Publications (18)7.37 Total impact
-
Article: Atmospheric Neutrino Mixing and b-s Transitions: Testing Lopsided SO(10) Flavor Structure in B physics
[show abstract] [hide abstract]
ABSTRACT: We point out that the correlation between the large atmospheric neutrino mixing and the $b \to s$ transition, if exists, comes from the lopsided flavor structure in SO(10) grand unification theory. We suggest testing the correlation by studying the deviation of $S_{\phi K_S}$ and $S_{\eta' K_S}$ from the standard model predictions along with the constraints from $\Delta M_{B_S}$ and $b\to s \gamma$ in a realistic SO(10) model with lopsided flavor structure. We find a specific correlation between $S_{\phi K_S}$ and $S_{\eta' K_S}$ that is intrinsic to the lopsided structure and discuss how to confirm or rule out this flavor pattern by the more accurate measurements of these CP violation quantities in B decay.01/2007; -
Article: Leptogenesis in Realistic SO(10) Models
[show abstract] [hide abstract]
ABSTRACT: We study the origin of baryonic matter via leptogenesis in realistic SO(10) models, in particular, in a new lopsided mass matrix model introduced recently by three of the authors. By introducing simple CP-violating phases in the mass matrix of the right-handed neutrinos, the model generates sufficient baryon asymmetry without fine-tuning. We compare this result with other realistic SO(10) models.06/2006; -
Article: An SO(10) GUT Model With Lopsided Mass Matrix and Neutrino Mixing Angle theta_13
[show abstract] [hide abstract]
ABSTRACT: An alternative supersymmetric SO(10) grand unification model with lopsided fermion mass matrices is introduced. It generates a large solar-neutrino-mixing angle through the neutrinos' Dirac mass matrix constrained by the SO(10) group structure, avoiding the fine-tuning required in the Majorana mass matrix of right-handed neutrinos. The model fits well the known data on masses and mixings of quarks and leptons, and predicts a sizable lepton mixing $\sin^22\theta_{13}\simeq 0.074$, which is significantly larger than that of the original lopsided model. Comment: 9 pages10/2005; -
Article: Fixing Two-Nucleon Weak-Axial Coupling L_{1,A} From mu-d Capture
[show abstract] [hide abstract]
ABSTRACT: We calculate the muon capture rate on the deuteron to next-to-next-to-leading order in the pionless effective field theory. The result can be used to constrain the two-nucleon isovector axial coupling L_{1,A} to +/- 2 fm^3 if the muon capture rate is measured to 2% level. From this, one can determine the neutrino-deuteron break up reactions and the pp-fusion cross section in the sun to a same level of accuracy. Comment: replaced by the version appearing in the PRC06/2005; -
Article: Deuteron Compton Scattering in Effective Field Theory: Spin-Dependent Cross Sections and Asymmetries
[show abstract] [hide abstract]
ABSTRACT: Polarized Compton scattering on the deuteron is studied in nuclear effective field theory. A set of tensor structures is introduced to define 12 independent Compton amplitudes. The scalar and vector amplitudes are calculated up to ${\cal O}((Q/\Lambda)^2)$ in low-energy power counting. Significant contribution to the vector amplitudes is found to come from the spin-orbit type of relativistic corrections. A double-helicity dependent cross section $\Delta_1 \sigma = (\sigma_{+1-1}-\sigma_{+1+1})/2$ is calculated to the same order, and the effect of the nucleon isoscalar spin-dependent polarizabilities is found to be smaller than the effect of isoscalar spin-independent ones. Contributions of spin-independent polarizabilities are investigated in various asymmetries, one of which has as large as 12 (26) percent effect at the center-of-mass photon energy 30 (50) MeV. Comment: 22 pages, 8 figures included, replaced with the version submitted to PRC08/2004; -
Article: Deuteron Compton Scattering in Effective Field Theory And Spin-Independent Nucleon Polarizabilities
[show abstract] [hide abstract]
ABSTRACT: Deuteron Compton scattering is calculated to $\mathcal{O}(Q^2)$ in pionless effective field theory using a dibaryon approach. The vector amplitude, which was not included in the previous pionless calculations, contributes to the cross section at $\mathcal{O}(Q^2)$ and influences significantly the extracted values of nucleon electric polarizability at incident photon energy 49 MeV. We recommend future high precision deuteron compton scattering experiments being performed at 25-35 MeV photon energy where the nucleon polarizability effects are appreciable and the pionless effective field theory is most reliable. For example, a measurement at 30 MeV with a 3% error will constrain the isoscalar nucleon electric polarizability $% \alpha_{0}$ with a $\sim 30%$ error. Comment: 11 pages, 5 figures included07/2004; -
Article: Leading chiral contributions to the spin structure of the proton.
[show abstract] [hide abstract]
ABSTRACT: The leading chiral contributions to the quark and gluon components of the proton spin are calculated using heavy-baryon chiral perturbation theory. Similar calculations are done for the moments of the generalized parton distributions relevant to the quark and gluon angular momentum densities. These results provide useful insight into the role of pions in the spin structure of the nucleon and can serve as a guide for extrapolating lattice QCD calculations at large quark masses to the chiral limit.Physical Review Letters 03/2002; 88(5):052003. · 7.37 Impact Factor -
Article: Constructing Parton Convolution in Effective Field Theory
[show abstract] [hide abstract]
ABSTRACT: Parton convolution models have been used extensively in describing the sea quarks in the nucleon and explaining quark distributions in nuclei (the EMC effect). From effective field theory point of view, we construct the parton convolution formalism which has been the underlying conception of all convolution models. We explain the significance of scheme and scale dependence of the auxiliary quantities such as the pion distributions in a nucleon. As an application, we calculate the complete leading nonanalytic chiral contribution to the isovector component of the nucleon sea. Comment: 4 pages, revtex, no figure07/2001; -
Article: Is the Sullivan process compatible with QCD chiral dynamics?
[show abstract] [hide abstract]
ABSTRACT: We calculate the leading non-analytic quark-mass dependence in the moments of isovector quark distributions using heavy-baryon chiral perturbation theory. The results differ from what has been obtained from the Sullivan process in which hard scattering occurs through the virtual pion cloud of the nucleon. Our results provide useful guidance in formulating meson-cloud models consistent with chiral dynamics and can be used to constrain the extrapolations of the existing lattice QCD results to the physical quark massesPhysics Letters B. 06/2001; -
Article: Comment on "Subleading Corrections to Parity Violating Pion Photoproduction"
[show abstract] [hide abstract]
ABSTRACT: In a recent preprint, hep-ph/0012253, Zhu et al. calculated a part of the next-to-leading order corrections to parity-violating pion photoproduction (pol)gamma p-> pi^+ n in heavy-baryon chiral perturbation theory. They claim they have found the contribution as large as the leading-order. If correct, the process will not be a clean way to extract the longest range PV pion-nucleon coupling constant h_{\pi NN}^(1), as was asserted in our previous publications (hep-ph/0011230, nucl-th/0011100). In this comment we show that there is no solid evidence to support Zhu et al.'s claim. Moreover, we show that the subleading parity-violating coupling h_V cannot be extracted from observables at the order of interest based on the formalism of effective field theory.02/2001; -
Article: Parity-Violating Pion-Nucleon Coupling h_{\pi NN}^{(1)} from \pi^+ Electroproton Production Near the Threshold
[show abstract] [hide abstract]
ABSTRACT: We study the possibility of measuring parity-violating pion-nucleon coupling h_{\pi NN}^{(1)} from \pi^+ electroproton production in the threshold region. We calculate the electron-helicity asymmetry in terms of h_{\pi NN}^{(1)} and the Z-boson exchange between the electron and proton in leading-order heavy-baryon chiral perturbation theory. From the result, we demonstrate that the coupling can be determined to an accuracy of about 2 10^{-7} in an experiment with incident electron energy 250 MeV, luminosity 10^{38} sec^{-1} cm^{-2}, and a running time of 10^7 sec. Comment: 9 pages and 6 figures11/2000; -
Article: Measuring the P-odd Pion-Nucleon Coupling h_{\pi NN}^{(1)} in \pi^+ Photoproton Production Near the Threshold
[show abstract] [hide abstract]
ABSTRACT: We show that polarized gamma p -> \pi^+ n in the threshold region is an excellent candidate for measuring the leading parity-violating pion-nucleon coupling h_{\pi NN}^{(1)} to an uncertainty of 20% if it has a natural size from dimensional analysis. The conclusion is based on a large unpolarized cross section, a new low-energy theorem for the photon polarization asymmetry at the threshold A_\gamma|_{th} = \sqrt{2} f_\pi (\mu_p-\mu_n) h_{\pi NN}^{(1)}/g_A m_N \sim h_{\pi NN}^{(1)}/2, and its strong dominance at forward and backward angles in the threshold region. Comment: 4 pages, 3 figures. More data points in fig. 1 and note added in proof added11/2000; -
Article: Drell–Hearn–Gerasimov sum-rule for the deuteron in nuclear effective field theory
[show abstract] [hide abstract]
ABSTRACT: The Drell–Hearn–Gerasimov sum rule for the deuteron is studied in nuclear effective field theory. The low-energy theorem for the spin-dependent Compton amplitude f1(ω) is derived to the next-to-leading order in low-energy expansion. The spin-dependent photo-disintegration cross-section σP−σA is calculated to the same order, and its contribution to the dispersive integral is evaluated.Physics Letters B. -
Article: An SO(10) GUT model with lopsided mass matrix and neutrino mixing angle θ13
[show abstract] [hide abstract]
ABSTRACT: An alternative supersymmetric SO(10) grand unification model with lopsided fermion mass matrices is introduced. It generates a large solar-neutrino mixing angle through the neutrinos' Dirac mass matrix constrained by the SO(10) group structure, avoiding the fine-tuning required in the Majorana mass matrix of right-handed neutrinos. The model fits well the known data on masses and mixings of quarks and leptons, and predicts a sizable lepton mixing sin22θ13≃0.074, which is significantly larger than that of the original lopsided model.Physics Letters B. -
Article: Leptogenesis in realistic SO(10) models
[show abstract] [hide abstract]
ABSTRACT: We study the origin of baryonic matter via leptogenesis in realistic SO(10) models, in particular, in a new lopsided mass matrix model introduced recently by three of the authors. It is shown that the model generates sufficient baryon asymmetry in addition to fitting to fermion masses and mixing. We compare this result with other realistic SO(10) models.Physics Letters B. -
Article: Parity-violating pion–nucleon coupling hπNN(1) from π+-electroproton production near the threshold
[show abstract] [hide abstract]
ABSTRACT: We study the possibility of measuring parity-violating pion–nucleon coupling hπNN(1) from π+-electroproton production in the threshold region. We calculate the electron-helicity asymmetry in terms of hπNN(1) and the Z-boson exchange between the electron and proton in leading-order heavy-baryon chiral perturbation theory. From the result, we demonstrate that the coupling can be determined to an accuracy of ∼2×10−7 in an experiment with incident electron energy 250 MeV, luminosity 1038 s−1 cm−2, and a running time of 107 s.Physics Letters B. -
Article: Sum rules and spin-dependent polarizabilities of the deuteron in effective field theory
[show abstract] [hide abstract]
ABSTRACT: We construct sum rules for the forward vector and tensor polarizabilities for any spin-S target and apply them to the spin-1 deuteron. We calculate these polarizabilities of the deuteron to the next-to-leading order in the pionless effective field theory.Physics Letters B. -
Article: Large-Nc quark distributions in the delta and chiral logarithms in quark distributions of the nucleon
[show abstract] [hide abstract]
ABSTRACT: In a world with two quark flavors and a large number of colors (Nc), the polarized and unpolarized quark distributions in the delta are completely determined by those in the nucleon up to relative . In particular, we find and , where q=u,d and Tz the charge state of a delta. The result can be used to estimate the leading chiral-logarithmic corrections to the quark distributions in the nucleon.Physics Letters B.
Top co-authors
Top Journals
Institutions
-
2001–2007
-
University of Maryland, College Park
- Department of Physics
College Park, MD, USA
-
-
2005
-
National Taiwan University
- Department of Physics
Taipei, Taipei, Taiwan
-
