The Standard Model and Beyond

TheNeMajoutrinosr ProbImlemsplicinatiPons/questionsarticle Physics Theand HoStwandaWerdHopMoe todelAddrandessBeyThemond

Key constituent of the Universe •

WhyThe astandare therdmasmodelses so small? • • – Planck/GUT scale? e.g., seesaw Toesr tgeneraliing the standazation,rdmmodel m2 /M • ν ∼ D N Problems •Are the neutrinos Dirac or • Majorana? Beyond the standard model • – Neutrinoless double beta decay Where are we going? • (ββ0ν) (inverted or degenerate spectra)

NYS APS (October 15, 2004) Paul Langacker (Penn)

Yoichiro Nambu Symposium (April 21, 2005) Paul Langacker (Penn)

Yoichiro Nambu Symposium (April 21, 2005) Paul Langacker (Penn) Neutrinos Implications/questions

The New Standard Model

Key constituent of the Universe • Standard model, supplemented with neutrino mass (Dirac or • Majorana): Why are the masses so small? • SU(3) SU(2) U(1) classical relativity – Planck/GUT scale?× e.g.×, seesa× w or generalization, m m2 /M ν ∼ D N

AreMathematithe callneutry iconsinos stentDiracﬁeld otheor ry of strong, weak, • • Majoelectromagneticrana? interactions

– Neutrinoless double beta decay 16 Correct to ﬁrst approximation down to 10− cm •(ββ0ν) (inverted or degenerate spComectrplica)ated, free parameters, ﬁne tunings must be new physics • ⇒

NYS APS (October 15, 2004) Paul Langacker (Penn) Yoichiro Nambu Symposium (April 21, 2005) Paul Langacker (Penn) Neutrinos Implications/questions The Fundamental Forces

Strong Electromagnetic Weak Gravity Keyp constituentn of the Universe 6 6 • 0 π e− ν¯e e− p p 6 6 6 6 © 6 6 pion γ W − g Whyp 6 are the6n masses so small? • ¨ ¨ ¨ § ¤ § ¤ § ¤ ¨ ¨ ¨ d u ¦ ¥ ¦ ¥ ¦ ¥ graviton 6 6 © © © 6 IVB © © © – Planck/GUTG scale?6photone.g.,6 seesaw 6 6 n (spin 2) § ¤ § ¤ § ¤ e− p2 or ¦gluongenerali¥ ¦ ¥ ¦ ¥ zation, mν mD/MN d 6 6u ∼ Are the neutrinos Dirac or mπr 2 M r m1m2 • 2 e− e 2 e− W GN VMajo= gπranra? r g r r

g2 e2 1 g2E2 11 38 strengt– Neh:utrinolπ 14ess αdoubl= e beta decay 10− GN m1m2 10− 4π 4π ∼ 137 M2 ∼ ∼ ∼ W (m1=m2=1 GeV) (ββ0ν) (inverted or degenerate(E = 1 MeV) spectra) h¯ h¯ 16 range: 10− cm mπc ∞ MW c ∞ 13 ∼ ∼ 10− cm 1 fm ≡

YInoictrohiductoryro Namslidesbu Symposium (April 21, 2005) PaulPLangacaul Langacker (Pkerenn)(Penn) Neutrinos Implications/questions

Uniﬁcation of Forces Key constituent of the Universe • Strong Electromagnetic Weak Gravity hadrons: p, n; charged particles: p, n, π; e, µ, τ ;, all particles (always Why are the 0masses so small? • pions: π±, π ; e−, µ−, τ −; neutrinos: attractive) ν , ν , ν (QCD– Pl:anck/GUTquarks, spcale?; π± e.g., seesawe µ τ gluons) 2 or generalization, mν mD/MN E +∼B ← → Are the neutr(Maxwinosell) Dirac or Electroweak (SU(2) U(1)) • QCD ← × → ←Majorana? → Grand Uniﬁcation (GUT)? ← → – Neutrinoless doublTheeory bofetaEverythingdecay(superstring)? ← → (ββ0ν) (inverted or degenerate spectra)

Yoichiro Nambu Symposium (April 21, 2005) Paul Langacker (Penn)

Introductory slides Paul Langacker (Penn) Neutrinos Implications/questions Gauge Theories

Gauge symmetry requires existence of (apparently) massless spin-1 • Key(vectoconsrtituent, gauge)ofbosonsthe Universe • Interactions prescribed up to group, representations, gauge Why• are the masses so small? • coupling – PlAnalogousanck/GUTto sQEDcale?(Ue.g.(1)),, sbuteesagaugew self interactions for non- • 2 oabr generalielian groupszation, mν m /MN ∼ D Standard model: SU(3) SU(2) U(1) Ar•e the neutrinos ×Dirac ×or • MajoAppranlica?ation to strong (short range) conﬁnement • ⇒ – NeApputrinollicationess todoublweake (shobetart drange)ecay spontaneous symmetry • ⇒ (βbreakβ0νing) ((invertHiggsedor dynamior degencal) erate spectra) Unique renormalizable ﬁeld theory for spin-1 •

Introductory slides Paul Langacker (Penn)

Yoichiro Nambu Symposium (April 21, 2005) Paul Langacker (Penn) Neutrinos Implications/questions The Standard Model

Gauge group SU(3) SU(2) U(1); gauge couplings g , g, g! • × × s Key constituent of the Universe • u u u νe d d d e− Why are the mas! ses"soL small! ?"L ! "L ! "L • – Planck/GUT scale?uR e.g.,usReesawuR νeR(?) dR d2 R dR e− or generalization, mν mD/MN R ( L = left-handed, R∼= right-handed) Are the neutrinos Dirac or • SU(3): u u u, d d d (gluons) Majo• rana? ↔ ↔ ↔ ↔ 0 SU(2): u d , ν e− (W ±); phases (W ) –•NeutrinolessL ↔doublL e eLbeta↔ dLecay (ββ ) (inverted or degenerate U(1)0ν : phases (B) •spectra)

Heavy families (c, s, ν , µ−), (t, b, ν , τ −) • µ τ

YoichiInrotroNamductorybu Sympslidesosium (April 21, 2005) PPaulaul LangacLangackkerer(P(Peenn)nn) 10 16. Structure functions Table 16.1: Lepton-nucleon and related hard-scattering processes and their primary sensitivity to the parton distributions that are probed.

Main PDFs Process Subprocess Probed

! N ! Xγqqg(x0.01),q,q ± → ± ∗→ !+(! )N ν(ν)XWqq − → ∗→# ν(ν)N!(!+)XWqq →− ∗→# νN µ+µ XWscµ+ s → − ∗→→ pp γX qg γq g(x 0.4) → → ∼ pN µ+µ Xqqγ q → − →∗ pp, pn µ+µ Xuu, dd γ u d → − → ∗ − ud, du γ → ∗ ep, en eπX γ q q → ∗ → pp W ! XudW u,d,u/d → → ± → pp jet +X gg,qg,qq 2jq,g(0.01 x 0.5) → → Neutrinos Implications/questions Quantumall polarizedChromoPDFs. Tdynamihese polarizedcs (QPDFsCDma)y be fully accessed via ﬂavor tagging in Quantumsemi-inclusiChromove deep idynaminelastic scatcs t(Qering.CDF)ig. 16.5 shows several global analyses at a scale of 2.5 GeV2 along with the data from semi-inclusive DIS. Modern theory of the strong interactions Key constituentModernoftheotheryUniverseof the strong interactions • Quark model/ color/ 0.7 •

conﬁnementWhy are the masses so smallx f(x) ? • 0.6 – Planck/GUT scale? e.g., seesaw Low energy symmetries 0.5 • 2 (+orrealigeneralization,zation,breakimng)ν mD/MN ∼ 0.4 (SU(3) SU(3) ) L× R Are the neutrinos Dir0.3ac or • HadMajoroniranca?models: Yukawa, • 0.2 Regge, dual resonance ( → strings– Ne)utrinoless double beta0.1 decay (ββ0ν) (inverted or degenerate 0 Asymptoticspectra) freedom (weak 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 • x coupling at high energy)

Figure 16.4: Distributions of x times the unpolarized parton distributions f(x) YYoichihirrooNamNambubuSympSymposiumosium(April(wh(Aprile21,re 2005)21,f =2005)uv,dv,u, d, s, c, g) using thPeaulMRSLangacPaulT2001kerLangac(Penn)pkaerrameterization(Penn) [29,13](with 2 2 uncertainties for uv, dv,andg) at a scale µ =10GeV .

NYS APS (October 15, 2004) Paul Langacker (Penn) June 16, 2004 14:04 6 40. P lots of cross sections and related quantities

σ and R in e+e− Collisions -2 10 ω -3 φ J/ψ 10 ψ(2S)

-4 ρ 10 ρ Z

-5 10 mb

-6 10 σ

-7 10

-8 10 2 Ne1 utrinos Implications/questions10 10

J/ψ ψ(2S) 10 3 R Z Key constituent of the Universe • 10 2 Why are the masφ ses so small? • ω – Planck/GUT scale? e.g., seesaw 10 or generalization, m m2 /M ρ ν ∼ D N

1 Are theρ neutrinos Dirac or • Majorana? -1 S GeV 10 – Neutrinoless double beta decay 2 (ββ0ν) (invert1 ed or degenerate10 10

spectra) + − + − + − Figure 40.6: World data on the total cross secti+on of e e → hadrons and the ratio R(s) = σ(e e → hadrons, s)/σ(e e → µ+µ−, s). σ(e+e− → hadrons, s) is the σexpe(rimeentalecr−oss sectionhadrcorrected foons)r initial state radiation and electron-positron vertex loops, σ(e+e− → µ+µ−, s)R= 4πα2(s)/3s. Data errors ar→e total below 2 GeV and statistical above 2 GeV. The curves are an educative guide: the broken one is a≡naive quσark-(paerto+n meodel predictioµn a+nd µthe solid)one is 3-loop pQCD prediction (see “Quantum chromodynamics” section of this Review, Eq. (9.12) or, for−more details, K. G−. Chetyrkin et al., hep-ph/0005139, p.3, Eqs. (1)- (3)). Breit-Wigner parameterizations of J/ψ, ψ(2S), and Υ(nS→), n = 1..4 are also shown. The full list of references to the original Yoichiro Nambu Symposium (April 21, 2005) Paul Langacker (Penn) data and the details of the R ratio extraction from them can be found in hep-ph/0312114. Corresponding computer-readable data ﬁles are available at http://pdg.ihep.su/xsect/contents.html. (Courtesy of the COMPAS(Protvino) and HEPDATA(Durham) Groups, March 2004. Corrections by P. Janot (CERN) and M. Schmitt (Northwestern U.))

Yoichiro Nambu Symposium (April 21, 2005) Paul Langacker (Penn) Quark model/ color • Low energy symmetries • (+ realization, breaking) (SU(3) SU(3) ) L× R

Hadronic models: Yukawa, • Regge, dual resonance ( → strings)

Asymptotic freedom (weak • coupling at low energy) Neutrinos Implications/questions9. Quantum chromodynamics 17

required, for example, to facilitate the extraction of CKM elements from measurements Relation9. Quantumof “running”chrof chomoarm adndynamicsbottomαdecas7y atrates. SeediRef.ﬀere169 fornta recenscalest review.

Key constituent of the Universe • Average Hadronic Jets Why are the mase+sese- ratesso small? • Photo-production 0.3 – Planck/GUTFragmentationscale? e.g., seesaw

Z width 2 )

or generalization, m m µ /M ν D( N ep event shapes 0.2s ∼ ! YPolarizedoichir DISo Nambu Symposium (April 21, 2005) Paul Langacker (Penn) ArDeepe Inelasticthe Scatteringneutr (DIS) inos Dirac or • Majorana? ! decays 0.1 Spectroscopy (Lattice) – Neutrinol" decay ess double beta decay (ββ ) (inverted or degenerate 0ν 0 2 0.1 0.12 0.14 1 10 10 spectra) GeV #s(MZ) µ

Figure 9.1: Summary of the value of αs(MZ) from various proFigucesses.re 9.2:TheSummaryvalues of the values of αs(µ)atthevaluesofµwhere they are shown indicate the process and the measured value of α extrapmeasured.olated to Tµhe= lMines. show the central values and the 1σ limits of our average. s Z ± The error shown is the total error including theoretical uncertainThetiefis.gureTheclaearlveragey shows the decrease in αs(µ) with increasing µ. The data are, + quoted in this report which comes from these measurements is ialnsoincreasishown.ngSeeordertexotf µ, τ width, Υ decays, deep inelastic scattering, e e− event for discussionYoicof errors.hiro Nambu Symposium (April 21, 2005)shapes at 22 GeV from the JADE data, shapes at PTaulRISTLangacAN at 58kerGeV,(Penn)Z width, + and e e− event shapes at 135 and 189 GeV. extracted [44,45] are consistent with the theoretical estimates. If the nonperturbative terms are omitted from the fit, the extracted value of αs(mτ ) decreases by 0.02. 9.13. Conclusions∼ For αs (mτ )=0.35 the perturbative series for Rτ is Rτ 3.058(1+0.112+0.064+0.036). The size (estimated error) of the nonperturbative term ∼is 20% (7%)The ofneedthe forsizeborevitf thye has meant that many other important topics in QCD 3 3 order αs term. The perturbation series is not very well convergephnetn;oimef thneologyorderhaαvsetehrmad to be omitted from this review. One should mention in 4 is omitted, the extracted value of αs(mτ ) increases by 0.05. Thparte ordiculerarαsthtermstudyhas bofeenexclusive processes (form factors, elastic scattering, ...), the estimated [46] and attempts made to resum the entire series [47,be48]ha.viorTheseof questarksimatanes dcangluons in nuclei, the spin properties of the theory, and QCD be used to obtain an estimate of the errors due to these unkenoffectwns tinermshadron[49,50]spect. Wroscope y. assign an uncertainty of 0.02 to αs(mτ ) from these sources. We have focused on those high-energy processes which currently offer the most ± Rτ can be extracted from the semi-leptonic branching ratioquantitativfrom the teesrteslationof perturbative QCD. Figure 9.1 shows the values of αs(MZ ) deduced Rτ =1/(B(τ eνν) 1.97256); where B(τ eνν) is measured directly or extracted from the lifetime→ , the −muon mass, and the mu→on lifetime assuming universality of lepton September 8, 2004 15:07 couplings. Using the average lifetime of 290.6 1.1fsandaτmass of 1776.99 0.29 ± ±

September 8, 2004 15:07 Neutrinos Implications/questions QuQuantumantumElectroElectroddynamynamicsics

Key constituent of the Universe •

1 1 ExperWhyiment are the masses Vsoaluesofmallα−? Difference from α− (ae) • 1 9 1 ExperiDementviation from gyromagnetic Value137of.035α−999 58 (52) [3.8 10− ] –Difference from α− (ae) × 9 Deviationratio,from– aPlegyr=anck/GUTom(gagne2)ti/c2 for e−scale?137.035e.g.999 ,58s(52)eesaw[3.8 10− ] – − 2 × 8 4 ratio,ac aJosephsone =o(gr generalieff2)ect/2 for ez−ation, m137ν.035 988m0 (51)/MN[3.7 10− ] (0.116 0.051) 10− − D × 8 ± × 4 h/mn (mn is the neutron mass) 137.036∼011 9 (51) [3.7 10 8] ( 0.123 0.051) 10 4 ac Josephson effect 137.035 988 0 (51) [3.7 ×10−− ] −(0.116± 0.051)× 10−− from n beam × 8 ± × 4 h/mn (mn is the neutron mass) 137.036 011 9 (51) [3.7 10 ] ( 0.123 0.051) 10 × −8 − ± × 4− fromHypnerfibAreamneestructurethein neutrinos137.035D993irac2 (83) or[6.0 10− ] (0.064 0.083) 10− + × ± × •muonium, µ e− 8 4 Hyperfine sMajotructureranin a? 137.035 993 2 (83) [6.0 10−8] (0.064 0.083) 104− Cesium D+1 line 137.035 992 4 (41) [3.0× 10− ] (0.072 ±0.041) ×10− muonium, µ e− × ± × Cesium D –lineNeutrinoless doubl137.e035 b992eta4 (41)decay[3.0 10 8] (0.072 0.041) 10 4 1 × − ± × − (ββ0ν) (inverted or degenerate spectra)

Yoichiro Nambu Symposium (April 21, 2005) Paul Langacker (Penn)

Yoichiro Nambu Symposium (April 21, 2005) Paul Langacker (Penn) Neutrinos Implications/questions The Electroweak Theory

QED and weak charged current •Key constituent of the Universe • uniﬁed Why are the masses so small? • Weak neutral current predicted • – Planck/GUT scale? e.g., seesaw Stringentor generalitzesation,ts ofmwnc, mZ-p2 /oleM • ν D N and beyond ∼ Are the neutrinos Dirac or • Majorana? – Neutrinoless double beta decay (ββ0ν) (inverted or degenerate spectra)

YoicNYShiro APSNambu(OctobSymper osium15, 2004)(April 21, 2005) PPaulaulLangacLangackerker(P(Penenn)n) NeutrinosLEP combined:Implic e+ate! i"ons/questions hadrons(#)

%%% LEP1 $s´/s > 0.10 %%% LEP2 $s´/s > 0.10 %%% LEP2 $s´/s > 0.85 Key constituent10 of the Universe •

Why are the ] masses so small? nb • [ 1

– Planck/GUT scale? e.g., seesaw 2 or generalizhadron ation, mν m /MN & -1 ∼ D 10 Are the neutrinos Dirac or • Majorana? -2 10 – Neutrinoless double beta decay 75 100 125 150 175 (ββ0ν) (inverted or degen% erate spectra) $s [GeV]

Yoichiro Nambu Symposium (April 21, 2005) Paul Langacker (Penn) Winter 2004

Measurement Fit |Omeas!Ofit|/"meas Neutrinos Implications/questions0 1 2 3 (5) #$had(mZ) 0.02761 ± 0.00036 0.02768

mZ [GeV] 91.1875 ± 0.0021 91.1873

%Z [GeV] 2.4952 ± 0.0023 2.4965 0 nb 41.540 0.037 41.481 Key constituent"had [ of] the Universe± • Rl 20.767 ± 0.025 20.739 0,l Afb 0.01714 ± 0.00095 0.01642 Why are theAmas(P ) ses so0.1465small ± 0.0032? 0.1480 • l & R 0.21638 0.00066 0.21566 – Planck/GUTb scale? e.g.± , seesaw R 0.1720 ± 0.0030 0.1723 c 2 or generaliz0,bation, mν m /MN Afb 0.0997 ± 0.0016D 0.1037 0,c ∼ Afb 0.0706 ± 0.0035 0.0742 Are the Abneutrinos0.925D ± i0.020rac or0.935 • A 0.670 0.026 0.668 Majorana? c ± Al(SLD) 0.1513 ± 0.0021 0.1480 2 lept – Neutrinolesssin 'effdoubl(Qfb) 0.2324e beta ± 0.0012deca0.2314y m [GeV] 80.425 ± 0.034 80.398 (ββ0ν) (invertW ed or degenerate GeV 2.133 0.069 2.094 spectra) %W [ ] ± mt [GeV] 178.0 ± 4.3 178.1

0 1 2 3

Yoichiro Nambu Symposium (April 21, 2005) Paul Langacker (Penn) Neutrinos Implications/questions SM correct and unique to zeroth • 6 approx. (gauge principle, group, Theory uncertainty (5) representations) !#had = 5Key constituent0.02761of±0.00036the Universe • 0.02747±0.00012 4 incl. low Q2 data SM correct at loop level (renorm • Why are the masses so small? gauge theory; m , α , M ) 2 • t s H 3 !" – Planck/GUT scale? e.g., seesaw 2 2 or generalization, mν mD/MTeVN physics severely constrained ∼ • (uniﬁcation vs compositeness) 1Are the neutrinos Dirac or • MajoExcludedrana? Preliminary 0 Precise gauge couplings (gauge 20 100 400 • – Neutrinoless double beta decuniﬁcatiay on) mH [GeV] (ββ0ν) (inverted or degenerate spectra)

Yoichiro Nambu Symposium (April 21, 2005) Paul Langacker (Penn)

NYS APS (October 15, 2004) Paul Langacker (Penn) Neutrinos Implic1.5 ations/questions Heavy B decays and CP excluded area has CL < 0.05 • violation m 1 # d – CKM (quark mixing) sin 2! Key constituent of the Universe m m • description of CP # s & # d 0.5 breaking B ! "" Why are the masses so small? % $ • K – Unitarity triangle & ! – Planck/GUT scale? e.g.' , 0seesaw – Search for new physics |V /V | or generalization, m m2 /Mub cb ν ∼ D N – Baryogenesis? -0.5 $ Are the neutrinos Dirac or K • Majorana? -1

C K M – Neutrinoless double beta decf ia t t ye r Winter 2004 B ! "" (ββ0ν) (inverted or degen-1.5 erate spectra) -1 -0.5 0 0.5 1 1.5 2 "

Yoichiro Nambu Symposium (April 21, 2005) Paul Langacker (Penn)

NYS APS (October 15, 2004) Paul Langacker (Penn) Neutrinos Implications/questions Problems with the Standard Model

Key constituent of the Universe • Lagrangian after symmetry breaking:

Why are the masses so small? miH • = Lgauge + LHiggs + ψ¯i i ∂ mi ψi L ! − − ν – Planck/GUT scale? e.g.,!iseesa"w # g 2 g or generalization, mµν m /µMN+ µ µ JW Wµ− +DJW†Wµ eJQAµ JZZµ −2√2 ∼ − − 2 cos θW $ % Are the neutrinos Dirac or • MajoStandarana?rd model: SU(2) U(1) (extended to include ν masses) + × QCD + general relativity – Neutrinoless double beta decay (ββ ) (inverted or degenerate Mathemati0ν cally consistent, renormalizable theory spectra)

16 Correct to 10− cm

Physics at LHC (July 16, 2004) Paul Langacker (Penn) Yoichiro Nambu Symposium (April 21, 2005) Paul Langacker (Penn) Neutrinos Implications/questions However, too much arbitrariness and ﬁne-tuning: O(27) parameters (+ 2 for Majorana ν), and electric charges

KeyGaugeconstituentProblemof the Universe • • – complicated gauge group with 3 couplings Why– acharerthege quantimasseszationso (smallq =? q ) unexplained • | e| | p| – Pl–anck/GUTPossible solutiscale?ons: e.g.strings;, seesawgrand uniﬁcation; magnetic monopoles (partial); anomaly constraints (partial) or generalization, m m2 /M ν ∼ D N Fermion problem Ar•e the neutrinos Dirac or • Majo– ranFermia?on masses, mixings, families unexplained – Neutrino masses, nature? Probe of Planck/GUT scale? – Ne– utrinolCP violessationdoublinadeequatebetato expldecainay baryon asymmetry – Possible solutions: strings; brane worlds; family symmetries; (ββ0ν) (inverted or degenerate spectrcompa)ositeness; radiative hierarchies. New sources of CP violation.

NYS APS (October 15, 2004) Paul Langacker (Penn) Yoichiro Nambu Symposium (April 21, 2005) Paul Langacker (Penn) Neutrinos Implications/questions

Higgs/hierarchy problem • – Expect M 2 = O(M 2 ) Key constituentH of the UniverseW • – higher order corrections: δM 2 /M 2 1034 Why areHthe Wmas∼ses so small? • Possible solutions: supersymmetry; dynamical symmetry breaking; – Planck/GUT scale? e.g., seesaw large extra dimensions; Little Higgs; anthropically motivated ﬁne- or generalization, m m2 /M tuning (split supersymmetry)ν ∼ (landD scape)N Are the neutrinos Dirac or • Strong CP problem Majo• rana? θ 2 ˜ – Can add 32π2 gsF F to QCD (breaks, P, T, CP) – Neutrinoless doubl9 e beta decay 3 – dN θ < 10− , but δθ weak 10− (ββ )⇒ (inverted or degen| erate∼ – Possi0ν ble solutions: spontaneously broken global U(1) (Peccei- spectrQuinn)a) axion; unbroken global U(1) (massless u quark); ⇒ spontaneously broken CP + other symmetries

Yoichiro Nambu Symposium (April 21, 2005) Paul Langacker (Penn)

Yoichiro Nambu Symposium (April 21, 2005) Paul Langacker (Penn) Neutrinos Implications/questions

Graviton problem • Key– gravitconstituenty not unifiedof the Universe • – quantum gravity not renormalizable Why– cosmare ologithe mascal sesconstant:so smallΛ? = 8πG V > 1050Λ (10124 • SSB N ! " obs – Plfoanck/GUTr GUTs, stsricale?ngs) e.g., seesaw –orPgeneraliossible szolutionsation, m: m2 /M supergravity and νK∼aluzaDKleinNunify ∗ strings yield finite gravity. Are ∗ the neutrinos Dirac or • Λ? Anthropically motivated fine-tuning (landscape)? Majo∗rana? – Neutrinoless double beta decay (ββ0ν) (inverted or degenerate spectra)

Yoichiro Nambu Symposium (April 21, 2005) Paul Langacker (Penn)

Yoichiro Nambu Symposium (April 21, 2005) Paul Langacker (Penn) Neutrinos Implications/questions

Beyond the Standard Model Key constituent of the Universe • WhyTheare Whimthe masper:sesA sonewsmalllaye?r at the TeV scale • • – Planck/GUTThe Hybrid: slocale?w fundamentale.g., seesascalwe/large extra dimensions • 2 or generalization, mν mD/MN ∼ 1/2 The Bang: uniﬁcation at the Planck scale, M = G− 1019 • P N ∼ Are GeVthe neutrinos Dirac or • Majorana? – Neutrinoless double beta decay (ββ0ν) (inverted or degenerate spectra)

Yoichiro Nambu Symposium (April 21, 2005) Paul Langacker (Penn)

NYS APS (October 15, 2004) Paul Langacker (Penn) Neutrinos Implications/questions Compositeness

Onion-like layers • Key constituent of the Universe • Composite fermions, scalars (dynamical sym. breaking) • Why are the masses so small? Not like to atom nucleus +e− p + n quark • • → → → – Planck/GUT scale? e.g., seesaw At most one more layer accessible (Tevatron, LHC, ILC) or•generalization, m m2 /M ν ∼ D N Rare decays (e.g., K µe) Are• the neutrinos →Dirac or • Eﬀects (typically, few %) expected at LEP/SLC, WNC Majo•rana? – Neutrinolanomalessous VdoublV V ,e nebwetapardtieccles,ay future W W W W , FCNC, • → (ββEDM0ν) (inverted or degenerate spectra) Recent variant: Little Higgs •

NYS APS (October 15, 2004) Paul Langacker (Penn)

Yoichiro Nambu Symposium (April 21, 2005) Paul Langacker (Penn) Neutrinos Implications/questions Large extra dimensions (deconstruction, brane worlds)

Key constituent of the Universe • Can be motivated by strings, but • new dimensions much larger than 1 33 WhyM −are the10−mascmses so small? • P ∼ – Planck/GUT scale? e.g., seesaw Fundamental scale MF 2 • or generalization, mν ¯ m ∼/MN 1 100 TeV ∼MP l D= − # 18 1/√8πGN 2.4 10 GeV Are the neutr∼ i×nos Dirac or • – Assume δ extra dimensions Majorana? δ with volume V M − δ & F – Neutrinoless double beta decay M¯ 2 = M 2+δV M 2 (ββ0ν) P(linvertFed δor°enF erate spectra) (Introduces new hierarchy problem)

NYS APS (October 15, 2004) Paul Langacker (Penn) Yoichiro Nambu Symposium (April 21, 2005) Paul Langacker (Penn) Neutrinos Implications/questions Black holes, graviton emission at Particle Ph•ysics Probes Of Extra Spacetime Dimensions 29 colliders!

Key constituent of the UniverseMacroscopic gravity eﬀects • • Why are the masses so small? Astrophysics • • – Planck/GUT scale? e.g., seesaw or generalization, m m2 /M ν ∼ D N Are the neutrinos Dirac or • Majorana? – Neutrinoless double beta decay (ββ0ν) (inverted or degenerate spectra)

Yoichiro Nambu Symposium (April 21, 2005)Figure 7: 95% conﬁdence level upper limits on the sPtraulengthLangacα (relaktierve (Pto enn)Newtonian gravity) as a functioNYSn of tAPShe ran(gOctobe λ of aerddi15,tiona2004)l Yukawa interactions. The region excluded by previous Paul Langacker (Penn) experiments (55,56,61) lies above the curves labeled Irvine, Moscow and Lamoreaux, respectively. The most recent results (60) correspond to the curves labeled E¨ot-Wash. The heavy dashed line is the result from Ref. (60), the heavy solid line shows the most recent analysis that uses the total data sample. Neutrinos Implications/questions

Unification Key constituent of the Universe • Why aUnificre theatmasion sesof intsoeractismallons? • • – Planck/GUT scale? e.g., seesaw Grand desert to unification (GUT) or Planck scale or•generalization, m m2 /M ν ∼ D N Elementary Higgs, supersymmetry (SUSY), GUTs, strings Are • the neutrinos Dirac or • Majorana? Possibility of probing to MP and very early universe – Ne•utrinoless double beta decay (ββ0ν) (inverted or degenerate spectra)

Yoichiro Nambu Symposium (April 21, 2005) Paul Langacker (Penn)

NYS APS (October 15, 2004) Paul Langacker (Penn) Neutrinos Implications/questions

Supersymmetry Key constituent of the Universe • Fermion boson symmetry Why• are the↔masses so small? • Motivations –•Planck/GUT scale? e.g., seesaw 2 o–r generalistabilizezwation,eak scmaleν mMD/MN< O(1 TeV) ⇒∼ SUSY – supergravity (gauged supersymmetry): uniﬁcation of gravity Are the neutrinos Dirac or • (non-renormalizable) Majo– rancouplia? ng constants in supersymmetric grand uniﬁcation – Ne– utrinoldecoupliessng ofdoublheavye bpaetarticlesdec(paryecision) (ββ0ν) (inverted or degenerate spectra)

Yoichiro Nambu Symposium (April 21, 2005) Paul Langacker (Penn)

NYS APS (October 15, 2004) Paul Langacker (Penn) Neutrinos Implications/questions Consequences • 1000 !Z, "had, Rl, Rq – additional charged and neutral asymmetries Key constituent of the Universe # scattering 500 MW Higgs particles m • t – M 2 < cos2 2βM 2 + H.O.T. Why areH0the masses so Zsmall? all data 4 2 90% CL • (O(mt)) < (150 GeV) , 200 – Plconsianck/GUTstent withscale?LEPe.g., seesaw

2 100

or generalization, mν m /MN [GeV] cf., standard model: MDH0 < H ∗ ∼ M 1000 GeV Are the neutrinos Dirac or 50 • Majorana? excluded – Neutrinoless double beta decay 20 (ββ0ν) (inverted or degenerate 10 spectra) 100 120 140 160 180 200 mt [GeV]

Yoichiro Nambu Symposium (April 21, 2005) Paul Langacker (Penn)

NYS APS (October 15, 2004) Paul Langacker (Penn) 800 m [GeV] Neutrinos Implications/questions 700 Superpartners •

600 g˜ – q q˜, scalar quark t˜2 ⇒ u˜ , d˜ L R ˜ ˜ u˜R, d˜L b2 – ! !, scalar lepton 500 Key constituent of the Universe˜b1 ⇒ • – W w˜, wino 0 0 ± ⇒ 400 H , A H 0 ± χ˜04 χ˜2 t˜1 χ˜3 – typical scale: several hundred Why are the masses so small? GeV 30•0 – LSP: cold dark matter 200 – Planck/GUT˜lL τ˜2 scale? e.g., seesaw ν˜ 0 ± l χ˜2 χ˜1 2 candidate ˜l or generaliR zτation,˜1 mν m /MN h0 D 100 0 χ˜1 ∼ – SUSY breaking large m ⇔ t – May be large FCNC, EDM, 0 Are the neutrinos Dirac or • ∆(g 2) Majorana? µ − – Neutrinoless double beta decay (ββ0ν) (inverted or degenerate spectra)

NYS APS (October 15, 2004) Paul Langacker (Penn) Yoichiro Nambu Symposium (April 21, 2005) Paul Langacker (Penn) Neutrinos Implications/questions Grand Uniﬁcation

) µ ( -1 i 60 Key Unifyconstituentstrongof theSUUniverse(3) and ! SM • 50 ! World Average • 1 electroweak SU(2) U(1) 40 ! Why are the masses so small× ? 2 • in simple group, broken at 30 16 – Planck/GUT10 GeVscale? e.g., seesaw20 !3 ! (M )=0.117±0.005 ∼ S Z 2 2 or generalization, mν m /MN10 sin "__=0.2317±0.0004 ∼ D MS 0 Gauge uniﬁcation (only in 5 10 15 • 1 10 10 10 µ (GeV)

Are the neutrinos Dirac or)

supersymmetric version) µ ( -1 • i 60 Majorana? ! MSSM 50 68% World Average CL !1 – Neutrinoless double beta decay40 !2 (ββ0ν) (inverted or degenerate30

spectra) 20 !3

10 U.A. W.d.B H.F. 0 5 10 15 1 10 10 10 µ (GeV)

Yoichiro Nambu Symposium (April 21, 2005) Paul Langac ker (Penn)

NYS APS (October 15, 2004) Paul Langacker (Penn) 1636

Neutrinos Implications/questions mode exposure !Bm observed B.G. (ktï yr) (%) event Seesa+w 0model for small mν (but • p " e + # 92 40 0 0.2 54 + 0 why are+ m0 ixings large?) p " e # p " µ + # 92 32 0 0.2 43 + + e $ p " e + $ 92 17 0 0.2 23 + + e ' p " µ + $ 92 90 0.213 + 0 __ e & KeyQun "a rk-%c +on $leptonstituent45 (q21 ofl5)theuni9ﬁUniversecati on 5.6 + 0 •• p " e+ + & 92 4.2− 0 0.4 5.6 e K ( cha+ rge quantization) µ+ #0 ⇒p " e + ' 92 2.9 0 0.5 3.8 + + µ $ Whyp " e a +re ( the92 mas73 ses0 so0.1small98 ? µ+ ' + + 0 • qp " __µl +mas ( s 92relations61 0(work0.2only 82for µ & • p− + K+ 92 22 + 0 " +% + µ K –thirdPlKanck/GUT"%famiµ (spectrum)ly in simples34 stcale?ver-- sions)-- e.g. 4.2, seesaw__ + + % # prompt ( + µ 8.6 0 0.7 11 2 __ + orK+ generali+ 0 zation, 6.0 0 m 0.6 m 7.9 /M % & __"# # ν D N__ + Protonn " % + K0 deca92y? (simplest versions∼ 2.0 % K • K0"#0#0 6.9 14 19.2 3.0 + - 0 + - n " e # excluded)K "# # 5.5 20 11.2 0.8 + - + 0 e & Arpe e + theK 92 neutrinos D 10.7irac or+ - " 0 0 0 µ # • K "# # 9.2 1 1.1 8.7 + - Majo0 ran+ - a? µ & DouK bl"#et-triplet# problem? __ 0 % # • 2-ring 7.9 5 3.6 4.0 __ 3-ring 1.3 0 0.1 1.7 __% $ – pNe +utrinol + K0 92ess double beta13.9 deca%y ' SK " 0µ 0 0 __ StringK "# # embedding? 5.4 0 (b0.4reaking, 7.1 % &0 IMB3 • (β0 β+ - ) (inverted or degenerate__ 0 famiKli"#es0#νmay be entangled in extra % K KAM sp ectr2-ring a) 7.0 3 3.2 4.9 Soudan2 dimen 3-ringsions) 2.8 0 0.3 3.7 31 32 33 34 10 10 10 10 lifetime limit (years)

Yoichiro Nambu Symposium (April 21, 2005) Paul Langacker (Penn)

YoicFhiigro. Nam1. buTSymphe oosiumbtaine(Aprild life21,time2005)limit of nucleons from SK–I (leftPaulﬁgurLangace) aknder (Ptheenn)ir comparisons with other experiments (right ﬁgure).

6. References

1. J. Ellis et al., Nucl. Phys. B 202, 43 (1982) 2. Y.Fukuda et al., Phys. Rev. Lett. 81, 1562 (1998) 3. Y.Fukuda et al., Nucl. Instr. Meth. A 501, 418 (2003) 4. H. Georgi and S. L. Glashow, Phys. Rev. Lett. 32, 438 (1974) 5. Y. Hayato et al., Phys. Rev. Lett. 83, 1529 (1999) 6. Jogesh C. Pati and Abdus Salam, Phys. Rev. Lett. 31, 661 (1973) 7. For example, Jogesh C. Pati, hep-ph/ 0005095. 8. N. Sakai and T. Yanagida, Nucl. Phys. B 197, 533 (1982) 9. M. Shiozawa et al., Phys. Rev. Lett. 81, 3319 (1998) 10. M. Shiozawa, PhD thesis, University of Tokyo (1999) 11. S. Weinberg, Phys. Rev. D 26, 287 (1982) Neutrinos Implications/questions Superstrings

Finite, “parameter-free” “theory • Key constituent of the Universe • of everything” (TOE), including quantum gravity Why are the masses so small? • – 1-d string-like object –– PlAppanck/GUTears pointlikscale?e for resole.g.ution, seesaw 1 33 > M − 10− cm 2 or generaliP ∼ zation, mν mD/MN – Vibrational modes pa∼rticles → Ar– eConsithestent neutrin inos10 sDpace-irac or • time dimensions 6 must Majorana? → 1 compactify to scale MP− –– Ne4-diutrinolm supessersymdoublmetrice bgaugeeta decay (theoββ0ryν)belo(invertw MPed or degenerate – spMaectry ala)so be solitons (branes), terminating open strings

NYS APS (October 15, 2004) Paul Langacker (Penn) Yoichiro Nambu Symposium (April 21, 2005) Paul Langacker (Penn) Neutrinos Implications/questions

Problems • – Which compactiﬁcation manifold? Key constituent of the Universe • – Supersymmetry breaking? Cosmological constant? – Many moduli (vacua). Landscape ideas - is there any Why are the masses so small? • predictability left? – –PlRelanck/GUTation to ssupcale?ersymme.g.etri, cseesastandaw rd model, GUT? or generalization, m m2 /M ν ∼ D N Need theoretical progress and hints from experiment •Are the neutrinos Dirac or • – TeV scale remnants, such as Z!, exotics Majorana? – SUSY breaking patterns – –NeNeutrinoled veryessprecisedoublemasbseseta anddeccouplingsay International Linear → (βColβ0νli)der(inverted or degenerate spectra)

Yoichiro Nambu Symposium (April 21, 2005) Paul Langacker (Penn)

Yoichiro Nambu Symposium (April 21, 2005) Paul Langacker (Penn) Neutrinos Implications/questions Future/present Experiments

KeyHighconenergystituentcoloflidersthe: theUniverseprimary tool • • – The TEVATRON; Fermilab, 1.96 TeV pp¯ , exploration Why are the masses so small? • – The Large Hadron Collider (LHC); CERN, 14 TeV pp, high – Planck/GUTluminosity, sdisccale?overye.g.(Disc, soveeesary wmachine for supersymmetry, Rp violation, string remnants (e.g.,2Z!, exotics); or compositeness, dynamical or generalization, mν mD/MN symmetry breaking, Higgl∼ess theories, Little Higgs, large extra dimensions, ) Are · ·the· neutrinos Dirac or • Majo– ranThea?International Linear Collider (ILC), in planning; + 500 GeV-1 TeV e e−, cold technology, high precision studies – Neutrinol(Precisionessparameterdoubls eto mapbetabackdtoecsatrying scale) (ββ0ν) (inverted or degenerate Also, CP violation (B decays, electric dipole moments), ﬂavor changing •spectra) neutral currents, neutrino physics

Yoichiro Nambu Symposium (April 21, 2005) Paul Langacker (Penn) Yoichiro Nambu Symposium (April 21, 2005) Paul Langacker (Penn) Neutrinos Implications/questions

33 +28 Neutrinos as a Unique Probe: 10− 10 cm − Key constituent of the Universe • Particle Physics Why• are the masses so small? • – νN, µN, eN scattering: existence/ properties of quarks, QCD – Planck/GUT scale? e.g., seesaw – Weak decays (n pe−ν¯e2, µ− e−νµν¯e): Fermi theory, parity or generalization, m→ν mD/MN→ violation, mixing ∼ Are– Netheutral neutrcurrentinos, Z-pole,Diracatomiocrparity: electroweak unification, • Majoranfielda?theory, mt; severe constraint on physics to TeV scale – Neutrino mass: constraint on TeV physics, grand unification, – Neutrinoless double beta decay 2 superstrings, extra dimensions; seesaw: mν mq/MGUT (ββ0ν) (inverted or degenerate ∼ spectra)

Yoichiro Nambu Symposium (April 21, 2005) Paul Langacker (Penn) Xalapa (August, 2004) Paul Langacker (Penn) 2 3 4 1 10 10 10 10

Neutrinos Implications/questions Solar/atmospheric • neutrino experiments

Key– Neconutrinosstituenthaveof thetinyUniverse • masses (but large mixings) Why are the masses so small? • – Standard Solar model – Plconﬁrmedanck/GUT scale? e.g., seesaw1.8 1.8 2 –orFirstgeneralioscilzation,lation mdips m /M 1.6 1.6 ν ∼ D N observed! (QM on 1.4 1.4 Are largethescale)neutrinos Dirac o1.2r 1.2 • 1 1 Majorana? 0.8 0.8 – Neutrinoless double beta deca0.6y 0.6 0.4 0.4 (ββ ) (inverted or degenerate 0ν Data/Prediction (null osc.) 0.2 0.2 spectra) 0 2 3 4 0 1 10 10 10 10 L/E (km/GeV)

Yoichiro Nambu Symposium (April 21, 2005) Paul Langacker (Penn) NYS APS (October 15, 2004) Paul Langacker (Penn) Neutrinos Implications/questionsCDHSW 3 ν Patterns CHORUS • NOMAD

– Solar: LMA (SNO, 0 KARMEN2 NOMAD 10 LSND CHORUS Kamland) Key constituent of the Universe Bugey BNL E776 • 2 5 4 SuperK – ∆m (10− 10− ) CHOO erde ! ∼ − Why are2 the masses so small? –3 Z PaloV • eV for LMA 10

– Planck/GUT scale? e.g., seesa] w LMA

2 2 – Atmospheric: ∆mAtm ∼ 2 V or generali3 zation,2 mν m /e MN KamLAND 3 10− eV , near- D [ SMA ∼ × 2 maximal mixing –6 m 10 Are the neutrinos Dirac ∆ or • Majo– Reactorana?r: Ue3 small LOW νe↔νX νµ↔ντ ν ↔ν – Neutrinoless double beta d1ec0–a9y e τ νe↔νµ (ββ0ν) (inverted or degenerate VAC spectra)

10–12 10–4 10–2 100 102 tan2θ Yoichiro Nambu Symposium (April 21, 2005) Paul Langacker (Penn) Neutrinos Implications/questions Neutrino Implications/questions

Key constituent of the Universe • Key constituent of the Universe 6 6 6 • νL v = φ νL νL 3 2 ! " @@ @@ 1 h Why are the masses so small? @@ @@ Why are the masses2so small? c • N mD = hv ν ν ? • 1 3 R 6 R 6 L ––PlPlanck/GUTanck/GUT sscale?cale?norme.g.ale.g., inverteds,eesaseesaw w 2 2 Dirac Majorana oorrgeneraligeneralizzation,ation,mmν mm/M/NM ν∼∼ D D N Are the neutrinos Dirac or •Are the neutrinos Dirac or • Majorana? Majorana? – Neutrinoless double beta decay – Ne(βutrinolβ0ν) (essinvertdoubled ore degenbetaeratedecay (βspβectr0ν)a) (inverted or degenerate spectra)

Yoichiro Nambu Symposium (April 21, 2005) Paul Langacker (Penn)

Yoichiro Nambu Symposium (AprilNYS21,APS2005)(October 15, 2004) Paul LangacPkauler Langac(Penn)ker (Penn) Neutrinos Implications/questions What is the spectrum: number, 6 6 6 • νL v = φ νL νL mass scale/pattern, mixings 3 2 ! " 1 @@ @@ degeneh rate @@ @@ – Scale: β decay (KATRIN), ββ0ν, 2 c N mD = hv ν ν ? Keylargeconscalstituente structureof the(SDSSUniverse) 1 3 R 6 R 6 L • – Mixings: reactor, long baseline normal inverted Dirac Majorana oscillation experiments, Solar Why are the masses so small? • – Pattern: long baseline, ββ0ν, supernova –– PlNuanck/GUTmber: MiniBosoNcale?E e.g., seesaw or generalization, m m2 /M ν ∼ D N Leptogenesis? • Are the neutrinos Dirac or • Relic neutrinos? • Majorana? – Indirect: Nucleosynthesis, large – Nescalutrinole structure.ess doublDirect?e beta(Z-decay (burst?ββ0ν)) (inverted or degenerate spectra) NYS APS (October 15, 2004) Paul Langacker (Penn)

NYS APS (October 15, 2004) Paul Langacker (Penn)

NYS APS (October 15, 2004) Paul Langacker (Penn) Yoichiro Nambu Symposium (April 21, 2005) Paul Langacker (Penn) Neutrinos Implications/questions The Universe

KeyThe concoconstituentrdance of the Universe •• – 5% matter (including dark Whybaryaons):re theCmasMB,sesBBN,so smallLyman? • α – Planck/GUT scale? e.g., seesaw – 25%or generalidark zation,matterm(galaximes,2 /M clusters, CMB, lensing)ν ∼ D N – 70% dark energy (Acceleration Are the neutrinos Dirac or • (Supernovae), CMB (WMAP)) Majorana? – Neutrinoless double beta decay (ββ0ν) (inverted or degenerate spectra)

NYS APS (October 15, 2004) Paul Langacker (Penn) Yoichiro Nambu Symposium (April 21, 2005) Paul Langacker (Penn) What is the dark matter? • – Lightest neutralino in supersymmetry (if R parity conserved)? Axion? – Direct searches: LHC, ILC; cold dark matter searches; high energy annihilation ν’s – Gravitation lensing (SNAP), CMB (Planck)

What is theNedarkutrinosenergy? Implications/questions • – Vacuum energy (cosmological constant); time varying ﬁeld (quintessence)? Key– Highconsptituentrecision ofsuptheernovaUniversesurvey (SNAP); • CMB (Planck) Expansion History of the Universe

Perlmutter, Physics Today (2003)

NYSWhyAPS (aOctobre theer 15, 2004)masses so small? Paul Langacker (Penn) expands forever • relative 1

0.1 s 0.01 se 0.001 p 1.5 brightness 0.0001 lla – Planck/GUT scale? e.g., seesaw co or generalization, m m2 /M ν ∼ D N Are the neutrinos 1.0Dirac or 0 • Majorana? 0.25 After inflation, d 0.5 the expansion either... te a 0.75 ed r redshift t e – Neutrinoless doublScale of the Universe e b0.5eta decay ra l 1 le e

Relative to Today's Scale e cc c a e 1.5 n d (ββ ) (inverted or degeneratehe 2 0ν , t s ed y 2.5 rat a 3 le w spectra) e l c a e t d r past today future s o r . i 0.05 . 0.0 f . –20 –10 0 10 Billions Years from Today

Yoichiro Nambu Symposium (April 21, 2005) Paul Langacker (Penn) Neutrinos Implications/questions Second extreme example: time varying couplings and parameters Second extreme example: time varying couplings and parameters

Key constituent of the Universe • Why are the masses so small? • – Planck/GUT scale? e.g., seesaw or generalization, m m2 /M ν ∼ D N Are the neutrinos Dirac or • Majorana? – Neutrinoless double beta decay (ββ0ν) (inverted or degenerate spectr(Murphya) et al, astro-ph/0209488) (Murphy et al, astro-ph/0209488)

TASI (June 5, 2003) Paul Langacker (Penn) Yoichiro Nambu Symposium (April 21, 2005) Paul Langacker (Penn)

TASI (June 5, 2003) Paul Langacker (Penn) Neutrinos Implications/questions What is the dark matter? • !40 10 – Lightest neutralino in Key constituent of the Universe supersymmetry (if R parity • !41 10 conserved)? Axion? Why are the masses so small? – Direct searches: LHC, ILC; ] (normalised to nucleon) • 2 cold dark matter searches; high !42 – 10Planck/GUT scale? e.g., seesaenerw gy annihilation ν’s

section [cm 2 ! or generalization, mν mD/–MAxionN searches (resonant !43

Cross ∼ 10 1 2 cavities) 10 10 Are theWIMP Massneutr [GeV] inos Dirac– Groavir tation lensing (SNAP), • Majorana? CMB (Planck) What is the dark energy? – Neutrinoless double beta• decay (ββ0ν) (inverted or degen–erateVacuum energy (cosmological constant); spectra) time varying ﬁeld (quintessence)? – High precision supernova survey (SNAP); CMB (Planck)

Yoichiro Nambu Symposium (April 21, 2005) NYS APS (October 15, 2004) Paul Langacker (Penn) Paul Langacker (Penn) Neutrinos Implications/questions Why is there matter and not • antimatter?

10 – n /n 10− , n ¯ 0 Key cBonstituentγ ∼ of the UniverseB ∼ • – Electroweak baryogenesis? WhyLeptogenesiare the mass?sesDsoecasmally of? heavy • ﬁelds? CP T violation? – Planck/GUT scale? e.g., seesaw Theor generalivery bzegiation,nningm(inﬂatmi2on)/M • ν ∼ D N v – CMB (Planck); gravity waves Wall

Are the neutrinos Dirac or unbroken phase • (LISA) broken phase Majorana? q ! = 0 q q q becomes our world

– Neutrinoless double beta decay CP Sph ~_ 0 CP " B + L _ _ q q (ββ0ν) (inverted or degenerate_ _ q q Sph >> H spectra) " B + L

Yoichiro Nambu Symposium (April 21, 2005) Paul Langacker (Penn)

NYS APS (October 15, 2004) Paul Langacker (Penn) Why is there matter and not • antimatter?

10 – n /n 10− , n ¯ 0 B γ ∼ B ∼ – Electroweak baryogenesis? Leptogenesis? Decay of heavy ﬁelds? CP T violation? The very beginning (inﬂation) • Neutrinos Implications/questions – Relation to particle physics, strings, Λ?

– CMB (Planck); gravity waves (LISA) Key constituent of the Universe • Why are the masses so small? • – Planck/GUT scale? e.g., seesaw or generalization, m m2 /M ν ∼ D N Are the neutrinos Dirac or •NYS APS (October 15, 2004) Paul Langacker (Penn) Majorana? – Neutrinoless double beta decay (ββ0ν) (inverted or degenerate spectra)

Yoichiro Nambu Symposium (April 21, 2005) Paul Langacker (Penn) Neutrinos Implications/questions Conclusions

Key constituent of the Universe • The standard model is the correct description of nature down to • 16 1 10− cm Why a∼re the masses∼ 1soTeVsmall? • Standard model is complicated must be new physics – Pl•anck/GUT scale? e.g., seesa→w 2 or generalization, mν m /MN Precision tests severely∼ constrainD new TeV-scale physics • Are the neutrinos Dirac or • Promising theoretical ideas at Planck scale Majo•rana? Promising experimental program at colliders, accelerators, low – Ne•utrinoless double beta decay energy, cosmology (ββ0ν) (inverted or degenerate spectra) Challenge to make contact between theory and experiment •

Yoichiro NamYoichiburoSympNambuosiumSymp(Aprilosium (April21, 2005)21, 2005) PPaulaulLangacLangackker (P(Penn)enn)