We present general expressions for the oblique parameters S, T, U, V, W, and X in the SU(2)xU(1) electroweak model with an arbitrary number of scalar SU(2) doublets, with hypercharge 1/2, and an arbitrary number of scalar SU(2) singlets.
We study, from theoretical and phenomenological angles, the Higgs boson oblique parameter $\hat{H}$, as the hallmark of off-shell Higgs physics. $\hat{H}$ is defined as the Wilson coefficient of the sole dimension-6 operator that modifies the Higgs boson propagator, within a Universal EFT. Theoretically, we describe self-consistency conditions on Wilson coefficients, derived from the Källén-Lehmann representation. Phenomenologically, we demonstrate that the process $gg\to h^\ast \to VV$ is insensitive to propagator corrections from $\hat{H}$, and instead advertise four-top production as an eff…
The oblique S parameter in higgsless electroweak models
本文提出了一种单圈计算弱对称破缺的无希格斯玻色子模型中的斜S参数的方法。我们使用了一个最多有两个导数的广义有效拉格朗日量,实现了具有Goldstones、规范玻色子和一个矢量多重态和轴矢量共振多重态的手征对称性破缺SU(2)_L x SU(2)_R -> SU(2)_{L+R}。估计是基于短距离的限制和分散的方法提出的Peskin和Takeuchi。
In view of the recent high precision measurement of the Standard Model $W$ boson mass at the CDF II detector, we compute the contributions to the oblique parameters $S$, $T$ and $U$ coming from the two additional Higgs doublets (one inert and one hidden) as well as the hidden neutral dark gauge bosons and extra heavy fermions in the gauged two-Higgs-doublet model (G2HDM). While the effects from the hidden Higgs doublet and new heavy fermions are found to be minuscule, the hidden gauge sector $SU(2)_H \times U(1)_X$ with gauge coupling strength $\gtrsim 10^{-2}$ and gauge boson mass $\gtrsim 10…
We present general formulas for the oblique-correction parameters $S$, $T$, $U$, $V$, $W$, and $X$ in an extension of the Standard Model having arbitrary numbers of singlet, doublet, and triplet quarks with electric charges $-4/3$, $-1/3$, $2/3$, and $5/3$ that mix with the standard quarks of the same charge.
b quark Electric Dipole moment in the general two Higgs Doublet and three Higgs Doublet models
本文研究了在Higgs扇区中具有O(2)对称性的一般双Higgs偶线模型(模型III)和三Higgs偶线模型中b夸克的电偶极距。我们分析了这个量的依赖性,新的阶段来自复杂的汤川耦合和质量的带电和中性希格斯玻色子玻色子。我们看到b夸克的电偶极矩在10^{-20} e cm的数量级,这是一个非常大的值相比,在SM和两个Higgs Doublet模型(模型II)与真正的汤川耦合。
In this talk, we report unitarity constraints and phenomenological studies at the Large Hadron Collider for the extra Higgs bosons of a Composite 2-Higgs Doublet Model.
We calculate the two-loop contributions from a modified trilinear Higgs self-interaction, $κ_λλ_{\rm SM} v h^3$, to the electroweak oblique parameters $S$ and $T$. Using the current bounds on $S$ and $T$ from electroweak measurements, we find the 95% C.L. constraint on the modified trilinear coupling to be $-14.0 \leq κ_λ\leq 17.4$. The largest effects on $S$ and $T$ arise from two insertions of the modified trilinear coupling that result in $T/ S \simeq -3/2$; remarkably, this is nearly parallel to the axis of the tightest experimental constraint in the $S$-$T$ plane. No contributions to $S$ …
We derive the complete set of continuous maximal symmetries for Standard Model (SM) alignment that may occur in the tree-level scalar potential of multi-Higgs Doublet Models, with $n > 2$ Higgs doublets. Our results generalize the symmetries of SM alignment, without decoupling of large mass scales or fine-tuning, previously obtained in the context of two-Higgs Doublet Models.
We investigate the new contributions to the parameters $g_L$ and $g_R$ of the $Z b \bar b$ vertex in a multi-Higgs-doublet model (MHDM). We emphasize that those contributions generally worsen the fit of those parameters to the experimental data. We propose a solution to this problem, wherein $g_R$ has the opposite sign from the one predicted by the Standard Model; this solution, though, necessitates light scalars and large Yukawa couplings in the MHDM.
In this paper, we propose a scheme for neutrino mass generation. A Higgs singlet is introduced in the Standard Model of particle physics (SM). All of this new singlet and the charged and neutral Higgs fields in the original Higgs doublet are assumed to have nonzero vacuum expectation values (VEVs). The normal hierarchy of neutrino masses is evidently preferred in our scheme. The neutrino masses are explicitly calculated.
With no conclusive signal till date of the minimal supersymmetric and extra dimensional models at the Large Hadron Collider (LHC), the issue of fine-tuning of the Higgs mass still calls for some attention. It could be very possible that the observed Higgs boson of mass 125 GeV has its origin in a non-supersymmetric extended scalar sector, and, it still has properties strikingly similar to the Standard Model Higgs. In such cases, however, one relies upon possible cancellations in the quadratic divergence of the Higgs mass to uphold naturalness. In this work, we have investigated this possibilit…