We study the single-spin (left-right) asymmetry in single-inclusive pion production in hadronic scattering. This asymmetry is power-suppressed in the transverse momentum of the produced pion and can be analyzed in terms of twist-three parton correlation functions in the proton. We present new calculations of the corresponding partonic hard-scattering functions that include the so-called ''nonderivative'' contributions not previously considered in the literature. We find a remarkably simple structure of the results. We also present a brief phenomenological study of the spin asymmetry, taking into account data from fixed-target scattering and also the latest information available from Relativistic Heavy Ion Collider (RHIC). We make additional predictions that may be tested experimentally at RHIC.

In neutral cold quark matter that is sufficiently dense that the strange quark mass Ms is unimportant, all nine quarks (three colors; three flavors) pair in a color-flavor locked (CFL) pattern, and all fermionic quasiparticles have a gap. We argue that as a function of decreasing quark chemical potential µ or increasing Ms, there is a quantum phase transition from the CFL phase to a new "gapless CFL phase" in which only seven quasiparticles have a gap. The transition occurs where M 2 s /µ ≈ 2∆, with ∆ the gap parameter. Gapless CFL, like CFL, leaves unbroken a linear combinationQ of electric and color charges, but it is aQ-conductor with a nonzero electron density. These electrons and the gapless quark quasiparticles make the low energy effective theory of the gapless CFL phase and, consequently, its astrophysical properties qualitatively different from that of the CFL phase, even though its U (1) symmetries are the same. Both gapless quasiparticles have quadratic dispersion relations at the quantum critical point. For values of M 2 s /µ above the quantum critical point, one branch has conventional linear dispersion relations while the other branch remains quadratic, up to tiny corrections. PACS numbers:We know a lot about the properties of cold quark matter at sufficiently high baryon density from first principles. Quarks near their Fermi surfaces pair, forming a color superconductor [1]. In this letter we study how the favored pairing pattern at zero temperature depends on the strange quark mass M s , or equivalently on the quark chemical potential µ, using the pairing ansatz [2]Here ψ α a is a quark of color α = (r, g, b) and flavor a = (u, d, s); the condensate is a Lorentz scalar, antisymmetric in Dirac indices, antisymmetric in color (the channel with the strongest attraction between quarks), and consequently antisymmetric in flavor. The gap parameters ∆ 1 , ∆ 2 and ∆ 3 describe down-strange, up-strange and up-down Cooper pairs, respectively.To find which phases occur in realistic quark matter, one must take into account the strange quark mass and equilibration under the weak interaction, and impose neutrality under the color and electromagnetic gauge symmetries. The arguments that favor (1) are unaffected by these considerations, but there is no reason for the gap parameters to be equal once M s = 0. Previous work [3,4,5,6] compared the color-flavor-locked (CFL) phase (favored in the limit M s → 0 or µ → ∞), and the two-flavor (2SC) phase (favored in the limit M s → ∞). In this paper we show that in fact a transition between these phases does not occur. Above a critical M 2 s /µ, the CFL phase gives way to a new "gapless CFL phase", not to the 2SC phase. The relevant phases areTo impose color neutrality, it is sufficient to consider the U (1) 3 × U (1) 8 subgroup of the color gauge group generated by the Cartan subalgebra T 3 = diag(3 ) in color space [4]. We introduce chemical (color-electrostatic) potentials µ 3 and µ 8 coupled to the color charges T 3 and T 8 , and an electrostatic potential µ e couple...

We study the effect of WIMP annihilation on the temperature of a neutron star. We shall argue that the released energy due to WIMP annihilation inside the neutron stars might affect the temperature of stars older than 10 10 6 years, flattening out the temperature at 10 4 K for a typical neutron star.

We investigate dark matter candidates emerging in recently proposed technicolor theories. We determine the relic density of the lightest, neutral, stable technibaryon having imposed weak thermal equilibrium conditions and overall electric neutrality of the Universe. In addition we consider sphaleron processes that violate baryon, lepton and technibaryon number. Our analysis is performed in the case of a first order electroweak phase transition as well as a second order one. We argue that, in both cases, the new technibaryon contributes to the dark matter in the Universe.Finally we examine the problem of the constraints on these types of dark matter components from earth based experiments. * Electronic address: gudnason@nbi.dk † Electronic address: kouvaris@nbi.dk ‡ Electronic address: sannino@nbi.dk

We argue that observations of old neutron stars can impose constraints on dark matter candidates even with very small elastic or inelastic cross section, and self-annihilation cross section. We find that old neutron stars close to the galactic center or in globular clusters can maintain a surface temperature that could in principle be detected. Due to their compactness, neutron stars can accrete WIMPs efficiently even if the WIMP-to-nucleon cross section obeys the current limits from direct dark matter searches, and therefore they could constrain a wide range of dark matter candidates. * Electronic address: ckouvari@ulb.ac.be † Electronic address: Petr.Tiniakov@ulb.ac.be