Search

The vector boson dark matter particles which stem from some broken gauge symmetries usually requires some unbroken symmetries to keep themselves stable. In the previous literature, some simplest cases have been discussed, in which the unbroken symmetry is provided by a remnant subgroup of the gauge group. It would be interesting to ask whether all the possible remnant subgroups as well as all the possible coupling forms can be enumerated. Classifying all the Higgs components into different mass degenerate representations to simplify the diagonalization processes is also necessary. Rather than the ambitious target of providing a general solution to all kinds of gauge groups configured with all forms of the Higgs multiplets, in this paper, we concentrate on the case of $\text{SU(2)}_{\text{D}}$ gauge group together with a single Higgs multiplet. We enumerate all possible discrete subgroups that can survive up to $n=21$, where $n$ is the dimension of the Higgs multiplet. We also provide the general algorithms to enumerate all possible renormalizable operators, to write down the general forms of the vacuum expectation value (VEV) configurations, and to give the detailed results of all the mass degenerate irreducible representations embedded in the Higgs multiplet.

In this paper, we discuss the possibility to probe a nearly-degenerate $Z^{\prime}$-$Z$ system by analyzing the $Z$-lineshape at an electron-positron collider. Compared with the usual $Z^{\prime}$ in the literature well separated with the standard model (SM) $Z$ boson in mass, the nearly-degenerate $Z^{\prime}$-$Z$ mixing affects the observed effective ``oblique parameters'' $\tilde{S}$, $\tilde{T}$, $\tilde{U}$, and the effective deviation of ``number of neutrino species'' $\delta \tilde{N}_{\nu}$ in a more complicated way and cannot be simply computed perturbatively up to a particular order. Aiming at solving this problem, we write down a general simplified effective Lagrangian and enumerate some parameter spaces corresponding to some typical models, and suggest a method to extract the constraints by looking into the line-shape of the $Z$-like resonance at an electron-positron collider.

In this paper, we would like to compute the muon anomalous precession frequency through solving the wave functions of the Dirac equations straightforwardly. The precession of a (anti-)muon with an anomalous magnetic momentum term is calculated together with the quantum corrections. Lorentz violation terms up to the lowest non-trivial order is introduced, and their effects on anomalous precession are evaluated perturbatively.

We enumerate various effective couplings that contribute to the mixings between an exotic vector boson $Z^{\prime}$ and the neutral electroweak vector bosons. The miscellaneous mixing patterns can be evaluated perturbatively. The effective oblique parameters $S^{\prime}$, $T^{\prime}$, and $U^{\prime}$ are calculated to compare with the electroweak precision test results. With the contributions to the non-negligible $U^{\prime}$ parameter from the $\epsilon_{B,W}$ parameters and the aid of some other parameters to cancel the negative $T^{\prime}$, the recent CDF $W$-mass anomaly can therefore be explained., Comment: S, T, U parameters are changed to the effective S', T', U'. Further detailed discussions about the parameter definitions and the corresponding effective operators are elaborated in the appendix. Figures are updated

The $\Gamma$-function, or the effective potential of a gauge field theory should comply with the Nielsen identity, which implies how the effective potential evolves as we shift the gauge-fixing term. In this paper, relying on an abelian toy model, we aim at proving this identity in a diagrammatic form with the $\overline{R}_{\xi}$ gauge. The basic idea is to find out the ghost chain after partially differentiating the diagram by the $\xi$ parameter, and shrink the waists of the diagram into points to separate the bulk-part and $C$-part of the diagrams. The calculations can be generalized to the models implemented with non-abelian groups, multiple Higgs and fermion multiplets, and to the finite temperature cases. Inspired by this, we also suggest that when resumming the super-daisy diagrams, one can deduct some irrelevant terms at the connections between the daisy ringlets to fit the Nielsen identity up to arbitrary $\hbar$ orders.

We study the feebly interacting massive particle dark matter whose production processes are significantly affected by the phase evolution and the complicated thermal corrections to the vector boson. We calculate the freeze-in processes to obtain the correct dark matter relic density by enumerating all the possible $1 \leftrightarrow 2$ and $2 \leftrightarrow 2$ processes. The predicted gravitational waves emitted by the first-order phase transitions and the cosmic strings are evaluated.

We propose a vector dark matter model with an exotic dark SU(2) gauge group. Two Higgs triplets are introduced to spontaneously break the symmetry. All of the dark gauge bosons become massive, and the lightest one is a viable vector DM candidate. Its stability is guaranteed by a remaining Z_2 symmetry. We study the parameter space constrained by the Higgs measurement data, the dark matter relic density, and direct and indirect detection experiments. We find numerous parameter points satisfying all the constraints, and they could be further tested in future experiments. Similar methodology can be used to construct vector dark matter models from an arbitrary SO(N) gauge group., Comment: 25 pages, 5 figures

We investigate the potential stochastic gravitational waves from first-order electroweak phase transitions in a model with pseudo-Nambu-Goldstone dark matter and two Higgs doublets. The dark matter candidate can naturally evade direct detection bounds, and can achieve the observed relic abundance via the thermal mechanism. Three scalar fields in the model obtain vacuum expectation values, related to phase transitions at the early Universe. We search for the parameter points that can cause first-order phase transitions, taking into account the existed experimental constraints. The resulting gravitational wave spectra are further evaluated. Some parameter points are found to induce strong gravitational wave signals, which have the opportunity to be detected in future space-based interferometer experiments LISA, Taiji, and TianQin., Comment: 35 pages, 8 figures, accepted for publication in JHEP

In this paper, we will apply the Goldstone equivalence gauge to calculate the $1 \leftrightarrow 2$ processes of a sterile neutrino in the thermal plasma below the standard model (SM) critical temperature $T_c \approx 160 \text{ GeV}$. The sterile neutrino's mass is around the electroweak scale $50 \text{ GeV} \leq m_N \leq 200 \text{ GeV}$, and the acquired thermal averaged effective width $\bar{\Gamma}_{\text{tot}}$ is continuous around the cross-over. We will also apply our results to perform a preliminary calculation of the leptogenesis., Comment: HTL vertex corrections (Eqn.~(A4)) have been included to acquire the gauge invariant results. Data had been updated

If fermionic dark matter (DM) is stabilized by dark $U(1)$ gauge symmetry that is spontaneously broken into its subgroup $Z_2$, the particle contents of the model becomes very rich: DM and excited DM, both of them are Majorana fermions, as well as two dark force mediators, dark photon and dark Higgs boson are naturally present due to the underlying dark gauge symmetry. In this paper, we study the DM bound state formation processes within this scenario, assuming both dark photon and dark Higgs are light mediators and including the effects of excited DM. The Goldstone boson contributions to the potential matrix in the Schr\"{o}dinger equations are found to be important. The emissions of a longitudinal vector boson (or somehow equivalently a Goldstone boson) during the DM bound state formations are crucial to induce a significant reannihilation process, reducing the dark matter relic abundance. Most of the stringent constraints for this kind of dark matter considered in the literature are simply evaded.

Inspired by the Goldstone equivalence gauge, we study the thermal corrections to an originally massive vector boson by checking the poles and branch cuts. We find that part of the Goldstone boson is spewed out from the longitudinal polarization, becoming a branch cut which can be approximated by the "quasi-poles" in the thermal environment. In this case, physical Goldstone boson somehow partly recovers. We also show the Feynmann rules for the "external legs" of these vector boson as well as the recovered Goldstone boson, expecting to simplify the vector boson participated process calculations by adopting the similar "tree-level" logic as in the zero temperature situation. Gauge boson mixing case are also discussed. Similar results are shown in other gauges, especially in the $R_\xi$ gauge., Comment: Typos corrected

We consider the thermal effects into the evaluation of the dark matter production process. With the assistance of the right handed neutrinos, the freeze-in massive particle dark matter production history can be modified by the two-step phase transitions. The kinematic of decay/inverse decay or annihilation processes can be affected by the finite temperature effects as the Universe cools down. The history of the symmetry respected by the model can be revealed by the DM relic abundance evolution processes. The strong first order electroweak phase transition generated gravitational waves can be probed. The number of extra scalars for the Hierarchy problem can be probed through the Higgs off-shell searches at the LHC., Comment: 32 pages, 10 figures, comments welcome

In this paper, we suggest a method of a complete calculation of the Sommerfeld effect in both the s-wave and p-wave annihilation situations. The basic idea is to uniformly consider the equal-time Beth-Salpeter wave functions of both the dark matter and the final state particles, then short-distance interactions can be parametrized as a cross-term considering the equations. Solving these equations will result in the complete formulas of the cross sections with the Sommerfeld effects., Comment: Accepted by PRD. References have been updated, further discussions are added

The physics of the solar dark matter (DM) that are captured and thermalise through the DM-nucleon interaction has been extensively studied. In this work, we consider the leptophilic DM scenario where the DM particles interact exclusively with the electrons through the axial-vector coupling. We investigate relevant phenomenologies in the Sun, including its capture, evaporation and thermalisation, and we calculate the equilibrium distribution using the Monte Carlo methods, rather than adopting a semi-analytic approximation. Based on the analysis, we then determine the minimum testable mass for which the DM-electron coupling strength can be probed via the neutrino observation. Compared to the case of the DM-nucleon interaction, it turns out that minimum detectable mass of the DM-electron interaction is roughly 1 GeV smaller, and a cross section about two orders of magnitude larger is required for the saturation of the annihilation signal., Comment: 16 pages. Version accepted for publication in JCAP

We show the 13 TeV proton-proton collider simulation in a $\nu$-two-Higgs-doublet-model ($\nu$-THDM). The heavy charged Higgs bosons are produced in pairs through the electroweak processes and decay to the light sterile neutrinos. The light sterile neutrino further decays into a jet-like object with a muon in it. This helps us discriminate the signal from the backgrounds with the standard model jets.

We study the recent $e^\pm$ cosmic ray excess reported by DAMPE in a Hidden Valley Model with lepton-portal dark matter. We find the electron-portal can account for the excess well and satisfy the DM relic density and direct detection bounds, while electron+muon/electron+muon+tau-portal suffers from strong constraints from lepton flavor violating observables, such as $\mu \to 3 e$. We also discuss possible collider signatures of our model, both at the LHC and a future 100 TeV hadron collider., Comment: invited by Science China, accepted version

In this paper, we discuss and calculate the electroweak parameters $R_l$, $A_l$, and $N_{\nu}^l$ in a model that combine inverse seesaw with the scotogenic model. Dark matter relic density is also considered. Due to the stringent constraint from the ATLAS experimental data, it is difficult to detect the loop effect on $R_l$, $A_l$ in this model considering both the theoretical and future experimental uncertainties. However, $N_{\nu}^l$ can sometimes become large enough for the future experiments to verify.

In this paper, we combine the $\nu$-Two-Higgs-Doublet-Model ($\nu$THDM) with the inverse seesaw mechanisms. In this model, the Yukawa couplings involving the sterile neutrinos and the exotic Higgs bosons can be of order one in the case of a large $\tan \beta$. We calculated the corrections to the Z-resonance parameters $R_{l_i}$, $A_{l_i}$, $N_{\nu}$, together with the $l_1 \rightarrow l_2 \gamma$ branching ratios, and the muon anomalous $g-2$. Compared with the current bounds and plans for the future colliders, we find that the corrections to the electroweak parameters can be contrained or discovered in much of the parameter space.

In this paper, we calculate the relic abundance of the dark matter particles when they can annihilate into sterile neutrinos with the mass $\lesssim 100 \text{ GeV}$ in a simple model. Unlike the usual standard calculations, the sterile neutrino may fall out of the thermal equilibrium with the thermal bath before the dark matter freezes out. In such a case, if the Yukawa coupling $y_N$ between the Higgs and the sterile neutrino is small, this process gives rise to a larger $\Omega_{\text{DM}} h^2$ so we need a larger coupling between the dark matter and the sterile neutrino for a correct relic abundance.

We study the exotic decay of the 125 GeV Higgs boson ($h$) into a pair of light spin-0 particles ($\phi$) which subsequently decays and results in a $4b$ final state. This decay mode is well motivated in the Next to Minimal Supersymmetric Standard Model (NMSSM) and extended Higgs sector models. Instead of searching at the Large Hadron Collider (LHC) and the High Luminosity Large Hadron Collider (HL-LHC) which are beset by large Standard Model (SM) backgrounds, we investigate this decay channel at the much cleaner Large Hadron Electron Collider (LHeC). With some simple selection cuts this channel becomes nearly free of background at this $ep$ machine, in stark contrast with the situation at the (HL-)LHC. With a parton level analysis we show that for the $\phi$ mass range $[20,60]GeV$, with $100\,fb^{-1}$ luminosity the LHeC is generally capable of constraining $C_{4b}^2\equiv\kappa_{V}^2\times\text{Br}(h\rightarrow\phi\phi)\times\text{Br}^2(\phi\rightarrow b\bar{b})$ ($\kappa_{V}$ denotes the $hVV(V=W,Z)$ coupling strength relative to the SM value) to a few percent level ($95\%$ CLs). With $1\,ab^{-1}$ luminosity $C_{4b}^2$ at a few per mille level can be probed. These sensitivities are much better than the HL-LHC performance and demonstrate the important role expected to be played by the LHeC in probing exotic Higgs decay processes, in addition to the already proposed invisible Higgs decay channel., Comment: 10 pages, 5 figures. Version accepted by EPJC. Tables and figures updated after correcting a mistake in signal event generation. Results essentially unchanged

In this paper, we discuss the MSSM extended with one vector-like lepton doublets $L$-$\overline{L}$ and one right-handed neutrino $N$. The neutral vecotor-like sneutrino can be a candidate of dark matter. In order to avoid the interaction with the necleons by exchanging a $Z$-boson, the mass splitting between the real part and the imaginary part of the sneutrino field is needed. Compared with the MSSM sneutrino dark matter, the mass splitting between the vector-like sneutrino field can be more naturally acquired without large A-terms and constraints on the neutralino masses. We have also calculated the relic density and the elastic scattering cross sections with the neucleons in the cases that the dark matter particles coannihilate with or without the MSSM slepton doublets. The elastic scattering cross sections with the neucleons are well below the LUX bounds. In the case that the dark matter coannihilate with all the MSSM slepton doublets, the mass of the dark matter can be as light as 370 GeV.

We investigate the parameter space of a model which extends next to minimal supersymmetric standard model (NMSSM) with the vectorlike (VL) particles. We find that the $10+\overline{10}$ model can explain the possible diphoton excess recently revealed by the ATLAS and CMS collaborations, although the predicted signal strength is a little smaller than the observed one.

We construct a weakly-coupled renormalizable model to explain the $750\mbox{GeV}$ diphoton excess. The $750\mbox{GeV}$ resonance (denoted as $X(750)$) is interpreted as a pseudoscalar coming from a complex singlet. The model also naturally provides a dark matter candidate. One most attractive feature of the model is that decays of $X(750)$ are all loop-induced so the diphoton rate is not diluted by unwanted tree level branching fractions. Relevant Yukawa interactions need not to be tuned to near non-perturbative region to explain the rate. The model is highly predictive, including the pseudoscalar nature of $X(750)$, and two nearly mass-degenerate exotic quarks carrying electric charge $5/3$ and $2/3$, respectively. Rich phenomenology is expected with respect to collider searches, flavor physics and dark matter detection, if $X(750)$ can be pinned down by future LHC experiments., Comment: 6 pages, 1 figure. Presentation refined. References updated

In this paper, we will discuss a specific case that the dark matter particles annihilate into right-handed neutrinos. We calculate the predicted gamma-ray excess from the galactic center and compare our results with the data from the Fermi-LAT. An approximately 10-60 GeV right-handed neutrino with heavier dark matter particle can perfectly explain the observed spectrum. The annihilation cross section $\langle \sigma v \rangle$ falls within the range $0.5$-$4 \times 10^{-26} \text{ cm}^3/\text{s}$, which is roughly compatible with the WIMP annihilation cross section., Comment: 11 pages, 5 figures

In this paper, we consider a solution to explain the three discrepancies with the standard model (SM) predictions in flavor observables, i.e. anomalies in $B\rightarrow K^\ast\mu^+\mu^-$ and $R_K=\mathcal{B}(B\rightarrow K\mu^+\mu^-)/\mathcal{B}(B\rightarrow K e^+e^-)$ at the LHCb and an excess in $h\rightarrow \mu\tau$ at the CMS in the context of R-parity violating (RPV) supersymmetry. We demonstrate that these anomalies can be explained within a unified framework: the minimal supersymmetry model (MSSM) extended with $5+\overline{5}$ vectorlike (VL) particles. The new trilinear RPV couplings involving VL particles in our model can solve the $b\rightarrow s$ anomalies , and the mixing between the SM-like Higgs boson and the VL sneutrino can yield the extra $h \rightarrow \mu \tau$ decay mode., Comment: 15 pages

The possibility that the 125 GeV Higgs boson may decay into invisible non-standard-model (non-SM) particles is theoretically and phenomenologically intriguing. In this letter we investigate the sensitivity of the Large Hadron Electron Collider (LHeC) to an invisibly decaying Higgs, in its proposed high luminosity running mode. We focus on the neutral current Higgs production channel which offers more kinematical handles than its charged current counterpart. The signal contains one electron, one jet and large missing energy. With a cut-based parton level analysis, we estimate that if the $hZZ$ coupling is at its standard model (SM) value, then assuming an integrated luminosity of $1\,\mbox{ab}^{-1}$ the LHeC with the proposed 60 GeV electron beam (with $-0.9$ polarization) and 7 TeV proton beam is capable of probing $\mathrm{Br}(h\rightarrow E\!\!\!\!/_T)=6\%$ at $2\sigma$ level. Good lepton veto performance (especially hadronic $\tau$ veto) in the forward region is crucial to the suppression of the dominant $Wje$ background. We also explicitly point out the important role that may be played by the LHeC in probing a wide class of exotic Higgs decay processes and emphasize the general function of lepton-hadron colliders in precision study of new resonances after their discovery in hadron-hadron collisions., Comment: 6 pages, 3 figures. Description of the backgrounds, analysis and results is simplified. Results unchanged with respect to v2. References updated

The idea that the new particles invented in some models beyond the standard model can appear only inside the loops is attractive. In this paper, we fill these loops with off-shell tachyons, leading to a solution of the zero results of the loop diagrams involving the off-shell non-tachyonic particles. We also calculate the Passarino-Veltman $A_0^o$ and $B_0^o$ of the off-shell tachyons.

The see-saw mechanism is usually applied to explain the lightness of neutrinos. The traditional see-saw mechanism introduces at least two right-handed neutrinos for the realistic neutrino spectrum. In the case of supersymmetry, loop corrections can also contribute to neutrino masses, which lead to the possibility to generate the neutrino spectrum by introducing just one right-handed neutrino. To be realistic, MSSM suffers from the mu problem and other phenomenological difficulties, so we extend NMSSM (the MSSM with a singlet S) by introducing one single right-handed neutrino superfield (N) and relevant phenomenology is discussed, Comment: 20 pages, 7 figures

The minimal supersymmetry standard model (MSSM) extended with vector-like theories have long been discussed. If we extend the vector-like MSSM theory into NMSSM and let the vector-like particles couple with the singlet (S), we find out a natural way to generate the vector-like particle masses near 1TeV through the breaking of the Z_3 group. Compared with MSSM+vectorlike models, vector-like models extended into NMSSM contain more yukawa couplings and can help us adjust the renormalization group (RG) trajectories of the gauge couplings in order to unify the intersections. They can also help press down the gauge RG-beta functions for a 5+5bar+10+10bar model, in order for the RG-trajectories of the gauge couplings to unify before the Landau-pole. We also discuss the higgs mass contributed from the vector-like sectors in this case., Comment: 21 pages, 1 table, 5 figures

Phenomenological analysis to the R-parity violating supersymmetry with a vector-like extra generation is performed in detail. It is found that, via the trilinear couplings, the correct neutrino spectrum can be obtained. The Higgs mass rises to 125 GeV by new up-type Yukawa couplings of vector-like quarks with no need of very heavy superpartners. Phenomena of new heavy fermions at LHC are predicted., Comment: 30 pages, 1 table, 7 figures. Accepted for publication in Phys. Rev. D