18316695
Analysis of Lambda(b) ---> Lambda(c) weak decays in heavy quark effective theory
The Lambda_b to Lambda_c semileptonic decay is analyzed in the framework of heavy quark effective theory to the order of 1/m_c and 1/m_b. The QCD sum rule and large N_c predictions to the decay form factors are applied. It argues that the subleading baryonic Isgur-Wise function in the large N_c limit vanishes. The decay rates, distributions and asymmetry parameters are calculated numerically. Some of the nonleptonic decay modes are discussed in the end.
119384069
Supersymmetry for Fermion Masses
It is proposed that supersymmetry (SUSY) maybe used to understand fermion mass hierarchies. A family symmetry Z_{3L} is introduced, which is the cyclic symmetry among the three generation SU(2) doublets. SUSY breaks at a high energy scale ~ 10^{11} GeV. The electroweak energy scale ~ 100 GeV is unnaturally small. No additional global symmetry, like the R-parity, is imposed. The Yukawa couplings and R-parity violating couplings all take their natural values which are about (10^0-10^{-2}). Under the family symmetry, only the third generation charged fermions get their masses. This family symmetry is broken in the soft SUSY breaking terms which result in a hierarchical pattern of the fermion masses. It turns out that for the charged leptons, the tau mass is from the Higgs vacuum expectation value (VEV) and the sneutrino VEVs, the muon mass is due to the sneutrino VEVs, and the electron gains its mass due to both Z_{3L} and SUSY breaking. The large neutrino mixing are produced with neutralinos playing the partial role of right-handed neutrinos. |V_{e3}| which is for nu_e-nu_{tau} mixing is expected to be about 0.1. For the quarks, the third generation masses are from the Higgs VEVs, the second generation masses are from quantum corrections, and the down quark mass due to the sneutrino VEVs. It explains m_c/m_s, m_s/m_e, m_d>m_u and so on. Other aspects of the model are discussed.
119216988
LHCb $\bigtriangleup A_{CP}$ of $D$ Meson and R-Parity Violation
LHCb collaboration has recently announced a measurement of the difference of time-integrated CP asymmetries between $D\rightarrow K^+K^-$ and $D \rightarrow \pi^+\pi^-$. This result provides the evidence of large direct CP violation in $D$ meson and reveals some important implications on underlying new physics. It is shown that the direct CP violation in $D$ meson can be enhanced by R-parity violating supersymmetry, while CP violations in $K$ and $B$ mesons are suppressed by this new physics, which is in consistence with previous experiments. Constraints on the model parameters and some consequences are also discussed.
118790054
Phenomenological aspects of R-parity violating supersymmetry with a vectorlike extra generation
Phenomenological analysis to the R-parity violating supersymmetry with a vectorlike extra generation is performed in detail. It is found that, via the trilinear couplings, the correct neutrino spectrum can be obtained. The Higgs mass rises to 125 GeV by new up-type Yukawa couplings of vectorlike quarks with no need of very heavy superpartners. Phenomena of new heavy fermions at LHC are predicted. DOI: 10.1103/PhysRevD.87.075012
117463737
A Supersymmetric model with the gauge symmetry SU(3)(1) x SU(2)(1) x U(1)(1) x SU(3)(2) x SU(2)(2) x U(1)(2)
A supersymmetric model with two copies of the Standard Model gauge groups is constructed in the gauge mediated supersymmetry breaking scenario. The supersymmetry breaking messengers axe in a simple form. The Standard Model is obtained after first step gauge symmetry breaking. In the case of one copy of the gauge interactions being strong, a scenario of electroweak symmetry breaking is discussed, and the gauginos are generally predicted to be heavier than the sfermions.
14586429
QCD sum rule analysis for the Lambda(b)->Lambda(c) semileptonic decay
Abstract The 1 m c and 1 m b corrections to the Λ b → Λ c semileptonic decay are analyzed by QCD sum rules. Within the framework of heavy quark effective theory, the subleading baryonic Isgur-Wise function of Λ b → Λ c has been calculated. It is shown that the corrections due to the 1 m Lagrangian insertion are negligibly small. The sizable 1 m Q effect to the decay lies only in the weak current. The decay spectrum and the branching ratio are given.
119236514
Scalar Glueball in Radiative J/psi Decay on the Lattice
The form factors in the radiative decay of J/psi to a scalar glueball are studied within quenched lattice QCD on anisotropic lattices. The continuum extrapolation is carried out by using two different lattice spacings. With the results of these form factors, the partial width of J/psi radiatively decaying into the pure gauge scalar glueball is predicted to be 0.35(8) keV, which corresponds to a branching ratio of 3.8(9) x 10(-3). By comparing with experiments, out results indicate that f(0)(1710) has a larger overlap with the pure gauge glueball than other related scalar mesons. DOI: 10.1103/PhysRevLett.110.021601
118968482
Massive overlap fermions on anisotropic lattices
We formulate the massive overlap fermions on anisotropic lattices. We find that the dispersion relation for the overlap fermion resembles the continuum form in the low-momentum region once the bare parameters are properly tuned. The quark self-energy and the quark field renormalization constants are calculated to one-loop in bare lattice perturbation theory. Using tadpole improved perturbation theory, we establish the relation between the well-tuned parameters and the quark mass once the bare coupling is given. We argue that massive domain wall quarks might be helpful in lattice QCD studies on heavy-light hadron spectroscopy.
118538966
Review of D Semi-leptonic Decays
Semi-leptonic D decays continue to play an important role in the field of flavor physics. During this presentation, recent measurements from pseudo-scalar to pseudo-scalar modes, pseudo-scalar to vector modes, and rare modes will be discussed. These results are important for many purposes, such as validating the machinery of lattice QCD, extracting CKM matrix elements, and searching for new physics and new interactions.
121293716
Symmetry Breaking in Finite Volume
Spontaneous symmetry breaking is a cooperative phenomenon for systems with infinitely many degrees of freedom and it plays an essential role in quantum field theories. Lattice O(N) model is studied within the Hamiltonian approach using an adiabatic approximation. It is shown that the low-lying spectrum of the system in the broken phase can be understood by using the adiabatic, or Born-Oppenheimer approximation, which turns out to become an expansion in the inverse power of volume. In the infinite volume limit, the symmetry is broken while in the finite volume the slow rotation of the zero-momentum mode restores the symmetry and gives rise to the rotator spectrum, which has been observed in realistic Monte Carlo simulations.
14759412
I=2 PION SCATTERING LENGTH WITH IMPROVED ACTIONS ON ANISOTROPIC LATTICES
ππ scattering length in the I=2 channel is calculated within quenched approximation using improved gauge and improved Wilson fermion actions on anisotropic lattices. The results are extrapolated towards the chiral, infinite volume and continuum limit. This result improves our previous result on the scattering length. In the chiral, infinite volume and continuum limit, we obtain , which is consistent with the result from Chiral Perturbation Theory, the experiment and results from other lattice calculations.