scholarly journals Neutrino non-standard interactions meet precision measurements of Neff

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Yong Du ◽  
Jiang-Hao Yu
Keyword(s):  
Neutral Current ◽  
Percent Level ◽  
Coherent Scattering ◽  
Effective Field ◽  
Precision Measurements ◽  
Collision Term ◽  
Vector Type ◽  
Stringent Constraint ◽  
The Standard Model ◽  
Theory Framework

Abstract The number of relativistic species, Neff, has been precisely calculated in the standard model, and would be measured to the percent level by CMB-S4 in future. Neutral-current non-standard interactions would affect neutrino decoupling in the early Universe, thus modifying Neff. We parameterize those operators up to dimension-7 in the effective field theory framework, and then provide a complete, generic and analytical dictionary for the collision term integrals. From precision measurements of Neff, the most stringent constraint is obtained for the dimension-6 vector-type neutrino-electron operator, whose scale is constrained to be above about 195 (331) GeV from Planck (CMB-S4). We find our results complementary to other experiments like neutrino coherent scattering, neutrino oscillation, collider, and neutrino deep inelastic scattering experiments.

scholarly journals Charged lepton flavour violating processes

2019 ◽  
Author(s):  
Adrian Signer
Keyword(s):  
Effective Field Theory ◽  
Charged Lepton ◽  
Experimental Situation ◽  
Specific Model ◽  
Effective Field ◽  
Charged Scalar ◽  
The Standard Model ◽  
Doubly Charged ◽  
Theory Framework ◽  
Lepton Flavour

Charged lepton flavour violating processes are naturally present in many extensions of the Standard Model. After a brief overview on the experimental situation, an effective-field-theory framework is described that allows to interpret and compare the various experiments in a consistent way. The usefulness of this approach is then illustrated in the context of a specific model with a doubly charged scalar.

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 Consistent QFT description of non-standard neutrino interactions

2020 ◽  
Vol 2020 (11) ◽  
Author(s):  
Adam Falkowski ◽  
Martín González-Alonso ◽  
Zahra Tabrizi
Keyword(s):  
Field Theory ◽  
Quantum Field Theory ◽  
New Physics ◽  
Effective Field ◽  
Quantum Field ◽  
The Standard Model ◽  
Mechanical Approach ◽  
Theory Result ◽  
Quantum Mechanical Approach ◽  
Theory Framework

Abstract Neutrino oscillations are precision probes of new physics. Apart from neutrino masses and mixings, they are also sensitive to possible deviations of low-energy interactions between quarks and leptons from the Standard Model predictions. In this paper we develop a systematic description of such non-standard interactions (NSI) in oscillation experiments within the quantum field theory framework. We calculate the event rate and oscillation probability in the presence of general NSI, starting from the effective field theory (EFT) in which new physics modifies the flavor or Lorentz structure of charged-current interactions between leptons and quarks. We also provide the matching between the EFT Wilson coefficients and the widely used simplified quantum-mechanical approach, where new physics is encoded in a set of production and detection NSI parameters. Finally, we discuss the consistency conditions for the standard NSI approach to correctly reproduce the quantum field theory result.

scholarly journals Global constraints on neutral-current generalized neutrino interactions

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
F. J. Escrihuela ◽  
L. J. Flores ◽  
O. G. Miranda ◽  
Javier Rendón
Keyword(s):  
Global Analysis ◽  
Neutral Current ◽  
New Physics ◽  
Effective Field ◽  
Global Constraints ◽  
Neutrino Interactions ◽  
Electron Positron ◽  
The Standard Model ◽  
Low Energies ◽  
Positron Collisions

Abstract We study generalized neutrino interactions (GNI) for several neutrino processes, including neutrinos from electron-positron collisions, neutrino-electron scattering, and neutrino deep inelastic scattering. We constrain scalar, pseudoscalar, and tensor new physics effective couplings, based on the standard model effective field theory at low energies. We have performed a global analysis for the different effective couplings. We also present the different individual constraints for each effective parameter (scalar, pseudoscalar, and tensor). Being a global analysis, we show robust results for the restrictions on the different GNI parameters and improve some of these bounds.

scholarly journals Parametrized classifiers for optimal EFT sensitivity

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Siyu Chen ◽  
Alfredo Glioti ◽  
Giuliano Panico ◽  
Andrea Wulzer
Keyword(s):  
Statistical Learning ◽  
High Energy ◽  
New Physics ◽  
Effective Field ◽  
Analytic Description ◽  
Leptonic Decays ◽  
Learning Classifier ◽  
The Standard Model ◽  
Standard Model Amplitude ◽  
Theory Framework

Abstract We study unbinned multivariate analysis techniques, based on Statistical Learning, for indirect new physics searches at the LHC in the Effective Field Theory framework. We focus in particular on high-energy ZW production with fully leptonic decays, modeled at different degrees of refinement up to NLO in QCD. We show that a considerable gain in sensitivity is possible compared with current projections based on binned analyses. As expected, the gain is particularly significant for those operators that display a complex pattern of interference with the Standard Model amplitude. The most effective method is found to be the “Quadratic Classifier” approach, an improvement of the standard Statistical Learning classifier where the quadratic dependence of the differential cross section on the EFT Wilson coefficients is built-in and incorporated in the loss function. We argue that the Quadratic Classifier performances are nearly statistically optimal, based on a rigorous notion of optimality that we can establish for an approximate analytic description of the ZW process.

scholarly journals Charm physics confronts high-pT lepton tails

2020 ◽  
Vol 2020 (11) ◽  
Author(s):  
Javier Fuentes-Martín ◽  
Admir Greljo ◽  
Jorge Martin Camalich ◽  
José David Ruiz-Alvarez
Keyword(s):  
Effective Field Theory ◽  
Short Distance ◽  
Neutral Current ◽  
New Physics ◽  
Charm Physics ◽  
Effective Field ◽  
Charmed Meson ◽  
Charm Decays ◽  
High Energies ◽  
The Standard Model

Abstract We present a systematic survey of possible short-distance new-physics effects in (semi)leptonic charged- and neutral-current charmed meson decays. Using the Standard Model Effective Field Theory (SMEFT) to analyze the most relevant experimental data at low and high energies, we demonstrate a striking complementarity between charm decays and high invariant mass lepton tails at the LHC. Interestingly enough, high-pT Drell-Yan data offer competitive constraints on most new physics scenarios. Furthermore, the full set of correlated constraints from K, π and τ decays imposed by SU(2)L gauge invariance is considered. The bounds from D(s) decays, high-pT lepton tails and SU(2)L relations chart the space of the SMEFT affecting semi(leptonic) charm flavor transitions.

scholarly journals A low-energy perspective on the minimal left-right symmetric model

2021 ◽  
Vol 2021 (11) ◽  
Author(s):  
W. Dekens ◽  
L. Andreoli ◽  
J. de Vries ◽  
E. Mereghetti ◽  
F. Oosterhof
Keyword(s):  
Dipole Moments ◽  
Global Analysis ◽  
Scalar Fields ◽  
Effective Field ◽  
Low Energy ◽  
Symmetric Model ◽  
Ckm Matrix ◽  
Stringent Constraint ◽  
The Standard Model ◽  
The Right

Abstract We perform a global analysis of the low-energy phenomenology of the minimal left-right symmetric model (mLRSM) with parity symmetry. We match the mLRSM to the Standard Model Effective Field Theory Lagrangian at the left-right-symmetry breaking scale and perform a comprehensive fit to low-energy data including mesonic, neutron, and nuclear β-decay processes, ∆F = 1 and ∆F = 2 CP-even and -odd processes in the bottom and strange sectors, and electric dipole moments (EDMs) of nucleons, nuclei, and atoms. We fit the Cabibbo-Kobayashi-Maskawa and mLRSM parameters simultaneously and determine a lower bound on the mass of the right-handed WR boson. In models where a Peccei-Quinn mechanism provides a solution to the strong CP problem, we obtain $$ {M}_{W_R} $$ M W R ≳ 5.5 TeV at 95% C.L. which can be significantly improved with next-generation EDM experiments. In the P-symmetric mLRSM without a Peccei-Quinn mechanism we obtain a more stringent constraint $$ {M}_{W_R} $$ M W R ≳ 17 TeV at 95% C.L., which is difficult to improve with low-energy measurements alone. In all cases, the additional scalar fields of the mLRSM are required to be a few times heavier than the right-handed gauge bosons. We consider a recent discrepancy in tests of first-row unitarity of the CKM matrix. We find that, while TeV-scale WR bosons can alleviate some of the tension found in the Vud,us determinations, a solution to the discrepancy is disfavored when taking into account other low-energy observables within the mLRSM.

scholarly journals Sterile neutrinos with non-standard interactions in β- and 0νββ-decay experiments

2021 ◽  
Vol 2021 (8) ◽  
Author(s):  
W. Dekens ◽  
J. de Vries ◽  
T. Tong
Keyword(s):  
Effective Field Theory ◽  
Sterile Neutrino ◽  
High Energy ◽  
Effective Field ◽  
Neutrino Masses ◽  
Beyond The Standard Model ◽  
Sterile Neutrinos ◽  
The Standard Model ◽  
O 10 ◽  
Theory Framework

Abstract Charged currents are probed in low-energy precision β-decay experiments and at high-energy colliders, both of which aim to measure or constrain signals of beyond-the-Standard-Model physics. In light of future β-decay and LHC measurements that will further explore these non-standard interactions, we investigate what neutrinoless double-β decay (0νββ) experiments can tell us if a nonzero signal were to be found. Using a recently developed effective-field-theory framework, we consider the effects that interactions with right-handed neutrinos have on 0νββ and discuss the range of neutrino masses that current and future 0νββ measurements can probe, assuming neutrinos are Majorana particles. For non-standard interactions at the level suggested by recently observed hints in β decays, we show that next-generation 0νββ experiments can determine the Dirac or Majorana nature of neutrinos, for sterile neutrino masses larger than $$ \mathcal{O}(10) $$ O 10 eV.

scholarly journals Renormalization Group evolution from on-shell SMEFT

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Minyuan Jiang ◽  
Teng Ma ◽  
Jing Shu
Keyword(s):  
Field Theory ◽  
Renormalization Group ◽  
Standard Model ◽  
Effective Field Theory ◽  
Effective Field ◽  
High Dimensional ◽  
Anomalous Dimensions ◽  
The Standard Model ◽  
Group Evolution

Abstract We describe the on-shell method to derive the Renormalization Group (RG) evolution of Wilson coefficients of high dimensional operators at one loop, which is a necessary part in the on-shell construction of the Standard Model Effective Field Theory (SMEFT), and exceptionally efficient based on the amplitude basis in hand. The UV divergence is obtained by firstly calculating the coefficients of scalar bubble integrals by unitary cuts, then subtracting the IR divergence in the massless bubbles, which can be easily read from the collinear factors we obtained for the Standard Model fields. Examples of deriving the anomalous dimensions at dimension six are presented in a pedagogical manner. We also give the results of contributions from the dimension-8 H4D4 operators to the running of V+V−H2 operators, as well as the running of B+B−H2D2n from H4D2n+4 for general n.

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