Jong-Phil Lee

Observation of Spin-Dependent Charge Symmetry Breaking in

The energy spacing between the spin-doublet bound state of _{Λ}^{4}He(1^{+},0^{+}) was determined to be 1406±2±2u2009u2009keV, by measuring γ rays for the 1^{+}→0^{+} transition with a high efficiency germanium detector array in coincidence with the ^{4}He(K^{-},π^{-})_{Λ}^{4}He reaction at J-PARC. In comparison to the corresponding energy spacing in the mirror hypernucleus _{Λ}^{4}H, the present result clearly indicates the existence of charge symmetry breaking (CSB) in ΛN interaction. By combining the energy spacings with the known ground-state binding energies, it is also found that the CSB effect is large in the 0^{+} ground state but is vanishingly small in the 1^{+} excited state, demonstrating that the ΛN CSB interaction has spin dependence.

\Lambda N

We have carried out an experiment to search for a neutron-ric h hypernucleus, 6 Λ H, by the6Li(π−,K+) reaction atpπ− =1.2 GeV/c. The obtained missing-mass spectrum with an estimated energy re solution of 3.2 MeV (FWHM) showed no peak structure correspo nding to the6 Λ H hypernucleus neither below nor above the 4 Λ H+2n particle decay threshold. An upper limit of the production c ross section for the bound6 Λ H hypernucleus was estimated to be 1.2 nb /sr at 90% confidence level.

Interaction: Gamma-Ray Spectroscopy of

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.

^4_{\Lambda }

The leading Isgur-Wise form factor xi (y) parametrizing the semileptonic transitions Lambda (b) --> Lambda (1/2)(cl)l and Lambdab --> Lambda (3/2)(cl)l is calculated by using the QCD sum rules in the framework of heavy quark effective theory, where Lambda (1/2)(cl) and Lambda (3/2)(cl) is the orbitaIly excited charmed baryon doublet with J(P) = (1(-)/2, 3(-)/2). The interpolating currents with transverse covariant derivative are adopted for Lambda (1/2)(cl) and Lambda (3/2)(cl) in the analysis. The slope parameter rho (2) in linear approximation of the Isgur-Wise function is obtained to be rho (2) = 2.01, and the interception to be xi (1) = 0.29. The decay branching ratios are estimated

He

Abstract The mass parameter of orbitally excited Λ c baryons is calculated by using QCD sum rule in the framework of heavy quark effective theory. Two kinds of interpolating current for the excited heavy baryons are introduced. It is obtained that Λ =1.08 +0.095 −0.104 GeV for the non-derivative current and Λ =1.06 +0.090 −0.107 GeV for the current with derivative. These results are consistent with experimental data.

Search for HΛ6 hypernucleus by the Li6(π−,K+) reaction at pπ−=1.2GeV/c

The mass spectrum of the L = 1 orbitally excited heavy baryons with light quarks in the spin-flavor symmetric representation is studied by the 1/N-c expansion method in the framework of heavy quark effective theory. The mixing effect from the baryons in the mixed representation is considered. The general pattern of the spectrum is predicted which will be verified by experiments in the near future. The 1/m(Q) and SU(3) corrections are also considered. Mass relations for the baryons Lambda (()(cl)*()), Sigma (()(cl)*()), Xi (()(cl)()()*()), and delta (()(cl)*()) are derived.

Analysis of Λ b → Λ 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.

Leading Isgur–Wise form factor of Λb→Λc1 transition using QCD sum rules

L=1 excited heavy baryon masses are analyzed by heavy quark and large N_c expansions. In heavy quark limit, mass is parameterized by Lambda-bar and it is expanded further by spin-flavor breaking operators to the zeroth order of 1/N_c. Expanding coefficients will be fixed by more data on the excited baryons in the near future.

QCD sum rule analysis of excited Lambda(c) mass parameter

The decay of

1/m(Q) and 1/N-c expansions for excited heavy baryons with light quarks in the spin-flavor symmetric representation

Lambda_btoSigma_c^{(*)}pi l{barnu}