Beyond the Standard Model: Where do we go from here? Marie-Helene Genest, Howard E. Haber, and James Olsen 30 August 2018
�� ������������ �� � �� �� ����� �������������������� A Theorist’s perspective 1. Has the idea of naturalness run its course? Based on an image from the BackReaction Blog of Sabine Hossenfelder
1939: Scalar fields portend an energy scale associated with new phenomena that are close at hand.
Weisskopf’s arguments imply that there should be new physics at the scale of m H /g ∼ 1 TeV. But where is the new TeV-scale physics?
ATLAS Preliminary ATLAS SUSY Searches* - 95% CL Lower Limits √ s = 7, 8, 13 TeV July 2018 E miss √ s = 7, 8 TeV √ s = 13 TeV e , µ, τ , γ Jets � L dt [fb − 1 ] Model Mass limit Reference T χ 0 χ 0 q → q ˜ 0 2-6 jets 36.1 q q ˜ ˜ [2 × , 8 × Degen.] [2 × , 8 × Degen.] 0.9 1.55 m( ˜ q ˜ ˜ q , ˜ Yes 1 ) < 100 GeV 1712.02332 1 χ 0 mono-jet 1-3 jets 36.1 q q ˜ ˜ [1 × , 8 × Degen.] [1 × , 8 × Degen.] 0.43 0.71 q )-m( ˜ Yes m( ˜ 1 ) = 5 GeV 1711.03301 Inclusive Searches χ 0 χ 0 q ˜ 0 2-6 jets Yes 36.1 g ˜ 2.0 m( ˜ g ˜ ˜ g , ˜ g → q ¯ 1 ) < 200 GeV 1712.02332 1 χ 0 g ˜ g ˜ Forbidden 0.95-1.6 m( ˜ 1 ) = 900 GeV 1712.02332 χ 0 - χ 0 q ( ℓℓ )˜ 3 e , µ 4 jets 36.1 g ˜ 1.85 m( ˜ 1706.03731 g ˜ ˜ g , ˜ g → q ¯ 1 ) < 800 GeV 1 ee , µµ χ 0 2 jets Yes 36.1 g ˜ 1.2 g )-m( ˜ 1805.11381 m( ˜ 1 ) = 50 GeV χ 0 χ 0 g → qqWZ ˜ 0 7-11 jets Yes 36.1 ˜ g 1.8 m( ˜ 1708.02794 g ˜ ˜ g , ˜ 1 ) < 400 GeV 1 3 e , µ 4 jets - χ 0 36.1 g ˜ 0.98 g )-m( ˜ 1706.03731 m( ˜ 1 ) = 200 GeV χ 0 0-1 e , µ χ 0 g → t ¯ t ˜ 3 b Yes 36.1 g ˜ 2.0 m( ˜ 1711.01901 g ˜ ˜ g , ˜ 1 ) < 200 GeV 1 3 e , µ 4 jets - χ 0 36.1 ˜ g 1.25 g )-m( ˜ 1706.03731 m( ˜ 1 ) = 300 GeV χ 0 χ 0 χ 0 b 1 ˜ ˜ b 1 , ˜ b 1 → b ˜ 1 / t ˜ χ ± Multiple 36.1 ˜ ˜ Forbidden 0.9 m( ˜ 1 ) = 300 GeV, BR( b ˜ 1708.09266, 1711.03301 b 1 b 1 1 ) = 1 1 χ 0 χ 0 Multiple 36.1 ˜ ˜ Forbidden 0.58-0.82 m( ˜ 1 ) = 300 GeV, BR( b ˜ 1 ) = BR( t ˜ χ ± b 1 b 1 1 ) = 0.5 1708.09266 χ 0 Multiple 36.1 ˜ ˜ Forbidden 0.7 m( ˜ 1 ) = 200 GeV, m( ˜ χ ± 1 ) = 300 GeV, BR( t ˜ χ ± b 1 b 1 1 ) = 1 1706.03731 b 1 ˜ ˜ χ 0 b 1 , ˜ t 1 ˜ t 1 , M 2 = 2 × M 1 Multiple 36.1 ˜ 0.7 m( ˜ 1709.04183, 1711.11520, 1708.03247 t 1 1 ) = 60 GeV 3 rd gen. squarks direct production χ 0 Multiple 36.1 ˜ t 1 ˜ t 1 Forbidden 0.9 m( ˜ 1709.04183, 1711.11520, 1708.03247 1 ) = 200 GeV χ 0 χ 0 0-2 e , µ χ 0 t 1 ˜ ˜ t 1 , ˜ t 1 → Wb ˜ 1 or t ˜ 0-2 jets/1-2 b Yes 36.1 ˜ t 1 1.0 m( ˜ 1506.08616, 1709.04183, 1711.11520 1 )=1 GeV 1 t 1 , ˜ Multiple χ 0 χ 0 t 1 ˜ ˜ H LSP 36.1 t 1 ˜ t 1 ˜ 0.4-0.9 m( ˜ 1 ) = 150 GeV, m( ˜ χ ± 1 )-m( ˜ 1 ) = 5 GeV, ˜ t 1 ≈ ˜ 1709.04183, 1711.11520 t L Multiple ˜ ˜ χ 0 χ ± χ 0 36.1 t 1 t 1 Forbidden 0.6-0.8 m( ˜ 1 ) = 300 GeV, m( ˜ 1 )-m( ˜ 1 ) = 5 GeV, ˜ t 1 ≈ ˜ 1709.04183, 1711.11520 t L t 1 ˜ ˜ t 1 , Well-Tempered LSP Multiple ˜ ˜ χ 0 χ ± χ 0 36.1 t 1 t 1 0.48-0.84 m( ˜ 1 ) = 150 GeV, m( ˜ 1 )-m( ˜ 1 ) = 5 GeV, ˜ t 1 ≈ ˜ 1709.04183, 1711.11520 t L χ 0 χ 0 t 1 → c ˜ c → c ˜ ˜ χ 0 t 1 ˜ ˜ t 1 , ˜ 0 2 c Yes 36.1 t 1 0.85 m( ˜ 1805.01649 1 / ˜ c ˜ c , ˜ 1 ) = 0 GeV 1 ˜ χ 0 t 1 0.46 m( ˜ c )-m( ˜ 1805.01649 t 1 , ˜ 1 ) = 50 GeV mono-jet ˜ χ 0 0 Yes 36.1 t 1 0.43 m( ˜ c )-m( ˜ 1711.03301 t 1 , ˜ 1 ) = 5 GeV t 2 ˜ ˜ t 2 , ˜ t 2 → ˜ 1-2 e , µ ˜ m( ˜ χ 0 t 1 )-m( ˜ χ 0 t 1 + h 4 b Yes 36.1 t 2 0.32-0.88 1 ) = 0 GeV, m( ˜ 1 ) = 180 GeV 1706.03986 χ 0 χ ± χ ± 2-3 e , µ - χ 0 χ 0 ˜ 1 ˜ Yes 36.1 ˜ 1 / ˜ 0.6 m( ˜ 1403.5294, 1806.02293 2 via WZ 1 ) = 0 2 χ ± ee , µµ χ 0 χ 0 ≥ 1 Yes 36.1 ˜ 1 / ˜ 0.17 m( ˜ χ ± 1 )-m( ˜ 1712.08119 1 ) = 10 GeV 2 χ 0 χ ± χ 0 χ ± ℓℓ / ℓγγ / ℓ bb - ˜ 1 / ˜ χ 0 ˜ 1 ˜ Yes 20.3 0.26 m( ˜ 1501.07110 2 via Wh 1 ) = 0 2 χ 0 χ 0 χ ± χ 0 χ ± χ ∓ χ + - ˜ 1 / ˜ χ 0 χ ± χ 0 ˜ 1 ˜ 1 / ˜ 2 , ˜ ν ) , ˜ 2 τ Yes 36.1 0.76 m( ˜ ν )=0.5(m( ˜ 1 )+m( ˜ 1708.07875 direct 1 → ˜ τν ( τ ˜ 2 → ˜ ττ ( ν ˜ ν ) 1 ) = 0, m( ˜ τ , ˜ 1 )) 2 EW χ ± χ 0 ˜ 1 / ˜ χ ± χ 0 χ ± χ 0 0.22 m( ˜ 1 )-m( ˜ ν )=0.5(m( ˜ 1 )+m( ˜ 1708.07875 1 ) = 100 GeV, m( ˜ τ , ˜ 1 )) 2 χ 0 ℓ L , R ˜ ˜ ℓ L , R , ˜ ℓ → ℓ ˜ 2 e , µ χ 0 0 Yes 36.1 ˜ 0.5 m( ˜ 1803.02762 ℓ 1 ) = 0 1 2 e , µ m( ˜ χ 0 ≥ 1 Yes 36.1 ˜ 0.18 ℓ )-m( ˜ 1712.08119 ℓ 1 ) = 5 GeV χ 0 H ˜ ˜ H , ˜ H → h ˜ G / Z ˜ ˜ ˜ BR( ˜ 1 → h ˜ G 0 ≥ 3 b Yes 36.1 0.13-0.23 0.29-0.88 G )=1 1806.04030 H H χ 0 4 e , µ ˜ BR( ˜ 1 → Z ˜ 0 Yes 36.1 0.3 G )=1 1804.03602 H χ − χ ± Direct ˜ χ + 1 ˜ 1 prod., long-lived ˜ χ ± Disapp. trk 1 jet ˜ Yes 36.1 0.46 Pure Wino 1712.02118 1 1 χ ± Long-lived ˜ 0.15 Pure Higgsino ATL-PHYS-PUB-2017-019 particles 1 Stable ˜ g R-hadron - - SMP 3.2 ˜ g 1.6 1606.05129 χ 0 g → qq ˜ Multiple χ 0 Metastable ˜ g R-hadron, ˜ 32.8 ˜ ˜ g g [ τ (˜ [ τ (˜ g ) = 100 ns, 0.2 ns] g ) = 100 ns, 0.2 ns] 1.6 2.4 m( ˜ 1710.04901, 1604.04520 1 ) = 100 GeV 1 χ 0 χ 0 χ 0 GMSB, ˜ 1 → γ ˜ G , long-lived ˜ 2 γ - ˜ χ 0 Yes 20.3 0.44 1 < τ (˜ 1409.5542 1 ) < 3 ns, SPS8 model 1 1 χ 0 g , ˜ displ. ee / e µ/µµ - - 6 < c τ (˜ χ 0 1 ) < 1000 mm, m( ˜ χ 0 g ˜ ˜ 1 → ee ν / e µ ν /µµ ν 20.3 ˜ g 1.3 1 )=1 TeV 1504.05162 LFV pp → ˜ e µ , e τ , µ τ - - λ ′ 311 =0.11, λ 132 / 133 / 233 =0.07 ν τ + X , ˜ ν τ → e µ/ e τ /µ τ 3.2 ˜ ν τ 1.9 1607.08079 χ 0 χ ± χ ± χ 0 χ 0 χ ± χ ∓ 4 e , µ ˜ ˜ 1 / ˜ 1 / ˜ χ 0 ˜ 1 ˜ 1 / ˜ 0 Yes 36.1 0.82 1.33 m( ˜ 1804.03602 2 → WW / Z ℓℓℓℓνν [ λ i 33 � 0 , λ 12 k � 0 ] [ λ i 33 � 0 , λ 12 k � 0 ] 1 ) = 100 GeV 2 2 χ 0 χ 0 χ 0 χ 0 g → qq ˜ 1 , ˜ 4-5 large- R jets - [m (˜ [m (˜ Large λ ′′ 0 36.1 1.3 1.9 1804.03568 g ˜ ˜ g , ˜ 1 → qqq ˜ g g ˜ 1 )=200 GeV, 1100 GeV] 1 )=200 GeV, 1100 GeV] 112 Multiple ˜ g g ˜ [ λ ′′ [ λ ′′ 112 =2e-4, 2e-5] 112 =2e-4, 2e-5] χ 0 RPV 36.1 1.05 2.0 m (˜ ATLAS-CONF-2018-003 1 )=200 GeV, bino-like χ 0 χ 0 t ˜ 1 , ˜ Multiple ˜ g ˜ g [ λ ′′ [ λ ′′ 323 =1, 1e-2] 323 =1, 1e-2] χ 0 g , ˜ g → tbs / ˜ g → t ¯ 36.1 1.8 2.1 m (˜ ATLAS-CONF-2018-003 g ˜ ˜ 1 → tbs 1 )=200 GeV, bino-like χ 0 χ 0 t → t ˜ 1 , ˜ Multiple g ˜ ˜ g [ λ ′′ [ λ ′′ 323 =2e-4, 1e-2] 323 =2e-4, 1e-2] χ 0 t ˜ ˜ t , ˜ 36.1 0.55 1.05 m (˜ ATLAS-CONF-2018-003 1 → tbs 1 )=200 GeV, bino-like t 1 ˜ ˜ t 1 , ˜ 2 jets + 2 b - ˜ ˜ t 1 → bs 0 36.7 t 1 t 1 [ qq , bs ] [ qq , bs ] 0.42 0.61 1710.07171 t 1 ˜ ˜ t 1 , ˜ 2 e , µ - ˜ BR( ˜ t 1 → b ℓ 2 b 36.1 t 1 0.4-1.45 t 1 → be / b µ ) > 20% 1710.05544 10 − 1 1 *Only a selection of the available mass limits on new states or Mass scale [TeV] phenomena is shown. Many of the limits are based on simplified models, c.f. refs. for the assumptions made.
At what point do you lose interest in extending the new physics searches? Ø Keep in mind that after Run 2, you will only have collected 5% of the total luminosity expected during the LHC lifetime. Ø If you discover new physics consistent with explanations of the gauge hierarchy problem (why is m W /M PL ∼ 10 -17 ?), the little hierarchy problem becomes much less pressing.
Final thoughts on naturalness Ø The announcement of the death of naturalness may be premature. Ø There is still room for theoretical innovations. Ø However, in evaluating new approaches to naturalness, it is important to consider how one could test these ideas experimentally (i.e. what observable phenomenon would convince you that Nature has employed a natural theory for the dynamics of electroweak symmetry breaking?).
2. Do we really know the particle content of the TeV-scale effective theory? Ø The fermion sector of the Standard Model (SM) is non-minimal. Three generations—who ordered that? Ø The scalar sector of the SM has a single Higgs boson. Why not multiple families of Higgs scalars? Ø There are good reasons to think that the number of families of chiral fermions is limited to 3. But what about vector-like quarks and leptons? Ø Flavor anomalies have revived interest in leptoquarks.
Ø Are we really sure that the gauge group of the effective TeV-scale theory is SU(3)xSU(2)xU(1)? Are there new gauge bosons lurking in the region of 1—10 TeV? Ø Of course, don’t forget about the dark sector, which I shall define as particles that are neutral with respect to SU(3)xSU(2)xU(1). Perhaps motivated by theories of dark matter, but could exist independently. Communications with the SM sector is possible through the various portals. The Higgs portal ( ! † ! is a SM singlet) § U(1) gauge boson mixing (F "# Fʹ "# ) § The neutrino portal (L† ! N) §
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