements based on gravitational lensing. I will discuss how upcoming experiments will clarify the properties of dark energy and test our standard cosmology. I will focus on the next generation of microwave background experiments and NASA’s Wide Field Infrared Space Telescope (WFIRST).
About the speaker
David Spergel joined the foundation in 2016 to lead its Center for Computational Astrophysics. He is an astrophysicist with research interests ranging from the search for planets around nearby stars to the shape of the universe. Using microwave background observations from the Wilkinson Microwave Anisotropy Probe and the Atacama Cosmology Telescope, he has measured the age, shape and composition of the universe; these observations have played a significant role in establishing the standard model of cosmology. Prior to joining the foundation, Spergel was chair of the department of astrophysical sciences at Princeton University, and he is currently an associate faculty member in the university’s physics department and in the mechanical and aerospace engineering department. Spergel is a MacArthur fellow, a fellow of the American Physical Society and a member of both the National Academy of Sciences and the American Academy of Arts and Sciences. He was a recipient of the Gruber Prize in 2012 and the Shaw Prize in 2010 for his work on cosmology.
I will review and develop the general properties of L∞ algebras focusing on the gauge structure of the associated field theories. Since these algebras also capture the structure of interactions, it is plausible that they can provide a classification of gauge invariant perturbative field theories.
Nature is one of the world's leading scientific journals, publishing many papers that receive wide attention by the general public. But, Nature is very selective-- <7% of submitted papers are published. In order to maximize your chances of getting published, papers should present fundamental new physical insights, or startling observations/results. Theory papers pose additional problems, as we want only those papers that are likely to be the correct explanation, and not simply exploring parameter space. The writing should be clear, concise and directed at the level of a graduate course in the subject. I encourage authors to contact me in advance of submission of a paper, both to ascertain the appropriateness of the result for Nature, and to ensure that the writing is close to our standards. Posting to ArXiv is and always has been allowed, but authors should discuss the specifics with their institutional public affairs officers before doing so.
About the speaker
Leslie Sage is Senior Editor, Physical Sciences, at Nature. Leslie received his PhD in Astronomy at Stony Brook University. His research is generally in the area of gas content and star formation in other galaxies, based on observations of HI, CO and other molecular tracers.
The Weak Gravity Conjecture (WGC), in its original form, says that given an abelian gauge theory there should be at least one charged particle whose charge is bigger than its mass in Planck units. I will argue that the evidence we have suggests a much stronger conjecture, which requires towers of charged particles in infinitely many representations of the gauge group. This stronger conjecture leads to low ultraviolet cutoffs on theories with very weakly coupled gauge fields. I will discuss some possible phenomenological applications of the stronger conjecture.
Astrophysical observations give overwhelming evidence for the existence of dark matter. And yet we do not know what it is. Two candidates, axions and WIMPs, are the subjects of current active research. Direct detection dark matter experiments designed to detect WIMPs have made enormous progress in the past 30 years, however no clear signal has been observed. In this context, the DAMA collaboration has asserted for over 15 years that they observe a dark matter-induced annual modulation signal. Their observation has yet to be confirmed. I will describe the current efforts in testing DAMA’s claim for detection, in particular, I will present COSINE-100 and DM-Ice. COSINE-100, a joint experiment between the DM-Ice and KIMS collaboration, is a 100-kg scale experiment capable of testing DAMA, currently in operation at the Yangyang Underground Laboratory in South Korea. DM-Ice is a low-background NaI(Tl)-based dark matter experiment aimed at understanding the DAMA signal and unambiguously testing the hypothesis of a dark-matter induced annual modulation signal. DM-Ice17, a prototype experiment consisting of 17kg of NaI(Tl) detectors, has been continuously operating at the South Pole since 2011. The status of the field, including results from DM-Ice17 and what we can expect from COSINE-100 and DM-Ice will be presented.
About the speaker
Professor Reina Maruyama is exploring new physics in nuclear and particle astrophysics, in particular, in dark matter and neutrinos. Her group is carrying out direct detection of dark matter experiments in terrestrial-based detectors and searches for neutrinoless double beta decay. The current experiments include COSINE-100 located at the Yangyang Underground Laboratory in South Korea, DM-Ice, and IceCube located at the South Pole, and CUORE, located at Gran Sasso, Italy.