List of examples of charged particles from new physics discussed in this review showing
\r\n\tAn important part of the book will consider electrodes (materials, configurations, contacts with biological matter) as responsible tools for the acquisition of bioimpedance data correctly. Implementations in wearable and implantable health monitors are the proposed book topics. Detecting of different pathogens by the aid of lab-on-chip (LoC) devices for point-of-care (PoC) and need-of-care (NoC) diagnostics is expected. Also, express analysis of biological matter (blood and other body fluids) is included. Electronics connected to electrodes for receiving the bioimpedance signals for further processing belongs to sensing techniques and will be considered.
\r\n\tDevelopment and application of software tools for information extracting from the acquired bioimpedance data, automatic identification of bioparticles and the decision making for diagnosing and treatment are very welcome chapters in the present book.
Charged particles are often considered in the physics beyond the Standard Model (BSM) of particle physics as new heavy particles which are not observed at the experiments. Such charged particles can have rich phenomenology since it would interact with particles in the Standard Model (SM). Furthermore they are motivated to explain some experimental anomalies indicating deviation from predictions in the SM. For example, some charged particle interaction can accommodate with the anomalous magnetic moment of the muon,
where
In this chapter, we review some candidates of new charged particles from BSM physics. After listing some examples of them, the applications to some flavor physics will be discussed focusing on some specific cases. We find it interesting to consider new charged particles which are related to flavor physics in both lepton and quark sectors.
In this section we review some examples of charged particles which are induced from BSM physics.
Singly charged scalar appears from two-Higgs doublet model (2HDM) [17, 18] in which two
where
where all flavor indices are hidden,
where
where
A doubly charged scalar boson also appears from
where
where
where
where
Note that these charged scalars also contribute to lepton flavor violation processes.
The vector-like leptons (VLLs) are discussed in Ref. [29]. They are new charged particles without conflict of gauge anomaly problem and induce rich lepton flavor physics. To obtain mixing with the SM leptons, the representations of VLL under
where we have suppressed the flavor indices;
with
where the basis is chosen such that the SM lepton mass matrices are in diagonalized form,
Note that the elements of
To diagonalize
where
where
If one sets
Here we consider vector-like triplet quarks (VLTQs) that are discussed in Ref. [30] The gauge invariant Yukawa couplings of VLTQs to the SM quarks, to the SM Higgs doublet and to the new Higgs singlet field are written as
where
The electric charges of
where
In this subsection we consider leptoquarks (LQs) which are discussed for example in Refs. [31, 32]. The three LQs are
where the superscripts are the electric charges of the particles. Accordingly, the LQ Yukawa couplings to the SM fermions are expressed as
where the flavor indices are hidden,
The scalar LQs can also couple to the SM Higgs field via the scalar potential, and the cross section for the Higgs to diphoton can be modified in principle. However, the couplings of the LQs to the Higgs are independent parameters and irrelevant to the flavors, so by taking proper values for the parameters, the signal strength parameter for the Higgs to diphoton can fit the LHC data. For detailed analysis see Table 1 in Ref. [31].
Particle type | Examples of application | |
---|---|---|
Charged scalar | Neutrino mass, lepton flavor violation | |
Vector-like lepton | Lepton flavor violation | |
Vector-like quark | Quark flavor physics | |
Scalar leptoquark | Meson decay, lepton flavor violation |
List of examples of charged particles from new physics discussed in this review showing
In this section, we review applications of charged particles to flavor physics by considering VLLs and LQs as examples.
Introduction of VLLs contributes to lepton flavor physics via Yukawa interactions discussed in previous section. Here we review the leptonic decay of the SM Higgs and LFV decay of charged lepton as an illustration based on Ref. [29].
From Eq. (18), it can be seen that the modified Higgs couplings to the SM leptons are proportional lepton masses. By comparison with other lepton channels, it can be seen that the
If the SM Higgs production cross section is not changed, the signal strength for
In the following, we investigate the contributions of new couplings in Eq. (18) to the rare tau decays and to the flavor-conserving muon anomalous magnetic moment. We first investigate the muon
where
Accordingly, the BR for
We present the contours for
Contours for BRτ→μγ (dashed) as a function of Y and mΨ, where the constraint from ΓinvZ (solid) is included. (The plot is taken from ref. [29]).
This section is based on Ref. [32]. Several interesting excesses in semileptonic
where
According to the interactions in Eq. (24), we first formulate the four-Fermi interactions for the
where the indices
With the Yukawa couplings in Eq. (24), the effective Hamiltonian for the
where the Fierz transformations have been applied. By Eq. (31), it can be clearly seen that the quark currents from both the doublet and triplet LQs are left-handed; however, the lepton current from the doublet (triplet) LQ is right(left)-handed. When one includes Eq. (31) in the SM contributions, the effective Hamiltonian for the
where the leptonic currents are denoted by
The effective Wilson coefficients with LQ contributions are expressed as
where
Before we analyze the muon
where
In addition to the muon
with
where
Note that
As mentioned earlier, the singlet LQ does not contribute to
where
In addition to the
where
Using
The observables of
where
where
and the other form factors are taken to be
The values of
f(0) | 0.67 | 0.67 | 0.69 | 0.76 | 0.69 | 0.66 | 0.62 | 0.68 | 0.68 | 0.33 |
0.57 | 0.78 | 0.56 | 0.57 | 0.58 | 0.78 | 1.40 | 0.57 | 0.64 | 1.46 | |
0.41 | ||||||||||
f(0) | 0.36 | 0.36 | 0.35 | 0.44 | 0.45 | 0.36 | 0.32 | 0.39 | 0.39 | 0.27 |
0.43 | 0.70 | 0.43 | 0.45 | 0.46 | 0.64 | 1.23 | 0.45 | 0.72 | 1.31 | |
0.27 | 0.36 | 0.38 | 0.62 | 0.41 |
According to the form factors in Eqs. (44) and (45), and the interactions in Eqs. (30) and (32), we briefly summarize the differential decay rates for the semileptonic
where the
We note that the effective couplings
where
where
From Eq. (52), the measured ratio
After discussing the possible constraints and observables of interest, we now present the numerical analysis to determine the common parameter region where the
The parameters related to the radiative LFV,
where
where
After discussing the constraints and the correlations among various processes, we present the numerical analysis. There are several LQs in this scenario, but we use
(a) Δaμ as a function of k32k˜23 with mΦ=1.5,5,10 TeV, where the band denotes the experimental data with 1σ errors. (b) Contours for RK, Bs→μ+μ−, ΔmBs, and C9LQ,μ as a function of k32k22 and y32y22, where the ranges of RK and Bs→μ+μ− are the experimental values with 1σ errors and mLQ=1.5 TeV. For C9LQ,μ, we show the range for CLQ,μ=−1.5−0.5. (These plots are taken from Ref. [32]).
According to the relationships shown in Eq. (56),
After studying the muon
Contours for (a) RD and (b) RD∗, where the solid lines denote the data with 1σ and 2σ errors, respectively. The horizontal dashed lines in both plots denote the BRexpB+→D∗ℓνℓ, whereas the vertical dotted lines are the BRexpB+→D∗τντ. Contours for (c) RD and (d) RD∗, where the solid and dashed lines denote the situations with and without tensor operator contributions, respectively. In this case, we take mLQ=1.5 TeV. (These plots are taken from ref. [32]).
Contours for BRBc→τν¯τ and RD∗ as a function of w23y˜23 and mS. (The plot is taken from ref. [32]).
Finally, we make some remarks regarding the constraint due to the LQ search at the LHC. Due to the flavor physics constraints, only the
We have reviewed some charged particles which appear from physics beyond the Standard Model of particle physics. Some possible candidates of them are listed such as charged scalar boson, vector-like leptons, vector-like quarks, and leptoquarks. After showing some properties and interactions of these particles, we reviewed some applications to flavor physics in which lepton flavor physics with vector-like lepton and
Charged particles are often considered in the physics beyond the Standard Model (BSM) of particle physics as new heavy particles which are not observed at the experiments. Such charged particles can have rich phenomenology since it would interact with particles in the Standard Model (SM). Furthermore they are motivated to explain some experimental anomalies indicating deviation from predictions in the SM. For example, some charged particle interaction can accommodate with the anomalous magnetic moment of the muon,
where
In this chapter, we review some candidates of new charged particles from BSM physics. After listing some examples of them, the applications to some flavor physics will be discussed focusing on some specific cases. We find it interesting to consider new charged particles which are related to flavor physics in both lepton and quark sectors.
In this section we review some examples of charged particles which are induced from BSM physics.
Singly charged scalar appears from two-Higgs doublet model (2HDM) [17, 18] in which two
where
where all flavor indices are hidden,
where
where
A doubly charged scalar boson also appears from
where
where
where
where
Note that these charged scalars also contribute to lepton flavor violation processes.
The vector-like leptons (VLLs) are discussed in Ref. [29]. They are new charged particles without conflict of gauge anomaly problem and induce rich lepton flavor physics. To obtain mixing with the SM leptons, the representations of VLL under
where we have suppressed the flavor indices;
with
where the basis is chosen such that the SM lepton mass matrices are in diagonalized form,
Note that the elements of
To diagonalize
where
where
If one sets
Here we consider vector-like triplet quarks (VLTQs) that are discussed in Ref. [30] The gauge invariant Yukawa couplings of VLTQs to the SM quarks, to the SM Higgs doublet and to the new Higgs singlet field are written as
where
The electric charges of
where
In this subsection we consider leptoquarks (LQs) which are discussed for example in Refs. [31, 32]. The three LQs are
where the superscripts are the electric charges of the particles. Accordingly, the LQ Yukawa couplings to the SM fermions are expressed as
where the flavor indices are hidden,
The scalar LQs can also couple to the SM Higgs field via the scalar potential, and the cross section for the Higgs to diphoton can be modified in principle. However, the couplings of the LQs to the Higgs are independent parameters and irrelevant to the flavors, so by taking proper values for the parameters, the signal strength parameter for the Higgs to diphoton can fit the LHC data. For detailed analysis see Table 1 in Ref. [31].
Particle type | Examples of application | |
---|---|---|
Charged scalar | Neutrino mass, lepton flavor violation | |
Vector-like lepton | Lepton flavor violation | |
Vector-like quark | Quark flavor physics | |
Scalar leptoquark | Meson decay, lepton flavor violation |
List of examples of charged particles from new physics discussed in this review showing
In this section, we review applications of charged particles to flavor physics by considering VLLs and LQs as examples.
Introduction of VLLs contributes to lepton flavor physics via Yukawa interactions discussed in previous section. Here we review the leptonic decay of the SM Higgs and LFV decay of charged lepton as an illustration based on Ref. [29].
From Eq. (18), it can be seen that the modified Higgs couplings to the SM leptons are proportional lepton masses. By comparison with other lepton channels, it can be seen that the
If the SM Higgs production cross section is not changed, the signal strength for
In the following, we investigate the contributions of new couplings in Eq. (18) to the rare tau decays and to the flavor-conserving muon anomalous magnetic moment. We first investigate the muon