Supersymmetric Standard Model Research Articles

Explaining anomalies of B-physics, muon g-2 and W mass in R-parity violating MSSM with seesaw mechanism

The recent experimental results including R_{K^{(*)}}, R_{D^{(*)}}, (g-2)_mu and W mass show deviations from the standard model (SM) predictions, implying the clues of new physics (NP). In this work, we investigate the explanations of these anomalies in the R-parity violating minimal supersymmetric standard model (RPV-MSSM) extended with the inverse seesaw mechanism. The non-unitarity extent eta _{ee} and the loop corrections from the interaction lambda 'hat{L} hat{Q} hat{D} are utilized to raise the prediction of W mass through muon decays. We also find that the interaction lambda 'hat{L} hat{Q} hat{D} involved with right-handed (RH)/singlet (s)neutrinos can explain the R_{K^{(*)}} and R_{D^{(*)}} anomalies simultaneously when considering nonzero lambda '_{1jk}. For nonzero lambda '_{2jk}, this model fulfills the whole brightarrow sell ^+ell ^- fit but cannot be accordant with R_{D^{(*)}} measurements. The explanations in both cases are also favored by (g-2)_mu data, neutrino oscillation data and the relevant constraints we scrutinized. Furthermore, this model framework can be tested in future experiments covering, e.g., the predicted lepton flavor violations (LFV) at Belle II and the Future Circular Collider with e^+e^- beams (FCC-ee), as well as the heavy neutrinos at future colliders.

On the Suppression of the Dark Matter-Nucleon Scattering Cross Section in the SE6SSM

In the E6 inspired U(1)N extension of the minimal supersymmetric (SUSY) standard model (MSSM), a single discrete Z˜2H symmetry permits suppressing rapid proton decay and non-diagonal flavor transitions. If matter parity and Z˜2H symmetry are preserved in this SUSY model (SE6SSM), it may involve two dark matter candidates. In this article, we study a new modification of the SE6SSM in which the cold dark matter is composed of gravitino and the lightest neutral exotic fermion. We argue that, in this case, the dark matter nucleon scattering cross-section can be considerably smaller than the present experimental limit.

Z boson decays Z→li±lj∓ and Higgs boson decays h→li±lj∓ with lepton flavor violation in a U(1) extension of the MSSM

$U(1)_X$SSM is the extension of the minimal supersymmetric standard model (MSSM) and its local gauge group is $SU(3)_C\times SU(2)_L \times U(1)_Y \times U(1)_X$. We study lepton flavor violating (LFV) decays $Z\rightarrow{{l_i}^{\pm}{l_j}^{\mp}}$($Z\rightarrow e{\mu}$, $Z\rightarrow e{\tau}$, and $Z\rightarrow {\mu}{\tau}$) and $h\rightarrow{{l_i}^{\pm}{l_j}^{\mp}}$($h\rightarrow e{\mu}$, $h\rightarrow e{\tau}$, and $h\rightarrow {\mu}{\tau}$), in this model. In the numerical results, the branching ratios of $Z\rightarrow{{l_i}^{\pm}{l_j}^{\mp}}$ are from $10^{-9}$ to $10^{-13}$ and the branching ratios of $h\rightarrow{{l_i}^{\pm}{l_j}^{\mp}}$ are from $10^{-3}$ to $10^{-9}$, which can approach the present experimental upper bounds. Based on the latest experimental data, we analyze the influence of different sensitive parameters on the branching ratio, and make reasonable predictions for future experiments. The main sensitive parameters and LFV sources are the non-diagonal elements corresponding to the initial and final generations of leptons, which can be seen from the numerical analysis.

Three-loop β-functions and two-loop anomalous dimensions for MSSM regularized by higher covariant derivatives in an arbitrary supersymmetric subtraction scheme

Three-loop β-functions of the Minimal Supersymmetric Standard Model regularized by higher covariant derivatives are obtained for an arbitrary supersymmetric subtraction scheme. For this purpose we first calculate two-loop anomalous dimensions for all MSSM chiral matter superfields defined in terms of the bare couplings. Then we use the NSVZ equations for the renormalization group functions defined in terms of the bare couplings, which are valid in all orders in the case of using the higher covariant derivative regularization. This gives the three-loop β-functions defined in terms of the bare couplings. After that, we construct the three-loop β-functions and the two-loop anomalous dimensions standardly defined in terms of the renormalized couplings for an arbitrary subtraction scheme. As a nontrivial correctness test, we verify that for a certain renormalization prescription the general results reproduce the ones obtained earlier in the overline{mathrm{DR}} scheme. Also this can be considered as an indepedent confirmation of the overline{mathrm{DR}} results.

Deviations from tribimaximal and golden ratio mixings under radiative corrections of neutrino masses and mixings

The impact of renormalization group equations on neutrino masses and mixings at high-energy scales in the Minimal Supersymmetric Standard Model is studied using two different mixing patterns such as Tribimaximal (TBM) mixing and Golden Ratio (GR) mixing in consistent with cosmological bound of the sum of three neutrino masses, [Formula: see text]. Magnifications of neutrino masses and mixing angles at low-energy scales are obtained by giving proper input masses, and mixing angles from the TBM mixing matrix and GR mixing matrix at high-energy scales. High-energy scales, [Formula: see text] such as [Formula: see text], [Formula: see text], [Formula: see text] GeV are employed in the analysis. The large solar ([Formula: see text]) and atmospheric ([Formula: see text]) neutrino mixing angles with zero reactor angle ([Formula: see text]) from both TBM mixing matrix and GR mixing matrix at high scale, can magnify the reactor angle ([Formula: see text]) at low-energy scale in 3[Formula: see text] confidence level. Both cases of normal hierarchy and inverted hierarchy are addressed here. In a normal hierarchical case, it is found that [Formula: see text] and that in an inverted hierarchical case is [Formula: see text] in both mixing patterns. Possibility of [Formula: see text] or [Formula: see text] is observed at low scale. The analysis shows the validity of the two mixing patterns at a high-energy scale.

Deep learning jet images as a probe of light Higgsino dark matter at the LHC

A Higgsino in supersymmetric standard models can play the role of a dark matter particle. In conjunction with the naturalness criterion, the Higgsino mass parameter is expected to be around the electroweak scale. In this work, we explore the potential of probing the nearly degenerate light Higgsinos with machine learning at the LHC. By analyzing jet images and other jet substructure information, we use the convolutional neural network to enhance the signal significance. We find that our deep learning jet image method can improve the previous result based on the conventional cut flow by about a factor of 2 at the High-Luminosity LHC.

Higgs boson properties and supersymmetry: Constraints and sensitivity from the LHC to ane+e−collider

The study of the Higgs boson properties offers compelling perspectives for testing the effects of physics beyond the Standard Model and has deep implications for the LHC program and future colliders. Accurate determinations of the Higgs boson properties can provide us with a distinctively precise picture of the Higgs sector, set tight bounds, and predict ranges for the values of new physics model parameters. In this paper, we discuss the constraints on supersymmetry that can be derived by a determination of the Higgs boson mass and couplings. We quantify these constraints by using scans of the 19-parameter space of the so-called phenomenological minimal supersymmetric Standard Model. The fraction of scan points that can be excluded by the Higgs measurements is studied for the coupling measurement accuracies obtained in LHC run 2 and expected for the HL-LHC program and ${e}^{+}{e}^{\ensuremath{-}}$ colliders and contrasted with those derived from missing transverse energy searches at the LHC and from dark matter experiments.

Search for a massive scalar resonance decaying to a light scalar and a Higgs boson in the four b quarks final state with boosted topology

We search for new massive scalar particles X and Y through the resonant process X→YH→bb¯bb¯, where H is the standard model Higgs boson. Data from CERN LHC proton-proton collisions are used, collected at a centre-of-mass energy of 13 TeV in 2016–2018 and corresponding to an integrated luminosity of 138fb−1. The search is performed in mass ranges of 0.9–4 TeV for X and 60–600 GeV for Y, where both Y and H are reconstructed as Lorentz-boosted single large-area jets. The results are interpreted in the context of the next-to-minimal supersymmetric standard model and also in an extension of the standard model with two additional singlet scalar fields. The 95% confidence level upper limits for the production cross section vary between 0.1 and 150 fb depending on the X and Y masses, and represent a significant improvement over results from previous searches.

Realization of slow-roll inflation and the MSSM in supergravity theories with new Fayet-Iliopoulos terms

A new supergravity D-term, not associated to gauged R-symmetry, was recently discovered and used to construct new supergravity models. In this paper we use a generalization of the new D-term that we used in previous works, to construct a supergravity model of slow-roll inflation with the observable sector of the minimal supersymmetric standard model. Supersymmetry is broken at a high scale in the hidden sector and communicated to the observable sector by gravity mediation. The new D-term contains free parameters that can give large masses to scalar superpartners of quarks and leptons and to the higgsinos while holding the masses of observed particles fixed. Gauginos receive a mass from a noncanonical kinetic term for the vector supermultiplets. We also present a simple argument proving in full generality that the cutoff $\mathrm{\ensuremath{\Lambda}}$ of effective theories containing new D-terms can never exceed the supersymmetry breaking scale. In our theory, the relation between D-term and the Hubble constant during inflation also implies the universal relation $\mathrm{\ensuremath{\Lambda}}\ensuremath{\lesssim}\sqrt{H{M}_{\mathrm{Pl}}}$.

Investigating non-minimal flavour-violating CMSSM in the light of Higgs-Boson mass using information theory

Flavour-violating interactions of the stop-quarks are expected to provide an additional few GeV contributions to the Higgs-Boson mass, particularly when mix with scharm-quarks, thereby allowing reduced supersymmetry (SUSY) breaking scale compared to flavour-conserving constrained minimal supersymmetric Standard Model (CMSSM). Inspired by this, we analyse the interactions mentioned above in the context of CMSSM using the information entropy of the Higgs-Boson for a wider region of flavour-violating CMSSM parameter space (m0,m1/2,A0, tan⁡β,sgn(μ),δctij), where δctij represents the flavour-violating coupling of the top-quark with the charm-quark and i,j defining left and right chiralities of squarks. Our information-theoretic analysis of the model mentioned above reveals the most favourable values of (m0,m1/2,A0,tan⁡β,δctij) as (4.30TeV,2.32TeV,−4.96TeV, 22.8,0.037) and (4.16TeV, 3.89TeV,−4.10TeV,19.4,0.039) for (i,j)=(L,R) and (R,L), respectively, corresponding to the maximum entropy which suggest the SUSY breaking scale to be about 5 TeV, thereby allowing considerable low values of sparticles masses than the flavour-conserving CMSSM.

Dark Matter in Supersymmetry

Supersymmetry is a well-motivated theory for physics beyond the Standard Model. In particular, supersymmetric models can naturally possess dark matter candidates that can give rise to the measured dark matter content of the universe. We review several models that have been analyzed with regard to dark matter by groups based in Spain in recent years. These models include, in particular, the Minimal Supersymmetric Standard Model (MSSM) and the ‘μ from ν’ Supersymmetric Standard Model (μνSSM) in various versions.

The mass-degenerate SM-like Higgs and anomaly of (g − 2)μ in μ-term extended NMSSM

We chose the μ-term extended next-to-minimal supersymmetric standard model (μNMSSM) for this work, and we perform a phenomenological study based on the assumption that the observed Standard Model (SM)-like Higgs is explained by the presence of a double overlapping resonance and in light of the recent (g − 2)μ result. The study also takes into account a variety of experimental results, including Dark Matter (DM) direct detections and results from sparticle searches at the Large Hadron Collider (LHC). We study the properties of DM confronted with the limits from DM direct detections. As a second step, we focus our attention on the properties of the mass-degenerate SM-like Higgs bosons and on explaining the anomaly of (g −2)μ. We conclude that the anomaly of (g −2)μ can be explained in the scenario with two mass-degenerate SM-like Higgs, and there are samples that meet the current constraints and fit 1 − σ anomalies of Higgs data.

Associated production of heavy Higgs bosons with a mathrm{b}overline{mathrm{b}} pair in the nonholomorphic MSSM and LHC searches

In the NonHolomorphic Supersymmetric Standard Model (NHSSM), the Yukawa couplings of the bottom quark (yb) and the tau lepton (yτ) might receive substantial supersymmetric (SUSY) radiative corrections which have prominent dependencies on the NHSSM-specific trilinear soft parameters, {A}_b^{prime } and {A}_{tau}^{prime } , respectively, in addition to their well-known dependence on tan β as is already present in the Minimal SUSY Standard Model (MSSM). We study to what extent these could affect the production cross sections of the heavy Higgs bosons (H and A) in association with a pair of b-quarks and their decay branching ratios, in particular, to a tau overline{tau} pair and compare them with those obtained in the MSSM. Requiring compliance with the recently observed upper bounds on the product of their total cross section and the branching ratio to tau overline{tau} at the 13 TeV run of the Large Hadron Collider (LHC), with data worth 139 fb−1, results in an altered exclusion region in the customary mA− tan β plane in the framework of the NHSSM when compared to what is derived by the LHC experiments within an MSSM setup. Such alterations are estimated to be pronounced only for large tan β (≥ 40) and for large, negative {A}_b^{prime } when one finds a reinforced exclusion of the mA − tan β plane with an excluded mA value larger by ≈ 200 GeV, compared to the MSSM case, at tan β = 60. On the other hand, the maximum relaxation in mA, for a similarly large but positive {A}_b^{prime } , barely exceeds ≈ 100 GeV as a result of complementary variations in production cross sections and decay branching fractions of the heavy, neutral Higgs bosons.

Constraining new physics with SModelS version 2

We present version 2 of SModelS, a program package for the fast reinterpretation of LHC searches for new physics on the basis of simplified model results. The major novelty of the SModelS v2 series is an extended topology description with a flexible number of particle attributes, such as spin, charge, decay width, etc. This enables, in particular, the treatment of a wide range of signatures with long-lived particles. Moreover, constraints from prompt and long-lived searches can be evaluated simultaneously in the same run. The current database includes results from searches for heavy stable charged particles, disappearing tracks, displaced jets and displaced leptons, in addition to a large number of prompt searches. The capabilities of the program are demonstrated by two physics applications: constraints on long-lived charged scalars in the scotogenic model, and constraints on the electroweak-ino sector in the Minimal Supersymmetric Standard Model.

Nuclear 0ν2β decays in B-L symmetric SUSY model and in TeV scale left–right symmetric model

In this paper, we take the B-L supersymmetric standard model (B-LSSM) and TeV scale left–right symmetric model (LRSM) as two representations of the two kinds of new physics models to study the nuclear neutrinoless double beta decays (0ν2β) so as to see the senses onto these two kinds of models when the decays are taken into account additionally. Within the parameter spaces allowed by all the existing experimental data, the decay half-life of the nucleus 76Ge and 136Xe, (76Ge, 136Xe), is precisely calculated and the results are presented properly. Based on the numerical results, we conclude that there is greater room for LRSM type models than for B-LSSM type models in foreseeable future experimental observations on the decays.

The Higgs boson mass as fundamental parameter of the minimal supersymmetric standard model

In the Minimal Supersymmetric Standard Model (MSSM) the mass of the lightest neutral Higgs boson is determined by the supersymmetric parameters. In the m_hMSSM the precisely measured Higgs boson replaces the trilinear coupling A_t as input parameter. Expressions are derived to extract A_t in a semi-analytical form as a function of the light Higgs boson (pole) mass. An algorithm is developed and implemented at two-loop precision, generalizable to higher orders, to perform this inversion consistently. The result of the algorithm, implemented in the SuSpect spectrum calculator, is illustrated on a parameter set compatible with LHC measurements.

Discovery and Exclusion Prospects for Staus Produced by Heavy Higgs Boson Decays at the LHC

In a previous work, we developed a search strategy for staus produced by the decay of the heavy CP-even Higgs bosonHwithin the context of the largetanβregime of the minimal supersymmetric standard model (MSSM) in a scenario of large stau mixing. Here, we study the performance of such search strategy by confronting it with the complementary mixing pattern in which decays of both the CP-even and CP-odd heavy Higgs bosons contribute to the production ofτ~1τ~2∗+c.cpairs. Again, we focus on final states with two opposite-sign tau leptons and large missing transverse energy. We find that our proposed search strategy, although optimized for the large stau mixing scenario, is still quite sensitive to the complementary mixing pattern. We also extend the results reported in the preceding work for the large mixing scenario by including now the exclusion limits at the next run of the LHC and the prospects both for exclusion and discovery in a potential high-luminosity phase. Finally, we discuss the possibility to distinguish the two mixing scenarios when they share the same relevant mass spectrum and both reach the discovery level with our search strategy.

Flavor anomalies in supersymmetric scenarios with nonminimal flavor violation

Motivated by tensions between experimental measurements and SM predictions in $b\ensuremath{\rightarrow}s{\ensuremath{\ell}}^{+}{\ensuremath{\ell}}^{\ensuremath{-}}$ transitions, we present the first study of nonminimal flavor-violating minimal supersymmetric Standard Model (MSSM) scenarios contributing to the relevant Wilson coefficients to address the observed anomalies using SuperIso and MARTY. We calculate the full one-loop analytical contributions of the general MSSM to Wilson coefficients relevant for flavor anomalies, together with the anomalous muon magnetic dipole moment $(g\ensuremath{-}2{)}_{\ensuremath{\mu}}$. We show that, after imposing theoretical constraints on the flavor-violating parameters, we can find scenarios in agreement with the experimental measurements that can address at the same time the tensions in flavor observables and in $(g\ensuremath{-}2{)}_{\ensuremath{\mu}}$.

Muon anomalous magnetic dipole moment in the μ νSSM * *Supported by the National Natural Science Foundation of China (11705045, 11535002, 12075074), the Natural Science Foundation for Distinguished Young Scholars of Hebei Province (A2022201017), the Natural Science Foundation of Guangxi Autonomous Region (2022GXNSFDA035068), the youth top-notch talent support program of the Hebei Province, and Midwest Universities Comprehensive Strength Promotion project

Recently, the Muon g-2 experiment at Fermilab measured the muon anomalous magnetic dipole moment (MDM), , and reported that the new experimental average increases the difference between the experiment and the standard model (SM) prediction to 4.2σ. In this work, we reanalyze the muon anomalous MDM at the two-loop level in the μ from the ν Supersymmetric Standard Model ( SSM) combined with the updated experimental average. The SSM can explain the current difference between the experimental measurement and the SM theoretical prediction for the muon anomalous MDM, constrained by the 125 GeV Higgs boson mass and decays, the rare decay , and so on. We also investigate the anomalous MDM of the electron and tau lepton, and , at the two-loop level in the SSM. In addition, the decaying of the 125 GeV Higgs boson into a pair of charged leptons in the SSM is analyzed.

Restrictions on Parameters of Minimal Supersymmetric Standard Model

The Higgs boson with mass mh = 126 GeV was discovered at the Large Hadron Collider in 2012. Its mass corresponds both to the Standard Model of elementary-particles physics and to the mass of the most lightweight Higgs boson in the minimal supersymmetric standard model (MSSM). In this paper, we consider MSSM that does not preserve the CP-invariance and contains a large amount of parameters to be varied. Using the experimental value of the Higgs boson mass, we obtain restrictions on the parameters of the model, determine phenomenological scenarios, and analyze possible areas of the space of parameters.