Dynamics of a two-step Electroweak Phase Transition in - PowerPoint PPT Presentation

Dynamics of a two-step Electroweak Phase Transition in Collaboration with Pavel Fileviez Pérez May 2, 2014 Michael J. Ramsey-Musolf Kai Wang ACFI Higgs Portal Workshop Hiren Patel hiren.patel@mpi-hd.mpg.de

Electroweak Baryogenesis and Sakharov’s Criteria Generation of particle/ Generation of baryon First order electroweak C, B e - β ˆ H antiparticle asymmetry asymmetry phase transition CP via bubble nucleation baryons captured, B+L-violating EW Sphalerons convert and preserved. baryons back to anti-leptons. “EW Sphaleron” Thermal jumps Sphaleron proc. must be quenched! 0 1 Hiren Patel 2

Electroweak Baryogenesis and Sakharov’s Criteria This talk (outline) : Kinetic theory: sphaleron set C, CP-violation aside rate related to its mass Generation of particle/ Generation of baryon First order electroweak C, B e - β ˆ 1. New Strategy to H (energy) antiparticle asymmetry asymmetry phase transition CP strengthen phase transition Two-step phase transition H.Patel, M.J. Ramsey-Musolf, Sphaleron mass PRD 88 (2013), 035013 dependent on Higgs field value inside bubble Connection to colliders via bubble nucleation P . Fileviez Pérez, H.Patel, At phase transition, need M.J. Ramsey-Musolf, K. Wang. ratio to be large. PRD 79 (2009), 055024 baryons captured, B+L-violating EW Sphalerons convert and preserved. baryons back to anti-leptons. 2. Gauge dependence ? “EW Problem: Sphaleron” Baryon number Thermal This is gauge dependent preservation criterion on jumps Sphaleron proc. must strength of phase H.Patel, M.J. Ramsey-Musolf, be quenched! transition. JHEP 1107 (2011), 029 0 1 Hiren Patel 3

Previous Strategies (to strengthen phase transition) Central quantity of interest: Effective Potential Condition from requiring quenched sphalerons: related to model > parameters Tune parameters , or add new fields (DoF) to model to: Make bigger. Make smaller. In general, very difficult. Hiren Patel 4

Previous Strategies (to strengthen phase transition) Extend model with extra scalar degrees of freedom. Effective potential a function of multiple order parameters. In regions of parameter space, structure of free energy is such that there could be a multi-step phase transition. If extra degrees of freedom are SM-gauge singlets, step 2 EW sphaleron not affected in essential way, � Condition on phase transition strength step 1 ? Applied only on final step. Hiren Patel 5

If extra scalar degrees of freedom carry gauge quantum numbers, Sphalerons would couple to scalar field, phase transitions induced by these could influence them. (model-builder’s POV) In this setup, it may be easier to generate a strong first order phase transition at step 1. underlying parameters controlling this step step 2 are largely unconstrained. (but possibly measured at LHC) step 1 Hiren Patel 6

SM — Formulation P . Fileviez Pérez, H.Patel, M.J. Ramsey-Musolf, K. Wang. PRD 79 (2009), 055024 Scalar Field Content: Higgs doublet SU(2) real triplet 2 3 Couplings: (renormalizable) Fermiophobic — incompatible hypercharge Gauge-couplings: couples to W, Z and EM field Scalar potential: new particle Higgs portal interaction mass + self coupling Standard model Four unmeasured parameters Hiren Patel 7

Phenomenological Constraints In general, potential permits VEV s for both and . Triplet VEV contributes to W mass (but not Z) W mass Z mass SM relation: weak charged and neutral current rates upset SM (L.O.) SM Experimentally, SM relation satisfied to high prec. Translates to bound: (95% conf.) Hiren Patel 8

Phenomenological Constraints Experimentally, SM relation satisfied to high prec. Translates to bound: (95% conf.) Easy and natural explanation of smallness: depends linearly on (for small values): (1% EW scale) Technically natural, but make simplifying assumption: Three unmeasured parameters Potential is now SO(3) symmetric and has Hiren Patel 9

Particle Spectrum Three new scalar states (97%) (LEP) ( 3%) (stable) Fix EW radiative corrections split degeneracy (LHC) Cirelli, Fornengo, Strumia … arXiv:0706.4071 (hep-ph) Hiren Patel 10

Zero-temperature Vacuum Structure H.Patel, M.J. Ramsey-Musolf, PRD 88 (2013), 035013 Pattern of phase transition influenced by zero-T vacuum structure 2.0 Region B Region A 1.5 A 1.0 B metastable 0.5 vacuum EW vacuum Electroweak Electroweak metastable vacuum 0.0 vacuum 100 120 140 160 180 200 Step 2 Step 1 model potential one step Finite temperature: Baryon asymmetry generation in first step Hiren Patel 11

’t Hooft—Polyakov Monopoles Peculiar feature: Sigma phase resembles Glashow-Salam model of EW interactions (no weak-neutral currents) ’t Hooft and Polyakov showed stable magnetic monopole solution . => early universe populated by monopoles => subsequently wiped out after 2nd phase transition to EW phase. Rubakov effect: scattering with Fermions violates B+L exactly like sphalerons . In addition to sphaleron processes, monopoles would also wipeout baryon asymmetry But to what extent? Depends on monopole concentration: 1. Kibble mechanism equil. monopole ( ) 2. Thermal production ( Dominant ) number density (monopole-antimonopole pair-production) Bigger Higher mass Lower concentration Hiren Patel 12

Baryon preservation Step 2 Step 1 model potential Step 1: - Sphalerons rates suppressed - Monopole density suppressed stronger Step 1 greater suppression 2.0 Qualitatively: (gauge-dep) Step 1 0.44 1.2 1.5 0.50 Smaller leads to stronger transition: 0.56 1.0 0.62 4.0 0.68 0.5 Step 2: 0.74 - SM EW Klinkhamer-Manton 0.0 Sphalerons rates suppressed 100 120 140 160 180 200 always sufficiently strong Hiren Patel 13

Modified Higgs Decay model potential Currently, most sensitive to Higgs-portal coupling adds new contribution to amplitude 200 0% —10% —20% 180 +10% 160 —30% 140 +20% —40% 120 100 80 1.0 0.5 0.0 0.5 1.0 1.5 2.0 Hiren Patel 14

Modified Higgs Decay model potential Currently, most sensitive to Higgs-portal coupling adds new contribution to amplitude 200 0% —10% April 2014 —20% 180 +10% 160 (stat) σ ATLAS Total uncertainty —30% (sys) σ 1 on m = 125.5 GeV ± σ µ 140 H +20% (theo) σ 0 1 2 3 —40% 0.23 ± H → γ γ 120 0.21 ± + 0.33 = 1.55 µ 0.15 ± - 0.28 100 + 0.5 Low p = 1.6 µ 0.3 ± Tt - 0.4 + 0.7 High p 80 = 1.7 µ 0.5 ± Tt 0.6 - 2 jet high + 0.8 = 1.9 µ 0.6 ± mass (VBF) 0.6 - 1.0 0.5 0.0 0.5 1.0 1.5 2.0 + 1.2 = 1.3 µ VH categories 0.9 ± - 1.1 Hiren Patel 15 0.33 ± H ZZ* 4l

LHC Production: Potential has Z 2 symmetry: model potential associated production of . Distinctive LHC signature 2 charged tracks 1 charged track missing missing Production cross section: Hiren Patel 16

as a CDM candidate model potential M. Cirelli, A. Strumia, M. Tamburini. Annihilation channels: Nucl. Phys. B787 , 152 (2007) no resum 0.2 Relic Abundance 0.15 observed abundance Sommerfeld resum. 0.1 0.05 Dark matter saturation 0 at 2.7 TeV 0 0.5 1 1.5 2 2.5 3 3.5 14 TeV LHC: production Hiren Patel 17

This talk (outline) : Kinetic theory: sphaleron set C, CP-violation aside rate related to its mass 1. New Strategy to (energy) strengthen phase transition Two-step phase transition H.Patel, M.J. Ramsey-Musolf, Sphaleron mass PRD 88 (2013), 035013 dependent on Higgs field value inside bubble Connection to colliders P . Fileviez Pérez, H.Patel, At phase transition, need M.J. Ramsey-Musolf, K. Wang. ratio to be large. PRD 79 (2009), 055024 ? Problem: Baryon number This is gauge dependent preservation criterion on strength of phase H.Patel, M.J. Ramsey-Musolf, transition. JHEP 1107 (2011), 029 Hiren Patel 18

(standard) Computation of 1. Track evolution of minima in In a gauge theory, the effective potential is gauge dependent. as a function of temperature. Standard Model 2. Numerically solve minimization and degeneracy condition equations: 1 2 decreasing temperature 0 50 100 150 200 Computed and depends on gauge parameter Hiren Patel 19

Diagnosis & Resolution I h φ i Determination & 1 of (or ) T c T N T c ~Resolution~ ~Diagnosis~ “h-bar Expansion method” Nielsen gauge- • T c Minimize by an inversion of series identity independent counts # of loops V ( φ , T ) = V 0 + ~ V 1 + ~ 2 V 2 + . . . • valid order-by-order in loop- expansion φ min = φ 0 + ~ φ 1 + ~ 2 φ 2 + . . . � • But, numerical solution to Equation for ea. power of ; yields . minimization condition Subs. into each side; 1. V ( φ min , T ) = V 0 ( φ 0 ) + ~ V 1 ( φ 0 , T ) 2. leads to inconsistent truncation in loop-expansion! Hiren Patel 20