122072860
Delayed Pion Spectroscopy of Hypernuclei
New possibilities of hypernuclear studies at modern electron accelerators based on recently developed radio frequency photomultiplier tubes are discussed.
123272214
New (e,e′K+) hypernuclear spectroscopy with a high resolution kaon spectrometer
Abstract A new ( e , e ′ K + ) hypernuclear spectroscopy is proposed at Jefferson Lab. With a newly designed high resolution kaon spectrometer (HKS) and a new experimental configuration to reduce background electrons associated with bremsstrahlung, it is expected to realize much higher yield and hypernuclear mass resolution than those of the first successful experiment at Jefferson Lab Hall-C, which demonstrated the feasibility of hypernuclear electroproduction for Λ hypernuclear spectroscopy.
119255652
Bucking coil implementation on PMT for active canceling of magnetic field
Aerogel and water Cerenkov detectors were employed to tag kaons for a lambda hypernuclear spectroscopic experiment which used the (e,e'K{sup +}) reaction in experimental Hall C at Jefferson Lab (JLab E05-115). Fringe fields from the kaon spectrometer magnet yielded ~5 Gauss at the photomultiplier tubes (PMT) for these detectors which could not be easily shielded. As this field results in a lowered kaon detection efficiency, we implemented a bucking coil on each photomultiplier tubes to actively cancel this magnetic field, thus maximizing kaon detection efficiency.
39223572
Observation of a spin-flip M1 transition in 7(lambda)Li.
Using a large-acceptance germanium detector array (Hyperball), we have observed a spin-flip M1 gamma transition between the ground-state spin doublet of (7)(Lambda)Li (3/2(+)-->1/2(+)). The observed energy of 691.7+/-0.6(stat)+/-1.0(syst) keV provides crucial information on the strength of the spin-spin interaction between a Lambda and a nucleon. This is the first observation of well-identified hypernuclear gamma transitions using germanium detectors.
119236104
Fermion correction to the mass of the scalar glueball in QCD sum rule
Contributions of fermions to the mass of the scalar glueball $0^{++}$ are calculated at two-loop level in the framework of QCD sum rules. It obviously changes the coefficients in the operator product expansion (OPE) and shifts the mass of glueball.
19203912
Estimating the mass of the hidden charm $$1^+(1^{+})$$1+(1+) tetraquark state via QCD sum rules
By using QCD sum rules, the mass of the hidden charm tetraquark $$[cu][\bar{c}\bar{d}]$$[cu][c¯d¯] state with $$I^{G} (J^{P}) = 1^+ (1^{+})$$IG(JP)=1+(1+) (HCTV) is estimated, which presumably will turn out to be the newly observed charmonium-like resonance $$Z_c^+(3900)$$Zc+(3900). In the calculation, contributions up to dimension eight in the operator product expansion (OPE) are taken into account. We find $$m_{1^+}^c = (3912^{+306}_{-153}) \, \text {MeV}$$m1+c=(3912-153+306)MeV, which is consistent, within the errors, with the experimental observation of $$Z_c^+(3900)$$Zc+(3900). Extending to the b-quark sector, $$m_{1^+}^b = (10561^{+395{}^{}}_{-163}) \,\text {MeV}$$m1+b=(10561-163+395)MeV is obtained. The calculational result strongly supports the tetraquark picture for the “exotic” states of $$Z_c^+(3900)$$Zc+(3900) and $$Z_b^+(10610)$$Zb+(10610).