scholarly journals The flavor of UV physics

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Sebastian Bruggisser ◽  
Ruth Schäfer ◽  
Danny van Dyk ◽  
Susanne Westhoff
Keyword(s):  
Effective Field Theory ◽  
Top Quark ◽  
New Physics ◽  
Effective Field ◽  
Flavor Symmetry ◽  
Minimal Flavor Violation ◽  
Yukawa Couplings ◽  
Flavor Violation ◽  
Flavor Structure ◽  
The Standard Model

Abstract New physics not far above the TeV scale should leave a pattern of virtual effects in observables at lower energies. What do these effects tell us about the flavor structure of a UV theory? Within the framework of the Standard Model Effective Field Theory (SMEFT), we resolve the flavor structure of the Wilson coefficients in a combined analysis of top-quark and B-physics observables. We assume that the Yukawa couplings are the only sources of flavor symmetry breaking, a framework known as Minimal Flavor Violation. Our fits to LHC and b-factory measurements show that combining top and bottom observables is crucial to pin down possible sources of flavor breaking in a UV theory. This analysis includes the full analytic expansion of SMEFT coefficients in Minimal Flavor Violation and a detailed study of SMEFT effects in b → s flavor transitions.

scholarly journals On stringy origin of minimal flavor violation

2022 ◽  
Vol 82 (1) ◽  
Author(s):  
Tatsuo Kobayashi ◽  
Hajime Otsuka
Keyword(s):  
Field Theory ◽  
Effective Field Theory ◽  
Effective Action ◽  
Effective Field ◽  
Minimal Flavor Violation ◽  
Yukawa Couplings ◽  
Cp Violations ◽  
Flavor Violation ◽  
Zero Modes ◽  
The Standard Model

AbstractWe study the minimal flavor violation in the context of string effective field theory. Stringy selection rules indicate that n-point couplings among fermionic zero-modes and lightest scalar modes in the string effective action are given by a product of Yukawa couplings which are regarded as spurion fields of stringy and geometrical symmetries. Hence, Yukawa couplings determine the dynamics of flavor and CP violations. This observation strongly supports the hypothesis of minimal flavor violation in the Standard Model effective field theory.

scholarly journals Positivity bounds on Minimal Flavor Violation

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Quentin Bonnefoy ◽  
Emanuele Gendy ◽  
Christophe Grojean
Keyword(s):  
Standard Model ◽  
Effective Field ◽  
Minimal Flavor Violation ◽  
Ckm Matrix ◽  
Yukawa Couplings ◽  
Flavor Violation ◽  
Higher Dimensional ◽  
The Standard Model ◽  
The One ◽  
Yukawa Sector

Abstract From general analyticity and unitarity requirements on the UV theory, positivity bounds on the Wilson coefficients of the dimension-8 operators composed of 4 fermions and two derivatives appearing in the Standard Model Effective Field Theory have been derived recently. We explore the fate of these bounds in the context of models endowed with a Minimal Flavor Violation (MFV) structure, models in which the flavor structure of higher dimensional operators is inherited from the one already contained in the Yukawa sector of the Standard Model Lagrangian. Our goal is to check whether the general positivity bounds translate onto bounds on the Yukawa coefficients and/or on elements of the CKM matrix. MFV fixes the coefficients of dimension-8 operators up to some multiplicative flavor-blind factors and we find that, in the most generic setup, the freedom left by those unspecified coefficients is enough as not to constrain the parameters of the renormalizable Yukawa sector. On the contrary, the latter shape the allowed region for the former. Requiring said overall coefficients to take natural $$ \mathcal{O}(1) $$ O 1 values could give rise to bounds on the Yukawa couplings. Remarkably, at leading order in an expansion in powers of the Yukawa matrices, no bounds on the CKM entries can be retrieved.

scholarly journals Long-lived heavy neutral leptons at the LHC: four-fermion single-NR operators

2022 ◽  
Vol 2022 (1) ◽  
Author(s):  
Rebeca Beltrán ◽  
Giovanna Cottin ◽  
Juan Carlos Helo ◽  
Martin Hirsch ◽  
Arsenii Titov ◽  
...  
Keyword(s):  
Field Theory ◽  
Standard Model ◽  
Effective Field Theory ◽  
New Physics ◽  
Effective Field ◽  
High Luminosity ◽  
The Past ◽  
The Standard Model ◽  
Model Independent

Abstract Interest in searches for heavy neutral leptons (HNLs) at the LHC has increased considerably in the past few years. In the minimal scenario, HNLs are produced and decay via their mixing with active neutrinos in the Standard Model (SM) spectrum. However, many SM extensions with HNLs have been discussed in the literature, which sometimes change expectations for LHC sensitivities drastically. In the NRSMEFT, one extends the SM effective field theory with operators including SM singlet fermions, which allows to study HNL phenomenology in a “model independent” way. In this paper, we study the sensitivity of ATLAS to HNLs in the NRSMEFT for four-fermion operators with a single HNL. These operators might dominate both production and decay of HNLs, and we find that new physics scales in excess of 20 TeV could be probed at the high-luminosity LHC.

scholarly journals A Monte Carlo global analysis of the Standard Model Effective Field Theory: the top quark sector

2019 ◽  
Vol 2019 (4) ◽  
Author(s):  
Nathan P. Hartland ◽  
Fabio Maltoni ◽  
Emanuele R. Nocera ◽  
Juan Rojo ◽  
Emma Slade ◽  
...  
Keyword(s):  
Field Theory ◽  
Monte Carlo ◽  
Standard Model ◽  
Effective Field Theory ◽  
Top Quark ◽  
Global Analysis ◽  
Effective Field ◽  
Quark Sector ◽  
The Standard Model

scholarly journals Probing the nonunitarity of the leptonic mixing matrix at the CEPC

2016 ◽  
Vol 31 (33) ◽  
pp. 1644006 ◽  
Author(s):  
Stefan Antusch ◽  
Oliver Fischer
Keyword(s):  
Field Theory ◽  
Standard Model ◽  
Effective Field Theory ◽  
New Physics ◽  
Effective Field ◽  
Neutrino Masses ◽  
Performance Parameters ◽  
The Standard Model ◽  
Mixing Matrix ◽  
Theory Framework

The nonunitarity of the leptonic mixing matrix is a generic signal of new physics aiming at the generation of the observed neutrino masses. We discuss the Minimal Unitarity Violation (MUV) scheme, an effective field theory framework which represents the class of extensions of the Standard Model (SM) by heavy neutral leptons, and discuss the present bounds on the nonunitarity parameters as well as estimates for the sensitivity of the CEPC, based on the performance parameters from the preCDR.

scholarly journals A FB in the SMEFT: precision Z physics at the LHC

2021 ◽  
Vol 2021 (8) ◽  
Author(s):  
Víctor Bresó-Pla ◽  
Adam Falkowski ◽  
Martín González-Alonso
Keyword(s):  
Field Theory ◽  
Standard Model ◽  
Effective Field Theory ◽  
New Physics ◽  
Effective Field ◽  
Precision Measurements ◽  
Vertex Corrections ◽  
The Standard Model ◽  
Electroweak Precision

Abstract We study the forward-backward asymmetry AFB in pp → ℓ+ℓ− at the Z peak within the Standard Model Effective Field Theory (SMEFT). We find that this observable provides per mille level constraints on the vertex corrections of the Z boson to quarks, which close a flat direction in the electroweak precision SMEFT fit. Moreover, we show that current AFB data is precise enough so that its inclusion in the fit improves significantly LEP bounds even in simple New Physics setups. This demonstrates that the LHC can compete with and complement LEP when it comes to precision measurements of the Z boson properties.

scholarly journals Z lepton flavour violation as a probe for new physics at future $$e^+e^-$$ colliders

2021 ◽  
Vol 81 (12) ◽  
Author(s):  
Lorenzo Calibbi ◽  
Xabier Marcano ◽  
Joydeep Roy
Keyword(s):  
Field Theory ◽  
Effective Field Theory ◽  
New Physics ◽  
Effective Field ◽  
Low Energy ◽  
The Standard Model ◽  
Discovery Potential ◽  
Flavour Violation ◽  
Model Independent ◽  
Lepton Flavour

AbstractIn this work we assess the potential of discovering new physics by searching for lepton-flavour-violating (LFV) decays of the Z boson, $$Z\rightarrow \ell _i \ell _j$$ Z → ℓ i ℓ j , at the proposed circular $$e^+e^-$$ e + e - colliders CEPC and FCC-ee. Both projects plan to run at the Z-pole as a “Tera Z factory”, i.e., collecting $${\mathcal {O}}\left( 10^{12} \right) $$ O 10 12 Z decays. In order to discuss the discovery potential in a model-independent way, we revisit the LFV Z decays in the context of the Standard Model effective field theory and study the indirect constraints from LFV $$\mu $$ μ and $$\tau $$ τ decays on the operators that can induce $$Z\rightarrow \ell _i \ell _j$$ Z → ℓ i ℓ j . We find that, while the $$Z\rightarrow \mu e$$ Z → μ e rates are beyond the expected sensitivities, a Tera Z factory is promising for $$Z\rightarrow \tau \ell $$ Z → τ ℓ decays, probing New Physics at the same level of future low-energy LFV observables.

scholarly journals Grand Unified Origin of Gauge Interactions and Families Replication in the Standard Model

Universe ◽  
2021 ◽  
Vol 7 (12) ◽  
pp. 461
Author(s):  
António P. Morais ◽  
Roman Pasechnik ◽  
Werner Porod
Keyword(s):  
Standard Model ◽  
Higgs Doublet ◽  
New Physics ◽  
Effective Field ◽  
Tree Level ◽  
Emergent Properties ◽  
Grand Unified Theory ◽  
Yukawa Couplings ◽  
The Standard Model ◽  
Doublet Model

The tremendous phenomenological success of the Standard Model (SM) suggests that its flavor structure and gauge interactions may not be arbitrary but should have a fundamental first-principle explanation. In this work, we explore how the basic distinctive properties of the SM dynamically emerge from a unified New Physics framework tying together both flavor physics and Grand Unified Theory (GUT) concepts. This framework is suggested by a novel anomaly-free supersymmetric chiral E6×SU(2)F×U(1)F GUT containing the SM. Among the most appealing emergent properties of this theory is the Higgs-matter unification with a highly-constrained massless chiral sector featuring two universal Yukawa couplings close to the GUT scale. At the electroweak scale, the minimal SM-like effective field theory limit of this GUT represents a specific flavored three-Higgs doublet model consistent with the observed large hierarchies in the quark mass spectra and mixing already at tree level.

scholarly journals Beyond the Standard Model physics at CLIC

2020 ◽  
Vol 35 (15n16) ◽  
pp. 2041015 ◽  
Author(s):  
Roberto Franceschini
Keyword(s):  
Field Theory ◽  
Standard Model ◽  
Effective Field Theory ◽  
New Physics ◽  
Effective Field ◽  
Direct Search ◽  
Beyond The Standard Model ◽  
The Standard Model ◽  
Open Issues

A summary of the recent results from CERN Yellow Report on the CLIC potential for new physics is presented. Greater emphasis is put on the direct search for new physics scenarios motivated by the open issues of the Standard Model as well as on interpretations of Standard Model measurements as probes of new physics in the context of effective field theory extensions of the Standard Model.

scholarly journals Top quark decay at next-to-leading order in the standard model effective field theory

2019 ◽  
Vol 100 (5) ◽  
Author(s):  
Radja Boughezal ◽  
Chien-Yi Chen ◽  
Frank Petriello ◽  
Daniel Wiegand
Keyword(s):  
Field Theory ◽  
Standard Model ◽  
Effective Field Theory ◽  
Top Quark ◽  
Effective Field ◽  
Leading Order ◽  
The Standard Model ◽  
Top Quark Decay ◽  
Quark Decay
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