Connecting muon anomalous magnetic moment and multi-lepton anomalies at LHC

In a previous paper by several of the authors a number of predictions were made in a study pertaining to the anomalous production of multiple leptons at the Large Hadron Collider(LHC). Discrepancies in multi-lepton final states have become statistically compelling with the available Run 2 data. These could be connected with a heavy boson, H, which predominantly decays into a standard model Higgs boson, h, and a singlet scalar, S, where m H≈270 GeV and m_S≈150 GeV. These can then be embedded into a scenario where a two-Higgs-doublet is considered with an additional singlet scalar, 2HDM+S. The long-standing discrepancy in the muon anomalous magnetic moment,?a_μ, is interpreted in the context of the 2HDM+S type-II and type-X, along with additional fermionic degrees of freedom. The 2 HDM+S model alone, with constraints from the LHC data, does not seem to explain the ?a_μ anomaly.However, adding fermions with mass of order O(100) GeV can explain the discrepancy for sufficiently low values of fermion-scalar couplings.     

Probing the flavor-specific scalar mediator for the muon(g-2)deviation,the proton radius puzzle and the light dark matter production

Flavor-specific scalar bosons exist in various Standard Model extensions and couple to a single generation of fermions via a global flavor symmetry breaking mechanism. Given this strategy, we propose a Me V flavor-specific scalar model in dimension-5 operator series, which explains the muon g-2 anomaly and proton radius puzzle by coupling with the muon and down-quark at the same time. The framework is consistent with the null result of high-intensity searches. Specifically, the supernova constraints for muon couplings become weakened by including the contribution of down-quark interaction. The parameter space for explaining muon g-2 discrepancy is available when 10% energy deposition is required in the energy explosion process in the supernova,but this is ruled out by the 1% energy deposition requirement. We also investigate the searches for mediator and dark matter and the resulting constraints on viable parameter space such as nuclear physics constraints, direct detection for light boosted dark matter, and possible CMB constraints. When compared with conventional dark matter production, light dark matter production has two additional modifications: bound state formation and early kinetic equilibrium decoupling. We are now looking into the implications of these effects on the relic density of light dark matter.     

The semi-constrained NMSSM in light of muon g-2,LHC,and dark matter constraints

The semi-constrained NMSSM(scNMSSM) extends the MSSM by a singlet field, and requires unification of the soft SUSY breaking terms in the squark and slepton sectors, while it allows that in the Higgs sector to be different. We try to interpret the muon g-2 in the sc NMSSM, under the constraints of 125 Ge V Higgs data, B physics,searches for low and high mass resonances, searches for SUSY particles at the LHC, dark matter relic density by WMAP/Planck, and direct searches for dark matter by LUX, XENON1T, and PandaX-II. We find that under the above constraints, the sc NMSSM can still(i) satisfy muon g-2 at 1σ level, with a light muon sneutrino and light chargino;(ii) predict a highly-singlet-dominated 95 GeV Higgs, with a diphoton rate as hinted at by CMS data,because of a light higgsino-like chargino and moderate λ;(iii) get low fine tuning from the GUT scale with smallμeff, M_0, M_(1/2), and A_0, with a lighter stop mass which can be as low as about 500 GeV, which can be further checked in future studies with search results from the 13 TeV LHC;(iv) have the lightest neutralino be singlino-dominated or higgsino-dominated, while the bino and wino are heavier because of high gluino bounds at the LHC and universal gaugino conditions at the GUT scale;(v) satisfy all the above constraints, although it is not easy for the lightest neutralino, as the only dark matter candidate, to get enough relic density. Several ways to increase relic density are discussed.     

Measurement of the pion form factor for M_(ππ)～2 between 0.1 and 0.85 GeV~2 with the KLOE detector

The KLOE experiment at the φ-factory DAΦNE has measured the pion form factor in the range between 0.1M_(ππ)～2 0.85 GeV2 using events taken at s～(1/2)=1 GeV with a photon emitted at large polar angles in the initial state.This measurement extends the M_(ππ)～2 region covered by KLOE ISR measurements of the pion form factor down to the two pion production threshold.The value obtained in this measurement of the dipion contribution to the muon anomalous magnetic moment of aμππ =(478.5±2.0stat±4.8syst±2.9theo)·10-10 further confirms the discrepancy between the Standard Model evaluation for aμ and the experimental value measured by the(g-2) collaboration at BNL.     

Can VMD improve the estimate of the muon g－2?

We show that a VMD based theoretical input allows for a significantly improved accuracy for the hadronic vacuum polarization of the photon which contributes to the theoretical estimate of the muon g-2.We also show that the only experimental piece of information in the τ decay which cannot be accounted for within this VMD framework is the accepted value for Br(τ→ππντ),while the τ spectum lineshape is in agreement with expectations from e+e-annihilations.     

Can VMD improve the estimate of the muon g－2?

We show that a VMD based theoretical input allows for a significantly improved accuracy for the hadronic vacuum polarization of the photon which contributes to the theoretical estimate of the muon g-2. We also show that the only experimental piece of information in the τ decay which cannot be accounted for within this VMD framework is the accepted value for Br（τ→ππvτ）, while the T spectum lineshape is in agreement with expectations from e^＋e^- annihilations.     

Non-Born-Oppenheimer study of the muonic molecule ion 4Heμ^+

Accurate non-Born-Oppenheimer variational calculations of all bound states of the positive muon molecular ion 4Heμ^+ have been performed using explicitly correlated Gaussian functions in conjunction with the global vectors.All the energies obtained are accurate in the order of 10-6 Hartree(1 Hartree=27.2114 eV).Compared with the binding energies obtained from calculations based on the Born-Oppenheimer potential with the mass-weighted adiabatic corrections(Chem.Phys.Lett.110487(1984)),the largest relative deviation is up to 15%.By analyzing the average interparticle distances and possibility distributions of interparticle distances of this system,it is confirmed that the Born-Oppenheimer approximation is reasonable for this system and that 4Heμ^+ can be regarded as a system of positive muon bound to a slightly distorted helium atom.     

Is X(3872) a bound state?

All existing experimental evidence for the bound state nature of X(3872) relies on observing its decay products,which are measured with a finite experimental mass resolution that is typically △m≥2 MeV,and much larger than its alleged binding energy,B_X=0.00(18) MeV.On the other hand,we have found recently that there is a clear cancellation in the 1~(++) channel of the invariant DD~*mass around the threshold between continuum and the bound state.This is very much like a similar cancellation in the proton-neutron continuum with the deuteron in the1~(++) channel.Based on comparative fits with a common Tsallis distribution of the experimental cross-sections for prompt production of deuterons and X(3872) in pp collisions with a finite p_T,we find a strong argument for questioning the bound state nature of this state,which also suggests that the large observed production rate could be consistent with a half-bound state.     

New g－2 experiment at J-PARC

A new measurement of the anomalous magnetic moment of the positive muon αμ is proposed with a novel technique utilizing an ultra-cold muon beam accelerated to 300 MeV/c and a 66 cm-diameter muon storage ring without focusing-electric field. This measurement will be complimentary to the previous measurement that achieved 0.54 ppm accuracy with the magic energy of 3.1 GeV in a 14 m diameter storage ring. The proposed experiment aims to achieve the sensitivity down to 0.1 ppm.     

Study of diphoton decays of the lightest scalar Higgs boson in the Next-to-Minimal Supersymmetric Standard Model

The CMS and ATLAS experiments at the LHC have announced the discovery of a Higgs boson with mass at approximately 125 GeV/c² in the search for the Standard Model Higgs boson via, notably, the γγ and ZZ to four leptons final states. Considering the recent results of the Higgs boson searches from the LHC, we study the lightest scalar Higgs boson h₁ in the Next-to-Minimal Supersymmetric Standard Model by restricting the next-to-lightest scalar Higgs boson h₂ to be the observed to the 125 GeV/c² state. We perform a scan over the relevant NMSSM parameter space that is favoured by low fine-tuning considerations. Moreover, we also take the experimental constraints from direct searches, B-physics observables, relic density, and anomalous magnetic moment of the muon measurements, as well as the theoretical considerations, into account in our specific scan. We find that the signal rate in the two-photon final state for the NMSSM Higgs boson h₁ with the mass range from about 80 GeV/c² to about 122 GeV/c² can be enhanced by a factor of up to 3.5 when the Higgs boson h₂ is required to be compatible with the excess from latest LHC results. This motivates the extension of the search at the LHC for the Higgs boson h₁ in the diphoton final state down to masses of 80 GeV/c², particularly with the upcoming proton-proton collision data to be taken at center-of-mass energies of 13-14 TeV.     

NEW MESON MASS RELATION AND LOWEST PSEUDOSCALAR GLUEBALL MASS

After considering its mixing with the glueball, we give a new mass relation for the meson nonet. According to this mass relation and the predicted mass of the pseudoscalar glueball given by lattice calculations and the effective Hamiltonian, the expected mass of the mixed pseudoscalar glueball is about 1.7 GeV. This result is helpful in the experimental search for the mixed isoscalar pseudoscalar glueball. η(1760) is discussed as a possible candidate for this type of particle.     

Measurement of the pion form factor for Mππ^2 between 0.1 and 0.85 GeV2 with the KLOE detector

The KLOE experiment at the φ-factory DAФPNE has measured the pion form factor in the range between 0.1 〈 Mππ^2 〈 0.85 GeV^2 using events taken at √s = 1 GeV with a photon emitted at large polar angles in the initial state. This measurement extends the Mππ^2 region covered by KLOE ISR measurements of the pion form factor down to the two pion production threshold. The value obtained in this measurement of the dipion contribution to the muon anomalous magnetic moment of △αμ^ππ= （478.5±2-0stat±4.8syst±2.9theo）·10^-10 further confirms the discrepancy between the Standard Model evaluation for αμ and the experimental value measured by the （g-2） collaboration at BNL.     

New g-2 experiment at J-PARC

A new measurement of the anomalous magnetic moment of the positive muon aμ is proposed with a novel technique utilizing an ultra-cold muon beam accelerated to 300 MeV/c and a 66 cm-diameter muon storage ring without focusing-electric field.This measurement will be complimentary to the previous measurement that achieved 0.54 ppm accuracy with the magic energy of 3.1 GeV in a 14 m diameter storage ring.The proposed experiment aims to achieve the sensitivity down to 0.1 ppm.     

Joint explanation of W-mass and muon g–2 in the 2HDM

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 u-r lepton flavor violation interactions to examine the two anomalies reported by CDF Ⅱ 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...     

Is Ds（2700） a charmed tetraquark state？

In this article, we assume that the Ds(2700) is a tetraquark state, which consists of a scalar diquark and a vector antidiquark, and calculate its mass with the QCD sum rules. The numerical result indicates that the mass of the vector charmed tetraquark state is about MV = (3.75±0.18) GeV or MV = (3.71±0.15) GeV from different sum rules, which is about 1 GeV larger than the experimental data. Such tetraquark component should be very small in the Ds(2700).     

What can a heavy U(1)B-L Z'boson do to the muon(g-2)u anomaly and to a new Higgs boson mass?

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.     

The Buchdahl stability bound in Eddington-inspired Born-Infeld gravity

We give the Buchdahl stability bound in Eddington-inspired Born-Infeld(EiBI)gravity.We show that this bound depends on an energy condition controlled by the model parameter K.From this bound,we can constrain κ≤10~8 m~2 if a neutron star with a mass around 3 M is observed in the future.In addition,to avoid the potential pathologies in EiBI,a Hagedorn-like equation of state associated with κ at the center of a compact star is inevitable,which is similar to the Hagedorn temperature in string theory.     

X(16.7) as the solution of the NuTeV anomaly

A recent experimental study of excited8 Be decay to its ground state revealed an anomaly in the angular distribution of the final states. This exceptional result is attributed to a new vector gauge boson X(16.7). We study the significance of this new boson, especially its effect in anomalies observed in long-lasting experimental measurements.By comparing the discrepancies between the Standard Model predictions and the experimental results, we find the values and regions of the couplings of X(16.7) to the muon and muon neutrino. In this work, we find that the newly observed boson X(16.7) may be the solution of both the Nu Te V anomaly and the(g-2)_μ puzzle.     

Revisiting the determining fraction of glueball component in f_0 mesons via radiative decays of J/ψ

QCD theory predicts the existence of glueballs,but so far all experimental endeavors have failed to identify any such states.To remedy this discrepancy between QCD,which has proven to be a successful theory for strong interactions,and the failure of experimental searches for glueballs,one is tempted to accept the promising interpretation that the glueballs mix with regular qq states of the same quantum numbers.The lattice estimate of the masses of pure 0~(++) glueballs ranges from 1 to 2 GeV,which is the region of the f_0 family.Thus many authors suggest that the f_0 mesonic series is an ideal place to study possible mixtures of glueballs and qq.In this paper,following the strategy proposed by Close,Farrar and Li,we try to determine the fraction of glueball components in f_0 mesons using the measured mass spectra and the branching ratios of J/ψ radiative decays into f_0 mesons.Since the pioneering papers by Close et al.,more than 20 years have elapsed and more accurate measurements have been done by several experimental collaborations,so it is time to revisit this interesting topic using new data.We suppose f_0(500) and f_0(980) to be pure quark states,while for f_0(1370),f_0(1500) and f_0(1710),to fit both the experimental data of J/ψ radiative decay and their mass spectra,glueball components are needed.Moreover,the mass of the pure 0~(++) glueball is phenomenologically determined.     

What can a heavy U(1)_(B-L) Z' boson do to the muon(g-2)_μ anomaly and to a new Higgs boson mass?

The minimal U(1)_(B-L) extension of the Standard Model(B-L-SM) offers an explanation for neutrino mass generation via a seesaw mechanism;it also offers two new physics states,namely an extra Higgs boson and a new Z' gauge boson.The emergence of a second Higgs particle as well as a new Z' gauge boson,both linked 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 confronting 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)_μ 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 current1σ uncertainty,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' boson mass range,in practice,does not resolve the tension between the observed anomaly in the muon(g-2)_μ 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.