Cosmology and Particle Physics • What we may Learn from Future Physics Experiments • Andris Skuja • University of Maryland
Status of Particle Physics and Cosmology • The parameters of particle physics have been used effectively to construct the present Standard Model of Cosmology • But the Cosmological model contains more than particle physics. It traces the evolution of the Universe from the Big Bang through Inflation to photon decoupling, and to the present. Recent measurements of the CMB by WMAP and other experiment have placed stringent limits on particle physics models, from neutrino masses to SUSY mSUGRA models. • On the other hand any laboratory measurements of particle physics parameters that are in disagreement with the Cosmological Model may generate problems of interpretation for the SCM.
Topics of Interest • Matter-Antimatter Asymmetry • Neutrinos (and more) • Dark Matter (Cold Dark Matter) • Supersymmetry & WIMP’s • Neutrinos • Axions • Inflation • Quintessence • Accelerating Universe • Sterile Quintessence • Magnetic Monopoles (none found) • Higher Dimension Universes • Mini–black holes from higher dimensions • Topological defects (cosmic strings, etc.)
Measuring the Afterglow of the Big Bang Wilkinson Microwave Anisotropy Probe (WMAP) Launched: Summer, 2001 (NASA/WMAP Science Team)
The Sonogram in Numbers:Angular Power SpectrumTop: Temperature fluctuations vs. angular scaleBottom: Cross-correlation of temperature and linear polarizationvs. angular scale
Dark Energy • WMAP measures a dark energy density ofΩΛ~0.7 (as required if ΩTOTAL~1.0). • Any calculation of the energy density of the Universe using Particle Theory obtains answers that disagree with observation and the Cosmological Model by 60 to 120 orders of magnitude. • This disagreement between the cosmological measurement and particle physics estimate is usually ignored. We have to conclude that we do not have a good model for the Dark Energy source.
Why do we see matter and cosmological constant almost equal in amount? “Why Now” problem Actually a triple coincidence problem including the radiation If there is a fundamental reason for rL~((TeV)2/MPl)4, coincidence natural Cosmic Coincidence Problem Arkani-Hamed, Hall, Kolda, Muramaya
Matter – AntiMatter Asymmetry • It is thought that the entire Universe consists predominately of matter only. Otherwise we would be able to observe high energy gammas caused by the annihilation of mater/antimatter • However, the standard model of particle physics does not contribute enough to the matter /antimatter asymmetry to account for the present observations. • Standard Cosmology leads one to believe that some extension of the Standard Model is necessary to account for our observations
CP violation in the Neutrino Sector • Maximal CP violation in the (massive) neutrino sector may be responsible for saturating the matter/antimatter asymmetry observation. • It is conjectured that not only do the 3 types of massive neutrinos oscillate from one flavor eigenstate to another (just as in B physics), but that the mass eigenvectors and the flavor eigenvectors are connected by a matrix that has maximally violating CP phase.
CP Violation in Neutrino Oscillations • Disappearance measurements cannot see CP violation effect • Very, very hard to see CP violation effects in exclusive (appearance) measurements. (From B. Kayser) • Only can see CP violation effects if an experiment is sensitive to oscillations involving at least three types of neutrinos. • All the terms (s12, s13, s23) must not be <<1 or effectively becomes only two component oscillation • For example, if s31 0 then s12 -s23 s12 + s31 + s23 0 To see CP violation must be sensitive to all three neutrino oscillations i.e. the hardest is usually the lowest (solar neutrino) Dm2 10-4 - 10-10 eV2
N3 N3 Matter-Antimatter Asymmetry (B 0)from Leptogenesis • Hard to generate a baryon asymmetry (B 0) using quark matrix CP violation • Generate L 0 in the early universe from CP (or CPT) violation in heavy neutrino N3 vs.decays (only needs to be at the 10-6 level) • B-L processes then convert neutrino excess to baryon excess. • Sign and magnitude ~correct to generate baryon asymmetry in the universe with mN > 109 GeV and mn < 0.2 eV n Mixing n Mixing
CP Violation at a Neutrino Factory (Ken Peach) e.g.Neutrino factory Golden Signature of “wrong sign” muons “right sign muons” “wrong sign muons” “right sign muons” “wrong sign muons” CP odd
Neutrino Factory (Proposed) • High intensity: 1021n/yr • Energy: 30-50 GeV for muons • Low backgrounds • Two experimental sites • 3000 Km • 1000 (7000) km
Neutrino Superbeams • What is a Superbeam? • Pretty much a “regular” neutrino beam but with a very intense proton beam. • Generally, proton power > ~1 MW puts you in “the club”. • However, “off-axis” or other types of beams may have some interesting advantages. • Everybody wants to be at one end or the other of one! • Almost every conceivable combination of proton accelerator laboratory and large underground laboratory/experiment seems to have been suggested. Particular studies have been made at CERN, KEK/JHF, Brookhaven and Fermilab. • The physics motivation which is currently driving most of these efforts is to search for a small admixture of nm- ne mixing with Dm2~ 0.003 eV2 where CP violation may also exist. • The picture could change significantly depending on the results from experiments like Kamland and Mini-Boone.
Leptogenesis may be insufficient • It may be that CP violation in the neutrino sector may also be insufficient to account for maximal matter/antimatter asymmetry. It may not be due to numerology –trivially the numbers may add up. Recent Theoretical papers suggest that the mechanism for generating the baryon asymmetry is difficult to evoke during the time available during early expansion, even if SUSY is included (e.g. see recent review of W. Bernreuther of Achen) • The seemingly obvious cosmological observation of a predominantly matter Universe has major consequences for particle physics. A GUT of particle physics is preferred at intermediate scales in Cosmological Models generating the baryon asymmetry.
WMAP and Dark Matter Most of the Universe is not made up of atoms: Ωtot~1, Ωb~0.04, Ωm~0.3 Most is Dark Matter and Dark Energy WMAP Most Dark Matter is Cold (non relativistic at freeze out) Significant Hot Dark matter is disfavored Neutrinos are not very cosmologically relevant: Ων<0.015 (WMAP) SUSY has excellent DM candidates: Neutralinos Also Axions may still be viable For 3 neutrinos: Ων< 0.015 -> mν< 0.23 eV ~ 5(Dm2atm)1/2
NGC 3198 Galaxy Rotation Curves Measure the velocity of stars and gas clouds from their Doppler shifts at various distances Velocity curve flattens out! Halo seems to cut off after r= 50 kpc v2=GM/r where M is mass within a radius r Since v flattens out, M must increase with increasing r!
Hot Gas and Galaxies Measure the mass of light emitting matter in galaxies in the cluster (stars) Measure mass of hot gas - it is 3-5 times greater than the mass in stars Calculate the mass the cluster needs to hold in the hot gas - it is 5 - 10 times more than the mass of the gas plus the mass of the stars!
Dark Matter Halo The rotating disks of the spiral galaxies that we see are not stable Dark matter halos provide enough gravitational force to hold the galaxies together The halos also maintain the rapid velocities of the outermost stars in the galaxies
Modified Dynamics • Mordehai Milgrom of the Weizmann Institute has propsed that standard Newtonian dynamics should be modified (MOND) for large scale low density systems. He has worked out a detailed scheme of how this occurs. He can account for all astronomical observations using a very detailed model of galaxies and his proposed dynamics. If true, in this case ΩCDM would be zero. • Stacey McGaugh of the University of Maryland has compared MOND predictions for low surface brightness galaxies with considerable success. He is a MOND believer. He is also very lonely !! • MOND appears to be inconsistent with the WMAP measurements (ΩM= 0.3 and ΩB= 0.04). McGaugh has calculated an anisotropy spectrum for the CMB based on MOND dynamics and claims it agrees with the BOOMERANG data.
Results WMAP Anisotropy Spectra • Position and height of firsttwo peaks pinned down • Polarization helps by determining extent of reionization Bennett et al. (2003)
CMB sorts out Mass density • Decrease in matter density leads to enhanced peaks • Position of first peak (in flat universe) is affected by matter density • CMB can break degeneracy • CMB appears to rule outΩM= 0.1 or smaller Modern Cosmology (2003) Dodelson
Dark Matter Candidates • Non Baryonic dark matter could take many forms: • Axions • Neutrinos (Hot Dark Matter) • Supersymmetric Particles (Cold Dark Matter) (Neutralinos) • Other WIMPS • Models of Large Scale structure formation indicate that Hot Dark Matter is excluded as the sole source of this phenomena. However, recent more detailed calculations indicate the Cold dark matter also does not yield the observed distribution of matter density in Large Scale structures (galaxies, etc.). A number of cosmologists argue that when both baryonic an CDM are included, such discrepancies will disappear. However, the work still must be done. • New measurements of neutrino masses and/or the discovery of the axion could be a complication.
Axions as Cold Dark Matter Extremely light particles, with masses in the range of 10-3 eV/c2 to 10-6 eV/c2 . The upper bound is set by neutrino fluxes from Supernova SN 1987 A, while the lower bound saturates the matter budget of the Universe (ΩA= 1.0) . Several axion searches are in progress – one exploring the lower bound while the other the upper bound. Interactions are 1012 weaker than ordinary weak interaction Density would be 108 per cubic centimeter Velocities are low Axions may be detected when they convert to low energy photons after passing through a strong magnetic field Y. Grossman et al. suggest that distant SuperNova appear dim because about 1/3 of their photons convert into axions on the way to earth.
The Strong CP Problem The QCD Lagrangian includes a gluon-gluon interaction term which violates CP (and T): parameter describing the QCD vacuum and depending also on quark mixing Such a term predicts an electric dipole moment for the neutron: With (A = 0.04 – 2.0) Present experimental limit |dn| < 0.63 x 10-25 e x cm || < 10-9 WHY SO SMALL? This implies
Proposed Solution of the Strong CP Problem Peccei-Quinn add a new, massless pseudoscalar field a(x) (The AXION) interacting with the gluon field. Add new term to Lagrangian: Peccei-Quinn scale Kinetic term La(CP conserving) is invariant for a a+ constant is “absorbed” in the definition of a Axion-gluon vertex a q q transitions a – p0 mixing mass ma > 0 (p0 decay constant fp = 93MeV)
Axion coupling axion-p0 mixing axions couple to photons (coupling strength with respect to p0 reduced by ~ fp/fa) model-dependent parameter of order 1 E/N=8/3 in GUT models Astrophysical arguments (energy loss of globular cluster stars) (Raffelt 1996):
LLNL Axion search • The light axion interacts with a strong (tuned) magnetic field to produce a free photon in the microwave range. The experiment detects the final state photons (or sets a limit on their production). Assuming the axion flux permeats the galaxy halo at the earths surface one can observe/exclude such models. • An axion with mass 1-2 m eV would close the energy density of the universe during inflation (ΩA= 1.0). An Axion of mass 1000 greater , on the other hand would only contribute ΩA= 0.01. A very light axion would contribute to the acoustic peak paramaterization of the CMB, and appears to be excluded by the WMAP measurements.
Slide provided by Prof. N. Sugiyama Very Light Axions appear to be excluded by WMAP
First Data at KSVZ sensitivity (C. Hagmann et al., Phys. Rev. Lett. 80 (1998) 2043)
Axion mass (meV) 2.00 2.25 2.50 2.75 3.00 3.25 3.50 10 DFSZ r(Gev/cm3) 1 KSVZ 0.1 500 550 600 650 700 750 800 850 Frequency (MHz) Local axion halo density excluded Abbreviations (previous Slide) : UF – University of Florida RBF – Rochester/BNL/FNAL This Slide – LLNL/MIT/Florida/LBNL/FNAL/INR(Moscow) KSVZ – Kim-Shifman-Vainshtein-Zakharov (and an axion coupling constant to photons of - 0.97) DFSZ – Dine-Fischler-Srednicki-Zhitnitskii (and an axion coupling constant to photons of 0.36)
g + Z a+ Z Solar Axion Production Solar axion differential flux on Earth (K. van Bibber et al., 1989) Photons/(cm2 s keV) for gagg = 10-10 GeV-1 (Flux proportional to gagg2 ) Axions may be produced in the sun by thermal photon-nucleus interactions in the Sun core (T~15.6 MOK)
CAST and Tokyo Helioscope Existing exclusion regions and CAST expected sensitivity Tokyo “helioscope”: L=2.3 m dipole, B=4T, aperture=2.0x9.2cm2 vertical movement ±28° w.r. to horizontal plane
CAST uses an LHC SC magnet as an Axion Telescope He4 flexible transfer line magnet Magnet Feed Box (MFB) being connected to the magnet
CAST: Looking at the Sunset Magnet power supply Cold Box Counting room
Neutrinos • (Some) Neutrinos have mass. A series of experiments (Homestake, SuperK, SNO, KAMLAND and many others) over the last 30 years have established that neutrinos have mass and oscillate. They are continuing to take data. Particle Theorists would like neutrinos to be Majorana particles (neutrinos and anti-neutrinos are the same particle). • Neutrinos are hot dark matter and relativistic. They “stream”.It is deemed that neutrinos alone could not form Large Scale Structure in the Universe. With the neutrino mass limited to a fraction of an eV. The WMAP results indicate that For 3 neutrinos: Ων< 0.015 -> mν< 0.23 eV Dodelson, et al. have pointed out that degeneracies exist in the CDM power spectrum for neutrinos.
Power Spectrum Degeneracy • Lowering the matter density suppresses the power spectrum • This is virtually degenerate with non-zero neutrino mass Dodelson
Running is degenerate with neutrino mass Very preliminary result: running does alleviate bound on neutrino mass. In the future, to understand the details of the Power Spectrum, even small neutrino masses become important. Abazajian, Dodelson, & Gates (2003)
3+1 Model: Atmospheric: nm nt Solar: LMA nem,t LSND: nmse Solar oscillations are to a 50%/50% mixture of nm and nt LSND nme oscillations are through high mass, mainly ns state with small admixture of nm and e 3+1 Neutrino Mass Model
If CPT is violated the Model accommodates solar, atmospheric, and LSND without sterile neutrinos Just allow the antineutrino Dm2 to be bigger than the neutrino Theoretical prejudice is consistent with mass being of the order of the splittings CPT Violation: Masses (Barenboim, Borissov, Lykken,Smirnov, Murayama, Yanagida;hep-ph 0201080)
Supernova Neutrinos • In a super nova explosion • Neutrinos escape before the photons • Neutrinos carry away ~99% of the energy • The rate of escape for neis different from nmand nt (Due extra neCC interactions with electrons) • Neutrino mass limit can be obtained by the spread in the propagation time • tobs-temit = t0 (1 + m2/2E2 ) • Spread in arrival timesif m0 due to DE • For SN1987a assuming emission time is over 4 secmn < ~30 eV
Solar Neutrino Deficit • Flux of solar neutrinos detected at the earth is much less than expected It is due to neutrino oscillations? • The “Standard Solar Model” is OK • Wide range of measurement techniques • Confirmed by man generated neutrino fluxes • All large experiments use Cherenkov detector techniques Super- K (Japan) imageof the sun using neutrinos
Advantages of Heavy vs Light Water ne + dp + p + e- (D2O) ne + e-ne + e- (H2O or D2O) Cross section (Ecm)2 = s s = 2 mtarget En sN/se- = Mp/Me 2000 But x5 more electrons in H2O than n’s SNO (1kton) 8.1 CC events/day SuperK (22ktons) 25 events/day Sudbury Neutrino Observatory (SNO) 1000 tons D2O(12m Inner Vessel)