119220033
Global fitting of single spin asymmetry: an attempt
We present an attempt of global analysis of Semi-Inclusive Deep Inelastic Scattering (SIDIS) $$\ell p^\uparrow \to \ell' \pi X$$ data on single spin asymmetries and data on left-right asymmetry $A_N$ in $$p^\uparrow p \to \pi X$$ in order to simultaneously extract information on Sivers function and twist-three quark-gluon Efremov-Teryaev-Qiu-Sterman (ETQS) function. We explore different possibilities such as node of Sivers function in $x$ or $$k_\perp$$ in order to explain ``sign mismatch'' between these functions. We show that $$\pi^\pm$$ SIDIS data and $$\pi^0$$ STAR data can be well described in a combined TMD and twist-3 fit, however $$\pi^\pm$$ BRAHMS data are not described in a satisfactory way. This leaves open a question to the solution of the ``sign mismatch''. Possible explanations are then discussed.
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.
118744798
QCD Resummation for Heavy Quarkonium Production in High Energy Collisions
Using e+e−→J/Ψ+X as a case study, we explicitly demonstrate that the perturbatively calculated cross section for heavy quarkonium production in terms of the NRQCD factorization formalism has large logarithms as the collision energy s≫M, the heavy quarkonium mass. We propose a modified factorization formalism for the cross section, which systematically resums the large logarithms of the perturbatively calculated coefficient functions. The modified factorization formalism is perturbatively more stable and reliable for a much wider range of collision energies.
119668468
Transverse momentum broadening of vector bosons in heavy ion collisions at the LHC
We calculate in perturbative QCD the transverse momentum broadening of vector bosons in heavy ion collisions at the Large Hadron Collider (LHC). We predict transverse momentum broadening of $W/Z$ bosons constructed from their leptonic decay channels, which should be a clean probe of initial-state medium effect. We also predict the upper limit of transverse momentum broadening of J/$\psi$ and $\Upsilon$ production as a function of N$_{\rm part}$ at the LHC energy.
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.
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.
119201106
Semi-direct Gauge-Yukawa mediation
We propose semi-direct Gauge-Yukawa mediation of supersymmetry (SUSY) breaking. The messenger fields mediating SUSY breaking to the visible sector do not directly couple with the goldstino field, and instead they have gauge and Yukawa interactions with some primary messenger fields which couple directly with the goldstino fields. From the explicit Feynman diagram calculations for the SUSY breaking soft masses, we find that the SUSY particle spectra can be realistic. Especially, this generalization of semi-direct gauge mediation solves the massless gaugino mass problem since the holomorphic soft mass terms of the messenger fields can be generated by Yukawa couplings. We also provide some arguments that this scenario can be realized naturally in some dynamical SUSY-breaking models such as the ISS-like model.
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.
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.
119232543
On naturalness of the MSSM and NMSSM
A bstractWith a bottom-up approach, we consider naturalness in the MSSM and NMSSM. Assuming the light stops, the LHC gluino search implies that the degree of fine tuning in both models is less than 2.5%. Taking the LHC hints for the SM-like Higgs boson mass mh ~ 125 GeV seriously, we find that naturalness will favor the NMSSM. We study the Higgs boson mass for several scenarios in the NMSSM: (1) A large λ and the doublet-singlet Higgs boson mixing effect pushing upward or pulling downward mh. The former case can readily give the di-photon excess of the Higgs boson decay whereas the latter case can not. However, we point out that the former case has a new large fine-tuning related to strong λ−RGE running effect and vacuum stability. (2) A small λ and the mixing effect pushing mh upward. Naturalness status becomes worse and no significant di-photon excess can be obtained. In these scenarios, the lightest supersymmetric particle (LSP) as a dark matter candidate is strongly disfavored by the XENON100 experiment. Even if the LSP can be a viable dark matter candidate, there does exist fine-tuning. The above naturalness evaluation is based on a high mediation scale for supersymmetry breaking, whereas for a low mediation scale, fine-tuning can be improved by about one order.
118390410
Light dark matter from the U(1)(X) sector in the NMSSM with gauge mediation
Cosmic ray anomalies observed by PAMELA and Fermi-LAT experiments may be interpreted by heavy (TeV-scale) dark matter annihilation enhanced by Sommerfeld effects mediated by a very light (sub-GeV) U(1)(X) gauge boson, while the recent direct searches from CoGeNT and DAMA/LIBRA experiments may indicate a rather light (similar to 7GeV) dark matter with weak interaction. Motivated by these apparently different scales, we consider a gauge mediated next-to-the minimal supersymmetric standard model (NMSSM) entended with a light U(1)(X) sector plus a heavy sector ((H) over barh, Hh), which can provide both a light (similar to 7GeV) and a heavy (TeV-scale) dark matter without introducing any ad hoc new scale. Through the Yukawa coupling between Hh and the messager fields, the U(1)(X) gauge symmetry is broken around the GeV scale radiatively and a large negative m(S)(2) is generated for the NMSSM singlet S. Furthermore, the small kinetic mixing parameter between U(1)(X) and U(1)(Y) is predicted to be theta similar to 10(-5) - 10(-6) after integrating out the messengers. Such a light dark matter, which can have a normal relic density from the late decay of the right-handed sneutrino (assumed to be the ordinary next-to-the lightest supersymmetric particle and thermally produced in the early Universe), can serve a good candidate to explain the recent CoGeNT and DAMA/LIBRA results.