BSM and beta decay...BRs Q-values → phase space How do we ... Gonzalez-Alonso, Naviliat-Cuncic,...
Transcript of BSM and beta decay...BRs Q-values → phase space How do we ... Gonzalez-Alonso, Naviliat-Cuncic,...
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BSM and beta decay
Vincenzo CiriglianoLos Alamos National Laboratory
ACFI Workshop on “Beta decays as a probe of new physics”Amherst, Nov 1-3 2018
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• New physics in beta decays: generalities and EFT framework
• Constraints on non-standard charged current interactions
• global analysis of beta decays
• collider input: LEP, LHC
• comparison of sensitivities
• Summary and outlook
Outline
Special thanks to Martin Gonzalez-Alonso for sharing his slides from the WE-Heraeus-Seminar on “Particle Physics with Cold and UltraCold Neutrons”
October 24-26, 2018, Bad Honnef
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Semileptonic processes: SM and beyond
• In the SM, W exchange ⇒ V-A currents, universality
1/Λ2 GF ~ g2Vij/Mw2 ~1/v2
,τ
WR, H+, leptoquarks, Z’, SUSY,…
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Semileptonic processes: SM and beyond
• In the SM, W exchange ⇒ V-A currents, universality
1/Λ2 GF ~ g2Vij/Mw2 ~1/v2
,τ
WR, H+, leptoquarks, Z’, SUSY,…
• Broad sensitivity to BSM scenarios
• Experimental and theoretical precision at or approaching 0.1% level Probe effective scale Λ in the 5-10 TeV range
SUSY analyses:
Bauman, Erler, Ramsey-Musolf, arXiv:1204.0035,
… Kurylov &
Ramsey-Musolf hep-ph/0109222.
… Hagiwara et
al1995 …
Barbieri et al 1985
…
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Connecting scales — EFTTo connect UV physics to neutron and nuclear beta decays, use EFT
Matching to BSM
scenarios
Perturbative matching within SM
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Connecting scales — EFTTo connect UV physics to neutron and nuclear beta decays, use EFT
Matching to BSM
scenarios
Perturbative matching within SM
Hadronic matrix
elements
Nuclear matrix
elements
Non-perturbative strong interactions
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• New physics effects are encoded in ten quark-level couplings
Effective Lagrangian at E~GeV
• Quark-level version of Lee-Yang effective Lagrangian, allows us to connect nuclear & high energy probes
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• New physics effects are encoded in ten quark-level couplings
Effective Lagrangian at E~GeV
Can interfere with SM: linear sensitivity to εi
Bhattacharya et al., 1110.6448 VC, Graesser, Gonzalez-Alonso 1210.4553
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• New physics effects are encoded in ten quark-level couplings
Effective Lagrangian at E~GeV
Interference with SM suppressed by
mν/E: quadratic sensitivity to εi ~
Can interfere with SM: linear sensitivity to εi
Bhattacharya et al., 1110.6448 VC, Graesser, Gonzalez-Alonso 1210.4553
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• Work to first order in rad. corr. and new physics
Effective Lagrangian at E~GeV
Fermi constant extracted fro muon lifetime, possibly
“contaminated” by new physics
Marciano-Sirlin 1981 Sirlin 1982
SM rad. corr. ⊃ “large log”
(α/π)×Log(MZ/μ)
Note: besides the pre-factor, ϵR appears in nuclear decays in the combination gA ≡ gA × (1- 2ϵR)
_
Bhattacharya et al., 1110.6448 VC, Graesser, Gonzalez-Alonso 1210.4553
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1. Differential decay distribution
Lee-Yang, 1956 Jackson-Treiman-Wyld 1957
Theory input: gV,A,S,T (from lattice QCD) + rad. corr.
a(gA), A(gA) , B(gA, gαεα), … isolated via suitable experimental
asymmetries
How do we probe the εα? (1)
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Nucleon charges from lattice QCDWith estimates of all systematic errors (mq, a, V, excited states)
Bhattacharya et al. 1806.09006
gS
~10%
gT
~5%
gA
1%
Chang et al. (CalLat) 1805.12030
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2. Total decay rates
How do we probe the εα? (2)
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2. Total decay rates
Experimental inputLifetimes,
BRsQ-values →phase space
How do we probe the εα? (2)
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2. Total decay rates
Theory input
Hadronic / nuclear matrix elements
and radiative corrections
Lattice QCD, chiral EFT, dispersion relations, …
How do we probe the εα? (2)
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2. Total decay rates
Channel-dependent effective CKM element
~
How do we probe the εα? (2)
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2. Total decay rates
For nuclei, rate traditionally written in terms of “corrected FT values”
Nucleus-dependent radiative & Isospin Breaking correction
“Inner” radiative correction ΔR V= (2.36 ± 0.04)%
[Marciano-Sirlin 2006]
How do we probe the εα? (2)
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2. Total decay rates
For nuclei, rate traditionally written in terms of “corrected FT values”
Nucleus-dependent radiative & Isospin Breaking correction
“Inner” radiative correction ΔR V= (2.467 ± 0.022)%[Seng et al. 1807.10197]
How do we probe the εα? (2)
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Snapshot of the field
Gonzalez-Alonso, Naviliat-Cuncic, Severijns, 1803.08732 & M. Gonzalez-Alonso slides
• Experimental precision between ~0.01% and few %
Nuclei
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Snapshot of the field• Experimental precision between ~0.01% and few %
“Corrected” FT values
FT values before including nucleus-dependent radiative
correction
Hardy-Towner 1411.5987
Gonzalez-Alonso, Naviliat-Cuncic, Severijns, 1803.08732 & M. Gonzalez-Alonso slides
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Snapshot of the field• Experimental precision between ~0.01% and few %
Gonzalez-Alonso, Naviliat-Cuncic, Severijns, 1803.08732 & M. Gonzalez-Alonso slides
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Results of global fit to low-E dataGonzalez-Alonso, Naviliat-Cuncic, Severijns, 1803.08732
• Standard Model fit (λ= gA/gV)
• Fit driven by Ft’s (0+ →0+) and τn (not An)
λ
Vud (1+ ΔR)1/2
Experimental Radiative corrections (ΔR)
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Results of global fit to low-E dataGonzalez-Alonso, Naviliat-Cuncic, Severijns, 1803.08732
• Standard Model fit (λ= gA/gV)
• Fit driven by Ft’s (0+ →0+) and τn (not An)
λ
Vud (1+ ΔR)1/2
Experimental New Radiative corrections (ΔR)
[Seng et al. 1807.10197]
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Results of global fit to low-E dataGonzalez-Alonso, Naviliat-Cuncic, Severijns, 1803.08732
• Fit including BSM couplings (driven by Ft’s (0+ →0+) , τn, and An)
1st error:experimental
2nd error: ΔR, gA , gS , and gT
~2 % → ~ 0.5% **
~0.2 %
~0.1 %
** CalLat 1805.12030
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Cabibbo universality test
Extraction dominated by 0+→0+ nuclear transitions
Extraction dominated by K decays:
K→πeν & K→μν vs π→μν (Vus/Vud) Hardy-Towner 1411.5987
CKM 2016FLAVIANET report 1005.2323 and refs therein
Lattice QCD input from FLAG 1607.00299 and refs therein + MILC 2018 1809.02827
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Vus from K→ μν
Vus from K→ πlν
ΔCKM = - (4 ± 5)∗10-4 ~ 1σ
ΔCKM = - (12 ± 6)∗10-4 ~ 2σ K→ μν
K→ πlν unitarity0+ →
0+
0.4%
0.02%
Cabibbo universality test
Vus
_
Vud
_
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Vus from K→ μν
Vus from K→ πlν
ΔCKM = - (4 ± 5)∗10-4 ~ 1σ
ΔCKM = - (12 ± 6)∗10-4 ~ 2σ
Hint of something [ε’s ≠0] or SM theory input?
Worth a closer look: at the level of the best LEP EW
precision tests, probing scale Λ~10 TeV
K→ μν
K→ πlν unitarity0+ →
0+
0.4%
0.02%
Cabibbo universality test
Vus
_
Vud
_
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Vus from K→ μν
Vus from K→ πlν
ΔCKM = - (14 ± 4)∗10-4 ~3.5σ
ΔCKM = - (22 ± 5)∗10-4 ~4.5σ
With new radiative corrections[Seng et al. 1807.10197]
K→ μν
K→ πlν unitarity0+ →
0+
0.4%
0.02%
Cabibbo universality test
Vus
_
Vud
_
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Impact of neutrons• Independent extraction of Vud @ 0.02% requires:
δτn ~ 0.35 s δτn/τn ~ 0.04 %
δgA/gA ~0.15% → 0.03% (δa/a , δA/A ~ 0.14%)
UCNτ @ LANL [τn~ 877.7(7)(3)s] is almost there, will reach δτn ~ 0.2 s
δA/A < 0.2% can be reached by PERC, UCNA+δa/a ~ 0.1% at Nab1707.01817
Czarnecki, Marciano, Sirlin
1802.01804
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VC, Gonzalez-Alonso, Jenkins 0908.1754
Interplay with High Energy physics• Need to know high-scale origin of the various εα
Match SM-EFT and SM-EFT’
• Model-independent statements possible in “heavy BSM” scenarios: MBSM > TeV → new physics looks point-like at collider
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VC, Gonzalez-Alonso, Jenkins 0908.1754
Interplay with High Energy physics
Gauge invariance
dj
ui
• Need to know high-scale origin of the various εα
εL,R originate from SU(2)xU(1) invariant vertex corrections
E.g. from WL-WR mixing in Left-Right symmetric models
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VC, Gonzalez-Alonso, Jenkins 0908.1754
Interplay with High Energy physics
…
dj
ui
• Need to know high-scale origin of the various εα
εL,R originate from SU(2)xU(1) invariant vertex corrections
dj
ui
εS,P,T and one contribution to εL arise from SU(2)xU(1) invariant
4-fermion operators
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dj
ui
• Need to know high-scale origin of the various εα
Interplay with High Energy physics
εL,R originate from SU(2)xU(1) invariant vertex corrections
dj
ui
• LEP:
• Strong constraints (<0.1%) on L-handed vertex corrections (Z-pole)
• Weaker constraints on 4-fermion interactions (σhad)
εS,P,T and one contribution to εL arise from SU(2)xU(1) invariant
4-fermion operators
• What about LHC?
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• The effective couplings εα contribute to the process pp → eν + X
• No excess events in transverse mass distribution: bounds on εα
mT(GeV) mT(GeV)
LHC sensitivity: 4-fermionsBhattacharya et al., 1110.6448, VC, Graesser, Gonzalez-Alonso 1210.4553
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LHC sensitivity: vertex corrections
• Vertex corrections inducing εL,R in the SM-EFT involve the Higgs field (due to SU(2) gauge invariance)
• Can be probed at the LHC by associated Higgs + W production
εL,R εL,R
H
W
Wq
q’
S. Alioli, VC, W. Dekens, J. de Vries, E. Mereghetti 1703.04751
εL
εR
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S. Alioli, VC, W. Dekens, J. de Vries, E. Mereghetti 1703.04751
Z pole
Example 1: εL and εR couplings
ΔCKM ∝ εL+εR
δΓ(π→μν) ∝ εL − εR [fπ from LQCD]
Constraint on εR uses gA =1.271(13)
(CalLat 1805.12030)
Neutron decay: λ = gA (1 − 2 εR)
Z-pole → εL(v)
Falkowski et al 1706.03783
Z pole
(Run 2 projection)
εL
εR
90%CL, assumes only two operators at high scale
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S. Alioli, VC, W. Dekens, J. de Vries, E. Mereghetti 1703.04751
Z pole
Example 1: εL and εR couplings
ΔCKM ∝ εL+εR
δΓ(π→μν) ∝ εL − εR [fπ from LQCD]
Constraint on εR uses gA =1.271(13)
(CalLat 1805.12030)
Neutron decay: λ = gA (1 − 2 εR)
Z-pole → εL(v)
Falkowski et al 1706.03783
Z pole
(Run 2 projection)
εL
εR
90%CL, assumes only two operators at high scale Several lessons:
• Beta decays can be quite competitive with collider
• Connection between CC and NC (gauge invariance!)
• Caveat: going beyond a 2-operator analysis relaxes some of these constraints (but not the one on εR from λ)
• All in all, beta decays provide independent competitive constraints in a global analysis
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Example 2: εS and εT couplings
εS,T @ μ= 2 GeV (MS-bar)
CURRENTεS,T @ μ= 2 GeV (MS-bar)
LHC 36fb-1 @ 13 TeV
Bhattacharya et al 1806.09006
gS =1.01(10)gT =0.99(4)
Bhattacharya et al (PNDME) 1806.09006
Gonzalez-Alonso, Naviliat-Cuncic,
Severijns, 1803.08732
Current low-E data:dominated by
0+→ 0+, τ(n), A(n)
-1.0×10-3 < gS εS < 3.2×10-3
0+ →0+ (bF)Towner-Hardyl, 2010
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Example 2: εS and εT couplings
εS,T @ μ= 2 GeV (MS-bar)
FUTURE
b (n) @ 0.001
b (6He) @ 0.001
LHC puts very strong constraints on 4-fermion interactions
Prospective beta decay measurements competitive, probing ΛS,T ~ 5-10 TeV
gS =1.01(10)gT =0.99(4)
Bhattacharya et al (PNDME) 1806.09006
LHC 36fb-1 @ 13 TeV
Bhattacharya et al 1806.09006
Gonzalez-Alonso, Naviliat-Cuncic,
Severijns, 1803.08732
Current low-E data:dominated by
0+→ 0+, τ(n), A(n)
-1.0×10-3 < gS εS < 3.2×10-3
0+ →0+ (bF)Towner-Hardyl, 2010
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Beta decays in specific models
• Qualitative picture:
WR
H+
u e
d νLQ
“DNA matrix”
...YOUR FAVORITE MODEL
...
Can be made quantitative,
including LHC constraints on
each model
• Beta decays can play very useful diagnosing role
• Model → set overall size and pattern of effective couplings
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Summary
• β decays with sufficient th. and expt. precision (< 0.1%) remain a very competitive probe of new physics
• Discovery potential depends on the underlying model. However, for heavy mediators, EFT shows that a discovery window exists well into the LHC era (simple examples: εL-εR and εS-εT plots)
• Beta decays play unique role in probing vertex corrections εL-εR (not enough precision at the LHC)
• Beta decays can be competitive probes of scalar and tensor interactions if precision reaches < 0.1%
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• The next frontier in beta decays will likely include
• Experiment:
• δτn ~ 0.1s
• <0.1% precision in decay correlation coefficients
• Theory:
• gA at sub-percent level from LQCD
• Radiative corrections: improved data for dispersive method and lattice QCD analysis
Outlook
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Backup
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Summary table
• This table summarizes a large number of measurements and th. input
• Already quite impressive. Effective scales in the range Λ= 1-10 TeV (ΛSM ≈ 0.2 TeV)
VC, S.Gardner, B.Holstein 1303.6953 Gonzalez-Alonso & Naviliat-Cuncic 1304.1759
Gonzalez-Alonso, Naviliat-Cuncic, Severijns, 1803.08732
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• Helicity suppressed in the SM (V-A)π-
• Predicted very precisely in the SM (0.01%): Rπ = 1.2352(1) ×10-4
• Experiment: Rπ = 1.2300(40) ×10-4 will go down to 0.05% level
• This ratio probes a whole set of εP couplings (ν flavor not observed)
Marciano-Sirlin 93 VC-Rosell ’07
TRIUMF and PSI
α=e, μβ=e,μ,τ
Rπ = Γ(π→eν[γ] )/Γ(π→μν[γ])
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• Neglecting non-enhanced εL-εR terms:
• No constraint if
• Assume all εP of similar size (neglect me/mμ)
• Allowed region is an annulus of thickness 1.38 ×10-6
• Marginalize wrt εPex
me/B0
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• Constraint on εS,T via EW radiative corrections: P operator, generated at high scale Λ, induces S and T operators at low scale μ
P S,T
∝
• With log(Λ/μ) ~10, |εS| < 8 ×10-2 and |εT| < 10-3
Voloshin ’92 Campbell-Maybury ’05 Herczeg 95
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Standard Model analysis
• εα=0 and take Vud from 0+ → 0+:
• UCN lifetime and post-2002 gA consistent with SM (blue line) ⇒
• “favored values” within the SM
• if confirmed, will put tightest constraints on BSM interactions
Trap
Post 2002
Pre 2002
Beam
Czarnecki, Marciano, Sirlin 1802.01804
42
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Standard Model analysis
• εα=0 and take Vud from 0+ → 0+:
Czarnecki, Marciano, Sirlin 1802.01804
43
1.255 1.260 1.265 1.270 1.275 1.280 1.285870
875
880
885
890
895 Impact of ϵR = 0.003
Trap
Post 2002
Pre 2002
Beam • UCN lifetime and post-2002 gA consistent with SM (blue line) ⇒
• “favored values” within the SM
• if confirmed, will put tightest constraints on BSM interactions
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Status of scalar and tensor charges
Martin Gonzalez-Alonso
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• Vud from 0+→ 0+ nuclear β decays
Nucleus-dependent rad. corr.
(Z, Emax ,nuclear structure)
Sirlin-Zucchini ‘86 Jaus-Rasche ‘87
Coulomb distortion of wave-functions
Towner-Hardy Ormand-Brown
Ab initio methods?
Vud from 0+ → 0+ nuclear decays
Nucleus-independent short distance rad. corr.
Marciano-Sirlin ‘06
Further improvements with dispersion relations, Lattice QCD?
ΔR =2.36(4)%
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Z of daughter nucleus
Z of daughter nucleus
Vud = 0.97417 (21)
• Vud from 0+→ 0+ nuclear β decays
Vud from 0+ → 0+ nuclear decays
Hardy-Towner 1411.5987
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K→ μν vs π→ μν K→ πlν
Vus from K decays
@ 0.25%@ 0.34%
• Lattice QCD calculations (summaries from FLAG 2016)
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K→ πlν
Vus from K decays
• Lattice QCD calculations
mπ → mπphys, a → 0, dynamical charm
FK/Fπ = 1.1960(25) [stable]Vus / Vud = 0.2313(7)
f+K→π(0)= 0.959(5) → 0.970(3)Vus = 0.2254(13) → 0.2231(9)
FLAG 2016 1607.00299 and refs therein
• Radiative corrections computed to O(e2p2) in ChPT
• World data: FLAVIANET report 1005.2323 and refs therein
K→ μν vs π→ μν
VC, H. Neufeld 1107.6001 VC, M. Giannotti, H. Neufeld 0807.4507