Constraining minimal U(1) B L model from dark matter observations

Constraining minimal U(1) B L model from dark matter observations Tanushree Basak Physical Research Laboratory, India 10th PATRAS Workshop on Axions, WIMPs and WISPs CERN Geneva, Switzerland July 3, 2014 Tanushree Basak (PRL) 10th PATRAS Workshop 2014 on Axions, WIMPs and WISPs 1

Motivation Shortcomings of Standard Model Motivation : Shortcomings of Standard Model SM works beautifully, explaining all experimental phenomena to date with great precision No compelling hints for deviations. But many questions remain unanswered: Higgs mass is not protected by any symmetry Hierarchy Problem. SM has 19 unknown parameters whose value are to be set experimentally. No cold dark matter candidate. Neutrinos are massless in SM. Does not explain fermion mass hierarchy. It can not explain baryogenesis and leptogenesis. It does not give the gauge coupling unification at some high scale. Tanushree Basak (PRL) 10th PATRAS Workshop 2014 on Axions, WIMPs and WISPs 2

Motivation Extension of SM Shortcomings of SM = Provides motivation for BSM Physics In Standard Model : NO DM candidate! Tanushree Basak (PRL) 10th PATRAS Workshop 2014 on Axions, WIMPs and WISPs 3

Motivation Extension of SM Shortcomings of SM = Provides motivation for BSM Physics In Standard Model : NO DM candidate! Solution : Extensions of SM to accommodate a DM candidate Tanushree Basak (PRL) 10th PATRAS Workshop 2014 on Axions, WIMPs and WISPs 3

Motivation Extension of SM Shortcomings of SM = Provides motivation for BSM Physics In Standard Model : NO DM candidate! Solution : Extensions of SM to accommodate a DM candidate Some of the possible extensions of SM : Supersymmetric extension (Neutralino, Gravitino...) Gauge singlet scalar extension Fermion singlet and scalar singlet Gauge extension of SM Tanushree Basak (PRL) 10th PATRAS Workshop 2014 on Axions, WIMPs and WISPs 3

Model Gauged Minimal U(1) B L Model Tanushree Basak (PRL) 10th PATRAS Workshop 2014 on Axions, WIMPs and WISPs 4

Framework of the Model Model Particle content of minimal U(1) B L extension (anomaly free) of SM : Particle Q u R d R L e R Φ S N R 1,2 N R 3 SU(2) L 2 1 1 2 1 2 1 1 1 U(1) Y 1/6 2/3-1/3-1 -1 1 0 0 0 U(1) B L 1/3 1/3 1/3-1 -1 0 2-1 -1 Z 2 + + + + + + + + - N. Okada et al. 10; Kanemura et al. 11; T. Basak et al. 14 Additional Z 2 -symmetry imposed : Z 2 charge +1(or even) for all the particles except N 3 R Ensures stability for N 3 R = becomes a viable WIMP - DM candidate Tanushree Basak (PRL) 10th PATRAS Workshop 2014 on Axions, WIMPs and WISPs 5

Model Scalar potential V (Φ, S) = m 2 Φ Φ + µ 2 S 2 +λ 1 (Φ Φ) 2 + λ 2 S 4 +λ 3 Φ Φ S 2 After spontaneous symmetry breaking (SSB) the two scalar fields can be written as, ( ) 0 Φ = v+φ, S = v B L + φ 2 2 with v and v B L real and positive. The mass eigenstates are linear combinations of φ and φ, and written as ( ) ( ) ( ) H1 cos α sin α φ = sin α cos α φ H 2 where, we identify H 2 as the SM-like Higgs boson with mass 125.5 GeV. Tanushree Basak (PRL) 10th PATRAS Workshop 2014 on Axions, WIMPs and WISPs 6

Model Decay Width of Heavy Scalar Boson 100 Γ H (GeV) 10 1 m H (GeV) 300 400 500 600 700 900 0.1 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 cosα Total decay width, Γ H has strong dependence on the mixing angle cos α and mass Tanushree Basak (PRL) 10th PATRAS Workshop 2014 on Axions, WIMPs and WISPs 7

Model Fermionic Part of the model Yukawa part : important for DM interaction and the interaction part is L Y = L SM Y + L int L int = 3 2 β=1 i=1 y i β l β ΦNi 3 i=1 y ni 2 N i R SNi R where, Φ = iτ 2 Φ. DM interacts with the SM particles via Z -boson and h, H. But, Z -boson being heavy (m Z 2.33 TeV) = effectively Higgs-portal Tanushree Basak (PRL) 10th PATRAS Workshop 2014 on Axions, WIMPs and WISPs 8

Neutrino mass generation Model Neutrino mass generated via Type-I seesaw mechanism m νl md T m 1 M m D, m νh m M where, m D = (y j β / 2)v, (j = 1, 2) and m Mi = (y ni / 2)v B L, (i = 1, 2, 3). has no Yukawa coupling with the left-handed lepton doublet the lightest neutrino remains massless. N 3 R Tanushree Basak (PRL) 10th PATRAS Workshop 2014 on Axions, WIMPs and WISPs 9

Dark Matter Observations Dark Matter Observations and Constraints Tanushree Basak (PRL) 10th PATRAS Workshop 2014 on Axions, WIMPs and WISPs 10

Relic Abundance Dark Matter Observations Relic Density Relic density : Ω DM h 2 = 1.1 10 9 g m Pl σv GeV 1 where x f = m N 3 R /T D with T D as decoupling temperature and σv = 1 m 2 N R 3 x f { w(s) 3 ( ) } 1 2w(s) 4m 2 N w (s) 2 R 3 x s=4m 2 N R 3 M. Srednicki et al. 88 w(s) depends on amplitude of different annihilation processes, N 3 RN 3 R b b, τ + τ, W + W, ZZ, and hh w(s) = 1 s 4m 2 final dcos φ 32π s 2 all possible channels M 2 Tanushree Basak (PRL) 10th PATRAS Workshop 2014 on Axions, WIMPs and WISPs 11

Dark Matter Observations Relic Density Typical choice of benchmark values : m h m H Γ h v B L g B L 125 GeV 500 GeV 4.7 10 3 GeV 7 TeV 0.1 Tanushree Basak (PRL) 10th PATRAS Workshop 2014 on Axions, WIMPs and WISPs 12

Dark Matter Observations Relic Density Typical choice of benchmark values : m h m H Γ h v B L g B L 125 GeV 500 GeV 4.7 10 3 GeV 7 TeV 0.1 Variation of w(s) near resonance : w (s) b,τ,w,z (GeV -2 ) 10-3 10-4 10-5 10-6 10-7 10-8 10-9 10-10 (a) cosα = 0.93 Total W + W - Z Z b b τ + τ - 10-11 62 62.2 62.4 62.6 62.8 63 m 3 NR (GeV) w (s) b,w,z,h (GeV -2 ) 10-6 10-7 10-8 10-9 10-10 10-11 (b) cosα = 0.93 Total W + W - Z Z h h b b 10-12 230 235 240 245 250 255 260 265 270 m 3 NR (GeV) Tanushree Basak (PRL) 10th PATRAS Workshop 2014 on Axions, WIMPs and WISPs 12

Dark Matter Observations Relic Density Relic abundance as a function of DM mass 10 3 10 2 cosα 0.45 0.93 m H = 500 GeV 10 Ω CDM h 2 1 10-1 10-2 Ω CDM h 2 = 0.1148 ± 0.0019 10-3 50 70 100 200 250 400 m 3 NR (GeV) Important feature of Higgs-portal DM : Scalar Resonance Relic abundance is found to be consistent with the recent WMAP9 and PLANCK data only near scalar resonances, i.e, m N 3 R = (1/2)m h,h Tanushree Basak (PRL) 10th PATRAS Workshop 2014 on Axions, WIMPs and WISPs 13

Dark Matter Observations Constraints on Parameter space Relic Density Perform scan over the entire parameter space of m H and scalar mixing cos α, consistent with relic abundance cosα 1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 Less Abundance of DM Ω CDM h 2 = 0.1148 ± 0.0019 Over Abundance of DM 300 400 500 600 700 800 900 1000 m H (GeV) Relic abundance near the resonance depends on : scalar mixing angle (α), heavy scalar mass (m H ) and decay width (Γ H ). Tanushree Basak (PRL) 10th PATRAS Workshop 2014 on Axions, WIMPs and WISPs 14

Dark Matter Observations Lagrangian for effective interaction Spin-independent Cross-Section Effective lagrangian for spin-independent interaction : L eff = f p N3 R N 3 R pp + f n N3 R N 3 R nn where, f p,n is the hadronic matrix element. a q f p,n = q=u,d,s f (p,n) m p,n Tq a q + 2 m q 27 f (p,n) TG q=c,b,t a q m p,n m q is the effective coupling constant between DM and the quark. SI-scattering cross section of DM off a nucleon : σ scalar = 4m2 r π f 2 p,n m r is the reduced mass of the nucleon. Tanushree Basak (PRL) 10th PATRAS Workshop 2014 on Axions, WIMPs and WISPs 15

Dark Matter Observations Spin-independent Cross-Section Approximate form of a q The analytical form of a q can be derived as, [ ] a q = y n 3 m q v 1 2 mh 2 1 mh 2 sin α cos α where, y n3 = 2m N 3 R /v B L is the Yukawa coupling. Spin-independent scattering cross-section of DM off a nucleon is maximum for cos α = 0.707, and maximum σ p depends on the value of heavy scalar mass. Tanushree Basak (PRL) 10th PATRAS Workshop 2014 on Axions, WIMPs and WISPs 16

Dark Matter Observations Spin-independent Cross-Section Spin-independent Cross-Section and XENON 100 Limits 10-42 m H (GeV) 300 900 cosα=0.707 σ SI p (cm2 ) 10-44 10-46 LUX (2013) XENON 100 (2012) XENON1T (2017) 10-48 6 10 20 50 70 100 200 500 m NR 3 (GeV) E. Aprile et al. 12; Akerib et al. 13; T. Basak et al. 14 is well below the Xenon100 and LUX exclusion limits for DM mass ranging from 5 500 GeV. σ SI p Tanushree Basak (PRL) 10th PATRAS Workshop 2014 on Axions, WIMPs and WISPs 17

Dark Matter Observations Fermi-LAT upper bound on σv γγ Fermi-LAT upper bound on σv γγ The RH-neutrino dark matter NR 3 can also annihilate into two photon final state mediated by scalar bosons (h and H) w(s) γγ for massless final product is defined as, w(s) γγ = 1 M 32π N 3 R NR 3 γγ 2 where, spins spins M N 3 N 3 R R γγ 2 = { y 2 n (s 4m 2 Mh γγ 2 sin 2 α 3 N R 3 ) (m h 2 s)2 + m h 2 + M H γγ 2 cos 2 α Γ2 (m h H 2 s)2 + m H 2 Γ2 H + M h γγ M H γγ sin α cos α{(mh 2 s)(m2 H s) + m } hm H Γ h Γ H } ((m h 2 s)2 + m h 2Γ2 h )((m2 H s)2 + m H 2 Γ2 H ) Tanushree Basak (PRL) 10th PATRAS Workshop 2014 on Axions, WIMPs and WISPs 18

Dark Matter Observations Fermi-LAT upper bound on σv γγ Fermi-LAT upper bound on σv γγ The RH-neutrino dark matter NR 3 can also annihilate into two photon final state mediated by scalar bosons (h and H) w(s) γγ for massless final product is defined as, w(s) γγ = 1 M 32π N 3 R NR 3 γγ 2 where, spins spins M N 3 N 3 R R γγ 2 = { y 2 n (s 4m 2 Mh γγ 2 sin 2 α 3 N R 3 ) (m h 2 s)2 + m h 2 + M H γγ 2 cos 2 α Γ2 (m h H 2 s)2 + m H 2 Γ2 H + M h γγ M H γγ sin α cos α{(mh 2 s)(m2 H s) + m } hm H Γ h Γ H } ((m h 2 s)2 + m h 2Γ2 h )((m2 H s)2 + m H 2 Γ2 H ) Caution : Monochromatic γ-ray line!!! The gamma-ray continuum spectra produced due to W + W, ZZ final state supersaturate the 130 GeV monochromatic γ-ray line feature. Tanushree Basak (PRL) 10th PATRAS Workshop 2014 on Axions, WIMPs and WISPs 18

Dark Matter Observations Fermi-LAT upper bound on σv γγ <σv γγ > (cm 3 s -1 ) 1e-26 1e-27 1e-28 1e-29 1e-30 1e-31 1e-32 Fermi-LAT (NFW) Fermi-LAT (Einasto) m H (GeV), cosα 500, 0.935 390, 0.885 1e-33 1e-34 40 60 80 100 120 140 m 3 NR (GeV) 160 180 200 Ackerman et al. 12; T. Basak et al. 14 Clear coincidence between theoretical plots and Fermi-LAT data near resonance point where, m N 3 R (1/2) m h. Tanushree Basak (PRL) 10th PATRAS Workshop 2014 on Axions, WIMPs and WISPs 19

Summary Summary We adopt the minimal U(1) B L extension of SM with an additional Z 2 -symmetry imposed. One of the right-handed neutrino, being odd uder Z 2, qualified as the DM candidate. Relic abundance of the DM is found to be consistent with the latest WMAP9 and Planck data only near scalar resonances. SI-scattering cross-section is well below the Xenon100 and LUX exclusion limits for DM mass ranging from 5 500 GeV. Neutrino mass can be generated in this kind of model via Type-I seesaw mechanism. Tanushree Basak (PRL) 10th PATRAS Workshop 2014 on Axions, WIMPs and WISPs 20

Summary Summary We adopt the minimal U(1) B L extension of SM with an additional Z 2 -symmetry imposed. One of the right-handed neutrino, being odd uder Z 2, qualified as the DM candidate. Relic abundance of the DM is found to be consistent with the latest WMAP9 and Planck data only near scalar resonances. SI-scattering cross-section is well below the Xenon100 and LUX exclusion limits for DM mass ranging from 5 500 GeV. Neutrino mass can be generated in this kind of model via Type-I seesaw mechanism. Thank you Tanushree Basak (PRL) 10th PATRAS Workshop 2014 on Axions, WIMPs and WISPs 20