The ALPS Experiment DDaarrkk MMaatttteerr aanndd PPaarrttiiccllee Physics at Lowest Energies A. Lindner, DESY DESY Summer Student Lecture, 30 July 2010 Today’s Agenda > The ALPS Lecture which is the last one of the common lectures in the past two weeks. Therefore it might be a good opportunity to ask questions and rise some items. > Question Time!  Nagging issues related to the common lectures.  Curiosity concerning DESY in general.  Everything you wanted to know about DESY physics but were afraid to ask (answers not guaranteed).  Other items? > “Hands on” with Cosmic Rays and a tour to the ALPS? Axel Lindner | Summer Students 2010 | ALPS | Page 2 The ALPS Lecture > An Introduction to the Axion > Dark Stuff in the Universe > From Axions to ALPs and WISPs > How to search for WISPs > The ALPS Experiment at DESY > Outlook on possible future Activities > Summary Axel Lindner | Summer Students 2010 | ALPS | Page 3 Table of Contents > An Introduction to the Axion > Dark Stuff in the Universe > From Axions to ALPs and WISPs > How to search for WISPs > The ALPS Experiment at DESY > Outlook on possible future Activities > Summary Axel Lindner | Summer Students 2010 | ALPS | Page 4 The Standard Model of Constituents and Forces / Constituents: s e b u > Quarks c / k u . c > Leptons a . p p d i r g . w Forces: w w / > electromagnetic :/ p t t h > strong > weak > gravitation Only the Higgs boson is missing! LHC is on the way to probe its existence. Axel Lindner | Summer Students 2010 | ALPS | Page 5 The Standard Model of Constituents and Forces / Constituents: With these few s e b constituents and forces all u > Quarks c / k phenomena observed on u . c > Leptons a earth can be . p p d described (in principle). i r g . w Forces: w w Since more than 30 years / > electromagnetic :/ p t there is not a single t h > strong particle physics experiment > weak really questioning the > gravitation Standard Model. Only the Higgs boson is missing! LHC is on the way to probe its existence. Axel Lindner | Summer Students 2010 | ALPS | Page 6 A Flaw in the Standard Model? The neutron has a strange property: It consists of three charged quarks, but does not show any static electric dipole moment. http://www.lbl.gov/Science-Articles/Archive/sabl/2006/Oct/3.html http://en.wikipedia.org Why do the wave functions of the three quarks exactly cancel out any observable static charge distribution in the neutron? Axel Lindner | Summer Students 2010 | ALPS | Page 7 A Flaw in the Standard Model? Naively one expects for the neutron electric dipole moment: ml ht 3. ct/ O 6/ 0 0 2 bl/ a s d  10-15 e·cm. m e/ v n-QCD c hi c 5 Ar -1 s/ 0 e 1 cl rti  A - e c n e ci S v/ o g bl. w.l w w p:// htt The data show: d < 10-26 e·cm! n-data How to explain the difference of at least 11 orders of magnitude? Axel Lindner | Summer Students 2010 | ALPS | Page 8 Eleven Orders of Magnitude … expecting a planet and finding the nanoscale … Axel Lindner | Summer Students 2010 | ALPS | Page 9 Two Possibilities > The vanishing electric dipole moment of the neutron is just accidental. The parameters of QCD are “fine-tuned”, nothing remains to be explained. A physicist’s nightmare: > Can one think of any explanation? If yes, how to confirm this? Axel Lindner | Summer Students 2010 | ALPS | Page 10