12579671
Heavy quarkonium production and polarization.
We present a perturbative QCD factorization formalism for the production of heavy quarkonia of large transverse momentum p(T) at collider energies, which includes both the leading-power (LP) and next-to-leading-power (NLP) contributions to the cross section in the m(Q)(2)/p(T)(2) expansion for heavy quark mass m(Q). We estimate fragmentation functions in the nonrelativistic QCD formalism and reproduce the bulk of the large enhancement found in explicit next-to-leading-order calculations in the color-singlet model. Heavy quarkonia produced from NLP channels prefer longitudinal polarization.
122409791
SCALE DEPENDENCE OF TWIST-3 CORRELATION FUNCTIONS
In this talk, we introduce two sets of twist-3 quark-gluon correlation functions that are relevant to transverse single spin asymmetries, and present corresponding evolution equations at the leading order in strong coupling constant, αs. The similarities and differences between the evolution of the leading power parton distributions and that of the twist-3 multiparton correlation functions are also discussed.
119264976
Inclusive b-jet production in heavy ion collisions at the LHC
Abstract Theoretical and experimental advances in understanding light jet production and modification in Pb + Pb reactions at s N N = 2.76 TeV have been a highlight of the LHC heavy ion program. At the same time, the detailed mechanisms of heavy quark propagation and energy loss in dense QCD matter are not yet fully understood. With this motivation, we present theoretical predictions for the nuclear-induced attenuation of the differential cross section for inclusive b-jet production in heavy ion collisions at the LHC for comparison to upcoming data. We find that for transverse momenta p T ≳ 75 GeV both hadronization and mass effects are negligible and this attenuation is comparable to the one observed for light jets. We discuss how the detailed b-jet quenching patterns can be used to gain new insight into the in-medium heavy flavor dynamics.
120322546
Process Dependence and the Sivers Effect in Inclusive and Semi-Inclusive Reactions
We perform an analysis of the the spin asymmetry for single inclusive jet production in proton-proton collisions collected by AnDY experiment and the Sivers asymmetry data from semi-inclusive deep inelastic scattering experiments. In particular, we consider the role color gauge invariance plays in determining the process-dependence of the Sivers effect. We find that after carefully taking into account the initial-state and final-state interactions between the active parton and the remnant of the polarized hadron, the calculated jet spin asymmetry based on the Sivers functions extracted from HERMES and COMPASS experiments is consistent with the AnDY experimental data. This provides a first indication for the process-dependence of the Sivers effect in different processes. We also make predictions for both direct photon and Drell-Yan spin asymmetry, to further test the process-dependence of the Sivers effect in future experiments.
45983064
Jet quenching phenomenology from soft-collinear effective theory with Glauber gluons.
We present the first application of a recently developed effective theory of jet propagation in matter, soft-collinear effective theory with Glauber gluons (SCET_{G}), to inclusive hadron suppression in nucleus-nucleus collisions at RHIC and the LHC. SCET_{G}-based splitting kernels allow us to go beyond the traditional energy loss approximation and unify the treatment of vacuum and medium-induced parton showers. In the soft gluon emission limit, we establish a simple analytic relation between the QCD evolution and energy loss approaches to jet quenching. We quantify the uncertainties associated with the implementation of the in-medim modification of hadron production cross sections and show that the coupling between the jet and the medium can be constrained with better than 10% accuracy.
119193850
Exploring the structure of the proton through polarization observables in lp→jet X
We present results for a complete set of polarization observables for jet production in lepton-proton collision, where the final-state lepton is not observed. The calculations are carried out in collinear factorization at the level of Born diagrams. For all the observables we also provide numerical estimates for typical kinematics of a potential future electron-ion collider. On the basis of this numerical study, the prospects for the transverse single target spin asymmetry are particularly promising. This observable is given by a certain quark-gluon correlation function, which has a direct relation to the transverse momentum dependent Sivers parton distribution.
117034934
Asymmetric Sneutrino Dark Matter in the NMSSM with Minimal Inverse Seesaw
We dynamically realize the supersymmetric inverse seesaw mechanism in the next to the minimal supersymmetic standard model (NMSSM) in a minimal form. The crucial observation is that the inclusion of a dimension-five operator ¯
118390328
The supersymmetric Standard Models with decaying and stable dark matters
We propose two supersymmetric Standard Models (SMs) with decaying and stable dark matter (DM) particles. To explain the SM fermion masses and mixings and have a heavy decay DM particle S, we consider the Froggatt–Nielsen mechanism by introducing an anomalous U(1)X gauge symmetry. Around the string scale, the U(1)X gauge symmetry is broken down to a Z2 symmetry under which S is odd while all the SM particles are even. S obtains a vacuum expectation value around the TeV scale, and then it can three-body decay dominantly to the second/third family of the SM leptons in Model I and to the first family of the SM leptons in Model II. Choosing a benchmark point in the constrained minimal supersymmetric SM with exact R parity, we show that the lightest neutralino DM is consistent with the CDMS II experiment. Considering S three-body decay and choosing suitable parameters, we show that the PAMELA and Fermi-LAT experiments and the PAMELA and ATIC experiments can be explained in Model I and Model II, respectively.
118390932
Decaying dark matter in the supersymmetric standard model with freeze-in and seesaw mechanims
Inspired by the decaying dark matter (DM) which can explain cosmic ray anomalies naturally, we consider the supersymmetric Standard Model with three right-handed neutrinos (RHNs) and R-parity, and introduce a TeV-scale DM sector with two fields ϕ1,2 and a Z3 discrete symmetry. The DM sector only interacts with the RHNs via a very heavy field exchange and then we can explain the cosmic ray anomalies. With the second right-handed neutrino N2 dominant seesaw mechanism at the low scale around 104 GeV, we show that ϕ1,2 can obtain the vacuum expectation values around the TeV scale, and then the lightest state from ϕ1,2 is the decay DM with lifetime around ∼1026s. In particular, the DM very long lifetime is related to the tiny neutrino masses, and the dominant DM decay channels to μ (and τ) are related to the approximate μ − τ symmetry. Furthermore, the correct DM relic density can be obtained via the freeze-in mechanism, the small-scale problem for power spectrum can be solved due to the decays of the R-parity odd meta-stable states in the DM sector, and the baryon asymmetry can be generated via the soft leptogensis.
118563295
Origins of the isospin violation of dark matter interactions
Light dark matter (DM) with a large DM-nucleon spin-independent scattering cross section and moreover proper isospin violation (ISV) f(n)/f(p) approximate to -0.7 may provide a way to understand the confusing DM.)M direct detection results. Further using the stringent astrophysical and collider constraints, we systematically investigate the origin of ISV,T first via general operator analyses and further via specifying three types of mediators: a light Z ' from chiral U(1)(x), an approximate spectator Higgs doublet (It can explain the W + jj anomaly simultaneously) and color triplets. In addition, although Z' from an exotic U(1)(x) mixing with U(1)(Y) generates only f(n) = 0, we can combine it with the conventional to achieve the proper ISV. As a concrete example, we propose the U(1)(x) model where the U(1)(x) charged light sneutrino is an inelastic DM, which dominantly annihilates to light dark states such as Z' with sub-GeV mass. The model can consistently (with other DM direct detection results) and safely interpret the recent GoGeNT annual modulation result.
118503601
Brightening the (130 GeV) Gamma-Ray Line
The gamma-ray line from dark matter (DM) annihilation is too weak to observe, but its observation will uncover much information, e.g., the DM mass and an anomalously large annihilation rate ∼ 0.1 pb into di-photon. In this work, we construct a minimal effective theory (EFT) incorporating DM and heavier charged particles. A large annihilation rate is obtained from operator coefficients with resonance or strong coupling enhancement.The EFT is stringently constrained by the XENON100 and WMAP data. Without resonance, Dirac DM or colored charged particles are ruled out. It is pointed out that the di-gluon mode may correctly determine the DM relic density. Interestingly, this framework also provides an origin for the Higgs di-photon excess at the LHC. We apply the general analysis to the NMSSM, which can elegantly interpret the tentative 130 GeV gamma-ray line. A top-window model is also proposed to explain the gamma-ray line.