Any extension of the standard model that aims to describe TeV-scale physics without fine-tuning must have a radiatively-stable Higgs potential. In little Higgs theories, radiative stability is achieved through so-called collective symmetry breaking. In this letter, we focus on the necessary conditions for a little Higgs to have a collective Higgs quartic coupling. In one-Higgs doublet models, a collective quartic requires an electroweak triplet scalar. In two-Higgs doublet models, a collective quartic requires a triplet or singlet scalar. As a corollary of this study, we show that some little Higgs theories have dangerous singlets, a pathology where collective symmetry breaking does not suppress quadratically-divergent corrections to the Higgs mass.
We investigate Planck scale boundary conditions on Higgs quartic interactions and their $β$-functions in the SM augmented by an additional complex scalar. We use renormalisation group running at two-loops, and include both theoretical and experimental constraints. We find that the boundary condition $λ=β_λ=0$ at the Planck scale is compatible with the current Higgs and top mass measurements, but requires additional scalars lighter than about $600\,$GeV.
An extension of the Standard Model with a hidden sector which consists of gauge singlets (a Dirac fermion $χ$ and a scalar $S$) plus a vector boson $V_μ$ (dark massive photon) is studied. The singlet scalar interacts with the Standard Model sector through the triple and quartic scalar interactions, while the singlet fermion and vector boson field interact with the Standard Model only via the singlet scalar. The scalar field generates the vector boson's mass. Perspectives for future $e^{-}e^{+}$ colliders is considered.
We study the implications of the Higgs discovery and of recent results from dark matter searches on real singlet scalar dark matter. The phenomenology of the model is defined by only two parameters, the singlet scalar mass $m_S$ and the quartic coupling $a_2$ between the SU(2) Higgs and the singlet scalar. We concentrate on the window $5 < m_S/{\rm GeV} < 300$. The most dramatic impact on the viable parameter space of the model comes from direct dark matter searches with LUX, and, for very low masses in the few GeV range, from constraints from the invisible decay width of the Higgs. In the res…
In this article we examine the prospect of first order phase transition with a Y=0 real $SU(2)$ triplet extension of the Standard Model, which remains odd under $Z_2$, considering the observed Higgs boson mass, perturbative unitarity, dark matter constraints, etc. Especially we investigate the role of Higgs-triplet quartic coupling considering one- and two-loop beta functions and compare the results with the complex singlet extension case. It is observed that at the one-loop level, no solution can be found for both, demanding the Planck scale perturbativity. However, for a much lower scale of …
Revisiting Singlet Fermion Dark Matter with a Scalar Portal: Connecting Higgs Phenomenology and Strong Electroweak Phase Transition
Indian Institute of Technology Guwahati（印度理工学院古瓦哈提分校）；Gokhale Memorial Girls’ College（戈卡尔纪念女子学院）；University of Delhi（德里大学）；Central China Normal University（华中师范大学）
In this work, we investigate the possibility to realize inflation and strong first order electroweak phase transitions(SFOEWPT) together with the relic density explanation. We studied the usual Higgs-portal real singlet dark matter model and the global U(1) breaking complex singlet model with the pseudoscalar being dark matter candidate. We focus on higher dark matter parameter regions due to the lower dark matter masses region are almost excluded by the current direct detection experiments except that of the so-called ${\it Higgs~ funnel ~regime}$ with $m_{DM}\sim m_h/2$. In both models, the …
One of the simplest extensions of the Standard Model (SM) comprises the inclusion of a massive real scalar field, neutral under the SM gauge groups, to be a dark matter candidate. The addition of a dimension-six term into the potential of the scalar dark matter enables the appearance of a false vacuum that describes the cosmic acceleration. We show that the running of the singlet self-interaction and the Higgs portal coupling differs from the standard scalar singlet dark matter model. If we maintain a positive quartic coupling, it is also possible to describe the accelerated expansion of the U…
This work explores the possibility of obtaining a mass gap in Yang-Mills theories via the intrinsic gauge bosons, without invoking a separate Higgs boson or fermion-antifermion pairs. Instead, pairs of gauge bosons in the spin and isospin singlet state form a pair of composite Higgs bosons which can be viewed as the simplest possible glueball of Yang-Mills gauge theories. Quadratic and quartic gauge boson self-interactions form a potential that leads to a finite expectation value of the gauge boson amplitude. Transverse polarization ensures Lorentz invariance of the vacuum after averaging over…
We investigate the electroweak vacuum stability in an extended version of the Standard Model which incorporates two additional singlet scalar fields and three right handed neutrinos. One of these extra scalars plays the role of dark matter while the other scalar not only helps in making the electroweak vacuum stable but also opens up the low mass window of the scalar singlet dark matter (< 500 GeV). We consider the effect of large neutrino Yukawa coupling on the running of Higgs quartic coupling. We have analyzed the constraints on the model and identify the range of parameter space which is c…
We investigate the production of three Higgs bosons at a proton-proton collider running at a centre-of-mass energy of 100 TeV, all of which decay into $b$-jets. This final state encapsulates by far the largest fraction of the total cross section of triple Higgs boson production, approximately $20\%$. We examine, by constructing detailed phenomenological analyses, two scenarios: (i) one in which the triple and quartic Higgs boson self-couplings are modified independently by new phenomena with respect to their Standard Model (SM) values and (ii) an extension of the SM by a gauge-singlet scalar t…
The most general renormalizable interaction between the Higgs sector and a new gauge-singlet scalar $S$ is governed by two interaction terms: cubic and quartic. The quartic interaction is only loosely constrained by invisible Higgs decays. Given current experimental limits about $10\%$ of all Higgs bosons created at the LHC can be converted to new scalars with the mass up to $m_{\rm Higgs}/2$. This can significantly extend the reach of the LHC-based Intensity Frontier experiments. We analyze the sensitivity of the FASER experiment to this model and discuss modest changes in the FASER 2 design …
Vacuum stability in the Standard Model is problematic as the Higgs quartic self-coupling runs negative at a renormalization scale of about $10^{10}$ GeV. We consider a non-supersymmetric SO(10) grand unification model for which gauge coupling unification is made possible through an intermediate scale gauge group, $G_{\text{int}}=\text{SU}(3)_C\otimes \text{SU}(2)_L\otimes \text{SU}(2)_R \otimes \text{U}(1)_{B-L}$. $G_{\text{int}}$ is broken by the vacuum expectation value of a 126 of SO(10) which not only provides for neutrino masses through the seesaw mechanism but also preserves a discrete $…
We propose that the TeV scale mirage mediation in the Next-to-Minimal Supersymmetric Standard Model (NMSSM) is a novel solution for the little hierarchy problem in supersymmetry. The 125 GeV Higgs boson can be accommodated with the new quartic coupling or the mixing with the singlet. The fine-tuning measures are estimated numerically and found as low as 10\% or below for $1.5$ TeV gluino and $1$ TeV stop. The higgsino can be as heavy as 500 GeV without deteriorating the fine-tuning. An undesirable singlet-doublet mixing in the Higgs sector is suppressed due to approximate scale symmetries. We …
It has been observed that an automatic alignment without decoupling is predicted at tree-level in a Two-Higgs Doublet Model (2HDM) with extended supersymmetry in the gauge and Higgs sectors. Moreover, it was found that radiative corrections preserve this alignment to a very good precision. We show that it is the non-abelian global $SU(2)_R$ R-symmetry that is at the origin of this alignment. This differs from previously considered Higgs family symmetries as it is present only in the quartic part of the Higgs potential. It can not be imposed to the quadratic part which has to be generated by $N…
"Super"-Dilatation Symmetry of the Top-Higgs System
顶-希格斯系统，由顶夸克（LH二重态，RH单线态）和希格斯玻色子动力学项组成，规范场设置为零，具有精确（模总发散）对称性，费米子和希格斯场都以超对称的方式移动和混合。完整的Higgs-Yukawa相互作用和Higgs势，包括额外的1/Λ^2 N JL类相互作用，也具有这种对称性到0（1/Λ^4）直到零算符。因此，相互作用拉格朗日量可以看作是1/^2的幂级数。这种对称性涉及到希格斯四次相互作用与希格斯-汤川相互作用的相互作用，并暗示了在高能尺度Λ=几TeV时，顶-汤川耦合g与希格斯四次耦合λ之间的关系λ= \half g ^2。我们认为这是一种新的物理尺度。顶夸克在对称相中是无质量的，满足南武-戈德斯通定理。由于λ和g的相互作用，电流的费米子位移部分为\propto（1-H^ \dagger H/v ^2），在破缺相中消失。因此，在破缺相中，南武-戈德斯通定理被简单地回避了，顶夸克变重了（它不是戈德斯通）。我们有m_t=m_h，经过辐射修正，原则上可以使希格斯粒子与实验一致。
We investigate asymptotic safety of a toy model of a singlet-scalar extension of the Higgs sector including two real scalar fields under the impact of quantum-gravity fluctuations. Employing functional renormalization group techniques, we search for fixed points of the system which provide a tentative ultraviolet completion of the system. We find that in a particular regime of the gravitational parameter space the canonically marginal and relevant couplings in the scalar sector -- including the mass parameters -- become irrelevant at the ultraviolet fixed point. The infrared potential for the …
In this letter we study the Higgs mass in the NMSSM with supersymmetry breaking at high scales $M_{SS}$. With the Standard Model as the effective low energy theory, the computation of the Higgs mass relies on the matching condition of the quartic coupling $λ$ at $M_{SS}$. In the MSSM, the latter is fixed to a semi-positive value and, thus, sets an upper bound on the SUSY-breaking scale near $M_{SS}\simeq 10^{10}\text{GeV}$. In the NMSSM, $λ(M_{SS})$ receives an additional contribution induced by the singlet which allows for negative values of $λ(M_{SS})$. In turn, for the measured value of the…
We propose a simple non-supersymmetric grand unified theory (GUT) based on the gauge group $SO(10) \times U(1)_ψ$. The model includes 3 generations of fermions in ${\bf 16}$ ($+1$), ${\bf 10}$ ($-2$) and ${\bf 1}$ ($+4$) representations. The ${\bf 16}$-plets contain Standard Model (SM) fermions plus right-handed neutrinos, and the ${\bf 10}$-plet and the singlet fermions are introduced to make the model anomaly-free. Gauge coupling unification at $M_{GUT} \simeq 5 \times 10^{15}-10^{16}$ GeV is achieved by including an intermediate Pati-Salam breaking at $M_{I} \simeq 10^{12}-10^{11}$ GeV, whi…
