Thu·Aug 12, 2021Thursday·August 12, 2021

1. 01*

   Measuring the light meson nuclear modification factor in p-Pb collisions over an unprecedented $p_{\text{T}}$ range with ALICE

   Joshua König (for the ALICE collaboration)🇩🇪

   Differential invariant cross sections of light neutral mesons in p-Pb collisions at $\sqrt{s_{\text{NN}}}$ = 8.16 TeV and in pp collisions at $\sqrt{s}$ = 8 TeV have been measured up to very high transverse momentum ($p_{\text{T}}$). By combining independent reconstruction techniques available in ALICE using the EMCal and PHOS calorimeters as well as the central barrel tracking detectors, the combined spectra cover almost two orders of magnitude in $p_{\mathrm{T}}$ for the ${\pi }^0$ meson. The nuclear modification factor $R_{\text{pPb}}$ has been measured for the ${\pi }^0$ and $\eta$ mesons and is found to be consistent with NLO pQCD, CGC and energy loss calculations. Comparisons to the $R_{\text{pPb}}$ of ${\pi }^0$ measured in $\sqrt{s_{\text{NN}}}$ = 5.02 TeV hint at a stronger suppression at low $p_{\mathrm{T}}$ with increasing collision energy.

   nucl-exhep-exSciPost Phys.Proc.(2022)·0 citations
2. 02*

   On the multipole mixing ratio of the 365 keV $\gamma$-transition in ${}^{129}$Ba

   S. Chakraborty🇮🇳

   The $E2/M1$ multipole mixing ratio ($\delta$), reported by J. Gizon et al. Phys. Rev. C 17, 596 (1978), for 365 keV $\gamma$-transition in ${}^{129}$Ba is reevaluated and found altered. Experimentally determined angular distribution coefficients indicate a large E2 admixture in the 365 keV $\gamma$-ray. Indeed, it is found in better agreement with the reported linear polarization value for this $\gamma$-ray.

   nucl-ex0 citations
3. 03*

   Pion charge radius from pion+electron elastic scattering data

   Zhu-Fang Cui🇨🇳 · Daniele Binosi🇮🇹 · Craig D. Roberts🇨🇳 · Sebastian M. Schmidt🇩🇪

   With the aim of extracting the pion charge radius, we analyse extant precise pion+electron elastic scattering data on $Q^2\in [0.015,0.144]$GeV${}^2$ using a method based on interpolation via continued fractions augmented by statistical sampling. The scheme avoids any assumptions on the form of function used for the representation of data and subsequent extrapolation onto $Q^2\simeq 0$. Combining results obtained from the two available data sets, we obtain $r_{\pi }=0.640(7)$fm, a value $2.4\sigma$ below today's commonly quoted average. The tension may be relieved by collection and similar analysis of new precise data that densely cover a domain which reaches well below $Q^2=0.015$GeV${}^2$. Considering available kaon+electron elastic scattering data sets, our analysis reveals that they contain insufficient information to extract an objective result for the charged-kaon radius, $r_K$. New data with much improved precision, low-$Q^2$ reach and coverage are necessary before a sound result for $r_K$ can be recorded.

   ↳ hep-phhep-exhep-latnucl-ex+1PLB(2021)·26 citations
4. 04*

   Final State Gluon Emission in Deep-Inelastic Scattering at Next-to-Leading Twist

   Chathuranga Sirimanna🇺🇸 · Shanshan Cao🇨🇳 · Abhijit Majumder🇺🇸

   A detailed reanalysis of the single gluon emission rate at next-to-leading twist is carried out. As was the case in prior efforts, the problem is cast in the framework of deep-inelastic scattering (DIS) of an electron off a large nucleus. The quark produced in the interaction propagates through the remaining nucleus and engenders scattering and gluon radiation, which is calculated in the limit of one re-scattering. This medium induced single gluon emission rate forms the basis of several energy loss calculations in both DIS and heavy-ion collisions. Unlike prior efforts, a complete transverse momentum gradient expansion of the hadronic tensor, including $N_c$ suppressed terms, phase terms and finite gluon momentum fraction terms, ignored previously, is carried out. These terms turn out to be surprisingly large. In contrast to prior efforts, the full next-to-leading twist gluon emission kernel is found to be positive definite and slowly increasing with the exchanged transverse momentum. Phenomenological consequences of these new contributions are discussed.

   ↳ hep-phnucl-exnucl-thPRC(2022)·19 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.