We study the possibility of constructing the NMSSM from the heterotic string. String derived NMSSMs are much more rare than MSSMs due to the extra requirement that there exist a light singlet which couples to the Higgs pairs. They share the common feature that the singlet self-interactions are typically suppressed, leading to either the "decoupling" or the Peccei-Quinn limit of the NMSSM. In the latter case, the spectrum contains a light pseudoscalar which may be relevant to the MSSM fine-tuning problem. We provide a Z_6 heterotic orbifold example of the NMSSM with approximate Peccei-Quinn symmetry, whose origin lies in the string selection rules combined with our choice of the vacuum configuration.
鉴于最近发现的125 GeV的希格斯玻色子，我们研究了次极小超对称标准模型（NMSSM）的Peccei-Quinn不变扩展的现象学。极小模型没有NMSSM单重场的二次和三次项，预言了一个轻的类单重最轻超对称粒子（LSP）。该模型受到希格斯粒子不可见衰变和LSP的暗物质特性的强烈约束，而一些约束可以通过假设Peccei-Quinn扇区中轴子的CP偶伴saxion导致后期熵产生稀释热LSP密度来放松。该模型的对撞机信号包含多喷流和$h/W/Z$加上丢失能量，在14 TeV LHC运行的早期就能发现。
We investigate a particular version of the Peccei-Quinn (PQ) NMSSM characterized by an economical and rigidly hierarchical flavor structure and based on flavored gauge mediation and on some considerations inspired by string theory GUTs. In this way we can express the Lagrangian of the PQ NMSSM through very few parameters. The obtained model is studied numerically and confronted with the most relevant phenomenological constraints. We show that typical spectra are for the most part too heavy to be significantly probed at the LHC, but regions of the parameter space exist yielding signatures that …
The next-to-minimal supersymmetric standard model can host light neutralino dark matter with mass of order GeV scale. It is dominated by the singlino component as a result of approximate Peccei-Quinn symmetry. This paper is devoted to address the question how light such neutralino dark matter can be in the light of the LHC Run 1 data as well as the latest LUX and Xenon1T limits. In particular, we show the sensitivity of parameter space of dark matter mass with respect to $Z$ boson and SM Higgs invisible decay.
Light Dark Matter and the Electroweak Phase Transition in the NMSSM
我们分析了真空和电弱相变的NMSSM接近Peccei-Quinn对称极限的稳定性。这个极限包含质量明显小于弱标度的轻暗物质（DM）粒子，以及轻CP偶和CP奇希格斯玻色子玻色子。这样的轻粒子导致一致的遗迹密度，并促进大的自旋独立的直接DM检测截面，这可能会适应最近报道的签名在DAMA和CoGeNT实验。研究有限温度下的单圈有效势，我们发现当最轻的CP偶Higgs质量为几GeV量级时，电弱相变趋向于一级强相变.直接检测截面和最轻的CP-偶希格斯质量之间的反比关系意味着10 $^{-41}$ cm $^2$量级的截面与强的一阶相变相关。
We consider the scenario in which the Peccei-Quinn symmetry breaking is followed by a period of inflation. A particularly interesting case is that the string-domain wall network produced by the symmetry breaking enters the horizon after the QCD phase transition. We show that the abundance of axions produced by such a string-domain wall network is counterintuitively much larger than the conventional post-inflationary Peccei-Quinn symmetry breaking scenario. As a result, a scenario with the axion decay constant even as low as the astrophysical bound of about $10^8$ GeV can explain the observed a…
I will show, via effective field theory (EFT) techniques, that obtaining an observationally consistent relic density while evading stringent direct detection limits and maintaining $h_{125}$ phenomenology in an extended Higgs sector can be easily achieved. I will then map such an EFT to the low energy limit of the NMSSM with the Higgsinos integrated out. Both the singlino and the singlet-like CP-odd and even scalars in the NMSSM may play a relevant role in such a scenario, while being difficult to probe via conventional searches. The singlet sector of the general NMSSM can be mapped on to a 2H…
A highly bino-like Dark Matter (DM), which is the Lightest Supersymmetric Particle (LSP), could be motivated by the stringent upper bounds on the DM direct detection rates. This is especially so when its mass is around or below 100 GeV for which such a bound tends to get most severe. Requiring not so large a higgsino mass parameter, that would render the scenario reasonably natural, prompts such a bino-like state to be relatively light. In the Minimal Supersymmetric Standard Model (MSSM), in the absence of comparably light scalars, such an excitation, if it has to be a thermal relic, is unable…
We study the formation and evolution of topological defects in an aligned axion model with multiple Peccei-Quinn scalars, where the QCD axion is realized by a certain combination of the axions with decay constants much smaller than the conventional Peccei-Quinn breaking scale. When the underlying U(1) symmetries are spontaneously broken, the aligned structure in the axion field space exhibits itself as a complicated string-wall network in the real space. We find that the string-wall network likely survives until the QCD phase transition if the number of the Peccei-Quinn scalars is greater than…
We study the axion strings with the electroweak gauge flux in the DFSZ axion model and show that these strings, called the electroweak axion strings, can exhibit superconductivity without fermionic zero modes. We construct three types of electroweak axion string solutions. Among them, the string with $W$-flux can be lightest in some parameter space, which leads to a stable superconducting cosmic string. We also show that a large electric current can flow along the string due to the Peccei-Quinn scale much higher than the electroweak scale. This large current induces a net attractive force betw…
Using the latest PandaX limits on light dark matter (DM) with light mediator, we check the implication on the parameter space of the general singlet extension of MSSM (without $Z_3$ symmetry), which can have a sizable DM self-interaction to solve the small-scale structure problem. We find that the PandaX limits can stringently constrain such a paramter space, depending on the coupling $λ$ between the singlet and doublet Higgs fields. For the singlet extension of MSSM with $Z_3$ symmetry, the so-called NMSSM, we also demonstrate the PandaX constraints on its parameter space which gives a light …
Scenarios with axion-like particles of variable masses, from the milli-eV range to ultralight, can be generated in a natural way in the context of effective field theory models with anomalous $U(1)$ gauge symmetries. They include dimension-5 operators which define a coupling of the axion to the gauge anomaly. They provide a realization, in the domain of ordinary gauge theories, of models for such particles, which evade the usual mass/coupling constraint of ordinary (Peccei-Quinn) axions and are natural dark matter candidates. As an illustration of these models, we present an overview of two of…
本文简要回顾了宇宙暗物质的超对称解释。最小超对称模型（MSSM）、次最小超对称模型（NMSSM）和近最小超对称模型（nMSSM）中的中性伴子能很好地解释暗物质遗迹密度，但PAMELA的结果在这些流行的模型中很难得到解释。在MSSM的一般单重态扩展中，PAMELA结果和残余密度都可以用类单重态中性伴子来解释。这样的类单重中性伴子湮灭为类单重希格斯玻色子，后者轻到足以主要衰变为μ子或电子，并且通过交换轻CP偶类单重希格斯玻色子玻色子，索末菲效应可以大大增强湮灭截面。在这种情况下，为了满足严格的LEP约束，类SM希格斯玻色子倾向于衰变为单态希格斯对而不是$b\bar b$，因此它将在LHC上给出多μ子信号$h_SM->aa->μ$或$h_{SM}->hh->4 a ->8 μ$。
The North American Nanohertz Observatory for Gravitational Waves (NANOGrav) collaboration has recently reported strong evidence for a stochastic process affecting the 12.5 yr dataset of pulsar timing residuals. We show that the signal can be interpreted in terms of a stochastic gravitational wave background emitted from a network of axionic strings in the early Universe. The spontaneous breaking of the Peccei-Quinn symmetry originate the axionic string network and the QCD axion, the dark matter particle in the model. We explore a non-standard cosmological model driven by an exotic scalar field…
