Mojtaba Mohammadi Najafabadi
In this article we aim to estimate the bounds on the noncommutative scale $Λ_{NC}$ and to extract the 95% exclusion contours for some $θ_{μν}$ components using the recent measurements of the top quark width and the $W$ boson polarization in top pair events from CDF experiment at Tevatron.
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One loop $β$ functions for mirror noncommutative Euclidean Yukawa sector within electroweak-scale right handed neutrinos model
本文在电弱尺度镜像右手中微子模型中构建了欧几里得非对易汤川扇区，利用Slavnov Taylor恒等式和vulcanised传播子计算出镜像费米子的一圈β函数，并通过数值求解分析了汤川耦合随重整化尺度的演化及Landau极点现象。
The noncommutative standard model apparently violates the Lorentz symmetry. We compare the Lorentz violating terms in the Higgs sector of the noncommutative standard model with their counterparts in the standard model extension. We show that the Lorentz violating parameters in the Higgs sector can be expressed directly in terms of the noncommutative parameter without any background field. The absence of the background field enhances the obtained bounds on the noncommutative parameter from the standard model extension.
In this work we propose the Z -> gamma gamma decay as a process strictly forbidden in the standard model, suitable for the search of noncommutativity of coordinates at very short distances. We computed the Z -> gamma gamma partial width in the framework of the recently proposed one-loop renormalizable gauge sector of the noncommutative standard model. New experimental possibilities at LHC are analyzed and a firm bound to the scale of noncommutativity parameter is set around 1 TeV.
We propose the Z -> gamma gamma decay, a process strictly forbidden in the standard model, as a signal suitable for the search of noncommutativity of coordinates at very short distances. We compute the Z -> gamma gamma partial widthin the framework of the recently proposed renormalizable gauge sector of the noncommutative standard model. The one-loop renormalizability is obtained for the model containing the usual six representations of matter fields of the first generation. Even more, the noncommutative part is finite or free of divergences, showing that perhaps new interaction symmetry exist…
In this article we consider theta-expanded noncommutative gauge field theory, constructed at the first order in noncommutative parameter theta, as an effective, anomaly free theory, with one-loop renormalizable gauge sector. Related phenomenology with emphasis on the standard model forbidden decays, is discussed. Experimental possibilities of Z -> gamma gamma decay are analyzed and a firm bound to the scale of the noncommutativity parameter is set around few TeV's.
The recent introduction of a deformed non-minimal version of the noncommutative Standard Model in the enveloping-algebra approach, having a one-loop renormalisable gauge sector involving a higher order gauge term, motivates us to consider the possibility of extending the fermion sector with additional deformations, i.e. higher order fermionic terms. Since the renormalisability properties of the fermion sector of the model are not yet fully known, we work with an effective fermion lagrangian which includes noncommutative higher order terms involving a contraction with the noncommutative $θ$ ten…
In this paper we study the noncommutative effects to the lepton spectrum from the decay of a polarized top quark. It is shown that the lowest contribution comes from the quadratic terms of the noncommutative parameter. The deviations from the standard model are significant for small values of the noncommutative characteristic scale. However, the charged lepton spin correlation coefficient has a remarkable deviation from the standard model from very low values of the noncommutative characteristic scale to 1 TeV.
Top quark decays before hadronization and its information transfer to final products. The top quark decays via the weak interaction, hence the azimuthal polarized decay rate is zero in the leading order of SM. Therefore the study of top quark could be taken into consideration as useful tools to search for new physics. In this paper, we calculate the decay of polarized top quark in the framework of the noncommutative standard model. We investigate the contribution of noncommutative space-time on the azimuthal polarized decay rate and spin analyzing power. Also we depict the energy spectrum for …
We study the production cross section of the $t$-channel single top quark at the LHC in the noncommutative space-time. It is shown that the deviation of the $t$-channel single top cross section from the Standard Model value because of noncommutativity is significant when $|\vecθ| \gtrsim 10^{-4}$ GeV$^{-2}$. Using the present experimental precision in measurement of the $t$-channel cross section, we apply upper limit on the noncommutative parameter. When a single top quark decays, there is a significant amount of angular correlation, in the top quark rest frame between the top spin direction a…
We consider aspects of the noncommutative approach to the standard model based on the spectral action principle. We show that as a consequence of the incorporation of the Clifford structures in the formalism, the spectral action contains an extended scalar sector, with respect to the minimal Standard Model. This may have interesting phenomenological consequences. Some of these new scalar fields carry both weak isospin and colour indexes. We calculate the new terms in spectral action due to the presence of these fields. Our analysis demonstrates that the fermionic doubling in the noncommutative…
In noncommutative geometry (NCG) the spectral action principle predicts the standard model (SM) particle masses by constraining the scalar and Yukawa couplings at some heavy scale, but gives an inconsistent value for the Higgs mass. Nevertheless, the scalar sector in the NCG approach to the standard model, is in general composed of two Higgs doublets and its phenomenology remains unexplored. In this work, we present a type-II two-Higgs-doublet model in NCG, with a SM-like Higgs mass compatible with the 125~GeV experimental value and extra scalars within the alignment limit without decoupling w…
During the last two decades Alain Connes developed Noncommutative Geometry (NCG), which allows to unify two of the basic theories of modern physics: General Relativity (GR) and the Standard Model (SM) of Particle Physics as classical field theories. In the noncommutative framework the Higgs boson, which had previously to be put in by hand, and many of the ad hoc features of the standard model appear in a natural way. The aim of this presentation is to motivate this unification from basic physical principles and to give a flavour of its derivation. One basic prediction of the noncommutative app…
We examine the electroweak gauge sector of noncommutative standard model and in particular, obtain the $\mathcal{O} \,(θ)$ Feynman rules for all quadrilinear gauge boson couplings. Surprisingly, an electroweak-chromodynamics mixing appears in the gauge sector of noncommutative standard model, where photon as well as the neutral weak boson are coupled directly to three gluons. The phenomenological perspectives of the model in $W^-W^+ \rightarrow Z Z$ scattering are studied and it is shown that there is a characteristic oscillatory behaviour in azimuthal distribution of scattering cross sections…
The triple neutral gauge boson and direct U(1)_Y-neutrino interactions, being absent in ordinary field theory, can arise quite naturally in noncommutative gauge field theories. Using non-perturbative methods and a Seiberg-Witten map based covariant approach to noncommutative gauge theory, we have found theta-exact expressions for both interactions, thereby eliminating previous restrictions to low-energy phenomena. In particular we obtain for the first time the covariant, theta-exact, triple neutral gauge boson interactions within the noncommutative Standard Model gauge sector including an addi…
Top-quark pair production in electron-positron collisions within the minimal noncommutative Standard Model
本文研究了在最小非交换标准模型框架下电子-正电子碰撞中顶夸克对的产生，通过Seiberg-Witten映射引入非交换效应，并计算了$e^+e^-\to t\bar{t}$过程的平方截面，直至非交换参数$\Theta^{\mu\nu}$的二次项。研究得出了总截面、极角和方位角分布以及反向不对称性，这些结果对时空非交换性敏感。数值结果评估了未来线性对撞机如ILC和CLIC相关的总能量。分析表明，非交换几何可以引起显著偏离标准模型预测的特征，为高能$e^+e^-$$碰撞提供间接探测时空非交换性的可能性。
On noncommutative spacetime, the Standard Model allows new, usually Standard Model forbidden, triple gauge boson interactions. In this letter we propose the Standard Model strictly forbidden Z -> gamma gamma and Z -> gg decay modes coming from the gauge sector of the Noncommutative Standard Model as a place where noncommutativity could be experimentally discovered.
The hybrid gauge transformation and its nontrivial phenomenological implications are investigated using the noncommutative gauge theory with the Seiberg-Witten map expanded scenario. Particularly, the $e^+e^- \toμ^+ μ^-$ process is studied with a generalized noncommutative standard model (NCSM) including massive neutrinos and neutrino-photon interaction. In this model, the hybrid gauge transformation in the lepton sector is naturally introduced through the requirement of gauge invariance of the seesaw neutrino mass term. It is shown that in the NCSM without hybrid gauge transformation the nonc…
Noncommutative spectral geometry succeeds in explaining the physics of the Standard Model of electroweak and strong interactions in all its details as determined by experimental data. Moreover, by construction the theory lives at very high energy scales, offering a natural framework to address early universe cosmological issues. After introducing the main elements of noncommutative spectral geometry, I will summarise some of its cosmological consequences and discuss constraints on the gravitational sector of the theory.
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