Speaker: Graham Kribs
Title: Seeing the Light of Dark Matter
Host: John Terning
Zoom: https://zoom.us/j/186024391
Abstract: The entire Earth will be utilized as a scattering medium to excite inelastic dark matter that will be shown to be detectable by its decay to a photon in large underground detectors. Along the way we'll have fun learning some planetary geochemistry, "useful" astrology, and the potential of future gas scintillator direct detection experiments.
A major success of the physics program at the Relativistic Heavy Ion Collider (RHIC) was the indentification of evidence confirming the creation of a Quark-Gluon Plasma (QGP) state of matter in heavy-ion collisions. What remains as an open question is the nature of the phase tranistion between the QGP and the hadronic gas to which it transitions as it cools in the aftermath of the collision. We now understand that when a QGP which contains equal numbers of quarks and anti-quarks (such as after the big bang) cools the phase transition is continous. Theory predicts that as the ratio of quark to anti-quarks
skews significantly, as is the case in lower energy heavy-ion collisions, the phase transition will become first-order. Preliminary results from an energy scan of Au+Au collisions at RHIC suggested that such a transistion was occuring, but the results were not definative. RHIC is currently in the middle of a three-year program to answer this question. Thus talk will review the upgrades to the STAR detector at RHIC and to the collider necessary for this study, the status of the program, and the preliminary results.
User:
High-Energy Seminars
Time:
1:30pm - 2:30pm
Send Reminder:
Yes - 0 days 4 hour 0 minutes before start
Description:
Speaker: Hajime Fukuda
Title:Aspects of Nonlinear Effect on Black Hole Superradiance
Host: Da Liu
Zoom: https://zoom.us/j/186024391
Abstract:
Under some conditions, light boson fields grow exponentially
around a rotating black hole, called the superradiance instability. We
discuss effects of nonlinear interactions of the boson on the
instability. In particular, we focus on the effect of the particle
production and show that the growth of the boson cloud may be
saturated much before the black hole spin is extracted by the boson
cloud, while the nonlinear interactions also induce the boson
emission. For application, we revisit the superradiant instability of
the standard model photon, axion and hidden photon.
User:
High-Energy Seminars
Time:
4:10pm - 5:00pm
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Yes - 0 days 4 hour 0 minutes before start
Description:
Speaker: Dr. Jingbo Wang
Title: Exploring Neutrino Physics with DUNE
Location: https://ucdavis.zoom.us/j/6874958832?pwd=YkRNRkY0eFcyUm14aCtaWGRxVGdPUT09
User:
High-Energy Seminars
Time:
1:30pm - 2:30pm
Send Reminder:
Yes - 0 days 4 hour 0 minutes before start
Description:
Speaker: R. Sekhar Chivukula
Title:Scattering Amplitudes and Sum Rules for Massive Spin-2 States
Host: Da Liu
Zoom: https://zoom.us/j/186024391
Abstract:
Spin-2 Kaluza-Klein states arise in many theoretical contexts, from string theory and AdS/CFT to phenomenological models of particle physics and dark matter; they are also the focus of experimental searches at the LHC. A key question that influences their phenomenology and the range of validity of any effective field theories built around them is how quickly scattering amplitudes involving these modes grow with energy. The faster they grow, the lower the energy at which the amplitudes violate partial-wave unitarity, rendering the theory inconsistent. We have performed the first calculation of the 2 à 2 scattering amplitudes for longitudinal spin-2 KK modes and shown that, contrary to claims in the literature, an intricate web of cancellations reduces the overall growth rate of the scattering amplitudes to being merely linear in s, as consistent with the behavior of 5D gravity. This holds both in theories based on a flat extra dimension and those, like Randall-Sundrum models, with a warped extra dimension. We have also demonstrated how to encode the conditions responsible for the cancellations as sum rules relating the couplings of the different KK states. This provides a more intuitive understanding of why some of the cancellations occur and highlights some key differences between theories with flat and warped extra dimensions. Our talk will summarize this work and indicate further directions for exploration.
Description:
Earth Day
User:
High-Energy Seminars
Time:
1:30pm - 2:30pm
Send Reminder:
Yes - 0 days 4 hour 0 minutes before start
Description:
Speaker: Nicholas Rodd
Title: Consistency of the Standard Model Effective Field Theory
Host: Da Liu
Zoom: https://zoom.us/j/186024391
Abstract:
In this talk I will describe how causality and the analytic structure of scattering amplitudes impose non-trivial constraints on the standard model effective field theory (SMEFT). For example, in the bosonic sector, I will explain how the bounds imply restrictions on the size of certain CP-odd operators by associated CP-even couplings. This result can be exploited to reveal a connection between constraints derived at colliders and limits on the neutron electric dipole moment. Further, I will demonstrate that in the fermionic sector, IR consistency requires that flavour violating dimension 8 operators are bounded by the flavour conserving variants. I will review how these bounds arise generally, and demonstrate how they are satisfied by a wide variety of UV completions.
April Fool's Day