arXiv subjects

Bo-Qiang Ma

Publications and source records attributed to Bo-Qiang Ma.

At least 235 records · Page 13Linked to original sources

arXiv2006

Effect due to charge symmetry violation on the Paschos-Wolfenstein relation

The modification of the Paschos-Wolfenstein relation is investigated when the charge symmetry violations of valence and sea quark distributions in the nucleon are taken into account. We also study qualitatively the impact of charge symmetry violation (CSV) effect on the extraction of $\sin^{2}θ_{w}$ from deep inelastic neutrino- and antineutrino-nuclei scattering within the light-cone meson-baryon fluctuation model. We find that the effect of CSV is too small to give a sizable contribution to the NuTeV result with various choices of mass difference inputs, which is consistence with the prediction that the strange-antistrange asymmetry can account for largely the NuTeV deviation in this model. It is noticeable that the effect of CSV might contribute to the NuTeV deviation when the larger difference between the internal momentum scales, $α_{p}$ of the proton and $α_{n}$ of the neutron, is considered.

hep-ph↗

arXiv2006

Energy scale independence of Koide's relation for quark and lepton masses

Koide's mass relation of charged leptons has been extended to quarks and neutrinos, and we prove here that this relation is independent of energy scale in a huge energy range from $1 {GeV}$ to $2\times10^{16} {GeV}$. By using the parameters $k_u$, $k_d$ and $k_ν$ to describe the deviations of quarks and neutrinos from the exact Koide's relation, we also check the quark-lepton complementarity of masses such as $k_{l}+k_{d} \approx k_ν+k_{u} \approx 2$, and show that it is also independent (or insensitive) of energy scale.

hep-ph↗

arXiv2005

On the cos 2 phi asymmetry in unpolarized leptoproduction

We investigate the origin of the cos 2 phi azimuthal asymmetry in unpolarized semiinclusive DIS. The contributions to this asymmetry arising from the intrinsic transverse motion of quarks are explicitly evaluated, and predictions for the HERMES and COMPASS kinematic regimes are presented. We show that the effect of the leading-twist Boer-Mulders function h_1^perp(x, k_T^2), which describes a correlation between the transverse momentum and the transverse spin of quarks, is quite significant and may also account for a part of the cos 2 phi asymmetry measured by ZEUS in the perturbative domain.

hep-ph↗

arXiv2005

NuTeV Anomaly Versus Strange-Antistrange Asymmetry

We report the correction from the asymmetric strange-antistrange sea of the nucleon by using both the light-cone baryon-meson fluctuation model and the chiral quark model, and show that a significant part of the NuTeV anomaly can be explained by the strange-antistrange asymmetry. We also show that the calculated $s/\bar{s}$ asymmetry are compatible with the NuTeV data by including some additional symmetric $s/\bar{s}$ quark contribution.

hep-ph↗

arXiv2005

Neutrons and antiprotons in ultrahigh energy cosmic rays

The neutron fraction in the very high energy cosmic rays near the Greisen-Zatsepin-Kuzmin (GZK) cutoff energy is analyzed by taking into account the time dilation effect of the neutron decays and also the pion photoproduction behaviors above the GZK cutoff. We predict a non-trivial neutron fraction above the GZK cutoff and a negligibly small neutron fraction below. However, there should be a large antiproton fraction in the high energy cosmic rays below the GZK cutoff in several existing models for the observed cosmic-ray events above and near the GZK cutoff. Such a large antiproton fraction can manifest itself by the muon charge ratio $μ^+/μ^-$ in the collisions of the primary nucleon cosmic rays with the atmosphere, if there is no neutron contribution. We suggest to use the muon charge ratio as one of the information to detect the composition of the primary cosmic rays near or below the GZK cutoff.

astro-ph↗

arXiv2005

Baryonium with a phenomenological skyrmion-type potential

In this paper, we investigate the nucleon-antinucleon static energies in the Skyrme model with the product {\it Anzatz}. The calculation shows that in the ungroomed $S\bar S$ (skyrmion and antiskyrmion) channel, which leads to rapid annihilation, there exists a quasi-stable bound state which may give a natural explanation for the near-threshold enhancement in the proton-antiproton $(p\bar{p})$ mass spectrum reported by the BES Collaboration and the Belle Collaboration. Similar to the phenomenological well potential of the deuteron, we construct a phenomenological skyrmion-type potential to study this narrow $p\bar{p}$-resonance in $ J/ψ\to γp\bar{p}$. By this potential model, a $p\bar{p}$ baryonium with small binding energies is suggested and the decay width of this state is calculated by WKB approximation. In this picture the decay is attributed to quantum tunnelling and $p\bar{p}$ annihilation. Prediction on the decay mode from the baryonium annihilation at rest is also pointed out.

hep-ph↗

arXiv2005

Probing nucleon strange asymmetry from charm production in neutrino deep inelastic scattering

We propose a means to detect the nucleon strange quark-antiquark asymmetry, which is predicted as a non-perturbative effect, but still unchecked directly by available experiments. The difference for the $D(c\bar{q})$ and $\bar{D}(\bar{c}q)$ meson production cross sections in neutrino and antineutrino induced charged current deep inelastic scattering is illustrated to be sensitive to the nucleon strange asymmetry. Prospect is given and the effect due to the light quark fragmentation is also discussed for the extraction of the strange asymmetry in future experiments.

hep-ph↗

arXiv2005

Parity-violating asymmetry of $W$ bosons produced in $p$-$p$ collisions

The parity-violating asymmetry is an ideal tool to study the quark helicity distribution in the proton. We study the parity-violating asymmetry of $W^{\pm}$ bosons produced by longitudinally polarized $p$-$p$ collision in RHIC, based on predictions of quark distributions of the proton in the SU(6) quark-spectator-diquark model and a perturbative QCD based counting rule analysis. We find that the two models give nearly equal asymmetry for $W^+$ but that for $W^-$ quite different. Therefore future experiments on such quantity can help to clarify different predictions of the value $Δd(x)/d(x)$ at $x \to 1$ in the proton.

hep-ph↗

arXiv2005

Nucleon sea in the effective chiral quark model

The asymmetries of both light-flavor antiquark $\bar{d}(x)-\bar{u}(x)$ and strange-antistrange $s(x)-\bar{s}(x)$ distributions of the nucleon sea are considered with more details in the effective chiral quark model. We find that the asymmetric distribution of light-flavor antiquarks $\bar{d}(x)-\bar{u}(x)$ matches the experiment data well and that the asymmetry of strange and antistrange distributions can bring about 60-100% correction to the NuTeV anomaly of $\sin^{2}θ_{w}$, which are three standard deviations from the world average value measured in other electroweak processes. The results on the correction to the NuTeV anomaly are insensitive to the inputs of the constituent quark distributions and the cut-off parameters. The ratios of $\bar{d}(x)/\bar{u}(x)$ and $s(x)/\bar{s}(x)$ are also discussed, and it is found that the ratio $s(x)/\bar{s}(x)$ is compatible with the available experiments with an additional symmetric sea contribution being considered effectively.

hep-ph↗

arXiv2005

Relations between quark and lepton mixing angles and matrices

We discuss the relations between the mixing angles and the mixing matrices of quarks and leptons. With Raidal's numerical relations, we parametrize the lepton mixing (PMNS) matrix with the parameters of the quark mixing (CKM) matrix, and calculate the products of $V_{\mathrm{CKM}}U_{\mathrm{PMNS}}$ and $U_{\mathrm{PMNS}}V_{\mathrm{CKM}}$. Also, under the conjectures $V_{\mathrm{CKM}}U_{\mathrm{PMNS}}=U_{\mathrm{bimax}}$ or $U_{\mathrm{PMNS}}V_{\mathrm{CKM}}=U_{\mathrm{bimax}}$, we get the PMNS matrix naturally, and test Raidal's relations in these two different versions. The similarities and the differences between the different versions are discussed in detail.

hep-ph↗

arXiv2005

Estimate of neutrino masses from Koide's relation

We apply Koide's mass relation of charged leptons to neutrinos and quarks, with both the normal and inverted mass schemes of neutrinos discussed. We introduce the parameters $k_ν$, $k_u$ and $k_d$ to describe the deviations of neutrinos and quarks from Koide's relation, and suggest a quark-lepton complementarity of masses such as $ k_{l}+k_{d} \approx k_ν+k_{u} \approx 2$. The masses of neutrinos are determined from the improved relation, and they are strongly hierarchical (with the different orders of magnitude of $10^{-5} eV$, $10^{-3} eV$, and $10^{-2} eV$).

hep-ph↗

arXiv2005

Unified Parametrization of Quark and Lepton Mixing Matrices

We present a unified parametrization of quark and lepton mixing matrices. By using some simple relations between the mixing angles of quarks and leptons, i.e., the quark-lepton complementarity, we parametrize the lepton mixing matrix with the Wolfenstein parameters $λ$ and $A$ of the quark mixing matrix. It is shown that the Wolfenstein parameter $λ$ can measure both the deviation of the quark mixing matrix from the unit matrix, and the deviation of the lepton mixing matrix from the exactly bimaximal mixing pattern.

hep-ph↗

arXiv2005

Azimuthal asymmetry in unpolarized $πN$ Drell-Yan process

Taking into account the effect of final state interaction, we calculate the non-zero (naïve) $T$-odd transverse momentum dependent distribution $h_1^{\perp}(x,\kp^2)$ of the pion in a quark-spectator-antiquark model with effective pion-quark-antiquark coupling as a dipole form factor. Using the model result we estimate the $\cos 2ϕ$ asymmetries in the unpolarized $π^- N$ Drell-Yan process which can be expressed as $h_1^{\perp}\times\bar{h}_1^{\perp}$. We find that the resulting $h_{1π}^\p(x,\kp^2)$ has the advantage to reproduce the asymmetry that agrees with the experimental data measured by NA10 Collaboration. We estimate the $\cos2ϕ$ asymmetries averaged over the kinematics of NA10 experiments for 140, 194 and 286 GeV $π^-$ beam and compare them with relevant experimental data.

hep-ph↗

arXiv2005

Collins Effect in Single Spin Asymmetries of the $p^{\uparrow}p \to πX$ Process

We investigate the Collins effect in single spin asymmetries (SSAs) of the $p^{\uparrow}p \to πX$ process, by taking into account the transverse momentum dependence of the microscopic sub-processes cross sections, with the transverse momentum in the Collins function integrated over. We find that the asymmetries due to the Collins effect can only explain the available data at best qualitatively, by using our choices of quark distributions in the quark-diquark model and a pQCD-based analysis, together with several options of the Collins function. Our results indicate the necessity to take into account contributions from other effects such as the Sivers effect or twist-3 contributions.

hep-ph↗

arXiv2005

Detection of cosmic neutrino clustering by cosmic ray spectra

We propose a method to investigate the scenario that cosmic relic neutrinos are highly clustered around stars and galaxies, or dark-matter clusters, rather than uniformly distributed in the universe. Such a scenario can be detected or constrained by the interaction of high energy cosmic ray protons and nuclei with the cosmic neutrinos. There should be observable signature in the energy spectra of cosmic ray protons and nuclei for a neutrino clustering factor beyond $10^{13}$. We provide a relation on the signature onset positions between proton and nuclei spectra, and discuss possible support from existing experiments. It is also suggested that the relative abundance of cosmic ray nuclei may detect or constrain the cosmic neutrinos with smaller clustering.

astro-ph↗

arXiv2005

NuTeV Anomaly & Strange-Antistrange Asymmetry

The NuTeV Collaboration reported a value of $\sin^{2}θ_{w}$ measured in neutrino-nucleon deep inelastic scattering, and found that the value is three standard deviations from the world average value of other electroweak measurements. If this result cannot be explained within conventional physics, it must imply some novel physics beyond the standard model. We report the correction from the asymmetric strange-antistrange sea by using both the light-cone baryon-meson fluctuation model and the chiral quark model, and show that a significant part of the NuTeV anomaly can be explained by the strange-antistrange asymmetry.

hep-ph↗

arXiv2005

Photon-meson transition form factors of light pseudoscalar mesons

The photon-meson transition form factors of light pseudoscalar mesons $π^{0}$, $η$, and $η^{\prime}$ are systematically calculated in a light-cone framework, which is applicable as a light-cone quark model at low $Q^{2}$ and is also physically in accordance with the light-cone pQCD approach at large $Q^{2}$. The calculated results agree with the available experimental data at high energy scale. We also predict the low $Q^{2}$ behaviors of the photon-meson transition form factors of $π^{0}$, $η$ and $η^{\prime }$, which are measurable in $e+A({Nucleus})\to e+A+M$ process via Primakoff effect at JLab and DESY.

hep-ph↗

arXiv2004

Effect of Asymmetric Strange-Antistrange Sea to the NuTeV Anomaly

We calculate the strange quark and antiquark distributions of the nucleon by using the effective chiral quark model, and find that the strange-antistrange asymmetry can bring a contribution of about 60--100% to the NuTeV deviation of $\sin^{2}θ_{w}$ from the standard value measured in other electroweak processes. The results are insensitive to different inputs. The light-flavor quark asymmetry of $\bar{d}-\bar{u}$ is also investigated and found to be consistent with the experimental measurements. Therefore the chiral quark model provides a successful picture to understand the NuTeV anomaly, as well as the light-flavor quark asymmetry and the proton spin problem in previous studies.

hep-ph↗