Wed·Jul 27, 2016Wednesday·July 27, 2016

1. 01*

   Target and Beam-Target Spin Asymmetries in Exclusive Pion Electroproduction for $Q^2>1$ GeV${}^2$. I. $ep\to e{\pi }^{+}n$

   P.E. Bosted · M.J. Amaryan · S. Anefalos Pereira · H. Avakian · R.A. Badui · J. Ball · N.A. Baltzell · M. Battaglieri · V. Batourine · I. Bedlinskiy · A.S. Biselli · W.J. Briscoe and 106 other authors

   Beam-target double-spin asymmetries and target single-spin asymmetries were measured for the exclusive ${\pi }^{+}$ electroproduction reaction ${\gamma }^{\ast }p\to n{\pi }^{+}$. The results were obtained from scattering of 6 GeV longitudinally polarized electrons off longitudinally polarized protons using the CEBAF Large Acceptance Spectrometer at Jefferson Lab. The kinematic range covered is $1.1<W<3$ GeV and $1<Q^2<6$ GeV${}^2$. Results were obtained for about 6000 bins in $W$, $Q^2$, $\cos ({\theta }^{\ast })$, and ${\varphi }^{\ast }$. Except at forward angles, very large target-spin asymmetries are observed over the entire $W$ region. Reasonable agreement is found with phenomenological fits to previous data for $W<1.6$ GeV, but very large differences are seen at higher values of $W$. A GPD-based model is in poor agreement with the data. When combined with cross section measurements, the present results provide powerful constraints on nucleon resonance amplitudes at moderate and large values of $Q^2$, for resonances with masses as high as 2.4 GeV.

   nucl-exPRC(2017)·10 citations
2. 02*

   Energy dependence of $J/\psi$ production in Au+Au collisions at $\sqrt{s_{NN}}=$ 39, 62.4 and 200 GeV

   L. Adamczyk · J. K. Adkins · G. Agakishiev · M. M. Aggarwal · Z. Ahammed · I. Alekseev · A. Aparin · D. Arkhipkin · E. C. Aschenauer · M. U. Ashraf · A. Attri · G. S. Averichev and 328 other authors

   The inclusive $J/\psi$ transverse momentum ($p_T$) spectra and nuclear modification factors are reported at midrapidity ($|y|<1.0$) in Au+Au collisions at $\sqrt{s_{NN}}=$ 39, 62.4 and 200 GeV taken by the STAR experiment. A suppression of $J/\psi$ production, with respect to {\color{black}the production in $p+p$ scaled by the number of binary nucleon-nucleon collisions}, is observed in central Au+Au collisions at these three energies. No significant energy dependence of nuclear modification factors is found within uncertainties. The measured nuclear modification factors can be described by model calculations that take into account both suppression of direct $J/\psi$ production due to the color screening effect and $J/\psi$ regeneration from recombination of uncorrelated charm-anticharm quark pairs.

   ↳ hep-exnucl-exPLB(2017)·69 citations
3. 03*

   Neutrinoless Double Beta Decay in LRSM with Natural Type-II seesaw Dominance

   Prativa Pritimita🇮🇳 · Nitali Dash🇮🇳 · Sudhanwa Patra🇮🇳

   We present a detailed discussion on neutrinoless double beta decay within a class of left-right symmetric models where neutrino mass originates by natural type-II seesaw dominance. The spontaneous symmetry breaking is implemented with doublets, triplets and bidoublet scalars. The fermion sector is extended with an extra sterile neutrino per generation that helps in implementing the seesaw mechanism. The presence of extra particles in the model exactly cancels type-I seesaw and allows large value for Dirac neutrino mass matrix $M_D$. The key feature of this work is that all the physical masses and mixing are expressed in terms of neutrino oscillation parameters and lightest neutrino mass thereby facilitating to constrain light neutrino masses from $0\nu \beta \beta$ decay. With this large value of $M_D$ new contributions arise due to; i) purely left-handed current via exchange of heavy right-handed neutrinos as well as sterile neutrinos, ii) the so called $\lambda$ and $\eta$ diagrams. New physics contributions also arise from right-handed currents with right-handed gauge boson $W_R$ mass around $3$~TeV. From the numerical study, we find that the new contributions to $0\nu \beta \beta$ decay not only saturate the current experimental bound but also give lower limit on absolute scale of lightest neutrino mass and favor NH pattern of light neutrino mass hierarchy.

   ↳ hep-phnucl-exJHEP(2016)·29 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.