Fri·Aug 5, 2011Friday·August 5, 2011

1. 01*

   Nucleon Resonance Electrocouplings from the CLAS Meson Electroproduction Data

   I. G. Aznauryan🇦🇲 · V. D. Burkert🇺🇸 · V. I. Mokeev🇺🇸

   Transition helicity amplitudes ${\gamma }_{v}N{N}^{\ast }$ (electrocouplings) were determined for prominent excited proton states with masses below 1.8 GeV in independent analyses of major meson electroproduction channels: ${\pi }^{+}n$, ${\pi }^{0}p$ and ${\pi }^{+}{\pi }^{-}p$. Consistent results on resonance electrocouplings obtained from analyses of these exclusive reactions with different non-resonant contributions demonstrate reliable extraction of these fundamental quantities for states that have significant decays for either $N\pi$ or $N\pi \pi$ channels. Preliminary results on electrocouplings of $N^{\ast }$ states with masses above 1.6 GeV have become available from the CLAS data on ${\pi }^{+}{\pi }^{-}p$ electroproduction off protons for the first time. Comparison with quark models and coupled-channel approaches strongly suggest that $N^{\ast }$ structure is determined by contributions from an internal core of three constituent quarks and an external meson-baryon cloud at the distances covered in these measurements with the CLAS detector.

   nucl-exhep-phAIP Conf.Proc.(2012)·15 citations
2. 02*

   Deep Underground Science and Engineering Laboratory - Preliminary Design Report

   Kevin T. Lesko🇺🇸 · Steven Acheson🇺🇸 · Jose Alonso🇺🇸 · Paul Bauer🇺🇸 · Yuen-Dat Chan🇺🇸 · William Chinowsky🇺🇸 · Steve Dangermond🇺🇸 · Jason A. Detwiler🇯🇵 · Syd De Vries🇺🇸 · Richard DiGennaro🇺🇸 · Elizabeth Exter🇺🇸 · Felix B. Fernandez🇺🇸 and 39 other authors

   The DUSEL Project has produced the Preliminary Design of the Deep Underground Science and Engineering Laboratory (DUSEL) at the rehabilitated former Homestake mine in South Dakota. The Facility design calls for, on the surface, two new buildings - one a visitor and education center, the other an experiment assembly hall - and multiple repurposed existing buildings. To support underground research activities, the design includes two laboratory modules and additional spaces at a level 4,850 feet underground for physics, biology, engineering, and Earth science experiments. On the same level, the design includes a Department of Energy-shepherded Large Cavity supporting the Long Baseline Neutrino Experiment. At the 7,400-feet level, the design incorporates one laboratory module and additional spaces for physics and Earth science efforts. With input from some 25 science and engineering collaborations, the Project has designed critical experimental space and infrastructure needs, including space for a suite of multidisciplinary experiments in a laboratory whose projected life span is at least 30 years. From these experiments, a critical suite of experiments is outlined, whose construction will be funded along with the facility. The Facility design permits expansion and evolution, as may be driven by future science requirements, and enables participation by other agencies. The design leverages South Dakota's substantial investment in facility infrastructure, risk retirement, and operation of its Sanford Laboratory at Homestake. The Project is planning education and outreach programs, and has initiated efforts to establish regional partnerships with underserved populations - regional American Indian and rural populations.

   ↳ hep-exnucl-exphysics.geo-ph24 citations
3. 03*

   Measurement of the $\eta$ and $\omega$ Dalitz decays transition form factors in p-A collisions at 400 GeV/$c$ with the NA60 apparatus

   Antonio Uras · NA60 Collaboration

   The NA60 experiment has studied low-mass muon pairs production in proton-nucleus collisions at 400 GeV/$c$ at the CERN SPS. The mass spectrum is well described by the superposition of the two-body and Dalitz decays of the light neutral mesons $\eta$, $\rho$, $\omega$, ${\eta }^{\prime }$ and $\varphi$. The large collected statistics allows to isolate the contributions due to the Dalitz decays of the $\eta$ and $\omega$ mesons, from which the electromagnetic transition form factors of the two mesons have been extracted. The found values agree with the previous available measurements, improving their uncertainty thanks to the higher statistics. The results thus confirm the discrepancy with the prediction of the Vector Meson Dominance model in the case of the electromagnetic form factor of the $\omega$ meson.

   ↳ hep-exnucl-exJ.Phys.Conf.Ser.(2011)·5 citations
4. 04*

   R$\nu$MDM and Lepton Flavor Violation

   Yi Cai🇨🇳 · Xiao-Gang He🇹🇼 · Michael Ramsey-Musolf🇺🇸 · Lu-Hsing Tsai🇹🇼

   A model relating radiative seesaw and minimal dark matter mass scales without beyond the standard model (SM) gauge symmetry (R$\nu$MDM) is constructed. In addition to the SM particles, the R$\nu$MDM contains, a Majorana fermion multiplet $N_R$ and scalar multiplet $\chi$ that transform respectively as $(1,5,0)$ and $(1,6,-1/2)$ under the SM gauge group $SU(3{)}_C\times SU(2{)}_L\times U(1{)}_Y$. The neutral component $N_R^0$ plays the role of dark matter with a mass in the range of 9 to 10 TeV. This scale also sets the lower limit for the scale for the heavy degrees of freedom in $N_R$ and $\chi$ which generate light neutrino masses through the radiative seesaw mechanism. The model predicts an $N_R^0$-nucleus scattering cross section that would be accessible with future dark matter direct detection searches as well as observable effects in present and searches for charged lepton flavor violating processes, such as $l_i\to l_j\gamma$ and $\mu -e$ conversion.

   ↳ hep-phastro-ph.COhep-exnucl-ex+1JHEP(2011)·41 citations
5. 05*

   Low Mass Dimuon Production in p-A Collisions at $\sqrt{s}=27.5$ GeV with NA60

   Antonio Uras · NA60 Collaboration

   The NA60 experiment has studied low-mass muon pair production in proton-nucleus collisions with a system of Be, Cu, In, W, Pb and U targets using a 400 GeV/$c$ proton beam at the CERN SPS. The mass spectrum is well described by the superposition of the two-body and Dalitz decays of the light neutral mesons $\eta$, $\rho$, $\omega$, ${\eta }^{\prime }$ and $\varphi$. A new high-precision measurement of the electromagnetic transition form factors of the $\eta$ and $\omega$ mesons is presented, complemented with a measurement of the temperature parameter of the $\rho$ meson in cold nuclear matter. The $\text{pt}$ spectra for the $\omega$ and $\varphi$ mesons are extracted in the full $\text{pt}$ range accessible, up to $\text{pt}=2$ GeV/$c$. The nuclear dependence of the production cross sections for the $\eta$, $\omega$ and $\varphi$ mesons has been investigated in terms of the power law ${\sigma }_{\mathrm{pA}}\propto {\mathrm{A}}^{\alpha }$, and the $\alpha$ parameter was studied as a function of $\text{pt}$.

   ↳ hep-exnucl-exJ.Phys.G(2011)·6 citations
6. 06*

   Opportunities and Challenges for Theory in the N* program

   Craig D. Roberts🇺🇸

   The N*-program provides a path to understanding the essentially-nonperturbative fundamentals at the heart of the Standard Model: confinement and dynamical chiral symmetry breaking. Relating this data to QCD's basic degrees-of-freedom is a key challenge for theory. In tackling it, one steps immediately into the domain of relativistic quantum field theory where within the key phenomena can only be understood via nonperturbative methods. No one tool is yet fully equal to the challenge. Nonetheless, the last few years have seen significant progress in QCD-based theory, and the reaction models necessary to bridge the gap between that theory and experiment.

   ↳ nucl-thhep-lathep-phnucl-exAIP Conf.Proc.(2012)·15 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.