Low mass lepton pair production in hadron collisions

The hadroproduction of lepton pairs with mass $Q$ and transverse momentum $Q_T$ can be described in perturbative QCD by the same partonic subprocesses as prompt photon production. We demonstrate that, like prompt photon production, lepton pair production is dominated by quark-gluon scattering in the region $Q_T>Q/2$. This leads to sensitivity to the gluon density in kinematical regimes that are accessible both at collider and fixed target experiments while eliminating the theoretical and experimental uncertainties present in prompt photon production.Comment: Talk given by M. Klasen at the International Conference on the Structure and Interactions of the Photon, PHOTON 99, Freiburg i. Brsg., Germany, May 23-27, 1999. To be published in the proceedings. 6 pages, 6 postscript figure

Providing social support at work matters and spills over to home:a multi-source diary study

Social support is in its essence a dyadic exchange process – it has important benefits for those who receive and those who provide support. In the present paper, we develop a model integrating insights from mattering and social exchange theories. We propose that self-determined support behaviors satisfy the provider’s feelings of mattering, which have a spillover effect on positive emotions at home. In addition, we hypothesize that positive emotions of the support receiver (co-worker) strengthen this indirect relationship. Hypotheses were tested in a sample of 67 dyads of co-workers (N = 280–305 data points). Results show that autonomous support behaviors positively relate to the provider’s positive emotions during the evening via mattering. Furthermore, employees felt that they mattered more and experienced more positive emotions when they supported co-workers with high (vs. low) positive emotions. These findings advance social support, mattering and spillover literatures by showing that brief episodes of helping behavior can satisfy mattering needs at work and help employees experience more positive emotions at home.</p

QCD Factorized Drell-Yan Cross Section at Large Transverse Momentum

We derive a new factorization formula in perturbative quantum chromodynamics for the Drell-Yan massive lepton-pair cross section as a function of the transverse momentum $Q_T$ of the pair. When $Q_T$ is much larger than the pair's invariant mass $Q$, this factorization formula systematically resums the logarithmic contributions of the type $\alpha_s^m \ln^m(Q_T^2/Q^2)$ to all orders in the strong coupling $\alpha_s$. When $Q_T\sim Q$, our formula yields the same Drell-Yan cross section as conventional fixed order QCD perturbation theory. We show that resummation is important when the collision energy $\sqrt{S}$ is large enough and $Q_T\gg Q$, and we argue that perturbative expansions are more stable and reliable in terms of the modified factorization formula.Comment: 36 pages, latex, including 16 figure

Response to Crocetti et al.

No abstract available

Toolbox for efficient development of high cell density perfusion process, integrated with continuous DSP

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Joint resummation in electroweak boson production

We present a phenomenological application of the joint resummation formalism to electroweak annihilation processes at measured boson momentum Q_T. This formalism simultaneously resums at next-to-leading logarithmic accuracy large threshold and recoil corrections to partonic scattering. We invert the impact parameter transform using a previously described analytic continuation procedure. This leads to a well-defined, resummed perturbative cross section for all nonzero Q_T, which can be compared to resummation carried out directly in Q_T space. From the structure of the resummed expressions, we also determine the form of nonperturbative corrections to the cross section and implement these into our analysis. We obtain a good description of the transverse momentum distribution of Z bosons produced at the Tevatron collider.Comment: 27 pages, LaTeX, 8 figures as eps files. Some additions to earlier version, this version as published in Phys. Rev. D66 (2002) 01401

Associated Production of a Z Boson and a Single Heavy-Quark Jet

The leading-order process for the production of a Z boson and a heavy-quark jet at hadron colliders is gQ -> ZQ (Q=c,b). We calculate this cross section at next-to-leading order at the Tevatron and the LHC, and compare it with other sources of ZQ events. This process is a background to new physics, and can be used to measure the heavy-quark distribution function.Comment: 15 pages, 9 figures. Version to appear in Phys. Rev.

Nuclear dependence coefficient α(A,qT)\alpha(A,q_T) for the Drell-Yan and J/ψ\psi production

Define the nuclear dependence coefficient $\alpha(A,q_T)$ in terms of ratio of transverse momentum spectrum in hadron-nucleus and in hadron-nucleon collisions: $\frac{d\sigma^{hA}}{dq_T^2}/ \frac{d\sigma^{hN}}{dq_T^2}\equiv A^{\alpha(A,q_T)}$. We argue that in small $q_T$ region, the $\alpha(A,q_T)$ for the Drell-Yan and J/$\psi$ production is given by a universal function:\ $a+b q_T^2$, where parameters a and b are completely determined by either calculable quantities or independently measurable physical observables. We demonstrate that this universal function $\alpha(A,q_T)$ is insensitive to the A for normal nuclear targets. For a color deconfined nuclear medium, the $\alpha(A,q_T)$ becomes strongly dependent on the A. We also show that our $\alpha(A,q_T)$ for the Drell-Yan process is naturally linked to perturbatively calculated $\alpha(A,q_T)$ at large $q_T$ without any free parameters, and the $\alpha(A,q_T)$ is consistent with E772 data for all $q_T$.Comment: latex, 28 pages, 10 figures, updated two figures, and add more discussion

Differential Cross Section for Higgs Boson Production Including All-Orders Soft Gluon Resummation

The transverse momentum $Q_T$ distribution is computed for inclusive Higgs boson production at the energy of the CERN Large Hadron Collider. We focus on the dominant gluon-gluon subprocess in perturbative quantum chromodynamics and incorporate contributions from the quark-gluon and quark-antiquark channels. Using an impact-parameter $b$-space formalism, we include all-orders resummation of large logarithms associated with emission of soft gluons. Our resummed results merge smoothly at large $Q_T$ with the fixed-order expectations in perturbative quantum chromodynamics, as they should, with no need for a matching procedure. They show a high degree of stability with respect to variation of parameters associated with the non-perturbative input at low $Q_T$. We provide distributions $d\sigma/dy dQ_T$ for Higgs boson masses from $M_Z$ to 200 GeV. The average transverse momentum at zero rapidity $y$ grows approximately linearly with mass of the Higgs boson over the range $M_Z < m_h \simeq 0.18 m_h + 18$~GeV. We provide analogous results for $Z$ boson production, for which we compute $\simeq 25$ GeV. The harder transverse momentum distribution for the Higgs boson arises because there is more soft gluon radiation in Higgs boson production than in $Z$ production.Comment: 42 pages, latex, 26 figures. All figures replaced. Some changes in wording. Published in Phys. Rev. D67, 034026 (2003

Vector boson production at hadron colliders: hard-collinear coefficients at the NNLO

We consider QCD radiative corrections to vector-boson production in hadron collisions. We present the next-to-next-to-leading order (NNLO) result of the hard-collinear coefficient function for the all-order resummation of logarithmically-enhanced contributions at small transverse momenta. The coefficient function controls NNLO contributions in resummed calculations at full next-to-next-to-leading logarithmic accuracy. The same coefficient function is used in applications of the subtraction method to perform fully-exclusive perturbative calculations up to NNLO.Comment: 13, pages, no figures. arXiv admin note: text overlap with arXiv:1106.465