45 research outputs found
Mechanical response functions of finite temperature Bose-Einstein Condensates
Using the Liouville space framework developed in nonlinear optics we
calculate the linear response functions and susceptibilities of Bose-Einstein
condensates (BEC) subject to an arbitrary mechanical force. Distinct signatures
of the dynamics of finite temperature BEC are obtained by solving the
Hartree-Fock-Bogoliubov theory. Numerical simulations of the position dependent
linear response functions of one dimensional trapped BEC in the time and the
frequency domains are presented.Comment: 9 figures. Submitted to Phys. Rev.
Generalized coherent state representation of Bose-Einstein condensates
We show that the quantum many-body state of Bose-Einstein condensates (BEC)
consistent with the time-dependent Hartree-Fock-Bogoliubov (TDHFB) equations is
a generalized coherent state (GCS). At zero temerature, the non-condensate
density and the anomalous non-condensate correlation are not independent,
allowing us to elimiate one of the three variables in the TDHFB.Comment: Submitted to Phys. Rev. A. No figures. Revised version fixes several
minor typos, and adds to some discussions; no change to the conclusio
Very rare, exclusive, hadronic decays in QCD factorization
We study exclusive hadronic decays of the electroweak bosons Z, W and h in the framework of QCD factorization. We show that the theory uncertainties in these channels are remarkably small compared to past applications of the QCD factorization framework. While the branching ratios are small, many of the modes are accessible at future colliders. The Higgs decays exhibit interesting dependences on the couplings due to the interferences of different diagram topologies, making the h → Vγ decays possible probes of the quark Yukawa couplings and the h → VZ decays probes of the coupling between the Higgs boson, a photon and a Z-boson
Heavy quarkonium: progress, puzzles, and opportunities
A golden age for heavy quarkonium physics dawned a decade ago, initiated by
the confluence of exciting advances in quantum chromodynamics (QCD) and an
explosion of related experimental activity. The early years of this period were
chronicled in the Quarkonium Working Group (QWG) CERN Yellow Report (YR) in
2004, which presented a comprehensive review of the status of the field at that
time and provided specific recommendations for further progress. However, the
broad spectrum of subsequent breakthroughs, surprises, and continuing puzzles
could only be partially anticipated. Since the release of the YR, the BESII
program concluded only to give birth to BESIII; the -factories and CLEO-c
flourished; quarkonium production and polarization measurements at HERA and the
Tevatron matured; and heavy-ion collisions at RHIC have opened a window on the
deconfinement regime. All these experiments leave legacies of quality,
precision, and unsolved mysteries for quarkonium physics, and therefore beg for
continuing investigations. The plethora of newly-found quarkonium-like states
unleashed a flood of theoretical investigations into new forms of matter such
as quark-gluon hybrids, mesonic molecules, and tetraquarks. Measurements of the
spectroscopy, decays, production, and in-medium behavior of c\bar{c}, b\bar{b},
and b\bar{c} bound states have been shown to validate some theoretical
approaches to QCD and highlight lack of quantitative success for others. The
intriguing details of quarkonium suppression in heavy-ion collisions that have
emerged from RHIC have elevated the importance of separating hot- and
cold-nuclear-matter effects in quark-gluon plasma studies. This review
systematically addresses all these matters and concludes by prioritizing
directions for ongoing and future efforts.Comment: 182 pages, 112 figures. Editors: N. Brambilla, S. Eidelman, B. K.
Heltsley, R. Vogt. Section Coordinators: G. T. Bodwin, E. Eichten, A. D.
Frawley, A. B. Meyer, R. E. Mitchell, V. Papadimitriou, P. Petreczky, A. A.
Petrov, P. Robbe, A. Vair
Search for solar flare neutrinos with the KamLAND detector
We report the result of a search for neutrinos in coincidence with solar flares from the GOES flare database. The search was performed on a 10.8 kton-year exposure of KamLAND collected from 2002 to 2019. This large exposure allows us to explore previously unconstrained parameter space for solar flare neutrinos. We found no statistical excess of neutrinos and established 90% confidence level upper limits of 8.4 × 10^7 cm^−2 (3.0 × 10^9 cm^−2) on the electron antineutrino (electron neutrino) fluence at 20 MeV normalized to the X12 flare, assuming that the neutrino fluence is proportional to the X-ray intensity.https://arxiv.org/abs/2105.0245
Scintillating bolometers based on ZnMoO4 and Zn100MoO4 crystals to search for 0ν2β decay of 100Mo (LUMINEU project): first tests at the Modane Underground Laboratory
The technology of scintillating bolometers based on zinc molybdate (ZnMoO4) crystals is under development within the LUMINEU project to search for decay of 100Mo with the goal to set the basis for large scale experiments capable to explore the inverted hierarchy region of the neutrino mass pattern. Advanced ZnMoO4 crystal scintillators with mass of ∼0.3 kg were developed and Zn100MoO4 crystal from enriched 100Mo was produced for the first time by using the low-thermal-gradient Czochralski technique. One ZnMoO4 scintillator and two samples (59 g and 63 g) cut from the enriched boule were tested aboveground at milli-Kelvin temperature as scintillating bolometers showing a high detection performance. The first results of the low background measurements with three ZnMoO4 and two enriched detectors installed in the EDELWEISS set-up at the Modane Underground Laboratory (France) are presented
Limits on astrophysical antineutrinos with the KamLAND Experiment
We report on a search for electron antineutrinos (n¯e) from astrophysical sources in the neutrino energy range
8.3–30.8 MeV with the KamLAND detector. In an exposure of 6.72 kton-year of the liquid scintillator, we observe 18
candidate events via the inverse beta decay reaction. Although there is a large background uncertainty from neutral
current atmospheric neutrino interactions, we find no significant excess over background model predictions.
Assuming several supernova relic neutrino spectra, we give upper flux limits of 60–110 cm−2 s
−1 (90% confidence
level, CL) in the analysis range and present a model-independent flux. We also set limits on the annihilation rates for
light dark matter pairs to neutrino pairs. These data improve on the upper probability limit of 8B solar neutrinos converting into , (90% CL) assuming an undistorted shape. This corresponds to a solar flux of 60 cm−2 s−1 (90% CL) in the analysis energy range.https://arxiv.org/abs/2108.0852
Random coincidence of 2\u3bd2\u3b2 decay events as a background source in bolometric 0\u3bd2\u3b2 decay experiments
Rejection of randomly coinciding 2ν2β events in ZnMoO4 scintillating bolometers
Random coincidence of 2ν2β decay events could be one of the main sources of background for 0ν2β decay in cryogenic bolometers due to their poor time resolution. Pulse-shape discrimination by using front edge analysis, the mean-time and χ2 methods was applied to discriminate randomly coinciding 2ν2β events in ZnMoO4 cryogenic scintillating bolometers. The background can be effectively rejected on the level of 99% by the mean-time analysis of heat signals with the rise time about 14 ms and the signal-to-noise ratio 900, and on the level of 98% for the light signals with 3 ms rise time and signal-to-noise ratio of 30 (under a requirement to detect 95% of single events). Importance of the signal-to-noise ratio, correct finding of the signal start and choice of an appropriate sampling frequency are discussed