Fri·May 5, 2023Friday·May 5, 2023

1. 01*

   Collapse of the $N=28$ shell closure in the newly discovered ${}^{39}$Na and the development of deformed halos towards the neutron dripline

   K. Y. Zhang🇨🇳 · P. Papakonstantinou🇰🇷 · M.-H. Mun🇰🇷 · Y. Kim🇰🇷 · H. Yan🇨🇳 · X.-X. Sun🇨🇳

   Halos and changes of nuclear magicities have been extensively investigated in exotic nuclei during past decades. The newly discovered ${}^{39}$Na with the neutron number $N=28$ provides a new platform to explore such novel phenomena near the neutron dripline of the sodium isotopic chain. We study the shell property and the possible halo structure in ${}^{39}$Na within the deformed relativistic Hartree-Bogoliubov theory in continuum. It is found that the lowering of $2p$ orbitals in the spherical limit results in the collapse of the $N=28$ shell closure in ${}^{39}$Na, and a well deformed ground state is established. The pairing correlations and the mixing of $pf$ components driven by deformation lead to the occupation of weakly bound or continuum $p$-wave neutron orbitals. An oblate halo is therefore formed around the prolate core in ${}^{39,41}$Na, making ${}^{39}$Na a single nucleus with the coexistence of several exotic structures, including the quenched $N=28$ shell closure, Borromean structure, deformed halo, and shape decoupling. The microscopic mechanisms behind the shape decoupling phenomenon and the development of halos towards dripline are revealed.

   ↳ nucl-thnucl-exPRC(2023)·58 citations
2. 02*

   Probing the onset of maximal entanglement inside the proton in diffractive DIS

   Martin Hentschinski🇲🇽 · Dmitri E. Kharzeev🇺🇸 · Krzysztof Kutak🇵🇱 · Zhoudunming Tu🇺🇸

   It has been proposed that at small Bjorken $x$, or equivalently at high energy, hadrons represent maximally entangled states of quarks and gluons. This conjecture is in accord with experimental data from the electron-proton collider HERA at the smallest accessible $x$. In this Letter, we propose to study the onset of the maximal entanglement inside the proton using Diffractive Deep Inelastic Scattering. It is shown that the data collected by the H1 Collaboration at HERA allows to probe the transition to the maximal entanglement regime. By relating the entanglement entropy to the entropy of final state hadrons, we find a good agreement with the H1 data using both the exact entropy formula as well as its asymptotic expansion which indicates the presence of a nearly maximally-entangled state. Finally, future opportunities at the Electron Ion Collider are discussed.

   ↳ hep-phhep-exnucl-exnucl-th+1PRL(2023)·52 citations
3. 03*

   Minimal model for the $W$-boson mass, $(g-2{)}_{\mu }$, $h\to {\mu }^{+}{\mu }^{-}$ and quark-mixing-matrix unitarity

   Andreas Crivellin🇨🇭 · Matthew Kirk🇪🇸 · Anil Thapa🇺🇸

   The $SU(2{)}_L$ triplet scalar with hypercharge $Y=0$ predicts a positive definite shift in the $W$ mass, w.r.t.~the Standard Model prediction, if it acquires a vacuum expectation value. As this new field cannot couple directly to SM fermions (on its own), it has no significant impact on other low-energy precision observables and is weakly constrained by collider searches. In fact, the multi-lepton anomalies at the LHC even point towards new scalars that decay dominantly to $W$ bosons, as the neutral component of the triplet naturally does. In this article, we show that with a minimal extension of the scalar triplet model by a heavy vector-like lepton, being either I) an $SU(2{)}_L$ doublet with $Y=-1/2$ or II) an $SU(2{)}_L$ triplet with $Y=-1$, couplings of the triplet to Standard Model leptons are possible. This minimal extension can then provide, in addition to the desired positive shift in the $W$ mass, a chirally enhanced contribution to $(g-2{)}_{\mu }$. In addition version I) and II) can improve on $Z\to {\mu }^{+}{\mu }^{-}$ and alleviate the tension in first-row CKM unitarity (known as the Cabibbo angle anomaly), respectively. Finally, both options, in general, predict sizable changes of $h\to {\mu }^{+}{\mu }^{-}$, i.e.,~much larger than most other $(g-2{)}_{\mu }$ explanations where only $O(\%)$ effects are expected, making this channel a smoking gun signature of our model.

   ↳ hep-phhep-exhep-latnucl-ex+1PRD(2023)·17 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.