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X-WR-CALNAME:LBNL Physics Division Research Progress Meetings
X-ORIGINAL-URL:https://rpm.physics.lbl.gov
X-WR-CALDESC:Events for LBNL Physics Division Research Progress Meetings
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DTSTART:20220101T000000
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BEGIN:VEVENT
DTSTART;TZID=UTC:20220811T160000
DTEND;TZID=UTC:20220811T170000
DTSTAMP:20260422T062641
CREATED:20220809T212557Z
LAST-MODIFIED:20220809T212557Z
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SUMMARY:David Dunsky (LBNL) "Dark Radiation Constraints on Heavy QCD Axion Theories"
DESCRIPTION:Abstract: The explicit breaking of the PQ symmetry by higher dimensional operators can spoil the dynamical relaxation of the strong CP angle to its minimum of zero. One solution to this PQ “quality problem” is to introduce heavy QCD axions. Such axions acquire a mass from physics occurring far above the QCD scale and possess a potential more robust to corrections from higher dimensional PQ breaking operators. However\, in much of the (m_a\, f_a) plane\, heavy QCD axions can generate large amounts of dark radiation when decaying. In this talk\, I will discuss the cosmological evolution of heavy QCD axions in the early Universe\, their interactions with the Standard Model thermal bath\, and precise dark radiation constraints arising from their decays. In addition\, I will discuss how including a mirror photon – common in heavy axion theories involving mirror QCD sectors – modifies this picture and can lead to dangerous amounts of dark radiation
URL:https://rpm.physics.lbl.gov/event/david-dunsky-lbnl-dark-radiation-constraints-on-heavy-qcd-axion-theories/
LOCATION:HYBRID 50A-5132 (Sessler Conference Room)\, https://lbnl.zoom.us/j/91782268585\, 50A-5132
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BEGIN:VEVENT
DTSTART;TZID=UTC:20220830T160000
DTEND;TZID=UTC:20220830T170000
DTSTAMP:20260422T062641
CREATED:20220830T202403Z
LAST-MODIFIED:20220830T202403Z
UID:1929-1661875200-1661878800@rpm.physics.lbl.gov
SUMMARY:Bibhushan Shakya (DESY) - "Gravitational Wave Probes of the Dark Universe"
DESCRIPTION:ABSTRACT: (This is a Hybrid/ZOOM Meeting)\n \n\n\n\nGravitational waves offer a powerful probe of early Universe phenomena. A particularly well-motivated BSM target for gravitational wave experiments is a first order phase transition in a dark sector\, where bubbles of true vacuum nucleate and expand in a background of false vacuum. We will discuss several new ideas related to gravitational wave signals from such dark phase transitions\, including novel forms of gravitational wave signals beyond the traditionally studied ones sourced by bubble collisions and sound waves\, as well as prospects of detecting phase transitions that could have been responsible for the production of dark matter through various nonthermal mechanisms. \n\nJoin Zoom Meeting: \nhttps://lbnl.zoom.us/j/94367647939?pwd=EJQRjhlaGc4dFFqT1c1WEtRSnVRZz09 \nMeeting ID: 943 6764 7939\nPasscode: 531399\n\n\nTime:         4:00 PM\n\nConference Room Location: 50-5132\n\n      Bibhushan Shakya (DESY) Webpage: https://sites.google.com/view/bibhushan-shakya
URL:https://rpm.physics.lbl.gov/event/bibhushan-shakya-desy-gravitational-wave-probes-of-the-dark-universe/
LOCATION:HYBRID 50A-5132 (Sessler Conference Room)\, https://lbnl.zoom.us/j/91782268585\, 50A-5132
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