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SUMMARY:An even lighter QCD axion - Pablo Quilez (DESY)
DTSTART:20210128T160000Z
DTEND:20210128T170000Z
UID:TALK156691@talks.cam.ac.uk
CONTACT:Joseph Davighi
DESCRIPTION:*The seminar will take place via zoom:\nhttps://maths-cam-ac-u
 k.zoom.us/j/95215212460?pwd=TWN5cjJ3azErSUYremw5UWRKL0NKUT09*\n\n\nAbstrac
 t: We explore whether the axion which solves the strong CP problem can nat
 urally be much lighter than the canonical QCD axion. The  Z_N symmetry pro
 posed by Hook\, with N mirror and degenerate worlds coexisting in Nature a
 nd linked by the axion field\, is considered. Two specific ultraviolet Z_N
  completions are developed: a composite axion one and a KSVZ-like model wi
 th improved Peccei-Quinn quality.\n   On a second step\, we show that dark
  matter can be accounted for by this extremely light axion.  This includes
  the first proposal of a ``fuzzy dark matter'' QCD axion. A novel misalign
 ment mechanism occurs -- trapped misalignment-- due to the peculiar temper
 ature dependence of the Z_N axion potential. The dark matter  relic densit
 y is enhanced because the axion field undergoes two stages of oscillations
 : it is first trapped in the wrong minimum\, which effectively delays the 
 onset of true oscillations. Furthermore\,  the trapped misalignment  can a
 lso  dynamically  source the recently proposed kinetic misalignment mechan
 ism.\n   The resulting universal enhancement of all axion interactions rel
 ative to those of the canonical QCD axion has a strong impact on the prosp
 ects of ALP experiments such as  ALPS II\, IAXO and many others. For insta
 nce\, even Phase I of Casper Electric could discover this axion. 
LOCATION:Virtual Seminar 
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