Z' gauge bosons arise in many particle physics models as mediators between the dark and visible sectors. We exploit dark matter complementarity and derive stringent and robust collider, direct and indirect constraints, as well as limits from the muon magnetic moment. We rule out almost the entire region of the parameter space that yields the right dark matter thermal relic abundance, using a generic parametrization of the Z'-fermion couplings normalized to the Standard Model Z-fermion couplings for dark matter masses in the 8 GeV-5 TeV range. We conclude that mediators lighter than 2.1 TeV are excluded regardless of the DM mass, and that depending on the Z'-fermion coupling strength much heavier masses are needed to reproduce the DM thermal relic abundance while avoiding existing limits.
We discuss the phenomenology of an MeV-scale Dirac fermion coupled to the Standard Model through a dark photon with kinetic mixing with the electromagnetic field. We compute the dark matter relic density and explore the interplay of direct detection and accelerator searches for dark photons. We show that precise measurements of the temperature and polarization power spectra of the Cosmic Microwave Background Radiation lead to stringent constraints, leaving a small window for the thermal production of this MeV dark matter candidate. The forthcoming MeV gamma-ray telescope e-ASTROGAM will offer …
We consider simple dark matter extensions of the standard model in $Z^\prime$ portal scenarios inspired by grand unification theory constructions and we study the phenomenology of such models by considering Spin Dependent and Spin Independent direct detection constraints, confronting the canonical thermally produced dark matter scenario and we show that in this simple framework the combination and the complementary of these constraints is a powerful tool to derive stringent bounds and to reduce the viable parameter space of the model.
We present an extensive analysis of a model in which the (Majorana) Dark Matter candidate is a mixture between a SU(2) singlet and two SU(2) doublets. This kind of setup takes the name of singlet-doublet model. We will investigate in detail an extension of this model in which the Dark Matter sector interactions with a 2-doublet Higgs sector enforcing the complementarity between Dark Matter phenomenology and searches of extra Higgs bosons.
Search for the production of dark Higgs in the framework of Mono-Z$^{\prime}$ portal at the FCC-ee simulated electron-positron collisions at $\sqrt{s} = 240$ GeV
Centre for Theoretical Physics, The British University in Egypt（埃及英国大学理论物理中心）；Istituto Nazionale di Fisica Nucleare, Sezione di Bari（意大利国家核物理研究所巴里分部）；Politecnico di Bari（巴里理工大学）
We extend the standard model with three right-handed singlet neutrinos and a real singlet scalar. We impose two $Z_2$ and $Z_2^\prime$-symmetries. We explain the tiny neutrino mass-squared differences with two $Z_2$- and $Z_2^\prime$-even right-handed neutrinos using the type-I seesaw mechanism. The $Z_2$-odd fermion and the $Z_2^\prime$-odd scalar can both serve as viable dark matter candidates. We identify new regions in the parameter space which are consistent with relic density of the dark matter, recent direct search experiment LUX-2016, XENON1T-2017 and LHC data.
We propose a grand unified SU(5)$\times$U(1)$_X$ model, where the standard SU(5) grand unified theory is supplemented by minimal seesaw and a right-handed neutrino dark matter with an introduction of a global $Z_2$-parity. In the presence of three right-handed neutrinos (RHNs), the model is free from all gauge and mixed-gravitational anomalies. The SU(5) symmetry is broken into the Standard Model (SM) gauge group at $M_{\rm GUT} \simeq 4 \times 10^{16}$ GeV in the standard manner, while the U(1)$_X$ symmetry breaking occurs at the TeV scale, which generates the TeV-scale mass of the U(1)$_X$ g…
We propose to generalize the extensions of the Standard Model where the $Z$ boson serves as a mediator between the Standard Model sector and the dark sector $χ$. We show that, like in the Higgs portal case, the combined constraints from the recent direct searches restrict severely the nature of the coupling of the dark matter to the $Z$ boson and set a limit $m_χ\gtrsim 200$ GeV (except in a very narrow region around the $Z-$pole region). Using complementarity between spin dependent, spin independent and FERMI limits, we predict the nature of this coupling, more specifically the axial/vectoria…
We consider the Singlet Majorana fermion dark matter model, in which the standard model particles interact with the dark sector through the mixing of a singlet scalar and the Higgs boson. In this model both the dark matter and the singlet scalar carry lepton number, the latter being a bilepton. We suppose the existence of a $Z_2$ symmetry, remnant of some high energy local symmetry breaking, that stabilizes the Majorana fermion. We analyzed the parameter space of this model and found that the lepton number symmetry breaking scale, drove by the singlet scalar, is constrained to be within hundre…
We investigate the phenomenology of scalar singlet dark matter candidates that couple dominantly to the Standard Model via a Yukawa interaction with the top quark and a colored vector-like fermion. We estimate the viability of this vector-like portal scenario with respect to the most recent bounds from dark matter direct and indirect detection, as well as to dark matter and vector-like mediator searches at colliders. Moreover, we take QCD radiative corrections into account in all our theoretical calculations. This work complements analyses related both to models featuring a scalar singlet coup…
We study the direct-detection rate for axial-vectorial dark matter scattering off nuclei in an $\mathrm{SU}(2)\times \mathrm{U}(1)$ invariant effective theory and compare it against the LHC reach. Current constraints from direct detection experiments are already bounding the mediator mass to be well into the TeV range for WIMP-like scenarios. This motivates a consistent and systematic exploration of the parameter space to map out possible regions where the rates could be suppressed. We do indeed find such regions and proceed to construct consistent UV models that generate the relevant effectiv…
We introduce a light dark photon $A_μ^\prime$ to the minimal Higgs portal model, by coupling the Higgs boson to "dark QED" containing fermionic dark matter, which gives rise to rich and interesting collider phenomenology. There are two prominent features in such a simple extension -- the Higgs boson could have decays into the long-lived dark photon through the "mono-$A^\prime$ channel," or into multiple collimated leptons via "darkonium," depending on the mixing parameter of the $A_μ^\prime$ with the visible photon. We initiate a study on the possibility of probing the parameter space of the m…
Search for the production of dark matter in the framework of Mono-Z$^{\prime}$ portal at the ILC simulated electron-positron collisions at $\sqrt{s} = 500$ GeV
Complementarity of muon-conversion and linear collider-based experiments for lepton-flavor violating U(1) gauge bosons
一般来说，扩展标准模型的尝试将包括额外的量规结构。我们参数化弦和Technicolor模型的Z'玻色子与原始轻子味违反相互作用。本文计算了它在钛上的μ子转换率（μ N -> e N），并用来说明布鲁克海文国家实验室即将进行的MECO实验和日本强子装置的PRIME实验的潜力。在合理选择参数的情况下，这种质量为10 TeV量级、μ e Z'电荷低至~10^-5的U（1）玻色子被证明可以用于MECO和PRIME。此外，演示的互补性的参数空间覆盖未来的对撞机和μ子转换实验。
We study a model of spin-1 dark matter which interacts with the Standard Model predominantly via exchange of Higgs bosons. We propose an alternative UV completion to the usual Vector Dark Matter Higgs Portal, in which vector-like fermions charged under SU(2)$_W \times$ U(1)$_Y$ and under the dark gauge group, U(1)$^\prime$, generate an effective interaction between the Higgs and the dark matter at one loop. We explore the resulting phenomenology and show that this dark matter candidate is a viable thermal relic and satisfies Higgs invisible width constraints as well as direct detection bounds.
The DAMPE experiment has recently reported strong indications for the existence of an excess of high-energy electrons and positrons. If interpreted in terms of the annihilation of dark matter, the DAMPE result restricts the dark matter mass and possible annihilation channels to a few case. In this paper we explain the DAMPE result with the electron-flavored $Z^\prime$-portal fermionic dark matter. We show that the Dirac dark matter scenario is promising to explain the excess via the process $\bar χχ\to\mathbf{Z}'\to \bar e e$. The reduced annihilation cross section is limited in a range of $10…
We study the possibility of light Dirac neutrino portal dark matter (DM) in an effective field theory setup. Dirac nature of light neutrino automatically includes its right chiral part $ν_R$ which, in our setup, also acts like a portal between DM and the standard model (SM) particles. Considering a Dirac fermion singlet DM stabilized by an unbroken $Z_2$ symmetry, we write down all possible dimension-6 effective operators involving DM-$ν_R$ as well as $ν_R$-SM which conserve $Z_2$, global lepton number and SM gauge symmetries. DM thermalization also ensures the thermalization of $ν_R$, leading…
We consider a concise dark matter scenario in the minimal gauged $B-L$ extension of the Standard Model (SM), where the global $B-L$ (baryon number minus lepton number) symmetry in the SM is gauged, and three generations of right-handed neutrinos and a $B-L$ Higgs field are introduced. Associated with the $B-L$ gauge symmetry breaking by a VEV of the $B-L$ Higgs field, the seesaw mechanism for generating the neutrino mass is automatically implemented after the electroweak symmetry breaking in the SM. In this model context, we introduce a $Z_2$-parity and assign an odd parity for one right-hande…
In this review article, we consider a dark matter scenario in the context of the minimal extension of the Standard Model (SM) with a $B-L$ (baryon number minus lepton number) gauge symmetry, where three right-handed neutrinos with a $B-L$ charge $-1$ and a $B-L$ Higgs field with a $B-L$ charge $+2$ are introduced to make the model anomaly-free and to break the $B-L$ gauge symmetry, respectively. The $B-L$ gauge symmetry breaking generates the Majorana masses for the right-handed neutrinos. We introduce a Z$_2$ symmetry to the model and assign an odd parity only for one right-handed neutrino, a…
We present a comprehensive study of Majorana dark matter in a $U(1)_{B-L}$ gauge extension of the standard model, where three exotic fermions with $B-L$ charges as $-4, -4, +5$ are added to make the model free from the triangle gauge anomalies. The enriched scalar sector and the new heavy gauge boson $Z^{\prime},$ associated with the $U(1)_{B-L}$ symmetry make the model advantageous to be explored in dual portal scenarios for the search of dark matter signal. Diagonalizing the exotic fermion mass matrix, we obtain the Majorana mass eigenstates, of which the lightest one plays the role of dark …
We study the cosmology and LHC phenomenology of a consistent strongly interacting dark sector coupled to Standard Model particles through a generic vector mediator. We lay out the requirements for the model to be cosmologically viable, identify annihilations into dark vector mesons as the dominant dark matter freeze-out process and discuss bounds from direct detection. At the LHC the model predicts dark showers, which can give rise to semi-visible jets or displaced vertices. Existing searches for di-jet resonances and for missing energy mostly probe the parameter regions where prompt decays ar…
The Dark Axion Portal provides a model for Dark Matter (DM) in which both Dark Photons $γ^\prime$ and Axions $a$ can contribute to the present day abundance of DM. We study the parameter space of the Dark Axion Portal to pinpoint regions of the parameter space where $γ^\prime$ and $a$ can be produced with sufficient abundance to account for the cosmic DM density, while still being detectable in planned direct detection and axion haloscope experiments. In particular, we explore the production of eV-scale Dark Photons in the Dark Axion Portal, taking into account a possible kinetic mixing betwee…
We study a multi-component dark matter model where interactions with the Standard Model are primarily via the Higgs boson. The model contains vector-like fermions charged under $SU(2)_W \times U(1)_Y$ and under the dark gauge group, $U(1)^\prime$. This results in two dark matter candidates. A spin-1 and a spin-1/2 candidate, which have loop and tree-level couplings to the Higgs, respectively. We explore the resulting effect on the dark matter relic abundance, while also evaluating constraints on the Higgs invisible width and from direct detection experiments. Generally, we find that this model…
We explore the possibility of having a fermionic dark matter candidate within $U(1)'$ models for CE$ν$NS experiments in light of the latest COHERENT data and the current and future dark matter direct detection experiments. A vector-like fermionic dark matter has been introduced which is charged under $U(1)'$ symmetry, naturally stable after spontaneous symmetry breaking. We perform a complementary investigation using CE$ν$NS experiments and dark matter direct detection searches to explore dark matter as well as $Z^{\prime}$ boson parameter space. Depending on numerous other constraints arising…
We revisit the status of a Majorana fermion as a dark matter candidate when a sequential Z' gauge boson dictates the dark matter phenomenology. Direct dark matter detection signatures rise from dark matter-nucleus scatterings at bubble chamber and liquid xenon detectors, and from the flux of neutrinos from the Sun measured by the IceCube experiment, which is governed by the spin-dependent dark matter-nucleus scattering. On the collider side, LHC searches for dilepton and mono-jet + missing energy signals play an important role. The relic density and perturbativity requirements are also address…
Dirac fermion dark matter models with heavy $Z^{\prime}$ mediators are subject to stringent constraints from spin-independent direct searches and from LHC bounds, cornering them to live near the $Z^{\prime}$ resonance. Such constraints can be relaxed, however, by turning off the vector coupling to Standard Model fermions, thus weakening direct detection bounds, or by resorting to light $Z^{\prime}$ masses, below the Z pole, to escape heavy resonance searches at the LHC. In this work we investigate both cases, as well as the applicability of our findings to Majorana dark matter. We derive colli…
We introduce a dark neutrino sector which respects a hidden $U(1)^\prime$ gauge symmetry, subsequently broken by the vacuum expectation value of a dark scalar. The model is a self-consistent realisation of an extended hidden sector that communicates with the SM only via the three renormalizable portals, namely neutrino, vector and scalar mixing. The interplay between portal couplings leads to several novel signatures in heavy neutrino, dark photon, and dark scalar searches, typically characterised by multi-leptons plus missing energy and displaced vertices. A striking signature arises in kaon …
We consider a concise dark matter (DM) scenario in the context of a non-exotic U(1) extension of the Standard Model (SM), where a new U(1)$_X$ gauge symmetry is introduced along with three generation of right-handed neutrinos (RHNs) and an SM gauge singlet Higgs field. The model is a generalization of the minimal gauged U(1)$_{B-L}$ (baryon number minus lepton number) extension of the SM, in which the extra U(1)$_X$ gauge symmetry is expressed as a linear combination of the SM U(1)$_Y$ and U(1)$_{B-L}$ gauge symmetries. We introduce a $Z_2$-parity and assign an odd-parity only for one RHN amon…
Dark photon portal dark matter with low-temperature reheating
School of Physics and Technology, University of Jinan（济南大学物理科学与技术学院）；School of Physics and Electronic Engineering, Jining University（济宁学院物理与电气工程学院）；Department of Physics and Institute of Theoretical Physics, Nanjing Normal University（南京师范大学物理系和理论物理研究所）
We consider a model in which dark matter is a light (350 MeV) Dirac fermion which couples to quarks as an axial-vector current. At center-of-mass (CM) energies below the confinement scale, such a DM interaction structure may be described through its low energy effective couplings to mesons. In this paper we focus on dark matter annihilation into these final state mesons, and its resulting photon spectrum. We present a coarse-grained approach for analyzing our model in which we argue the meson spectrum solely from kinematics and symmetries and thereby estimate the total DM annihilation cross se…
We consider a non-exotic gauged U(1)$_X$ extension of the Standard Model (SM), where the U(1)$_X$ charge of a SM field is given by a linear combination of its hypercharge and Baryon-minus-Lepton ($B-L$) number. All the gauge and mixed gauge-gravitational anomalies are cancelled in this model with the introduction of three right-handed neutrinos (RHNs). Unlike the conventional minimal U(1)$_X$ model, where a universal U(1)$_X$ charge of $-1$ is assigned to three RHNs, we consider an alternative charge assignment, namely, two RHNs ($N_R^{1,2}$) have U(1)$_X$ charge $-4$ while one RHN ($N_R$) has…
We fully explore the thermal freezeout histories of a vector-portal dark matter model, in the region of parameter space in which the ratio of masses of the dark photon $A^{\prime}$ and dark matter $χ$ is in the range $1 \lesssim m_{A^{\prime}}/m_χ \lesssim 2$. In this region $2 \rightarrow 2$ and $3 \rightarrow 2$ annihilation processes within the dark sector, as well as processes that transfer energy between the dark sector and the Standard Model, play important roles in controlling the thermal freezeout of the dark matter. We carefully track the temperatures of all species, relaxing the assu…
School of Physics and Astronomy, University of Southampton（南安普顿大学物理与天文学院）；Department of Physics, Lund University（隆德大学物理系）；Departamento de Física da Universidade de Aveiro（阿威罗大学物理系）；Centre for Research and Development in Mathematics and Applications (CIDMA)（数学与应用研发中心（CIDMA））；Laboratório de Instrumentação e Física Experimental de Partículas (LIP), Universidade do Minho（米尼奥大学粒子实验与仪器实验室（LIP））；Departamento de Física, Escola de Ciências, Universidade do Minho（米尼奥大学理学院物理系）；Khon Kaen Particle Physics and Cosmology Theory Group (KKPaCT), Department of Physics, Faculty of Science, Khon Kaen University（孔敬大学理学院物理系孔敬粒子物理与宇宙学理论组（KKPaCT））
We investigate the prospects of searching dark sector models via exotic Z-boson decay at future $e^+ e^-$ colliders with Giga Z and Tera Z options. Four general categories of dark sector models: Higgs portal dark matter, vector portal dark matter, inelastic dark matter and axion-like particles, are considered. Focusing on channels motivated by the dark sector models, we carry out a model independent study of the sensitivities of Z-factories in probing exotic decays. The limits on branching ratios of the exotic Z decay are typically $\mathcal{O} (10^{-6} - 10^{-8.5}) $ for the Giga Z and $\math…
Search for the production of dark gauge bosons in the framework of Einstein-Cartan portal in the simulation of proton-proton collisions at $\sqrt{s} = 13.6$ TeV
Reviving $Z^\prime$ Portal Dark Matter with Conversion Mechanism
School of Physics and Technology, University of Jinan（济南大学物理科学与技术学院）；State Key Laboratory of Dark Matter Physics, School of Physics and Astronomy, Shanghai Jiao Tong University（上海交通大学物理与天文学院暗物质物理全国重点实验室）；School of Physical Science and Intelligent Engineering, Jining University（济宁学院物理科学与智能工程学院）
The $Z'$-portal is one of most popular and well-explored scenarios of dark matter (DM). To avoid the strong constraints coming from dilepton resonance searches at the LHC and direct detection of DM, it is usually required that in addition to being leptophobic, the $Z'$ is axially coupled to either the (fermionic) DM or the standard model (SM) quarks. The first possibility has been extensively studied both in the context of simplified model and UV complete scenarios. However, the studies on the second possibiliy are largely confined to simplified models only. Here, we construct the minimal UV c…
This article provides the calculation of an effective vertex function between a nucleon and a $Z^\prime$ boson that couples preferentially to either the top quark or the third generation of fermions, for the purpose of calculating vector-portal dark matter nuclear recoil cross sections. Mixing effects between the new gauge group $U(1)^\prime$ and the Standard Model hypercharge group $U(1)_Y$ are taken into account. Contributions to the $U(1)^\prime$ nucleon current from heavy quarks are quantified using the heavy quark expansion. Also taken into account are contributions from the 1-loop $Z^\pr…
Direct and Indirect searches for DM-electron interactions in sub-GeV DM models
Laboratoire de Physique Théorique et Hautes Énergies (LPTHE) \ https://ror.org/02mph9k76 , CNRS \& Sorbonne Université, 4 Place Jussieu, Paris, France；Laboratoire de Physique Nucléaire et de Hautes Énergies (LPNHE) \ https://ror.org/01hg8p552 , Sorbonne Université, Université de Paris, CNRS-IN2P3, 4 Place Jussieu, Paris, France
We review scenarios in which the particles that account for the Dark Matter (DM) in the Universe interact only through their couplings with the Higgs sector of the theory, the so-called Higgs-portal models. In a first step, we use a general and model-independent approach in which the DM particles are singlets with spin $0,\frac12$ or $1$, and assume a minimal Higgs sector with the presence of only the Standard Model (SM) Higgs particle observed at the LHC. In a second step, we discuss non-minimal scenarios in which the spin-$\frac12$ DM particle is accompanied by additional lepton partners and…
We investigate the electroweak phase transition patterns for a recently proposed baryogenesis model with CP violation originated in the dark sector. The model includes a complex scalar singlet-Higgs boson portal, a $U(1)_l$ gauge lepton symmetry with a $Z^\prime$ gauge boson portal and a fermionic dark matter particle. We find a novel thermal history of the scalar sector, featuring a $Z_2$ breaking singlet vacuum in the early Universe driven by a dark Yukawa coupling, that induces a one-step strongly first order electroweak phase transition. We explore the parameter space that generates the ob…
In secluded dark sector scenario, the connection between the visible and the dark sector can be established through a portal coupling and its presence opens up the possibility of non-adiabatic evolution of the dark sector. To study the non-adiabatic evolution of the dark sector, we have considered a $U(1)_{L_μ- L_τ} \otimes U(1)_X$ extension of the standard model (SM). Here the dark sector is charged only under $U(1)_X$ gauge symmetry whereas the SM fields are singlet under this symmetry. Due to the presence of tree-level kinetic mixing between $U(1)_X$ and $U(1)_{L_μ- L_τ}$ gauge bosons, the …
The weakly interacting massive particles (WIMPs) have been the most popular particle dark matter (DM) candidate for the last several decades, and it is well known that WIMP can be probed via the direct, indirect and collider experiments. However, the direct and indirect signals are highly suppressed in some scalar-mediated DM models, e.g. the lepton portal model with a Majorana DM candidate. As a result, collider searches are considered as the only hope to probe such models. In this white paper, we propose that the gravitational wave (GW) astronomy also serves as a powerful tool to probe such …
Dark matter particles may interact with other dark matter particles via a new force mediated by a dark photon, $A^{\prime}$, which would be the dark-sector analog to the ordinary photon of electromagnetism. The dark photon can obtain a highly suppressed mixing-induced coupling to the electromagnetic current, providing a portal through which dark photons can interact with ordinary matter. This review focuses on $A^{\prime}$ scenarios that are potentially accessible to accelerator-based experiments. We summarize the existing constraints placed by such experiments on dark photons, highlight what …
We study the experimental constraints on dark sector CP violation that enters the visible sector through a Higgs portal coupling $H^{\dagger} H Z^{\prime}_{μν} \widetilde Z^{\prime μν}$, where the $Z^{\prime}$ is from a new U(1) gauge symmetry which is assumed to couple to lepton number. We compute explicitly the leading two-loop contribution of this effective operator to the electron electric dipole moment (EDM) and show that the resulting constraints are comparable to those from direct $Z^{\prime}$ searches at electron-positron colliders when the effective operator is generated at tree level…
We revisit the possibility of a Dirac fermion dark matter candidate in the light of current $b \to s \ell^+ \ell^-$ anomalies by investigating a minimal extension of the Standard Model with a horizontal $\mathrm{U(1)}^{\prime}$ local symmetry. Dark matter stability is protected by a remnant $\mathcal{Z}_2$ symmetry arising after spontaneous symmetry breaking of $\mathrm{U(1)}^{\prime}$. The associated $Z^{\prime}$ gauge boson can accommodate current hints of new physics in $b \to s \ell^+ \ell^-$ decays, and acts as a vector portal between dark matter and the visible sector. We find that the m…
