To give concurrent consideration both the efficiency and the security(intensity of intractable problem) in the standard model,a chosen ciphertext secure identity-based broadcast encryption is proposed.Against the chos...To give concurrent consideration both the efficiency and the security(intensity of intractable problem) in the standard model,a chosen ciphertext secure identity-based broadcast encryption is proposed.Against the chosen ciphertext security model,by using identity(ID) sequence and adding additional information in ciphertext,the self-adaptive chosen identity security(the full security) and the chosen ciphertext security are gained simultaneously.The reduction of scheme's security is the decisional bilinear Diffie-Hellman(BDH) intractable assumption,and the proof of security shows that the proposed scheme is indistinguishable against adaptive chosen ciphertext attacks in the standard model under the decisional BDH intractable assumption.So the security level is improved,and it is suitable for higher security environment.展开更多
We study the new Z' boson as a portal for the production of Higgs bosons h_(0) and H_(0) predicted by the Bestest Little Higgs Model through Higgs-strahlung processes μ^(+)μ^(-)→(Z,Z')→Zh_(0),ZH_(0).We foc...We study the new Z' boson as a portal for the production of Higgs bosons h_(0) and H_(0) predicted by the Bestest Little Higgs Model through Higgs-strahlung processes μ^(+)μ^(-)→(Z,Z')→Zh_(0),ZH_(0).We focus on the resonant and nonresonant effects of the Zh0,ZH0signals.In our analysis,we consider the center-of-mass energies of √s=3,4,6,10,30 TeV and integrated luminosities of L=2,4,6,10,30 ab^(-1) projected for a future muon collider.The possibility of performing precision measurements for Higgs bosons h_(0) and H_(0) is very promising for the future muon collider.Furthermore,our results may be useful to the High Energy Physics community.Complementarily,we generate and provide the Feynman rules necessary for studying processes μ+μ-→(Z,Z')→Zh_(0),ZH_(0).展开更多
The spin-charge-family theory is a kind of the Kaluza-Klein theories, but with two kinds of the spin connection fields, which are the gauge fields of the two kinds of spins. The SO(13,1) representation of one kind of ...The spin-charge-family theory is a kind of the Kaluza-Klein theories, but with two kinds of the spin connection fields, which are the gauge fields of the two kinds of spins. The SO(13,1) representation of one kind of spins manifests in d = (3 + 1) all the properties of family members as assumed by the standard model;the second kind of spins explains the appearance of families. The gauge fields of the first kind, carrying the space index m = (0,...,3), manifest in d = (3 + 1) all the vector gauge fields assumed by the standard model. The gauge fields of both kinds of spins, which carry the space index (7, 8) gaining at the electroweak break nonzero vacuum expectation values, manifest in d = (3 + 1) as scalar fields with the properties of the Higgs scalar of the standard model with respect to the weak and the hyper charge ( and , respectively), while they carry additional quantum numbers in adjoint representations, offering correspondingly the explanation for the scalar Higgs and the Yukawa couplings, predicting the fourth family and the existence of several scalar fields. The paper 1) explains why in this theory the gauge fields are with the scalar index s = (5,6,7,8) doublets with respect to the weak and the hyper charge, while they are with respect to all the other charges in the adjoint representations;2) demonstrates that the spin connection fields manifest as the Kaluza-Klein vector gauge fields, which arise from the vielbeins;and 3) explains the role of the vielbeins and of both kinds of the spin connection fields.展开更多
The (extremely efficient) standard model of the elementary particles and fields makes several assumptions, which call for explanations. Any theory offering next step beyond the standard model must explain at least the...The (extremely efficient) standard model of the elementary particles and fields makes several assumptions, which call for explanations. Any theory offering next step beyond the standard model must explain at least the existence and properties of families and their members and correspondingly the existence of the scalar Higgs and the Yukawa couplings, which in this model take care of masses of fermions and weak bosons and influence the decaying properties of families. The spin-charge-family theory [1-11] is offering a possible explanation for the assumptions of the standard model—for the appearance of families and their members (for the charges of a family members), for the gauge fields, for the scalar fields—interpreting the standard model as its low energy effective manifestation. The spin-charge-family theory predicts at the low energy regime two decoupled groups of four families of quarks and leptons. The predicted fourth family waits to be observed, while the stable fifth family is the candidate to form the dark matter. In this paper properties of families are analysed. The appearance of several scalar fields, all in the bosonic (adjoint) representations with respect to the family groups, while they are doublets with respect to the weak charge, is presented, their properties discussed, it is explained how these scalar fields can effectively be interpreted as the standard model Higgs and the Yukawa couplings. The spin-charge-family theory predicts that there are no supersymmetric partners of the observed fermions and bosons.展开更多
We adopt a bottom-up Effective Field Theory(EFT)approach to derive a model-independent Veltman condition to cancel out the quadratic divergences in the Higgs mass.We show using the equivalence theorem that all the dev...We adopt a bottom-up Effective Field Theory(EFT)approach to derive a model-independent Veltman condition to cancel out the quadratic divergences in the Higgs mass.We show using the equivalence theorem that all the deviations in the Higgs couplings to the W and Z from the SM predictions should vanish.We argue based on tree-level unitarity that any new physics that naturally cancels out the quadratic divergences should be ≤19 TeV.We show that the level of fine-tuning required is unless the O(0:1%-1%) UV sector has a symmetry that forces the satisfaction of the model-independent Veltman condition,in which case all fine-tuning is eliminated.We also conjecture that,if no new physics that couples to the Higgs is observed up to~19 TeV,or if the Higgs couplings to the SM particles conform to the SM predictions,then the Higgs either does not couple to any UV sector or is fine-tuned.展开更多
The associated production of Z boson and a pair of new quarks at the Large Hadron Collider （LHC） is studied. The cross sections for both sequential fermions and vector-like fermions are presented. It is found that f...The associated production of Z boson and a pair of new quarks at the Large Hadron Collider （LHC） is studied. The cross sections for both sequential fermions and vector-like fermions are presented. It is found that for sequential fermions the cross sections can reach 1 - 10^2 /b for heavy quark mass mQ from 1000 GeV to 200 GeV. For vector-like quarks, the cross sections are suppressed by mixing parameter sin OL. Focusing on process pp → b＇b＇, we investigate the possibility of detecting the 6l 4- 2j signal. For a b＇ with light mass and a large branching ratio of b＇ → bZ, it is found that only several signal events （ parton level ） can be produced with 1000 fb^-1 integrated luminosity. Although the signal events are rare, all the final states are produced centrally and multi lepton final states are clear at hadron collider, which could be easily detected.展开更多
Motivated by the recently updated experimental measurement on Bd→μ^＋μ^- and B^-→π^-μ＋μ^- decays by CDF and Belle collaborations, we revisit these decays, as well as B^-→ρ^-μ^＋μ^- decay, within the Standa...Motivated by the recently updated experimental measurement on Bd→μ^＋μ^- and B^-→π^-μ＋μ^- decays by CDF and Belle collaborations, we revisit these decays, as well as B^-→ρ^-μ^＋μ^- decay, within the Standard Model, and evaluate the effects of a family non-universal Z＇ boson. Under the constraint from β（B- → π^-μ＋μ^-）, we find the ranges of the Z＇ couplings SLRμμ 〈 -5.2 × 10^-2 or Dμμ^LR 〈 -8.1 × 10^-2 are excluded. Within the allowed Z＇ parameters spaces, comparing with the SM predictions, we find that B（Bd→μ^＋μ^-）, B（B^-→π^-μ＋μ^-）, and B（B^-→ρ^-μ＋μ^-） could be enhanced by a factor about 226%, 245%, and 254%, respectively, by Z＇ contributions. However, they are hardly to be reduced. Furthermore, the zero crossing in the normalized forward-backward asymmetry spectrum of B^-→ρ^-μ＋μ^- decay at low dimuon mass always exists.展开更多
We present the angular distribution of the four-fold B→ρ(→ππ)µ^(+)µ^(−) and B→a_(1)(→ρ_(Ⅱ).⊥π)µ^(+)µ^(−) decays in the Standard Model and family non-universal Z'model.At the quark le...We present the angular distribution of the four-fold B→ρ(→ππ)µ^(+)µ^(−) and B→a_(1)(→ρ_(Ⅱ).⊥π)µ^(+)µ^(−) decays in the Standard Model and family non-universal Z'model.At the quark level,these decays are govered by the b→dµ^(+)µ^(−) transition.Along with different angular observables,we provide predictions of differential branching ra.tios,forward-backward asymmetry,and longitudinal polarization fractions of ρ and a_(1) mesons.Our analysis showsthat the signatures of the fimily non-universal Z’model are more distinct in the observables associated with the B→ρ(→ππ)µ^(+)µ^(−) decay than in those associated with the B→a_(1)(→ρ_(Ⅱ).⊥π)µ^(+)µ^(−) decay.Future measurements ofthe predicted angular observables,both at current and fiuture high energy colliders,will provide useful complement.ary data required to clarify the structure of the family non-universal Z' model in |△b|=△d|=1 processes.展开更多
Motivated by the recent result reported from LHC on the di-photon search from the Standard Model (SM) Higgs boson, we obtain limits on the anomalous couplings Hγγ and HZγ. We also perform a calculation at tree leve...Motivated by the recent result reported from LHC on the di-photon search from the Standard Model (SM) Higgs boson, we obtain limits on the anomalous couplings Hγγ and HZγ. We also perform a calculation at tree level of the decay widths as well as of the branching ratios for the reactions H → γγ and H → Zγ in the context of effective lagrangian for Higgs boson masses 115 ≤MH ≤ 130 GeV. We find that the decay widths and branching ratios from these reactions enhanced significantly due to the anomalous Hγγ and HZγ vertex, which would lead to measurable effects in Higgs signals at the LHC. Moreover, our results complement other studies on the channels H → γγ and H → Zγ.展开更多
With the discovery of a Higgs boson with a mass of 125 gigaelectronvolts(GeV)at the Large Hadron Collider(LHC)at CERN in 2012,the Standard Model(SM)is complete,and despite intensive searches,no new fundamental particl...With the discovery of a Higgs boson with a mass of 125 gigaelectronvolts(GeV)at the Large Hadron Collider(LHC)at CERN in 2012,the Standard Model(SM)is complete,and despite intensive searches,no new fundamental particle has been observed since then.In fact,a discovery can be challenging without a predictive new physics model because different channels and observables cannot be combined directly and unambiguously.Furthermore,without supporting indirect hints,the signal space to be searched is huge,resulting in diluted significances owing to the look-elsewhere effect.Several LHC processes with multiple leptons in the final state point towards the existence of a new Higgs boson with a mass between 140 GeV to 160 GeV decaying mostly to W bosons.While the former strongly reduces the look-elsewhere effect,the latter indicates that it could be a Higgs triplet with zero hypercharge.Within this simple and predictive extension of the SM,we simulate and combine different channels of diphoton production in association with leptons,missing energy,jets,etc...Using the full run-2 results by ATLAS,including those presented recently at the Moriond conference,an increased significance of 4 standard deviations is obtained for a≈152 GeV Higgs.Due to the previously predicted mass range,the look-elsewhere effect is negligible,and this constitutes the highest statistical evidence for a new narrow resonance obtained at the LHC.Furthermore,the model predicts a heavier-than-expected W boson,as indicated by the global electroweak fit.If further substantiated,the discovery of a new Higgs would overthrow the SM,provide a compelling case for the construction of future particle colliders,and pave the way to a novel understanding of the known shortcomings of the SM.In particular,the triplet Higgs field can lead to a strong first-order phase transition and could thus be related to the matter antimatter asymmetry in our Universe.展开更多
We report that a general principle of physical independence of mathematical background manifolds brings a replacement of common derivative operators by co-derivative ones. Then we obtain a new Lagrangian for the ordin...We report that a general principle of physical independence of mathematical background manifolds brings a replacement of common derivative operators by co-derivative ones. Then we obtain a new Lagrangian for the ordinary minimal standard model with supplementary terms containing the Lorentz invariance violation information measured by a new matrix, denoted as the Lorentz invariance violation matrix. We thus provide a new fundamental theory to study Lorentz invariance violation effects consistently and systematically.展开更多
We investigate the rare baryonic Λ_b→Λl^＋l^- decays in a non-universal Z＇ model, which is one of the wellmotivated extensions of the standard model（SM）. Considering the effects of Z-mediated flavour-changing ne...We investigate the rare baryonic Λ_b→Λl^＋l^- decays in a non-universal Z＇ model, which is one of the wellmotivated extensions of the standard model（SM）. Considering the effects of Z-mediated flavour-changing neutral currents（FCNCs） we analyse the differential decay rate, forward-backward asymmetries and lepton polarisation asymmetries for the Λb→Λl^＋l^- decays. We find significant deviations from their SM predictions, which could indicate new physics arising from the Z gauge boson.展开更多
We propose a low-scale Standard Model extension with T_(7)×Z_(4)×Z_(3)×Z_(2) symmetry that can successfully explain observed neutrino oscillation results within the 3σrange.Small neutrino masses are ob...We propose a low-scale Standard Model extension with T_(7)×Z_(4)×Z_(3)×Z_(2) symmetry that can successfully explain observed neutrino oscillation results within the 3σrange.Small neutrino masses are obtained via the linear seesaw mechanism.Normal and inverted neutrino mass orderings are considered with three lepton mixing angles in their experimentally allowed 3σranges.The model provides a suitable correlation between the solar and reactor neutrino mixing angles,which is consistent with the TM2 pattern.The prediction for the Dirac phase isδCP∈(295.80,330.0)°for both normal and inverted orderings,including its experimentally maximum value,while those for the two Majorana phases areη1∈(349.60,356.60)°,η2=0 for normal ordering andη1∈(3.44,10.37)°,η2=0 for inverted ordering.In addition,the predictions for the effective neutrino masses are consistent with the pre sent experimental bounds.展开更多
The minimal U(1)B_L extension of the Standard Model(B-L-SM)offers an explanation for neutrino mass generatio n via a seesaw mechanism;it also offers two new physics states,namely an extra Higgs bos on and a new Z'...The minimal U(1)B_L extension of the Standard Model(B-L-SM)offers an explanation for neutrino mass generatio n via a seesaw mechanism;it also offers two new physics states,namely an extra Higgs bos on and a new Z'gauge boson.The emerge nee of a second Higgs particle as well as a new Z'gauge boson,both lin ked to the breaking of a local U(1)B_L symmetry,makes the B-L-SM rather constrained by direct searches in Large Hadron Collider(LHC)experiments.We investigate the phenomenological status of the B-L-SM by confr on ting the new physics predictions with the LHC and electroweak precision data.Taking into account the current bounds from direct LHC searches,we demonstrate that the prediction for the muon(g-2)u anomaly in the B-L-SM yields at most a contribution of approximately 8.9×10^-12,which represents a tension of 3.28 standard deviations,with the current 1σuncertainty,by means of a Z'boson if its mass is in the range of 6.3 to 6.5 TeV,within the reach of future LHC runs.This means that the B-L-SM,with heavy yet allowed Z‘bos on mass range,in practice,does not resolve the tension between the observed anomaly in the muon(g-2)u and the theoretical prediction in the Standard Model.Such a heavy Z'boson also implies that the minimal value for the new Higgs mass is of the order of 400 GeV.展开更多
We propose a two-component dark matter explanation to the EDGES 21 cm anomalous signal.The heavier dark matter component is long-lived,and its decay is primarily responsible for the relic abundance of the lighter dark...We propose a two-component dark matter explanation to the EDGES 21 cm anomalous signal.The heavier dark matter component is long-lived,and its decay is primarily responsible for the relic abundance of the lighter dark matter,which is millicharged.To evade the constraints from CMB,underground dark matter direct detection,and XQC experiments,the lifetime of the heavier dark matter has to be larger than 0.1τU,whereτU is the age of the universe.Our model provides a viable realization of the millicharged dark matter model to explain the EDGES 21 cm signal,since the minimal model in which the relic density is generated via thermal freeze-out has been ruled out by various constraints.展开更多
Because both W-mass and muon g-2 can be affected by mass splittings among extra Higgs bosons(H,A,H^(±))in a two-Higgs-doublet model,we take a model with μ-τ lepton flavor violation interactions to examine the t...Because both W-mass and muon g-2 can be affected by mass splittings among extra Higgs bosons(H,A,H^(±))in a two-Higgs-doublet model,we take a model with μ-τ lepton flavor violation interactions to examine the two anomalies reported by CDFⅡ and FNAL.We obtain the following observations:(ⅰ)Combined with theoretical constraints,the CDF W-mass measurement disfavors H or A degenerating in mass with H^(±)but allows H and A to degenerate.The mass splitting between H^(±)and H/A must be larger than 10 GeV.m_(H) and m_(A) are favored to be smaller than 650 GeV for m_(H)<120 GeV and allowed to have larger values with increasing m_(H).(ⅱ)After imposing other relevant experimental constraints,there are parameter spaces that simultaneously satisfy(at the 2σ level)the CDF W-mass,FNAL muon g-2,and data on lepton universality in τ decays;however,the mass splittings among extra Higgs bosons are strictly constrained.展开更多
In this study,we implemented the type Ⅱ seesaw mechanism into the framework of the U(l)B-L gauge model.To achieve this,we added a scalar triplet,A,to the canonical particle content of the U(l)B-Lgauge model.By imposi...In this study,we implemented the type Ⅱ seesaw mechanism into the framework of the U(l)B-L gauge model.To achieve this,we added a scalar triplet,A,to the canonical particle content of the U(l)B-Lgauge model.By imposing that the U(l)B-L gauge symmetry be spontaneously broken at TeV scale,we show that the type Ⅱ seesaw mechanism is realized at an intermediate energy scale,more precisely,at approximately 109 GeV.To prevent heavy right-handed neutrinos from disturbing the mechanism,we evoke a Z2 discrete symmetry.Interestingly,as a result,we have standard neutrinos with mass around eV scale and right-handed neutrinos with mass in TeV scale,with the lightest one fulfilling the condition of dark matter.We developed all of these in this study.In addition,we show that the neutral component of Δ may perform unproblematic non-minimal inflation with loss of unitarity.展开更多
Neutral triple gauge couplings(nTGCs)are absent in the standard model effective theory up to dimension-6 operators,but could arise from dimension-8 effective operators.In this work,we study the pure gauge operators of...Neutral triple gauge couplings(nTGCs)are absent in the standard model effective theory up to dimension-6 operators,but could arise from dimension-8 effective operators.In this work,we study the pure gauge operators of dimension-8 that contribute to nTGCs and are independent of the dimension-8 operator involving the Higgs doublet.We show that the pure gauge operators generate both ZγZ^*and Zγγ^*vertices with rapid energy dependence∝E^5,which can be probed sensitively via the reaction e^+e^-→Zγ.We demonstrate that measuring the nTGCs via the reaction e^+e^-→Zγfollowed by Z→qq decays can probe the new physics scales of dimension-8 pure gauge operators up to the range(1-5)TeV at the CEPC,FCC-ee and ILC colliders with s~(1/2)=(0.25-1)TeV,and up to the range(10-16)TeV at CLIC with s~(1/2)=(3-5)TeV,assuming in each case an integrated luminosity of 5 ab~(-1).We compare these sensitivities with the corresponding probes of the dimension-8 nTGC operators involving Higgs doublets and the dimension-8 fermionic contact operators that contribute to the e^+e^-Zγvertex.展开更多
We investigate the resonant production of color octet muons in order to explore the discovery potential of Future Circular Collider（FCC）-based μp colliders.It is shown that the search potentials of μp colliders es...We investigate the resonant production of color octet muons in order to explore the discovery potential of Future Circular Collider（FCC）-based μp colliders.It is shown that the search potentials of μp colliders essentially surpass the potential of the LHC and would exceed that of the FCC pp collider.展开更多
By comparing the cross Sections for left-and right-handed electrons scattered from various unpolarized nuclear targets,the small parity-violating asymmetry can be measured.These asymmetry data probe a wide variety of ...By comparing the cross Sections for left-and right-handed electrons scattered from various unpolarized nuclear targets,the small parity-violating asymmetry can be measured.These asymmetry data probe a wide variety of important topies,including searches for new fundamental interactions and important features of nuclear structure that cannot be studied with other probes.A special feature of these experiments is that the results are interpreted with remarkably few theoretical uncertainties,which justifies pushing the experiments to the highest possible precision.To measure the small asymmetries accurately,a number of novel experimental techniques have been developed.展开更多
基金the National Natural Science Foundation of China (No.60970119)the National Basic Research Program (973) of China (No.2007CB311201)
文摘To give concurrent consideration both the efficiency and the security(intensity of intractable problem) in the standard model,a chosen ciphertext secure identity-based broadcast encryption is proposed.Against the chosen ciphertext security model,by using identity(ID) sequence and adding additional information in ciphertext,the self-adaptive chosen identity security(the full security) and the chosen ciphertext security are gained simultaneously.The reduction of scheme's security is the decisional bilinear Diffie-Hellman(BDH) intractable assumption,and the proof of security shows that the proposed scheme is indistinguishable against adaptive chosen ciphertext attacks in the standard model under the decisional BDH intractable assumption.So the security level is improved,and it is suitable for higher security environment.
文摘We study the new Z' boson as a portal for the production of Higgs bosons h_(0) and H_(0) predicted by the Bestest Little Higgs Model through Higgs-strahlung processes μ^(+)μ^(-)→(Z,Z')→Zh_(0),ZH_(0).We focus on the resonant and nonresonant effects of the Zh0,ZH0signals.In our analysis,we consider the center-of-mass energies of √s=3,4,6,10,30 TeV and integrated luminosities of L=2,4,6,10,30 ab^(-1) projected for a future muon collider.The possibility of performing precision measurements for Higgs bosons h_(0) and H_(0) is very promising for the future muon collider.Furthermore,our results may be useful to the High Energy Physics community.Complementarily,we generate and provide the Feynman rules necessary for studying processes μ+μ-→(Z,Z')→Zh_(0),ZH_(0).
文摘The spin-charge-family theory is a kind of the Kaluza-Klein theories, but with two kinds of the spin connection fields, which are the gauge fields of the two kinds of spins. The SO(13,1) representation of one kind of spins manifests in d = (3 + 1) all the properties of family members as assumed by the standard model;the second kind of spins explains the appearance of families. The gauge fields of the first kind, carrying the space index m = (0,...,3), manifest in d = (3 + 1) all the vector gauge fields assumed by the standard model. The gauge fields of both kinds of spins, which carry the space index (7, 8) gaining at the electroweak break nonzero vacuum expectation values, manifest in d = (3 + 1) as scalar fields with the properties of the Higgs scalar of the standard model with respect to the weak and the hyper charge ( and , respectively), while they carry additional quantum numbers in adjoint representations, offering correspondingly the explanation for the scalar Higgs and the Yukawa couplings, predicting the fourth family and the existence of several scalar fields. The paper 1) explains why in this theory the gauge fields are with the scalar index s = (5,6,7,8) doublets with respect to the weak and the hyper charge, while they are with respect to all the other charges in the adjoint representations;2) demonstrates that the spin connection fields manifest as the Kaluza-Klein vector gauge fields, which arise from the vielbeins;and 3) explains the role of the vielbeins and of both kinds of the spin connection fields.
文摘The (extremely efficient) standard model of the elementary particles and fields makes several assumptions, which call for explanations. Any theory offering next step beyond the standard model must explain at least the existence and properties of families and their members and correspondingly the existence of the scalar Higgs and the Yukawa couplings, which in this model take care of masses of fermions and weak bosons and influence the decaying properties of families. The spin-charge-family theory [1-11] is offering a possible explanation for the assumptions of the standard model—for the appearance of families and their members (for the charges of a family members), for the gauge fields, for the scalar fields—interpreting the standard model as its low energy effective manifestation. The spin-charge-family theory predicts at the low energy regime two decoupled groups of four families of quarks and leptons. The predicted fourth family waits to be observed, while the stable fifth family is the candidate to form the dark matter. In this paper properties of families are analysed. The appearance of several scalar fields, all in the bosonic (adjoint) representations with respect to the family groups, while they are doublets with respect to the weak charge, is presented, their properties discussed, it is explained how these scalar fields can effectively be interpreted as the standard model Higgs and the Yukawa couplings. The spin-charge-family theory predicts that there are no supersymmetric partners of the observed fermions and bosons.
基金Support by the OCEVU Labex(ANR-11-LABX-0060)the A*MIDEX project(ANR-11-IDEX-0001-02)funded by the"Investissements d'Avenir"French government program managed by the ANR。
文摘We adopt a bottom-up Effective Field Theory(EFT)approach to derive a model-independent Veltman condition to cancel out the quadratic divergences in the Higgs mass.We show using the equivalence theorem that all the deviations in the Higgs couplings to the W and Z from the SM predictions should vanish.We argue based on tree-level unitarity that any new physics that naturally cancels out the quadratic divergences should be ≤19 TeV.We show that the level of fine-tuning required is unless the O(0:1%-1%) UV sector has a symmetry that forces the satisfaction of the model-independent Veltman condition,in which case all fine-tuning is eliminated.We also conjecture that,if no new physics that couples to the Higgs is observed up to~19 TeV,or if the Higgs couplings to the SM particles conform to the SM predictions,then the Higgs either does not couple to any UV sector or is fine-tuned.
基金Supported in part by the National Science Foundation of China under Grant Nos.90503002 and 10821504by the National Basic Research Program of China under Grant No.2010CB833000
文摘The associated production of Z boson and a pair of new quarks at the Large Hadron Collider （LHC） is studied. The cross sections for both sequential fermions and vector-like fermions are presented. It is found that for sequential fermions the cross sections can reach 1 - 10^2 /b for heavy quark mass mQ from 1000 GeV to 200 GeV. For vector-like quarks, the cross sections are suppressed by mixing parameter sin OL. Focusing on process pp → b＇b＇, we investigate the possibility of detecting the 6l 4- 2j signal. For a b＇ with light mass and a large branching ratio of b＇ → bZ, it is found that only several signal events （ parton level ） can be produced with 1000 fb^-1 integrated luminosity. Although the signal events are rare, all the final states are produced centrally and multi lepton final states are clear at hadron collider, which could be easily detected.
基金Supported by the National Natural Science Foundation under Grant Nos. 11105043 and 11075059Research Fund for the Doctoral Program of Higher Education of China under Grant No. 20114104120002Startup Foundation for Doctor of Henan Normal University under Grant No. 1006
文摘Motivated by the recently updated experimental measurement on Bd→μ^＋μ^- and B^-→π^-μ＋μ^- decays by CDF and Belle collaborations, we revisit these decays, as well as B^-→ρ^-μ^＋μ^- decay, within the Standard Model, and evaluate the effects of a family non-universal Z＇ boson. Under the constraint from β（B- → π^-μ＋μ^-）, we find the ranges of the Z＇ couplings SLRμμ 〈 -5.2 × 10^-2 or Dμμ^LR 〈 -8.1 × 10^-2 are excluded. Within the allowed Z＇ parameters spaces, comparing with the SM predictions, we find that B（Bd→μ^＋μ^-）, B（B^-→π^-μ＋μ^-）, and B（B^-→ρ^-μ＋μ^-） could be enhanced by a factor about 226%, 245%, and 254%, respectively, by Z＇ contributions. However, they are hardly to be reduced. Furthermore, the zero crossing in the normalized forward-backward asymmetry spectrum of B^-→ρ^-μ＋μ^- decay at low dimuon mass always exists.
基金Supported by the Higher Education Commission of Pakistan through(NRPU/20-15142)。
文摘We present the angular distribution of the four-fold B→ρ(→ππ)µ^(+)µ^(−) and B→a_(1)(→ρ_(Ⅱ).⊥π)µ^(+)µ^(−) decays in the Standard Model and family non-universal Z'model.At the quark level,these decays are govered by the b→dµ^(+)µ^(−) transition.Along with different angular observables,we provide predictions of differential branching ra.tios,forward-backward asymmetry,and longitudinal polarization fractions of ρ and a_(1) mesons.Our analysis showsthat the signatures of the fimily non-universal Z’model are more distinct in the observables associated with the B→ρ(→ππ)µ^(+)µ^(−) decay than in those associated with the B→a_(1)(→ρ_(Ⅱ).⊥π)µ^(+)µ^(−) decay.Future measurements ofthe predicted angular observables,both at current and fiuture high energy colliders,will provide useful complement.ary data required to clarify the structure of the family non-universal Z' model in |△b|=△d|=1 processes.
文摘Motivated by the recent result reported from LHC on the di-photon search from the Standard Model (SM) Higgs boson, we obtain limits on the anomalous couplings Hγγ and HZγ. We also perform a calculation at tree level of the decay widths as well as of the branching ratios for the reactions H → γγ and H → Zγ in the context of effective lagrangian for Higgs boson masses 115 ≤MH ≤ 130 GeV. We find that the decay widths and branching ratios from these reactions enhanced significantly due to the anomalous Hγγ and HZγ vertex, which would lead to measurable effects in Higgs signals at the LHC. Moreover, our results complement other studies on the channels H → γγ and H → Zγ.
基金supported by a Professorship Grant from the Swiss National Science Foundation(PP00P21_76884)partially supported by the National Natural Science Foundation of China(11835013)。
文摘With the discovery of a Higgs boson with a mass of 125 gigaelectronvolts(GeV)at the Large Hadron Collider(LHC)at CERN in 2012,the Standard Model(SM)is complete,and despite intensive searches,no new fundamental particle has been observed since then.In fact,a discovery can be challenging without a predictive new physics model because different channels and observables cannot be combined directly and unambiguously.Furthermore,without supporting indirect hints,the signal space to be searched is huge,resulting in diluted significances owing to the look-elsewhere effect.Several LHC processes with multiple leptons in the final state point towards the existence of a new Higgs boson with a mass between 140 GeV to 160 GeV decaying mostly to W bosons.While the former strongly reduces the look-elsewhere effect,the latter indicates that it could be a Higgs triplet with zero hypercharge.Within this simple and predictive extension of the SM,we simulate and combine different channels of diphoton production in association with leptons,missing energy,jets,etc...Using the full run-2 results by ATLAS,including those presented recently at the Moriond conference,an increased significance of 4 standard deviations is obtained for a≈152 GeV Higgs.Due to the previously predicted mass range,the look-elsewhere effect is negligible,and this constitutes the highest statistical evidence for a new narrow resonance obtained at the LHC.Furthermore,the model predicts a heavier-than-expected W boson,as indicated by the global electroweak fit.If further substantiated,the discovery of a new Higgs would overthrow the SM,provide a compelling case for the construction of future particle colliders,and pave the way to a novel understanding of the known shortcomings of the SM.In particular,the triplet Higgs field can lead to a strong first-order phase transition and could thus be related to the matter antimatter asymmetry in our Universe.
基金Supported by National Natural Science Foundation of China (11021092, 10975003, 11035003)Key Grant Project of Chinese Ministry of Education (305001)
文摘We report that a general principle of physical independence of mathematical background manifolds brings a replacement of common derivative operators by co-derivative ones. Then we obtain a new Lagrangian for the ordinary minimal standard model with supplementary terms containing the Lorentz invariance violation information measured by a new matrix, denoted as the Lorentz invariance violation matrix. We thus provide a new fundamental theory to study Lorentz invariance violation effects consistently and systematically.
基金SERB,DST,Government of India for financial support(EMR/2015/000817)
文摘We investigate the rare baryonic Λ_b→Λl^＋l^- decays in a non-universal Z＇ model, which is one of the wellmotivated extensions of the standard model（SM）. Considering the effects of Z-mediated flavour-changing neutral currents（FCNCs） we analyse the differential decay rate, forward-backward asymmetries and lepton polarisation asymmetries for the Λb→Λl^＋l^- decays. We find significant deviations from their SM predictions, which could indicate new physics arising from the Z gauge boson.
文摘We propose a low-scale Standard Model extension with T_(7)×Z_(4)×Z_(3)×Z_(2) symmetry that can successfully explain observed neutrino oscillation results within the 3σrange.Small neutrino masses are obtained via the linear seesaw mechanism.Normal and inverted neutrino mass orderings are considered with three lepton mixing angles in their experimentally allowed 3σranges.The model provides a suitable correlation between the solar and reactor neutrino mixing angles,which is consistent with the TM2 pattern.The prediction for the Dirac phase isδCP∈(295.80,330.0)°for both normal and inverted orderings,including its experimentally maximum value,while those for the two Majorana phases areη1∈(349.60,356.60)°,η2=0 for normal ordering andη1∈(3.44,10.37)°,η2=0 for inverted ordering.In addition,the predictions for the effective neutrino masses are consistent with the pre sent experimental bounds.
文摘The minimal U(1)B_L extension of the Standard Model(B-L-SM)offers an explanation for neutrino mass generatio n via a seesaw mechanism;it also offers two new physics states,namely an extra Higgs bos on and a new Z'gauge boson.The emerge nee of a second Higgs particle as well as a new Z'gauge boson,both lin ked to the breaking of a local U(1)B_L symmetry,makes the B-L-SM rather constrained by direct searches in Large Hadron Collider(LHC)experiments.We investigate the phenomenological status of the B-L-SM by confr on ting the new physics predictions with the LHC and electroweak precision data.Taking into account the current bounds from direct LHC searches,we demonstrate that the prediction for the muon(g-2)u anomaly in the B-L-SM yields at most a contribution of approximately 8.9×10^-12,which represents a tension of 3.28 standard deviations,with the current 1σuncertainty,by means of a Z'boson if its mass is in the range of 6.3 to 6.5 TeV,within the reach of future LHC runs.This means that the B-L-SM,with heavy yet allowed Z‘bos on mass range,in practice,does not resolve the tension between the observed anomaly in the muon(g-2)u and the theoretical prediction in the Standard Model.Such a heavy Z'boson also implies that the minimal value for the new Higgs mass is of the order of 400 GeV.
基金Supported in part by the National Natural Science Foundation of China(11775109)。
文摘We propose a two-component dark matter explanation to the EDGES 21 cm anomalous signal.The heavier dark matter component is long-lived,and its decay is primarily responsible for the relic abundance of the lighter dark matter,which is millicharged.To evade the constraints from CMB,underground dark matter direct detection,and XQC experiments,the lifetime of the heavier dark matter has to be larger than 0.1τU,whereτU is the age of the universe.Our model provides a viable realization of the millicharged dark matter model to explain the EDGES 21 cm signal,since the minimal model in which the relic density is generated via thermal freeze-out has been ruled out by various constraints.
基金Supported by the National Natural Science Foundation of China(11975013,12105248,11821505,12075300,12075213)Peng-Huan-Wu Theoretical Physics Innovation Center(12047503)+1 种基金the Chinese Academy of Sciences Center for Excellence in Particle Physics(CCEPP)the Key Research Program of the Chinese Academy of Sciences(XDPB15)。
文摘Because both W-mass and muon g-2 can be affected by mass splittings among extra Higgs bosons(H,A,H^(±))in a two-Higgs-doublet model,we take a model with μ-τ lepton flavor violation interactions to examine the two anomalies reported by CDFⅡ and FNAL.We obtain the following observations:(ⅰ)Combined with theoretical constraints,the CDF W-mass measurement disfavors H or A degenerating in mass with H^(±)but allows H and A to degenerate.The mass splitting between H^(±)and H/A must be larger than 10 GeV.m_(H) and m_(A) are favored to be smaller than 650 GeV for m_(H)<120 GeV and allowed to have larger values with increasing m_(H).(ⅱ)After imposing other relevant experimental constraints,there are parameter spaces that simultaneously satisfy(at the 2σ level)the CDF W-mass,FNAL muon g-2,and data on lepton universality in τ decays;however,the mass splittings among extra Higgs bosons are strictly constrained.
基金Supported by Conselho Nacional de Pesquisae Desenvolvimento Cintifico-CNPq(C.A.S.P)and Coordenacao de Aperfeicoamento de Pesscal de Nivel Superi-or-CAPES(A.C.O.S and J.G.R).
文摘In this study,we implemented the type Ⅱ seesaw mechanism into the framework of the U(l)B-L gauge model.To achieve this,we added a scalar triplet,A,to the canonical particle content of the U(l)B-Lgauge model.By imposing that the U(l)B-L gauge symmetry be spontaneously broken at TeV scale,we show that the type Ⅱ seesaw mechanism is realized at an intermediate energy scale,more precisely,at approximately 109 GeV.To prevent heavy right-handed neutrinos from disturbing the mechanism,we evoke a Z2 discrete symmetry.Interestingly,as a result,we have standard neutrinos with mass around eV scale and right-handed neutrinos with mass in TeV scale,with the lightest one fulfilling the condition of dark matter.We developed all of these in this study.In addition,we show that the neutral component of Δ may perform unproblematic non-minimal inflation with loss of unitarity.
基金supported in part by United Kingdom STFC(Grant No.ST/P000258/1)in part by the Estonian Research Council via a Mobilitas Pluss grant+5 种基金in part by the TDLI distinguished visiting fellow programmesupported in part by the National Natural Science Foundation of China(Grant Nos.11675086,and 11835005)supported in part by the CAS Center for Excellence in Particle Physics(CCEPP)the National Key R&D Program of China(Grant No.2017YFA0402204)the Key Laboratory for Particle Physics,Astrophysics and Cosmology(Ministry of Education)the Office of Science and Technology,Shanghai Municipal Government(Grant No.16DZ2260200)。
文摘Neutral triple gauge couplings(nTGCs)are absent in the standard model effective theory up to dimension-6 operators,but could arise from dimension-8 effective operators.In this work,we study the pure gauge operators of dimension-8 that contribute to nTGCs and are independent of the dimension-8 operator involving the Higgs doublet.We show that the pure gauge operators generate both ZγZ^*and Zγγ^*vertices with rapid energy dependence∝E^5,which can be probed sensitively via the reaction e^+e^-→Zγ.We demonstrate that measuring the nTGCs via the reaction e^+e^-→Zγfollowed by Z→qq decays can probe the new physics scales of dimension-8 pure gauge operators up to the range(1-5)TeV at the CEPC,FCC-ee and ILC colliders with s~(1/2)=(0.25-1)TeV,and up to the range(10-16)TeV at CLIC with s~(1/2)=(3-5)TeV,assuming in each case an integrated luminosity of 5 ab~(-1).We compare these sensitivities with the corresponding probes of the dimension-8 nTGC operators involving Higgs doublets and the dimension-8 fermionic contact operators that contribute to the e^+e^-Zγvertex.
文摘We investigate the resonant production of color octet muons in order to explore the discovery potential of Future Circular Collider（FCC）-based μp colliders.It is shown that the search potentials of μp colliders essentially surpass the potential of the LHC and would exceed that of the FCC pp collider.
基金Department of Energy(DOE)under grants DE-FG02-84ER40146(PAS)DE-FG02-07ER41522(KDP).
文摘By comparing the cross Sections for left-and right-handed electrons scattered from various unpolarized nuclear targets,the small parity-violating asymmetry can be measured.These asymmetry data probe a wide variety of important topies,including searches for new fundamental interactions and important features of nuclear structure that cannot be studied with other probes.A special feature of these experiments is that the results are interpreted with remarkably few theoretical uncertainties,which justifies pushing the experiments to the highest possible precision.To measure the small asymmetries accurately,a number of novel experimental techniques have been developed.
