119450769
Isospin dependence of liquid–gas phase transition in hot asymmetric nuclear matter
Abstract By using the Furnstahl, Serot and Tang's model, the effect of density dependence of the effective nucleon–nucleon– ρ -meson (NN ρ ) coupling on the liquid–gas phase transition in hot asymmetric nuclear matter is investigated. A limit pressure p lim has been found. We found that the liquid–gas phase transition cannot take place if p > p lim . The binodal surface for density dependent NN ρ coupling situation is addressed.
121034531
Strange hadronic matter in a chiral model
The strange hadronic matter with nucleon, Λ-hyperon and Ξ-hyperon is studied by using a chiral symmetry model in a mean-field approximation. The saturation properties and stabilities of the strange hadronic matter are discussed. The result indicates a quite large strangeness fraction (fS) region where the strange hadronic matter is stable against particle emission. In the large fS region, the Ξ component dominates, resulting in a deep minimum in the curve of the binding energy per baryon EB versus the strangeness fraction fS with (EB, fS) (-26.0 MeV, 1.23).
123370023
Chiral symmetry restoration of nuclear matter
The phase transition of chiral symmetry restoration of nuclear matter is studied in the chiral SU(3) quark mean field model. For some kinds of confining potentials, there exists a critical density ρc. When the baryon density is larger than ρc, nuclear matter will be in the phase of chiral symmetry restoration. At critical density, the physical quantities change discontinuously. The critical density will become larger when the vector part of the confining potential increases.
121124456
An Extended Chiral SU(3) Quark Model
The chiral SU(3) quark model is extended by including the vector meson exchanges to describe the short range interactions. The phase shifts of NN scattering are studied in this model. Compared with the results of the chiral SU(3) quark model in which only the pseudo-scalar and scalar chiral fields are considered, the phase shifts of 1S0 wave are obviously improved.
118632293
Nucleon magnetic form factors with non-local chiral effective Lagrangian
Chiral perturbation theory is a useful method to investigate the hadron properties. We apply the non-local chiral effective Lagrangian to study the nucleon magnetic form factors. The octet and decuplet intermediate states are included in the one-loop calculation. With the modified propagators and non-local interaction, the loop integral is convergent. The obtained proton and neutron magnetic form factors are both reasonable up to relatively large Q2.
117796835
Static three-body potential in baryons
The first principle of quantum chromodynamics is used to calculate the static perturbative three-body potential between three valence quarks in baryons, which is gauge invariant and flavor-dependent, and of magnitude of the same order as the next non-leading static q-q potential. Its effect on an S-state baryon composed of three valence quarks of equal mass may be viewed as a slight increase of the constituent quark masses with respect to those in mesons.
74871422
Measurement of $B^0 \to D_s^- K^0_S\pi^+$ and $B^+ \to D_s^- K^+K^+$ branching fractions
We report a measurement of the $B^0$ and $B^+$ meson decays to the $D_s^-K^0_S \pi^+$ and $D_s^- K^+K^+$ final states, respectively, using $657 \times 10^{6} B\overline{B}$ pairs collected at the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. Using the $D_s^-\to \phi\pi^-$, $K^{*}(892)^0 K^-$ and $K^0_S K^-$ decay modes for the $D_s$ reconstruction, we measure the following branching fractions: ${\cal B}(B^0\to D_s^{-}K^0_S\pi^+)=[0.47 \pm 0.06 (\mathrm {stat}) \pm 0.05 (\mathrm {syst})]\times 10^{-4}$ and ${\cal B}(B^+\to D_s^-K^+K^+)= [0.93 \pm 0.22 (\mathrm {stat})\pm 0.10 (\mathrm {syst})]\times 10^{-5}$. We find the ratio of the branching fraction of $B^+\to D_s^-K^+K^+$ to that of the analogous Cabibbo favored $B^+\to D_s^-K^+\pi^+$ decay to be ${\cal R}_{\cal B} = 0.054 \pm 0.013 ({\rm stat}) \pm 0.006 ({\rm syst})$, which is consistent with the na\"{\i}ve factorization model. We also observe a deviation from the three-body phase-space model for both studied decays.
209835620
High-statistics study of neutral-pion pair production in two-photon collisions
The differential cross sections for the process gamma gamma -> pi(0)pi(0) have been measured in the kinematic range 0.6 GeV < W < 4.1 GeV, vertical bar cos theta* vertical bar < 0.8 in energy and pion scattering angle, respectively, in the gamma gamma center-of-mass system. The results are based on a 223 fb(-1) data sample collected with the Belle detector at the KEKB e(+)e(-) collider. The differential cross sections are fitted in the energy region 1.7 GeV < W < 2.5 GeV to confirm the two-photon production of two pions in the G wave. In the higher-energy region, we observe production of the chi(c0) charmonium state and obtain the product of its two-photon decay width and branching fraction to pi(0)pi(0). We also compare the observed angular dependence and ratios of cross sections for neutral-pion and charged-pion pair production to QCD models. The energy and angular dependence above 3.1 GeV are compatible with those measured in the pi(+)pi(-) channel, and in addition we find that the cross section ratio, sigma(pi(0)pi(0))/sigma(pi(+)pi(-)), is 0.32 +/- 0.03 +/- 0.05 on average in the 3.1-4.1 GeV region.
119717624
Asymmetric nuclear matter at finite temperature and density
Asymmetric nuclear matter is studied by using an effective nuclear model in a mean-field approximation. The density, temperature, and asymmetric parameter dependence of the effective baryon mass is discussed. The liquid-gas phase transition of a system with two independent conserved charges (baryon number and isospin) is studied using the stability conditions on the free energy and Gibbs conditions for phase equilibrium. The critical temperature is calculated with and without $\ensuremath{\rho}$ meson contribution, respectively.
15056774
NN interactions in the extended chiral SU(3) quark model
Abstract The chiral SU (3) quark model is extended to include coupling between vector chiral field and quarks. By using this model, the phase shifts of NN scattering for different partial waves are studied. The results are very similar to those of the chiral SU (3) quark model calculation, in which one gluon exchange (OGE) plays dominate role in the short range part of the quark–quark interactions. Only in the 1 S 0 case, the one channel phase shifts of the extended chiral SU (3) quark model are obviously improved.
55341209
OPERATION OF PEP IN A LOW EMITTANCE MODE
I’KI’ has I)crn IISC~ as a. source of synchrol.ron ra.diat.ion with at, 11nd~lat0r beam line operating parasitically tlurirtg particle pllysics runs at 14.5 GeV bca.m energy. ‘I’hc l)ossibi!ltlF. of using PEP in a dcdicntcrl mode for synchr0(1.011 racllat,lon have tenon considered. Since a lower bran1 r~~crgy is preferred in this cast, PEP has hcen succrssfully op~~ratctt at. 8 GeV where I.hr uricc,nplctl l~ra111 ctnittance is 27 null ratl. It is of int.erest to r~lucc this clnit.tance fnrther wit.h a tliffrrent opt,ics ha.ving strongrr horizont~al focnssing. This has I)een (lone by increasing tile horizontal heMron phase aclvauw per cell from 56” 1.0 I 00” resuIt.ing in an cmit,t,ance of about 9 1llJ1 rnd. To keep t,he strc~ngth of the sext 11p0lcs and their crV a l>eam was successfully injected and n.ccn~iiula.led. ‘I’he hol.izontal arid ~.~rtit.nl eniit tanccs were n~easllrc~tl Itsing the photon J)talll of the 58 111 long un(lulator hnnl lint- iI found to be 12.1 ant1 1 2 nnl ~,ntl. This is close to t,hr exp~ct,r~l value of 9.9 11111 ract for the SI~III of the two. The I)ealll lift, t.imr was over 30 110111.S at low cllrrcnts. Diffrrcn! mcltiods of rctliicing this emit.tancr cvcn further are invcst.iRat,e(l. Jncrcasillg tllc horizonl.al tlalnping pal.tition front .J, = rto .r, = 2 looks nlost prornisil.~g. This does uot rquirc new hardware bnl can IJ~ achieved WIllI a. s111nt1 increase of the RF-frequency of about ‘I kHz. Such au operation mode has been co~nputed ant1 tracked. The dyna.mic accrpt.ancr is very large and the expectrtl nnc~onplcd eniitt.ance is ,I.3 *11n rad at 8 (;eV.