Fri·Dec 18, 2020Friday·December 18, 2020

1. 01*

   Study of the strong interaction among hadrons with correlations at the LHC

   L. Fabbietti🇩🇪 · V. Mantovani Sarti🇩🇪 · O. Vazquez Doce🇩🇪

   The strong interaction among hadrons has been measured in the past by scattering experiments. Although this technique has been extremely successful in providing information about the nucleon-nucleon and pion-nucleon interactions, when unstable hadrons are considered the experiments become more challenging. In the last few years, the analysis of correlations in the momentum space for pairs of stable and unstable hadrons measured in pp and p-Pb collisions by the ALICE Collaboration at the LHC has provided a new method to investigate the strong interaction among hadrons. In this article, we review the numerous results recently achieved for hyperon-nucleon, hyperon-hyperon, and kaon-nucleon pairs, which show that this new method opens the possibility of measuring the residual strong interaction of any hadron pair.

   nucl-exAnn.Rev.Nucl.Part.Sci.(2021)·186 citations
2. 02*

   On the $\beta$-decay of ${}^{186}$Hg

   A. Algora🇪🇸 · E. Ganioğlu🇹🇷 · P. Sarriguren🇪🇸 · V.Guadilla🇪🇸 · L. M. Fraile🇪🇸 · E. Nácher🇪🇸 · B. Rubio🇪🇸 · J. L. Tain🇪🇸 · J. Agramunt🇪🇸 · W. Gelletly🇬🇧 · J. A. Briz🇪🇸 · R. B. Cakirli🇹🇷 and 11 other authors

   The Gamow-Teller strength distribution of the decay of ${}^{186}$Hg into ${}^{186}$Au has been determined for the first time using the total absorption gamma spectroscopy technique and has been compared with theoretical QRPA calculations using the SLy4 Skyrme force. The measured Gamow-Teller strength distribution and the half-life are described by mixing oblate and prolate configurations independently in the parent and daughter nuclei. The best description of the experimental beta strength is obtained with dominantly prolate components for both parent ${}^{186}$Hg and daughter ${}^{186}$Au. The approach also allowed us to determine an upper limit of the oblate component in the parent state. The complexity of the analysis required the development of a new approach in the analysis of the X-ray gated total absorption spectrum.

   nucl-exnucl-thPLB(2021)·11 citations
3. 03*

   Search for Light Exotic Fermions in Double-Beta Decays

   Matteo Agostini🇬🇧 · Elisabetta Bossio🇩🇪 · Alejandro Ibarra🇩🇪 · Xabier Marcano🇩🇪

   The Standard Model of Particle Physics predicts the double-$\beta$ decay of certain nuclei with the emission of two active neutrinos. In this letter, we argue that double-$\beta$ decay experiments could be used to probe models with light exotic fermions through the search for spectral distortions in the electron spectrum with respect to the Standard Model expectations. We consider two concrete examples: models with light sterile neutrinos, singly produced in the double-$\beta$ decay, and models with a light $Z_2$-odd fermion, pair produced due to a $Z_2$ symmetry. We estimate the discovery potential of a selection of double-$\beta$ decay experiments and find that future searches will test for the first time a new part of the parameter space of interest at the MeV-mass scale.

   ↳ hep-phhep-exnucl-exPLB(2021)·22 citations
4. 04*

   Nuclear clocks for testing fundamental physics

   E. Peik🇩🇪 · T. Schumm🇦🇹 · M. S. Safronova🇺🇸 · A. Pálffy🇩🇪 · J. Weitenberg🇩🇪 · P. G. Thirolf🇩🇪

   The low-energy, long-lived isomer in ${}^{229}$Th, first studied in the 1970s as an exotic feature in nuclear physics, continues to inspire a multidisciplinary community of physicists. Using the nuclear resonance frequency, determined by the strong and electromagnetic interactions inside the nucleus, it is possible to build a highly precise nuclear clock that will be fundamentally different from all other atomic clocks based on resonant frequencies of the electron shell. The nuclear clock will open opportunities for highly sensitive tests of fundamental principles of physics, particularly in searches for violations of Einstein's equivalence principle and for new particles and interactions beyond the standard model. It has been proposed to use the nuclear clock to search for variations of the electromagnetic and strong coupling constants and for dark matter searches. The ${}^{229}$Th nuclear optical clock still represents a major challenge in view of the tremendous gap of nearly 17 orders of magnitude between the present uncertainty in the nuclear transition frequency and the natural linewidth. Significant experimental progress has been achieved in recent years, which will be briefly reviewed. Moreover, a research strategy will be outlined to consolidate our present knowledge about essential ${}^{229\mathrm{m}}$Th properties, to determine the nuclear transition frequency with laser spectroscopic precision, realize different types of nuclear clocks and apply them in precision frequency comparisons with optical atomic clocks to test fundamental physics. Two avenues will be discussed: laser-cooled trapped ${}^{229}$Th ions that allow experiments with complete control on the nucleus-electron interaction and minimal systematic frequency shifts, and Th-doped solids enabling experiments at high particle number and in different electronic environments.

   ↳ quant-phnucl-exphysics.atom-phphysics.opticsQuantum Sci.Technol.(2021)·132 citations
5. 05*

   Probing the boundary of phase transition of nuclear matter using proton flows in heavy-ion collisions at 2-8 GeV/nucleon

   Ya-Fei Guo🇨🇳 · Gao-Chan Yong🇨🇳

   Based on the relativistic transport model ART with the hadronic equation of state extended to have a phase transition via the use of the MIT bag model, properties of phase transition of dense nuclear matter formed in relativistic heavy-ion collisions are investigated. Proton sideward and directed flows are calculated with different equation of states in Au + Au collisions at beam energies of 2, 4, 6 and 8 GeV/nucleon. Compared with AGS experimental data in existence, the boundary of first-order phase transition is roughly confined, i.e., in the range of 2.5-4 times saturation density with temperature about 64-94 MeV. Such constraints are useful for ongoing RHIC Beam Energy Scan-II program to study the QCD matter phase diagram.

   ↳ nucl-thnucl-exPLB(2021)·8 citations
6. 06*

   Searching for Lepton Flavour (Universality) Violation and Collider Signals from a Singly-Charged Scalar Singlet

   Andreas Crivellin🇨🇭 · Fiona Kirk🇨🇭 · Claudio Andrea Manzari🇨🇭 · Luca Panizzi🇸🇪

   In recent years, evidence for lepton flavour universality violation beyond the Standard Model has been accumulated. In this context, a singly charged $SU(2{)}_L$ singlet scalar (${\varphi }^{\pm }$) is very interesting, as it can only have flavour off-diagonal couplings to neutrinos and charged leptons, therefore necessarily violating lepton flavour (universality). In fact, it gives a (necessarily constructive) tree-level effect in $\ell \to {\ell }^{\prime }\nu \nu$ processes, while contributing to charged lepton flavour violating only at the loop-level. Therefore, it can provide a common explanation of the hints for new physics in $\tau \to \mu \nu \nu /\tau (\mu )\to e\nu \nu$ and of the Cabibbo Angle Anomaly. Such an explanation predicts $\mathrm{Br}[\tau \to e\gamma ]$ to be of the order of a few times $10^{-11}$ while $\mathrm{Br}[\tau \to e\mu \mu ]$ can be of the order of $10^{-9}$ for order one couplings and therefore in the reach of forthcoming experiments. Furthermore, we derive a {novel} coupling-independent lower limit on the scalar mass of $\approx 200$GeV by recasting LHC slepton searches. In the scenario preferred by low energy precision data, the lower limit is even strengthened to $\approx 300$GeV, showing the complementary between LHC searches and flavour observables. Furthermore, we point out that this model can be tested by reinterpreting DM mono-photon searches at future $e^{+}{e}^{-}$ colliders.

   ↳ hep-phhep-exnucl-exnucl-thPRD(2021)·66 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.