We consider the decay of the Higgs boson to W$^{+}$ W$^{-}$ at a proposed Large Hadron Electron Collider and determine the likelihood of detecting a signal for the Higgs mass from its decay product W jets by imposing cuts to select candidate jet pairs and optimizing the value of the angular separation $ΔR$. It was found that at the LHeC experiment (CM energy $\sqrt{s}=1.3$ TeV and luminosity of 100 fb$^{-1}$ per year), the highest efficiency is obtained with $ΔR = 0.4$, along with a selection scheme of $|Δη| <1, 10<m<85$ GeV, $p_T$ of jets 1 and 2 between $10 - 20$ GeV and $p_T$ of jets 3 and 4 $>10$ GeV: this led to an efficiency between $7.1 - 7.5 \%$ for finding the invariant 4-jet mass in a mass region $<140$ GeV. Under signal-to-background comparison, the signal showed a $3.8 σ$ excess compared to the charged current W$^{-}$ background.
A measurement of Z production cross-section in $γe^{-}$ collision at Large Hadron-electron Collider (LHeC) is presented to compare to that at International Linear Collider (ILC). The total cross-section depends strongly on the polarization of the initial and final $e^{-}$ beams, the electron beam energy $E_{e}$ with the energy of the proton beam taken to be $E_{p} = 7$ TeV. The result shows that the total cross-section in $γe^{-} \rightarrow Z e^{-} \rightarrow l^{-}l^{+}e^{-}$ at LHeC is much larger than that at ILC.
We study the exotic decay of the 125 GeV Higgs boson ($h$) into a pair of light spin-0 particles ($ϕ$) which subsequently decays and results in a $4b$ final state. This decay mode is well motivated in the Next to Minimal Supersymmetric Standard Model (NMSSM) and extended Higgs sector models. Instead of searching at the Large Hadron Collider (LHC) and the High Luminosity Large Hadron Collider (HL-LHC) which are beset by large Standard Model (SM) backgrounds, we investigate this decay channel at the much cleaner Large Hadron Electron Collider (LHeC). With some simple selection cuts this channel …
We examine the potential of the process $ep \rightarrow eγ^{*} γ^{*} p\rightarrow eτ\barτp$ at the Large Hadron Electron Collider (LHeC) and the Future Circular Hadron Electron Collider (FCC-he) to examine non-standard $τ\barτγ$ coupling in a model independent way by means of the effective Lagrangian approach. We perform pure leptonic and semileptonic decays for $τ^{-}τ^{+}$ production in the final state. Furthermore, we use $L = 10, 50, 100, 300, 500, 1000$ fb$^{-1}$ with at $\sqrt{s}=1.30, 1.98, 7.07, 10$ TeV and we consider systematic uncertainties of $δ_{sys}=0,5,10 \%$. The best sensitivi…
Resonant Production of Sbottom via RPV Couplings at the LHeC
在LHeC对撞机上研究了超对称性的R宇称破坏相互作用中标量底的共振产生。虽然寻找超越标准模型的物理是LHC的主要任务，最近，一个$\mathit{e^{-}p}$对撞机（LHeC）的建议，以补充和解决在TeV尺度上的新现象的观察。本文研究了通过过程$\mathit{e^{-}+p\rightarrow\widetilde{b^{*}}\rightarrowμ^{-}+\bar{q}}$改进$\hat{L}\hat{Q}\hat{D}$耦合$λ_{ijk}'$约束的前景，其中$\mathit{q}$表示上型夸克。结果表明，在95% C. L条件下，对于1：fb^{-1}积分亮度，对$λ_{ijk}'$的约束可以提高到10^{-3}。与60 GeV的$\mathit{e^{-}}$束流选项的LHeC。
We study the potential of the next $ep$ collider, namely LHeC, with two options $\sqrt{s}=1.3$ TeV $\sqrt{s}=1.98$ TeV, to search for excited spin-1/2 and spin-3/2 neutrinos. We calculate the single production cross section of excited spin-1/2 and spin-3/2 neutrinos according to their effective currents describing their interactions between gauge bosons and SM leptons. We choose the $ν^{\star}\rightarrow eW$ decay mode of excited neutrinos and $W\rightarrow jj$ decay mode of $W$-boson for the analysis. We put some kinematical cuts for the final state detectable particles and plot the invariant…
As an important sequential work of the S-wave $B_c^{(*)}$ ($^1S_0(^3S_1)$) meson production at the large hadron electron collider (LHeC), we investigate the production of the P-wave excited $B_c^{**}$ states ($^1P_1$ and $^3P_J$ with $J=0,1,2$) via photoproduction mechanism within the framework of nonrelativistic QCD at the LHeC. Generally, the $e^-+P \to γ+ g \rightarrow B_c^{**} +b+ \bar{c}$ process is considered as the main production mechanism at an electron-proton collider due to the large luminosity of the gluon. However, according to our experience on the S-wave $B_c^{(*)}$ meson produc…
We study the anomalous $W^+W^-γ$ couplings in performing the production of the W-pair through the process $e^- p\,\rightarrow\,e^-γ^*γ^* p\,\rightarrow\,e^-W^+W^-p$ at the Large Hadron electron Collider (LHeC) and the Future Circular Collider-hadron electron (FCC-he). We examine the pure hadronic, the semi-leptonic and the pure leptonic decay channels of the produced W-pair. We assume the center-of-mass energies of $\sqrt{s}=1.30$ and $1.98$ TeV and the integrated luminosities of 10-100 fb$^{-1}$ for the LHeC and the center-of-mass energies of $\sqrt{s}=3.46$ and $5.29$ TeV and the integrated …
The future Large Hadron electron Collider (LHeC) would allow collisions of an intense electron beam with protons or heavy ions at the High Luminosity-Large Hadron Collider (HL-LHC). Owing to a center of mass energy greater than a TeV and very high luminosity (~1 ab{-1}), the LHeC would not only be a new generation collider for deep-inelastic scattering (DIS) but also an important facility for precision Higgs physics, complementary to pp and e+ e- colliders. Previously, it has been found that uncertainties of 0.8% and 7.4% can be achieved on the Higgs boson coupling strength to b- and c-quarks …
In this article we study the prospects of the proposed Large Hadron electron Collider (LHeC) in the search for heavy neutral scalar particles. We consider a minimal model with one additional complex scalar singlet that interacts with the Standard Model (SM) via mixing with the Higgs doublet, giving rise to a SM-like Higgs boson $h_1$ and a heavy scalar particle $h_2$. Both scalar particles are produced via vector boson fusion and can be tested via their decays into pairs of SM particles, analogously to the SM Higgs boson. Using multivariate techniques we show that the LHeC is sensitive to $h_2…
In this paper, we study the single top and Higgs associated production $\rm e^- p\rightarrow ν_e \bar{t} \rightarrow ν_e h \bar{q}(h\rightarrow b\bar{b})$ in the top-Higgs FCNC couplings at the LHeC with the electron beam energy of $E_{e}$ = 60 GeV and $E_{e}$ = 120 GeV, combination of a 7 TeV and 50 TeV proton beam. With the possibility of e-beam polarization ($p_{e}$ = 0, $\pm0.6$), we distinct the Cut-based method and the Multivariate Analysis (MVA) based method, and compare with the current experimental and theoretical limits. It is shown that the branching ratio Br $\rm(t\to uh)$ can be p…
The future Large Hadron Electron Collider (LHeC) would enable collisions of an intense electron beam with either protons or heavy ions at the High Luminosity-Large Hadron Collider (HL- LHC). With a center of mass energy greater than a TeV and a high luminosity, the LHeC would be a new-generation collider for deep-inelastic scattering (DIS) and a significant facility for precise Higgs physics, complementing pp and electron-positron colliders. Anomalous hadronic decay signatures of the Higgs Boson, such as those into three or more partons, are challenging to detect at the LHC due to high backgro…
Extensions of the Standard Model (SM) gauge group with a new $U(1)_X$ predict an additional gauge boson. Through kinetic mixing with the SM photons featured by a coupling $ε$, the ensuing so-called dark photons $γ'$, which acquire mass as a result of the breaking of the gauge group $U(1)_X$, can interact with the SM field content. These massive dark photons can therefore decay to pairs of leptons, hadrons, or quarks, depending on their mass $m_{γ'}$. In this work, we discuss searches for dark photons in the mass range around and below one GeV at the LHeC and FCC-he colliders. The signal is giv…
Sensitivity prospects for lepton-trijet signals in the $ν$SMEFT at the LHeC
Instituto de Física de Mar del Plata (IFIMAR) CONICET, UNMDP（马德普拉塔物理研究所 (IFIMAR) 阿根廷国家科学研究委员会，马德普拉塔国立大学）；Instituto de Física La Plata (IFLP) CONICET, UNLP（拉普拉塔物理研究所 (IFLP) 阿根廷国家科学研究委员会，拉普拉塔国立大学）；Instituto de Física, Facultad Ingeniería, Universidad de la República（共和国大学工程学院物理研究所）；Departamento de Física, Universidad Nacional de Mar del Plata（马德普拉塔国立大学物理系）；Instituto de Física, Facultad de Ciencias, Universidad de la República（共和国大学理学院物理研究所）
We present a phenomenological study of the single top (anti-)quark production with leptonic decays at the Large Hadron electron Collider (LHeC) at the next-to-leading-order (NLO) in QCD. We focus on various differential distributions in a fiducial region. The NLO corrections can reduce the fiducial cross section by 14%. We find the NLO predictions exhibit strong stability under scale variations for most observables considered while the scale variations at the leading-order (LO) dominated in the theoretical uncertainties. We propose a method of determining the top-quark mass using the measureme…
Profiling the Higgs boson requires the study of its non-standard decay modes. In this work we discuss the prospects of the Large Hadron electron Collider (LHeC) to detect scalar particles with masses $\gtrsim$ 10 GeV produced from decays of the Standard Model (SM) Higgs boson. These scalar particles decay mainly to bottom pairs, and in a vast portion of the allowed parameter space they acquire a macroscopic lifetime, hence giving rise to displaced hadronic vertices. The LHeC provides a very clean environment that allows for easy identification of these final states, in contrast to hadronic col…
The new vector-like top partners with charge $2/3$ are a typical feature of many new physics models beyond the Standard Model (SM). We propose a search strategy for single production of top partners $T$ focusing on both the $T\to Wb$ and $T\to th$ decay channels at the Large Hadron Electron Collider (LHeC). Our analysis is based on a simplified model in which the top partner is an $SU(2)$ singlet, with couplings only to the third generation of SM quarks. We study the observability of the single $T$ through the processes $e^{+}p \to T(\to bW^{+})\barν_{e}\to b\ell^{+}+ \not E_T^{miss}$ and $e^{…
We perform an updated analysis on the searches for the anomalous FCNC Yukawa interactions between the top quark, the Higgs boson, and either an up or charm quark ($\rm tqh,\ q=u,\ c$). We probe the observability of the FCNC top-Higgs couplings through the processes $\rm e^- p\rightarrow ν_e \bar{t} \rightarrow ν_e h \bar{q}$ (signal.I) and $\rm \ e^- p \to ν_e h b$ (singal.II) at the proposed electron proton (ep) colliders, where the Higgs boson decays to a $\rm b\bar{b}$ pair. We find that at the high luminosity (1 $\rm ab^{-1}$) ep colliders where the electrons have a polarisation of $\rm 80…
The future electron-proton collider proposals, LHeC and FCC-he, can deliver $\mathcal{O}$(TeV) center-of-mass energy collisions, higher than most of the proposed lepton accelerators, with $\mathcal{O}$(ab$^{-1}$) luminosity, while maintaining a much cleaner experimental environment as compared to the hadron machines. This unique capability of $e^- p$ colliders can be harnessed in probing BSM scenarios giving final states that look like hadronic noise at $pp$ machines. In the present study, we explore the prospects of detecting such a prompt signal having multiple soft jets at the LHeC. Such a …
We compute the exclusive electroproduction, $γ^* p \rightarrow V p$, of heavy quarkonia $V$ to NLO in the collinear factorisation scheme, which has been formally proven for this process. The inclusion of an off-shell virtuality $Q^2$ carried by the photon extends the photoproduction phase space of the exclusive heavy quarkonia observable to electroproduction kinematics. This process is relevant for diffractive scattering at HERA and the upcoming EIC, as well as at the proposed LHeC and FCC.
The measurement of the Higgs quartic coupling modifier between a Higgs boson pair and a vector boson pair, $κ_{2V}$, is expected to be achieved from vector-boson fusion (VBF) production of a Higgs boson pair. However, this process involves another unmeasured parameter, the trilinear Higgs self-coupling modifier $κ_{λ}$. A sensitivity analysis should target both parameters. Since the LHC cannot avoid the gluon fusion pollution, which becomes severe for non-SM $κ_{λ}$, an electron-proton collider is more appropriate for the comprehensive measurement. In this regard, we study the VBF production o…
We perform a search for beyond the standard model dimension-six operators relevant to the Higgs boson at the Large Hadron Electron Collider (LHeC) and the Future Circular Hadron Electron Collider (FCC-he). With a large amount of data (few ab$^{-1}$) and collisions at TeV scale, both LHeC and FCC-he provide excellent opportunities to search for the BSM effects. The study is done through the process $e^-p \to h j ν_e$ where the Higgs boson decays into a pair of $b \bar{b}$ and we consider the main sources of background processes including a realistic simulation of detector effects. For the FCC-h…
We considered the new signature of a charged Higgs boson, $pp\rightarrow H^{\pm}h\rightarrow W^{\pm}hh$, which is almost background free as the promising to study of supersymmetry at the LHC with both $\sqrt{s} = 13$ TeV and $\sqrt{s}= 14$ TeV. In the framework of MSSM model we used the latest theoretical parameter space, which is consistent with the experimental constraints from Large Hadron Collider and direct or indirect searches. In the surviving regions with the help of Pythia 8.3 and Feynhiggs programs it was found that production cross sections, $σ(pp\rightarrow H^{\pm}h)$, and Branchin…
The cross sections of $e^+e^- \rightarrow ωχ_{cJ(J=0,1,2)}$ have been measured by BESIII. We try to search for vector charmonium(-like) states $Y(4220)$, $Y(4360)$, $ψ(4415)$ and $Y(4660)$ in the $e^+e^- \rightarrow ωχ_{cJ(J=0,1,2)}$ line shapes. The $ωχ_{c0}$ mainly comes from $Y(4220)$, $ωχ_{c1}$ mainly comes from $Y(4660)$ and $ωχ_{c2}$ mainly comes from $ψ(4415)$, maybe partly comes from $Y(4360)$ or $Y(4660)$. For the charmonium(-like) states that are not significant in the $e^+e^- \rightarrow ωχ_{cJ(J=0,1,2)}$ line shape, we also give the $90\%$ confidence level upper limits on the elect…
We investigate the anomalous $W^+W^-γ$ couplings through the process $e^-e^+\,\rightarrow\,ν_e\barν_eγ$ for unpolarized and polarized electron (positron) beams at the International Linear Collider. We give the 95$\%$ Confidence Level limits on the anomalous couplings with and without the systematic uncertainties for various values of center-of-mass energies and the integrated luminosities. We show that the obtained limits on the anomalous couplings through the process $e^-e^+\,\rightarrow\,ν_e\barν_eγ$ can highly improve the current experimental limits.
We investigate the possibility of searching the lepton-flavor-violating (LFV) $τ\rightarrow μγ$ rare decay at the Super Charm-Tau Factory (CTF). By comparing the kinematic distributions of the LFV signal and the standard model (SM) background, we develop an optimized event selection criteria which can significantly reduce the background events. It is concluded that new $2 σ$ upper limit of about $1.9 \times 10^{-9}$ on $Br(τ\rightarrow μγ)$ can be obtained at the CTF, which is beyond the capability of Super-B factory in searching $τ$ lepton rare decay. Within the framework of the scalar leptoq…
We propose a new search for Dark Matter at the LHC, characteristic of scenarios beyond the Standard Model with a pseudoscalar portal between the visible and dark sectors. This search, leading to a $\bar{b} b Z( \rightarrow \ell\ell) + E_{T} \hspace{-4mm}/\hspace{2mm}$ final state, reaches large regions of parameter space not probed by Dark Matter searches via multi-jet $+ E_{T} \hspace{-4mm}/\hspace{2mm}$, searches for new scalars and flavour bounds. We show that this search could be used to test the Dark Matter origin of the gamma ray Galactic Centre excess with LHC Run 2 data.
The cross section of $e^+e^- \rightarrow ηJ/ψ$ has been measured by BESIII and Belle experiments. Fit to the $e^+e^- \rightarrow ηJ/ψ$ line shape, three resonant structures are evident. The parameters for the three resonant structures are $M_{1}=(3980\pm17\pm7)$ MeV/$c^{2}$, $Γ_{1}=(104\pm32\pm13)$ MeV; $M_{2}=(4219\pm5\pm4)$ MeV/$c^{2}$, $Γ_{2}=(63\pm9\pm3)$ MeV; $M_{3}=(4401\pm12\pm4)$ MeV/$c^{2}$, $Γ_{3}=(49\pm19\pm4)$ MeV, where the first uncertainties are statistical and the second systematic. We attribute the three structures to $ψ(4040)$, $Y(4220)$ and $ψ(4415)$ states. The branching fr…
In the littlest Higgs model with T-parity, we study associated production of a Higgs and a single top quark at the 14 TeV LHC. We focus on the Higgs to two photons decay and the semileptonic top decay channel. By performing a fast detector simulation, we find that the $thj$ search in the selected channel can excluded the top partner mass $m_{T_{+}}$ up to 805 (857) GeV for case A (case B) at $2σ$ confidence level at 14 TeV LHC with the integrated luminosity $L= 3 \rm ab^{-1}$.
We analyze the lepton flavor violating decays $τ\rightarrow Pl$ ($P=π,η,η';\;l=e,μ$) in the scenario of the minimal R-symmetric supersymmetric standard model. The prediction on the branching ratios BR$(τ\rightarrow P e)$ and BR$(τ\rightarrow P μ)$ is affected by the mass insertion parameters $δ^{13}$ and $δ^{23}$, respectively. These parameters are constrained by the experimental bounds on the branching ratios BR($τ\rightarrow e (μ) γ$) and BR($τ\rightarrow 3e(μ)$). The result shows $Z$ penguin dominates the prediction on BR($τ\rightarrow Pl$) in a large region of the parameter space. The bran…
Large top quark flavor changing through neutral currents is expected by many extensions of the standard model. Direct and indirect searches for flavor changing neutral currents (FCNC) in the top quark decays to an up type quark (up,charm) and a Higgs boson are presented. We probe the observability of the top-Higgs FCNC couplings through the process e$^-$e$^+ \rightarrow t (\rightarrow \ell ν_{\ell} b) \,\, \bar{t} (\rightarrow q H)$, where $\ell$ = e, $μ$ and $q$ reflects up and charm quarks. It is shown that the branching ratio $Br(t\rightarrow qH)$ can be probed down to $1.12\times 10^{-3}$ …
It has been known that $B \rightarrow D^{(*)} τν_τ$ are good observables in the search for the charged Higgs. The recent obervation of deviation from standard-model by almost 4$σ$ by Babar, Belle and LHCb in $R(D^{(*)})$ revived the interest in possible signal of presence of charged Higgs in these modes. But such a large deviation in the rates, where standard-model has tree level contribution, coming from a charged Higgs alone is highly unlikely. However these decay modes are good probes to search for small charged Higgs signal if we can construct sensitive observables in these modes. In this …
We have investigated the process of $Λ_b\to ΛD\bar{D}$, by taking into account the contributions from the $s$-wave $D\bar{D}$ interaction within the coupled-channel unitary approach, and the intermediate $ψ(3770)$ resonance. In addition to the peak of the $ψ(3770)$, an enhancement near the $D\bar{D}$ mass threshold is found in the $D\bar{D}$ invariant mass distributions, which should be the reflection of the $D\bar{D}$ bound state. We would like to encourage our experimental colleagues to measure the $D\bar{D}$ invariant mass distribution of the $Λ_b\to ΛD\bar{D}$ process, which is crucial to …
We search for a five-plet singly charged Higgs $H_5^\pm$ in the Georgi-Machacek model at the ep colliders. The charged Higgs bosons are produced via the $ZW^{\pm}$ fusion process $p\, e^- \to j\, e^-\, H_5^\pm$, and decay as $H_5^\pm \to Z\, W^{\pm} \to (l^+ l^-)\, (jj)$. With a detector-level simulation at the FCC-eh and LHeC, a multi-variate analysis is performed to yield limits on the production cross section times branching ratio $σ(p\, e^- \to j e^- H_5^\pm) \times {\rm BR}(H_5^\pm \to Z\, W^\pm)$ and on the model parameter $\sinθ_H$ for charged Higgs masses between 200 and 1000 GeV. The …
The study of the anomalous non-resonant $HH$ production is presented from the point of view of effective field theory (EFT) parameterization. The searches for $pp \rightarrow HH \rightarrow γγWW$, $pp \rightarrow HH \rightarrow γγbb$ and $pp \rightarrow HH \rightarrow bbbb$ processes by ATLAS experiment at the Large Hadron Collider (LHC) are reproduced. The selection efficiencies and exclusion limits on the $HH$ production cross sections for different Beyond Standard Model (BSM) EFT benchmark models are obtained using the fast Monte-Carlo simulation of the ATLAS detector.
New results on the search for $B^0_s\rightarrow μ^+μ^-$ from LHCb
利用LHCb实验，使用在$\sqrt s=8$收集的1.1\，fb $^{-1}$数据，对稀有衰变$B^0_s\rightarrow μ^+μ^-$和$B^0\rightarrow μ^+μ^-$进行搜索，TeV $ and 1.0\,fb$ ^{-1} $ of data collected at $ \sqrt s=7 $\,TeV. An excess of $ B^0_s \rightarrow μ^+μ^- $ candidates with respect to the background expectations is observed with a statistical significance of 3.5 standard deviations. A branching fraction of $ { \cal BR}（B^0_s \rightarrow μ^+μ^-）=（3.2^{+1.5}_{-1.2}）\times 10^{-9} $ is measured with an unbinned maximum likelihood fit. The measured branching fraction is in agreement with the expectation from the Standard Model. The observed n…
We compute the contribution of the decays $K_L \rightarrow π^0 Q \bar Q$ and $K^+ \rightarrow π^+ Q \bar Q$, where $Q$ is a dark fermion of the dark sector, to the measured widths for the rare decays $K^+\rightarrow π^+ ν\bar ν$ and $K_L\rightarrow π^0 ν\bar ν$. The recent experimental limit for $Γ(K^+ \rightarrow π^+ ν\bar ν)$ from NA62 sets a new and very strict bound on the dark-sector parameters. A branching ratio for $K_L \rightarrow π^0 Q \bar Q$ within the reach of the KOTO sensitivity is possible. The Grossman-Nir bound is weakened by the asymmetric effect of the different kinematic cu…
