Higgs Physics at CLIC Frank Simon Max-Planck-Institute for Physics PANIC 2014 Hamburg, August 2014 on behalf of CLICdp
Outline • CLIC: A future TeV-scale e + e - Collider � • The Higgs Program at CLIC • couplings at 350 GeV, 1.4 TeV and 3 TeV • the top Yukawa coupling • the Higgs self-coupling � • Global fits � • Summary Higgs Physics at CLIC 2 Frank Simon (fsimon@mpp.mpg.de) PANIC2014, Hamburg, August 2014
CLIC - A Possible Future at CERN CLIC, a linear e + e - collider at the energy frontier • Based on two-beam acceleration, room-temperatur cavities, gradients of up to 100 MV/m • Maximum energy 3 TeV, construction in stages • high luminosity (a few x 10 34 cm -2 s -1 ) Higgs Physics at CLIC 3 Frank Simon (fsimon@mpp.mpg.de) PANIC2014, Hamburg, August 2014
A Staged Program to maximize Physics Potential First stage luminosity optimised (scenario A) • For optimal luminosity, the energy of a collider ] -1 Integrated luminosity Integrated luminosity [fb based on CLIC technology can only be tuned Total 3000 1% peak within a factor of ~ 3: Staged construction of 0.5 TeV 1.4 TeV 3 TeV the machine 2000 Provides: • earlier start of physics 1000 • optimal use of physics potential • Precise energy of the stages depends on 0 0 5 10 15 20 physics - with considerations for technical constraints: Year • Studied scenario: • 350 / 375 GeV (500 fb -1 ) • Higgs (including total width), Top threshold scan • 1.4 TeV (1.5 ab -1 ) • BSM physics, ttH, Higgs self-coupling, rare Higgs decays • 3 TeV (2 ab -1 ) • BSM physics, Higgs self-coupling, rare Higgs decays Higgs Physics at CLIC 4 Frank Simon (fsimon@mpp.mpg.de) PANIC2014, Hamburg, August 2014
The CLIC Environment • The main challenge: High energy and high luminosity leads to high rates of photon-induced processes: Combined with bunch structure γ / γ ∗ q (0.5 ns between BX): Pile-up of hadronic background: ~ 19 TeV in HCAL / bunch train γ / γ ∗ q ➫ Needs to be rejected by γγ → hadrons interactions: reconstruction e + e - pairs drive 3.2 / bunch crossing @ 3 TeV crossing angle & vertex detector radius Higgs Physics at CLIC 5 Frank Simon (fsimon@mpp.mpg.de) PANIC2014, Hamburg, August 2014
The CLIC Environment • The main challenge: High energy and high luminosity leads to high rates of photon-induced processes: Combined with bunch structure γ / γ ∗ q (0.5 ns between BX): Pile-up of hadronic background: ~ 19 TeV in HCAL / bunch train γ / γ ∗ q ➫ Needs to be rejected by γγ → hadrons interactions: reconstruction e + e - pairs drive 3.2 / bunch crossing @ 3 TeV crossing angle dN/dE & vertex detector radius 0.02 77% > 0.99 √ s @ 350 GeV 35% > 0.99 √ s @ 3 TeV 0.015 A further consequence of radiative losses: The 0.01 luminosity spectrum - characterized by a main peak and a tail to lower energies 0.005 0 0 1000 2000 3000 s' [GeV] Higgs Physics at CLIC 5 Frank Simon (fsimon@mpp.mpg.de) PANIC2014, Hamburg, August 2014
Detectors & Event Reconstruction at CLIC • CLIC detectors: Low-mass, high resolution vertexing & tracking and highly granular calorimeters with time- stamping capability, all in a large high-field solenoid • Event reconstruction based on Particle Flow Algorithms ‣ Provides optimal jet energy reconstruction ‣ When combined with ns-level timing in the calorimeters and hadron-collider type jet finders: A powerful tool for the rejection of γγ → hadrons background Higgs Physics at CLIC 6 Frank Simon (fsimon@mpp.mpg.de) PANIC2014, Hamburg, August 2014
Detectors & Event Reconstruction at CLIC • CLIC detectors: Low-mass, high resolution vertexing & tracking and highly granular calorimeters with time- stamping capability, all in a large high-field solenoid • Event reconstruction based on Particle Flow Algorithms ‣ Provides optimal jet energy reconstruction ‣ When combined with ns-level timing in the calorimeters and hadron-collider type jet finders: A powerful tool for the rejection of γγ → hadrons background Reduction of background from 19 TeV to 100 GeV: Challenging CLIC environment under 1.2 TeV of background control! e + e − → t ¯ t @ 3 TeV Higgs Physics at CLIC 6 Frank Simon (fsimon@mpp.mpg.de) PANIC2014, Hamburg, August 2014
Higgs Physics at CLIC • Now a guaranteed physics program - Profits from the wide energy reach of CLIC HX) [fb] H ν ν e e 2 10 + - H e e → 10 - H Z e t t H + (e 1 σ H H ν ν e e -1 10 H H Z -2 10 0 1000 2000 3000 s [GeV] Higgs Physics at CLIC 7 Frank Simon (fsimon@mpp.mpg.de) PANIC2014, Hamburg, August 2014
Higgs Physics at CLIC • Now a guaranteed physics program - Profits from the wide energy reach of CLIC HX) [fb] H ν ν e e 2 10 + - H e e → 10 - H Z e t t H + (e 1 σ H H ν ν e e -1 10 H H Z -2 10 0 1000 2000 3000 s [GeV] ~ 80k ~ 450k Higgs bosons per stage (w/o polarization) ~ 1 M ( Polarization (80%, 0%) provides a boost of 1.8 for WW fusion ) Main production modes - give access to couplings and total width Higgs Physics at CLIC 7 Frank Simon (fsimon@mpp.mpg.de) PANIC2014, Hamburg, August 2014
Higgs Physics at CLIC • Now a guaranteed physics program - Profits from the wide energy reach of CLIC HX) [fb] H ν ν e e 2 10 + - H e e → 10 - H Z e t t H + (e 1 σ H H ν ν e e -1 10 H H Z -2 10 0 1000 2000 3000 s [GeV] ~ 80k ~ 450k Higgs bosons per stage (w/o polarization) ~ 1 M ( Polarization (80%, 0%) provides a boost of 1.8 for WW fusion ) Main production modes - give access to couplings and total width Rarer Processes - ZZ fusion, direct access to top Yukawa, self-coupling Higgs Physics at CLIC 7 Frank Simon (fsimon@mpp.mpg.de) PANIC2014, Hamburg, August 2014
Exploring the Higgs Sector: Couplings • The measurements at CLIC (and other lepton colliders) are: σ x BR (for specific Higgs decays) σ (for model-independent recoil mass analysis) Both are sensitive to couplings: σ recoil ∝ g 2 HZZ σ × BR(H → ff ) ∝ g 2 Hii g 2 H ff Γ tot Higgs Physics at CLIC 8 Frank Simon (fsimon@mpp.mpg.de) PANIC2014, Hamburg, August 2014
Exploring the Higgs Sector: Couplings • The measurements at CLIC (and other lepton colliders) are: σ x BR (for specific Higgs decays) σ (for model-independent recoil mass analysis) Both are sensitive to couplings: σ recoil ∝ g 2 HZZ σ × BR(H → ff ) ∝ g 2 Hii g 2 H ff Γ tot A crucial ingredient: The total width - best results when combining ZH and VBF σ (H ν e ν e ) × BR(H → WW ∗ ) ∝ g 4 ➫ Accessible at 350 GeV HWW (134 fb for ZH, 52 fb for H νν ) Γ tot σ ( e + e − → ZH) × BR(H → b ¯ b ) ∝ g 2 b ) g HWW pinned down with model- HZZ σ ( e + e − → H ν e ν e ) × BR(H → b ¯ g 2 independent g HZZ and HWW high-BR H->bb decay Higgs Physics at CLIC 8 Frank Simon (fsimon@mpp.mpg.de) PANIC2014, Hamburg, August 2014
Simulation Studies • All based on GEANT4 simulations using detailed detector models and realistic event reconstruction including PFA • Beam-induced and physics backgrounds included • Statistical uncertainties assume unpolarised beams Higgs Physics at CLIC 9 Frank Simon (fsimon@mpp.mpg.de) PANIC2014, Hamburg, August 2014
Model-Independent Measurement of Coupling to Z Events • A unique feature of lepton colliders: Input total 250 Fitted total model-independent measurement of Fitted signal 200 HZZ coupling Fitted background 150 Z -> µµ (350 GeV, 500 fb -1 ) 100 50 √ s m 2 rec = s + m 2 Z − 2 E Z 0 100 150 200 M [GeV] Absolute measurement of HZ cross section: recoil ~ 4.2% (stat) for leptonic Z decays at 350 GeV Higgs Physics at CLIC 10 Frank Simon (fsimon@mpp.mpg.de) PANIC2014, Hamburg, August 2014
Model-Independent Measurement of Coupling to Z Events • A unique feature of lepton colliders: Input total 250 Fitted total model-independent measurement of Fitted signal 200 HZZ coupling Fitted background 150 Z -> µµ (350 GeV, 500 fb -1 ) 100 50 √ s m 2 rec = s + m 2 Z − 2 E Z 200 /GeV 0 100 150 200 180 M [GeV] Absolute measurement of HZ cross section: recoil rec ~ 4.2% (stat) for leptonic Z decays at 350 GeV m 160 Substantial improvement when using hadronic Z decays 140 • The challenge: Z->qq reconstruction and 120 event identification may depend on H decay mode ‣ Very small bias through optimised analysis 100 Including hadronic Z decays: Δσ / σ (HZ) = 1.65% (stat) 80 70 80 90 100 110 120 130 m /GeV qq Higgs Physics at CLIC 10 Frank Simon (fsimon@mpp.mpg.de) PANIC2014, Hamburg, August 2014 n o i s i v
Δ𝜏 ��� � Coupling Measurements at 350 GeV 𝑂 ���� • Determine limit to invisible BSM Higgs decays Δ𝜏 ��� = 𝑂 ���,���% based on 2-jet events in HZ, with Z->qq. • Resolution on fraction of invisible decays is � limited by physics background fluctuations: Δσ x BR inv = 0.57% 𝚬𝝉 𝒋𝒐𝒘 = 𝟏. 𝟔𝟖% Higgs Physics at CLIC 11 Frank Simon (fsimon@mpp.mpg.de) PANIC2014, Hamburg, August 2014
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