12485364
Jet broadening in deeply inelastic scattering
In deeply inelastic lepton-nucleus scattering (DIS), the average jet transverse momentum is broadened because of the multiple scattering in the nuclear medium. The size of jet broadening is proportional to the multi-parton correlation functions inside nuclei. We show that at leading order, jet broadening in DIS and nulcear enhancement in di-jet momentum imbalance and Drell-Yan $ $ share the same four-parton correlation functions. We argue that jet broadening in DIS provide an indenpendent measurement of the four-parton correlation functions and a test of QCD treatment of multiple scattering.
118914273
Direct photon production in a nuclear environment
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.
16223404
Gluon minijet production in nuclear collisions at high energies
We show explicitly that the leading soft gluon p{sub T} distribution, predicted by Kovner, McLerran, and Weigert after solving classical Yang-Mills equations, can be understood in terms of conventional QCD perturbation theory. We also demonstrate that the key logarithm in their result represents the logarithm in DGLAP evolution equations. {copyright} {ital 1999} {ital The American Physical Society}
15964205
Probing Multiparton Correlation Functions In Deeply Inelastic Scattering
We derive the transverse momentum broadening of the leading pions in deeply inelastic lepton-nucleus collisions. We argue that the measurement of such transverse momentum broadening can provide direct information on the multiple-parton correlation functions inside a nucleus. We also estimate the numerical values of such broadening at different values of xB and Q 2. 11.80.La, 12.38.Bx, 13.85.Ni, 24.80.-x Typeset using REVTEX
29148516
Multiple parton scattering in nuclei: Parton energy loss
Abstract Multiple parton scattering and induced parton energy loss are studied in deeply inelastic scattering (DIS) off nuclei. The effect of multiple scattering of a highly off-shell quark and the induced parton energy loss is expressed in terms of the modification to the quark fragmentation functions. We derive such modified quark fragmentation functions and their QCD evolution equations in DIS using the generalized factorization of higher twist parton distributions. We consider double-hard and hard-soft parton scattering as well as their interferences in the same framework. The final result, which depends on both the diagonal and off-diagonal twist-four parton distributions in nuclei, demonstrates clearly the Landau–Pomeranchuk–Migdal interference features and predicts a unique nuclear modification of the quark fragmentation functions.
119515469
Bethe-Salpeter equation for heavy baryons $\Omega_{Q}^{(*)}$ in the diquark picture
In the heavy quark limit, the heavy baryons omega(Q)((*)) (omega stands for Sigma, Xi or Omega and Q = b or c) are regarded as composed of a heavy quark and an axial vector, light diquark with good spin and isospin quantum numbers. Based on this diquark picture we establish the Bethe-Salpeter (BS) equation for omega(Q)((*)) in the limit where the heavy quark has infinite mass, m(Q)-->(infinity). It is found that in this limit there are three components in the BS wave function for omega(Q)((*)). Assuming the kernel to consist of a scalar confinement term and a one-gluon-exchange term we derive three coupled integral equations for the three BS scalar functions in the covariant instantaneous approximation. Numerical solutions for the three BS scalar functions are presented, including a discussion of their dependence on the various input parameters. These solutions are applied to calculate the Isgur-Wise functions xi(omega) and zeta(omega) for the weak transitions Omega(b)((*)) --> Omega(c)((*)). Using these we give predictions for the Cabibbo-allowed nonleptonic decay widths and up-down asymmetries for Omega(b)-->Omega(c)((*)) plus a pseudoscalar or vector meson. [S0556-2821(99)07909-6].
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.
119271994
$CP$ violation for $B^{0}\rightarrow \rho^{0}(\omega)\rho^{0}(\omega) \rightarrow \pi^+\pi^-\pi^+\pi^-$ in QCD factorization
In the QCD factorization (QCDF) approach we study the direct $CP$ violation in $\bar{B}^{0}\rightarrow\rho^0(\omega)\rho^0(\omega)\rightarrow\pi^+\pi^-\pi^+\pi^-$ via the $\rho-\omega$ mixing mechanism. We find that the $CP$ violation can be enhanced by double $\rho-\omega$ mixing when the masses of the $\pi^+\pi^-$ pairs are in the vicinity of the $\omega$ resonance, and the maximum $CP$ violation can reach 28{\%}. We also compare the results from the naive factorization and the QCD factorization.
120276294
Studies of heavy hadron physics
In the diquark picture, we establish Bethe-Salpeter equations for ground states of heavy baryons containing one heavy quark and two heavy quarks in the heavy quark limit, respectively. The Bethe-Salpeter equations for both heavy and light diquarks are also established. Assuming kernels to consist of a scalar confinement term and a one-gluon-exchange term we solve Bethe-Salpeter wave functions numerically in the covariant instantaneous approximation and give some applications including semileptonic and nonleptonic decay widths of heavy baryons, the average kinetic energy of the heavy quark in {Lambda}{sub Q}, {Sigma}{sub Q}{sup (*)}{yields}{Lambda}{sub Q}+{pi} decay widths, and heavy quark distribution functions. We also study possible molecular heavy bound states in the Bethe-Salpeter approach. Proof of QCD factorization for {Lambda}{sub b}{yields}{Lambda}{sub c}{pi} is presented in the framework of QCD factorization.
17365172
Heavy quark distribution functions in heavy baryons
Using the Bethe-Salpeter (B-S) equations for heavy baryons Lambda_Q, Sigma_Q, Xi_Q and Omega_Q (Q=b or c), which were established in previous work, we calculate the heavy quark distribution functions in these baryons. The numerical results indicate that these distribution functions have an obvious peak at some fraction, alpha_0, of the baryon's light-cone ``plus'' momentum component carried by the heavy quark, and that as m_Q becomes heavier this peak becomes sharper and closer to 1. The dependence of the distribution functions on various input parameters in the B-S model is also discussed. The results are seen to be qualitatively similar to an existing phenomenological model.