Quark helicity distributions in transverse momentum space and transverse coordinate space

The transverse momentum dependent helicity distributions of valence quarks are calculated in the light-cone diquark model by adopting two different approaches. We use the model results to analyze the $P_{h\perp}$-dependent double spin asymmetries for $\pi^+$, $\pi^-$ and $\pi^0$ productions in semi-inclusive deep inelastic scattering, and find that the asymmetries agree with the CLAS data in one of the approaches. By taking the Fourier transform of the transverse momentum dependent helicity distributions, we obtain the helicity distributions of valence quarks in the transverse coordinate space, and then apply them further to predict the Bessel-weighted double spin asymmetries of $\pi^+$, $\pi^-$ and $\pi^0$ productions in semi-inclusive deep inelastic scattering at CLAS, COMPASS and HERMES for the first time. The shape of the Bessel-weighted double spin asymmetry thereby provides a direct probe on the transverse structure of longitudinally polarized quarks.Comment: References added, version published in PR

EMC effect in semi-inclusive deep-inelastic scattering process

By considering the $x$-dependence of $\pi^+$, $\pi^-$, $K^+$, $K^-$, $\Lambda$, $\bar{\Lambda}$, $p$, $\bar{p}$ hadron productions in charged lepton semi-inclusive deep inelastic scattering off nuclear target (using Fe as an example) and deuteron D target, % at $Q^2=5$ GeV$^2$, we find that $(\bar{\Lambda}^A/\Lambda^A)/(\bar{\Lambda}^D/\Lambda^D)$ and $({\bar{p}}^A/{p}^A)/({\bar{p}}^A/p^A)$ are ideal to figure out the nuclear sea content, which is predicted to be different by different models accounting for the nuclear EMC effect.Comment: 21 latex pages, 15 figure

Remark on the open string pair production enhancement

Recent studies by one of the present authors along with his collaborators in [1-4] show that there exist the so-called open string pair production for a possible simplest system of two Dp branes, placed parallel at a separation and with each carrying different electric flux, in Type II superstring theories. Further this pair production can be greatly enhanced when a magnetic flux, sharing no common field strength index with the electric one, is added, implying then $p \ge 3$. Given this, one may wonder if further enhancement can be achieved by adding more magnetic flux(es) in a similar fashion. In this paper, we explore this possibility. It turns out that adding more such magnetic flux diminishes rather than enhances the pair production rate. This actually implies that the largest enhancement occurs at $p = 3$ when the same realistic electric and magnetic fluxes are applied for all $p \ge 3$. Curiously one of D3 branes may be our own world and if so, the enhancement gives a possible opportunity to detect the pair production, therefore to test the underlying string theories.Comment: 14 pages, 0 figure

Unifying Contests: from Noisy Ranking to Ratio-Form Contest Success Functions

This paper proposes a multi-winner noisy-ranking contest model. Contestants are ranked in a descending order by their perceived outputs, and rewarded by their ranks. A contestant's perceivable output increases with his/her autonomous effort, but is subject to random perturbation. We establish, under plausible conditions, the equivalence between our model and the family of (winner-take-all and multi-winner) lottery contests built upon ratio-form contest success functions. Our model thus provides a micro foundation for this family of often studied contests. In addition, our approach reveals a common thread that connects a broad class of seeming disparate competitive activities and unifies them in the nutshell of ratio-form success functions.Multi-Winner Contest; Contest Success Function; Noisy Ranking

Contest design and optimal endogenous entry

This paper derives the effort-maximizing contest rule and the optimal endogenous entry in a context where potential participants bear fixed entry costs. The organizer is allowed to design the contest under a fixed budget with two strategic instruments: he sets the value of the prize purse, and arranges a monetary transfer (entry subsidy or fee) for each participating contestant. In other words, the budget can either be used to subsidize participation or an entry fee can be charged to fund the prize purse. The results show that the optimally designed contest attracts exactly two participating contestants in its unique subgame perfect equilibrium (when there is a positive fixed entry cost) and extracts all the surplus from participating contestants. The study also shows that the direction and amount of the monetary transfer depend on the magnitude of the entry cost: the contest organizer subsidizes entry when contestants bear substantial entry costs, but charges an entry fee to fund the prize purse whenever the entry cost is sufficiently low.Contest; Endogenous Entry; Entry Cost; Subsidy; Entry Fee

Unifying Contests: from Noisy Ranking to Ratio-Form Contest Success Functions

This paper proposes a multi-winner noisy-ranking contest model. Contestants are ranked in a descending order by their perceived outputs, and rewarded by their ranks. A contestant's perceivable output increases with his/her autonomous effort, but is subject to random perturbation. We establish, under plausible conditions, the equivalence between our model and the family of (winner-take-all and multi-winner) lottery contests built upon ratio-form contest success functions. Our model thus provides a micro foundation for this family of often studied contests. In addition, our approach reveals a common thread that connects a broad class of seeming disparate competitive activities and unifies them in the nutshell of ratio-form success functions.Multi-Winner Contest; Contest Success Function; Noisy Ranking