双希格斯偶态模型包含额外的希格斯玻色子玻色子，质量范围从几百GeV到大约1 TeV。我们研究了在未来的高亮度LHC运行中可能的实验搜索中性希格斯玻色子的$A$和$H$。除了传统的搜索模式的灵感来自超对称模型，我们讨论了两个搜索模式，这是以前没有完全解决。它们是$A\to hZ$和$A/H \to t \bar t$的衰变模式。由于对类SM希格斯玻色子玻色子和顶夸克的标记增强对象的技术，我们显示了质量达到$\sim{\cal O}(1)\,\TeV$的重中性希格斯玻色子玻色子的改进质量。这里提出的模式是补充传统的实验搜索的MSSM的动机。
英文摘要：
The two-Higgs-doublet model contains extra Higgs bosons, with mass ranges spanning from several hundred GeV to about 1 TeV. We study the possible experimental searches for the neutral Higgs bosons of $A$ and $H$ at the future high-luminosity LHC runs. Besides of the conventional search modes that are inspired by the supersymmetric models, we discuss two search modes which were not quite addressed previously. They are the decay modes of $A\to hZ$ and $A/H \to t \bar t$. Thanks to the technique of tagging boosted objects of SM-like Higgs bosons and top quarks, we show the improved mass reaches for heavy neutral Higgs bosons with masses up to $\sim{\cal O}(1)\,\TeV$. The modes proposed here are complementary to the conventional experimental searches motivated by the MSSM.
Vectorlike quarks have been shown to resolve certain long-standing discrepancies pertaining to the bottom sector. We investigate, here, the prospects of identifying the existence of a topless vectorlike doublet $(B,~Y)$, as is preferred by the electroweak precision measurements. Concentrating on single production, $viz.$ $B \bar b$ with $B \to b + Z/H$ subsequently, we find that the fully hadronic decay-channel is susceptible to discovery provided jet substructure observables are used. At the 13 TeV LHC with an integrated luminosity of 300 fb$^{-1}$, a modest value of the chromomagnetic transi…
The Higgs boson may well be a composite scalar with a finite extension in space. Owing to the momentum dependence of its couplings the imprints of such a composite pseudo Goldstone Higgs may show up in the tails of various kinematic distributions at the LHC, distinguishing it from an elementary state. From the bottom up we construct the momentum dependent form factors to capture the interactions of the composite Higgs with the weak gauge bosons. We demonstrate their impact in the differential distributions of various kinematic parameters for the $pp\rightarrow Z^*H\rightarrow l^+l^-b\bar{b}$ c…
Study of polarization of heavy particles is an important branch of research in today's collider studies. The massive $W$ boson has two types of polarization states, which usually are studied via the angular distribution of its decay products. We have studied polarization of hadronic and boosted $W$ boson using jet substructure technique at 14 TeV LHC. Two different methods, viz. N-subjettiness and Soft Drop, were used to find the subjets, which are approximately considered to be the two hadronic decay products of $W$, inside boosted $W$ jets. These subjets were then used to find the distributi…
Improving sensitivity of vectorlike top partner searches with jet substructure
Indian Institute of Technology Guwahati（印度理工学院古瓦哈提分校）；Indian Institute of Science Education and Research Kolkata（印度科学教育研究所加尔各答分校）；Indian Institute of Science Education and Research, Knowledge City, Sector 81, S. A. S. Nagar, Manauli PO 140306, Punjab, India（印度科学教育研究所旁遮普邦分校）；The Institute of Mathematical Sciences（数学科学研究所）
The existence of tiny neutrino masses and flavor mixings can be explained naturally in various seesaw models, many of which typically having additional Majorana type SM gauge singlet right handed neutrinos ($N$). If they are at around the electroweak scale and furnished with sizeable mixings with light active neutrinos, they can be produced at high energy colliders, such as the Large Hadron Collider (LHC). A characteristic signature would be same sign lepton pairs, violating lepton number, together with light jets -- $pp\to N\ell^{\pm}, \; N\to\ell^{\pm}W^{\mp}, \; W^{\mp}\to jj$. We propose a…
Simple extensions of the Standard Model (SM) with additional Right Handed Neutrinos (RHNs) can elegantly explain the existence of small neutrino masses and their flavor mixings. Collider searches for sterile neutrinos are being actively pursued currently. Heavy RHNs may dominantly decay into $W^\pm l^\pm$ after being produced at the LHC. In this paper, we consider collider signatures of heavy pseudo-Dirac neutrinos in the context of inverse seesaw scenario, with a sizable mixing with the SM neutrinos under two different flavor structures, viz., Flavor Diagonal (FD) and Flavor Non-Diagonal (FND…
Charged Slepton Flavor post the 8 TeV LHC: A Simplified Model Analysis of Low-Energy Constraints and LHC SUSY Searches
由于LHC搜索的零结果与Higgs质量一起严重限制了标准模型的最小超对称扩展，我们采用一种与模型无关的方法来研究带电slepton味.我们研究了一些简化的模型，与不同的子集slepton，电弱gauginos，和希格斯诺斯，并推导出允许slepton风味的依赖性在该地区探测目前的LHC搜索，并在该地区相关的14 TeV LHC。然后，我们研究的影响，允许的风味依赖轻子加上失踪的能量搜索。在某些情况下，风味依赖显著地修改了搜索的范围。这些效应在下一次LHC运行时可能会更大，因为对于在14 TeV探测的更高质量，更大的味道混合和相对质量分裂与低能量约束是相容的。保留完整的轻子味信息可以增加搜索的灵敏度。
An overview of the recent searches for Higgs boson pair production at the LHC was presented. The searches were based on approximately 140 $\mathrm{fb}^{-1}$ of data collected by the ATLAS and CMS experiments in proton-proton collisions at $\sqrt{s}$ = 13 TeV. With respect to the previous searches, analysis techniques were significantly improved, and new signatures and decays channels were explored.
We study the sensitivity of displaced vertex searches for heavy neutrinos produced in W boson decays in the LHC detectors ATLAS, CMS and LHCb. We also propose a new search that uses the muon chambers to detect muons from heavy neutrino decays outside the tracker. The sensitivity estimates are based on benchmark models in which the heavy neutrinos mix exclusively with one of the three Standard Model generations. In the most sensitive mass regime the displaced vertex searches can improve existing constraints on the mixing with the first two Standard Model generations by more than four orders of …
LHC searches for heavy neutral Higgs bosons with a top jet substructure analysis
在一般双Higgs模型下，研究了重$CP$ -奇希格斯玻色子$A$和重$CP$ -偶希格斯玻色子$H$的LHC搜索.具体而言，我们考虑通过$b \bar b$或$t \bar t $相关的生产渠道的$A/H\to t \bar t $的衰减模式。在所谓的“排列极限”的两个希格斯偶线模型，这种衰变模式可以是最主要的一个。通过使用HEPTopTagger和多变量分析方法，我们给出了在高亮度LHC运行中通过这些通道对$CP$ -奇希格斯玻色子$A$和$CP$ -偶希格斯玻色子$H$的搜索灵敏度.
Using two suitable benchmark scenarios that satisfy the experimental constraints on the total decay width of the $125 \, {\rm GeV}$ Higgs boson, we determine the bounds on light CP-odd spin-0 states in the 2HDM+$a$ model that arise from existing LHC searches. Our work represents the first thorough study that considers the parameter space with $m_a \lesssim 100 \, {\rm GeV}$ and should prove useful for 2HDM+$a$ interpretations of future ATLAS, CMS and LHCb searches for pseudoscalars with masses below the electroweak scale.
Using a pQCD picture for jet evolution in a dense QCD medium, in which medium-induced parton branchings are factorized from vacuum-like emissions, we study two jet substructure observables: the $z_g$ and the Soft Drop multiplicity distributions. We compute the respective nuclear modification factors using a Monte-Carlo implementation of the parton showers. Our results are in qualitative agreement with LHC data for Pb+Pb collisions. We identify the physical mechanisms explaining our results: incoherent jet energy loss, semi-hard medium-induced emissions and the bias introduced by the steeply fa…
The process $p+p\to W^\pm W^+ W^-$ with lepton decays of $W$-bosons is shown to be promising for improving conditions for studies of parameter $λ$, which is the anomalous triple $W$-bosons interaction coupling constant.
The Run 2 data taking period of the Large Hadron Collider (LHC) at CERN in years 2015-2018 has presented a great opportunity to search for physics beyond the standard model (BSM). It will be followed by the Run 3 period starting in 2022, and by the High-Luminosity LHC (HL-LHC) era starting in late 2020s, where the latter promises an unprecedented wealth of physics prospects due to very high expected integrated luminosity and improved detector features. The ATLAS, CMS and LHCb experiments pursued a rich physics program in Run 2, and are already assessing the physics expectations at the HL-LHC e…
Jet substructure observables are crucial for exploring the effects of the hot, dense medium and differentiating between quark and gluon jets. In this paper, we investigate the modification of jet shape by calculating the differential girth at LHC energies, ranging from pp to Pb--Pb collisions. The differential girth distribution exhibits a wave-like pattern, which offers a better explanation for the radial spreading of jet energy and large-angle radiation effects. We fit the differential girth distribution with a sine wave function to obtain the amplitude, angular frequency, initial phase, and…
SND@LHC is an approved experiment equipped to detect scattering of neutrinos produced in the far-forward direction at the LHC, and aimed to measure their properties. In addition, the detector has a potential to search for new feebly interacting particles (FIPs) that may be produced in proton-proton collisions. In this paper, we discuss FIPs signatures at SND@LHC considering two classes of particles: stable FIPs that may be detected via their scattering, and unstable FIPs that decay inside the detector. We estimate the sensitivity of SND@LHC to probe scattering of leptophobic dark matter, and t…
