89,764 research outputs found
The azimuthal asymmetry of unpolarized dilepton production at the -pole
We calculate the Boer-Mulders effect contribution to the
azimuthal asymmetry of unpolarized dilepton production near the -pole. Based
on the tree-level expression in the transverse momentum dependent factorization
framework, we show that the corresponding asymmetry near the -pole is
negative, which is opposite to the asymmetry in the low region, dominated
by the production via a virtual photon. We calculate the asymmetry generated by
the Boer-Mulders effect near the -pole at RHIC, with GeV. We
find that the magnitude of the asymmetry is several percent, and therefore it
is measurable. The experimental confirmation of this sign change of the
asymmetry from the low region to the -pole provides direct evidence of
the chiral odd structure of quarks inside an unpolarized nucleon.Comment: comments and references added, journal versio
The puzzles in and decays: possible implications for R-parity violating supersymmetry
Recent experiments suggest that certain data of decays
are inconsistent with the standard model expectations. We try to explain the
discrepancies with R-parity violating suppersymmetry. By employing the QCD
factorization approach, we study these decays in the minimal supersymmetric
standard model with R-parity violation. We show that R-parity violation can
resolve the discrepancies in both and decays, and
find that in some regions of parameter spaces all these requirements, including
the CP averaged branching ratios and the direct CP asymmetries, can be
satisfied. Furthermore, we have derived stringent bounds on relevant R-parity
violating couplings from the latest experimental data, and some of these
constraints are stronger than the existing bounds.Comment: 24 pages, 6 figures and 5 tables. Text revised. Final version to
appear in PR
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The G protein-coupled receptor P2RY8 and follicular dendritic cells promote germinal center confinement of B cells, whereas S1PR3 can contribute to their dissemination.
The orphan Gα13-coupled receptor P2RY8 is mutated in human germinal center (GC)-derived lymphomas and was recently found to promote B cell association with GCs in a mouse model. Here we establish that P2RY8 promotes clustering of activated B cells within follicles in a follicular dendritic cell (FDC)-dependent manner. Although mice lack a P2RY8 orthologue, we show that mouse GC B cell clustering is also dependent on FDCs acting to support the function of a Gα13-coupled receptor. Mutations in GNA13 and its downstream effector ARHGEF1 are associated with the development of disseminated GC-derived lymphomas. We find that egress of Gna13 mutant GC B cells from lymph nodes in the mouse depends on sphingosine-1-phosphate receptor-3. These findings provide evidence that FDCs promote GC confinement of both human and mouse GC B cells via Gα13-dependent pathways, and they show that dissemination of Gα13-deficient GC B cells additionally requires an egress-promoting receptor
Ultra-low-phase-noise cryocooled microwave dielectric-sapphire-resonator oscillators with 1 x 10^-16 frequency instability
Two nominally identical ultra-stable cryogenic microwave oscillators are
compared. Each incorporates a dielectric-sapphire resonator cooled to near 6 K
in an ultra-low vibration cryostat using a low-vibration pulse-tube cryocooler.
The phase noise for a single oscillator is measured at -105 dBc/Hz at 1 Hz
offset on the 11.2 GHz carrier. The oscillator fractional frequency stability
is characterized in terms of Allan deviation by 5.3 x 10^-16 tau^-1/2 + 9 x
10^-17 for integration times 0.1 s < tau < 1000 s and is limited by a flicker
frequency noise floor below 1 x 10^-16. This result is better than any other
microwave source even those generated from an optical comb phase-locked to a
room temperature ultra-stable optical cavity.Comment: 4 pages, 5 figure
Superfluid Transition in a Chiron Gas
Low temperature measurements of the magnetic susceptibility of LSCO suggest
that the superconducting transition is associated with the disappearance of a
vortex liquid. In this note we wish to draw attention to the fact that
spin-orbit-like interactions in a poorly conducting layered material can lead
to a new type of quantum ground state with spin polarized soliton-like charge
carriers as the important quantum degree of freedom. In 2-dimensions these
solitons are vortex-like, while in 3-dimensional systems they are
monopole-like. In either case there is a natural mechanism for the pairing of
spin up and spin down solitons, and we find that at low temperatures there is a
cross-over transition as a function of carrier density between a state where
the solitons are free and a condensate state where the spin up and spin down
solitons in neighboring layers are paired.Comment: 10 pages, 1 figur
asymmetries in unpolarized semi-inclusive DIS
We use the Boer-Mulders functions parameterized from unpolarized
Drell-Yan data by the FNAL E866/NuSea Collaboration combined with recently
extracted Collins functions to calculate the asymmetries in
unpolarized semi-inclusive deeply inelastic scattering (SIDIS) processes both
for ZEUS at Hadron Electron Ring Accelerator (HERA) and Jefferson Lab
experiments (JLab), and to compare our results with their data. We also give
predictions for the asymmetries of SIDIS in the kinematical
regime of HERMES Collaboration, and the forthcoming JLab experiments. We
predict that the asymmetries of semi-inclusive production
are somewhat larger than that of production. We suggest to measure
these two processes separately, which will provide more detail information on
the Boer-Mulders functions as well as on the Collins functions.Comment: 9 latex pages, 18 figures, to appear in PR
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Privacy-Preserving iVector-Based Speaker Verification
This paper introduces an efficient algorithm to develop a privacy-preserving voice verification based on iVector and linear discriminant analysis techniques. This research considers a scenario in which users enrol their voice biometric to access different services (i.e., banking). Once enrolment is completed, users can verify themselves using their voice print instead of alphanumeric passwords. Since a voice print is unique for everyone, storing it with a third-party server raises several privacy concerns. To address this challenge, this paper proposes a novel technique based on randomization to carry out voice authentication, which allows the user to enrol and verify their voice in the randomized domain. To achieve this, the iVector-based voice verification technique has been redesigned to work on the randomized domain. The proposed algorithm is validated using a well-known speech dataset. The proposed algorithm neither compromises the authentication accuracy nor adds additional complexity due to the randomization operations
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