Higgs Mass Research Articles

A minimal supersymmetric SU(5) missing-partner model

We explore a missing-partner model based on the minimal SU(5) gauge group with mathbf{75} , mathbf{50} and overline{mathbf{50 }} Higgs representations, assuming a super-GUT CMSSM scenario in which soft supersymmetry-breaking parameters are universal at some high scale M_{mathrm{in}} above the GUT scale M_{mathrm{GUT}}. We identify regions of parameter space that are consistent with the cosmological dark matter density, the measured Higgs mass and the experimental lower limit on tau (p rightarrow K^+ nu ). These constraints can be satisfied simultaneously along stop coannihilation strips in the super-GUT CMSSM with tan beta sim 3.5–5 where the input gaugino mass m_{1/2} sim 15–25 TeV, corresponding after strong renormalization by the large GUT Higgs representations between M_{mathrm{in}} and M_{mathrm{GUT}} to m_{mathrm{LSP}}, m_{{tilde{t}}_1} sim 2.5–5 TeV and m_{{tilde{g}}} sim 13–20 TeV, with the light-flavor squarks significantly heavier. We find that tau (p rightarrow K^+ nu ) lesssim 3 times 10^{34} years throughout the allowed range of parameter space, within the range of the next generation of searches with the JUNO, DUNE and Hyper-Kamiokande experiments.

Higgs flavor phenomenology in a supersymmetric left-right model with parity

In this paper, we focus on the supersymmetric model with left-right (LR) symmetry, that is especially proposed in our previous work [1]. In this model, there are four Higgs doublets in order to realize the Standard Model (SM) fermion masses and the Cabibbo-Kobayashi-Maskawa matrix. The heavy Higgs doublets unavoidably have flavor changing couplings to the SM fermions and induce flavor-changing neutral currents at tree level. We study broader parameter space than the previous work with including the renormalization group corrections to the Yukawa couplings between the LR breaking scale, mathcal{O} (1013) GeV, and the supersymmetry breaking scales, mathcal{O} (100) TeV. The CP violating observable in K– overline{K} mixing, ϵK, strongly constrains the model, so that heavy Higgs mass should be heavier than mathcal{O} (100) TeV. We study the lepton flavor violating (LFV) processes setting heavy Higgs masses to be 170 TeV. The branching ratios of μ → 3e and the μ–e conversion can be larger than 10−16 that could be covered by the future experiments. We also study the degree of fine-tuning in the parameter region that predicts testable LFV processes.

Probing loop effects in wrong-sign Yukawa coupling region of Type-II 2HDM

In the framework of 2HDM, we explore the wrong-sign Yukawa region with direct and indirect searches up to one-loop level. The direct searches include the latest H/A rightarrow f{bar{f}}, VV, Vh, hh reports at current LHC, and the study of indirect Higgs precision measurements works with current LHC, future HL-LHC and CEPC. At tree level of Type-II 2HDM, for degenerate heavy Higgs mass m_A=m_H=m_{H^pm }<800 GeV, the wrong-sign Yukawa regions are excluded largely except for the tiny allowed region around cos (beta -alpha )in (0.2,0.3) under the combined Higgs constraints. The excluded region is also nearly independent of parameter m_{12} or lambda v^2=m_A^2-m_{12}^2/(sin beta cos beta ). The situation changes a lot after including loop corrections to the indirect searches, for example m_A=1500 text {~GeV}, the region with lambda v^2<0 will be stronger constrained to be totally excluded. Whilst parameter space with lambda v^2>0 would get larger survived wrong-sign region for m_A=800 ~text {~GeV} compared to it at tree level. We also conclude Higgs direct searches works better on constraining lambda v^2 approx 0 GeV range than theoretical constraints. We also find that the loop-level wrong-sign Yukawa limit only occurs at mass decoupling scale.

Convergent Bayesian global fits of 4D composite Higgs models

Models in which the Higgs boson is a composite pseudo-Nambu-Goldstone boson offer attractive solutions to the Higgs mass naturalness problem. We consider three such models based on the minimal SO(5) → SO(4) symmetry breaking pattern, and perform convergent global fits on the models under a Bayesian framework in order to find the regions of their parameter spaces that best fit a wide range of constraints, including recent Higgs measurements. We use a novel technique to analyse the fine-tuning of the models, quantifying the tuning as the Kullback-Leibler divergence from the prior to the posterior probability on the parameter space. Each model is found to be able to satisfy all constraints at the 3σ level simultaneously. As a by-product of the fits, we analyse the collider phenomenology of our models in these viable regions. In two of the three models, we find that the gg → H → γγ cross section is less than ∼90% that predicted by the SM, which is already in slight tension with experiment and could potentially be ruled out in the future high-luminosity run of the LHC. In addition, the lightest fermions F arising from the new strong dynamics in these models are seen in general to lie above ∼1.1 TeV, with the F → tW+ and F → overline{b}{W}^{+} decays offering particularly promising channels for probing these models in future collider searches.

Search for the dark photon in B0 \u2192 A\u2032A\u2032, A\u2032 \u2192 e+e\u2212, \u03bc+\u03bc\u2212, and \u03c0+\u03c0\u2212 decays at Belle

We present a search for the dark photon A′ in the B0 → A′A′ decays, where A′ subsequently decays to e+e−, μ+μ−, and π+π−. The search is performed by analyzing 772 × 106 Boverline{B} events collected by the Belle detector at the KEKB e+e− energy-asymmetric collider at the ϒ(4S) resonance. No signal is found in the dark photon mass range 0.01 GeV/c2 ≤ mA′ ≤ 2.62 GeV/c2, and we set upper limits of the branching fraction of B0 → A′A′ at the 90% confidence level. The products of branching fractions, mathrm{mathcal{B}}left({B}^0to A^{prime }A^{prime}right)times mathrm{mathcal{B}}{left(Aprime to {e}^{+}{e}^{-}right)}^2 and mathrm{mathcal{B}}left({B}^0to A^{prime }A^{prime}right)times mathrm{mathcal{B}}{left(Aprime to {mu}^{+}{mu}^{-}right)}^2 , have limits of the order of 10−8 depending on the A′ mass. Furthermore, considering A′ decay rate to each pair of charged particles, the upper limits of mathrm{mathcal{B}}left({B}^0to A^{prime }A^{prime}right) are of the order of 10−8–10−5. From the upper limits of mathrm{mathcal{B}}left({B}^0to A^{prime }A^{prime}right) , we obtain the Higgs portal coupling for each assumed dark photon and dark Higgs mass. The Higgs portal couplings are of the order of 10−2–10−1 at {m}_{hprime}simeq {m}_{B^0} ± 40 MeV/c2 and 10−1–1 at {m}_{hprime}simeq {m}_{B^0} ± 3 GeV/c2.

Dimensional transmutation in gravity and cosmology

We review (and extend) the analysis of general theories of all interactions (gravity included) where the mass scales are due to dimensional transmutation. Quantum consistency requires the presence of terms in the action with four derivatives of the metric. It is shown, nevertheless, how unitary is achieved and the classical Ostrogradsky instabilities can be avoided. The four-derivative terms also allow us to have a UV complete framework and a naturally small ratio between the Higgs mass and the Planck scale. Moreover, black holes of Einstein gravity with horizons smaller than a certain (microscopic) scale are replaced by horizonless ultracompact objects that are free from any singularity and have interesting phenomenological applications. We also discuss the predictions that can be compared with observations of the microwave background radiation anisotropies and find that this scenario is viable and can be tested with future data. Finally, how strong phase transitions can emerge in models of this type with approximate scale symmetry and how to test them with GW detectors is reviewed and explained.

Emergent 2HDM in the Low-Skiba-Smith little Higgs model: Musings from flavor and electroweak physics

The low energy effective theory ($\sim$ TeV) of the little-Higgs model with $SU(6)/Sp(6)$, as proposed by Low, Skiba and Smith (LSS), exhibits a two-Higgs doublet model (2HDM) structure. The symmetry dictates interesting Yukawa patterns, translating to non-trivial fermion couplings with both of the Higgs doublets. The couplings of the scalars with the fermions can induce flavor changing neutral currents (FCNC), which get constraints from flavor physics observables such as BR$(B\rightarrow X_s\gamma)$, $B_s - \bar{B}_s$ mixing etc. The precision measurement of $Z b \bar{b}$ vertex, the top and Higgs mass along with other Higgs coupling measurements at the Large Hadron Collider (LHC) also enforce severe restrictions on the LSS model. Direct LHC search results of beyond the Standard Model (BSM) particles also impose bounds on the masses. We probe the LSS model in view of the above constraints through a random scan in the multi-dimensional parameter space. We observe, on contrary to the general 2HDM scenario, the emergent 2HDM from the LSS model is less constrained from the flavor data and the $Z b \bar{b}$ measurement but is severely constrained form the electroweak (EW) searches at the LHC. From the flavor data and $Z b \bar{b}$, we find that the charged Higgs mass is relaxed with $\tan\beta$ being restricted to $0.5-5$, whereas the charged Higgs mass is pushed to larger than 1 TeV along with $\tan\beta$ being further restricted to $< 3$ when the LHC bounds are incorporated.

MSSM at future Higgs factories * *HL was Supported by the National Natural Science Foundation of China (NNSFC) (11635009) and Natural Science Foundation of Shandong Province (ZR2017JL006). HS and SS are Supported in part by the Department of Energy (DE-FG02-13ER41976/DE-SC0009913). WS is Supported by the Australian Research Council (ARC) Centre of Excellence for Dark Matter Particle Physics (CE200100008). JMY was

In this work, we study the implications of Higgs precision measurements at future Higgs factories for the MSSM parameter space, focusing on the dominant stop sector contributions. We perform a multi-variable fit to both the signal strength for various Higgs decay channels at Higgs factories and the Higgs mass. The χ 2 fit results show sensitivity to mA , tan β, stop mass parameter m SUSY , and the stop left-right mixing parameter Xt. We also study the impact of the Higgs mass prediction on the MSSM and compare the sensitivities of different Higgs factories.

Crunching Dilaton, Hidden Naturalness.

We introduce a new approach to the Higgs naturalness problem. The Higgs mixes with the dilaton of a conformal field theory (CFT) sector whose true ground state has a large negative vacuum energy. If the Higgs vacuum expectation value is nonzero and below O(TeV), the CFT admits a second metastable vacuum, where the expansion history of the Universe is conventional. As a result, only Hubble patches with unnaturally small values of the Higgs mass do not immediately crunch. The main experimental prediction of this mechanism is a dilaton in the 0.1-10GeV range that mixes with the Higgs and can be detected at future colliders and experiments searching for weakly coupled particles.

Two-loop matching of renormalizable operators: general considerations and applications

Low-energy effective field theories (EFT) encode information about the physics at high energies — i.e., the high-energy theory (HET). To extract this information the EFT and the HET have to be matched to each other. At the one-loop level, general results for the matching of renormalizable operators have already been obtained in the literature. In the present paper, we take a step towards a better understanding of renormalizable operator matching at the two-loop level: focusing on the diagrammatic method, we discuss in detail the various contributions to two-loop matching conditions and compare different approaches to derive them. Moreover, we discuss which observables are best suited for the derivation of matching conditions. As a concrete application, we calculate the mathcal{O}left({alpha}_t{alpha}_sright) and mathcal{O}left({alpha}_t^2right) matching conditions of the scalar four-point couplings between the Standard Model (SM) and the Two-Higgs-Doublet Model (THDM) as well as the THDM and the Minimal Supersymmetric Standard Model (MSSM). We use the derived formulas to improve the prediction of the SM-like Higgs mass in the MSSM using the THDM as EFT.

Landscape Higgs boson and sparticle mass predictions from a logarithmic soft term distribution

Recent work on calculating string theory landscape statistical predictions for the Higgs and sparticle mass spectrum from an assumed power-law soft term distribution yields an expectation for m(h)~ 125 GeV with sparticles (save light higgsinos) somewhat beyond reach of high-luminosity LHC. A recent examination of statistics of SUSY breaking in IIB string models with stabilized moduli suggests a power-law for models based on KKLT stabilization and uplifting while models based on large-volume scenario (LVS) instead yield an expected logarithmic soft term distribution. We evaluate statistical distributions for Higgs and sparticle masses from the landscape with a log soft term distribution and find the Higgs mass still peaks around ~125 GeV with sparticles beyond LHC reach, albeit with somewhat softer distributions than those arising from a power-law.

Standard model meets gravity: Electroweak symmetry breaking and inflation

We propose a model for combining the Standard Model (SM) with gravity. It relies on a non-minimal coupling of the Higgs field to the Ricci scalar and on the Palatini formulation of gravity. Without introducing any new degrees of freedom in addition to those of the SM and the graviton, this scenario achieves two goals. First, it generates the electroweak symmetry breaking by a non-perturbative gravitational effect. In this way, it does not only address the hierarchy problem but opens up the possibility to calculate the Higgs mass. Second, the model incorporates inflation at energies below the onset of strong-coupling of the theory. Provided that corrections due to new physics above the scale of inflation are not unnaturally large, we can relate inflationary parameters to data from collider experiments.

Variational technique for gauge boson masses

In this work, a novel mechanism for spontaneous symmetry breaking is presented. This mechanism avoids quadratic divergencies and is thus capable of addressing the hierarchy problem in gauge theories. Using the scale-dependent effective action $\Gamma_{k}$ minimally coupled to a gravitational sector, variational parameter setting is applied. This provides a mass and vacuum expectation value as a function of the constants arising in the low scale expansion of Newtons' and cosmological couplings. A comparison with experimental data, such as the Higgs mass, allows putting restrictions on these constants. With this generic approach one can compare with explicit candidates for an effective field theory of gravity. As an example, we use the asymptotic safety scenario, where we find restrictions on the matter content of the theory.

Higgsino asymmetry and direct-detection constraints of light dark matter in the NMSSM with non-universal Higgs masses * *Supported by the National Natural Science Foundation of China (11605123)

In this study, we analyze the direct-detection constraints of light dark matter in the next-to minimal supersymmetric standard model (NMSSM) with non-universal Higgs masses (NUHM); we specially focus on the correlation between higgsino asymmetry and spin-dependent (SD) cross section. We draw the following conclusions. (i) The SD cross section is proportional to the square of higgsino asymmetry in dark matter in the NMSSM-NUHM, and hence, it is small for highly singlino-dominated dark matter. (ii) The higgsino-mass parameter is smaller than approximately in the NMSSM-NUHM due to the current muon g-2 constraint, but our scenario with light dark matter can still be alive under current constraints including the direct detection of dark matter in the spin-dependent channel. (iii) With a sizeable higgsino component in the light dark matter, the higgsino asymmetry and SD cross section can also be sizeable, but dark matter relic density is always small; thus, it can escape the direct detections. (iv) Light dark matter in the - and Z-funnel annihilation channels with sufficient relic density can be covered by future LUX-ZEPLIN (LZ) 7-ton in SD detections. (v) The spin-independent (SI) cross section is dominated by - and -exchanging channels, which can even cancel each other in some samples, leaving an SI cross section smaller by a few orders of magnitude than that of one individual channel.

Low-energy probes of no-scale SU(5) super-GUTs

We explore the possible values of the mu rightarrow e gamma branching ratio, text {BR}(mu rightarrow egamma ), and the electron dipole moment (eEDM), d_e, in no-scale SU(5) super-GUT models with the boundary conditions that soft supersymmetry-breaking matter scalar masses vanish at some high input scale, M_mathrm{in}, above the GUT scale, M_{mathrm{GUT}}. We take into account the constraints from the cosmological cold dark matter density, Omega _{CDM} h^2, the Higgs mass, M_h, and the experimental lower limit on the lifetime for p rightarrow K^+ bar{nu }, the dominant proton decay mode in these super-GUT models. Reconciling this limit with Omega _{CDM} h^2 and M_h requires the Higgs field responsible for the charge-2/3 quark masses to be twisted, and possibly also that responsible for the charge-1/3 and charged-lepton masses, with model-dependent soft supersymmetry-breaking masses. We consider six possible models for the super-GUT initial conditions, and two possible choices for quark flavor mixing, contrasting their predictions for proton decay with versions of the models in which mixing effects are neglected. We find that tau left( prightarrow K^+ bar{nu }right) may be accessible to the upcoming Hyper-Kamiokande experiment, whereas all the models predict text {BR}(mu rightarrow egamma ) and d_e below the current and prospective future experimental sensitivities or both flavor choices, when the dark matter density, Higgs mass and current proton decay constraints are taken into account. However, there are limited regions with one of the flavor choices in two of the models where mu rightarrow e conversion on a heavy nucleus may be observable in the future. Our results indicate that there is no supersymmetric flavor problem in the class of no-scale models we consider.

HiggsSignals-2: probing new physics with precision Higgs measurements in the LHC 13 TeV era

The program HiggsSignals confronts the predictions of models with arbitrary Higgs sectors with the available Higgs signal rate and mass measurements, resulting in a likelihood estimate. A new version of the program, HiggsSignals-2, is presented that contains various improvements in its functionality and applicability. In particular, the new features comprise improvements in the theoretical input framework and the handling of possible complexities of beyond-the-SM Higgs sectors, as well as the incorporation of experimental results in the form of simplified template cross section (STXS) measurements. The new functionalities are explained, and a thorough discussion of the possible statistical interpretations of the HiggsSignals results is provided. The performance of HiggsSignals is illustrated for some example analyses. In this context the importance of public information on certain experimental details like efficiencies and uncertainty correlations is pointed out. HiggsSignals is continuously updated to the latest experimental results and can be obtained at https://gitlab.com/higgsbounds/higgssignals.

Non-thermal production of lepton asymmetry and dark matter in minimal seesaw with right handed neutrino induced Higgs potential

Within Type-I seesaw mechanism, Higgs mass can be dynamically generated via quantum effects of the right handed neutrinos assuming the potential is nearly conformal at the Ultra-Violet. The scenario, named as the "Neutrino Option" allows RH neutrino mass scale upto M ≲ 107 GeV to be consistent with light neutrino masses, mixing and Higgs mass. Therefore, it is not consistent with standard hierarchical thermal leptogenesis. Parameter space for thermal resonant leptogenesis is highly constrained in this model. We point out that non-thermal pair production of RH neutrinos from inflaton decay corresponds in general to a mild degree of resonance in the CP asymmetry parameter and allows RH mass scale to be smaller more than by an order of magnitude than the thermal strong resonance case. Within the similar parameter space of thermal leptogenesis, RH neutrinos can also be produced from inflaton decay along with a Dark Matter having mass MDM ≲ 320 MeV. The main constraint in the latter scenario comes from the Lyα constraints on Dark Matter free streaming. We show in addition, that the Neutrino Option introduces a 'phantom window' for the RH mass scale, in which contrary to the usual scenarios, CP asymmetry parameter for leptogenesis decreases with the increase of the RH mass scale and minimally fine-tuned seesaw models naturally exhibit this `phantom window'.

From Veltman’s Conditions to Finite Unification

First we review Veltman's suggestion to attack the naturalness problem in the Standard model by requiring absence of quadratic divergences and the resulting mass formula. Then we emphasise the influence of Veltman's suggestion in strengthening the belief that supersymmetry is the natural playground for solving the problem of quadratic divergences. Going further, we recall few sporadic suggestions concerning the cancellation of the logarithmic divergences too, which in the framework of supersymmetry has led to the construction of all-loop Finite Theories with the use of the idea of reduction of couplings. Eventually, we concentrate on a specific Finite Unified Theory and its successful predictions for the top and Higgs mass, among others, and the prospects of its final justification in future collider searches.

Power-aligned 2HDM: a correlative perspective on (g \u2212 2)e,\u03bc

With the hypothesis of minimal flavor violation, we find that there exists a power-aligned relation between the Yukawa couplings of the two scalar doublets in the two-Higgs-doublet model with Hermitian Yukawa matrices. Within such a power-aligned framework, it is found that a simultaneous explanation of the anomalies observed in the electron and muon anomalous magnetic moments can be reached with TeV-scale quasi-degenerate Higgs masses, and the resulting parameter space is also phenomenologically safer under the B-physics, Z and τ decay data, as well as the current LHC bounds. Furthermore, the flavor-universal power that enhances the charged-lepton Yukawa couplings prompts an interesting correlation between the two anomalies, which makes the model distinguishable from the (generalized) linearly aligned and the lepton-specific two-Higgs-doublet models that address the same anomalies but in a non-correlative manner, and hence testable by future precise measurements.

Higgs decay to light (pseudo)scalars in the semi-constrained NMSSM * *Supported by National Natural Science Foundation of China (NSFC) (11605123)

The next-to minimal supersymmetric standard model (NMSSM) with non-universal Higgs masses, i.e., the semi-constrained NMSSM (scNMSSM), extends the minimal supersymmetric standard model (MSSM) by a singlet superfield and assumes universal conditions, except for the Higgs sector. It can not only maintain the simplicity and grace of the fully constrained MSSM and NMSSM and relieve the tension they have been facing since the discovery of the 125-GeV Higgs boson but also allow for an exotic phenomenon wherein the Higgs decay into a pair of light ( ) singlet-dominated (pseudo)scalars (hereafter, in this paper, we use "scalar" for both scalars and pseudoscalars, considering pseudoscalars can also be called CP-odd scalars). This condition can be classified into three scenarios according to the identitiesof the SM-like Higgs and the light scalar: (i) the light scalar is CP-odd, and the SM-like Higgs is ; (ii) the light scalar is CP-odd, and the SM-like Higgs is ; and (iii) the light scalar is CP-even, and the SM-like Higgs is . In this work, we compare the three scenarios, checking the interesting parameter regions that lead to the scenarios, the mixing levels of the doublets and singlets, the tri-scalar coupling between the SM-like Higgs and a pair of light scalars, the branching ratio of Higgs decay to the light scalars, and sensitivities in the detection of the exotic decay at the HL-LHC and future lepton colliders such as CEPC, FCC-ee, and ILC. Finally, several interesting conclusions are drawn, which are useful for understanding the different delicate mechanisms of the exotic decay and designing colliders in future.