Higgs@LHC: a Paradoxical Triumph the Higgs Is Related to Some of the Deepest Problems of HEP

Beyond the Standard Model CERN summer student lectures 2016

Lecture 1/ 4

Ch!"ope Grojean DESY (Hamburg) ICREA@IFAE (Barcelona) ( christophe.grojean@cern.ch ) What is physics beyond the Standard Model?

I don’t know. Nobody knows If it were known,? it would be part of the SM! You won’t learn during these lectures what is BSM (maybe) you’ll learn what BSM could be “Looking and not finding is different than not looking” we’ll study the limitations/defaults of the SM as a guide towards BSM we want to learn from our failures Christophe Grojean BSM 2 CERN, July 2016 Summary • many multi-boson measurements in Run-1 The• large SM number and... of thedi-boson LHC measurements data so far • evidence forrules VBS the W± Wworld!±jj and tri-boson Wyy [and we, HEP practitioners, are all entitled for some royalties!] • eagerly awaiting Run-2 data StandardModelPublicResults

multi-V measurements: 5 orders of magnitude the same set of eqs. describe phenomena overgood 15 agreement orders of magnitude with SM

Christophe02.09.2015 Grojean ATLAS Run-1 Mini Review: multi-VBSM measurements;3 MBI 2015 DESY CERN, July 201617 The SM and... the rest of the Universe

is not enough [and we all have to return our royalties!] neutrino masses +... matter-antimatter aymmetry Dark Matter Dark Energy { Quantum gravity

Planck Collaboration: Cosmological parameters

Christophe Grojean BSM 4 CERN, July 2016 Fig. 1. Planck foreground-subtracted temperature power spectrum (with foreground and other “nuisance” parameters fixed to their best-fit values for the base ⇤CDM model). The power spectrum at low multipoles (` = 2–49, plotted on a logarithmic multipole scale) is determined by the Commander algorithm applied to the Planck maps in the frequency range 30–353 GHz over 91% of the sky. This is used to construct a low-multipole temperature likelihood using a Blackwell-Rao estimator, as described in Planck Collaboration XV (2013). The asymmetric error bars show 68% confidence limits and include the contribution from uncertainties in foreground subtraction. At multipoles 50 ` 2500 (plotted on a linear multipole scale) we show the best-fit CMB spectrum computed from the CamSpec likelihood (see Planck  Collaboration XV 2013) after removal of unresolved foreground components. The light grey points show the power spectrum multipole-by-multipole. The blue points show averages in bands of width ` 31 together with 1 errors computed from the diagonal components of the band-averaged covariance matrix (which includes contributions⇡ from beam and foreground uncertainties). The red line shows the temperature spectrum for the best-fit base ⇤CDM cosmology. The lower panel shows the power spectrum residuals with respect to this theoretical model. The green lines show the 1 errors on the individual power spectrum estimates at high multipoles computed from the CamSpec covariance matrix. Note the change± in vertical scale in the lower panel at ` = 50.

3 Outline

Monday I general introduction, units Higgs physics as a door to BSM Monday II Naturalness Supersymmetry Grand unification, proton decay Tuesday Composite Higgs Extra dimensions Effective field theory Wednesday Cosmological relaxation Quantum gravity

Christophe Grojean BSM 5 CERN, July 2016 Ask questions

Your work, as students, is to question all what you are listening during the lectures...

Christophe Grojean BSM 6 CERN, July 2016 Recommended Readings

popular account “The Zeptospace odyssey” by Gian-Francesco Giudice CERN library link fun physics “Order-of-magnitude physics” by S. Mahajan, S. Phinney and P. Goldreich available for free online technical accounts “Journeys beyond the Standard Model” by P. Ramond CERN library link Many lecture notes, e.g. TASI (@Inspire: “t TASI”)

Christophe Grojean BSM 7 CERN, July 2016 Classical/Quantum EM & Antimatter an electron makes an electric field which carries an energy 1 e2 ECoulomb(r)= 4⇡✏0 r and interacts back to the electron and contributes to its mass mc2 = E 2 e ~c 13 i.e. E< 5 MeV mre 2 10 m ⌘ 4⇡✏0mec ⇠ re ⇠ At shortest distances or larger energies, classical EM breaks down

Physics beyond the standard model and dark matter 301 300 H. Murayama Quantum EM 1 e2 1 e2 E = E = 4⇡✏0 r 4⇡✏0 r

Fig. 2. The Coulomb self-energy of the electron. Fig. 4. Another contribution to the electron self-energy due to the ﬂuctuation of the vacuum. 3↵ 2 ~ E = mec log Weisskopf ‘39 4⇡ rmec 6 21 new states ≈ softer high-energyCoulomb (UV)s elf-enerbehavior:gy exactly:m<0.1me E<10 GeV 2 Christophe Grojean BSM 1 e 8 CERN, July 2016 !Epair . (2.5) = −4πε0 re

Fig. 3. The bubble diagram which shows the fluctuationAfterof the vtacuum.he linearly divergent piece 1/re is canceled, the leading contribution in the re 0 limit is given by → The resolution to this problem came from the discovery of the anti-particle of 3α 2 ! !E !ECoulomb !Epair mec log . (2.6) the electron, the positron, or in other words by doubling the degrees= of freedom+ = 4π mecre in the theory. The Coulomb self-energy discussed above canTherebe adepictedre two importantby a dia- things to be said about this formula. First, the correction gram Fig. 2 where the electron emits the Coulomb field (!aEvirtualis proportionalphoton) whichto the electron mass and hence the total mass is proportional is absorbed later by the electron (the electron “feels” its own Coulomb field).5 to the “bare” mass of the electron, But now that we know that the positron exists (thanks to Anderson back in 1932), and we also know that the world is quantum mechanical, one should2 think about2 3α ! the fluctuation of the “vacuum” where the vacuum produces(ma pairec )oobfsan e(lectronmec )bare 1 log . (2.7) = + 4π mecre and a positron out of nothing together with a photon, within the time allowed by ! " 2 the energy-time uncertainty principle !t !/!E !/(Therefore,2mec ) (Fig.we3).areThistalkingis about the “percentage” of the correction, rather than a new phenomenon which didn’t exist in the∼ classical∼electrodynamics,a huge additivande constant.modi- Second, the correction depends only logarithmically 2 13 fies physics below the distance scale d c!t !c/(2monec the) “2size”00 1of0−thecemlectron.. As a result, the correction is only a 9% increase ∼ ∼ = × Therefore, the classical electrodynamics actually did hainvethea finitemassapplicabilityeven for an electron as small as the Planck distance re 1/MPl 13 33 = = only down to this distance scale, much earlier than 2.8 1.160− 10cm− ascmexhibited. by the problem of the fine cancellation above. Given this×vacuumThe× factfluctuationthat the correctionpro- is proportional to the “bare” mass is a consequence cess, one should also consider a process where the electronof asittingnew symmetryin the vacuumpresent in the theory with the antiparticle (the positron): the by chance annihilates with the positron and the photon inchiralthe vacuumsymmetryfluctuation,. In the limit of the exact chiral symmetry, the electron is mass- and the electron which used to be a part of the fluctuationlessremainsand theinsteadsymmetryas a protects the electron from acquiring a mass from self- real electron (Fig. 4). V. Weisskopf [10] calculated this enercontribgyucorrections.tion to the elec-The finite mass of the electron breaks the chiral symmetry tron self-energy, and found that it is negative and cancelsetxplicitlyhe leading, andpiecebecausein thethe self-energy correction should vanish in the chiral sym- metric limit (zero mass electron), the correction is proportional to the electron 5The diagrams Figs. 2, 4 are not Feynman diagrams, but diagrams mass.in the old-fTherefore,ashioned perturba-the doubling of the degrees of freedom and the cancellation tion theory with different T -orderings shown as separate diagrams. The Feynman diagram for the self-energy is the same as Fig. 2, but represents the sum of Figs. 2, 4 and h6enceAn earlierthe linearpaperdivbyergWenceeisskopf actually found two contributions to add up. After Furry pointed is already cancelled within it. That is why we normally do not hear/readout a saboutign mlinearlyistake, hdie vpublishedergent an errata with no linear divergence. I thank Howie Haber for letting self-energy diagrams in the context of field theory. me know. New neutral leptons: motivations

Left-right symmetry

Quantisation of electric charges without Grand Uniﬁcation,asa consequence of requirement of anomalies cancellations The Standard Model: Matter how many quarks and leptons?Natural completion of the Standard Model in neutrino sector

=$&006>0,0&%(3),.6 =$&006>0,0&%(3),.6 )86?%((0&6@A0&'3),.B6."3,6C )86?%((0&6@A0&'3),.B6."3,6C E EE EEE E EE EEE '%..: !"#$%&' ("!)$*&' ()+"!$*&'$ 46 '%..: !"#$%&' ("!)$*&' ()+"!$*&'$ 46 #$%&/0: ! ! ! 4 #$%&/0: ! ! ! 4 ! t " t # t ( ! t " t # t ( Left Righ Left Righ Left Righ Left Righ ,%'0: Left !" Righ #$%&' ()" /2!), ,%'0: Left !" Righ #$%&' ()" /2!),

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$ /("!$*&' * 5FG6>0H6 0(-$1&' 0*&' 0*&' /("!$*&' * 5FG6>0H6 4 4 # 4 $ 4 4 4 4 # 4 $ 4 4 t " t ! t ! t " t ! t ! ! ) 4 - ! . . . ) 4 - '!), (%! * '!), + (%! , 020#(&),Lef Lef ,0!(&3,)Lef +0%7 #$%%& 020#(&),Lef Lef ,0!(&3,)Lef +0%7 #$%%& ,0!(&3,) ,0!(&3,) 8)� '(&() ,0!(&3,) ,0!(&3,) 8)� '(&()

-".(($%&' (-.")$%&' (")))$*&' ,-"#$*&' ."3,64 -".(($%&' (-.")$%&' (")))$*&' ,-"#$*&' ."3,64

@ particle fever] , , -5 -5 -5 9 5 -5 -5 -5 9 5 ' t # t $ t + ' t # t $ t + Left Righ Left Righ Left Righ Left Righ Left Righ Left Righ <0"(),. <0"(),.

D).),.6@A)�.B6."3,65 +0%7 D).),.6@A)�.B6."3,65 +0%7 020#(&), '!), (%! 8)� 020#(&), '!), (%! 8)� [pictures: courtesy[pictures: of D.E. Kaplan

an easy question... a not so simple answer! –p.21

Christophe Grojean BSM 9 CERN, July 2016 3

Gold"one equivalence 'eorem ➲ ➲ ➲

Christophe Grojean Higgs Physics 13 Ibarra, March. 10-12, 2o15 New neutral leptons: motivations

Left-right symmetry

=$&006>0,0&%(3),.6 =$&006>0,0&%(3),.6 )86?%((0&6@A0&'3),.B6."3,6C )86?%((0&6@A0&'3),.B6."3,6C E EE EEE E EE EEE '%..: !"#$%&' ("!)$*&' ()+"!$*&'$ 46 '%..: !"#$%&' ("!)$*&' ()+"!$*&'$ 46 #$%&/0: ! ! ! 4 #$%&/0: ! ! ! 4 6+6=12? ! t " t # t ( ! t " t # t ( Left Righ Left Righ Left Righ Left Righ ,%'0: Left !" Righ #$%&' ()" /2!), ,%'0: Left !" Righ #$%&' ()" /2!),

#",$%&' (-#$%&' #"!$*&' 4 #",$%&' (-#$%&' #"!$*&' 4 -" -" -" 4 -" -" -" 4 6x3+6=24? $ t % t & t % $ t % t & t % ;!%&7. ;!%&7. Left Righ Left Righ Left *)+, Righ Left .(&%,/0 Righ 1)(()' "$)(), Left *)+, Righ Left .(&%,/0 Righ 1)(()' "$)(), shouldn’t we count different color states? $ /("!$*&' * 5FG6>0H6 0(-$1&' 0*&' 0*&' /("!$*&' * 5FG6>0H6 4 4 # 4 $ 4 4 4 4 # 4 $ 4 4 t " t ! t ! t " t ! t ! ! ) 4 - ! . . . ) 4 - '!), (%! * '!), + (%! , 020#(&),Lef Lef Lef +0%7 #$%%& 020#(&),Lef Lef Lef +0%7 #$%%& R for QED ,0!(&3,) ,0!(&3,) ,0!(&3,) ,0!(&3,) L~e ,0!(&3,) 8)� '(&() ,0!(&3,) 8)� '(&() R 6x3x2+3x2+3=45?L≠e -".(($%&' (-.")$%&' (")))$*&' ,-"#$*&' ."3,64 -".(($%&' (-.")$%&' (")))$*&' ,-"#$*&' ."3,64 , , it is an accident that e -5 -5 -5 9 5 -5 -5 -5 9 5 SM is a chiral theory: e ' t # t $ t + ' t # t $ t + Left Righ Left Righ Left Righ Left Righ Left Righ Left Righ <0"(),. <0"(),. ? D).),.6@A)�.B6."3,65 +0%7 D).),.6@A)�.B6."3,65 +0%7 R 020#(&), '!), (%! 8)� 020#(&), '!), (%! 8)� 6x3x2+6x2=48?are there !

are they part of the SM?

an easy question... a not so simple answer! –p.21

Christophe Grojean BSM 9 CERN, July 2016 The Standard Model: Interactions

light U(1)Y electromagnetic interactions atoms 10-5 Photon γ molecules {β decay SU(2)L weak interactions W ± -2 n p + e +¯e 10 ⇥ 0 ± 0 + Z + bosons W , Z e + e D + D ⇥ (cs¯) (¯cs)

{ atomic nuclei SU(3)c strong interactions α decay 238U 234Th + 4He gluons ga 92 ⇥ 90 2 { strength Christophe Grojean BSM 10 CERN, July 2016 The Standard Model

the strong, weak and electromagnetic interactions of the elementary particles are described by gauge interactions

SU(3)CxSU(2)LxU(1)Y

- - ν! e → ν! e e- e-

ν! ν!

Fig. 14: First νµe elastic scattering event observed by the Gargamelle[Gargamelle Collaboration [10]collaboration, at CERN. Muon ’73] neutrinos enter the

Freon (CF3Br) bubble chamber from the right. A recoiling electron appears near the center of the image and travels toward the left, initiating a showerChristophe of curling Grojean branches. BSM 11 CERN, July 2016

By analogy with the calculation of the W -boson total width (2.43), we easily compute that

G M 3 Γ(Z νν¯)= F Z , → 12π√2 + 2 2 Γ(Z e e−)=Γ(Z νν¯) L + R . (2.47) → → e e ! " The neutral weak current mediates a reaction that did not arise in the V A theory, ν e ν e, − µ → µ which proceeds entirely by Z-boson exchange:

νµ e

This was, in fact, the reaction in which the ﬁrst evidence for the weak neutral current was seen by the Gargamelle collaboration in 1973 [10] (see Figure 14). To exercise your calculational muscles, please do

Problem 3 It’s an easy exercise to compute all the cross sections for neutrino-electron elastic scattering. Show that G2 m E σ(ν e ν e)= F e ν L2 + R2/3 , µ → µ 2π e e G2 m E ! " σ(¯ν e ν¯ e)= F e ν L2/3+R2 , µ → µ 2π e e G2 m E ! " σ(ν e ν e)= F e ν (L +2)2 + R2/3 , e → e 2π e e G2 m E ! " σ(¯ν e ν¯ e)= F e ν (L +2)2/3+R2 . (2.48) e → e 2π e e ! " 19 Gauge Theory as a Dynamical Principle

the strong, weak and electromagnetic interactions of the elementary particles are described by gauge interactions

SU(3)CxSU(2)LxU(1)Y

e+e- → W+W- e+ W+ ν W - e-

e+ Z, γ W+

e- W -

Christophe Grojean BSM 12 CERN, July 2016 The Standard Model and the Mass Problem

the strong, weak and electromagnetic interactions of the elementary particles are described by gauge interactions

SU(3)CxSU(2)LxU(1)Y

the masses of the quarks, leptons and gauge bosons don’t obey the full gauge invariance

is a doublet of SU(2)L but me me e ⇥

a mass term for the gauge field isn’t a a abc b c A = ⇤µ⇥ + gf A ⇥ invariant under gauge transformation µ µ

spontaneous breaking of gauge symmetry

Christophe Grojean BSM 13 CERN, July 2016 Electroweak Unification High energy (~ 100 GeV)

ZEUS ) 2

10 Low energy ZEUS (prel.) e+p NC 99-00 (pb/GeV 2 ZEUS ep NC 98-99 1 + /dQ SM e p NC (CTEQ6D)

d -1 SM ep NC (CTEQ6D) 10 This room is full of photons -2 but no W/Z 10 EM -3 10 The symmetry between W, Z and γ

-4 is broken at large distances 10 ZEUS e+p CC 99-00 -5 ZEUS ep CC 98-99 Weak 10 SM e+p CC (CTEQ6D) -6 SM e p CC (CTEQ6D) EM forces ≈ long ranges 10

-7 10 3 4 10 10 Weak forces ≈ short range Q2 (GeV2) 17 m < 6 10 eV m = 80.425 0.038 GeV W ± ± m 0 = 91.1876 0.0021 GeV Z ±

Christophe Grojean BSM 14 CERN, July 2016 The longitudinal polarization of massive W, Z c! c! c!

a massless particle is never at rest: always possible to distinguish (and eliminate!) the longitudinal polarization

v! 0!

the longitudinal polarization is physical for a massive spin-1 particle

(pictures: courtesy of G. Giudice) symmetry breaking: new phase with more degrees of freedom p⌃ E p⌃ = | | , polarization vector grows with the energy M M p⌃ | |⇥ Christophe Grojean BSM 15 CERN, July 2016 The longitudinal polarization of massive W, Z c! c! c!

a massless particle is never at rest: always possible to distinguish (and eliminate!) the longitudinal polarization

Guralnik et al ’64 v! 3=2+1 0!

the longitudinal polarization is physical for a massive spin-1 particle

b 2 2 2 2 2 g mt (mt mW ) at threshold (mt ~ mW) (t bWL)= 2 3 t ! 64⇡ mW mt democratic decay g2 2(m2 m2 )2 t W at high energy (m >> mW) (t bWT )= 3 t ! 64⇡ mt WL dominates the decay W+

At high energy, the dominant degrees of freedom are WL

Christophe Grojean BSM 16 CERN, July 2016 The BEH mechanism: “VL=Goldstone bosons” At high energy, the physics of the gauge bosons becomes simple

b ~~ why you should be2 stunned2 2 by2 this2 result: ~~ g mt (mt mW ) at threshold (mt ~ mW) (t bWL)= 2 3 t ! 64⇡ m m democratic decay daughter we expect:W t 2 2 2 2 2 (dimensionalg analysis)2(mt mW) g mmother (t bW )= at high energy (mt >> mW) mother T 3 ! 64⇡ mt ⇠ + 3 WL dominateslike thethe decayHiggs g W instead m means g m / mother / couplings! At high energy, the dominant degrees of freedom are WL daughter very efficient way to suck up energy from the mother particle

⌧ ⌧naive Goldstone equivalence theorem ⌧ ± W L, ZL ≈ SO(4)/SO(3) LEP already established the BEH mechanism The pending question was: how is it realized? Via a fundamental EW doublet? A la technicolor? Is there a Higgs boson in addition to the 3 Goldstone bosons?

In other words, LEP established a simple description of the electroweak sector for E >> mW.

8⇡mW This description is valid for mW E 4⇡v = ⌧ ⌧ g The goal of the LHC was/is to understand what comes next

Christophe Grojean BSM 16 CERN, July 2016 Call for extra degrees of freedom

NO LOSE THEOREM WL WL Bad high-energy behavior for kµ p the scattering of the longitudinal polarizations µ ⇥ 2 ⇤ ⌅ = (k) (l)g (2⇥µ⇤⇥⇥⌅ ⇥µ⇥ ⇥⇤⌅ ⇥µ⌅⇥⇥⇤) (p) (q) A l q 4 WL WL 2 E = g 4 A 4MW

violations of perturbative unitarity around E ~ M/√g (actually M/g)

Extra degrees of freedom are needed to have a good description

of the W and Z masses at higher energies numerically: E ~ 3 TeV the LHC was sure to discover something!

Christophe Grojean BSM 17 CERN, July 2016 MW/√(g/4π)~500GeV or MW/(g/4π)~3TeV?

Lewellyn Smith ‘73 Dicus, Mathur ‘73 Cornwall, Levin, Tiktopoulos ’73 exerciseW+ W+ E 4 = g2 A M ✓ W ◆

W- W- + W+ W+ + http://cp3wks05.fynu.ucl.ac.be/twiki/bin/view/Physics/Cargese W+ W+

γ, Z0 4 2 E γ, Z0 = g A M ✓ W ◆ W- W- W- W-

E 2 impossible to further cancel the amplitude = g2 A M without introducing new degrees of freedom ✓ W ◆

Christophe Grojean BSM 18 CERN, July 2016

Cargese 2010 Fabio Maltoni What is the SM Higgs? A single scalar degree of freedom that couples to the mass of the particles h h2 h = m2 W +W + 1+2a + b m ¯ 1+c LEWSB W µ µ v v2 L R v ✓ ◆ ✓ ◆ ‘a’, ‘b’ and ‘c’ are arbitrary free couplings - - W W growth cancelled for 2 2 1 a s a = 1 = s A v2 s m2 restoration of h h ⇥ perturbative unitarity W+ W+

Christophe Grojean BSM 19 CERN, July 2016 !µ! = 1 kµ! = 0 µ − µ !µ! = 1 kµ! = 0 µ − µ

µ µ µ ! !µ = 1 kik!µµx = 0 Aµ −= !µ e µ ikµx Aµ = !µ e

µ ikµx Aµ = !µ e µ k E kµ E ! = ( M , 0, 0, M ) M + ( M ) ⊥ ≈ O µ k E kµ E ! = ( M , 0, 0, M ) M + ( M ) ⊥ ≈ O µ k E kµ E ! = ( M , 0, 0, M ) M + ( M ) ⊥ µ ≈ O !1 = (0, 1, 0, 0) µ !µ2 = (0, 0, 1, 0) ! !1 = (0, 1, 0, 0) µµ !!21 == ((00,,10,,01,,00)) ! µ !2 = (0, 0, 1, 0) k !kµ = E2 k2 = M 2 µ − µ 2 2 2 kµk = E k = M k kµ = E2 −k2 = M 2 µ − kµ = (E, 0, 0, k) µ kkµ == (EE,,00,,00,,kk)) What is the SM Higgs? A A + ∂ ! µ → µ µ W+ W+ AAµµ AAµµ++∂∂µµ!! W+ W+ W+ W+ →→

0 2 γ, Z 2 E γ, Z0 = g 2 A 2 MEW 2 - - - - = g2 " E # W W W W A= g MW + W- W- A " MW# " # W+ W+ +2 W+ W+ 2 E = g E 2 A − 2 M 2 = g EW h0 A − 2 "MW # 0 = g " # h A − M " W # W- W- 2 MH 2 - - 2 M W W == g2 H A 22MMW 2 A " MWH # The Higgs boson unitarizes the W scattering = g2 " # (if its mass is below ~ 1 TeV) A 2MW Lee, Quigg," Thacker ’77#

Christophe Grojean BSM 20 CERN, July 2016

3344

34 What is the Higgs the name of? A single scalar degree of freedom that couples to the mass of the particles h h2 h = m2 W +W + 1+2a + b m ¯ 1+c LEWSB W µ µ v v2 L R v ✓ ◆ ✓ ◆ ‘a’, ‘b’ and ‘c’ are arbitrary free couplings

For a=1: perturbative unitarity in elastic channels WW → WW

For b = a2: perturbative unitarity in inelastic channels WW → hh

Cornwall, Levin, Tiktopoulos ’73 Contino, Grojean, Moretti, Piccinini, Rattazzi ’10

b a

Christophe Grojean BSM 21 CERN, July 2016 What is the Higgs the name of? A single scalar degree of freedom that couples to the mass of the particles h h2 h = m2 W +W + 1+2a + b m ¯ 1+c LEWSB W µ µ v v2 L R v ✓ ◆ ✓ ◆ ‘a’, ‘b’ and ‘c’ are arbitrary free couplings

For a=1: perturbative unitarity in elastic channels WW → WW

For b = a2: perturbative unitarity in inelastic channels WW → hh

For ac=1: perturbative unitarity in inelastic WW → ψ ψ

Cornwall, Levin, Tiktopoulos ’73 Contino, Grojean, Moretti, Piccinini, Rattazzi ’10

a c

Christophe Grojean BSM 21 CERN, July 2016 What is the Higgs the name of? A single scalar degree of freedom that couples to the mass of the particlesHiggs “It has to do with htheh 2EWSB” h = m2 W +W + 1+2a + b “Itm ¯looks 1+ likec a doublet” LEWSB W µ µ v v2 Related L toR EWSBv overall compatible w/ SM ✓ ◆ ✓ ◆ ‘a’, ‘b’ and ‘c’ are arbitrary freeCMS Preliminarycouplingss = 7 TeV, L 5.1 fb-1 s = 8 TeV, L 19.6 fb-1 CMS Preliminary s = 7 TeV, L 5.1 fb-1 s = 8 TeV, L 19.6 fb-1 f

Already first data gave evidence of: 1/2 SM Higgs Fermiophobic Bkg. only

68% CL For a=1: perturbative2 unitarity in elastic channels WW → WW 2 H m gVVh m t 2 V 95% CL WW , V 1 / vFor b = a2:⌘ perturbative2v / v2 unitarity in inelastic channels WW → hhZ 95% C.L. W H

or (g/2v)

1 For ac=1: perturbative unitaritycoupling in inelastic WW → ψ ψ H ZZ H bb True in the SM: -1 10 0 Cornwall, Levin, Tiktopoulos ’73 Contino, Grojean,b Moretti, Piccinini, Rattazzi ’10 H m mV = , V = v v -2 -1 10“It Higgshas couplings to do SM with the EWSB” Scaling coupling ∝ mass follows naturally if the new boson is part of the sector that are proportional -2 1 2 3 4 5 10 20 100 200 0 0.5 1 1.5 -1 -1 breaks the EW symmetry to the masses ofa the masscparticles (GeV) CMS Preliminary s = 7 TeV, L 5.1 fb s = 8 TeV,V L 19.6 fb

Already first data gave evidence of: 1/2

68% CL It does not necessarily imply that the new 2 m 2 gVVh mV 95% CL t boson is part of an SU(2)L doubletCMS PAS-HIG-14-009 Ex: composite, NG boson in TC 1 10 V 2 / v ⌘ 2v / v W Z or (g/2v)

SM coupling ChristopheFor aGrojean non-doublet BSM 21 CERN, July 2016 = O(1) one naively expects: SM True in the SM: 10-1 3 b m mV = , V = v v -2 10 SM

Scaling coupling ∝ mass follows naturally if the new boson is part of the sector that 1 2 3 4 5 10 20 100 200 breaks the EW symmetry mass (GeV) It does not necessarily imply that the new boson is part of an SU(2)L doublet Ex: composite NG boson in TC

For a non-doublet SM = O(1) one naively expects: SM 3 Higgs boson at the LHC producing a Higgs boson is a rare phenomenon since its interactions with particles are proportional to masses and ordinary matter is made of light elementary particles NB: the proton is not an elementary particle, its mass doesn’t measure its interaction with the Higgs substance

From electrons From top quarks e e t t

h h

probability ~ 1 probability ~ 10-11 but no top quark at our disposal

Christophe Grojean BSM 22 CERN, July 2016 8 OCTOBER 2013

Higgs boson at the LHC

Difficult task Homer Simpson’s principle of life: If something’s hard to do, is it worth doing?

Homer Simpson has a famous quote:

If something’s hard to do, then it’s not worth doing.

Christophe Grojean BSM 23 CERN, July 2016 My version: Scienti!c Background on the Nobel Prize in Physics "#$% If something’s hard to measure, then it’s worth measuring at a 100 TeV collider! THE BEH-MECHANISM, INTERACTIONS WITH SHORT RANGE FORCES AND SCALAR PARTICLES

Compiled by the Class for Physics of the Royal Swedish Academy of Sciences

THE ROYAL SWEDISH ACADEMY OF SCIENCES has as its aim to promote the sciences and strengthen their inﬂuence in society.

BOX 50005 !LILLA FRESCATIVÄGEN 4 A", SE#104 05 STOCKHOLM, SWEDEN Nobel Prize® and the Nobel Prize® medal design mark TEL +46 8 673 95 00, [email protected] HTTP://KVA.SE are registrated trademarks of the Nobel Foundation Higgs boson at the LHC

t t t H

Christophe Grojean BSM 24 CERN, July 2016 Higgs boson at the LHC

σ ~ 10 pb ⇔ 105 events for L=10 fb-1 Higgs production Higgs decay

t t t H

The LHC has produced 105 Higgs bosons out of 1016 pp collisions

Christophe Grojean BSM 24 CERN, July 2016 4. SM Higgs production at the LHCSM Higgs @ LHC Physics at the LHC: some generalities The production of a Higgs is wiped out by QCD background √s=7+7=14 TeV √seﬀ √s/3 5 TeV LHC: pp collider − ⇒ ∼ ∼ 10 fb 1 ﬁrst years and 100 fb−1 later L∼ _ pp/pp cross sections 10 15 _ only 1 out of 100 billions events

Huge cross sections for QCD processes. (fb) pp pp 10 14 σ σ • tot Small cross sections for EW Higgs signal. 10 13 are “interesting” LHC

12 LHC8 • 10 LHC14 (for comparison, Shakespeare’s 43 works

10 Tevatron

11 Tevatron S/B > 10 a needle in a haystack! 10 contain only 884,429 words in total) 10 σ _ ∼ ⇒ 10 bb Need some strong selection criteria: 9 10 furthermore many of the • 8 10 jet ¬ σ (E > √s/20) Trigger: get rid of uninteresting events... jet T 7 background events furiously look 10 σW σ 6 Z Select clean channels: H γγ, VV " 10 σ (Ejet > 100GeV) jet T like signal events → → 10 5

Use different kinematic features for Higgs 10 4

10 3 _ σtt Combine different decay/production channels ¬ 2 σ (Ejet > √s/4) ... like finding the paper you 10 jet T

σ (M =150GeV) 8 Have a precise knowledge of S and B rates. 10 Higgs H are looking for in (10 copies of) 1 σ (M =500GeV) Gigantic experimental (+theoretical) efforts! -1 Higgs H 10 John Ellis’ office 3 4 ¬ • 10 10 √s (GeV)

ISSCSMB ’08, Mugla, 10–18/09/08 Higgs Physics – A. Djouadi – p.20/47

Christophe Grojean BSM 25 CERN, July 2016 Higgs@LHC: a paradoxical triumph The Higgs is related to some of the deepest problems of HEP

2 2 = V µ H†H + H†H + y ⇤¯ ⇤ H + h.c. LHiggs 0 ij Li Rj ⇥ ⇥ vacuum energy hierarchy problem triviality/stability mass and mixing flavour & CP m 100 GeV M cosmological constant H ⇥ Pl of EW vacuum hierarchy 3 4 4 V (2 10 eV) M 0 ⇥ ⇤ PL ~~ Higgs interactions ~~ gauge symmetry is the organizing principle for interactions in the gauge sector not in the Higgs sector ➾ many free parameters! but they obey 3 basic structures 2 ghff mf g m (1) proportionality: / hV V / V ➠ test for extended Higgs sectors

(2) factor of proportionality: ghff /mf = p2/v ➠ test for extended Higgs sectors ➠ test for Higgs compositeness

(3) flavor alignment: ghfifj ij / ➠ test for flavor models, origin of fermion masses Christophe Grojean BSM 26 CERN, July 2016