共查询到20条相似文献,搜索用时 125 毫秒
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高能h-A碰撞 总被引:2,自引:0,他引:2
本文在QCD修正的Drell-Yan机制和矢量介子中间态贡献下,利用NMC组的1-A深度非弹在0.00352<90MeV2/c2测量的结构函数比值RA(x,Q2),通过重标度模型解释了WA-78组对(π-,P)+A→μμ+X过程在2mμ≤mμμ≤1.5GeV和0.1≤xF≤0.6内的测量结果.将它们与在不同的m1l和xF区间测量的CIP组结果对比,解释了为什么靶核在前者中显示遮蔽效应面在后者中则显示出反遮蔽效应.指出通过重标度模型和其合理假定后,它们都与RA(x,Q2)直接相关,从而进一步揭示了1-A深度非弹中核效应与h-A ll产生过程中核效应之间的本质联系. 相似文献
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在组分夸克模型中重子共振态的光子激发下,通过数值计算核子上光子总吸收截面σ1/2和σ3/2,检验了Gerasimov–Drell–Heam(GDH)求和规则.这种计算包括了总计17个低激发的、非奇异重子共振态.发现纵横相干截面在随Q2变化的求和规则研究中扮演了重要角色.结果显示在94%可信度上这些共振态使GDH求和规则饱和.特别是在Q2=0和小Q2的区域,主要是共振态P33(1232)激发使求和规则饱和.在Q2=1.0GeV2以下,GDH积分有一个很强的Q2依赖性质,且在Q2=0.3GeV2附近变号.由于共振态贡献的迅速下降,当Q2>1.0GeV2时,GDH积分对Q2依赖变弱. 相似文献
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相对论组态混合效应对重子共振态的纵向跃迁振幅S1/2(Q2)的影响进行了讨论. 研究表明这种组态混合效应会对纵向跃迁振幅S1/2(Q2)起着明显的作用. 相似文献
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本文在QCD求和规则的基础上,通过分析π介子相关的遍举过程对QCD的检验情况,讨论了π介子分布振幅的行为,用一种尝试的分布振幅计算了Fπ(Q2)和Br(χ→2π),得到的Fπ(Q2)与实验数据相符合,Br(χ→2π)与实验数据在数量级上相符合. 相似文献
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本文讨论了QCD真空凝聚效应对强子结构函数中R比值(R≡σL/σI)的影响.利用背景场的基本思想,本文从有效拉氏量出发,计算了夸克凝聚对R比值的非微扰修正(Q-2项).结果显示本文所给出的修正在小x区较敏感. 相似文献
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利用推广的粒子-转子模型研究了159Tm负宇称Yrast态的能谱的Signature分离,B(M1)值以及动力学电四极矩Q(1)和Q(2),并同实验进行了比较,得到了较好的符合.着重分析了二级柯里奥利作用Hc对B(M1)值的Signature依赖性的影响,指出粒子-转子高级耦合项部分地等效于γ形变. 相似文献
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粒子–转子模型分析超形变转动带 总被引:1,自引:1,他引:0
利用三轴粒子-转子模型计算了193Tl超形变带γ跃迁能量,运动学转动惯量J(1)和动力学转动惯量J(2),并与实验值进行比较得到了满意的结果;预言了B(M1)值以及动力学电四极矩Q(1)和Q(2)指出在超形变带的分析中粒子-转子模型是一种可以采用的方法. 相似文献
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Krasovsky IV 《Physical review letters》2000,85(23):4920-4923
The spectral determinant det(H-varepsilonI) of the Azbel-Hofstadter Hamiltonian H is related to Onsager's partition function of the 2D Ising model for any value of magnetic flux Phi = 2piP/Q through an elementary cell, where P and Q are coprime integers. The band edges of H correspond to the critical temperature of the Ising model; the spectral determinant at these (and other points defined in a certain similar way) is independent of P. A connection of the mean of Lyapunov exponents to the asymptotic (large Q) bandwidth is indicated. 相似文献
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Ayari A Danneau R Requardt H Ortega L Lorenzo JE Monceau P Currat R Brazovskii S Grübel G 《Physical review letters》2004,93(10):106404
Using high-resolution x-ray scattering in the presence of an applied current, we report evidence for a dynamical decoupling between the two NbSe3 charge-density waves (CDWs), Q1 (T(C1)=145 K) and Q2 (T(C2)=59 K), coexisting below T(C2). Simultaneous and oppositely directed shifts of the relevant CDW superlattice spots develop above a threshold current which we identify as the depinning threshold I(C1) for the more strongly pinned upper CDW Q1 (I(C1) approximately 10I(C2)). In contrast with shifts induced by current conversion processes, the present effect is not current polarized and is not limited to the current-contact regions. We propose a model which explains this instability through a sliding-induced charge transfer between the two electronic reservoirs corresponding to the Q1 and Q2 CDWs. 相似文献
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We observe that the saturation model of deep inelastic scattering predicts a geometric scaling of the total gamma(*)p cross section in the region of small Bjorken variable x. The geometric scaling in this case means that the cross section is a function of only one dimensionless variable tau = Q(2)R(2)(0)(x), where the function R(0)(x) decreases with decreasing x. We show that the experimental data from HERA in the region x<0.01 confirm the expectations of this scaling over a very broad region of Q(2). We suggest that the geometric scaling is more general than the saturation model. 相似文献
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Amarian M Auerbach L Averett T Berthot J Bertin P Bertozzi W Black T Brash E Brown D Burtin E Calarco J Cates G Chai Z Chen JP Choi S Chudakov E Cisbani E de Jager CW Deur A DiSalvo R Dieterich S Djawotho P Finn JM Fissum K Fonvieille H Frullani S Gao H Gao J Garibaldi F Gasparian A Gilad S Gilman R Glamazdin A Glashausser C Goldberg E Gomez J Gorbenko V Hansen JO Hersman B Holmes R Huber GM Hughes E Humensky B Incerti S Iodice M Jensen S Jiang X Jones C Jones G Jones M Jutier C Ketikyan A 《Physical review letters》2004,93(15):152301
The generalized forward spin polarizabilities gamma(0) and delta(LT) of the neutron have been extracted for the first time in a Q2 range from 0.1 to 0.9 GeV2. Since gamma(0) is sensitive to nucleon resonances and delta(LT) is insensitive to the Delta resonance, it is expected that the pair of forward spin polarizabilities should provide benchmark tests of the current understanding of the chiral dynamics of QCD. The new results on delta(LT) show significant disagreement with chiral perturbation theory calculations, while the data for gamma(0) at low Q2 are in good agreement with a next-to-leading-order relativistic baryon chiral perturbation theory calculation. The data show good agreement with the phenomenological MAID model. 相似文献
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Volmer J Abbott D Anklin H Armstrong C Arrington J Assamagan K Avery S Baker OK Blok HP Bochna C Brash EJ Breuer H Chant N Dunne J Eden T Ent R Gaskell D Gilman R Gustafsson K Hinton W Huber GM Jackson H Jones MK Keppel C Kim PH Kim W Klein A Koltenuk D Liang M Lolos GJ Lung A Mack DJ McKee D Meekins D Mitchell J Mkrtchyan H Mueller B Niculescu G Niculescu I Pitz D Potterveld D Qin LM Reinhold J Shin IK Stepanyan S Tadevosyan V Tang LG van der Meer RL Vansyoc K Van Westrum D Vulcan W Wood S 《Physical review letters》2001,86(9):1713-1716
Separated longitudinal and transverse structure functions for the reaction 1H(e,e(')pi(+))n were measured in the momentum transfer region Q2 = 0.6--1.6 (GeV/c)(2) at a value of the invariant mass W = 1.95 GeV. New values for the pion charge form factor were extracted from the longitudinal cross section by using a recently developed Regge model. The results indicate that the pion form factor in this region is larger than previously assumed and is consistent with a monopole parametrization fitted to very low Q2 elastic data. 相似文献
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Stoler P 《Physical review letters》2003,91(17):172303
It is suggested that the falloff in Q2 of the P-->Delta magnetic form factor G*M is related to the recently observed falloff of the elastic electric form factor G(Ep)/G(Mp). Calculation is carried out in the framework of a generalized parton distribution model whose parameters are determined by fitting the elastic form factors F(1p) and F(2p) and isospin symmetry. When applied to the P-->Delta transition with no additional parameters, the shape of G*M is found to exhibit the requisite falloff with Q2. 相似文献
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Amarian M Auerbach L Averett T Berthot J Bertin P Bertozzi B Black T Brash E Brown D Burtin E Calarco J Cates G Chai Z Chen JP Choi S Chudakov E Cisbani E De Jager CW Deur A DiSalvo R Dieterich S Djawotho P Finn M Fissum K Fonvieille H Frullani S Gao H Gao J Garibaldi F Gasparian A Gilad S Gilman R Glamazdin A Glashausser C Goldberg E Gomez J Gorbenko V Hansen JO Hersman B Holmes R Huber GM Hughes E Humensky B Incerti S Iodice M Jensen S Jiang X Jones C Jones G Jones M Jutier C Ketikyan A 《Physical review letters》2004,92(2):022301
We have measured the spin structure functions g(1) and g(2) of 3He in a double-spin experiment by inclusively scattering polarized electrons at energies ranging from 0.862 to 5.058 GeV off a polarized 3He target at a 15.5 degrees scattering angle. Excitation energies covered the resonance and the onset of the deep inelastic regions. We have determined for the first time the Q2 evolution of Gamma(1)(Q2)= integral (1)(0)g(1)(x,Q2)dx, Gamma(2)(Q2)= integral (1)(0)g(2)(x,Q2)dx, and d(2)(Q2)= integral (1)(0)x(2)[2g(1)(x,Q2)+3g(2)(x,Q2)]dx for the neutron in the range 0.1< or =Q2< or =0.9 GeV2 with good precision. Gamma(1)(Q2) displays a smooth variation from high to low Q2. The Burkhardt-Cottingham sum rule holds within uncertainties and d(2) is nonzero over the measured range. 相似文献