Fri·Feb 4, 2022Friday·February 4, 2022

1. 01*

   Search for Spontaneous Radiation from Wavefunction Collapse in the Majorana Demonstrator

   I.J. Arnquist🇺🇸 · F.T. Avignone III🇺🇸 · A.S. Barabash🇷🇺 · C.J. Barton🇺🇸 · E. Blalock🇺🇸 · B. Bos🇺🇸 · M. Busch🇺🇸 · M. Buuck🇺🇸 · T.S. Caldwell🇺🇸 · Y-D. Chan🇺🇸 · C.D. Christofferson🇺🇸 · P.-H. Chu🇺🇸 and 42 other authors

   The Majorana Demonstrator neutrinoless double-beta decay experiment comprises a 44 kg (30 kg enriched in ${}^{76}\mathrm{Ge}$) array of $p$-type, point-contact germanium detectors. With its unprecedented energy resolution and ultralow backgrounds, Majorana also searches for rare event signatures from beyond standard model physics in the low energy region below 100 keV. In this Letter, we test the continuous spontaneous localization (CSL) model, one of the mathematically well-motivated wave function collapse models aimed at solving the long-standing unresolved quantum mechanical measurement problem. While the CSL predicts the existence of a detectable radiation signature in the x-ray domain, we find no evidence of such radiation in the 19--100 keV range in a 37.5 kg-y enriched germanium exposure collected between December 31, 2015, and November 27, 2019, with the Demonstrator. We explored both the non-mass-proportional (n-m-p) and the mass-proportional (m-p) versions of the CSL with two different assumptions: that only the quasifree electrons can emit the x-ray radiation and that the nucleus can coherently emit an amplified radiation. In all cases, we set the most stringent upper limit to date for the white CSL model on the collapse rate, $\lambda$, providing a factor of 40--100 improvement in sensitivity over comparable searches. Our limit is the most stringent for large parts of the allowed parameter space. If the result is interpreted in terms of the Diòsi-Penrose gravitational wave function collapse model, the lower bound with a 95% confidence level is almost an order of magnitude improvement over the previous best limit.

   nucl-exhep-exPRL(2022)·57 citations
2. 02*

   Multiplicity dependence of charged-particle jet production in pp collisions at $\sqrt{s}=13$ TeV

   ALICE Collaboration

   The multiplicity dependence of jet production in pp collisions at the centre-of-mass energy of $\sqrt{s}=13\mathrm{TeV}$ is studied for the first time. Jets are reconstructed from charged particles using the anti-$k_{\mathrm{T}}$ algorithm with resolution parameters $R$ varying from $0.2$ to $0.7$. The jets are measured in the pseudorapidity range $|{\eta }_{\mathrm{jet}}|<0.9-R$ and in the transverse momentum range $5<p_{\mathrm{T},\mathrm{jet}}^{\mathrm{ch}}<140\mathrm{GeV}/c$. The multiplicity intervals are categorised by the ALICE forward detector V0. The $p_{\mathrm{T}}$ differential cross section of charged-particle jets are compared to leading order (LO) and next-to-leading order (NLO) perturbative quantum chromodynamics (pQCD) calculations. It is found that the data are better described by the NLO calculation, although the NLO prediction overestimates the jet cross section below $20\mathrm{GeV}/c$. The cross section ratios for different $R$ are also measured and compared to model calculations. These measurements provide insights into the angular dependence of jet fragmentation. The jet yield increases with increasing self-normalised charged-particle multiplicity. This increase shows only a weak dependence on jet transverse momentum and resolution parameter at the highest multiplicity. While such behaviour is qualitatively described by the present version of PYTHIA, quantitative description may require implementing new mechanisms for multi-particle production in hadronic collisions.

   nucl-exhep-exEPJC(2022)·25 citations
3. 03*

   Measurement of of ${}^3\overline{\mathrm{He}}$ nuclei absorption in matter and impact on their propagation in the galaxy

   ALICE Collaboration

   In our Galaxy, light antinuclei composed of antiprotons and antineutrons can be produced through high-energy cosmic-ray collisions with the interstellar medium or could also originate from the annihilation of dark-matter particles that have not yet been discovered. On Earth, the only way to produce and study antinuclei with high precision is to create them at high-energy particle accelerators. Although the properties of elementary antiparticles have been studied in detail, the knowledge of the interaction of light antinuclei with matter is limited. We determine the disappearance probability of ${}^3\overline{\mathrm{He}}$ when it encounters matter particles and annihilates or disintegrates within the ALICE detector at the Large Hadron Collider. We extract the inelastic interaction cross section, which is then used as input to calculations of the transparency of our Galaxy to the propagation of ${}^3\overline{\mathrm{He}}$ stemming from dark-matter annihilation and cosmic-ray interactions within the interstellar medium. For a specific dark-matter profile, we estimate a transparency of about 50%, whereas it varies with increasing ${}^3\overline{\mathrm{He}}$ momentum from 25% to 90% for cosmic-ray sources. The results indicate that ${}^3\overline{\mathrm{He}}$ nuclei can travel long distances in the Galaxy, and can be used to study cosmic-ray interactions and dark-matter annihilation.

   nucl-exastro-ph.GAhep-exNat.Phys.(2023)·57 citations
4. 04*

   NCQ scaling of $f_0(980)$ elliptic flow in 200 GeV Au+Au collisions by STAR and its constituent quark content

   Jie Zhao (for the STAR collaboration)🇺🇸

   Searching for exotic state particles and studying their properties have furthered our understanding of quantum chromodynamics (QCD). The $f_0$(980) resonance is an exotic state with relatively high production rate in relativistic heavy-ion collisions, decaying primarily into $\pi \pi$. Currently, the structure and quark content of the $f_0$(980) are unknown with several predictions from theory being a $q\overline{q}$ state, a $qq\overline{q}\overline{q}$ state, a $K\overline{K}$ molecule state, or a gluonium state. We report the first $f_0$(980) elliptic flow ($v_2$) measurement from 200 GeV Au+Au collisions at STAR. The transverse momentum dependence of $v_2$ is examined and compared to those of other hadrons (baryons and mesons). The empirical number of constituent quark (NCQ) scaling is used to investigate the constituent quark content of $f_0$(980), which may potentially address an important question in QCD.

   nucl-exhep-exhep-phnucl-thEPJ Web Conf.(2022)·1 citation
5. 05*

   On the possibility of a significant increase in the storage time of ultracold neutrons in traps coated with a liquid helium film

   P.D. Grigoriev · A. M. Dyugaev · T.I. Mogilyuk · A.D. Grigoriev

   It is shown that rough inner walls of a trap of ultracold neutrons can be coated with a superfluid helium film much thicker than the depth of penetration of ultracold neutrons into helium. This coating should reduce the rate of loss of ultracold neutrons caused by absorption in the walls of the trap by orders of magnitude. It is demonstrated that triangular roughness is more efficient than rectangular for the reduction of the rate of loss of ultracold neutrons. Triangular roughness is more easily implemented technically and such diffraction gratings are fabricated industrially. Other methods are proposed to increase the thickness of the protective helium film.

   ↳ cond-mat.othernucl-exJETP Lett.(2021)·4 citations
6. 06*

   Neutrino Astronomy with IMB, Kamiokande and Super Kamiokande

   John M. LoSecco🇺🇸

   Some of the earliest work on neutrino astronomy was accomplished by a class of underground detectors primarily designed for particle physics goals . These detectors used inexpensive water to obtain the large masses needed to observe the very low interaction rates expected from neutrinos. They exploited the relatively large light attenuation length and the index of refraction of the water to get a very inexpensive cost per thousand tons of detector. The results obtained from these pioneering neutrino detectors have included real time observation of solar neutrinos, supernova neutrinos, and atmospheric neutrinos. Searches for neutrino point sources, dark matter and primordial magnetic monopoles were also made using them.

   ↳ astro-ph.HEhep-exhep-thnucl-ex+10 citations
7. 07*

   Toward the discovery of matter creation with neutrinoless double-beta decay

   Matteo Agostini🇬🇧 · Giovanni Benato🇮🇹 · Jason A. Detwiler🇺🇸 · Javier Menéndez🇪🇸 · Francesco Vissani🇮🇹

   The discovery of neutrinoless double-beta decay could soon be within reach. This hypothetical ultra-rare nuclear decay offers a privileged portal to physics beyond the Standard Model of particle physics. Its observation would constitute the discovery of a matter-creating process, corroborating leading theories of why the universe contains more matter than antimatter, and how forces unify at high energy scales. It would also prove that neutrinos and anti-neutrinos are not two distinct particles, but can transform into each other, with their mass described by a unique mechanism conceived by Majorana. The recognition that neutrinos are not massless necessitates an explanation and has boosted interest in neutrinoless double-beta decay. The field stands now at a turning point. A new round of experiments is currently being prepared for the next decade to cover an important region of parameter space. In parallel, advances in nuclear theory are laying the groundwork to connect the nuclear decay with the underlying new physics. Meanwhile, the particle theory landscape continues to find new motivations for neutrinos to be their own antiparticle. This review brings together the experimental, nuclear theory, and particle theory aspects connected to neutrinoless double-beta decay, to explore the path toward - and beyond - its discovery.

   ↳ hep-exhep-phhep-thnucl-ex+1RMP(2023)·433 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.