scholarly journals Reconciling(g−2)μand charged lepton flavor violating processes through a doubly charged scalar

2016 ◽  
Vol 93 (11) ◽  
Author(s):  
Joydeep Chakrabortty ◽  
Pradipta Ghosh ◽  
Subhadeep Mondal ◽  
Tripurari Srivastava
Keyword(s):  
Charged Lepton ◽  
Charged Scalar ◽  
Lepton Flavor ◽  
Doubly Charged

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 Lepton flavor violation and collider searches in a type I + II seesaw model

2019 ◽  
Vol 79 (11) ◽  
Author(s):  
Manoel M. Ferreira ◽  
Tessio B. de Melo ◽  
Sergey Kovalenko ◽  
Paulo R. D. Pinheiro ◽  
Farinaldo S. Queiroz
Keyword(s):  
Standard Model ◽  
New Physics ◽  
Neutrino Masses ◽  
Type I ◽  
Lepton Flavor Violation ◽  
Charged Scalar ◽  
Lepton Flavor ◽  
Flavor Violation ◽  
The Standard Model ◽  
Doubly Charged

AbstractNeutrinos are massless in the Standard Model. The most popular mechanism to generate neutrino masses are the type I and type II seesaw, where right-handed neutrinos and a scalar triplet are augmented to the Standard Model, respectively. In this work, we discuss a model where a type I + II seesaw mechanism naturally arises via spontaneous symmetry breaking of an enlarged gauge group. Lepton flavor violation is a common feature in such setup and for this reason, we compute the model contribution to the $$\mu \rightarrow e\gamma $$μ→eγ and $$\mu \rightarrow 3e$$μ→3e decays. Moreover, we explore the connection between the neutrino mass ordering and lepton flavor violation in perspective with the LHC, HL-LHC and HE-LHC sensitivities to the doubly charged scalar stemming from the Higgs triplet. Our results explicitly show the importance of searching for signs of lepton flavor violation in collider and muon decays. The conclusion about which probe yields stronger bounds depends strongly on the mass ordering adopted, the absolute neutrino masses and which much decay one considers. In the 1–5 TeV mass region of the doubly charged scalar, lepton flavor violation experiments and colliders offer orthogonal and complementary probes. Thus if a signal is observed in one of the two new physics searches, the other will be able to assess whether it stems from a seesaw framework.

scholarly journals Doubly charged scalar at the High-Luminosity and High-Energy LHC

2019 ◽  
Vol 34 (27) ◽  
pp. 1950157 ◽  
Author(s):  
Tessio B. de Melo ◽  
Farinaldo S. Queiroz ◽  
Yoxara Villamizar
Keyword(s):  
High Energy ◽  
Beyond The Standard Model ◽  
High Luminosity ◽  
Charged Scalar ◽  
Proton Proton ◽  
Model Studies ◽  
Lepton Flavor ◽  
Lepton Colliders ◽  
Charged Leptons ◽  
Doubly Charged

Doubly charged scalars are common figures in several beyond the Standard Model studies, especially those related to neutrino masses. In this work, we estimate the High-Luminosity (HL-LHC) and High-Energy LHC (HE-LHC) sensitivity to doubly charged scalars assuming that they decay promptly and exclusively into charged leptons. Our study focuses on the fit to the same-sign dilepton mass spectra and it is based on proton–proton collisions at 13 TeV, 14 TeV and 27 TeV with integrated luminosity of [Formula: see text] fb[Formula: see text], 3 ab[Formula: see text] and 15 ab[Formula: see text]. We find that HL-LHC may probe doubly charged scalars masses up to 2.3 TeV, whereas HE-LHC can impressively probe masses up to 3 TeV, conclusively constituting a complementary and important probe to signs of doubly charged scalars in lepton flavor violation decays and lepton–lepton colliders.

scholarly journals Doubly Charged Higgs Bosons and Spontaneous Symmetry Breaking at eV and TeV Scales

Symmetry ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 153
Author(s):  
Janusz Gluza ◽  
Magdalena Kordiaczyńska ◽  
Tripurari Srivastava
Keyword(s):  
Gauge Group ◽  
Vacuum Expectation ◽  
Higgs Bosons ◽  
Symmetric Model ◽  
Charged Scalar ◽  
Scalar Particles ◽  
Lepton Flavor ◽  
Triplet Model ◽  
Standard Models ◽  
Doubly Charged

In this paper, beyond standard models are considered with additional scalar triplets without modification of the gauge group (Higgs Triplet Model—HTM) and with an extended gauge group S U ( 2 ) R ⊗ S U ( 2 ) L ⊗ U ( 1 ) (Left–Right Symmetric Model—LRSM). These models differ drastically in possible triplet vacuum expectation values (VEV). Within the HTM, we needed to keep the triplet VEV at most within the range of GeV to keep the electroweak ρ parameter strictly close to 1, down to electronvolts due to the low energy constraints on lepton flavor-violating processes and neutrino oscillation parameters. For LRSM, the scale connected with the S U ( 2 ) R triplet is relevant, and to provide proper masses of non-standard gauge bosons, VEV should at least be at the TeV level. Both models predict the existence of doubly charged scalar particles. In this paper, their production in the e + e − collider is examined for making a distinction in the s- and t- channels between the two models in scenarios when masses of doubly charged scalars are the same.

scholarly journals Charged lepton flavor violating processes in neutrinophilic Higgs + seesaw model

2020 ◽  
Vol 2020 (7) ◽  
Author(s):  
Naoyuki Haba ◽  
Tsuneharu Omija ◽  
Toshifumi Yamada
Keyword(s):  
Charged Lepton ◽  
Higgs Field ◽  
Vacuum Expectation ◽  
Vacuum Expectation Value ◽  
Charged Scalar ◽  
Yukawa Couplings ◽  
Scalar Particles ◽  
Lepton Flavor ◽  
Seesaw Model ◽  
The Right

Abstract We investigate charged lepton flavor violating (CLFV) processes in the “neutrinophilic Higgs + seesaw model”, in which right-handed neutrinos couple only with an extra Higgs field which develops a tiny vacuum expectation value and the right-handed neutrinos also have Majorana mass. The model realizes a seesaw mechanism around TeV scale without extremely small Dirac Yukawa couplings. A phenomenological feature of the model is CLFV processes induced by loop diagrams of the charged scalar particles and heavy neutrinos. Therefore, first we constrain the model’s parameter space from the search for $\mu\to e\gamma$. Next, we predict the branching ratios of other CLFV processes including the $\mu\to3e$, $\mu+{\rm Al}\to e+{\rm Al}$, $\mu+{\rm Ti}\to e+{\rm Ti}$, $Z\to e\mu$, $Z\to e\tau$, $Z\to \mu\tau$, $h\to e\tau$ and $h\to\mu\tau$ processes, and discuss their detectability in future experiments.

scholarly journals Charged lepton flavor violation at the EIC

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Vincenzo Cirigliano ◽  
Kaori Fuyuto ◽  
Christopher Lee ◽  
Emanuele Mereghetti ◽  
Bin Yan
Keyword(s):  
Cross Sections ◽  
Charged Lepton ◽  
Hadron Collider ◽  
Effective Field ◽  
Background Suppression ◽  
Lepton Flavor Violation ◽  
Final State ◽  
Lepton Flavor ◽  
Flavor Violation ◽  
Discovery Potential

Abstract We present a comprehensive analysis of the potential sensitivity of the Electron-Ion Collider (EIC) to charged lepton flavor violation (CLFV) in the channel ep→τX, within the model-independent framework of the Standard Model Effective Field Theory (SMEFT). We compute the relevant cross sections to leading order in QCD and electroweak corrections and perform simulations of signal and SM background events in various τ decay channels, suggesting simple cuts to enhance the associated estimated efficiencies. To assess the discovery potential of the EIC in τ-e transitions, we study the sensitivity of other probes of this physics across a broad range of energy scales, from pp→eτX at the Large Hadron Collider to decays of B mesons and τ leptons, such as τ→eγ, τ→eℓ+ℓ−, and crucially the hadronic modes τ→eY with Y∈π, K, ππ, Kπ, …. We find that electroweak dipole and four-fermion semi-leptonic operators involving light quarks are already strongly constrained by τ decays, while operators involving the c and b quarks present more promising discovery potential for the EIC. An analysis of three models of leptoquarks confirms the expectations based on the SMEFT results. We also identify future directions needed to maximize the reach of the EIC in CLFV searches: these include an optimization of the τ tagger in hadronic channels, an exploration of background suppression through tagging b and c jets in the final state, and a global fit by turning on all SMEFT couplings, which will likely reveal new discovery windows for the EIC.

scholarly journals Searching for charged lepton flavor violation at ep colliders

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Stefan Antusch ◽  
A. Hammad ◽  
Ahmed Rashed
Keyword(s):  
Standard Model ◽  
Charged Lepton ◽  
Neutral Current ◽  
Effective Theory ◽  
Theory Approach ◽  
Lepton Flavor Violation ◽  
Lepton Flavor ◽  
Flavor Violation ◽  
The Standard Model ◽  
Order Of Magnitude

Abstract We investigate the sensitivity of electron-proton (ep) colliders for charged lepton flavor violation (cLFV) in an effective theory approach, considering a general effective Lagrangian for the conversion of an electron into a muon or a tau via the effective coupling to a neutral gauge boson or a neutral scalar field. For the photon, the Z boson and the Higgs particle of the Standard Model, we present the sensitivities of the LHeC for the coefficients of the effective operators, calculated from an analysis at the reconstructed level. As an example model where such flavor changing neutral current (FCNC) operators are generated at loop level, we consider the extension of the Standard Model by sterile neutrinos. We show that the LHeC could already probe the LFV conversion of an electron into a muon beyond the current experimental bounds, and could reach more than an order of magnitude higher sensitivity than the present limits for LFV conversion of an electron into a tau. We discuss that the high sensitivities are possible because the converted charged lepton is dominantly emitted in the backward direction, enabling an efficient separation of the signal from the background.

scholarly journals OBSERVABLE LEPTON FLAVOR SYMMETRY AT LHC

2011 ◽  
Vol 26 (06) ◽  
pp. 377-385 ◽  
Author(s):  
ERNEST MA
Keyword(s):  
Finite Group ◽  
Large Hadron Collider ◽  
Gauge Boson ◽  
Charged Lepton ◽  
Hadron Collider ◽  
Flavor Symmetry ◽  
Final States ◽  
Lepton Flavor ◽  
Yukawa Sector

A model of lepton flavor symmetry is discussed, using the non-Abelian finite group T7 and the gauging of B-L, which has a residual Z3 symmetry in the charged-lepton Yukawa sector, allowing it to be observable at the Large Hadron Collider (LHC) from the decay of the new Z' gauge boson of this model to a pair of scalar bosons which have the unusual highly distinguishable final states τ- τ- μ+ e+.

scholarly journals Discriminating leptonic Yukawa interactions with doubly charged scalar at the ILC

2018 ◽  
Vol 929 ◽  
pp. 193-206 ◽  
Author(s):  
Takaaki Nomura ◽  
Hiroshi Okada ◽  
Hiroshi Yokoya
Keyword(s):  
Charged Scalar ◽  
Doubly Charged
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