A coherent study of $e^{+}e^{-}$ annihilation into two ($π^{+}π^{-}$,$K^{+}K^{-}$) and three ($π^{+}π^{-}π^{0},π^{+}π^{-}η$) pseudoscalar meson production is carried out within the framework of resonance chiral theory in energy region $E\lesssim 2 \, \mathrm{GeV}$. The work of {[}L. Y. Dai, J. Portolés, and O. Shekhovtsova, Phys. Rev. D 88,056001 (2013){]} is revisited with the latest experimental data and a joint analysis of two pseudoscalar meson production. Hence, we evaluate the lowest order hadronic vacuum polarization contributions of those two and three pseudoscalar processes to the anomalous magnetic moment of the muon. We also estimate some higher-order additions led by the same hadronic vacuum polarization. Combined with the other contributions from the standard model, the theoretical prediction differs still by $(21.6 \pm 7.4)\times 10^{-10}$ (2.9$σ$) from the experimental value.
We study, at leading order in the large number of colours expansion and within the Resonance Chiral Theory framework, the odd-intrinsic-parity $e^+ e^- \rightarrow π^+ π^- (π^0, η)$ cross-sections in the energy regime populated by hadron resonances, namely $3 \, m_π \lsim E \lsim 2 \, \mbox{GeV}$. In addition we implement our results in the Monte Carlo generator PHOKHARA 7.0 and we simulate hadron production through the radiative return method.
We investigate the possibility to constrain the pion distribution amplitude from the gamma* gamma* -> pi transition. For a surprisingly large range in the two photon virtualities we find that the transition form factor is essentially independent of the distribution amplitude. This in turn entails a parameter-free prediction of QCD. The gamma* gamma* -> eta, eta' form factors are also briefly discussed. We estimate that experimental studies might be feasible at the existing e+ e- experiments BaBar, Belle, and CLEO.
On the basis of the perturbative QCD and the relativistic quark model we investigate the relativistic and bound state effects in the production processes of a pair of $S$-wave doubly heavy mesons with opposite charge conjugation consisting of $b$ and $c$ quarks. All possible relativistic corrections in the production amplitude including the terms connected with the transformation law of the bound state wave function to the reference frame of the moving pseudoscalar ${\cal P}-$ and vector ${\cal V}-$ mesons are taken into account. We obtain a growth of the cross section for the reaction $e^++e^…
We study the production of charmed mesons (D, D_s) in antiproton-proton annihilation close to the reaction thresholds. The elementary charm production process is described by baryon exchange and in the constituent quark model, respectively. Effects of the interactions in the initial and final states are taken into account rigorously. The calculations are performed in close analogy to our earlier study on pbarp to KbarK by connecting the processes via SU(4) flavor symmetry. Our predictions for the DDbar production cross section are in the order of 10^{-2} -- 10^{-1} mu b. They turned out to be …
In this paper the dynamical spin effects of the light-front holographic wavefunctions for light pseudoscalar mesons are studied using two different assumptions. These improved wavefunctions are then confronted with a number of sensitive hadronic observables: the decay constants of $π$ and $K$ mesons, their $ξ$-moments, the pion-to-photon transition form factor, and the pure annihilation $\bar{B}_{s}\to π^+ π^-$ and $\bar{B}_{d}\to K^+K^-$ decays. Taking $f_π$, $f_{K}$ and their ratio $f_{K}/f_π$ as constraint conditions, the $χ^2$ analyses for holographic parameters, including the mass scale p…
Central pseudoscalar production in $pp$ scattering is suppressed at small values of $Q_\perp$, where $Q$ is defined as the difference between the momenta transferred from the two protons. Such a behaviour is expected if the production occurs through the fusion of two vectors. Photon exchange could provide the dominant contribution at low transferred momenta, but we argue that an extension of the experiment could probe the gluon contribution to the proton spin.
In this paper we extend our analyses of the decay constant and distribution amplitude with an improved holographic wavefunction to the heavy-light pseudoscalar mesons. In the evaluations, the helicity-dependence of the holographic wavefunction is considered; and an independent mass scale parameter is employed to moderate the strong suppression induced by the heavy quark. Under the constraints from decay constants and masses of pseudoscalar mesons, the $χ^2$-analyses for the holographic parameters exhibit a rough consistence with the results obtained by fitting the Regge trajectory. With the fi…
We explore a simple extension to the Standard Model containing two gauge singlets: a Dirac fermion and a real pseudoscalar. In some regions of the parameter space both singlets are stable without the necessity of additional symmetries, then becoming a possible two-component dark matter model. We study the relic abundance production via freeze-out, with the latter determined by annihilations, conversions and semi-annihilations. Experimental constraints from invisible Higgs decay, dark matter relic abundance and direct/indirect detection are studied. We found three viable regions of the paramete…
We calculate neutrino emissivities from self-annihilating dark matter ($χ$) in the dense and hot stellar interior of a (proto)neutron star. Using a model where dark matter interacts with nucleons in the stellar core through a pseudoscalar boson ($a$) we find that the neutrino production rates from the dominant reaction channels $χχ\rightarrow ν\barν$ or $χχ\rightarrow a a$, with subsequent decay of the mediator $ a \rightarrow ν\barν$, could locally match and even surpass those of the standard neutrinos from the modified nuclear URCA processes at early ages. We find that the emitting region ca…
An excess in $γ$-rays emanating from the galactic centre has recently been observed in the Fermi-LAT data. We investigate the new exciting possibility of fitting the signal spectrum by dark matter annihilating dominantly to a Higgs-pseudoscalar pair. We show that the fit to the $γ$-ray excess for the Higgs-pseudoscalar channel can be just as good as for annihilation into bottom-quark pairs. This channel arises naturally in a full model such as the next-to-minimal supersymmetric Standard Model (NMSSM) and we find regions where dark matter relic density, the $γ$-ray signal and other experimental…
We calculate cross sections of a pair $B_c$ meson production on the basis of two-photon mechanism from electron-positron annihilation. We investigate the production cross sections in nonrelativistic approximation and with the account of relativistic corrections. Relativistic production amplitudes of S-wave pair pseudoscalar, vector and pseudoscalar+vector $B_c$-mesons are constructed on the basis of relativistic quark model. Numerical values of the production cross sections are obtained at different center-of-mass energies. The comparison of one-photon and two-photon annihilation contributions…
Relativistic corrections to the pair $B_c$-meson production in $e^+e^-$-annihilation are calculated. We investigate a production of pair pseudoscalar, vector and pseudoscalar+vector $B_c$-mesons in the leading order perturbative quantum chromodynamics and relativistic quark model. Relativistic expressions of the pair production cross sections are obtained. Their numerical evaluation shows that relativistic effects in the production amplitudes and bound state wave functions three times reduce nonrelativistic results at the center-of-mass energy s=22 GeV.
In this work, we introduce an extra singlet pseudoscalar into the Type-III two Higgs doublet model (2HDM) which is supposed to solve a series of problems in the modern particle-cosmology. With existence of a light pseudoscalar, the $h\rightarrowμτ$ excess measured at CMS and as well as the $(g-2)_μ$ anomaly could be simultaneously explained within certain parameter spaces that can also tolerate the data on the flavor-violating processes $τ\rightarrowμγ$ and Higgs decay gained at LHC. Within the same parameter spaces, the DM relic abundance is well accounted. Moreover, the recently observed Gal…
COMPASS is a fixed-target experiment at CERN SPS which focused on light-quark meson spectroscopy during the data-taking periods in 2008 and 2009. The central exclusive production of glueball candidates is studied with a 190GeV/c proton beam impinging on a liquid hydrogen target. We select centrally produced systems with two pseudo-scalar mesons in the final state. The decay of this system is decomposed in terms of partial waves, with particular attention paid to the inherent mathematical ambiguities of the amplitude analysis. We show that simple parametrisation are able to describe the mass de…
We investigate the nonleptonic decay of charmed meson into two pseudoscalar mesons using the vector--dominance model, and compare the results with those obtained from the factorization model. In particular, we discuss the role of the annihilation diagrams in the two models.
In this letter we examine the production channels for the scalar or pseudoscalar Higgs plus two jets at the CERN Large Hadron Collider (LHC). We identify possible signals for distinguishing between a scalar and a pseudoscalar Higgs boson.
The first AMS-02 measurement confirms the existence of an excess in the cosmic-ray positron fraction previously reported by the PAMELA and Fermi-LAT experiments. If interpreted in terms of thermal dark matter (DM) annihilation, the AMS-02 result still suggests that the DM annihilation cross section in the present day should be significantly larger than that at freeze out. The Sommerfeld enhancement of DM annihilation cross section as a possible explanation for the observed excesses is subject to constraint from the DM thermal relic density, mainly due to the annihilation of DM particles into f…
We compute the total cross-section for direct production of the pseudoscalar Higgs boson in hadron collisions at next-to-next-to-leading order (NNLO) in perturbative QCD. The O(alpha_s^2) QCD corrections increase the NLO production cross-section by approximately 20-30 per cent.
Nonleptonic decays of charmed mesons into two pseudoscalar mesons or one pseudoscalar meson and one vector meson are studied on the basis of a generalized factorization method considering the resonance effects in the pole model for the annihilation contributions. Large strong phases between different topological diagrams are considered in this work, simply taking the phase in the coefficients $a_i$. We find that the annihilation-type contributions calculated in the pole model are large in both of the $PP$ and $PV$ modes, which make our numerical results agree with the experimental data better …
Pseudoscalar and charged Higgs bosons production in the processes $μ^+ μ^-\to P^0_i Z^0$, $μ^+μ^- \to H^{\pm}W^{\mp}$ within the models with several Higgs doublets and singlets is considered.
We consider the production of a Higgs pseudoscalar accompanied by two jets in hadronic collisions. We work in the limit that the top quark is much heavier than the Higgs pseudoscalar and use an effective Lagrangian for the interactions of gluons with the pseudoscalar. We compute the amplitudes involving: 1) four gluons and the pseudoscalar, 2) two quarks, two gluons and the pseudoscalar and 3) four quarks and the pseudoscalar. We find that the pseudoscalar amplitudes are nearly identical to those for the scalar case, the only differences being the overall size and the relative signs between te…
Recently obtained NNLO exact corrections for Higgs and Pseudoscalar Higgs boson production in hadron colliders are compared with approximate ones. As shown before, it is found that there is a range of a proper variable where these corrections differ little.
In this paper we study sneutrino dark matter in a recently proposed supersymmetric electroweak-scale inverse seesaw model, in which the majority of the sneutrino dark matter particle is a mixture of the right-handed sneutrino $\tilde{N}^c$ and the singlet field $\tilde{S}$. The scalar field $X$ responsible for the generation of neutrino masses can simultaneously play a crucial role for sneutrino annihilation in the early Universe via the pseudoscalar mediator $A_X$ into neutrinos. We focus here on the dominant annihilation channels and provide all the formulas together with analytic estimates …
We present a calculation of the two-loop quark-squark-gluino contributions to pseudoscalar Higgs boson production via gluon fusion in the MSSM. We regularize the loop integrals using the Pauli-Villars method, and obtain explicit and compact analytic results based on an expansion in the heavy particle masses. Our results - valid when the pseudoscalar Higgs boson is lighter than squarks and gluinos - can be easily implemented in computer codes for an efficient and accurate determination of the pseudoscalar production cross section.
Models of electroweak symmetry breaking with more than a single doublet of Higgs scalars contain a neutral pseudoscalar boson. The production of such a pseudoscalar in hadron collisions proceeds primarily via gluon fusion through a top-quark loop (except for those models in which the pseudoscalar coupling to bottom quarks is strongly enhanced). We compute the QCD corrections to this process in the heavy-quark limit, using an effective Lagrangian derived from the axial anomaly.
We investigate the pseudoscalar neutral Higgs-boson A^0 production in the polarized (gamma e) collisions with two different center of mass energies sqrt{s} = 500 GeV and sqrt{s} = 1 TeV. The cross-section of the process (gamma e -> e A^0) and the polarization asymmetry due the spin of the initial beams are calculated.
We complete the perturbative next-to-leading order corrections to the hard scattering amplitudes of deeply virtual meson leptoproduction processes at leading twist-two level by presenting the results for the production of flavor singlet pseudoscalar mesons. The new results are given in the common momentum fraction representation and in terms of conformal moments. We also comment on the flavor singlet results for deeply virtual vector meson production.
We generalize the Schwinger mechanism and calculate the probability of the decay of intense electromagnetic fields to pseudoscalar particles. We also point out that our estimate for axion emission in a previous paper was incorrect.
Production and decay rates, polarization and differential distributions of decay products are calculated for a heavy neutrino produced in charged pseudoscalar meson decay and decaying itself in charged pseudoscalar and lepton or a lepton-antilepton pair of different flavours and a light SM like (anti)neutrino.
An excess in gamma-rays emanating from the galactic centre has recently been observed in the Fermi-LAT data. This signal can be interpreted as resulting from WIMP annihilation, with the spectrum well-fit by dark matter annihilating dominantly into either bottom-quark or Higgs pairs. Supersymmetric models provide a well-motivated framework to study the implications of this signal in these channels. With a neutralino dark matter candidate, the gamma-ray excess cannot be easily accommodated in the minimal supersymmetric model, which in any case requires tuning below the percent level to explain t…
In this paper we present an analysis of the multiple hadron production induced by primary heavy quarks in e+e- annihilation with the account of most complete and corrected experimental data. In the framework of perturbative QCD, new theoretical bounds on the asymptotically constant differences of the multiplicities in processes with light and heavy quarks are given.
We study the decay $B^\pm\to ϕK^{\ast\pm}$, followed by the decay of the outgoing vector mesons into two pseudoscalars. The analysis of angular distributions of the decay products is shown to provide useful information about the annihilation contributions and possible tests of factorization.
We calculate the rate for pair production of light pseudoscalars by strong inhomogeneous and static electric (magnetic) fields. We show that, in the case of axions, the stability of atoms over cosmic lifetimes is jeopardised unless the Peccei-Quinn symmetry breaking scale $f_a$ is larger than ${\cal O} (10^{10} GeV)$.
We study the production of a mixed scalar-pseudoscalar Higgs boson in gluon fusion at the LHC, through next-to-next-to-leading order (NNLO) in QCD. We obtain fully differential results, including the decay of the Higgs boson to two charged lepton pairs. We discuss the impact of the interference between the scalar and pseudoscalar states. We also show differential distributions for several kinematic variables whose shape is sensitive to the parity of the Higgs boson, and assess the impact of the NNLO QCD corrections on these shapes.
The pseudoscalar quarkonium state, eta_4 1^S_0, formed by the Standard Model (SM) fourth generation quarks, is the best candidate among the fourth generation quarkonia to be produced at the LHC and VLHC. The production of this J^{PC} = 0^{-+} resonance is discussed and the background processes are studied to obtain the integrated luminosity limits for the discovery, depending on its mass.
We compute the complete next-to-leading order (NLO) SUSY-QCD corrections for the associated production of a pseudoscalar Higgs boson with a bottom quark via bottom-gluon fusion at the CERN Large Hadron Collider (LHC) and the Fermilab Tevatron. We find that the NLO QCD correction in the MSSM reaches $40%\sim50%$ at the LHC and $45%\sim80%$ at the Tevatron in our chosen parameter space.
We study the production of a pseudoscalar Higgs boson A^0 in association with a Z^0 boson at a future international linear collider (ILC). We consider the contributions to this process at the one loop level in the Minimal Supersymmetric Standard Model (MSSM) from top and bottom quarks as well as stop and sbottom squarks. We also study the squark contributions to the decay widths of the pseudoscalar Higgs boson for the decays A^0 --> γZ^0$ and A^0 --> Z^0 Z^0. The contribution from the supersymmetric loops are found to be directly proportional to the squark mixing and potentially large due to t…
We thoroughly investigate both transverse momentum and threshold resummation effects on scalar-pseudoscalar pair production via quark-antiquark annihilation at the $13~ \text{TeV}$ Large Hadron Collider at QCD NLO+NLL accuracy. A factorization method is introduced to properly supplement the soft-gluon (threshold) resummation contribution from parton distribution functions to the resummed results obtained by the Collins-Soper-Sterman resummation approach. We find that the impact of the threshold-resummation improved PDFs is comparable to the resummation effect of the partonic matrix element and…
In the next-to-minimal supersymmetric standard model (NMSSM), the unique $λS H_u H_d$ in the superpotential gives rise to a coupling involving the lighter pseudoscalar Higgs boson and a pair of charged or neutral Higgsinos, even in the limit of zero mixing between the two pseudoscalar Higgs bosons. We study the associated production of a very light pseudoscalar Higgs boson with a pair of charginos. The novel signature involves a pair of charged leptons from chargino decays and a pair of photons from the pseudoscalar Higgs boson decay, plus large missing energy at the LHC and ILC. The signal ma…
Exclusive pseudoscalar meson production in ep scattering at high energies is a direct probe for a possible "odderon" exchange in soft hadronic processes. Using a simple phenomenological ansatz for the odderon, we demonstrate how it can be separated from the contribution due to photon-photon fusion, and the relevant parameters be measured. Total cross sections and differential distributions are presented for pi0, eta, eta', and eta_c production. Results are given from both a full calculation and one using the equivalent photon approximation. The accuracy of the latter is discussed.
We present threshold enhanced N$^3$LO QCD corrections to inclusive Higgs production through bottom anti-bottom annihilation at hadron colliders using threshold resummed cross section. The resummed cross section is obtained using factorization properties and Sudakov resummation of the inclusive cross section. We use the recent results on threshold N$^3$LO corrections in QCD for Drell-Yan production and three loop QCD corrections to Higgs form factor with bottom anti-bottom quark to achieve this task. This is the first step towards the evaluation of complete N$^3$LO result. We have numerically d…
Recent analytical and numerical results for the three-loop polarization function allow to present a phenomenological analysis of the cross section for massive quark production in electron positron annihilation to order $α_s^2$. Numerical predictions based on fixed order perturbation theory are presented for charm and bottom production above 5 and 11.5 GeV, respectively. The contribution from these energy regions to $α(M_Z^2)$, the running QED coupling constant at scale M_Z, are given. The dominant terms close to threshold, i.e. in an expansion for small quark velocity $β$, are presented.
An improved description of four-pion production in electron-positron annihilation and in tau lepton decays is presented. The model amplitude is fitted to recent data from BaBar which cover a wide energy range and which were obtained exploiting the radiative return. Predicting tau decay distributions from e+e- data and comparing these predictions with ALEPH and CLEO results, the validity of isospin symmetry is confirmed within the present experimental errors. A good description of two- and three-pion sub-distributions is obtained. Special emphasis is put on the predictions for omega pi (-> pi+p…
Exclusive production of the $π$ mesons in neutrino--photon interactions at low momentum transfer is studied within the standard model. The corresponding cross sections are calculated analytically. Potential astrophysical implications and the significance for testing the standard model are discussed. The presented formalism applies to other pseudoscalar mesons as well.
The production of the Standard Model (SM) Higgs boson (H) in association with a jet is compared with that of the lightest scalar Higgs boson (h^0) and the pseudoscalar Higgs boson (A^0) of the Minimal Supersymmetric Model (MSSM) at both the CERN Large Hadron Collider (LHC) and the Fermilab Tevatron. We include both top and bottom quark loops to lowest order in QCD and investigate the limits of zero quark mass and infinite quark mass.
We investigate the production of a pseudoscalar Higgs-boson $A^0$ using the reaction $e\,γ\rightarrow e\,A^0$ at an $e\bar{e}$ collider with center of mass energy of 500 GeV. Supersymmetric contributions are included and provide a substantial enhancement to the cross section for most values of the symmetry breaking parameters. We find that, despite the penalty incurred in converting one of the beams into a source of backscattered photons, the $e\, γ$ process is a promising channel for the detection of the $A^0$.
In the pole-dominance model for the two-body nonleptonic decays of charmed mesons $D \rightarrow PV$ and $D \rightarrow VV$, it is shown that the contributions of the intermediate pseudoscalar and the axial-vector meson poles cancel each other in the annihilation diagrams in the chiral limit. In the same limit, the annihilation diagrams for the $D \rightarrow PP$ decays vanish independently.
We compute the threshold-resummed cross section for pseudo-scalar MSSM Higgs boson production by gluon fusion at hadron colliders. The calculation is performed at next-to-next-to leading logarithmic accuracy. We present results for both the LHC and Tevatron Run II. We analyze the factorization and renormalization scale dependence of the results, finding that after performing the resummation the corresponding cross section can be computed with an accuracy better than 10%.
We consider single charged Higgs ($H^{\pm}$) and pseudoscalar Higgs ($A^0$) production in association with a gauge boson at $μ^+μ^-$ colliders. We find that the tree-level t-channel and s-channel contributions to $μ^+μ^-\to H^{\pm}W^{\mp}, A^0Z$ are enhanced for large values of $\tanβ$, allowing sizeable cross-sections whose analogies at $e^+e^-$ colliders would be very small. These processes provide attractive new ways of producing such particles at $μ^+μ^-$ colliders and are superior to the conventional methods in regions of parameter space.
We discuss consequences of the models of "tensorial pomeron" and "vectorial pomeron" for exclusive diffractive production of scalar and pseudoscalar mesons in proton-proton collisions. Diffractive production of $f_{0}(980)$, $f_{0}(1370)$, $f_{0}(1500)$, $η$, and $η'(958)$ mesons is discussed. Different pomeron-pomeron-meson tensorial coupling structures are possible in general. In most cases two lowest orbital angular momentum - spin couplings are necessary to describe experimental differential distributions. For $f_{0}(980)$ and $η$ production reggeon-pomeron, pomeron-reggeon, and reggeon-re…
We present the calculation of scalar and pseudoscalar Higgs production in association with a top-antitop pair to the next-to-leading order (NLO) accuracy in QCD, interfaced with parton showers according to the MC@NLO formalism. We apply our results to the cases of light and very light Higgs boson production at the LHC, giving results for total rates as well as for sample differential distributions, relevant to the Higgs, to the top quarks, and to their decay products. This work constitutes the first phenomenological application of aMC@NLO, a fully automated approach to complete event generatio…
We calculate the O(alpha_s^3 ln(alpha_s)) contributions to the heavy-quarkonium production and annihilation rates. Our result sheds new light on the structure of the high-order perturbative corrections and opens a new perspective for a high-precision theoretical analysis. We also determine the three-loop anomalous dimensions of the nonrelativistic vector and pseudoscalar currents.
Pseudoscalar contributions to Zh production at the LHC at 95 GeV and above
The Institute of Mathematical Sciences（数学科学研究所）；Homi Bhabha National Institute（霍米·巴巴国立研究所）；Department of Physics, National Taiwan University（台湾大学物理系）；Instituto Superior de Engenharia de Lisboa — ISEL（里斯本高等理工学院）；Centro de Física Teórica e Computacional, Faculdade de Ciências, Universidade de Lisboa（里斯本大学理学院理论与计算物理中心）；Instituto de Física Teórica UAM-CSIC（马德里自治大学-西班牙国家科学研究委员会理论物理研究所）
We study the associated production of the $A^0$ neutral CP--odd Higgs boson with a neutral gauge boson $Z$ as well as single production of $A^0$ via $e^+e^- \to ν_e {\barν}_e A^0$ at the one loop level in the Minimal Supersymmetric Standard Model (MSSM). We show that the MSSM cross--section may be enhanced by light SUSY particles. Then we study the production processes $e^+e^-\to H^0_iZ$, $H^0_iν_e\bar ν_e$ and $H^0_iH^0_j$ in the context of the MSSM with scalar-pseudoscalar mixing. In a given channel we show that the cross--section for all i (=1,2,3) can be above 0.1 fb provided $M_{H_{2,3}}\…
We consider exclusive $π^0$ production in ep-scattering. At high energies odderon and photon exchange contribute. The photon exchange contribution is evaluated exactly using data for the total virtual photon-proton absorption cross section. The odderon exchange contribution is calculated in nonperturbative QCD, using functional integral techniques and the model of the stochastic vacuum. For the proton we assume a quark-diquark structure as suggested by the small odderon amplitude in pp and $p \bar{p}$ forward scattering. We show that odderon exchange leads to a much larger inelastic than elast…
