Q^2-Dependence of the Proton's G_1 Structure Function Sum Rule

We study the $Q^2$ variation of the first moment of the nucleon's spin-dependent structure function $G_1$. As $Q^2 \rightarrow 0$ the moment is determined by the low energy theorem for Compton scattering. In the deep-inelastic region the moment is calculated using twist expansion to order $1/Q^2$. Based on these limits, we construct a formula which smoothly interpolates between the two regions.Comment: (revised), 8 pages in REVTEX, 1 figure, MIT-CTP-223

Constraining Right-Handed Scale Through Kaon Mixing in SUSY Left-Right Model

We study flavor-changing neutral current and CP violations in the minimal supersymmetric left-right model. We calculate the beyond-standard-model contributions to the neutral kaon mixing $\Delta M_K$ and $\epsilon$, and find possible to have a numerical cancelation between the contributions from the right-handed gauge boson and supersymmetric box diagram. With the cancelation, the right-handed $W$-boson mass scale can be lowered to about 2 TeV, well within the search limit of LHC.Comment: 12 pages, new figures adde

Subtle but significant effects of CO<inf>2</inf> acidified seawater on embryos of the intertidal snail, Littorina obtusata

Our understanding of the effects of ocean acidification on whole organism function is growing, but most current information is for adult stages of development. Here, we show the effects of reduced pH seawater (pH 7.6) on aspects of the development, physiology and behaviour of encapsulated embryos of the marine intertidal gastropod Littorina obtusata. We found reduced viability and increased development times under reduced pH conditions, and the embryos had significantly altered behaviours and physiologies. In acidified seawater, embryos spent more time stationary, had slower rotation rates, spent less time crawling, but increased their movement periodicity compared with those maintained under control conditions. Larval and adult heart rates were significantly lower in acidified seawater, and hatchling snails had an altered shell morphology (lateral length and spiral shell length) compared to control snails. Our findings show that ocean acidification may have multiple, subtle effects during the early development of marine animals that may have implications for their survival beyond those predicted using later life stages. © Inter-Research 2009

Gauge Link Structure in Quark-Quark Correlators in hard processes

Distribution functions in hard processes can be described by quark-quark correlators, nonlocal matrix elements of quark fields. Color gauge invariance requires inclusion of appropriate gauge links in these correlators. For transverse momentum dependent distribution functions, in particular important for describing T-odd effects in hard processes, we find that new link structures containing loops can appear in abelian and non-abelian theories. In transverse moments, e.g. measured in azimuthal asymmetries, these loops may enhance the contribution of gluonic poles. Some explicit results for the link structure are given in high-energy leptoproduction and hadron-hadron scattering.Comment: 9 pages, 9 figure

On the Q^2 Dependence of Measured Polarized Structure Funtions

We analyse the available data on the polarized asymmetries $A_1$ for proton, neutron and deuteron targets. We use a homogeneous and updated set of unpolarized structure functions to derive $g_1$ from $A_1$, and we accurately correct for the scaling violations in order to obtain $g_1(x,Q^2)$ with the same $Q^2$ for all $x$ values. The contribution to the $Q^2$ evolution of a possible large gluon polarized density is also considered. The implications for the Ellis-Jaffe and for the Bjorken sum rules are discussed.Comment: 11 pages (LaTex) + 4 figures (topdrawer, included at the end) CERN-TH 7023/9

An application of transverse-momentum-dependent evolution equations in QCD

The properties and behaviour of the solutions of the recently obtained $k_t$-dependent evolution equations are investigated. When used to reproduce transverse momentum spectra of hadrons in Semi-Inclusive DIS, an encouraging agreement with data is found. The present analysis also supports at the phenomenological level the factorization properties of the Semi-Inclusive DIS cross-sections in terms of $k_t$-dependent distributions. Further improvements and possible developments of the proposed evolution equations are envisaged.Comment: 6 pages, page format correcte

Implications of the Strange Spin of the Nucleon for the Neutron Electric Dipole Moment in Supersymmetric Theories

Supersymmetric model contributions to the neutron electric dipole moment arise via quark electric dipole moment operators, whose matrix elements are usually calculated using the Naive Quark Model (NQM). However, experiments indicate that the NQM does not describe well the quark contributions $\Delta q$ to the nucleon spin, and so may provide misleading estimates of electric dipole operator matrix elements. Taking the $\Delta q$ from experiment, we indeed find consistently smaller estimates of the neutron electric dipole moment for given values of the supersymmetric model parameters. This weakens previous constraints on CP violation in supersymmetric models, which we exemplify analytically in the case where the lightest supersymmetric particle (LSP) is a $U(1)$ gaugino $\tilde{B}$, and display numerically for other LSP candidates.Comment: 11 pages, uuencoded compressed postscript file including text and 3 figure

Spin-Dependent Twist-Four Matrix Elements from g_1 Data in the Resonance Region

Matrix elements of spin-dependent twist-four operators are extracted from recent data on the spin-dependent g_1 structure function of the proton and deuteron in the resonance region. We emphasize the need to include the elastic contributions to the first moments of the structure functions at Q^2 < 2 GeV^2. The coefficients of the 1/Q^2 corrections to the Ellis-Jaffe sum rules are found to be 0.04 \pm 0.02 and 0.03 \pm 0.04 GeV^2 for the proton and neutron, respectively.Comment: 10 pages REVTeX, 4 figure