Wed·Sep 23, 2020Wednesday·September 23, 2020

1. 01*

   PRad-II: A New Upgraded High Precision Measurement of the Proton Charge Radius

   A. Gasparian · H. Gao · D. Dutta · N. Liyanage · E. Pasyuk · D. W. Higinbotham · C. Peng · K. Gnanvo · W. Xiong · X. Bai · the PRad collaboration

   The PRad experiment has credibly demonstrated the advantages of the calorimetric method in e-p scattering experiments to measure the proton root-mean-square (RMS) charge radius with high accuracy. The PRad result, within its experimental uncertainties, is in agreement with the small radius measured in muonic hydrogen spectroscopy experiments and it was a critical input in the recent revision of the CODATA recommendation for the proton charge radius. Consequently, the PRad result is in direct conflict with all modern electron scattering experiments. Most importantly, it is 5.8% smaller than the value from the most precise electron scattering experiment to date, and this difference is about three standard deviations given the precision of the PRad experiment. As the first experiment of its kind, PRad did not reach the highest precision allowed by the calorimetric technique. Here we propose a new (and) upgraded experiment -- PRad-II, which will reduce the overall experimental uncertainties by a factor of 3.8 compared to PRad and address this as yet unsettled controversy in subatomic physics. In addition, PRad-II will be the first lepton scattering experiment to reach the Q^2 range of 10^{-5} GeV^2 allowing a more accurate and robust extraction of the proton charge radius. The muonic hydrogen result with its unprecedented precision (~0.05%) determines the CODATA value of the proton charge radius, hence, it is critical to evaluate possible systematic uncertainties of those experiments, such as the laser frequency calibration that was raised in recent review articles. The PRad-II experiment with its projected total uncertainty of 0.43% could demonstrate whether there is any systematic difference between $e-p$ scattering and muonic hydrogen results. PRad-II will establish a new precision frontier in electron scattering and open doors for future physics opportunities.

   nucl-exhep-exnucl-th45 citations
2. 02*

   Analysis of Light Neutrino Exchange and Short-Range Mechanisms in $0\nu \beta \beta$ Decay

   Frank F. Deppisch🇬🇧 · Lukas Graf🇩🇪 · Francesco Iachello🇺🇸 · Jenni Kotila🇫🇮

   Neutrinoless double beta decay ($0\nu \beta \beta$) is a crucial test for lepton number violation. Observation of this process would have fundamental implications for neutrino physics, theories beyond the Standard Model and cosmology. Focussing on so called short-range operators of $0\nu \beta \beta$ and their potential interplay with the standard light Majorana neutrino exchange, we present the first complete calculation of the relevant nuclear matrix elements, performed within the interacting boson model (IBM-2). Furthermore, we calculate the relevant phase space factors using exact Dirac electron wavefunctions, taking into account the finite nuclear size and screening by the electron cloud. The obtained numerical results are presented together with up-to-date limits on the standard mass mechanism and effective $0\nu \beta \beta$ short-range operators in the IBM-2 framework. Finally, we interpret the limits in the particle physics scenarios incorporating heavy sterile neutrinos, Left-Right symmetry and R-parity violating supersymmetry.

   ↳ hep-phnucl-exnucl-thPRD(2020)·138 citations
3. 03*

   Ab-initio no-core shell model study of ${}^{10-14}$B isotopes with realistic NN interactions

   Priyanka Choudhary🇮🇳 · Praveen C. Srivastava🇮🇳 · Petr Navrátil🇨🇦

   We report a comprehensive study of ${}^{10-14}$B isotopes within the \textit{ab-initio} no-core shell model (NCSM) using realistic nucleon-nucleon (\textit{NN}) interactions. In particular, we have applied the inside non-local outside Yukawa (INOY) interaction to study energy spectra, electromagnetic properties and point-proton radii of the boron isotopes. The NCSM results with the charge-dependent Bonn 2000 (CDB2K), the chiral next-to-next-to-next-to-leading order (N${}^3$LO) and optimized next-to-next-to-leading order (N${}^2$LO${}_{opt}$) interactions are also reported. We have reached basis sizes up to $N_{\text{mbox}max}$ = 10 for ${}^{10}$B, $N_{\text{mbox}max}$ = 8 for ${}^{11,12,13}$B and $N_{\text{mbox}max}$ = 6 for ${}^{14}$B with m-scheme dimensions up to 1.7 billion. We also compare the NCSM calculations with the phenomenological YSOX interaction using the shell model to test the predictive power of the \textit{ab-initio} nuclear theory. Overall, our NCSM results are consistent with the available experimental data. The experimental ground state spin $3^{+}$ of ${}^{10}$B has been reproduced using the INOY \textit{NN} interaction. Typically, the 3\textit{N} interaction is required to correctly reproduce the aforementioned state.

   ↳ nucl-thnucl-exPRC(2020)·33 citations
4. 04*

   Pairing vibrations in the interacting boson model based on density functional theory

   K. Nomura🇭🇷 · D. Vretenar🇭🇷 · Z. P. Li · J. Xiang

   We propose a method to incorporate the coupling between shape and pairing collective degrees of freedom in the framework of the interacting boson model (IBM), based on the nuclear density functional theory. To account for pairing vibrations, a boson-number non-conserving IBM Hamiltonian is introduced. The Hamiltonian is constructed by using solutions of self-consistent mean-field calculations based on a universal energy density functional and pairing force, with constraints on the axially-symmetric quadrupole and pairing intrinsic deformations. By mapping the resulting quadrupole-pairing potential energy surface onto the expectation value of the bosonic Hamiltonian in the boson condensate state, the strength parameters of the boson Hamiltonian are determined. An illustrative calculation is performed for ${}^{122}$Xe, and the method is further explored in a more systematic study of rare-earth $N=92$ isotones. The inclusion of the dynamical pairing degree of freedom significantly lowers the energies of bands based on excited $0^{+}$ states. The results are in quantitative agreement with spectroscopic data, and are consistent with those obtained using the collective Hamiltonian approach.

   ↳ nucl-thnucl-exPRC(2020)·15 citations
5. 05*

   Neutral tritium gas reduction in the KATRIN differential pumping sections

   Alexander Marsteller🇩🇪 · Beate Bornschein🇩🇪 · Lutz Bornschein🇩🇪 · Guido Drexlin🇩🇪 · Fabian Friedel🇩🇪 · Rainer Gehring🇩🇪 · Steffen Grohmann🇩🇪 · Rainer Gumbsheimer🇩🇪 · Moritz Hackenjos🇩🇪 · Alexander Jansen🇩🇪 · Andreas Kosmider🇩🇪 · Luisa LaCascio🇩🇪 and 10 other authors

   The KArlsruhe TRItium Neutrino experiment (KATRIN) aims to measure the effective electron anti-neutrino mass with an unprecedented sensitivity of $0.2\mathrm{eV}/{\mathrm{c}}^2$, using $\beta$-electrons from tritium decay. The electrons are guided magnetically by a system of superconducting magnets through a vacuum beamline from the windowless gaseous tritium source through differential and cryogenic pumping sections to a high resolution spectrometer and a segmented silicon pin detector. At the same time tritium gas has to be prevented from entering the spectrometer. Therefore, the pumping sections have to reduce the tritium flow by more than 14 orders of magnitude. This paper describes the measurement of the reduction factor of the differential pumping section performed with high purity tritium gas during the first measurement campaigns of the KATRIN experiment. The reduction factor results are compared with previously performed simulations, as well as the stringent requirements of the KATRIN experiment.

   ↳ physics.ins-detastro-ph.IMnucl-exVacuum(2021)·25 citations
6. 06*

   Unfolding the Neutron Spectra from a Water-Pumping-Injection Multi-layered Concentric Sphere Neutron Spectrometer Using a Self-Adaptive Differential Evolution Algorithm

   Rui Li🇨🇳 · Jianbo Yang · Xianguo Tuo · Rui Shi🇨🇳 · Jie Xu

   A self-adaptive differential evolution neutron spectrum unfolding algorithm (SDENUA) was established in this paper to unfold the neutron spectra obtained from a Water-pumping-injection Multi-layered concentric sphere Neutron Spectrometer (WMNS). Specifically, the neutron fluence bounds were estimated to accelerate the algorithm convergence, the minimum error between the optimal solution and the input neutron counts with relative uncertainties was limited to 10-6 to avoid useless calculation. Furthermore, the crossover probability and scaling factor were controlled self-adaptively. FLUKA Monte Carlo was used to simulate the readings of the WMNS under (1) a spectrum of Cf-252 and (2) its spectrum after being moderated, (3) a spectrum used for BNCT, and (4) a reactor spectrum, and the measured neutron counts unfolded by using the SDENUA. The uncertainties of the measured neutron count and the response matrix are considered in the SDENUA, which does not require complex parameter tuning and the priori default spectrum. Results indicate that the solutions of the SDENUA are more in agreement with the IAEA spectra than that of the MAXED and GRAVEL in UMG 3.1, and the errors of the final results calculated by SDENUA are under 12%. The established SDENUA has potential applications for unfolding spectra from the WMNS.

   ↳ physics.ins-detnucl-exNucl.Sci.Tech.(2021)·0 citations
7. 07*

   Global analysis of the Sivers functions at NLO+NNLL in QCD

   Miguel G. Echevarria🇪🇸 · Zhong-Bo Kang🇺🇸 · John Terry🇺🇸

   We perform global fit to the quark Sivers function within the transverse momentum dependent (TMD) factorization formalism in QCD. We simultaneously fit Sivers asymmetry data from Semi-Inclusive Deep Inelastic Scattering (SIDIS) at COMPASS, HERMES, and JLab, from Drell-Yan lepton pair production at COMPASS, and from $W/Z$ boson at RHIC. This extraction is performed at next-to-leading order (NLO) and next-to-next-to leading logarithmic (NNLL) accuracy. We find excellent agreement between our extracted asymmetry and the experimental data for SIDIS and Drell-Yan lepton pair production, while tension arises when trying to describe the spin asymmetries of $W/Z$ bosons at RHIC. We carefully assess the situation, and we study in details the impact of the RHIC data and their implications through different ways of performing the fit. In addition, we find that the quality of the description of $W/Z$ vector boson asymmetry data could be strongly sensitive to the DGLAP evolution of Qiu-Sterman function, besides the usual TMD evolution. We present discussion on this and the implications for measurements of the transverse-spin asymmetries at the future Electron Ion Collider.

   ↳ hep-phhep-exnucl-exnucl-thJHEP(2021)·97 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.