Unraveling Flavour Anomalies with Leptoquarks
Explaining the Flavour Anomalies with
the Pati-Salam Leptoquark
Andreas Crivellin
PSI (LTP) & UZH
La Thuile, 25.03.2019
•
Introduction: Leptoquark and the Flavour
anomalies
•
The Pati-Salam Leptoquark
b→s
ττ
enhancement and loop effects
b
→s
l
+
l
-
•
Importance of Loop Effects
•
Possible UV completions
•
QCD corrections to semileptonic B decays
•
Conclusions
Outline
Page 2
Andreas Crivellin
Hints for New Physics
Page 3
Andreas Crivellin
Leptoquark effects
•
b
→c
τν
•
Tree-level effects in semi-leptonic decays
•
Loop-suppressed effects in other flavour
observables like b→s
γ
and
Δ
F=2 processes which
agree with the SM predictions.
•
b→s
μμ
Vector Leptoquark SU(2) Singlet
•
Left-handed effect in b
→s
μμ
•
Left-handed vector current in R(D) and R(D*)
•
No effect in b
→s
νν
•
No proton decay
•
Contained within the Pati-Salam model
•
Massive vector bosons
Non-renormalizable without Higgs mechanism
Pati Salam not possible at the Tev scale
because of K
L
→
μ
e
and K
→
πμ
e
Vector LQ Phenomenology
R(D
(
*
)
) and b
→
s
ττ
•
Large couplings to the second generation
Page 7
B. Capdevila, AC, S. Descotes-Genon, L.
Hofer and J. Matias, PRL.120.181802
Important Loop-Effects
•
Explanation of b
→c
τν
requires large b
τ
and s
τ
couplings (follows from SU(2) invariance)
AC, C. Greub, D. Müller,
F. Saturnino, PRL 2018
Important Loop-Effects
•
Explanation of b
→c
τν
requires large b
τ
and s
τ
couplings (follows from SU(2) invariance)
AC, C. Greub, D. Müller,
F. Saturnino, PRL 2018
Perfect agreement with data
Possible UV completions
•
SU(4)×SU(3)’×SU(2)
L
×U(1)
Y
+ Vector-like fermions
L. Di Luzio, A. Greljo, M. Nardecchia, arXiv:1708.08450
•
SU(4)×U(2)
L
×SU(2)
R
+ Vector-like fermions
L. Calibbi, AC, T. Li, arXiv:1709.00692
•
SU(4)
×
SU(4)
×
SU(4)
M. Bordone, C. Cornella, J. Fuentes-Martin, G. Isidori, arXiv:1712.01368
•
SU(4) ×U(2)
L
×SU(2)
R
including scalar LQs and
light right-handed neutrinos
J. Heeck, D. Teresi,
arXiv:
1808.07492
•
SU(8) might even explain ɛ’/ɛ
S. Matsuzaki, K. Nishiwaki and K. Yamamoto,
arXiv:
1806.02312
•
SU(4)×U(2)×SU(2)
R
in RS background
M. Blanke, AC,
arXiv:
1801.07256
Pati-Salam RS Phenomenology
M. Blanke, AC, PRL 2018
QCD corrections to the Matching
Page 13
•
Perform matching
•
Correct for 4-dimensional Fierz identities
Results
Page 14
J. Aebischer, AC, C. Greub, 1811.08907
•
The Pati-Salam L
eptoquark is tailor made to
explain the flavour anomalies
•
Explanation of R(D) and R(D*) requires a generic
flavour structure:
Huge enhancement of b
→s
ττ
Sizable loop effects in b
→sll
and b
→s
νν
•
Explaining R(D) and R(D*) with the Pati-Salam
leptoquark give the right loop effects in b
→sll
•
QCD corrections to the matching make LHC
bounds slightly weaker
Conclusions
Page 15
Andreas Crivellin
Results I
Page 16
•
Operators generated by
vector
leptoquark
•
Operators generated by
scalar
leptoquark
vector operator
scalar operator
vector operator
scalar operator
tensor operator
Leptoquarks play a crucial role in explaining flavour anomalies in particle physics, particularly in semi-leptonic decays and other flavour observables. This presentation delves into the effects, implications, and potential UV completions of leptoquarks within the Pati-Salam model.
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Presentation Transcript
Bildergebnis fr uzh logo WIR SCHAFFEN WISSEN HEUTE F R MORGEN Andreas Crivellin PSI (LTP) & UZH Explaining the Flavour Anomalies with the Pati-Salam Leptoquark La Thuile, 25.03.2019
Outline Introduction: Leptoquark and the Flavour anomalies The Pati-Salam Leptoquark b s enhancement and loop effects b sl+l- Importance of Loop Effects Possible UV completions QCD corrections to semileptonic B decays Conclusions Page 2 Andreas Crivellin
Bildergebnis fr uzh logo Hints for New Physics Electron channels: SM-like K >2 b s >5 Lepton Flavour Universality Violation (LFUV) b d b u 1-2 a >3 b c >3 Andreas Crivellin Page 3
Leptoquark effects b c b s V V LQ LQ c s b b Tree-level effects in semi-leptonic decays Loop-suppressed effects in other flavour observables like b s and F=2 processes which agree with the SM predictions. Leptoquarks are tailor-made to explain the flavour anomalies
Bildergebnis fr uzh logo Vector Leptoquark SU(2) Singlet Left-handed effect in b s Left-handed vector current in R(D) and R(D*) No effect in b s No proton decay Contained within the Pati-Salam model Massive vector bosons Non-renormalizable without Higgs mechanism Pati Salam not possible at the Tev scale because of KL e and K e Good solution, but difficult UV completion
Vector LQ Phenomenology Compatible with constraints for generic couplings
Bildergebnis fr uzh logo R(D(*)) and b s Large couplings to the second generation b s very strongly enhanced B. Capdevila, AC, S. Descotes-Genon, L. Hofer and J. Matias, PRL.120.181802 Page 7
Important Loop-Effects Explanation of b c requires large b and s couplings (follows from SU(2) invariance) AC, C. Greub, D. M ller, F. Saturnino, PRL 2018 Large loop effects in b s
Bildergebnis fr uzh logo Important Loop-Effects Explanation of b c requires large b and s couplings (follows from SU(2) invariance) AC, C. Greub, D. M ller, F. Saturnino, PRL 2018 Large loop effects in b s
Perfect agreement with data Pati-Salam LQ can explain the flavour anomalies
Bildergebnis fr uzh logo Possible UV completions SU(4) SU(3) SU(2)L U(1)Y + Vector-like fermions L. Di Luzio, A. Greljo, M. Nardecchia, arXiv:1708.08450 SU(4) U(2)L SU(2)R + Vector-like fermions L. Calibbi, AC, T. Li, arXiv:1709.00692 SU(4) SU(4) SU(4) M. Bordone, C. Cornella, J. Fuentes-Martin, G. Isidori, arXiv:1712.01368 SU(4) U(2)L SU(2)R including scalar LQs and light right-handed neutrinos J. Heeck, D. Teresi, arXiv:1808.07492 SU(8) might even explain / S. Matsuzaki, K. Nishiwaki and K. Yamamoto, arXiv:1806.02312 SU(4) U(2) SU(2)R in RS background M. Blanke, AC, arXiv:1801.07256 Good solution, but challenging UV completion
Pati-Salam RS Phenomenology M. Blanke, AC, PRL 2018 Modell well motivated + limited but sizable effect
Bildergebnis fr uzh logo QCD corrections to the Matching Perform matching Correct for 4-dimensional Fierz identities Page 13
Results J. Aebischer, AC, C. Greub, 1811.08907 Slightly weaker LHC constraints Page 14
Bildergebnis fr uzh logo Conclusions The Pati-Salam Leptoquark is tailor made to explain the flavour anomalies Explanation of R(D) and R(D*) requires a generic flavour structure: Huge enhancement of b s Sizable loop effects in b sll and b s Explaining R(D) and R(D*) with the Pati-Salam leptoquark give the right loop effects in b sll QCD corrections to the matching make LHC bounds slightly weaker Page 15 Andreas Crivellin
Results I Operators generated by vector leptoquark 2 M VLQ V C VLQ V C 1 C 150log 241 s vector operator F 2 72 2 M VLQ S VLQ S 1 C 24log 49 C C s scalar operator F 2 18 Operators generated by scalar leptoquark 2 17 2 + SLQ V SLQ V 1 3log + C C C s vector operator F 2 4 M 3 2 + SLQ S SLQ S 1 C C C s scalar operator F 2 + SLQ T SLQ T 1 log +2 C C C s tensor operator F 2 M Results independent of the LQ representation Page 16
