We discuss collider signatures of (1,1)-th Kaluza-Klein (KK) mode vector bosons in the framework of two universal extra dimension model, at a future electron-positron collider. Production of the (1,1)-th KK mode of electro-weak vector bosons (B(1,1), W3(1,1)), are considered in association with a hard photon. Without caring about the decay products of those vector bosons, one can measure the masses of these particles just by looking at the photon energy distribution. Once produced these particles dominantly decay to a pair of jets or to a pair of top quarks. Thus we look for a pair of jets or a pair of top quarks in association with a photon. Upto the kinematic limit of the collider, signals from the B(1,1) production and decay in both the above mentioned channels are greater than the $5σ$ fluctuation of the Standard Model background. However, the number of events from W3(1,1) production and decay is smaller and its detection prospect is not very good.
We investigate the potential of the International Linear Collider (ILC) to probe the mechanisms of neutrino mass generation and leptogenesis within the minimal seesaw model. Our results can also be used as an estimate for the potential of a Compact Linear Collider (CLIC). We find that heavy sterile neutrinos that simultaneously explain both, the observed light neutrino oscillations and the baryon asymmetry of the universe, can be found in displaced vertex searches at ILC. We further study the precision at which the flavour-dependent active-sterile mixing angles can be measured. The measurement…
We study how effects of the CP violation can be observed indirectly by precision measurements of Higgs boson couplings at a future Higgs factory such as the international linear collider. We consider two Higgs doublet models with the softly broken discrete symmetry. We find that by measuring the Higgs boson couplings very precisely we are able to distinguish the two Higgs doublet model with CP violation from the CP conserving one.
国际直线对撞机（International Linear Collider，ILC）是一台初始质心能量为500 GeV，随后可扩展到1 TeV的正负电子对撞机，其目标是以前所未有的高灵敏度研究TeV量级的物理。主要议题包括希格斯粒子性质的精确测量，超对称粒子的研究和潜在的理论结构，如果超对称性在自然界中被实现，探索质量起源的其他可能性，以及宇宙学的联系。在许多通道中，特别是希格斯和轻子部分，ILC比LHC更敏感，并且总体上与LHC互补。在这篇简短的文章中，我们将快速了解ILC的功能。
In this work we study the production of color-neutral and singly-charged heavy leptons at the proposed International Linear Collider. We use the optimal observable technique to determine the statistical accuracy to which the coupling of such fermions to the $Z$ gauge boson (vector, axial or chiral) can be measured. We also consider a UV-complete model that contains these particles as well as a dark matter candidate, and consider some observable effects involving both; the correspondence to chargino production in supersymmetric models with heavy sleptons is briefly discussed.
Although the existence of Dark Matter (DM) has been suggested by various astrophysical observations, it has not yet been discovered today. We can assume a scenario in which the particles that account for the DM can interact with the Standard Model particles only through their couplings with the Higgs sector, the so-called Higgs-portal model. This model can be investigated by collider experiment using the invisible decay of Higgs boson. In this study, we evaluate the search ability of International Linear Collider (ILC) for invisible decay of the Higgs using International Large Detector (ILD) f…
We investigate the weak electric and magnetic dipole moments of top quark-Z boson interactions at the Large Hadron Collider (LHC) and the International Linear Collider (ILC). Their vanishingly small magnitude in the Standard Model makes these couplings ideal for probing New Physics interactions and for exploring the role of top quarks in electroweak symmetry breaking. In our analysis, we consider the production of two top quarks in association with a Z boson at the LHC, and top quark pairs mediated by neutral gauge bosons at the ILC. These processes yield direct sensitivity to top quark-Z boso…
Probing large extra dimensions with spin configuration of top quark pair production at the JLC
我们在联合直线对撞机（JLC）上用极化电子/正电子束探索大额外维度的特征。指出由于Kaluza-Klein引力子的自旋为2，自旋信息对于研究大额外维的间接信号是有用的。在$e^+ e^-$和$γγ$碰撞中产生的顶夸克对的自旋组态为寻找大额外维度的效应提供了一个独特的试验场。特别指出了前向-后向不对称性是$e^+ e^- \to t \bar{t}$过程的一个很好的探测器，并给出了一个新的对$γγ\to t \bar{t}$过程有效的不对称性观测量。
If one removes any \emph{ad hoc} symmetry assumptions, the general two Higgs doublet model should have additional Yukawa interactions independent from fermion mass generation, in general involving flavor changing neutral Higgs couplings. These extra couplings can affect the discovered Higgs boson $h$ through fermion loop contributions. We calculate the renormalized $hZZ$ coupling at one-loop level %by on-shell and minimal subtraction scheme, and evaluate the dependence on heavy Higgs boson mass and extra Yukawa coupling $ρ_{tt}$. Precision measurements at future colliders can explore the param…
We discuss a possibility that the parameter space of the two Higgs doublet model is significantly narrowed down by considering the synergy between direct searches for additional Higgs bosons at the LHC and its luminosity upgraded operation and precision measurements of the Higgs boson properties at future electron-positron colliders such as the International Linear Collider. We show that, in the case where the coupling constants of the discovered Higgs boson are slightly different from the predicted values in the standard model, most of the parameter space is explored by the direct searches of…
The observation of $t\bar th(125)$ production at the Large Hadron Collider (LHC) is the first direct measurement of the top Yukawa coupling. It opens the window on an extra top Yukawa coupling, $ρ_{tt}$, from a second Higgs doublet, without a $Z_2$ symmetry to forbid flavor changing neutral Higgs couplings. We show that $t\bar th$ and Higgs property measurements at the High Luminosity LHC can constrain the ${\rm Re}\,ρ_{tt}$--${\rm Im}\,ρ_{tt}$ parameter space that could drive electroweak baryogenesis, but the $Γ_h$ width measurement must be considerably improved beyond current projections.
The potential for probing extra neutral gauge boson mediators ($Z^\prime$) from low-energy measurements is comprehensively explored. Our study mainly focuses on $Z^\prime$ mediators present in string-inspired $E_6$ models and left-right symmetry. We estimate the sensitivities of coherent-elastic neutrino-nucleus scattering (CE$ν$NS) and neutrino-electron scattering experiments. Our results indicate that such low-energy high-intensity measurements can provide a valuable probe, complementary to high-energy collider searches and electroweak precision measurements.
Determining weak phase gamma and probing new physics in b->s transitions from B->eta(eta')K
本文给出了由衰变B->ηK，η' K $ alone. Given a large ratio between color-suppressed and color-allowed tree diagrams extracted from global ππ(K) fits, γis determined from the current data of η' K and the result is in agreement with the global Standard Model(SM) fits. However, a smaller ratio from factorization based calculations gives $ γ \sim 90^ \circ $确定Cabibbo-Kobayashi-Maskawa矩阵中弱相γ的方法。如果在η^{（'）} K模中得到的γ与从其他模或其他方法得到的γ显著不同，则可以挑出SM之外的新物理。由η' K得到的γ的有效值对新的物理贡献非常敏感，可以用来提取一类对强相贡献不大的模型的新的物理参数。
We study the prospect of probing electroweak baryogenesis driven by an extra bottom Yukawa coupling $ρ_{bb}$ in a general two Higgs doublet model via electric dipole moment (EDM) measurements and at the collider experiments. The parameter space receives meaningful constraints from 125 GeV Higgs $h$ boson signal strength measurements as well as several heavy Higgs boson searches at the Large Hadron Collider (LHC). In addition, we show that the asymmetry of the CP asymmetry of inclusive $B\to X_s γ$ decay would provide complementary probe. A discovery is possible at the LHC via $bg\to bA \to b Z…
We study how inflationary observables associated with primordial tensor modes are affected by coupling the minimal field content with an extra spin-2 particle during inflation. We work with a model that is ghost-free at the fully non-linear level and show how the new degrees of freedom modify standard consistency relations for the tensor bispectrum. The extra interacting spin-2 field is necessarily massive and unitarity dictates its mass be in the $m \gtrsim H$ range. Despite the fact that this bound selects a decaying solution for the corresponding tensor mode, cosmological correlators still …
We consider a gauged B$-$L (Baryon number minus Lepton number) extension of the Standard Model (SM), which is anomaly free in the presence of three SM singlet Right Handed Neutrinos (RHNs). Associated with the $U(1)_{\rm B-L}$ gauge symmetry breaking, the RHNs acquire Majorana masses and then with the electroweak symmetry breaking, tiny Majorana masses for the SM(-like) neutrinos are naturally generated by the seesaw mechanism. As a result of the seesaw mechanism, the heavy mass eigenstates which are mainly composed of the SM-singlet RHNs obtain suppressed electroweak interactions through smal…
We study the search for an extra scalar $S$ boson produced in association with the $Z$ boson at the International Linear Collider (ILC). The study is performed at center-of-mass energies of 250 GeV and 500 GeV based on the full simulation of the International Large Detector (ILD). In order to be as model-independent as possible, the analysis uses the recoil technique, in particular with the $Z$ boson decaying into a pair of muons. As a result, exclusion cross-section limits are given in terms of a scale factor $k$ with respect to the Standard Model Higgs-strahlung process cross section. These …
In this study, the sensitivity of future lepton colliders to WIMP dark matter is evaluated assuming WIMP pair production accompanied by a photon from initial state radiation, through which the process can be identified. A full detector simulation for the International Large Detector (ILD) concept at the International Linear Collider (ILC) is performed for a \com energy of 500\,GeV. Energy scales of up to $3$\,TeV can be tested for different effective operators for WIMP masses almost up to half the \com energy. The sensitivity benefits from the polarised beams, which can reduce the main SM back…
