Tue·Dec 26, 2017Tuesday·December 26, 2017

1. 01*

   Measurement of prompt and nonprompt charmonium suppression in PbPb collisions at 5.02 TeV

   CMS Collaboration

   The nuclear modification factors of J/$\psi$ and $\psi$(2S) mesons are measured in PbPb collisions at a centre-of-mass energy per nucleon pair of $\sqrt{s_{\mathrm{NN}}}=$ 5.02 TeV. The analysis is based on PbPb and pp data samples collected by CMS at the LHC in 2015, corresponding to integrated luminosities of 464 $\mu$b${}^{-1}$ and 28 pb${}^{-1}$, respectively. The measurements are performed in the dimuon rapidity range of $|y|<$ 2.4 as a function of centrality, rapidity, and transverse momentum (p${}_{\mathrm{T}}$) from p${}_{\mathrm{T}}=$ 3 GeV/$c$ in the most forward region and up to 50 GeV/$c$. Both prompt and nonprompt (coming from b hadron decays) mesons are observed to be increasingly suppressed with centrality, with a magnitude similar to the one observed at $\sqrt{s_{\mathrm{NN}}}=$ 2.76 TeV for the two J/$\psi$ meson components. No dependence on rapidity is observed for either prompt or nonprompt J/$\psi$ mesons. An indication of a lower prompt J/$\psi$ meson suppression at p${}_{\mathrm{T}}>$ 25 GeV/$c$ is seen with respect to that observed at intermediate p${}_{\mathrm{T}}$. The prompt $\psi$(2S) meson yield is found to be more suppressed than that of the prompt J/$\psi$ mesons in the entire p${}_{\mathrm{T}}$ range.

   nucl-exhep-exEPJC(2018)·197 citations
2. 02*

   Is it possible to study neutrinoless $\beta \beta$ decay by measuring double Gamow-Teller transitions?

   Javier Menéndez🇯🇵 · Noritaka Shimizu🇯🇵 · Kentaro Yako🇯🇵

   Searches of neutrinoless double-beta decay require information on the value of the nuclear matrix elements that rule the process to plan and interpret experiments. At present, however, even the matrix elements obtained with the most reliable many-body approaches do not agree to each other better than a factor two or three. A usual test of the many-body calculations is the comparison to several nuclear observables, but so far no nuclear structure property has been found to show a good correlation to neutrinoless double-beta decay. Here we propose that double charge-exchange experiments can offer a very valuable tool to provide insights on neutrinoless double-beta decay. Double charge-exchange reactions are being currently performed in various laboratories worldwide and aim to find the novel nuclear collectivity given by double Gamow-Teller excitations. Our results suggest a good linear correlation between double Gamow-Teller transitions to the ground state of the final nucleus and neutrinoless double-beta decay nuclear matrix elements. The correlation seems robust across $pf$-shell nuclei.

   ↳ nucl-thhep-exhep-phnucl-exJ.Phys.Conf.Ser.(2018)·8 citations
3. 03*

   Nucleon-to-Delta transition form factors in chiral effective field theory using the complex-mass scheme

   M. Hilt🇩🇪 · T. Bauer🇩🇪 · S. Scherer🇩🇪 · L. Tiator🇩🇪

   We calculate the form factors of the electromagnetic nucleon-to-$\Delta$-resonance transition to third chiral order in manifestly Lorentz-invariant chiral effective field theory. For the purpose of generating a systematic power counting, the complex-mass scheme is applied in combination with the small-scale expansion. We fit the results to available empirical data.

   ↳ nucl-thhep-phnucl-exPRC(2018)·19 citations
4. 04*

   Search For Gravitational Redshifted Absorption Lines In LMXB Serpens X-1

   Hiroki Yoneda · Chris Done · Frits Paerels · Tadayuki Takahashi · Shin Watanabe

   The equation of state for ultra-dense matter can be tested from observations of the ratio of mass to radius of neutron stars. This could be measured precisely from the redshift of a narrow line produced on the surface. X-rays bursts have been intensively searched for such features, but so far without detection. Here instead we search for redshifted lines in the persistent emission, where the accretion flow dominates over the surface emission. We discuss the requirements for narrow lines to be produced, and show that narrow absorption lines from highly ionized iron can potentially be observable in accreting low mass X-ray binaries (low B field) which have either low spin or low inclination so that Doppler broadening is small. This selects Serpens X-1 as the only potential candidate persistent LMXB due to its low inclination. Including surface models in the broad band accretion flow model predicts that the absorption line from He-like iron at 6.7 keV should be redshifted to $\sim$ 5.1 - 5.7 keV (10 - 15 km for $1.4{\mathrm{M}}_{\odot }$) and have an equivalent width of 0.8 - 8.0 eV for surface temperatures of 7 - 10 $\times$ 10${}^6$ K. We use the high resolution Chandra grating data to give a firm upper limit of 2 - 3 eV for an absorption line at $\sim 5$ keV. We discuss possible reasons for this lack of detection (the surface temperature and the geometry of the boundary layer etc.). Future instruments with better sensitivity are required in order to explore the existence of such features.

   ↳ astro-ph.HEnucl-exnucl-thMNRAS(2018)·1 citation

* 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.