Precision study of W~-W~+H production including parton shower effects at CERN Large Hadron Collider

The precision study of W~-W~+H production with subsequent W~±→l~±_v_l~((-)) and H→bb decays at the Large Hadron Collider(LHC) aids in the investigation of Higgs gauge couplings and the search for new physics beyond the standard model.In this study,we calculate the shower-matched next-to-leading order QCD and electroweak(EW)corrections from the qq annihilation and photon-induced channels to the W~-W~+H production at the 14 TeV LHC.We deal with the subsequent decays of Higgs and W~± bosons by adopting the MADSPIN method.Both the integrated cross section and some kinematic distributions of W~±,H,and their decay products are provided.We find that the QCD correction significantly enhances the leading-order differential cross section,while the EW correction from the qq annihilation channel obviously suppresses it,especially in the high energy phase-space region,due to the Sudakov effect.The qy-and yy-induced relative corrections are positive and insensitive to the transverse momenta of W~±,H,and their decay products.These photon-induced corrections compensate the negative qq-initiated EW correction,and become the dominant EW contribution as the increment of the pp colliding energy.The parton shower(PS) effects on kinematic distributions are not negligible.The relative PS correction to the b-jet transverse momentum distribution can exceed 100% in the high p_(T,b) region.Moreover,we investigate the scale and PDF uncertainties,and find that the theoretical error of the QCD+EW+qγ+γγ-corrected integrated cross section mainly originates from the renormalization scale dependence of the QCD correction.     

Probing anomalous top-Higgs couplings at the HL-LHC via H→WW~* decay channels

We study the prospects of probing the anomalous tHq(q=u,c)couplings via SS2L or 3L signatures at the High Luminosity(HL-LHC)run of the 14 Te V CERN collider.We focus on signals of the tH associated production followed by the decay modes t→b?~+ν_?and H→W W~*,and ■ production followed by the decay modes t→b?~+ν_?and■where?=e,μ.Based on two types of H→W W~*decay topologies,one assuming the semileptonic decay mode H→W W~*→?~+νjj and the other the fully leptonic decay mode■,we perform a full simulation for signals and backgrounds.It is shown that,at the future HL-LHC,the branching ratio Br(t→uh)(Br(t→ch))can be probed to 1.17(1.56)×10~(-3)for the same-sign di-lepton channel,and to7.1×10~(-4)(1.39×10~(-3))for the 3L channel at 3σsensitivity.     

Production and decay of the 125 GeV Higgs boson in thelittlest Higgs model with T-parity

Motivated by recent search results for the standard model (SM) Higgs boson at the Large Hadron Collider (LHC), we revisit the Higgs phenomenology in the littlest Higgs model with T-parity (LHT). We present the signal strength modifier μ, respectively, for the main search channels qq' → jjh→ jjγγ, qq'→ Vh→ Vγγ, qq'→ Vh → Vbb, gg→ h → γγ, and gg → h → VV in the LHT model. It is found that an enhancement factor of 1.09-1.56 in the qq' → jjh→ jjγγ channel can be obtained for this model in Case B with parameter f in the range 500-1000~GeV. However, the rates for bb, ττ are significantly suppressed relative to the SM predictions, which are still consistent with the current sensitivity. It is hoped that this will be further tested with larger integrated luminosity at the LHC.     

Hadronic Decays of the Spin-Singlet Heavy Quarkomium under the Principle of Maximum Conformality

The principle of maximum conformality （PMC） provides a way to eliminate the conventional renormalization scale ambiguity in a systematic way. By applying the PMC scale setting, all non-conformal terms in a perturbative series are summed into the running coupling, and one obtains a unique, scale-fixed prediction at any finite order. In this study, we make a detailed PMC analysis for the spin-singlet heavy quarkoniums decay （into light hadrons） at the next-to-leading order. After applying the PMC scale setting, the decay widths for all those cases are ahnost independent of the initial renormalization scales. The PMC scales for ηc and he decays are below 1 GeV; to achieve a confidential pQCD estimation, we adopt several low-energy running coupling models to carry out the estimation. By taking the MPT model, we obtain Г（ηc → LH） = 25.09 -4.28^＋5.52 MeV, F（ηb →LH） 14.34-0.84^＋0.92 feV, Г（hc →LH） = 0.54-0.04^＋0.06 MeV and Г（hb →LH） = 39.89-0.46^＋0.28 keV, where the errors are calculated by taking mc E[1.4OGeV, 1.60GeV] and mb C[4.50GeV, 4.70GeV]. These decay widths agree with the principle of minimum sensitivity estimations, in which the decay widths of ηc,b are also consistent with the measured ones.     

Analysis of the coupling constants g_(a_0ηπ~0) and g_(a_0η’ π~0) with light-cone QCD sum rules

In this article, we take the point of view that the light scalar meson a0(980) is a conventional qqstate, and calculate the coupling constants ga0ηπ0 and ga0ηπ0 with the light-cone QCD sum rules. The central value of the coupling constant ga0ηπ0 is consistent with that extracted from the radiative decay φ(1020) → a0(980)γ→ηπ0γ. The central value and lower bound of the decay width Γa0→ηπ0 =127+8448 MeV are compatible with the experimental data of the total decay width Γa0(980) = (50-100) MeV from the Particl...     

Precise evaluation of h→c■ and axion-like particle production

We study the decay of the SM Higgs boson to a massive charm quark pair at the next-to-next-to-leading order QCD and next-to-leading order electroweak.At the second order of QCD coupling,we consider the exact calculation of flavour-singlet contributions where the Higgs boson couples to the internal top and bottom quark.Helpful information on the running mass effects related to Yukawa coupling may be obtained by analyzing this process.High precision production for h→cc within the SM makes it possible to search for new physics that may induce relatively large interactions related to the charm quark.As an example,we evaluate the axion-like particle associate production with a charm quark pair in the Higgs decay and obtain some constraints for the corresponding parameters under some assumptions.     

A private SUSY 4HDM with FCNC in the up-sector

We present a SUSY model with four Higgs doublets of the"private type,"in which all fermion types(up,down,and charged leptons)obtain their masses from a different Higgs doublet H_f(f=u_1,d,e) .The conditions for anomaly cancellation imply that the remaining Higgs doublet of the model( H_{u_2} )must have the same hypercharge as H_{u_1} ,and thus,can only couple to up-type quarks,which opens the possibility to have FCNCs only in this sector.We study the Lagrangian of the model,and in particular,the Higgs potential,to identify the Higgs mass-eigenstates and their interactions;for the Yukawa matrices,we consider the four-texture case.We obtain constraints on the model parameters by using LHC measurements on the properties of the 125 GeV Higgs boson(h),and identify viable regions of the parameter space.Subsequently,these constraints are used to evaluate the prospects for detecting the FCNC decay mode t→ch at the future high-luminosity(HL)option for the LHC,which are compared with current limits from LHC-run2.Moreover,we evaluate the FCNC decay of the next heavier Higgs boson H₂→tc ,which can typically reach BR(H_2→tc)≈(10^-4-10^-5) .The search for the signal at HL-LHC is also studied,and it is found that it may be detectable for specific regions of the model parameter space.     

A possible explanation of the threshold enhancement in the process e~+e~-→∧■

Inspired by the recent measurement of the process e~+e~-→∧■,we calculate the mass spectrum of the 0 meson with the GI model.For the excited vector strangeonium states ?(3 S,4 S,5 S,6 S) and ?(2 D,3 D,4 D,5 D),we investigate the electronic decay width with the Van Royen-Weisskopf formula,and the partial widths of the ∧■,■,and■ decay modes with the extended quark-pair creation model.We find that the electronic decay width of the D-wave vector strangeonium is about 3～8 times larger than of the S-wave vector strangeonium.Around 2232 Me V,the partial decay width of the ∧■ mode can be up to several MeV for ?(3~3 S_1),while the partial ∧■ decay width of ?(2~3 D_1) is O(10~(-3)) keV.If the threshold enhancement reported by the BESIII collaboration arises from the strangeonium meson,this state is very likely the ?(3~3 S_1) state.We also note that the ∧■ and∑~+■partial decay widths of the states ?(3~3 D_1) and ?(4~3 S_1) are several MeV,which is sufficient to be observed in future experiments.     

Lepton-number-violating decays of singly-charged Higgs bosons in the type-(Ⅰ+Ⅱ) seesaw model

The lepton-number-violating decays of singly-charged Higgs bosons H± are investigated in the minimal type-(Ⅰ+Ⅱ) seesaw model with one SU(2)L Higgs triplet Δ and one heavy Majorana neutrino N1 at the TeV scale.We find that the branching ratios B(H+ → lα+ ν)(for α = e,μ,τ) depend not only on the mass and mixing parameters of three light neutrinos νi(for i=1,2,3) but also on those of N1.Assuming that the mass of N1 lies in the range of 200 GeV to 1 TeV,we figure out the generous interference bands for the contributions of νi and N1 to B(H+ →lα+ ν).We illustrate some salient features of such interference effects by considering three typical mass patterns of νi,and show that the relevant Majorana CP-violating phases can affect the magnitudes of B(H+ →l+αν) in this parameter region.     

Analysis of the coupling constants ga0ηπ0 and ga0η＇ π0 with light-cone QCD sum rules

In this article, we take the point of view that the light scalar meson a0（980） is a conventional qqstate, and calculate the coupling constants ga0ηπ0 and ga0ηπ0 with the light-cone QCD sum rules. The central value of the coupling constant ga0ηπ0 is consistent with that extracted from the radiative decay φ（1020） → a0（980）γ→ηπ0γ. The central value and lower bound of the decay width Γa0→ηπ0 =127＋8448 MeV are compatible with the experimental data of the total decay width Γa0（980） = （50-100） MeV from the Particle Data Group with a very model dependent estimation （the decay width can be much larger）, while the upper bound is too large. We give a possible explanation for the discrepancy between the theoretical calculation and experimental data.     

Rare Higgs three body decay induced by top-Higgs FCNC coupling in the littlest Higgs model with T-parity

Motivated by the search for flavor-changing neutral current(FCNC) top quark decays at the LHC,we calculate the rare Higgs three body decay H→Wbc induced by top-Higgs FCNC coupling in the littlest Higgs model with T-parity(LHT).We find that the branching ratio of H→Wbc in the LHT model can reach O(10~(-7)) in the allowed parameter space.     

Higgs and Bottom Quarks Associated Production at High Energy Colliders in the Littlest Higgs Model with T-Parity

In the littlest Higgs Model with T-parity,we discuss the Higgs production in association with bottom quarks at the LHC and future electron-positron collider.We calculate the cross sections of production channels pp→bb H,bb→H and bg→b H at 14 Te V LHC and the cross sections of production channel e~+e~-→bb H in(un)polarized beams at the lowest order.In order to investigate the observability,we display some typical final state distributions in the Higgs to diphoton channel.     

Analysis of the coupling constants g_(a_0ηπ~0 )and g_(a_0η'π~0) with light-cone QCD sum rules

Abstract In this article, we take the point of view that the light scalar meson a_0(980) is a conventional qq state, and calculate the coupling constants g_(a_0ηπ~0) and g_(a_0η'π~0) with the light-cone QCD sum rules. The central value of the coupling constant g_(a_0ηπ~0) is consistent with that extracted from the radiative decay φ(1020) → a_0(980)γ→ηπ~oγ. The central value and lower bound of the decay width Γ_(α_0→ηπ~0) = 127_(-48)~(+84) MeV are compatible with the experimental data of the total decay width Γ_(α_0(980))= (50-100) MeV from the Particle Data Group with a very model dependent estimation (the decay width can be much larger), while the upper bound is too large. We give a possible explanation for the discrepancy between the theoretical calculation and experimental data.     

Higgs assisted razor search for Higgsinos at a 100 TeV pp collider

A 100 Te V proton-proton collider will be an extremely effective way to probe the electroweak sector of the minimal supersymmetric standard model (MSSM).In this paper,we describe a search strategy for discovering pair-produced Higgsino-like next-to-lightest supersymmetric particles (NLSPs) at a 100 Te V hadron collider that decay to Bino-like lightest supersymmetric particles (LSPs) via intermediate Z and SM Higgs bosons that in turn decay to a pair of leptons and a pair of b-quarks respectively:■.In addition,we examine the potential for machine learning techniques to boost the power of our searches.Using this analysis,Higgsinos up to 1.4 Te V can be discovered at the 5σlevel for Binos with mass of about0.9 Te V using 3000 fb~(-1)of data.Additionally,Higgsinos up to 1.8 Te V can be excluded at 95%C.L.for Binos with mass of about1.4 Te V.This search channel extends the multi-lepton search limits,especially in the region where the mass difference between the Higgsino NLSPs and the Bino LSP is small.     

125 GeV Higgs decay with lepton flavor violation in the μνSSM

Recently,the CMS and ATLAS collaborations have reported direct searches for the 125 GeV Higgs decay with lepton flavor violation,h→μτ.In this work,we analyze the signal of the lepton flavour violating(LFV) Higgs decay h→μτ in the μ.from γ Supersyninietric Standard Model(μνSSM) with slepton flavor mixing.Simultaneously,we consider the constraints from the LFV decay τ→μγ,the muon anomalous magnetic dipole moment and the lightest Higgs mass around 125 GeV.     

Radiative decay of the Ξ(1620) in a hadronic molecule picture

Last year,the Ξ(1620) state,which is cataloged in the Particle Data Group(PDG) with only one star,was reported again in the Ξ~-π~+final state by the Belle Collaboration.Its properties,such as the spectroscopy and decay width,cannot be simply explained in the context of conventional constituent quark models.This inspires an active discussion on the structure of this resonance.In this paper,we study the radiative decays of the newly observed Ξ(1620) assuming that it is a meson-baryon molecular state of AK and with spin-parity J~P=1/2~-developed in our previous study.The partial decay widths of the AK-ΣK molecular state into Ξγ and Ξπγ final states through hadronic loops are evaluated using effective Lagrangians.The partial widths for Ξ(1620)~0→γΞ is evaluated to be approximately 118.76-174.21 keV,which may be accessible for the LHCb experiment.If Ξ(1620) is aΛK-∑K molecule,the radiative transition strength Ξ(1620)~0→γKA is considerably small and the decay width is of the order of 0.01 eV.Future experimental measurements of these processes can be useful to test the molecule interpretations of the Ξ(1620).     

Strong decays of P-wave mixing heavy-light 1~+ states

Many P-wave mixing heavy-light 1~+ states have not yet been discovered by experiment, while others have been discovered but without width information, or with large uncertainties on the widths. In this paper, the strong decays of the P-wave mixing heavy-light 1~+ states D0, D~±, D~±s, B0, B~±and Bs are studied by the improved BetheSalpeter(B-S) method with two conditions of mixing angle θ: one is θ = 35.3?; the other is considering a correction to the mixing angle θ =35.3?~+θ_1. Valuable predictions for the strong decay widths are obtained: Γ(D′01)=232 MeV,Γ(D01)=21.5 MeV, Γ(D′_1~±.)=232 MeV, Γ(D_1~±)=215 MeV, Γ(D′_(s1)~±)=0.0101 MeV, Γ(D~±s1)=0.950 MeV, Γ(B′_1~±)=263 MeV, Γ(B~±1) = 16.8 MeV, Γ(B′s1) = 0.01987 MeV and Γ(B_(s1)) = 0.412 MeV. It is found that the decay widths of D~±s1 and Bs1 are very sensitive to the mixing angle. The results will provide theoretical assistance to future experiments.     

Chargino Production via Z~0-Boson Decay in a Strong Electromagnetic Field

In the framework of MSSM the probability of Z°-boson decay to charginos in a strong electromagnetic field,Z~0→χ~+χ~-,is analyzed.The method of calculations employs exact solutions of relativistic wave equations for charginos in a crossed electromagnetic Geld.Analytic expression for the decay width Γ(Z~0→χ~+χ~-) is obtained at an arbitrary value of the parameter n=em_z~(-3)(-(F_(μυq~υ))~2)~(1/2),which characterizes the external-Geld strength F_(μυ) and Z~0-boson momentum q~υ.The process Z~0→χ~+χ~- is forbidden in a vacuum for the case of relatively heavy charginos:M_χ±mz/2.However,in an intense electromagnetic background this reaction could take place in the region of superstrong Gelds(n1).     

Detection of Charged Higgs Bosons in e~+e~-(γγ)→tφ~- Production at the ILC

In the context of the left-right twin Higgs (LRTH) model,we have studied the charged Higgs bosons production processes e~+e~-(γγ)→tφ~at the International Linear Collider (ILC).It is found that the cross sections of these two processes could reach a few fb with reasonable parameter values.With the yearly integrated luminosity of L=500 fb-1 expected at the ILC,one could collect hundreds up to thousands of charged Higgs events via these two processes.Therefore,our researches in this paper can help us search for charged Higgs bosons,and furthermore,to test the LRTH model.