Extra Gauge Bosons Research Articles

Heavy neutrino as dark matter in a neutrinophilic U(1) model

We study the prospect of heavy singlet neutrinos as a dark matter (DM) candidate within a neutrinophilic U(1) model, where the Standard Model (SM) is extended with a U(1) gauge symmetry, and neutrino mass and oscillation parameters are explained through an inverse see-saw mechanism. The lightest of the heavy neutrinos plays the role of the DM, while the newly introduced scalars and the extra gauge boson Z′\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$Z'$$\\end{document} act as mediators between the dark sector and the SM sector. We show the range of model parameters where this DM candidate can be accommodated in the Weakly Interacting Massive Particle (WIMP) or Feebly Interacting Massive Particle (FIMP) scenario. The observed DM relic density (DMRD) is achieved via the new gauge boson and singlet scalar portals in the WIMP scenario, whereas within the FIMP scenario, these two particles assume a distinct yet pivotal role in generating the observed DMRD.

Electroweak superpartner production at 13.6 Tev with Resummino

Due to the greater experimental precision expected from the currently ongoing LHC Run 3, equally accurate theoretical predictions are essential. We update the documentation of the Resummino package, a program dedicated to precision cross section calculations for the production of a pair of sleptons, electroweakinos, and leptons in the presence of extra gauge bosons, and for the production of an associated electroweakino-squark or electroweakino-gluino pair. We detail different additions that have been released since the initial version of the program a decade ago, and then use the code to investigate the impact of threshold resummation corrections at the next-to-next-to-leading-logarithmic accuracy. As an illustration of the code we consider the production of pairs of electroweakinos and sleptons at the LHC for centre-of-mass energies ranging up to 13.6 TeV and in simplified model scenarios. We find slightly increased total cross section values, accompanied by a significant decrease of the associated theoretical uncertainties. Furthermore, we explore the dependence of the results on the squark masses.

Z boson mixing and the mass of the W boson

We explore the possibility of explaining the $W$ boson mass with an extra gauge boson mixing with the $Z$ boson at tree level. Extra boson mixing with the $Z$ boson will change the expression of the $Z$ boson mass, thus altering the $W$ boson mass. We explore two models in this work. We find that in the Derivative Portal Dark Matter model, there are parameters space which can give the observed $W$ boson mass, as well as the observed Dark Matter relic density. These parameters space can also fulfill the constraints from the electroweak oblique parameters and Dark Matter indirect detection. In the U(1) extension model, the kinetic mixing between extra boson and $B$ boson can also give the observed $W$ boson mass. However, to fulfill electroweak oblique parameters fit the kinetic mixing in the U(1) model can only contribute about $27~\mathrm{MeV}$ extra mass to the Standard Model $W$ boson mass. Both models indicate the extra vector boson with the best fit mass around $120~\mathrm{GeV}$.

Charged-current non-standard neutrino interactions at the LHC and HL-LHC* *Supported by the National Natural Science Foundation of China (11875157, 12147214), the Natural Science Foundation of the Liaoning Scientific Committee (LJKZ0978), and the Outstanding Research Cultivation Program of Liaoning Normal University (21GDL004).

A series of new physics scenarios predict the existence of the extra charged gauge boson , which can induce charged-current (CC) non-standard neutrino interactions (NSIs). The theoretical constraints on the simplified model and further on the CC NSI parameters from partial wave unitarity and decays are considered. The sensitivity of the process to the model at the LHC and high-luminosity (HL) LHC experiments is investigated by estimating the expected constraints on ( or μ) using a Monte-Carlo (MC) simulation. We find that the interference effect plays an important role, and the LHC can strongly constrain . Compared with those at the LHC with , the expected constraints at the LHC with can be strengthened to approximately one order of magnitude.

Revisiting sterile neutrino dark matter in gauged U(1)B−L model

We reexamine sterile neutrino dark matter in gauged $U(1)_{B-L}$ model. Improvements have been made by tracing and careful evaluation of the evolution of the number densities of sterile neutrinos $N$ and extra neutral gauge bosons $Z'$. As a result, the cosmologically-interesting gauge coupling of $U(1)_{B-L}$ for freeze-in sterile neutrinos turns out to be smaller than the values reported in the literature. This avoids the overproduction of $Z'$ so that it is consistent with the big bang nucleosynthesis and the cosmic microwave background constraints on the effective number of neutrino species. Similarly, the free-streaming length constraints exclude a large parameter space derived in previous studies. In addition to known freeze-in pair production of $N$ from the standard model fermion pairs, we find the case that $N$ is dominantly produced from a pair of $Z'$ at the temperature characterized by the $B-L$ breaking scalar mass. Thus, the naive truncation of the $U(1)_{B-L}$ scalar contribution made in the literature is not valid.

Phenomenology of an E6 inspired extension of the Standard Model: Higgs sector

We investigate a variant of the left-right symmetric model based on the $SU(3{)}_{C}\ensuremath{\bigotimes}SU(2{)}_{L}\ensuremath{\bigotimes}U(1{)}_{L}\ensuremath{\bigotimes}SU(2{)}_{R}\ensuremath{\bigotimes}U(1{)}_{R}$ gauge group (32121). Spontaneously breaking of 32121 down to the Standard Model (SM) gauge group requires a bidoublet under $SU(2{)}_{L}\ensuremath{\bigotimes}SU(2{)}_{R}$, a right-handed doublet scalar under $SU(2{)}_{R}$, along with a $SU(2)$ singlet scalar boson. Symmetry breaking leads to several neutral and charged massive gauge bosons apart from the SM $W$ and $Z$. The Large Hadron Collider (LHC) results for the search of heavy gauge bosons can be used to constrain the vacuum expectation values responsible for giving masses to these extra heavy gauge bosons. The physical spectrum of the scalar bosons contains several neutral $CP$-even and $CP$-odd states and a couple of charged scalars apart from the SM-like Higgs boson. We have put constraints on the masses of some of these scalars from the existing LHC data. The possible decay rates and production cross sections of these scalars have been investigated in some detail. Production cross sections for some of the scalars look promising at the 14 and 27 TeV runs of the LHC with the high luminosity option. We keep, in our model, all the fermions present in the 27-dimensional fundamental representation of ${E}_{6}$. Mass limit of one such exotic lepton has also been derived from present LHC data. It is noted that some of these neutral exotic lepton or neutral scalar bosons of this model can serve the purpose of cold dark matter.

Scale-invariant quadratic gravity and inflation in the Palatini formalism

In the framework of classical scale invariance, we consider quadratic gravity in the Palatini formalism and investigate the inflationary predictions of the theory. Our model corresponds to a two-field scalar-tensor theory, which involves the Higgs field and an extra scalar field stemming from a gauge $U(1{)}_{X}$ extension of the Standard Model, which contains an extra gauge boson and three right-handed neutrinos. Both scalar fields couple nonminimally to gravity and induce the Planck scale dynamically, once they develop vacuum expectation values. By means of the Gildener-Weinberg approach, we describe the inflationary dynamics in terms of a single scalar degree of freedom along the flat direction of the tree-level potential. The one-loop effective potential in the Einstein frame exhibits plateaus on both sides of the minimum and thus the model can accommodate both small and large field inflation. The inflationary predictions of the model are found to comply with the latest bounds set by the Planck collaboration for a wide range of parameters and the effect of the quadratic in curvature terms is to reduce the value of the tensor-to-scalar ratio.

Explaining Xenon-1T signal with FIMP dark matter and neutrino mass in a U(1)_{X} extension

In the present work, we have extended the standard model by an abelian U(1)_{X} gauge group and additional particles. In particular, we have extended the particle content by three right handed neutrinos, two singlet scalars and two vectors like leptons. Charged assignments under different gauge groups are such that the model is gauge anomaly free and the anomaly contributions cancel among generations. Once the symmetry gets broken then three physical Higgses are produced, one axion like particle (ALP), which also acts as the keV scale FIMP dark matter is produced and the remaining component is absorbed by the extra gauge boson. Firstly, we have successfully generated neutrino mass by the type-I seesaw mechanism for normal hierarchy with the 3sigma bound on the oscillation parameters. The ALP in the present model can explain the Xenon-1T electron recoil signal at keV scale through its coupling with the electron. We have shown that ALP can be produced from the right handed neutrino decay through the freeze in mechanism. Electron and tauon get masses from dimensional-5 operators at the Planck scale and if we consider the vevs v_{1,2} simeq 10^{12} GeV then we can obtain the correct value of the electron mass but not the tauon mass. The vector like leptons help in getting the correct value of the tauon mass through another higher dimensional operator which also has a role in DM production by the 2 rightarrow 2 process, giving the correct ballpark value of relic density for suitable reheat temperature of the Universe. We have shown that the ALP production by the higher dimensional operator can explain the electron, tauon mass and Xenon-1T signal simultaneously whereas the decay production can not explain all of them together.

Extra gauge bosons and lepton flavor universality violation in ϒ and B meson decays

Lepton flavor universality can be tested through the ratio of semileptonic $B$ meson decays and leptonic $\mathrm{\ensuremath{\Upsilon}}$ meson decays, with $\mathrm{\ensuremath{\Upsilon}}\ensuremath{\equiv}\mathrm{\ensuremath{\Upsilon}}(nS)$ ($n=1$, 2, 3). For the charged-current transitions $b\ensuremath{\rightarrow}c\ensuremath{\tau}{\overline{\ensuremath{\nu}}}_{\ensuremath{\tau}}$, discrepancies between the experiment and the Standard Model (SM) have been observed in recent years by different flavor facilities such as BABAR, Belle, and LHCb. While for the neutral-current transitions $b\overline{b}\ensuremath{\rightarrow}\ensuremath{\tau}\overline{\ensuremath{\tau}}$, the BABAR experiment reported recently a new measurement of leptonic decay ratio ${R}_{\mathrm{\ensuremath{\Upsilon}}(3S)}=\mathrm{BR}(\mathrm{\ensuremath{\Upsilon}}(3S)\ensuremath{\rightarrow}\phantom{\rule{0ex}{0ex}}{\ensuremath{\tau}}^{+}{\ensuremath{\tau}}^{\ensuremath{-}})/\mathrm{BR}(\mathrm{\ensuremath{\Upsilon}}(3S)\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}})$, showing an agreement with the SM at the $1.8\ensuremath{\sigma}$ level. In light of this new BABAR result and regarding the connection between new physics (NP) interpretations to the charged-current $b\ensuremath{\rightarrow}c\ensuremath{\tau}{\overline{\ensuremath{\nu}}}_{\ensuremath{\tau}}$ anomalies and neutral-current $b\overline{b}\ensuremath{\rightarrow}\ensuremath{\tau}\overline{\ensuremath{\tau}}$ processes, in this study, we revisit the NP consequences of this measurement within a simplified model with extra massive gauge bosons that coupled predominantly to left-handed leptons of the third generation. We show that the BABAR measurement of ${R}_{\mathrm{\ensuremath{\Upsilon}}(3S)}$ cannot easily be accommodated (within its experimental $1\ensuremath{\sigma}$ range) together with the other $b\ensuremath{\rightarrow}c\ensuremath{\tau}{\overline{\ensuremath{\nu}}}_{\ensuremath{\tau}}$ data, hinting toward a new anomalous observable.

Contributions to ZZV^* (V=gamma ,Z,Z') couplings from CP violating flavor changing couplings

The one-loop contributions to the trilinear neutral gauge boson couplings ZZV^* (V=gamma ,Z,Z'), parametrized in terms of one CP-conserving f_5^{V} and one CP-violating f_4^{V} form factors, are calculated in models with CP-violating flavor changing neutral current couplings mediated by the Z gauge boson and an extra neutral gauge boson Z'. Analytical results are presented in terms of Passarino-Veltman scalar functions. Constraints on the vector and axial couplings of the Z gauge boson left| g_{{VZ}}^{tu}right| < 0.0096 and left| g_{{VZ}}^{tc}right| <0.011 are obtained from the current experimental data on the trightarrow Z q decays. It is found that in the case of the ZZgamma ^* vertex the only non-vanishing form factor is f_5^{gamma }, which can be of the order of 10^{-3}, whereas for the ZZZ^* vertex both form factors f_5^{Z} and f_4^{Z} are non-vanishing and can be of the order of 10^{-6} and 10^{-5}, respectively. Our estimates for f_5^{gamma } and f_5^{Z} are smaller than those predicted by the standard model, where f_4^{Z} is absent up to the one loop level. We also estimate the ZZ{Z'}^{*} form factors arising from both diagonal and non-diagonal Z' couplings within a few extension models. It is found that in the diagonal case f_{5}^{Z'} is the only non-vanishing form factor and its real and imaginary parts can be of the order of 10^{-1}–10^{-2} and 10^{-2}–10^{-3}, respectively, with the dominant contributions arising from the light quarks and leptons. In the non-diagonal case f_{5}^{Z^prime } can be of the order of 10^{-4}, whereas f_4^{Z'} can reach values as large as 10^{-7}–10^{-8}, with the largest contributions arising from the Z'tq couplings.

Constraints on the charged-current non-standard neutrino interactions induced by the gauge boson W′

Many new physics scenarios predict the existence of the extra charged gauge boson W′, which can induce the charged-current (CC) non-standard neutrino interactions (NSI). We investigate the constraints on the CC NSI in model-independent fashion via considering the W′ contributions to the lepton flavor violating (LFV) decays ℓi→ℓjγ, the pure leptonic flavor conservation (FC) decays ℓi→ℓjνiνj¯, leptonic decays of charged pion meson, semileptonic τ decays, and superallowed β decays. We find that the constraints on the pure leptonic CC NSI are generally stronger than the ones for the CC NSI with first generation quarks. The most stringent constraints on the CC NSI arise from the LFV decay μ→eγ. The constraints on the CC NSI from direct searches at the LHC are also discussed.

Anomaly Cancellation with an Extra Gauge Boson.

Many extensions of the standard model include an extra gauge boson, whose couplings to fermions are constrained by the requirement that anomalies cancel. We find a general solution to the resulting diophantine equations in the plausible case where the chiral fermion content is that of the standard model plus three right-handed neutrinos.

Singlet fermionic dark matter with dark Z

We present a fermionic dark matter model mediated by the hidden gauge boson. We assume the QED-like hidden sector which consists of a Dirac fermion and U(1)_X gauge symmetry, and introduce an additional scalar electroweak doublet field with the U(1)_X charge as a mediator. The hidden U(1)_X symmetry is spontaneously broken by the electroweak symmetry breaking and there exists a massive extra neutral gauge boson in this model which is the mediator between the hidden and visible sectors. Due to the U(1)_X charge, the additional scalar doublet does not couple to the Standard Model fermions, which leads to the Higgs sector of type I two Higgs doublet model. The new gauge boson couples to the Standard Model fermions with couplings proportional to those of the ordinary Z boson but very suppressed, thus we call it the dark Z boson. We study the phenomenology of the dark Z boson and the Higgs sector, and show the hidden fermion can be the dark matter candidate.

Probing new neutral gauge bosons with CEνNS and neutrino-electron scattering

The potential for probing extra neutral gauge boson mediators ($Z^\prime$) from low-energy measurements is comprehensively explored. Our study mainly focuses on $Z^\prime$ mediators present in string-inspired $E_6$ models and left-right symmetry. We estimate the sensitivities of coherent-elastic neutrino-nucleus scattering (CE$\nu$NS) and neutrino-electron scattering experiments. Our results indicate that such low-energy high-intensity measurements can provide a valuable probe, complementary to high-energy collider searches and electroweak precision measurements.

Dark matter mass from relic abundance, an extra U(1) gauge boson, and active-sterile neutrino mixing

In a model with an extra $U(1)$ gauge to SM gauge group, we have shown the allowed region of masses of extra gauge boson and the dark matter which is the lightest one among other right-handed Majorana fermions present in the model. To obtain this region, we have used bounds coming from constraints on active-sterile neutrino masses and mixing from various oscillation experiments, constraint on dark matter relic density obtained by PLANCK together with the constraint on the extra gauge boson mass and its gauge coupling recently obtained by ATLAS Collaboration at LHC. From the allowed regions, it is possible to get some lower bounds on the masses of the extra gauge boson and the dark matter and considering those values it is possible to infer what could be the spontaneous symmetry breaking scale of an extra $U(1)$ gauge symmetry.

Dirac neutrino mass generation from a Majorana messenger

The radiative type-I seesaw has been already implemented to explain the lightness of Majorana neutrinos with both Majorana and Dirac heavy fermions, and the lightness of Dirac neutrinos with Dirac heavy fermions. In this work we present a minimal implementation of the radiative type-I seesaw with light Dirac neutrinos and heavy Majorana fermions. An inert doublet and a complex singlet scalar complete the dark sector which is protected by an Abelian fermiophobic gauge symmetry that also forbids tree level mass contributions for the full set of light neutrinos. A fermion vector-like extension of the model is also proposed where the light right-handed neutrinos can thermalize in the primordial plasma and the extra gauge boson can be directly produced at colliders. In particular, the current upper bound on $\Delta N_{\text{eff}}$ reported by PLANCK points to large ratios $M_{Z'}/g'\gtrsim 40\ \text{TeV}$ which can be competitive with collider constraint for $g'$ sufficiently large in the ballpark of the Standard Model values, while future cosmic microwave background experiments may probe all the no minimal models presented here.

Constraints on Nonstandard Neutrino Interaction from Neutrino Electron Scattering

Neutrino-electron scattering is a purely leptonic fundamental interaction and therefore provides an important channel to test the Standard Model (SM), especially at the low energy-momentum transfer regime [1, 2]. In this study Data on and ve − e scattering from the TEXONO and LSND experiments, respectively, are used and constraints on neutrino Non-Stardard-Interactions (NSI) couplings depending on model-independent approaches, which are described by a four-Fermi point like interaction and depending on several beyond-Standard-Model-physics scenarios, mediated by massive intermediate particles including (1) an extra Z-prime gauge boson, (2) a new light spin-1 boson (NLS1B), (3) Dark Photon (DP), and (4) a charged Higgs boson (CHB), are placed via the neutrino-electron scattering channel to test the SM at a low energy-momentum transfer regime. The relevant parameter spaces are extended by allowing light mediators.

Constraining heavy neutral gauge boson Z′ in the 3 - 3 - 1 models by weak charge data of Cesium and proton

The recent experimental data of the weak charges of Cesium and proton is analyzed in the framework of the models based on the SU(3)C×SU(3)L×U(1)X (3-3-1) gauge group, including the 3-3-1 model with CKS mechanism (3-3-1CKS) and the general 3-3-1 models with arbitrary β (3-3-1β) with three Higgs triplets. We will show that at the TeV scale, the mixing among neutral gauge bosons plays significant effect. Within the present values of the weak charges of Cesium and proton we get the lowest mass bound of the extra heavy neutral gauge boson to be 1.27 TeV. The results derived from the weak charge data, perturbative limit of Yukawa coupling of the top quark, and the relevant Landau poles favor the models with β=±13 and β=0 while ruling out the ones with β=±3. In addition, there are some hints showing that in the 3-3-1 models, the third quark family should be treated differently from the first twos.

A very heavy sneutrino as viable thermal dark matter candidate in U(1)\u2032 extensions of the MSSM

We study the Standard Model singlet (“right-handed”) sneutrino {tilde{nu}}_R dark matter in a class of U(1)′ extensions of the MSSM that originate from the breaking of the E6 gauge group. These models, which are referred to as UMSSM, contain three right-handed neutrino superfields plus an extra gauge boson Z′ and an additional SM singlet Higgs with mass ≃ MZ′, together with their superpartners. In the UMSSM the right sneutrino is charged under the extra U(1)′ gauge symmetry; it can therefore annihilate via gauge interactions. In particular, for {M}_{{tilde{nu}}_R}simeq {M}_{Zprime }/2 the sneutrinos can annihilate by the exchange of (nearly) on-shell gauge or Higgs bosons. We focus on this region of parameter space. For some charge assignment we find viable thermal {tilde{nu}}_R dark matter for mass up to ∼ 43 TeV. This is the highest mass of a good thermal dark matter candidate in standard cosmology that has so far been found in an explicit model. Our result can also be applied to other models of spin−0 dark matter candidates annihilating through the resonant exchange of a scalar particle. These models cannot be tested at the LHC, nor in present or near-future direct detection experiments, but could lead to visible indirect detection signals in future Cherenkov telescopes.

Phenomenology of two texture zero neutrino mass in left-right symmetric model with Z8 \xd7 Z2

We have done a phenomenological study on the neutrino mass matrix Mν favoring two zero texture in the framework of left-right symmetric model (LRSM) where type I and type II seesaw naturally occurs. The type I SS mass term is considered to be following a trimaximal mixing (TM) pattern. The symmetry realizations of these texture zero structures has been realized using the discrete cyclic abelian Z8 × Z2 group in LRSM. We have studied six of the popular texture zero classes named as A1, A2, B1, B2, B3 and B4 favoured by neutrino oscillation data in our analysis. We basically focused on the implications of these texture zero mass matrices in low energy phenomenon like neutrinoless double beta decay (NDBD) and lepton flavour violation (LFV) in LRSM scenario. For NDBD, we have considered only the dominant new physics contribution coming from the diagrams containing purely RH current and another from the charged Higgs scalar while ignoring the contributions coming from the left-right gauge boson mixing and heavy light neutrino mixing. The mass of the extra gauge bosons and scalars has been considered to be of the order of TeV scale which is accessible at the colliders.