118936305
Multiple scattering and energy loss in semi-inclusive deeply inelastic eA scattering
We calculate the multiple scattering effect on single hadron production in semi-inclusive lepton-nucleus deeply inelastic scattering. We show that the quantum interference of multiple scattering amplitudes leads to suppression in hadron productions. At the leading power in medium length, the suppression can be approximately expressed in terms of a shift in $z$ of the fragmentation function $D(z)$, and could be therefore interpreted as the collisional energy loss. We compare our calculation with existing experimental data. We also discuss the effect of quark mass on the suppression. Our approach can be extended to other observables in hadronic collisions.
15462403
Nuclear dependence in direct photon production.
We calculate the nuclear dependence of direct photon production in hadron-nucleus collisions. In terms of a multiple scattering picture, we factorize the cross section for direct photon production into calculable short-distance partonic parts times multiparton correlation functions in nuclei. We present the hadron-nucleus cross section as {ital A}{sup {alpha}} times the hadron-nucleon cross section. Using information on the multiparton correlation functions extracted from photon-nucleus experiments, we compute the value of {alpha} as a function of transverse momentum of the direct photon. We also compare our results with recent data from Fermilab experiment E706. {copyright} {ital 1996 The American Physical Society.}
30405678
Multiple scattering, parton energy loss, and modified fragmentation functions in deeply inelastic eA scattering
Modified quark fragmentation functions in deeply inelastic eA collisions and their QCD evolution equations are derived for the first time in the framework of multiple parton scattering. Induced radiation gives rise to additional terms in the evolution equations and thus softens the modified quark fragmentation functions. The results in the next-leading-twist depend on both diagonal and off-diagonal twist-four parton distributions and the combination of which clearly manifests the LPM interference pattern. The predicted modification depends quadratically on the nuclear size ( A2/3). Generalization to the case of hot QCD medium is also discussed.
42222465
Universality in the nuclear dependence coefficient alpha(q(T))
We derive the nuclear dependence coefficient alpha(q(T)) for Drell-Yan and J/psi production. We show that at small q(T), alpha(q(T)) is given by a universal functional form: alpha(q(T)) = a+bq(2)(T), and the parameters a and b are completely determined by either perturbatively calculable or independently measurable quantities. This universal functional form alpha(q(T)) is insensitive to A, and is consistent with existing data.
13900650
Nuclear dependence in the Drell-Yan transverse momentum distribution
We calculate the nuclear enhancement in the Drell-Yan transverse momentum distribution in hadron-nucleus collisions. In terms of the multiple scattering picture, we compute the contributions from double scattering. Applying the generalized factorization theorem, we express the nuclear enhancement in terms of twist-4 nuclear parton correlation functions. Using the known information on these twist-4 parton correlation functions, we estimate the nuclear enhancement for Drell-Yan pairs in the large q{sub T} region. We also discuss the source of nuclear suppression in the small q{sub T} region. {copyright} {ital 1998} {ital The American Physical Society}
119547297
TEST ON APPLICATION RANGE OF QCD SUM-RULES FROM BARYON SPECTROSCOPY
By considering the nonperturbative QCD effect via quark and gluon condensates, the confinement terms in effective q-q potential can automatically be given. A potential in the form of (Yukawa-type terms) where positive and negative signs appear alternatively in 's is proposed. To testify the validity range of QCD sum rules, the experimental baryon spectrum is fitted and the values of 's as well as their signs are obtained. It is found that in the baryon spectrum calculation, the terms of and are important and higher terms beyond can be neglected. Comparing these values with the result calculated from QCD sum rules, some agreements and disagreements are found.
199682466
Realistic Earth matter effects and a method to measure small \theta_{13} in the detection of supernova neutrinos
450968
Studying the scalar bound states of KK system in Bethe-Salpeter formalism
We study the possible bound states of the KK system in the Bethe-Salpeter formalism in the ladder and instantaneous approximations. We find that the bound states exist. However, these bound states have very small decay widths. Therefore, besides the possible KK component, there may be some other structures in the observed f{sub 0}(980) and a{sub 0}(980)
16156190
Dissipative potential induced by QCD at finite temperature and density
In the framework of QCD at finite temperature, we have obtained dissipative factors for the effective potential between q and {bar q} which would partly explain the J/{psi} suppression in the quark gluon plasma (QGP). The derivation of the dissipative potential in the QGP is presented and the case in the hadron matter (HM) is briefly discussed. The suppression effects are numerically estimated based on simple approximations and a comparison with that caused by the Debye screening mechanism is also presented. {copyright} {ital 1997} {ital The American Physical Society}
119367359
1 / m($Q$) corrections to the Bethe-Salpeter equation for $\Lambda_{Q}$ in the diquark picture
Corrections of order 1/m(Q) (Q = b or c) to the Bethe-Salpeter (BS) equation for Lambda(Q) are analyzed on the assumption that the heavy baryon Lambda(Q) is composed of a heavy quark and a scalar, light diquark. It is found that in addition to the one BS scalar function in the limit m(Q)-->infinity, two more scalar functions are needed at the order 1/m(Q). These can be related to the BS scalar function in the leading order in our model. The six form factors for the weak transition Lambda(b)-->Lambda(c) are expressed in terms of these wave functions and the results are consistent with HQET to order 1/m(Q). Assuming the kernel for the BS equation in the limit m(Q)-->infinity to consist of a scaler confinement term and a one-gluon-exchange term we obtain numerical solutions for the BS wave functions, and hence for the hb-th, form factors to order 1/m(Q). Predictions are given for the differential and total decay widths for Lambda(b)-->Lambda(c)l , and also for the nonleptonic decay widths for Lambda(b)-->Lambda(c) plus a pseudoscalar or vector meson, with QCD corrections being also included.