PASI2006: Beyond the Standard Model in Cosmology, Astroparticle and Particle Physics

PASI2006:Beyond the Standard Model inCosmology, Astroparticle and

Particle Physics

Marleigh SheaffUniversity of Wisconsin

DPyC/SMF June 14-16, 2006

Marleigh Sheaff, Wisconsin 2DPyC/SMF June 2006

This Pan-American Advanced Studies Institute will be held in conjunction with the Sixth Latin American Symposium on High Energy Physics (VI-Silafae) and the Twelfth Mexican School of Particles and Fields (XII-MSPF), October 23 - November 8, 2006.


PASI2006 ORGANIZING COMMITTEE

• Marleigh Sheaff (University of Wisconsin, USA), chair• Marcela Carena (Fermilab, USA)• Daniel Chung (University of Wisconsin, USA)• Joao dos Anjos (CBPF, Brazil)• Miguel-Angel Perez (CINVESTAV, Mexico)


MOTIVATION • Present the evidence for physics beyond the Standard Model

(SM).• Demonstrate that these three fields are not disjoint, but that

results in each inform the others. • Showcase the very fine work going on in these fields in the

Americas.• Bring together young physicists (Post Docs and Advanced

Graduate Students) working in the three fields throughout the hemisphere.

• Foster future collaborations that are both multidisciplinary and multinational.


PLANS• Start with eight Days of Lectures given by

physicists who are not only experts in each area but also have excellent presentation skills

• Discussion sessions following each day's lectures where students can ask questions. A number of Mexican physicists with expertise in these fields have agreed to help us with these sessions.

• Joint program for PASI2006, VI-Silafae, and XII-MSPF for the next eight days. Mostly research seminars given in plenary sessions.


LECTURERS

• Marcela Carena (Fermilab, USA) - Electroweak Symmetry Breaking, SM and Beyond, Higgs Physics at the LHC/ILC

• Daniel Chung (U. of Wisconsin, USA) - Particle Cosmology Fundamentals• Daniel de Florian (Buenos Aires U., Argentina) - QCD, a Background to New

Physics• Andre de Gouvea (Northwestern U., USA) - Neutrino Physics,

Phenomenology• Scott Dodelson (Fermilab and U. of Chicago, USA) Cosmology• Joao dos Anjos (CBPF, Brazil) - Neutrino Physics, Experiment• Boris Kayser (Fermilab, USA) - Neutrino Physics, Theory• Alex Kusenko (UCLA, USA) - cosmology/astroparticle physics• Mattias Neubert (Cornell U., USA) - B/K Physics• Abdel Perez-Lorenzana (CINVESTAV, Mexico) - Extra Dimensions at

LHC/ILC• Carlos Wagner (Argonne Lab and U. of Chicago, USA) - SUSY, including

LHC/ILC Physics


DISCUSSION LEADERS

• Guilermo Contreras (CINVESTAV, U. Merida)• Jens Erler (IF-UNAM)• Ricardo Lopez (CINVESTAV, Mexico)• Omar Miranda (CINVESTAV, Mexico)• Eduardo Ponton (Columbia U., USA)• Sarira Sahu (ICN-UNAM)• Alberto Sanchez (CINVESTAV, Mexico)


What is the SM?

• Gauge theory.• Describes strong, electromagnetic, and weak

interactions.• SU(3) x SU(2) x U(1)• Explains the results of all experiments to date.

(Well, almost!)• Basic theory is massless.


What does the SM tell us?

• Basic Building Blocks found in ordinary matter or in all particles produced in experiments to date are the 3 families of quarks and leptons and their antiparticles.

• To each quark and lepton there corresponds an antiquark or antilepton for which all additive quantum numbers are of the opposite sign. These are not found in ordinary matter but can be produced in experiments.

• Forces between the quarks and leptons can be understood as the exchange of force carriers (gauge bosons) for three of the four known forces (Weak, EM, and Strong).


What does the SM NOT tell us?

• What about the fourth known force, gravity? Can we incorporate it into the theory? Can we realize Einstein's dream of a Grand Unified Theory?

• The gravitational force is much weaker than the other three. Energy scale is very high.

• MPL (ch/GN)1/2 ~1019 GeV.


Electroweak Unification

• Two of the four known forces are seen to be unified.

• Scale is ~(300 GeV)2.• The masses of the gauge

bosons are very different. The carriers of the weak force (W,Z) have masses ~100 GeV. The carrier of the em force, the photon, is massless.

• Range of weak force is very short <10-17 cm.

Data from the HERA ep Collider



• Why are the masses of the gauge bosons so different?• Why are the masses of the various quarks and leptons so

different, spanning many orders of magnitude?• Why are there three families of quarks and leptons?

Ordinary matter is made up only of u and d quarks and electrons.


HIGGS Field

• Breaks electroweak symmetry by spontaneous symmetry breaking giving masses to the W and Z.

• Also gives masses to the quarks and leptons (slows them down so they do not travel at c).

• Must permeate all space in order to do this. • Its couplings are proportional to mass.• Simplest interpretation, the SM Higgs, is a single

scalar boson, but this is only one of the many possibilities proposed.


Properties of SM Higgs

• W Boson Scattering grows with energy A ~ GFE2 and violates unitarity at 1.8 TeV

• Unitarity can be restored by adding a single spin 0 particle (scalar boson) with couplings that are precisely those of the SM Higgs


Expected Mass of the Higgs

• mH = 126 +73/-48 GeV

• mH 260 GeV (95% c.l.)

LEPEWWG fit at the Zo pole from electroweak precision data and SM theory


SM Higgs at the LHC

• Finding the Higgs is the primary goal of the two main experiments being built for the the Large Hadron Collider at CERN, CMS and ATLAS.

• The LHC is expected to come on line and to be commissioned sometime in Fall 2007.


From Joe Lykken at Pheno 06 -


Compact Muon Solenoid


SM Higgs in CMS


SM Higgsin ATLAS


Is discovery really the Higgs?

• Is its coupling proportional to mass?• How about its spin and parity - is it JP = 0+?

• Does it condense in the universe?• To answer these detailed questions it is felt

that we will need both the LHC and the ILC, the International Linear Collider.


The International Linear Collider

• e+ e- Collider with 500 GeV center-of-mass energy.• To be upgraded to 1 TeV later on.• Must be linear collider at this energy to avoid huge

losses to synchrotron radiation.• Beams accelerated along path 15 km.• Beams focused down to a few nanometers in the

collision region to get the luminosity required for the measurements. ~ 1034 cm-2 sec-1.

• Need for high precision places stringent requirements on the detectors.


The International Linear Collider


Measure properties of the Higgs• Study SM Higgs (assuming

discovery at the LHC).• Precise measurement of

branching fractions proves that Higgs is responsible for masses of SM particles, i.e., couplings mass.

• Bands show SM theoretical errors. Error bars show expected experimental errors for 500fb-1 at 350 GeV.


The Hierarchy Problem

• Mass of Higgs at the scale where electroweak symmetry is broken must be of order MW to restore unitarity through cancellation of diagrams.

• This is many orders of magnitude below the mass of the GUT scale where the strong interaction becomes unified with the electroweak, MGUT ~ 1015-1016. Squared mass of Higgs shows a quadratic divergence as we run it up to this scale.

• The scale of the gravitational interaction is even higher, MPL ~ 1019.


Supersymmetry (SUSY)• Each SM fermion has a superpartner that is a boson

and each SM boson has a superpartner that is a fermion. (Boson-Fermion Symmetry)

• Superpartners have the same quantum numbers and couplings as their partner SM particles.

• Contributions to loop diagrams for radiative corrections to the Higgs mass are of opposite sign and cancel removing the quadratic divergence as we run the mass up to GUT scale.

• Naturalness requires that |m2B - m2

f| ≤ O(1 TeV2).• With SUSY, couplings for SM forces meet at

common energy scale ~1015-1016 within current experimental bounds.


History Repeats Itself

• Electron is pointlike, at least down to ~10-17 cm.• Since like charges repel, how can electron's charge

be confined to such a small volume?• Energy required to do this is ∆mec2 ≈ e2/re and

e2/re ≈ GeV(10-17cm/re).

• ∆mec2 > mec2 for re smaller than 10-13.

• Electromagnetism doesn't work below re of 10-13.


Solution - double the number of particles by adding antiparticles

• Vacuum polarization - electron continuously emits and reabsorbs virtual photons, which produce e+ e- pairs, thus shielding electric charge.

• ∆me ≈ me(/4)log(mere).

• Only 10% of me even at Planck scale rPL ~ 10-33.


Higgs is Pointlike

• Higgs self-coupling causes similar problem.

• Energy required to contain it in its pointlike size is ∆mH

2c4 ~ (hc/rH)2.• Weak force breaks down

at order 1 TeV.


Add superpartners which doubles number of particles

• Vacuum bubbles of superpartners cancel energy due to Higgs self-coupling.

• ∆mH2~(/4)m2

SUSYlog(mHrH).• Takes us to GUT scale, i.e.,

shorter distances.


SUSY must be a broken symmetry

• If SUSY were an exact symmetry, superpartners would have exactly the same mass as their SM counterpart.

• No superpartner has yet been discovered, although searches have been carried out up to the highest masses achievable in present experiments.

• We expect that, if SUSY particles do exist, the lowest mass states are likely to be discovered at the LHC.


R-Parity

• R-parity was introduced to forbid couplings that violate baryon number or lepton number conservation, which allow a proton decay rate well above that allowed by experiment.

• R = (-1)2j+3B+L, where j=spin, B=baryon number, and L=lepton number. R=+1 for SM particles and -1 for superparticles.

• Superparticles must be produced in pairs.• The lowest mass superpartner will be stable since it

can't decay to SM particles,.


The Cosmology Connection• Universe started with the (hot) Big Bang some 15 billion

years ago.• BB was followed by a period of rapid expansion called

inflation. • Expansion has continued since then at a slower rate with a

continual decrease in temperature and stretching of the scale.

• Hubble constant, H=72 km sec-1 Mpc-1. Velocity at which distant objects recede from us is proportional to their distance. We can measure by their red shift.

• Accelerator energies are now getting high enough to reach the energy present in the very early universe. Energy related to temperature through Boltzmann's constant, kB.


History of the Universe

• LHC Energy is above the energy of the universe at the time when EW symmetry was broken.

• Takes us closer to the Big Bang than 10-11 sec!

• Allows us to explore the scale where we expect to see SUSY particles.


SUSY at the LHC and ILCGaugino Mass Unification

• LHC is expected to discover SUSY particles that couple through the strong interaction squarks and gluinos and their decay products.

• ILC is expected to measure all the SUSY particle masses and couplings precisely.

• 1 TeV energy, 1000 fb-1, and high beam polarization needed to fully characterize SUSY and to discover the forces that break SUSY.



• What everything else is.• Cosmological observations indicate that SM

particles comprise only ~ 5% of the energy budget of the universe.

• Since cosmological observations and particle physics must agree, new physics (i.e., physics beyond the SM) is needed to explain this.


Energy Budget of the Universe

• Stars and Galaxies ~ 0.5%• Neutrinos ~ 0.1-1.5%• Rest of Ordinary Matter (protons,

neutrons,electrons) 4.4%• Antimatter 0%• Dark Matter 23%• Dark Energy 73%


Evidence for Dark Matter

• Expect vc ~ r -1/2 outside luminous region

• Find vc a constant• Inconsistency resolved by

postulating Dark Matter.• Confirmed by

measurements of gravitational lensing

Rotational Curves of Galaxies and Galactic Clusters

NGC 2403


Distribution of Dark Matter


Could the LSP explain Dark Matter?

• Dark Matter feels gravitational interaction since it clumps in the vicinity of luminous (SM) matter.

• The properties of the least massive superpartner (LSP) make it a likely candidate to be Dark Matter. Typically it's a mixture of electoweak gauginos and Higgsinos called the neutralino, .

• LSP mass expected to be ~100 Gev - 1 TeV.• Would interact only weakly (WIMP).• LSP would have relic abundance of the correct size to

match the Dark Matter abundance.


The Neutralino as Dark Matter Jonathan Feng - Frontiers in Contemporary Physics 2005Jonathan Feng - Frontiers in Contemporary Physics 2005


Evidence for Dark Energy• Supernovae Ia are Standard

Candles - luminosity scales with the inverse of the distance squared.

• Recession velocity measured by red shift depends on distance of SN from us.

• SN with largest red shift have lower luminosity than expected indicating that the expansion of the universe is accelerating.

SDSS II


Evidence for Dark Energy

• Dark Energy is equivalent to Einstein's cosmological constant, .

• Fits to WMAP data show it is needed to describe temperature fluctuations observed in CMB.

• Temperature fluctuations are the result of perturbations that occurred during Inflation.


What does the SM NOT tell us?• Why there is a complete asymmetry between

matter and antimatter in the universe. Where did all the antimatter go?

• The relatively small CP violation seen in the quark sector does not appear to be large enough to produce this.

• The discovery of large mixing angles in the lepton sector indicate we are seeing new physics. More experiments are needed to elucidate it.


Other Evidence for Physics Beyond the SM - The Neutrino Revolution

• Over the past 8 years, neutrino experiments have become precise (and clever) enough to discover that neutrinos oscillate.

• This means that neutrinos have mass.• SM neutrinos are only left-handed. This can't be

if they have mass. OK if neutrinos are their own antiparticles.

• SM neutrinos conserve lepton number, but not if they are their own antiparticles.


Properties of Neutrinos

• Neutrinos have mass and therefore no longer travel at c.• If we boost ourselves to near c and look back, the neutrino

will appear to be right-handed.• Anti-neutrinos are right-handed, so if neutrinos are their

own anti-particles this can be accommodated in the SM.

e


Solar Neutrino Problem finally resolved after 40 years

• Ray Davis was a chemist at Brookhaven National Laboratory.

• He placed a very large tank of cleaning fluid deep in the Homestake mine to detect electron neutrinos from the Sun using the reaction e+Cl37e-+Ar37.

• The number of e's detected with energy above threshold for this reaction, 814 keV, was only ~1/3 of the flux expected in the Standard Solar Model of Bahcall.

• Ray Davis received the 2002 Nobel Prize for this landmark measurement.


Neutrino Oscillations?

When only two species of neutrino contribute -

For , P( ) = sin2 2 sin2 (m2 ) .

For no flavor change P( ) = 1 - sin2 2 sin2 (m2 ) .

(-) (-)

(-)(-)

L4E

L4E

Appearance

Disappearance

m2 = (m2 - m

2)2. Gives difference but not the sign.


Missing Neutrinos Found by SNO!

FLUX of e

FLU

X o

f +

Data from D2O with NaCL added

e+Dp+p+e- (CC - e only) x+Dp+n+x (NC - all 3)

• CC/NC=0.306±0.026±0.024• Full flux of 8B e predicted in

SSM seen, 5x106 cm-2s-1.• Consistent with MSW effect

(matter effects in the Sun) and neutrino oscillations.

• Adding KamLAND data makes oscillation parameters more precise.


Mikheyev-Smirnov-Wolfenstein Effect

• Neutrinos produced in the sun are all e. SNO 8B detection threshold is 5MeV.

e survival probability is just e

fraction of 2 (LMA solution).• Neutrinos do not oscillate as

they travel from the Sun to the Earth, since they have gone through an adiabatic matter resonance and leave the Sun in the mass eigenstate 2.


KamLAND Reactor Experiment

• Measure disappearance of e produced by many nuclear reactors.

• Observe first oscillation minimum at ~180 km assuming Large Mixing Angle solution and CPT.

• (Nobs-NBG)/Nno-osc =

0.611±0.085±0.041

Nob

s/Nno

-osc


Solar plus KamLAND

m122 = 7.9 (+0.06 -0.05) x 10-5 eV2

• tan212 = 0.40 (+0.10 -0.07)


Atmospheric Neutrino Measurements

• Downward going do not oscillate.

• Upward going , which travel longer distances, do.

m232 ~ 2.4 x 10-3 eV2

23 = 45o ± 10o

• Results confirmed by two long baseline accelerator experiments, K2K and MINOS.SuperK


So far only a Limit on 13

• Determined from 3 fit to solar, KamLAND, and CHOOZ data.

ms2 = 8.0 x10-5 (2)

• tan2s = 0.45 (2)

• sin2x ≤ 0.13 (90% cl)

Balantekin,Barger,Marfatia,Pakvasa,Yuksel

hep-ph/0405019, updated March 2005

+0.7-0.6

+0.17-0.12


MNSP Matrix (like CKM for quarks)

• Both solar and atmospheric mixing can be approximated by two-flavor mixing because m23

2 >> m122 and 13 is

very small.• We have only an upper limit on 13. We need to measure

it more precisely to see if it is enough above zero to allow measurement of CP violation in the lepton sector, since it multiplies the CP violating phase term ei.

Solar Atmos.


What have we learned about 's so far?Boris Kayser - Frontiers in Contemporary Physics - 2005


Hierarchy of Masses and Mass Scale Yet to be Determined

• We don't know whether m3 is larger or smaller than the other two.

• We don't know the absolute scale.

• Normal hierarchy is preferred to be more like that seen in the quarks and charged leptons.

NormalNormal InvertedInverted


Cosmological Limit on Neutrino Masses

• Large scale structure of the universe imposes constraint on the sum of neutrino masses.• Large scale structure means ≥ 10 kpc. m < 0.43 eV and mass of the lightest < 0.13 for 3 heavy neutrino ( astro-ph/04073772).


What about LSND?• Significant excess of e seen

in a short baseline beam (3.8).

m2 ~ 1eV2 incompatible with measured solar and atmospheric in a three neutrino picture.

• Could there be sterile 's?• Not confirmed by any other

experiment. Results of MiniBooNE (expected this summer) will confirm or refute.


Are 's are Majorana, i.e., = ? Need to measure 0 more precisely to test.

ll = 2 in this decay. Violates lepton number. = 2 in this decay. Violates lepton number.


If 's are Majorana - • Most popular theory to explain why masses are so small

is the so-called See-Saw mechanism.• Heavy neutrinos would have been produced during the hot

Big Bang and would have decayed.• If they were to couple differently to e+ than e-, they would

violate CP (leptogenesis).• SM sphaleron processes would then convert some of the

lepton asymmetry into baryon asymmetry.• It is extremely important to measure CP violation for the

light 's. We may never be able to produce the heavy neutrinos to see if they violate CP, but a positive result for the light 's would lend credibility to the theory.


Summary and Conclusions

• There is convincing evidence for New Physics, i.e., Physics beyond the Standard Model.

• New data are needed to discriminate between the many models proposed.

• New data are just over the horizon.• This is a very exciting time to be working in

Cosmology, Astroparticle or Particle Physics.• Please come to PASI2006/VI-Silafae/XII-MSPF and

participate in the lectures, seminars and discussions!

Documents

PASI2006: Beyond the Standard Model in Cosmology, Astroparticle and Particle Physics