Angular distribution of the final particles in the decay $Λ_c^+\to K^- \, Δ(1232)^{++} \to K^- \, p \, π^+$ of the polarized charmed baryon is discussed. Asymmetries are proposed which allow for determination of the components of the $Λ_c^+$ polarization vector. The precession angle of the polarization in the process of baryon channeling in a bent crystal is directly related to these asymmetries. The decay rate and asymmetry parameter for the $Λ_c^+\to K^- \, Δ(1232)^{++}$ decay are calculated in the pole model and compared with experiment.
The non-leptonic two body decays of D mesons are studied in the framework of an improved factorization approximation. The final state interaction effects are taken into account assuming them dominated by nearby resonances. The agreement with experimental data is quite good. CP-violating asymmetries are predicted.
Fermilab experiment E791, measuring charmed hadron production in $π^- A$ interactions at 500 GeV with high statistics, has observed a strong asymmetry between the hadroproduction cross sections for leading $D$ mesons which contain projectile valence quarks and the nonleading charmed mesons without projectile valence quarks. Such correlations of the charge of the $D$ meson with the quantum numbers of the beam hadron explicitly contradict the factorization theorem in perturbative QCD which predicts that heavy quarks hadronize through a jet fragmentation function that is independent of the initia…
Motivated by the recent LHCb observation of $CP$ violation in charm, we study $CP$ violation in the charmed baryon decays. A simple method to search for the $CP$ violation relations in the flavor $SU(3)$ limit, which is associated with a complete interchange of $d$ and $s$ quarks, is proposed. With this method, hundreds of $CP$ violation sum rules in the doubly and singly charmed baryon decays can be found. As examples, the $CP$ violation sum rules in two-body charmed baryon decays are presented. Some of the $CP$ violation sum rules could help the experiment to find better observables. As bypr…
The Cabibbo allowed non-leptonic $B$-decays in two hadrons are studied, within the factorization hypothesis, in the framework of Isgur and Wise theory for the matrix elements of the $ΔB=-ΔC=\pm 1$ weak currents. The $SU(2)_{HF}$ symmetry relates $|ΔB|=1$ to $|ΔC|=1$ currents, which have been measured in the semileptonic strange decays of charmed particles. By assuming colour screening and allowing for $SU(3)$ invariant contributions from the annihilation terms with charmed final states one is able to comply with the present experimental knowledge.\\ The $CP$ violating asymmetries in neutral $B…
We present a model-independent analysis of CP violation, inspired by recent experimental observations, in charmed meson decays. The topological diagram approach is used to study direct CP asymmetries for singly Cabibbo-suppressed two-body hadronic decays of charmed mesons. We extract the magnitudes and relative phases of the corresponding topological amplitudes from available experimental information. In order to get more precise and reliable estimates of direct CP asymmetries, we take into account contributions from all possible strong penguin amplitudes, including the internal $b$-quark peng…
To probe the behavior of polarized gluons in the proton, we propose the charmed hadron, such as Lambda_c and D^*, production in the forthcoming RHIC experiments. We found that the spin correlation between the target proton and the produced Lambda_c baryon might be a good signal for testing models of the polarized gluon distribution in the proton.
Triggered by a recent LHCb measurement and prospects for Belle II, we derive U-spin symmetry relations between integrated CP asymmetries of three-body $Λ_c^+$ and $Ξ_c^+$ decays. The sum rules read $A_{CP}(Λ_c^+\rightarrow p K^- K^+) + A_{CP}(Ξ_c^+\rightarrow Σ^+ π^- π^+) = 0$, $A_{CP}(Λ_c^+\rightarrow p π^- π^+) + A_{CP}(Ξ_c^+\rightarrow Σ^+ K^- K^+) = 0$, and $A_{CP}(Λ_c^+\rightarrow Σ^+ π^- K^+) + A_{CP}(Ξ_c^+\rightarrow pK^-π^+) = 0$. No such U-spin sum rule exists between $A_{CP}(Λ_c^+\rightarrow p K^- K^+)$ and $A_{CP}(Λ_c^+\rightarrow p π^- π^+)$. All of these sum rules are associated w…
In order to extract information about behavior of polarized gluons in the nucleon, charmed hadron productions, i.e. D* meson and Lambda_c baryon productions, are studied in polarized pp reactions at BNL-RHIC energy. For these processes, the spin correlation asymmetry D_{LL} between the target proton and the produced charmed hadron, and its statistical sensitivity delta D_{LL} are calculated. From analyses on these processes, we found that the pseudo-rapidity distribution of D_{LL} in the limited transverse momentum region is quite effective for distinguishing the model of polarized gluons as w…
We study the $K^0_S-K^0_L$ asymmetries and $CP$ violations in charm-baryon decays with neutral kaons in the final state. The $K^0_S-K^0_L$ asymmetry can be used to search for two-body doubly Cabibbo-suppressed amplitudes of charm-baryon decays, with the one in $Λ^+_c\to pK^0_{S,L}$ as a promising observable. Besides, it is studied for a new $CP$-violation effect in these processes, induced by the interference between the Cabibbo-favored and doubly Cabibbo-suppressed amplitudes with the neutral kaon mixing. Once the new CP-violation effect is determined by experiments, the direct $CP$ asymmetry…
CP asymmetries for neutral charmed meson decays to CP eigenstates are carefully studied. The formulas and numerical results are presented. The impact on experiments is briefly discussed.
In order to extract the polarized strange quark density in proton, we studied the semi-inclusive $Λ_c$/$\barΛ_c$ leptoproduction in charged current DIS at THERA energies. We indicate that measurements of the spin correlation between the incident proton and the produced $Λ_c$/$\barΛ_c$ baryon gives us information about the polarized strange quark distribution.
In order to obtain information about the polarized strange quark distribution, we studied the semi-inclusive $Λ_c / \barΛ_c$ production in neutrino and polarized proton collisions. We found that these reactions are effective to clearly extract the polarization of strange quark by measuring the spin correlation between the target proton and the produced $Λ_c / \barΛ_c$ baryon.
We study the up-down asymmetries in the three-body anti-triplet charmed baryon decays of ${\bf B_c}\to{\bf B_n}MM' $ with the $SU(3)_f$ flavor symmetry, where ${\bf B_c}$ presents the anti-triplet charmed baryon of $(Ξ_c^0,-Ξ_c^+,Λ_c^+)$, while ${\bf B_n}$ and $M^{(')}$ denote octet baryon and meson states, respectively. By assuming the s-wave meson-pairs to be the dominant constituents in final state configurations, we can write the spin-dependent decay amplitude into parity-conserving and parity-violating parts, parametrized by 6 real parameters under $SU(3)_f$, respectively. Fitting these p…
To extract information about polarized gluons in the proton, production of charmed hadrons, in particular, Λ_c^+ baryon in pp collisions was studied. We calculated the transverse momentum distribution and the pseudo-rapidity distribution of the spin correlation asymmetry A_{LL} between the initial proton and the produced Λ_c^+. Those statistical sensitivities were also calculated under the condition of RHIC experiment. We found that the pseudo-rapidity distribution of A_{LL} is promising for testing the model of polarized gluons in the proton and also the spin-dependent fragmentation model of …
In the recent years, fruitful results on charmed baryons are obtained by BESIII, Belle and LHCb. We investigate the two-body non-leptonic decays of charmed baryons in the flavor $SU(3)$ symmetry. Hundreds of amplitude relations are clearly provided, and are classified according to the $I$-, $U$- and $V$-spin symmetries. Among them, some amplitude relations are tested by the experimental data, or used to predict the branching fractions based on the exact flavor symmetry without any other approximation. Some relations of $K^0_S-K^0_L$ asymmetries and $CP$ asymmetries are obtained under the $U$-s…
We analyze the decay processes of ${\bf B}_c \to {\bf B}_n M$ with the $SU(3)_F$ flavor symmetry and spin-dependent amplitudes, where ${\bf B}_c({\bf B}_n)$ and $M$ are the anti-triplet charmed (octet) baryon and nonet meson states, respectively. In the $SU(3)_F$ approach, it is the first time that the decay rates and up-down asymmetries are fully and systematically studied without neglecting the ${\cal O}(\overline{15})$ contributions of the color anti-symmetric parts in the effective Hamiltonian. Our results of the up-down asymmetries based on $SU(3)_F$ are quite different from the previous …
To extract information about polarized gluon distribution in the proton, charmed hadron, actually Λ_c^+, productions at RHIC experiment are studied. We found that the spin correlation asymmetry between the initial proton and the produced Λ_c^+ is enable us to distinguish parameterization models of polarized gluons.
We consider the decay of a polarized top quark into a stable $W^+$ boson and charmed-flavored (D) or bottom-flavored (B) hadrons, via $t(\uparrow)\rightarrow W^++D/B+X$. We study the angular distribution of the scaled-energy of B/D-hadrons at next-to-leading order (NLO) considering the contribution of bottom and gluon fragmentations into the heavy mesons B and D. To obtain the energy spectrum of B/D-hadrons we present our analytical expressions for the parton-level differential decay widths of $t(\uparrow)\rightarrow b+W^+(+g)$ at NLO. Comparison of our predictions with data at the LHC enable …
The polarized lepton pair forward-backward asymmetries in (B -> rho l^+ l^-) decay using a general, model independent form of the effective Hamiltonian is studied. The general expression for nine double-polarization forward-backward asymmetries are calculated. The study of the forward-backward asymmetries of the doubly-polarized lepton pair proves to be very useful tool in looking for new physics beyond the standard model.
We study the production cross sections for squarks and gluinos in collision of longitudinally polarized hadrons. The corresponding polarized partonic cross sections are computed in leading order supersymmetric QCD. The resulting asymmetries are evaluated for the polarized proton collider RHIC, as well as for hypothetical polarized options of the Tevatron and the LHC. These asymmetries turn out to be sizable over a wide range of supersymmetric particle masses, thus potentially opening a window to detailed sparticle spectroscopy at future polarized hadron colliders.
Polarized forward-backward asymmetries in the (B_s -> l^+ l^- gamma) decay are calculated using the most general, model independent form of the effective Hamiltonian, including all possible forms of interactions. The dependencies of the asymmetries on new Wilson coefficients are investigated. The detectability of the asymmetries at LHC is discussed.
We study the polarized lepton pair forward-backward asymmetries in (B -> K^* l^+ l^-) decay using a general, model independent form of the effective Hamiltonian. We present the general expression for nine double-polarization forward-backward asymmetries. It is shown that, the study of the forward-backward asymmetries of the doubly-polarized lepton pair is a very useful tool for establishing new physics beyond the standard model.
We discuss a possible explanation of the 25 year old mystery of the large transverse spin asymmetries found in many semi-inclusive hadron-hadron reactions. We obtain the first reliable information about the transverse polarized quark densities Delta_T q(x) and we find surprising implications for the usual, longitudinal, polarized DIS. The plan of the presentation is as follows: 1) A brief reminder about the internal structure of the nucleon. 2) The transverse asymmetries. 3) Why it is so difficult to explain the asymmetries. 4) Failure and then success using a new soft mechanism. 5) implicatio…
We discuss the possibilities of testing of perturbative quantum chromodynamics through azimuthal asymmetries in polarized ep in the context of future collider and fixed target facilities, such as Electron Ion Collider and TESLA-N.
We calculate various P-odd asymmetries appearing in the differential decay width for the cascade decay (Lambda_b -> Lambda(-> a+b) V^* (-> l^+ l^-)) with polarized and unpolarized heavy baryons including new vector type interactions and using the helicity amplitudes. It is obtained that the study of P-odd asymmetries can serve a good test for establishing new physics beyond the SM.
Double polarized forward-backward asymmetries in $B\rightarrow K_{1}(1270,1400)\ell^{+}\ell^{-}$ with $\ell=μ, τ$ decays are studied, using most general non-standard local four-fermi interactions, where the mass eigenstates $K_{1}(1270)$ and $K_{1}(1400)$ are the mixture of $^{1}{P}_{1}$ and $^{3}{P}_{1}$ states with the mixing angle $θ_{K}$. We have calculated the expressions of nine doubly polarized forward-backward asymmetries and it is presented that the polarized lepton pair forward-backward asymmetries are greatly influenced by the new physics. Therefore, these asymmetries are interestin…
Single spin asymmetries in polarized proton(antiproton) + proton -> pion + X have been measured to be large. They can be understood within perturbative QCD by introducing new k_perp and spin dependences in fragmentation and/or distribution functions. We discuss first how these effects in distribution functions alone can account for existing data and predict single spin asymmetries in other processes; then we see how similar effects in fragmentation functions alone can fit the existing data; finally we devise strategies to discriminate between the two contributions
Charge asymmetries for the charm meson production ($D^{*+}$--$D^{*-}$, $D^{*0}$--$\bar D^{*0}$ and $D^+_s$--$\bar D^-_s$) have been estimated for the COMPASS kinematic conditions in the framework of perturbative recombination model. Mass corrections have been taken into account in the calculations. The large asymmetry for $D^+_s$--$\bar D^-_s$ production has been predicted.
We derive the analog of the Wandzura-Wilczek relation for the light-cone distributions of polarized gluons in a transversely polarized nucleon. The short distance cross-section is entirely due to the intrinsic transverse momenta of gluon in the nucleon, in complete analogy to the quark case. Numerical estimate for the double spin transverse asymmetries at RHIC are presented.
The spin structure of the matrix element for the reactions $γ+ N\to Y_c +{D}^*$, where $Y_c=Λ_c^+(2285)$, $Σ_c(2455)$ are charmed baryons with spin 1/2, and $D^*(2010)$ is the vector charmed meson, can be parametrized, in collinear regime, in terms of three independent scalar amplitudes, which are functions of the photon energy $E_γ$, only. In framework of an effective Lagrangian approach generalized to charm photoproduction, we calculate the energy dependence of the differential cross section, the density matrix element of $\bar{D}^*$, $ρ_{11}$, the asymmetry $A_z$ in the collision of circula…
We consider several single spin asymmetries in inclusive, transversely polarized proton(antiproton) - proton processes as higher twist QCD contributions, taking into account spin and intrinsic transverse momentum effects in the quark distribution functions. This approach has been previously applied to the description of the single spin asymmetries observed in transversely polarized proton - proton -> pion + X reactions and all its parameters fixed: we give here predictions for new processes, which agree with experiments for which data are available, and suggest further possible measurements.
The production of $W^{\pm}$ and $Z^0$ bosons in collisions of longitudinally polarized protons allows to access various combinations of the polarized quark distributions from the study of double and single spin asymmetries. We compute the ${\cal O}(α_s)$ corrections to these asymmetries as function of the vector boson rapidity $y$ in the hadron-hadron centre-of-mass frame. Detailed studies of the numerical impact of the next-to-leading order corrections are presented. The theoretical uncertainties of an extraction of polarized quark distributions from future vector boson production data are in…
The utility of polarized electron beams for precision electroweak studies is described. Parity violating Moller scattering asymmetries in e-e- --> e-e- are discussed. Effects of electroweak radiative corrections and the running sin^2(theta_W(Q^2)) are reviewed. The sensitivity of E158 (a fixed target e-e- experiment at SLAC) and future e-e- collider studies to ``new physics'' is briefly outlined.
We study the double-lepton polarization asymmetries and single and double-lepton polarization forward backward asymmetries of the rare b \to s \ell^+ \ell^- mode within the Standard Model and in the Appelquist-Cheng-Dobrescu model, which is a new physics scenario with a single universal extra dimension. In particular, we examine the sensitivity of the observables to the radius R of the compactified extra-dimension, which is the new parameter in this new physics model.
We report on a calculation of one-loop weak corrections to polarized quark-gluon scattering and the corresponding crossed channels. Such contributions are suppressed formally by one power of alpha_s relative to W- or Z-mediated quark-quark scattering, but would enable the spin asymmetry of the gluon distribution to contribute to parity-violating asymmetries that will soon be investigated in polarized proton-proton scattering experiments at RHIC. In certain kinematic regions, gluon contributions to parity-violating asymmetries can be as large as 10% of the tree-level W- and Z-exchanges in quark…
Several parity violating left-right asymmetries in Møller electron-electron and muon-muon scattering are considered in the context of the electroweak standard model at tree level in fixed target and collider experiences. We show that in colliders the asymmetry with only one of the beam polarized is large enough to compensate the smaller cross section at high energies. We also show that these asymmetries are very sensitive to a doubly charged vector bilepton resonance but they are insensitive to scalar ones.
Predictions are made for azimuthal asymmetries in pion and kaon production from SIDIS off a longitudinally polarized deuterium target for HERMES kinematics, based on information on the 'Collins fragmentation function' from DELPHI data and on predictions for the transversity distribution function from non-perturbative calculations in the chiral quark-soliton model. There are no free parameters in the approach, which has been already successfully applied to explain the azimuthal asymmetries from SIDIS off polarized proton targets observed by HERMES and SMC.
A new handed interaction between quarks could be at the origin of some small parity violating effects in the inclusive production of one-jet in polarized $pp$ collisions. This interaction could originate from compositeness or from the presence of a new massive vector boson. The measurement of such asymmetries could be performed within a few years by using the RHIC collider as a polarized proton-proton collider.
A longitudinal double spin asymmetry for π^0 production has been measured by the PHENIX collaboration. The asymmetry is sensitive to the polarized gluon distribution and is indicated to be positive by theoretical predictions. We study a correlation between behavior of the asymmetry and polarized gluon distribution in neutral and charged pion production at RHIC.
We consider, in the electroweak standard model context, several left-right asymmetries in $μe$ elastic scattering at fixed target and collider experiments. For the former case, we show that the muon mass effects are important in a wide energy range. We also show that these asymmetries are sensitive to the electroweak mixing angle $θ_W$. The effect of an extra $Z'$ neutral vector boson appearing in a 331 model is also considered. The capabilities of these asymmetries in the search of this extra $Z'$ are addressed.
In this work, we carry out a global fitting for the two-body weak decays of antitriplet charmed baryons in both SU(3) respected and broken scenarios incorporating all the available data up to date. In the SU(3) irreducible representation approach (IRA), more amplitudes for irreducible representation terms are taken into account and the ranges for their coefficients in each scenarios are predicted. By a comparison among various fitting schemes in this work, experimental data prefer the SU(3) symmetry breaking scenario. Observables of interest, branching fractions and decay asymmetries of all th…
We consider the production of $W$ and $Z / γ^{*}$ gauge bosons in proton-proton collisions at a center-of-mass energy of $\sqrt{s} = 510 \mbox{GeV}$ available at RHIC at BNL, operating at high luminosity. We stress the importance of measuring the transverse double-spin asymmetries $A_{TT}$, in connection with available transversely polarized beams with a high degree of polarisation. We will discuss some theoretical issues related to the predicted asymmetries. These studies are contrasted to the 2017 RHIC running operation of transversely polarized beams of mid-rapidity $W$ and $Z$ boson produc…
Predictions for the single transverse spin asymmetry A_N in semi-inclusive DIS processes are given; non negligible values of A_N may arise from spin effects in the fragmentation of a polarized quark into a final hadron with a transverse momentum k_T with respect to the jet axis, the so-called Collins effect. The elementary single spin asymmetry of the fragmenting quark has been fixed in a previous paper, by fitting data on p(transv. polarized) + P -> pion + X, and the predictions given here are uniquely based on the assumption that the Collins effect is the only cause of the observed single sp…
We have used QCD and polarized deep-inelastic scattering data to construct x-dependent polarized parton distributions. These flavor dependent distributions evolve under the NLO DGLAP equations, satisfy positivity constraints and agree well with the data. We perform all of the analysis in x-space, avoiding difficulties with moments, and use these distributions to predict spin observables. The small-x behavior is sensitive to the model for the polarized gluon distribution.
We calculate the Sivers and $\cos2ϕ$ azimuthal asymmetries in $J/ψ$ production in polarized and unpolarized semi-inclusive $ep$ collision respectively, using the formalism based on transverse momentum dependent parton distributions (TMDs). Non-relativistic QCD based color octet model is employed for calculating the $J/ψ$ production rate. The Sivers asymmetry in this process directly probes the gluon Sivers function. The estimated Sivers asymmetry at $z=1$ is negative which is in good agreement with COMPASS data. We also investigate the effect of TMD evolution on the Sivers asymmetry. The $\cos…
We study the semi-leptonic and non-leptonic $B$ weak decays which are governed by the $B\rightarrow D^{(*)}$ transitions. The branching ratios, CP asymmetries (CPA) and polarization fractions (FA) of non-leptonic decays are investigated in the factorization approximation. The $B\rightarrow D^{(*)}$ form factors are estimated in the Salpeter method. Our estimation on branching ratios generally agree with the existent experimental data. For CPA and polarizations, comparisons among the FA results, the perturbative QCD predictions and experimental data are made.
We consider the leading order result for polarized leptoproduction, putting emphasis on transverse momentum dependent effects appearing in azimuthal asymmetries. Measurements of weighted cross sections enable extraction of the distribution of transversely polarized quarks. We focus on the distribution in a longitudinally polarized hadron and estimate the expected asymmetries in leptoproduction.
Predictions are made for single spin azimuthal asymmetries due to the Collins effect in pion production from semi-inclusive deeply inelastic scattering off transversely and longitudinally polarized targets for the HERMES and COMPASS experiments. The x-dependence of the asymmetries is evaluated using the parton distribution functions from the chiral quark-soliton model. The overall normalization of the predicted asymmetries is determined by the information on the Collins fragmentation function extracted from previous HERMES data on azimuthal asymmetries from a longitudinally polarized target. T…
New CP-violating asymmetries of decay leptons in $e^+\,e^-\;\ra\;t\,\bar{t}$, arising from electric and weak dipole couplings of $t\,\bar{t}$ to $γ$ and $Z$, are examined in the case of unpolarized and longitudinally polarized electrons. The new asymmetries measured together with the old ones can help to determine independently the real and imaginary parts of the electric as well as weak dipole couplings. Longitudinal beam polarization, if present, obviates the need for the simultaneous measurement of more than one asymmetry, and enhances considerably the sensitivity to the CP-violating parame…
We compare the $Q^{2}$ dependence of the polarized deep inelastic scattering proton asymmetry, driven by the leading order Altarelli Parisi evolution equations, to those arising from fixed order $α_{s}$ and $α_{s}^{2}$ approximations. It is shown that the evolution effects associated with gluons, which are not properly taken into account by the leading order approximation, cannot be neglected in the analysis of the most recent experimental data.
We analyze single-spin asymmetries (SSAs) in the leptoproduction of transversely polarized $Λ$ hyperons within the collinear twist-3 formalism. We calculate both the distribution and fragmentation terms in two different gauges (lightcone and Feynman) and show that the results are identical. This is the first time that the fragmentation piece has been analyzed for transversely polarized hadron production within the collinear twist-3 framework. In lightcone gauge we use the same techniques that were employed in computing the analogous piece in $p^\uparrow p\to π\,X$, which has become an importan…
We show that the measurement of some parity violating asymmetry in the production of a large ET jet could reveal the presence of a new hadrophilic Z' such as the one recently introduced to interpret possible departures from the Standard Model predictions both at LEP and at CDF. Such a measurement could be perform within a few years by the RHIC Spin Collaboration (RSC) using the Relativistic Heavy Ion Collider (RHIC) as a polarized proton-proton collider.
We present a calculation of inclusive polarised and unpolarised cross sections within pQCD and the factorisation scheme, taking into account the parton intrinsic motion, k_T, in distribution and fragmentation functions, as well as in the elementary dynamics. We show, in contradiction with earlier claims, that the Collins mechanism is suppressed and unable to explain the large asymmetries found in p(transv. polarized) p --> pion X at moderate to large Feynman x_F. The Sivers effect is not suppressed.
The polarized antiquark distributions in the proton can be measured by studying spin asymmetries in vector boson production in longitudinally polarized proton-proton collisions. The STAR and PHENIX experiments at BNL RHIC have reported first observations of single spin asymmetries in $W^\pm$-production most recently. We compute the QCD corrections to single and double spin asymmetries, taking account of the leptonic decay of the $W^\pm$ boson and of restrictions on the kinematical acceptance of the detectors. The QCD corrections have only a small impact on the asymmetries, such that a reliable…
The Weizsaecker-Williams transverse momentum dependent (TMD) gluon distributions can be probed in the production of a hard dijet in semi-inclusive DIS. This process is sensitive not only to the conventional but also to the linearly polarized gluon distribution. The latter gives rise to an azimuthal dependence of the dijet cross section and therefore can be distinguished from the former. Feasibility study of a measurement of these TMDs through dijet production at a future electron-ion collider shows that the extraction of the distribution of linearly polarized gluons with a statistical accuracy…
The $1/N_c$-expansion of QCD suggests large flavor asymmetries of the polarized antiquark distributions in the nucleon. This is confirmed by model calculations in the large-$N_c$ limit (chiral quark-soliton model), which give sizable results for $Δ\bar u (x) - Δ\bar d (x)$ and $Δ\bar u (x) + Δ\bar d (x) - 2 Δ\bar s (x)$. We compute the contributions of these flavor asymmetries to the spin asymmetries in hadron production in semi-inclusive deep-inelastic scattering. We show that the large flavor asymmetries predicted by the chiral quark-soliton model are consistent with the recent HERMES data f…
We discuss the double spin asymmetries in P-wave charmonium hadroproduction with non-zero transverse momenta at fixed target energies, $\sqrt{s}\simeq40$ GeV, within the framework of the NRQCD factorization approach. The size of the asymmetries and the projected statistical errors in a future option of HERA with longitudinally polarized protons scattering off a polarized target (HERA-$\vec N$) are calculated. Measurements of the $χ_{c1}$ and $χ_{c2}$ decays into dilepton plus photon should allow to distinguish between different parametrizations for the polarized gluon distribution in the proto…
A successful interpretation of the cross sections for elastic and inelastic vector meson production can be made if one assumes the underlying dynamics to be governed by hard partonic subprocesses. Extending these partonic approaches to longitudinally polarized electron-proton collisions, we estimate the expected production asymmetries at the HERA collider. The anticipated statistical errors on these asymmetries mostly turn out to be larger than the asymmetries themselves, such that an experimental observation of these asymmetries at HERA looks not feasible.
Estimates for longitudinal spin asymmetries which single out new polarized nucleon structure functions in deeply inelastic charged current interactions at HERA energies are given, exploiting their interpretation in terms of polarized quark distributions. These asymmetries turn out to be large and allow a measurement of the new polarized structure functions $g_1^{W}$ and $g_5^{W}$, which would add valuable tests and information on the spin content of quarks inside a polarized proton. We also show that single spin asymmetries in neutral current interactions are very small.
