arXiv subjects

Tianjun Li

Publications and source records attributed to Tianjun Li.

At least 73 records · Page 4Linked to original sources

arXiv2023

The hidden sector variations in the ${\cal N}=1$ supersymmetric three-family Pati-Salam models from intersecting D6-branes

It is well-known that three-family supersymmetric Pati-Salam models from intersecting D6-branes, where either one or both of the ${\rm U}(2)$ gauge factors are replaced by a ${\rm USp}(2)$ group, are quite scarce. In order to construct all such kind of models with generic additional gauge symmetries, we fix the observable sectors and study all the possible hidden sectors. Thus, we are able to completely determine all types of such kind of the inequivalent models on a $\mathbb{T}^6/(\mathbb{Z}_2\times \mathbb{Z}_2)$ orientifold from IIA string theory. We find the gauge coupling relations to be highly sensitive to the variations in the hidden sector. One of the models exhibits the gauge coupling unification for a particular solution at the string scale. In addition, we perform scan on the hidden sector variations for the models presented in arXiv:2112.09632, whose gauge coupling relations are still preserved. Thus, we fix the gap in the previous study and complete the model building for all the inequivalent models.

hep-th↗

arXiv2023

Revisit a realistic intersecting D6-brane with modified soft SUSY terms

Because there are a few typos in the supersymmetry breaking sfermion masses and trilinear soft term, regarding the current Large Hadron Collider (LHC) and dark matter searches, we revisit a three-family Pati-Salam model based on intersecting D6-branes in Type IIA string theory on a $\mathbf{T^6/(\Z_2\times \Z_2)}$ orientifold with a realistic phenomenology. We study the viable parameter space and discuss the spectrum consistent with the current LHC Supersymmetry searches along with the dark matter relic density bounds from the Planck 2018 data. For the gluinos and first two generations of sfermions, we observe that the gluino mass is in the range [2, 14] TeV, the squarks mass range is [2, 13] TeV and the sleptons mass is in the range [1, 5] TeV. We achieve the cold dark matter relic density consistent with 5$σ$ Planck 2018 bounds via A-funnel and coannihilation channels such as stop-neutralino, stau-neutralino, and chargino-neutralino. Except for a few chargino-neutralino coannihilation solutions, these solutions also satisfy current nucleon-neutralino spin-independent and spin-dependent scattering cross-sections and may be probed by future dark matter searches.

hep-ph↗

arXiv2023

The $Z$ resonance, inelastic dark matter, and new physics anomalies in the Simple Extension of the Standard Model (SESM) with general scalar potential

We consider the generic scalar potential with CP-violation, and study the $Z$ resonance and inelastic dark matter in the Simple Extension of the Standard Model (SESM), which can explain the dark matter as well as new physics anomalies such as the B physics anomalies and muon anomalous magnetic moment, etc. With the new scalar potential terms, we obtain the mass splittings for the real and imaginary parts of scalar fields. And thus we can have the DM co-annihilation process mediated by $Z$ boson, which couples exclusively to the CP-even and CP-odd parts of scalar fields. This is a brand new feature compared to the previous study. For the CP conserving case, we present the viable parameter space for the Higgs and $Z$ resonances, which can explain the B physics anomalies, muon anomalous magnetic moment, and dark matter relic density, as well as evade the constraint from the XENON1T direct detection simultaneously. For the CP-violating case, we consider the inelastic dark matter, and study four concrete scenarios for the inelastic DM-nucleon scatterings mediated by the Higgs and $Z$ bosons in details. Also, we present the benchmark points which satisfy the aforementioned constraints. Furthermore, we investigate the constraints from the dark matter-electron inelastic scattering processes mediated by the Higgs and $Z$ bosons in light of the XENONnT data. We show that the constraint on the $Z$ mediated process is weak, while the Higgs mediated process excludes the dark matter with mass around several MeV.

hep-ph↗

arXiv2023

A note on supergravity inflation in braneworld

We discuss supergravity inflation in braneworld cosmology for the class of potentials $V(ϕ)=αϕ^n\rm{exp}(-β^m ϕ^m)$ with $m=1,~2$. These minimal SUGRA models evade the $η$ problem due to a broken shift symmetry and can easily accommodate the observational constraints. In the high energy regime $V/λ\gg 1$, the numerical predictions and approximate analytic formulas are given for the scalar spectral index $n_s$ and tensor-to-scalar ratio $r$. The models with smaller $n$ are preferred while the models with larger $n$ are out of the $2σ$ region. Remarkably, the $ρ^2/λ$ correction to the energy density in Friedmann equation results in sub-Planckian inflaton excursions $Δϕ<1$.

hep-th↗

arXiv2023

Investigating the GmSUGRA in the MSSM through the long-lived bino NLSP at the HL-LHC

The axino, the supersymmetric partner of axion, is a well-motivated warm/hot dark matter candidate, and provides a natural solution to the relic density problem for the bino-like neutralino if it is the lightest supersymmetric particle (LSP). With the Generalized Minimal Supergravity, we study such kind of the viable parameter space where the bino-like neutralino is the next-to-LSP (NLSP) and the axino is the LSP. In addition, we consider a scenario where the bino is a long-lived NLSP with the lifetime varying from $10^{-6}$s to $10^{-4}$s, and then propose a new signal searching scheme involving one displaced photon together with the large missing transverse momentum at the HL-LHC. The bino-like lightest neutralino lies under or around 100 GeV and is produced as a decay product of the right-handed sleptons.The relevant axion coupling $f_a$ can be probed up to $\mathcal{O}(10^9)$ GeV at 2$σ$ level for the right-handed slepton mass under 300 GeV and the lightest neutralino mass under 100 GeV.

hep-ph↗

arXiv2023

String-scale Gauge Coupling Relations in the Supersymmetric Pati-Salam Models from Intersecting D6-branes

We have constructed all the three-family ${\cal N} = 1$ supersymmetric Pati-Salam models from intersecting D6-branes, and obtained 33 independent models in total. But how to realize the string-scale gauge coupling relations in these models is a big challenge. We first discuss how to decouple the exotic particles in these models. In addition, we consider the adjoint chiral mulitplets for $SU(4)_C$ and $SU(2)_L$ gauge symmetries, the Standard Model (SM) vector-like particles from D6-brane intersections, as well as the vector-like particles from the ${\cal N}=2$ subsector. We show that the gauge coupling relations at string scale can be achieved via two-loop renormalization group equation running for all these supersymmetric Pati-Salam models. Therefore, we propose a concrete way to obtain the string-scale gauge coupling realtions for the generic intersecting D-brane models.

hep-th↗

arXiv2023

Gaugino masses from misaligned supersymmetry breaking and R-symmetry breaking spurions

In gauge mediation models with multiple spurion fields breaking SUSY and the R-symmetry separately, we show that it is possible to generate gaugino masses at one loop if the R-charge arrangement satisfies a certain condition. The resulting gaugino masses are calculated and suppressed by some power of the messenger mass scale. We present two simple examples to demonstrate this possibility, and discuss possible phenomenology implications.

hep-ph↗

arXiv2022

Lepton Number Violating Electron Recoils in a $U(1)_{B-L}$ Model with Non-Standard Interactions

We propose an $SU(3)_C\times SU(2)_L\times U(1)_{Y}\times U(1)_{B-L}$ model, in which the neutrino masses and mixings can be generated via Type-I seesaw mechanism after $U(1)_{B-L}$ breaking. A light mediator emerges and enables non-standard interaction that violates the lepton number. We show that the non-standard neutrino interaction emerges in this model, and it can lead to low energy recoil events with the solar neutrino flux. Analyses are performed with the keV range electron recoil events at recent direct detection experiments, including XENON1T, PANDAX and XENONnT. Recent direct detection observations lead to upper bound on the combined coupling strength to electron and neutrino to $\sqrt{y'_νy_e} < 0.5 \times 10^{-6}$.

hep-ph↗

arXiv2022

Non-standard neutrino interactions in light mediator models at reactor experiments

Compared to other neutrino sources, the huge anti-neutrino fluxes at nuclear reactor based experiments empower us to derive stronger bounds on non-standard interactions of neutrinos with electrons mediated by light scalar/vector mediators. At neutrino energy around $200$~keV reactor anti-neutrino flux is at least an order of magnitude larger compared to the solar flux. The atomic and crystal form factors of the detector materials related to the details of the atomic structure becomes relevant at this energy scale as the momentum transfers would be small. Non-standard neutrino-electron interaction mediated by light scalar/vector mediator arises naturally in many low-scale models. We also propose one such new model with a light scalar mediator. Here, we investigate the parameter space of such low-scale models in reactor based neutrino experiments with low threshold Ge and Si detectors, and find the prospect of probing/ruling out the relevant parameter space by finding the projected sensitivity at $90 \%$ confidence level by performing a $χ^2$-analysis. We find that a detector capable of discriminating between electron recoil and nuclear recoil signal down to a very low threshold such as $5$~eV placed in reactor based experiment would be able to probe a larger region in parameter space compared to the previously explored region. A Ge (Si) detector with $10$~kg-yr exposure and 1 MW reactor anti-neutrino flux would be able to probe the scalar and vector mediators with masses below 1 keV for coupling products $\sqrt{g_νg_e}$ $\sim$ $1 \times 10^{-6}~(9.5 \times 10^{-7})$ and $1\times 10^{-7} ~(8\times 10^{-8})$, respectively.

hep-ph↗

arXiv2022

The Generic $U(1)_X$ Models Inspired from $SO(10)$

We propose the family universal $U(1)_X$ models with three right-handed neutrinos by choosing the $U(1)_X$ gauge symmetry as a linear combination of $U(1)_Y\times U(1)_χ$ of $SO(10)$. To be consistent with the quantum gravity effects, we introduced a Dirac fermion $χ$ as a dark matter candidate, which is odd under the gauged $Z_2$ symmetry after $U(1)_X$ breaking. The isospin violation dark matter with $f_n/f_p = -0.7$ can be realized naturally, and thus the LUX, PANDAX, and XENON1T experimental constraints can be evaded. Moreover, we study the masses and mixings for Higgs and gauge bosons, consider the LHC constraints on the $Z'$ mass, simulate various constraints from dark matter direct and indirect detection experiments, and then present the viable parameter spaces. To study the LHC $Z'$ mass bounds on the generic $U(1)_X$ models, we considered four kinds of scenarios, where scenario II with zero $U(1)_X$ charge for right-handed up-type quarks can relax the LHC $Z'$ mass bound a little bit.

hep-ph↗

arXiv2022

The Supersymmetry Breaking Soft Terms, and Fermion Masses and Mixings in the Supersymmetric Pati-Salam Model from Intersecting D6-branes

A supersymmetric Pati-Salam model with wrapping number equal to 5 has been constructed in Type IIA orientifolds on $\mathbf{T}^6/(\mathbb{Z}_2\times \mathbb{Z}_2)$ with intersecting D6-branes recently. In particular, the string-scale gauge coupling unification can be achieved due to the intermediate-scale vector-like particles from $\mathcal{N}=2$ sector. We calculate the supersymmetry breaking soft terms, and study the Standard Model (SM) fermion masses and mixings. There are nine pairs of Higgs doublets from $\mathcal{N}=2$ sector. Interestingly, we can explain the SM quark masses and mixings, as well as the charged leptons masses from three point and four-point Yukawa interactions. Moreover, we calculate the supersymmetry breaking soft terms in a previous model with gauge coupling unification since we find a typo in the previous study.

hep-th↗

arXiv2022

Probing the Supersymmetric Grand Unified Theories with Gravity Mediation at the Future Proton-Proton Colliders and Hyper-Kamiokande Experiment

With the grand desert hypothesis, we have proposed to probe the supersymmetric Grand Unified Theories (GUTs) at the future proton-proton (pp) colliders and Hyper-Kamiokande experiment previously. In this paper, we study the supersymmetric GUTs with gravity mediated supersymmetry breaking in details. First, considering the dimension-six proton decay via heavy gauge boson exchange, we point out that we can probe the supersymmetric GUTs with GUT scale $M_{GUT}$ up to $1.778\times 10^{16}$ GeV at the Hyper-Kamiokande experiment. Second, for the supersymmetric GUTs with $M_{GUT} \ge 1.0\times 10^{16}$ GeV and $M_{GUT} \ge 1.2\times 10^{16}$ GeV, we show that the upper bounds on the universal gaugino mass are $7.2$ TeV and 3.5 TeV, respectively, and thus the corresponding upper bounds on gluino mass are 15 TeV and 8 TeV, respectively. Also, we shall study the masses for charginos, neutralinos, squarks, sleptons, and Higgs particles in details. In particular, the supersymmetric GUTs with $M_{GUT} \leq 1.2\times 10^{16}$ GeV can be probed at the Hyper-Kamiokande experiment, and the supersymmetric GUTs with $M_{GUT}\ge 1.2\times 10^{16}$ GeV can be probed at the future 100 TeV pp collider experiments such as the ${\rm FCC}_{\rm hh}$ and SppC via gluino searches. Thus, the supersymmetric GUTs with gravity mediation can be probed by the ${\rm FCC}_{\rm hh}$, SppC, and Hyper-Kamiokande experiments. In our previous study, we have shown that the supersymmetric GUTs with anomaly and gauge mediated supersymmetry breakings are well within the reaches of these experiments. Therefore, our proposal provides the concrete scientific goal for the ${\rm FCC}_{\rm hh}$, SppC, and Hyper-Kamiokande experiments: probing the supersymmetric GUTs.

hep-ph↗

arXiv2022

Generic no-scale inflation inspired from string theory compactifications

We propose the generic no-scale inflation inspired from string theory compactifications. We consider the Kähler potentials with an inflaton field $φ$, as well as one, two, and three Kähler moduli. Also, we consider the renormalizable superpotential of $φ$ in general. We study the spectral index and tensor-to-scalar ratio in details, and find the viable parameter spaces which are consistent with the Planck and BICEP/Keck experimental data on the cosmic microwave background (CMB). The spectral index is $n_s\simeq 1-2/N \sim 0.965$ for all models, and the tensor-to-scalar ratio $r$ is $r\simeq12/N^2$, $ 83/N^4$ and $ 4/N^2$ for the one, two and three moduli models, respectively. The particular $r$ for two moduli model comes from the contributions of the non-negligible higher order term in potential. In the three moduli model, the scalar potential is similar to the global supersymmetry, but the Kähler potential is different. The E-model with $α=1$ and T-model with $α=1/3$ can be realized in the one modulus model and the three moduli model, respectively. Interestingly, the models with quadratic and quartic potentials still satisfy the current tight bound on $r$ after embedding into no-scale supergravity.

hep-ph↗

arXiv2022

The Final Model Building for the Supersymmetric Pati-Salam Models from Intersecting D6-Branes

All the possible three-family ${\cal N}=1$ supersymmetric Pati-Salam models constructed with intersecting D6-branes from Type IIA orientifolds on $T^6/(\mathbb{Z}_2\times \mathbb{Z}_2)$ are recently presented in arXiv: 2112.09632. Taking models with largest wrapping number $5$ and approximate gauge coupling unification at GUT scale as examples, we show string scale gauge coupling unification can be realized through two-loop renormalization group equation running by introducing seven pairs of vector-like particles from ${\cal N}=2$ sector. The number of these introduced vector-like particles are fully determined by the brane intersection numbers while there are two D6-brane parallel to each other along one two-torus. We expect this will solve the gauge coupling unification problem in the generic intersecting brane worlds by introducing vector-like particles that naturally included in the ${\cal N}=2$ sector.

hep-th↗

arXiv2022

The Minimal UV-induced Effective QCD Axion Theory

The characteristic axion couplings could be generated via effective couplings between the Standard Model (SM) fermions to a pseudo-Goldstone from a high-scale $U(1)$ Peccei-Quinn (PQ) symmetry breaking. Assuming that the UV-induced effective operators generate necessary couplings before the PQ symmetry breaking, and any low-scale couplings to the SM are restricted to the Yukawa sector, three minimal natural scenarios can be formulated, which provides a connection between the QCD-axions and mediators at the GUT/string scales. We find that the PQ symmetry breaking scale could be about $10^{15}$ GeV, higher than the classical QCD dark matter axion window but possible if the anthropic window is considered. We also propose an experiment to probe such scenarios. If the dark matter axion is discovered, they might suggest that we live in an atypical Hubble volume.

hep-ph↗

arXiv2022

Nuclear phase retrieval spectroscopy using resonant x-ray scattering

Light-matter interaction is exploited in spectroscopic techniques to access information about molecular, atomic or nuclear constituents of the sample of interest. While scattered light carries both amplitude and phase information of the electromagnetic field, most of the time the latter is lost in intensity measurements. However, often the phase information is paramount to reconstruct the desired information of the target, as it is well known from coherent x-ray imaging. Here we introduce a new phase retrieval algorithm which allows us to reconstruct the field phase information from two-dimensional time- and energy-resolved spectra. We apply this method to the particular case of x-ray scattering off Mössbauer nuclei at a synchrotron radiation source. Knowledge of the phase allows also for an excellent reconstruction of the energy spectra from experimental data, which could not be achieved with this resolution otherwise. Our approach provides an efficient novel data analysis tool which will benefit x-ray quantum optics and Mössbauer spectroscopy with synchrotron radiation alike.

physics.ins-det↗

arXiv2022

Four-Family ${\cal N}=1$ Supersymmetric Pati-Salam Models from Intersecting D6-Branes

We investigate the construction of four-family ${\cal N}=1$ supersymmetric Pati-Salam models from Type IIA $\mathbb{T}^6/(\mathbb{Z}_2 \times \mathbb{Z}_2)$ orientifold with intersecting D6-branes. Utilizing the deterministic algorithm introduced in Ref. \cite{heCompleteSearchSupersymmetric2021}, we obtain $274$ types of models with three rectangular tori and distinct gauge coupling relations at string scale, while $6$ types of models with two rectangular tori and one titled torus. In both cases, there exists a class of models with gauge coupling unification at string scale. In particular, for the models with two rectangular tori, one tilted torus and gauge coupling unification, the gaugino condensations are allowed, and thus supersymmetry breaking and moduli stabilization are possible for further phenomenological study.

hep-th↗

arXiv2022

Probing Relatively Heavier Right-Handed Selectron at the CEPC, $\rm\bf {FCC_{ee}}$ and ILC

We employ the low energy Minimal Supersymmetric Standard Model (MSSM) to explore the parameter space associated with $Z$-pole and Higgs-pole solutions. Such parameter spaces can not only saturate the cold dark matter relic density bound within 5$σ$ set by the Planck 2018, but also satisfy the other standard collider mass bounds and B-physics bounds. In particular, we show that the right-handed selectron can be light. Thus, we propose a search for the relatively heavier right-handed selectron at the future lepton colliders with the center-of-mass energy $\sqrt{s}=240$ GeV and integrated luminosity 3000 $\rm{fb^{-1}}$ via mono-photon channel: $e^{+}_{R} e^{-}_{R}\rightarrow {\tilde χ_{1}^{0}(bino)}+{\tilde χ_{1}^{0}(bino)}+γ$. We show that for the $Z$-pole case the right-handed selectron will be excluded up to 180 GeV and 210 GeV respectively at 3$σ$ and 2$σ$, while the right-handed selectron will be excluded up to 140 GeV and 180 GeV respectively at 3$σ$ and 2$σ$ in case of Higgs-pole.

hep-ph↗