aleandro nisati infn - roma scuola di fisica di otranto 19...

Physics Prospects at HL-LHC

Aleandro Nisati INFN - Roma

Scuola di fisica di Otranto 19 – 24 Settembre 2013

Present results by LHC •  LHC data sample: √s = 7 and 8 TeV; L ~ 5 , 20

fb-1 1.  Discovery of a Higgs boson with mass of

about 125 GeV 2.  NO evidence of signal of NEW PHYSICS

Beyond Standard Model, both from direct and indirect searches

•  Impressive success of Standard Model in describing the LHC data

•  Vedi lezioni di Tiziano Camporesi (Higgs boson physics) e di Giacomo Polesello (BSM)

2

Higgs boson

•  Distribution of the 4-lepton invariant mass obtained with the data recorded with the ATLAS detector

3

[GeV]4lm100 150 200 250

Even

ts/5

GeV

0

5

10

15

20

25

30

35

40

-1Ldt = 4.6 fb = 7 TeV s-1Ldt = 20.7 fb = 8 TeV s

4lZZ*HData 2011+ 2012SM Higgs Boson

=124.3 GeV (fit)H mBackground Z, ZZ*

tBackground Z+jets, tSyst.Unc.

ATLAS

Standard Model results

4

W Z WW Wt

[pb]

tota

lσ

1

10

210

310

410

510

-120 fb

-113 fb

-15.8 fb

-15.8 fb

-14.6 fb

-12.1 fb-14.6 fb

-14.6 fb-11.0 fb

-11.0 fb

-135 pb

-135 pb

tt t WZ ZZ

= 7 TeVsLHC pp Theory

)-1Data (L = 0.035 - 4.6 fb

= 8 TeVsLHC pp Theory

)-1Data (L = 5.8 - 20 fb

ATLAS PreliminaryATLAS PreliminaryATLAS Preliminary

Beyond Standard Model results

5

Even

ts

-210

-110

1

10

210

310

410

510

610

710Data 2012

*Z/tt

Dijet & W+JetsDibosonZ’(1500 GeV)Z’(2500 GeV)

PreliminaryATLAS ee SearchZ’

-1 L dt = 20 fb = 8 TeVs

[GeV]eem100 200 300 400 1000 2000 3000

Obs

erve

d / E

xpec

ted

0.60.8

11.21.4

Dielectron invariant mass (mee) distribution with statistical uncertainties after final selection, compared to the stacked sum of all expected backgrounds, with two selected Z′ signals overlaid. The SSM bin width is constant in log mee.

SUSY Searches

6 Mass scales [GeV]

0 200 400 600 800 1000 12000χ∼ l → l

~

0χ∼ 0

χ∼ν τττ → ±χ∼ 2

0χ∼

0χ∼ 0

χ∼ν τ ll→ ±χ∼ 2

0χ∼

0χ∼ 0

χ∼ W Z → 2

0χ∼ ±χ∼

0χ∼

0χ∼νν

-l+ l→ -χ∼+χ∼

0χ∼ 0

χ∼ν lll → ±χ∼ 2

0χ∼

0χ∼ bZ → b

~0χ∼ tW → b

~0χ∼ b → b

~

)0χ∼ W → ±χ∼ b (→ t~

)0χ∼ W→ +

χ∼ b(→ t~0χ∼ t → t~

0χ∼ t → t~

0χ∼ q → q~

0χ∼ q → q~

))0χ∼ W→ ±χ∼ t(→ b

~ b(→ g~

)0χ∼γ →

2

0χ∼ qq(→ g~

)0χ∼ W→

±χ∼|0

χ∼γ→2

0χ∼ qq(→ g~

)0χ∼ W→±χ∼ qq(→ g~

)0χ∼ Z →

2

0χ∼ qq (→ g~

)0χ∼ ν± l→ ±χ∼ qq(→ g~

)0χ∼ t→ t~ t(→ g~

)0χ∼ |0

χ∼ W→±χ∼ qq(→ g~)0

χ∼ |0χ∼ τ τ →

2

0χ∼ qq(→ g~

)0χ∼

-l+ l→2

0χ∼ qq (→ g~

0χ∼ tt → g~

0χ∼ bb → g~

0χ∼ qq → g~

0χ∼ qq → g~

SUS-13-006 L=19.5 /fb

SUS-13-008 SUS-13-013 L=19.5 /fb

SUS-13-011 L=19.5 /fb x = 0.25x = 0.50

x = 0.75

SUS-13-008 L=19.5 /fb

SUS-12-001 L=4.93 /fb

SUS-11-010 L=4.98 /fb

SUS-13-006 L=19.5 /fb x = 0.05x = 0.50

x = 0.95

SUS-13-006 L=19.5 /fb

SUS-13-012 SUS-12-028 L=19.5 11.7 /fb

SUS-12-005 SUS-11-024 L=4.7 /fb

SUS-12-028 L=11.7 /fb

SUS-13-008 SUS-13-013 L=19.5 /fb

SUS-13-007 SUS-13-008 SUS-13-013 L=19.4 19.5 /fbSUS-12-024 SUS-12-028 L=19.4 11.7 /fb

SUS-12-001 L=4.93 /fb

SUS-13-012 SUS-12-028 L=19.5 11.7 /fb

SUS-12-010 L=4.98 /fb x = 0.25x = 0.50

x = 0.75

SUS-12-005 SUS-11-024 L=4.7 /fb

SUS-13-008 SUS-13-013 L=19.5 /fb

SUS-13-013 L=19.5 /fb x = 0.20x = 0.50

SUS-12-004 L=4.98 /fb

SUS-13-006 L=19.5 /fb

SUS-11-011 L=4.98 /fb

SUS-13-011 L=19.5 /fb left-handed topunpolarized top

right-handed top

SUS-11-024 SUS-12-005 L=4.7 /fb

SUS-11-021 SUS-12-002 L=4.98 4.73 /fb x = 0.25x = 0.50

x = 0.75

SUS-13-006 L=19.5 /fb x = 0.05x = 0.50

x = 0.95

SUS-13-006 L=19.5 /fb

SUS-11-030 L=4.98 /fb

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Summary of CMS SUSY Results* in SMS framework

CMS Preliminary

m(mother)-m(LSP)=200 GeV m(LSP)=0 GeVEPSHEP 2013

= 7 TeVs = 8 TeVs

lspm⋅-(1-x)motherm⋅ = xintermediatemFor decays with intermediate mass,

Only a selection of available mass limits*Observed limits, theory uncertainties not included

Probe *up to* the quoted mass limit

Exotics Searches

7 Mass scale [TeV]-110 1 10 210

Oth

erEx

cit.

ferm

.N

ew

quar

ksLQ

V'C

IEx

tra d

imen

sion

s

Magnetic monopoles (DY prod.) : highly ionizing tracksMulti-charged particles (DY prod.) : highly ionizing tracks

jjmColor octet scalar : dijet resonance, llm), µµll)=1) : SS ee (→

L±± (DY prod., BR(HL

±±H Zlm (type III seesaw) : Z-l resonance, ±Heavy lepton NMajor. neutr. (LRSM, no mixing) : 2-lep + jets

WZmll), νTechni-hadrons (LSTC) : WZ resonance (l

µµee/mTechni-hadrons (LSTC) : dilepton, γl

m resonance, γExcited leptons : l- WtmExcited b quark : W-t resonance, jjmExcited quarks : dijet resonance, jetγ

m-jet resonance, γExcited quarks : qνlmVector-like quark : CC,

Ht+X→Vector-like quark : TT,missT

E SS dilepton + jets + →4th generation : b'b' WbWb→ generation : t't'th4

jjντjj, ττ=1) : kin. vars. in βScalar LQ pair (jjνµjj, µµ=1) : kin. vars. in βScalar LQ pair (jjν=1) : kin. vars. in eejj, eβScalar LQ pair (tb

m tb, LRSM) : → (RW'tqm=1) :

R tq, g→W' (

µT,e/mW' (SSM) : ttm l+jets, → tZ' (leptophobic topcolor) : t

ττmZ' (SSM) : µµee/mZ' (SSM) :

,missTEuutt CI : SS dilepton + jets + llm, µµqqll CI : ee &

)jj

m(χqqqq contact interaction : )jjm(

χQuantum black hole : dijet, F T

pΣ=3) : leptons + jets, DM /THMADD BH (ch. part.N=3) : SS dimuon, DM /THMADD BH ( tt

m l+jets, → t (BR=0.925) : tt t→KK

RS glljjmBulk RS : ZZ resonance, νlν,lTmRS1 : WW resonance, llmRS1 : dilepton, llm ED : dilepton, 2/Z1S

,missTEUED : diphoton + / llγγmLarge ED (ADD) : diphoton & dilepton,

,missTELarge ED (ADD) : monophoton + ,missTELarge ED (ADD) : monojet +

mass862 GeV , 7 TeV [1207.6411]-1=2.0 fbLmass (|q| = 4e)490 GeV , 7 TeV [1301.5272]-1=4.4 fbL

Scalar resonance mass1.86 TeV , 7 TeV [1210.1718]-1=4.8 fbL

)µµ mass (limit at 398 GeV for L±±H409 GeV , 7 TeV [1210.5070]-1=4.7 fbL

| = 0)τ

| = 0.063, |Vµ

| = 0.055, |Ve

mass (|V±N245 GeV , 8 TeV [ATLAS-CONF-2013-019]-1=5.8 fbL) = 2 TeV)

R(WmN mass (1.5 TeV , 7 TeV [1203.5420]-1=2.1 fbL

))Tρ(m) = 1.1

T(am, Wm) + Tπ(m) =

Tρ(m mass (

Tρ920 GeV , 8 TeV [ATLAS-CONF-2013-015]-1=13.0 fbL

)W

) = MTπ(m) - Tω/Tρ(m mass (Tω/T

ρ850 GeV , 7 TeV [1209.2535]-1=5.0 fbL

= m(l*))Λl* mass (2.2 TeV , 8 TeV [ATLAS-CONF-2012-146]-1=13.0 fbLb* mass (left-handed coupling)870 GeV , 7 TeV [1301.1583]-1=4.7 fbL

q* mass3.84 TeV , 8 TeV [ATLAS-CONF-2012-148]-1=13.0 fbL

q* mass2.46 TeV , 7 TeV [1112.3580]-1=2.1 fbL)Q/mν = qQκVLQ mass (charge -1/3, coupling 1.12 TeV , 7 TeV [ATLAS-CONF-2012-137]-1=4.6 fbL

T mass (isospin doublet)790 GeV , 8 TeV [ATLAS-CONF-2013-018]-1=14.3 fbL

b' mass720 GeV , 8 TeV [ATLAS-CONF-2013-051]-1=14.3 fbL

t' mass656 GeV , 7 TeV [1210.5468]-1=4.7 fbL gen. LQ massrd3534 GeV , 7 TeV [1303.0526]-1=4.7 fbL

gen. LQ massnd2685 GeV , 7 TeV [1203.3172]-1=1.0 fbL

gen. LQ massst1660 GeV , 7 TeV [1112.4828]-1=1.0 fbL

W' mass1.84 TeV , 8 TeV [ATLAS-CONF-2013-050]-1=14.3 fbLW' mass430 GeV , 7 TeV [1209.6593]-1=4.7 fbL

W' mass2.55 TeV , 7 TeV [1209.4446]-1=4.7 fbL

Z' mass1.8 TeV , 8 TeV [ATLAS-CONF-2013-052]-1=14.3 fbL

Z' mass1.4 TeV , 7 TeV [1210.6604]-1=4.7 fbLZ' mass2.86 TeV , 8 TeV [ATLAS-CONF-2013-017]-1=20 fbL

(C=1)Λ3.3 TeV , 8 TeV [ATLAS-CONF-2013-051]-1=14.3 fbL

(constructive int.)Λ13.9 TeV , 7 TeV [1211.1150]-1=5.0 fbL

Λ7.6 TeV , 7 TeV [1210.1718]-1=4.8 fbL=6)δ (DM4.11 TeV , 7 TeV [1210.1718]-1=4.7 fbL

=6)δ (DM1.5 TeV , 7 TeV [1204.4646]-1=1.0 fbL

=6)δ (DM1.25 TeV , 7 TeV [1111.0080]-1=1.3 fbL

massKK

g2.07 TeV , 7 TeV [1305.2756]-1=4.7 fbL = 1.0)PlM/kGraviton mass (850 GeV , 8 TeV [ATLAS-CONF-2012-150]-1=7.2 fbL

= 0.1)PlM/kGraviton mass (1.23 TeV , 7 TeV [1208.2880]-1=4.7 fbL

= 0.1)PlM/kGraviton mass (2.47 TeV , 8 TeV [ATLAS-CONF-2013-017]-1=20 fbL

-1 ~ RKKM4.71 TeV , 7 TeV [1209.2535]-1=5.0 fbL

-1Compact. scale R1.40 TeV , 7 TeV [1209.0753]-1=4.8 fbL

=3, NLO)δ (HLZ SM4.18 TeV , 7 TeV [1211.1150]-1=4.7 fbL

=2)δ (DM1.93 TeV , 7 TeV [1209.4625]-1=4.6 fbL

=2)δ (DM4.37 TeV , 7 TeV [1210.4491]-1=4.7 fbL

Only a selection of the available mass limits on new states or phenomena shown*

-1 = ( 1 - 20) fbLdt∫ = 7, 8 TeVs

ATLASPreliminary

ATLAS Exotics Searches* - 95% CL Lower Limits (Status: May 2013)

The priorities for collider physics after July 4th

2012 •  The recently discovered new particle drives to a

number of fundamental open points that are top priority for the physics programme for the LHC and future energy frontier accelerators: 1.  Precision measurement of the mass of this new particle 2.  Determination of the quantum numbers spin and parity,

JP, and CP violation 3.  Measurement of couplings to elementary fermions and

bosons 4.  Measurement of the di-Higgs boson production 5.  Comparison of these physics properties with those

predicted by Standard Model 6.  Search for possible partners (neutral and/or charged) of

this boson 7.  Is this particle a fundamental object, or it is composite?

8

The priorities for collider physics after July 4th 2012

•  The investigations of the electroweak symmetry breaking cannot be limited to the study of the Higgs sector only: several points still to be addressed. Among these: – The dependence with energy of the Vector Boson

Scattering cross section dσ/dmVV (WW, WZ and ZZ)

– The hierarchy problem, that motivated new theories beyond SM, such as SUperSYmmetry, Extra-Dimensions, Technicolor models

9

The priorities for collider physics after July 4th •  This enriches the collider physics programme:

8.  Analyse the Vector Boson scattering cross section to study whether the cross-section regularization is operated by the Higgs boson (as predicted by SM) or by other processes associated to pyisics beyond SM;

9.  Naturalness problem: continue the search for SUSY particles, in particular search for third generation squarks: to be effective, the mass of the stop quark cannot be too different from the one of the top quark; also continue the search for gauginos and for 1st and 2nd generation squarks; similarly for Extra-Dimensions.

10. Continue the search for heavy resonances decaying to photon, lepton or quark pairs, and for deviations from SM of physics distributions highly sensitive to New Physcs (di-jet angular distribution,…) 10

The European Strategy for Particle Physics

•  These themes have been widely discussed in the context of the Symposium on the European Strategy for Particle Physics, held on September 10 to 12, 2012.

•  Many proposals have been submitted (collider energy frontier physics, heavy flavour physics, neutrino and astroparticle physics, etc. etc.)

11

The European Strategy for Particle Physics •  High Energy Frontier: Name beams collider

geometry √s, TeV luminosity Opera9on

(years)

HL-LHC pp circular 14 3000 fb-1 2024-2030 HE-LHC pp circular 26-33 100-300 fb-1/year After 2035

VHE-LHC pp circular 40-100 - After 2035 LEP3 e+e− circular 0.240 11034 cm-2s-1 After 2024 ILC e+e− linear 0.2501.0 ~11034 cm-2s-1 ~ 2030

CLIC e+e− linear 0.5003.0 2-61034 cm-2s-1 After 2030 TLEP e+e− circular 0.24-0.350 51034 cm-2s-1 After 2035 LHeC e−(e+)p circular O(100 fb-1) After 2022

γγ-collider γγ ? µ-collider µ+µ− circular ?

I’ll focus on examples of physics perspectives at the High Luminosity-LHC (HL-LHC) 12

Some proposals for future colliders

13

LEP3

TLEP/VHE-‐LHC CLIC

See also: arxiv:1302.3318

The LHC Upgrade plan

•  About 350 fb-1 are expected at the end of the LHC Programme –  300 fb-1 have been assumed as

baseline in the studies made by ATLAS and CMS

•  Experimental challenges •  The average number of proton-proton collisions per triggered events

is about 140 •  The trigger has to cope with the effects induced by the large pile-up •  The inner detector has to be fast and with high granularity and

redundancy, to cope with the effects from large occupancy •  The detector has to be (even more) radiation hard

14

LHC roadmap to achieve full potential

Pippa Wells, CERN June 2013 15

…

Run 1

Injector + LHC Phase I upgrade to ultimate design luminosity2018 LS2

2019

√s=14 TeV, L~2x1034cm-2s-1, bunch spacing 25ns2020

~75-100 fb-1

2015

2016

2012 ~25 fb-1

2013

2014

2017

LS1

~3000 fb-1

2021 ~350 fb-1

HL-LHC Phase II upgrade: Interaction Region, crab cavities?2022 LS3

2023

√s=14 TeV, L~5x1034cm-2s-1, luminosity levelling2030?

Go to design energy, nominal luminosity - Phase 0

√s=13~14 TeV, L~1x1034cm-2s-1, bunch spacing 25ns

2009 LHC startup, √s 900 GeV2010

√s=7+8 TeV, L~6x1033cm-2s-1, bunch spacing 50ns2011

What LHC will find during next run •  LHC physics programme: √s = ~ 13 TeV; L ~

300 fb-1

16

LHC after 300 fb-1

Will discover New Physics

No deviations from SM Direct evidence of NP production

Deviations from SM. An example: Higgs boson properties;

è Explore physics at the luminosity LHC upgrade è Study new accelerator facilities

Event pileup at the LHC •  Present ATLAS and CMS detectors

have been designed for <µ> ~ 23 pp interactions / bunch-crossing –  And continue to do an excellent job

with 35

•  But cannot handle (an average of) 140 events of pileup

Zàμμ decay in a large pileup event

Missing transverse energy resoluRon as a funcRon of the number of the reconstructed verRces

17

Detector Upgrade

18

•  In a nutshell – detector upgrades are planned so as to maintain or improve on the present performance as the instantaneous luminosity increases

•  A particular challenge is to refine the hardware (level-1) and software (high level) triggers to maintain sensitivity with many interactions per bunch crossing – “pileup”

•  Offline algorithms also need to be developed to maintain performance with pileup

•  Focus here on upgrades which change the performance. In addition, there is a continuous huge effort in consolidation, eg. new cooling systems, improved electronics and power supplies, shielding additions...

•  Phase 0/I upgrades are better defined than Phase II

CMS event with 78 pileup

Vedi talk di L. Rossi

Physics at HL-LHC •  On the basis of what discussed in the previous slides,

ATLAS and CMS presented two documents for the Symposium in Cracow, subsequently updated in October 2012 for the Briefing Book, and for the Snowmass meeting in 2013.

•  These documents focused on: –  Higgs couplings, confirm spin, CP and self-couplings –  Vector Boson Scattering –  SUSY –  Exotics –  SM: Vector Boson TGCs and top quark FCNC

•  Workshop ECFA HL-LHC Aix-les-Bains, October 1st-3rd

19

Approaches adopted for physics perspectives estimation

•  ATLAS: perform physics simulation with a fast procedure based on simple functions applied to physics objects (electrons, photons, muons, tau, jets, b-jets, missing transverse energy) to mimic the effects from energy (momentum) resolution; acceptance, identification and reconstruction efficiencies, b-tagging efficiencies, fake rates

•  CMS: the upgraded detector will compensate the effects from event pile-up; assume three different scenarios: –  Scenario 1: all systematic uncertainties are kept unchanged wrt

those in current data analyses –  Scenario 2: the theoretical uncertainties are scaled by a factor of

1/2, while other systematic uncertainties are scaled √L; –  Scenario 3: set theoretical uncertainties to zero, to demonstrate

their interplay with the experimental uncertainties; –  è The truth will be most likely somewhere between Scenario 1

and 2

20

Measurements of the 125 GeV boson

21

•  Mass & width are hard to improve beyond Run 2 •  Direct measurement of width limited by resolution

•  Dominant spin/parity will probably be established as 0+

•  Investigate a CP-violating contribution •  At LHC, we can only measure σ×BR. Express a ratio µ to SM

value. •  Ratios of partial widths can be made without further

assumptions •  Interpretation as coupling measurements is model dependent g

gHb,t

b,tκ

q q

q qH

W,ZW,Z

W,Zκ

q

q

H

W,ZW,Z

W,Zκ

g

g

t

tH

tt

tκ

HW,Z

W,ZW,Zκ

γ

γ

H W,b,tW,b,tκ

Hτb,

τb,τb,κ

125 GeV Higgs Couplings at the HL-LHC •  ATLAS has performed projection studies to HL-LHC,

assuming up to 3000 fb-1 of data •  focused on the main channels already under study with

LHC data, plus a few rare decay channels sensitive to top and muon couplings

•  ZH,Hàbb was studied, but S/B is bad and it it very difficult at present to estimate systematic uncertainties at L=5x1034 cm-2 s-1 è not included in the available ES ATLAS studies

ggF VBF H WH ZH ttH

Hγγ ✔ ✔ ✔ ✔ ✔ HZZ* ✔

HWW* ✔ ✔ ✔ Hττ extrap. ✔ Hµµ ✔ ✔

22

ATL-‐PHYS-‐PUB-‐2012-‐004

ttH, Hàγγ and Hàµµ

•  One of the best channels to study Higgs boson couplings to fermions

•  Very rare: deviations from the expected rate would indicate new physics –  Large background from Zàµµ

•  Analysis included background modeling uncertainties

•  More than 6 sigma at L=3000 fb-1

•  Important for H-top coupling measurement

•  Require multi-jet high-pT jets •  Analyse 1-lepton and 2- lepton

events •  Require very high luminosity

–  S/√B ~ 6 –  A factor 2 better than 300 fb-1

23

Higgs boson couplings in SM

24

Higgs boson couplings in SM

25

Par9al widths are propor9onal to the coupling square

Higgs boson signal strength

•  Measurements of the signal strength parameter mu for mH = 125GeV for the individual channels and for their combination.

26

)µSignal strength ( -1 0 +1

Combined

4l (*) ZZH

H

l l (*) WWH

H

bbW,Z H

-1Ldt = 4.6 - 4.8 fb = 7 TeV: s-1Ldt = 13 fb = 8 TeV: s

-1Ldt = 4.6 fb = 7 TeV: s-1Ldt = 13 fb = 8 TeV: s


-1Ldt = 13 fb = 8 TeV: s



= 125 GeVHm

0.24± = 1.35 µ

ATLAS Preliminary

μif = μi × μf = μ

Higgs boson event production

•  k = analysis category •  i = production mode •  f = decay final state •  nk

signal = number of selected signal events by the k final state •  L = integrated luminosity •  σi,SM = production cross section •  Bf,SM = finale state branching ratio •  µi = production mode signal strength •  µf = final state branching ratio strength •  A = detector acceptance •  ε = reconstruction and selection efficiency

27

Statistical procedure

•  Write the likelihood function – Example: do this for one channel/decay-final-state

28

•  The Profile Likelihood ratio; –  here µ is the array of the various µi entering the likelihood function –  θ(µ) is the array of the nuisance parameters

•  the production rate of events in the various analysis categories can be expressed directly in terms of the Higgs boson couplings, starting from the expression, and using the coupling constants at the place of the partial widths (including production):

29

•  example: the Higgs boson production in the WH channel with decay to ZZ: σ(WH) x BR(HàZZ) = σ(WH)SM x BR(HàZZ)SM x (k2

W k2Z)/k2

H

ΓH = ΣΓi

q

q

H

W,ZW,Z

W,Zκ

•  the production rate of events in the various analysis categories can be expressed directly in terms of the Higgs boson couplings, starting from the expression, and using the coupling constants at the place of the partial widths (including production):

30

•  example: the Higgs boson production in the WH channel with decay to ZZ: σ(WH) x BR(HàZZ) = σ(WH)SM x BR(HàZZ)SM x (k2

W k2Z)/k2

H

ΓH = ΣΓi

•  Warning! At LHC we don’t measure the Higgs boson production cross section nor ΓH !

31

•  As a consequence, we have two ways to proceed: – Make assumptions on ΓH è model dependent

measurements – Make ratio of measurements, given that they are ΓH

independent

•  Warning! At LHC we don’t measure the Higgs boson production cross section nor ΓH !

Higgs Couplings

32

Theoretical uncertainties

33

•  Theoretical predictions for known and new processes are critical •  Missing higher order (QCD) radiative corrections are estimated by

varying factorisation and renormalisation scales (0.5 ~ 2.0) •  Electroweak corrections •  Treatment of heavy quarks •  PDF uncertainties (which also depend on the order of calculation

available) •  mH=125 GeV @ 14 TeV: σ(pp(gg)àH+X) scale +9

-12%, PDF ±8.5%

•  PDF uncertainties can be reduced by future precise experimental measurements at LHC, including •  W, Z σ and differential distributions for lower x quarks •  High mass Drell-Yan measurements for higher x quarks •  Inclusive jets, dijets for high x quarks and gluons •  Top pair differential distributions for medium/large x gluons •  Single top for gluon and b-quark •  Direct photons for small/medium x gluons

Higgs Couplings at the HL-LHC

Left: Expected measurement precision on the signal strength µ = (σ×BR)=(σ×BR)SM in all considered channels. Right: Expected measurement precisions on ratios of Higgs boson partial widths without theory assumptions on the particle content in Higgs loops or the total width.

34


Left: Expected measurement precision on the signal strength µ = (σ×BR)=(σ×BR)SM in all considered channels. Right: Expected measurement precisions on ratios of Higgs boson partial widths without theory assumptions on the particle content in Higgs loops or the total width.

Expected precision for the determination of the coupling scale factors kV and kF. No additional BSM contributions are allowed in either loops or in the total width (numbers in brackets include current theory systematic uncertainties). 35


•  Coupling CMS projection: In the first one (Scenario 1) all systematic uncertainties are kept unchanged. In the second one (Scenario 2) the theoretical uncertainties are scaled by a factor of 1/2, while other systematical uncertainties are scaled by the square root of the integrated luminosity.

Couplings can be measured at the level of 5 % or better

36

Are the ATLAS and CMS results consistent?

37

(1) ATLAS uncertainty based on old result (2) ATLAS uncertainty extrapolated with CMS approach

Channel Uncertainty on mu value with 300 F-‐1 [%]

Experimental only Experimental + theory

ATLAS CMS ATLAS CMS

γγ 8 5 15 15

ZZ 9 8 16 11

WW (1) 26 9 29 14

ττ (2) 11 9 15 11

ττ 19 9 23 11

Some proposals for future colliders

38

LEP3

TLEP/VHE-‐LHC CLIC

See also: arxiv:1302.3318

125 GeV Higgs boson CP mixing

42

Higgs boson CP mixing in HàZZà4l •  Explore the ATLAS sensitivity to the CP-violating part of the HZZ

scattering amplitude:

•  ε: polarisation vectors of the gauge bosons, form factors a1 and a2 refer to CP-even boson with mass MX, a3 to a CP-odd boson –  The presence of the two CP terms can lead to CP violation –  In SM a1=1; a2=a3=0

•  In this study we have set a1=1; a2=0, and varied a3

Expected significances in sigma to reject a CP-violating state in favour of 0+ hypothesis as a function of integrated luminosity for various strength of CP-violating contribution.

Measurement of “large” form factors can be seen with ~100 fb-1. A similar conclusion can be drawn for the observation of anomalous form factor a2

From

Eur

opea

n St

rate

gy P

UB

Not

e

43

fa3 > 0.46 fa3 > 0.63

HH production at HL-LHC •  The only way to reconstruct the scalar potential of

the Higgs doublet field , that is responsible for spontaneous electroweak symmetry breaking, it is necessary to measure the Higgs boson self–interactions

44

1 Introduction

A bosonic particle with a mass of about 125 GeV has been observed by the ATLAS andCMS Collaborations at the LHC [1] and it has, grosso modo, the properties of the longsought Higgs particle predicted in the Standard Model (SM) [2]. This closes the firstchapter of the probing of the mechanism that triggers the breaking of the electroweaksymmetry and generates the fundamental particle masses. Another, equally importantchapter is now opening: the precise determination of the properties of the producedparticle. This is of extreme importance in order to establish that this particle is indeed therelic of the mechanism responsible for the electroweak symmetry breaking and, eventually,to pin down e!ects of new physics if additional ingredients beyond those of the SM areinvolved in the symmetry breaking mechanism. To do so, besides measuring the mass,the total decay width and the spin–parity quantum numbers of the particle, a precisedetermination of its couplings to fermions and gauge bosons is needed in order to verifythe fundamental prediction that they are indeed proportional to the particle masses.Furthermore, it is necessary to measure the Higgs self–interactions. This is the only wayto reconstruct the scalar potential of the Higgs doublet field ", that is responsible forspontaneous electroweak symmetry breaking,

VH = µ2"†"+1

2!("†")2 ; ! =

M2H

v2and µ2 = !

1

2M2

H , (1)

with v = 246 GeV. Rewriting the Higgs potential in terms of a physical Higgs boson leadsto the trilinear Higgs self–coupling !HHH , which in the SM is uniquely related to the massof the Higgs boson,

!HHH =3M2

H

v. (2)

This coupling is only accessible in double Higgs production [3–6]. One thus needs toconsider the usual channels in which the Higgs boson is produced singly [7], but allowsfor the state to be o! mass–shell and to split up into two real Higgs bosons. At hadroncolliders, four main classes of processes have been advocated for Higgs pair production:

a) the gluon fusion mechanism, gg " HH , which is mediated by loops of heavy quarks(mainly top quarks) that couple strongly to the Higgs boson [8–11];

b) the WW/ZZ fusion processes (VBF), qq! " V "V "qq! " HHqq! (V = W,Z), whichlead to two Higgs particles and two jets in the final state [8, 12, 13];

c) the double Higgs–strahlung process, qq̄! " V " " V HH (V = W,Z), in which theHiggs bosons are radiated from either a W or a Z boson [14];

d) associated production of two Higgs bosons with a top quark pair, pp " tt̄HH [15].

As they are of higher order in the electroweak coupling and the phase space is smalldue to the production of two heavy particles in the final state, these processes have muchlower production cross sections, at least two orders of magnitude smaller, compared to thesingle Higgs production case. In addition, besides the diagrams with H" " HH splitting,there are other topologies which do not involve the trilinear Higgs coupling, e.g. withboth Higgs bosons radiated from the gauge boson or fermion lines, and which lead to the

2

1 Introduction

A bosonic particle with a mass of about 125 GeV has been observed by the ATLAS andCMS Collaborations at the LHC [1] and it has, grosso modo, the properties of the longsought Higgs particle predicted in the Standard Model (SM) [2]. This closes the firstchapter of the probing of the mechanism that triggers the breaking of the electroweaksymmetry and generates the fundamental particle masses. Another, equally importantchapter is now opening: the precise determination of the properties of the producedparticle. This is of extreme importance in order to establish that this particle is indeed therelic of the mechanism responsible for the electroweak symmetry breaking and, eventually,to pin down e!ects of new physics if additional ingredients beyond those of the SM areinvolved in the symmetry breaking mechanism. To do so, besides measuring the mass,the total decay width and the spin–parity quantum numbers of the particle, a precisedetermination of its couplings to fermions and gauge bosons is needed in order to verifythe fundamental prediction that they are indeed proportional to the particle masses.Furthermore, it is necessary to measure the Higgs self–interactions. This is the only wayto reconstruct the scalar potential of the Higgs doublet field ", that is responsible forspontaneous electroweak symmetry breaking,

VH = µ2"†"+1

2!("†")2 ; ! =

M2H

v2and µ2 = !

1

2M2

H , (1)

with v = 246 GeV. Rewriting the Higgs potential in terms of a physical Higgs boson leadsto the trilinear Higgs self–coupling !HHH , which in the SM is uniquely related to the massof the Higgs boson,

!HHH =3M2

H

v. (2)

This coupling is only accessible in double Higgs production [3–6]. One thus needs toconsider the usual channels in which the Higgs boson is produced singly [7], but allowsfor the state to be o! mass–shell and to split up into two real Higgs bosons. At hadroncolliders, four main classes of processes have been advocated for Higgs pair production:

a) the gluon fusion mechanism, gg " HH , which is mediated by loops of heavy quarks(mainly top quarks) that couple strongly to the Higgs boson [8–11];

b) the WW/ZZ fusion processes (VBF), qq! " V "V "qq! " HHqq! (V = W,Z), whichlead to two Higgs particles and two jets in the final state [8, 12, 13];

c) the double Higgs–strahlung process, qq̄! " V " " V HH (V = W,Z), in which theHiggs bosons are radiated from either a W or a Z boson [14];

d) associated production of two Higgs bosons with a top quark pair, pp " tt̄HH [15].

As they are of higher order in the electroweak coupling and the phase space is smalldue to the production of two heavy particles in the final state, these processes have muchlower production cross sections, at least two orders of magnitude smaller, compared to thesingle Higgs production case. In addition, besides the diagrams with H" " HH splitting,there are other topologies which do not involve the trilinear Higgs coupling, e.g. withboth Higgs bosons radiated from the gauge boson or fermion lines, and which lead to the

2

gluon-‐gluon fusion Vector Boson Fusion

Higgs-‐strahlung

Higgs boson Self-Coupling A. Djouadi, et al., Eur. Phys. J. C10 (1999), 45

σHH (14 TeV) = 33.89 +18%-15% (QCD) ±7% (PDF+αS) ±10% (EFT) fb +37.2 -29.8 fb A. Djouadi, et al., hgp://arxiv.org/abs/1212.5581

45

Higgs Self-Coupling

•  The “trouble” with a 125 GeV Higgs: it decays in many final states with similar “small” B.R. This is very good for couplings, but opens real challenges for HH final states, characterized by small production rates.

•  The selection of HH processes has to account for: –  Final states experimentally clear and robust –  Final states with large enough production

rates

Expected SM HH yields for proton-proton collisions at √s = 14 TeV and L=3000 fb-1

Two channels have been considered by ATLAS for the “European Strategy”:

1.  HHbbWW 2.  HHbbγγ

46

ATL-‐PHYS-‐PUB-‐2012-‐004

HHàbbWW •  BR ~ 25% à 2.6 × 104 events in 3000 fb-1 at 14 TeV; –  This includes all W decay modes

•  The ttbar process represents a severe background for this final state;

•  Study done considering one W decaying hadronically, the other leptonically (e,µ; treated separately)

•  Select events with high lepton pT, large missing transverse energy, four high-pT jets, of which two b-tagged;

•  The result of the study shows how challenging is extract HH production from this channel –  We select <~ 1000 signal events on top of 107 ttbar events –  S/B in agreement with estimates performed by other

authors (M.J. Dolan et al., arXiv:1206.5001v2 [hep-ph])

47

HH à bbγγ •  BR ~ 0.27% , σ × BR ~ 0.09 fb à 260 HH events

in 3000 fb-1 at 14 TeV; •  bbγγ, ZH, Zbb, Hbb, ttbar are important

backgrounds •  Select events with high-pT photons, two jets b-

tagged; reconstruct the invariant mass of the b-jets and of the photons and select events with mγγ and mbb = mZ within experimental mass resolution

•  Initial studies presented performed for the European Stratgey indicate that this channel is promising –  Soon preliminary results at the ECFA HL-LHC

Workshop

48

HH à bbττ •  BR ~ 7.4% , σ × BR ~ 0.22 fb à 7500 HH events

in 3000 fb-1 at 14 TeV; •  Ttbar is the most dangerous background; other

backgrounds are bbττ, Zbb, Hbb •  Some authors have submitted papers where

extremely encouraging; recent analyses done by ATLAS and still on going, based on more realistic assumptions on tau and b-quark reconstruction, indicate how much challenging this channel is.

•  More work is still needed before making a statement on this final state.

49

Vector Boson Scattering •  In the Standard Model, the Higgs boson preserves

the unitarity of scattering amplitudes in longitudinal Vector Boson Scattering (VBS)

•  However new physics can contribute to the regularization of of the VBS cross-section or else enhancing it. – Example: in Technicolor models predict the

appearance of resonances in the V-V invariant mass distribution

•  è the study of VBS properties at the LHC is a mandatory step to test the effects of the SM Higgs boson (if the existence will be confirmed) or from New Physics BSM.

50

Vector Boson Scattering •  At LHC VBS are tagged with two forward high-pT jets on

either side, the remnants of the quarks that have emitted the W/Z bosons in the central rapidity region: WW+2jets, WZ+2jets, ZZ+2jets

•  ATLAS has performed preliminary studies of the process ppà ZZjj à 4l+jj within the “Pade’” unitarization (IAM, Inverse Amplitude Method) and using the WHIZARD generator (it allows to generate weak boson scattering mediated by a new high-mass resonance in presence of a Higgs boson with 126 GeV mass)

[TeV]jj

leading m0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

Entri

es

20406080

100120140160180200220240

SM VV

DibosonNon-VV

(g = 1.75)1.0 TeV Res SM VV +

-1 L dt = 3000 fb! (Simulation)

PreliminaryATLAS

[TeV]4lm0.2 0.3 0.4 0.5 0.6 1

Entri

es

10

20

30

40

50 SM VV

DibosonNon-VV

(g = 1.75)1.0 TeV Res SM VV +


PreliminaryATLAS

51

Vector Boson Scattering •  At LHC VBS are tagged with two forward high-pT jets on

either side, the remnants of the quarks that have emitted the W/Z bosons in the central rapidity region: WW+2jets, WZ+2jets, ZZ+2jets

•  ATLAS has performed preliminary studies of the process ppà ZZjj à 4l+jj within the “Pade’” unitarization (IAM, Inverse Amplitude Method) and using the WHIZARD generator (it allows to generate weak boson scattering mediated by a new high-mass resonance in presence of a Higgs boson with 126 GeV mass)

[TeV]4lm0.2 0.3 0.4 0.5 0.6 1

Entri

es

10

20

30

40

50 SM VV

DibosonNon-VV

(g = 1.75)1.0 TeV Res SM VV +


PreliminaryATLAS

Summary of the expected sensitivity to anomalous VBS signal for a a few values of the mass of the resonance and of the coupling g.

52

SUSY @ HL-LHC: the end of Naturalness?

53

By G. Polesello

SUSY Searches •  So far there has been no sign of Supersymmetry at

LHC – However only < 10% of the LHC expected data have

been studied (and at √s=7 TeV) –  3rd generation squarks have low cross-sections

•  If we find it: – We have a large set of new particles to study – Thus a SUSY discovery will mandate more luminosity

•  If will not find it by 2020: – HL-LHC offers a 25% increase in mass reach – HL-LHC will explore a phase space no other machine

will probe for decades 54

Searches for stop •  Probably this will be

one of the most important points in SUSY for the immediate future: naturalness requires stop mass not larger than ~ 1 TeV

•  Rates will be modest è HL-LHC reprsents an ideal machine for this search

The 95% CL exclusion limits for 3000 fb-1 (dashed) and 5 sigma discovery reach (solid) for 300 fb-1 and 3000 fb-1 in the stop, neutralino_1 mass plane assuming:

55

Future Searches •  “Naturalness” dictates: –  Stop < 700 GeV –  Gluino < 1500 GeV

•  Dedicated searches for direct stop/sbottom and EW gaugino production will be a focus for therest of the 8 TeV run •  Can more complex models accommodate Naturalness?

by J. Hewett

Weak-scale Supersymmetry extremely well motivated: Don’t give up on Weak-scale SUSY until 14 TeV with 300 fb-1 !

Electroweak production of neutralinos, and charginos

•  LHC can also probe electroweak production of charginos, neutralinos and sleptons.

• 

57

eg. ATLAS χ̃±1 and χ̃02 discovery potentialincreased from 500 GeV to TeV scale.

χ̃±1

χ̃02

W

Zp

p

χ̃01

�

ν

χ̃01

�

�

Mass (GeV)2

0!" and

1

±!"

100 200 300 400 500 600 700 800

Ma

ss (

Ge

V)

10!"

100

200

300

400

500

600

700 ATLAS Simulation

, 95% exclusion limit-13000 fb

discovery reach#, 5-13000 fb

, 95% exclusion limit-1300 fb

discovery reach#, 5-1300 fb

=14 TeVs

Searches for squarks and gluinos •  HL-LHC gives tight

limits: –  ~ 3 TeV for squarks –  ~ 2.5 TeV for gluinos

•  This represents a 400 GeV rise in sensitivity with respect to the L=300 fb-1 case The 95% CL exclusion limits (solid lines) and 5 sigma discovery reach (dashed lines) in a simplified squark--gluino model with massless neutralino with 300 fb-1 (blue lines) and 3000 fb-1 (red lines). The colour scale shows √s=14 TeV NLO production cross section calculated by Prospino 2.1.

58

Exotics Searches •  Searches for ttbar resonances or Z’ leptons can

exploit the physics potential offered by HL-LHC

[GeV]KK

gm3000 4000 5000 6000 7000 8000 9000 10000

B [pb]

!

-410

-310

-210

-110

1

10

210

310

410

510 = -0.20

s/g

KKqqg

g

Expected limit! 1±Expected ! 2±Expected Preliminary

(Simulation)

ATLAS

t t "KK

g

= 14 TeVs

-1 L dt = 3000fb#

•  Main challenges: – Reconstruct highly boosted top decays – Ensure lepton measurement at very high pT

•  Muon system alignment •  Leakage from calorimeter (?)

Summary of the expected limits for gKKà ttbar and Z’

Topcoloràttbar searches in the lepton+jets (dilepton) channel and of Z’SSM à ee and Z’SSMà µµ searches in the Sequential Standard Model. All boson mass limits are quoted in TeV.

59

)! q"BR(t

-510 -410 -310 -210 -110 1

qZ

)"

BR

(t

-510

-410

-310

-210

-110

1

LEP

(q=u only) ZEUS

(q=u only) H1

D0

CDF

)-1ATLAS (2 fb

)-1CMS (4.6 fb

ATLAS Simulationextrapolated to 14 TeV:

-1300 fb(sequential)

-13 ab(sequential)

-13 ab(discriminant)

95% C.L.EXCLUDEDREGIONS

FCNC in top decays •  Opportunity to search for rare processes •  BR(tàbW)~1, BR(tàsW)<0.18%, BR(tàdW)<0.02%

•  Approaching few 10-5 precision

Pippa Wells, CERN June 2013 60

BR FCNC t→ qγ t→ qZSM 10−14 10−14

QS 10−9 10−4

2HDM 10−6 10−7

MSSM 10−6 10−6

RPV SUSY 10−6 10−5

TC2 10−6 10−4

RS 10−9 10−5

Conclusions •  A data sample of 300 fb-1 at the LHC will allow to

exclude strong deviations of the Higgs-like particle recently discovered from the Higgs boson predicted by Standard Model

•  A complete investigation on the physics properties of this new boson will require the search for rare decay final states, selfcoupling processes, CP violation effects, as well as the reduction of experimental (and theoretical) uncertainties è High-Luminosity LHC with L=3000 fb-1 can provide the required statistics with an accuracy on the Higgs couplings in the range of 1-4%;

•  HL-LHC extends the searches of LHC of BSM physics, and offers the required data to study the properties of new particles if found at the LHC 61

… and many other physics studies!

62

backup

63

Physics Prospects - introduction

64

•  Emphasis on prospects with “LHC” 300 fb-1 and “HL-LHC” 3000 fb-1 •  ATLAS has implemented functions to transform from generator level

“truth” to reconstructed physics objects for HL-LHC •  Based on present detector with realistic/pessimistic assumptions on the

effect of pileup of up to ~140 (for L=5 × 1034 cm-2s-1) •  eg. b-tagging performance from fully simulated ITk now shown to be

better than that assumed for physics studies. •  CMS extrapolate from the present analyses with different scenarios

1.  Experimental systematic and theoretical uncertainties unchanged. (Statistical uncertainties scale with 1/√L)

2.  Statistical and experimental systematic uncertainties scale with 1/√L, theoretical uncertainties are reduced by a factor 2.

3.  Experimental errors unchanged, theoretical uncertainties zero

•  i.e. systematic uncertainties are always included, with different assumptions on possible detector/algorithm/theoretical improvements

backup

65

[GeV]4lm

Even

ts /

3 G

eV

0

10

20

30

100 200 400 800

Data = 126 GeVH m*, ZZγ Z

Z+X

CMS preliminary

-1 = 8 TeV: L = 19.6 fbs -1 = 7 TeV: L = 5.1 fbs

Higgs boson

•  Distribution of the 4-lepton invariant mass obtained with the data recorded with the CMS detector

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