Thermalization and the chromo-Weibel instability

Despite the apparent success of ideal hydrodynamics in describing the elliptic flow data which have been produced at Brookhaven National Lab's Relativistic Heavy Ion Collider, one lingering question remains: is the use of ideal hydrodynamics at times t < 1 fm/c justified? In order to justify its use a method for rapidly producing isotropic thermal matter at RHIC energies is required. One of the chief obstacles to early isotropization/thermalization is the rapid longitudinal expansion of the matter during the earliest times after the initial nuclear impact. As a result of this expansion the parton distribution functions become locally anisotropic in momentum space. In contrast to locally isotropic plasmas anisotropic plasmas have a spectrum of soft unstable modes which are characterized by exponential growth of transverse chromo-magnetic/-electric fields at short times. This instability is the QCD analogue of the Weibel instability of QED. Parametrically the chromo-Weibel instability provides the fastest method for generation of soft background fields and dominates the short-time dynamics of the system.Comment: 8 pages, 4 figures, Invited plenary talk given at the 19th International Conference on Ultrarelativistic Nucleus-Nucleus Collisions: Quark Matter 2006 (QM 2006), Shanghai, China, 14-20 Nov 200

Colour Coherence in Photon Induced Reactions

Colour coherence in hard photoproduction is considered using the Monte Carlo event generators PYTHIA and HERWIG. Significant effects in the parton shower are found using multijet observables for direct and resolved photon induced reactions. The particle flow in the interjet region of direct processes shows a strong influence of string fragmentation effects.Comment: 6 pages, LaTeX, 6 eps figures included, to appear in the proceedings of the workshop "Future Physics at HERA

Lines in quantum grassmannians

We study quantum lines in quantum grassmannians and prove that there are only finitely many corresponding to lines in usual grassmannians fixed by a maximal torus

The QCD trace anomaly

In this brief report we compare the predictions of a recent next-to-next-to-leading order hard-thermal-loop perturbation theory (HTLpt) calculation of the QCD trace anomaly to available lattice data. We focus on the trace anomaly scaled by T^2 in two cases: N_f=0 and N_f=3. When using the canonical value of mu = 2 pi T for the renormalization scale, we find that for Yang-Mills theory (N_f=0) agreement between HTLpt and lattice data for the T^2-scaled trace anomaly begins at temperatures on the order of 8 T_c while when including quarks (N_f=3) agreement begins already at temperatures above 2 T_c. In both cases we find that at very high temperatures the T^2-scaled trace anomaly increases with temperature in accordance with the predictions of HTLpt.Comment: 12 pages, 4 figures; v3 published versio

Hard-thermal-loop QCD Thermodynamics

Naively resummed perturbative approximations to the thermodynamic functions of QCD do not converge at phenomenologically relevant temperatures. Here we review recent results of a three-loop hard-thermal-loop perturbation theory calculation of the thermodynamic functions of a quark-gluon plasma for general N_c and N_f. We show comparisons of our recent results with lattice data from both the hotQCD and Wuppertal-Budapest groups. We demonstrate that the three-loop hard-thermal-loop perturbation result for QCD thermodynamics agrees with lattice data down to temperatures T ~ 2 T_c.Comment: 8 pages, 2 figures; Talk given at the Symposium on "High Energy Strong Interactions", Aug. 9-13, 2010, Yukawa Institute for Theoretical Physics, Kyoto, Japan; submitted to Prog. Theor. Phys. Supp

Heavy quarkonium production in a strong magnetic field

It is well known that in noncentral heavy-ion collisions a transient strong magnetic field is generated in the direction perpendicular to the reaction plane. The maximal strength of this field is estimated to be $eB \sim m^2_{\pi} \sim 0.02 \text{GeV}^2$ at the RHIC and $eB \sim 15 m^2_{\pi} \sim 0.3 \text{GeV}^2$ at the LHC. We investigate the effects of a strong magnetic field on $B$ and $D$ mesons, focusing on the changes of the energy levels and the masses of the bound states. Using the Color Evaporation Model we discuss the possible changes in the production of $J/\psi$ and $\Upsilon$.Comment: 18 pages, 7 figure

Abusive Debt Collection - A Model Statute for Virginia

Among the many by-products of the phenomenal growth of consumer credit in the last two decades has been the attempt on the part of existing legal institutions to grapple with the problem of coercive debt collection. The existence of the problem is no longer disputed, and the nature and extent of the abuse surrounding debt collection practices has been the subject of voluminous commentary. Given the dynamics of the competing interests involved when a creditor attempts to collect a just debt which the debtor is unable to pay, an essential conflict requiring regulated resolution becomes apparent. Unfortunately, the problem is compounded when it is recognized that the debt may not be validly due and owing, that the debtor may have a defense, real or perceived, or that the debtor may merely be unwilling to pay, either in fact or as perceived by the creditor. Since the information available to either party is imperfect, it frequently is impossible to determine the actual dimensions of the conflict as viewed from the varying perceptions of the parties. The inevitable result of the inability of either party to assess accurately the optimum means by which any given conflict should be resolved has been the development of a series of abusive collection tactics and practices utilized by debt collectors in attempts to recover outstanding obligations. The extent of such practices is difficult to determine. When questioned about their techniques, firms engaging in debt collection universally report that they have promulgated policies against harassment in an effort to maintain customer good will. To the extent that such statements can be accepted without question, the abusive practices which do occur must be attributed to overly aggressive individual collectors possibly concerned with default ratios as a reflection on their job performance. Such collectors, of course, are reluctant to discuss these practices candidly, making it difficult to measure accurately the extent of harassment tactics by surveying the collection industry. On the other hand, compiling accurate empirical data on collection practices through a consumer sample is equally difficult. Debtors have a tendency to exaggerate descriptions of contacts made by the debt collector. They may be acutely sensitive to any collection attempt, no matter how harmless it might seem to an objective outsider, and their reports may reflect their resentment. Those engaging in debt collection should be entitled to a presumption of regularity in view of the absence of data revealing the true extent of offensive collection practices. It may be assumed that the great majority of all lending institutions, credit sellers, and collection agencies employ acceptable methods in their attempts to encourage the debtor to pay. Nevertheless, in today\u27s credit-oriented society, attention must be directed toward the small minority of firms involved in coercive and overreaching activities. With over $180 billion of credit currently outstanding and an average per capita indebtedness of$900, it is reasonable to assume that few consumers are untouched by the credit industry. Since credit plays such a major role in consumer transactions, it is vital that collection practices be effectively regulated

Workforce Development in the South West Voluntary and Community Sectors:Skill Shortages Study

The Voluntary Sector National Training Organisation, now the National  Workforce Development Hub, describes the Voluntary and Community  Sector  as  diverse  and  covering  a  variety  of  different  organisations.  Organisations range from traditional charities, to companies that trade to  support their social aims, through to informal community organisations.  The sector also includes federations, or networks of local groups working  under national umbrellas.  Voluntary and community sector organisations  provide  a  wide  range  of  services  and  activities  and  many  of  the  organisations are involved in the delivery of learning, whether through  accredited training or informal learning.  The Government has increasingly recognised the importance of Voluntary  and  community  sector  organisations  and  the  key  role  that  they  play  nationally,  regionally  and  locally.    Initiatives  to  support  the  sector,  underpinned by funding, have been undertaken and the Government has  been  active  in  encouraging  and  commissioning  research  and  strategic  planning  in  the  sector,  in  particular  emphasising  the  importance  of  developing the skills, capacities and potential of the workforce.  Sector organisations generally display a strong commitment to training  and workforce development.  However, in spite of this commitment and  the presence of a high proportion of well‐qualified workers, skills gaps,  that is skills lacking in the current workforce, and skills shortages caused  by recruitment difficulties, are present in the sector.  There are also skills  gaps and shortages in the volunteer workforce