Higgs Physics, after July PDF Free Download

Higgs Physics, after July 2012 C.-P. Yuan Michigan State University, USA July 10, 2013 @ IHEP

July 4, 2012 Scientists at CERN say they've found a new particle consistent with the Standard Model Higgs boson with 5-sigma certainty a false positive probability of about 1 in 9 trillion. This is hardly the end of the road for Higgs study, though. It s only the beginning. So a Higgs-like boson has been discovered. What s next?

What do we know about this New Boson Its mass is between 124 GeV and126 GeV Its production rates in various decay channels have been found to be in good agreement with the Standard Model (SM) predictions. The Higgs boson couplings to any SM particles are found to generally agree with SM predictions within 20%.

A New Boson

ATLAS Moriond EW 2013 ATLAS-CONF-2013-034,012,013

CMS Moriond EW 2013 CMS-PAS-HIG-13-001,2 CMS-PAS-HIG-12-045

Data and Theory The observed Higgs event number is proportional to the product of Higgs Production cross section and Higgs decay branching ratio into a specific decay channel (i.e. detection mode). arxiv: 1101.0593

SM Higgs @ 14 TeV LHC

Higgs decay branching ratios For 125 GeV Higgs, Total decay width is 4.03 MeV. Br bb = 0.58 Br WW = 0.22 Br gg = 0.086 Br ττ = 0.06 Br cc = 0.028 Br ZZ = 0.027 Br γγ = 0.0023 Br Zγ = 0.0016

What do we know about these couplings? Assuming No BSM Decays Test Consistency of SM

Post Moriond 2013 Fits: Falkowski, et. al., arxiv: 13031812 Giardino, et. al., arxiv: 1303.3570 Ellis, et. al., arxiv: 1303.3879 (ATLAS and CMS)

Properties of the Higgs Boson All masses proportional to H =v, hence L SM and M 2 W 1+ H v 2 W +µ W µ Important loop effects gluon L SM X f m f 1+ H v + M 2 Z 2 1+ H v 2 Z µ Z µ Lf Rf + h.c. gluon (pp! H) (H! ) non-decoupling!

Allow Couplings to Float within SM g htt g HWW

Allow Couplings to Float within SM t g hxx = m v Z b W g hxx = M 2 v 2 τ Scott Thomas Ellis and You

The Future? t b W Z H? τ μ Scott Thomas

What accounts for Vector Boson Mass Generation? Higgs Mechanism Electroweak Symmetry Breaking (EWSB) The Standard Model Higgs Boson Make the Higgs Composite: Little Higgs Make the (Multiple) Higgs Natural: Supersymmetry

The Higgs Mechanism (EWSB) W + W

Trial answer: the SM with a Higgs

Matrix Notation

Non-linear Representation

Custodial Symmetry: SU(2)V

Custodial Symmetry is an important part of any theory of EWSB! SU(2)V

Violations of Custodial Symmetry (i.e. mass differences)

Problems with the Higgs Model Problems with the Higgs Model No (other?) fundamental scalars observed in nature No explanation of dynamics responsible for Electroweak Symmetry Breaking Hierarchy or Naturalness Problem ( ) ( ) Triviality and Vacuum Stability Problems... m 2 ( ) References

Triviality and Vacuum Stability Triviality For 125 GeV Higgs, Λ 10 11 GeV with m t = 173 GeV Vacuum Stability

Updated Or: other particles (e.g. superpartners) could stablize the potential... Elias-Miro, et. al., arxiv:1112.3022

Further tests in the TeV region are absolutely needed Must study the longitudinally polarized vector boson scatterings in the TeV region to check the unitarity property. If the scattering amplitudes are shown to be unitary, then the discovered Higgs boson is responsible for the electroweak symmetry breaking. Otherwise, New Physics must exist to unitarize the longitudinal vector boson scatterings in the TeV region.

Electroweak Symmetry Breaking Loss of Unitarity in

Sum 0 SU(2) x U(1) @ E 4

SU(2) x U(1) @ E 2 & The Higgs ghww including (d+e) Lee, Quigg, Thacker

Weak Boson Scatterings in the TeV region Consider an Effective Chiral Lagrangian, with custodial symmetry (as g 0): Hep-ph/0211229

Dimension-6 Operators hep-ph/0303048 B Zhang, Y.-P. Kuang, H.-J. He, CPY

SU(2) x U(1) @ E & The Higgs t+ - t+ Z WL + WL - + t+ - t+ b WL + m te v 2 WL - t+ WL + Bad high-energy H behavior cancelled by: - t+ ghtt ghww WL - Chanowitz, Furman, Hinchliffe

Symmetry Magazine, Oct 30, 2012

Composite Higgs

Fundamental or Composite Higgs Boson Fundamental and Composite are in the eye of the calculator... more important: strong or weak interacting particle at electroweak symmetry breaking scale.

Composite Higgs Higgs as (Pseudo-)Goldstone Boson: Hard to do! V (h) = Cg2 16π 2 g 1 ( η 2 f 2 h 2 h 4 ) + η 4 2 +... Decay Constant Yields: h 2 η 2 η 4 f 2 ( But, EWPT: f>few TeV ) Must suppress η 2 without suppressing η 4 Georgi & Kaplan; Banks Chacko et. al., hep-ph/0510273

Little Higgs Theories Collective Symmetry Breaking: m 0 m 1 m 2 m N m N+1 k 1 k 2 k 3 k N k N+1 For weak springs, masses at end very weakly coupled! η 2 g2 In practice: m 2 h g2 16π 2 f 2 η 4 16π 2 Arkani-Hamed, Cohen, Georgi Meade, hep-ph/0402036

Little Higgs: The Hierarchy Cancellation of divergences by particles of same spin! T-Parity: minimize Z-pole effects & DM Schmaltz hep-ph/0210415

Cancellation of Λ 2 in top sector: Little Higgs Models ( λt λt λ T ) ( ) 2 2 2 2 ~ 0 Λ + =Λ (approximate) global symmetry relates T with t (Little Higgs mechanism) To ensure ρ=1 at tree level, T-parity was introduced. SM particles (t) T-partners (T P ) a) Lightest T-odd particle A H, dark matter candidate b) Need mass term for T P Induce new Higgs coupling (non-decoupling effects!!!)

Little Higgs Models σ(gg h) Large suppression in σ(gg h) ( ) LH σ( gg h) SM = σ( gg h) SM σ gg h Higgs couplings 3 2 9 2 v 2 f 2 v 2 f 2 (from T) (from T p ) v= h = 246 GeV Λ f 4π for f t ~ 1 3 4 v 2 f 2 h tot ~ 1 1 4 h ( LH ) ( SM ) Γ <Γ tot v 2 f 2

Discriminate New Physics Models using σ(gg h) Little Higgs models: σ(gg h) < σ(gg h) SM (destructive contributions from the partners of top quark to cancel quadratic divergence) Universal Extra-Dimension Models: σ(gg h) > σ(gg h) SM (additive contributions from KK states of top quark)

Little Higgs Models For m h ~ 100 GeV, Br(h γγ) LH up by ~ 20% Br(h bb) LH about the same down by ~ a factor of 2 for f = 700 GeV close to SM prediction could dramatically modify Higgs discovery potential at LHC for m h ~ 100 GeV becomes dominant discovery channel

Constraints On Composite Higgs D 4 interactions same as standard model! Higher dimension operators: ( D µ ) 2 f 2 ΔT 0, f > few TeV ( )D µ D µ s 4 Y 4 f 2 X f 2 q f 2 f 2 m q q q G aµ G a µ B µ B µ } g H = O v 2 f 2 = O(10%) Ignored on next page

Flavor-Universal Deviations Coupling to fermions Negative c region disfavored Coupling to vectors Ellis and You

Multiple Higgs, SUSY & Decoupling

Two-Higgs Model

Couplings to Fermions X ij Most general quark couplings: h u1ij q i L 1u j + u 2ij q i L 2u j + d 1ij q i L 1d j + d 2ij q i L 2d j i Fermion masses and Higgs couplings not diagonalized at same time! + h.c. Model-building solutions: Type-I : λ2u,d=0 One Higgs gives mass only to W and Z Type-II : λ2u=0 & λ1d=0 Each Higgs gives mass to only ups or downs md 1/sinβ, could have λt=λb Glashow and Weinberg, 1977

Limits on Two-Higgs Models Giardino, et. al.

SuperSymmetry Make the Higgs Boson natural! Higgs mass protected by chiral symmetry of partner Δm 2 H log(m 2 SUSY) λ g 2,g 2, mh bounded by ~130 GeV Why is μ of order a TeV?

SUSY Higgs Sector Limits Giardino, et. al.

Theory Summary Theory Fundamental Higgs Hierarchy Problem Precision EW ΛUV δgh/gh LHC YES! < 10 9 GeV 0% SUSY No MGUT? <10% Composite Higgs No f > few TeV 50 TeV O(10%) Dilaton No? 1-10 TeV O(100%) Higgsless/ TC No Ideal fermions 1-10 TeV no narrow scalar? What is the Higgs trying to tell us?

Precision Tests are needed New Physics effects (from heavy particles) could contribute in loops. Hence, precision tests of Higgs production cross sections and decay branching ratios are needed.

CTEQ-TEA PDF Global Analyses CTEQ-Tung et al (TEA) Collaboration: S. Dulat, J. Gao, M. Guzzi, T.J. Hou, J. Huston, H.-L. Lai, Z. Li, P. Nadolsky, J. Pumplin, D. Stump, C.-P. Yuan CT10NNLO (without including LHC data) is available via LHAPDF. Working on next generation CT PDFs with LHC W/Z and jet data included.

CT10NNLO and CT1X NNLO PDFs CT10 Website: http://hep.pa.msu.edu/cteq/public/ct10.html

CT10NNLO Hessian error PDFs Q=2 GeV Q=85 GeV

CT10NNLO central PDFs, as ratios to CT10W NLO, at Q=85 GeV

PDF induced Correlations of gg H and t t cross sections

CTEQ-TEA NNLO PDF analysis Need to know well Higgs production cross sections, with the combined PDF and α s uncertainties.

LHC collider energy dependence GF VBF

Correlations of Higgs cross sections to PDFs GF strongly correlates to g(x) around x=0.01 @ 125 GeV s VBF g GF u g s

Discriminate Higgs Production Mechanisms Using Jet Energy Profiles Important to measure the couplings of Higgs boson to other SM particles. Need to separate vector boson fusion (VBF) from gluon fusion (GF) production mechanisms for the Higgs boson. Various kinematical distributions look alike after imposing relevant kinematic cuts. Propose to study the final state jet energy profiles to discriminate VBF from GF processes. Hep-ph/1306.0899 V. Rentala, N. Vignaroli, H.-N. Li, Z. Li, CPY

Higgs production mechanisms

SM Higgs @ 14 TeV LHC

Higgs decay branching ratios For 125 GeV Higgs, Total decay width is 4.03 MeV. Br bb = 0.58 Br WW = 0.22 Br gg = 0.086 Br ττ = 0.06 Br cc = 0.028 Br ZZ = 0.027 Br γγ = 0.0023 Br Zγ = 0.0016

Higgs + 2 jets, in di-photon channel Following CMS analysis: Longer tail in GF, due to large M jj cut. P T Peaks around M W In VBF, 2 due to weak boson propagators.

Jet Energy Profiles

pqcd Resummation calculations The perturbative QCD resummation technique is applied to improve prediction on jet energy profile to describe CDF and CMS data. Final state quark jets can be statistically separated from gluon jets by studying their corresponding jet energy profiles. Hep-ph/1107.4535; 1206.1344 H.-N. Li, Z. Li, CPY

Separating Quark from Gluon Jets

For 125 GeV SM Higgs Boson Simulate H+1,2,3 jets events with MadGraph v5 Pass them to Pythia v6.4 for showering and hadronization, and use MLM prescription for matching. Jets are reconstructed using SpartyJet, a wrapper for FastJet, using the anti-k t jet algorithm with R = 0.7

Compare Jet Energy Profiles from Pythia and pqcd The central jet is chosen, for its jet energy profile (JEP) could be better measured than a forward jet.

Our Analyses Pythia predictions depend on the specific tune considered (Pythia tune-a). pqcd resummation predictions, without including power suppressed contribution, do not depend on any non-perturbative physics. Hence, we use pqcd prediction to determine the central value of the JEP, and use Pythia results to estimate the error on the JEP.

Compare various model predictions in JEP Compare SM prediction with two hypothetical cases of a Higgs produced via pure VBF or GF. @14TeV LHC The statistical errors are derived from Madgraph+Pythia simulation.

Event rates and f V at 14 TeV LHC (with 100 1/fb)

Background contamination Assume the (γγjj) background JEP, ψ B r, can be measured from (side-band) data, so that the signal JEP, ψ s r, can be obtained from the observed JEP, ψ obs r. The errors scale by the factor

Background cross sections

Summary on JEP We use (quark vs. gluon) Jet Energy Profile to discriminate the production mechanism of Higgs boson, VBF vs. GF. Similar techniques can be applied to probe New Physics.