共查询到20条相似文献,搜索用时 15 毫秒
1.
Rahul Basu 《Pramana》2003,61(5):787-792
This is a summary of the talks on QCD, not including QCD at finite temperature or density (which are discussed elsewhere)
presented at the QCD 2002 meeting held at IIT, Kanpur. I have attempted to give only an overview of the talks since the details
may be found in the individual contributions. 相似文献
2.
Mrinal Dasgupta 《Pramana》2004,62(3):675-678
The recent discovery and resummation of a class of single logarithmic effects (non-global logs), has a significant impact
on several QCD observables ranging from the classic Sterman-Weinberg jet definition to currently studied event shapes and
rapidity gap observables. The discovery of the above effects overturns, for example, the common wisdom that hadronic energy
flow in limited inter-jet regions is dictatedprimarily by the colour flow of the underlying hard partonic subprocess. We discuss some features of non-global logs and the rapid
progress being made in estimating and controlling such corrections. 相似文献
3.
Prakash Mathews Rahul Basu D. Indumathi E. Laenen Swapan Majhi Anuradha Misra Asmita Mukherjee W. Vogelsang 《Pramana》2004,63(6):1367-1379
This is the report of the QCD working sub-group at WHEPP-8 which was part of the QCD and QGP working group. Discussion and
work on some aspects of resummation and parton distribution are reported. 相似文献
4.
V Ravindran Pankaj Agrawal Rahul Basu Satyaki Bhattacharya J Blümlein V Del Duca R Harlander D Kosower Prakash Mathews Anurag Tripathi 《Pramana》2006,67(5):983-992
This is the report of the subgroup QCD of Working Group-4 at WHEPP-9. We present the activities that had taken place in the
subgroup and report some of the partial results arrived at following the discussion at the working group meetings. 相似文献
5.
We study a model of quark confinement defined by the vanishing of colour currents. The model is shown to be equivalent to
quantum chromodynamics and this equivalence is interpreted as due to the compositeness of the colour gluons. The Green’s functions
of the theory are found to contain nontrivial structure only for colour singlet composites which can be identified with hadrons. 相似文献
6.
The talk summarizes some new results of lattice investigations of QCD at finite temperature. The topics discussed cover the
flavor dependence of the critical temperature and the equation-of-state as well as hadronic correlation functions. 相似文献
7.
A general analysis of the Slavnov-Taylor identity connecting the triple gluon and ghost-ghost-gluon vertices and its consequences
for two momentum subtraction (symmetric and asymmetric) renormalization schemes are given. It is shown that in the asymmetric
scheme proposed in this paper the relation
follows directly from the identity for a simple and natural definition of the renormalization constants. Explicit one-loop
expressions for the renormalization constants
in an arbitrary covariant gauge, including quark masses are given in support of the general analysis. 相似文献
8.
We propose a framework for quantitative evaluation of dynamical tendency for polarization in an arbitrary random variable that can be decomposed into a pair of orthogonal subspaces. The method uses measures based on comparisons of given dynamics to its counterpart with statistically independent components. The formalism of previously considered X-distributions is used to express the aforementioned comparisons, in effect putting the former approach on solid footing. Our analysis leads to the definition of a suitable correlation coefficient with clear statistical meaning. We apply the method to the dynamics induced by pure-glue lattice QCD in local left–right components of overlap Dirac eigenmodes. It is found that, in finite physical volume, there exists a non-zero physical scale in the spectrum of eigenvalues such that eigenmodes at smaller (fixed) eigenvalues exhibit convex X-distribution (positive correlation), while at larger eigenvalues the distribution is concave (negative correlation). This chiral polarization scale thus separates a regime where dynamics enhances chirality relative to statistical independence from a regime where it suppresses it, and gives an objective definition to the notion of “low” and “high” Dirac eigenmode. We propose to investigate whether the polarization scale remains non-zero in the infinite volume limit, in which case it would represent a new kind of low energy scale in QCD. 相似文献
9.
Claudio Rebbi 《Journal of statistical physics》1986,43(5-6):1117-1127
Some recent Monte Carlo calculations for quantum chromodynamics, performed on Euclidean lattices of rather large extent, are
reviewed. The purpose of the calculations is to provide accurate determinations of quantities, such as interquark potentials
or mass eigenvalues, which are relevant for hadronic spectroscopy. Results obtained in quenched QCD on 163×32 lattices are illustrated, and a discussion of computational resources and techniques required for the calculations is
presented. 相似文献
10.
ALPHA Collaboration Marco Guagnelli Jochen Heitger Rainer Sommer Hartmut Wittig 《Nuclear Physics B》1999,560(1-3):465-481
We explain how masses and matrix elements can be computed in lattice QCD using Schrödinger functional boundary conditions. Numerical results in the quenched approximation demonstrate that good precision can be achieved. For a statistical sample of the same size, our hadron masses have a precision similar to what is achieved with standard methods, but for the computation of matrix elements such as the pseudoscalar decay constant the Schrödinger functional technique turns out to be much more efficient than the known alternatives. 相似文献
11.
Thomas Schäfer 《Pramana》2003,60(4):697-709
We review recent work on the phase structure of QCD at very high baryon density. We introduce the phenomenon of color superconductivity
and discuss the use of weak coupling methods. We study the phase structure as a function of the number of flavors and their
masses. We also introduce effective theories that describe low energy excitations at high baryon density. Finally, we comment
on the possibility of kaon condensation at very large baryon density. 相似文献
12.
Davison E. Soper 《Pramana》2003,61(5):793-802
I review some issues related to short distance QCD and its relation to the experimental program of the large hadron collider
(LHC) now under construction in Geneva. 相似文献
13.
We review the basic concepts of perturbative quantum chromodynamics (QCD) and relativistic hydrodynamics, and their applications to hadron production in high energy nuclear collisions. We discuss results from the Relativistic Heavy Ion Collider (RHIC) in light of these theoretical approaches. Perturbative QCD and hydrodynamics together explain a large amount of experimental data gathered during the first decade of RHIC running, although some questions remain open. We focus primarily on practical aspects of the calculations, covering basic topics like perturbation theory, initial state nuclear effects, jet quenching models, ideal hydrodynamics, dissipative corrections, freeze-out and initial conditions. We conclude by comparing key results from RHIC to calculations. 相似文献
14.
We compute the leading logarithmic behaviour of the cross-section for the production of a pseudoscalar Higgs boson in gluon–gluon fusion to all-orders in perturbation theory, in the limit of large partonic centre of mass energy. We also calculate the Higgs rapidity distribution to the same accuracy. We include the contributions of top and bottom quarks, together with their interference. Our results are given in terms of single and double integrals, evaluated explicitly up to next-to next-to leading order (NNLO). We use our results to improve the known NNLO inclusive cross-section computed in the effective theory where the fermions in the loop are integrated out. The size of finite fermion mass effects on the inclusive cross-section is found to be small, reaching a few percent only for large values of the pseudoscalar mass. 相似文献
15.
We geometrize a generic (abelian and non-abelian) gauge coupling within the framework of a Kaluza–Klein theory, by choosing a suitable matter-field dependence on the extra coordinates. We first extend the Nöther theorem to a multidimensional spacetime, the Cartesian product of a 4-dimensional Minkowski space and a compact homogeneous manifold (whose isometries reflect the gauge symmetry). On such a “vacuum” configuration, the extra-dimensional components of the field momentum correspond to the gauge charges. Then we analyze the structure of a Dirac algebra for a spacetime with the Kaluza–Klein restrictions. By splitting the corresponding free-field Lagrangian, we show how the gauge coupling terms arise. 相似文献
16.
C. D. White 《Contemporary Physics》2018,59(2):109-125
Three of the four fundamental forces in nature are described by so-called gauge theories, which include the effects of both relativity and quantum mechanics. Gravity, on the other hand, is described by General Relativity, and the lack of a well-behaved quantum theory – believed to be relevant at the centre of black holes, and at the Big Bang itself – remains a notorious unsolved problem. Recently a new correspondence, the double copy, has been discovered between scattering amplitudes (quantities related to the probability for particles to interact) in gravity, and their gauge theory counterparts. This has subsequently been extended to other quantities, providing gauge theory analogues of e.g. black holes. We here review current research on the double copy, and describe some possible applications. 相似文献
17.
We provide a method for the all order computation of small x contributions at the leading logarithmic level to cross-sections which are differential in rapidity. The method is based on a generalization to rapidity distributions of the high energy (or kT) factorization theorem hitherto proven for inclusive cross-sections. We apply the method to Higgs production in gluon–gluon fusion, both with finite top mass and in the infinite mass limit: in both cases, we determine all-order resummed expressions, as well as explicit expressions for the leading small x terms up to NNLO. We use our result to construct an explicit approximate analytic expression of the finite-mass NLO rapidity distribution and an estimate of finite-mass corrections at NNLO. 相似文献
18.
19.
Rohini M. Godbole Agnes Grau Rohit Hegde Giulia Pancheri Yogi Srivastava 《Pramana》2006,66(4):657-668
In this note, we summarize and compare various model predictions forpp total cross-section σ
tot
pp
, giving an estimate of the range of predictions for the total cross-section, σ
tot
pp
expected at the LHC. We concentrate on the results for σ
tot
pp
obtained in a particular QCD based model of the energy dependence of the total cross-section, including the effect of soft
gluon radiation. We obtain the range of predictions in this model by exploring the allowed range of model parameters. We further
give a handy parametrisation of these results which incidentally spans the range of various other available predictions at
the LHC as well 相似文献
20.
Subhasis Chattopadhyay 《Pramana》2004,63(6):1195-1210
In this talk, I review the recent results from RHIC and discuss their significance. 相似文献