Tue·Jan 23, 2024Tuesday·January 23, 2024

1. 01*

   Heavy Flavor Physics at the sPHENIX Experiment

   Zhaozhong Shi (on behalf of the sPHENIX collaboration)🇺🇸

   The sPHENIX experiment is a state-of-the-art jet and heavy flavor physics detector which successfully recorded its first Au + Au collision data at 200 GeV at RHIC. sPHENIX will provide heavy flavor physics measurements covering an unexplored kinematic region and unprecedented precision at RHIC to probe the parton energy loss mechanism, parton transport coefficients in quark-gluon plasma, and the hadronization process under various medium conditions. At the center of sPHENIX, the Monolithic-Active-Pixel-Sensor (MAPS) based VerTeX detector (MVTX) is a high-precision silicon pixel detector. The MVTX provides excellent position resolution and the capability of operating in continuous streaming readout mode, allowing precise vertex determination and recording a large data sample, both of which are particularly crucial for heavy flavor physics measurements. In this work, we will show the general performance of heavy-flavor hadron reconstruction. In addition, we will discuss the commissioning experience with sPHENIX. Finally, we will provide the projection of b-hadron and jet observables and discuss the estimated constraints on theoretical models.

   nucl-exUniverse(2024)·5 citations
2. 02*

   A survey of nuclear quadrupole deformation in order to estimate the nuclear MQM and its relative contribution to the atomic EDM

   Prajwal MohanMurthy🇺🇸 · Umesh Silwal🇺🇸 · Jeff A. Winger🇺🇸

   New sources of charge-parity (CP) violation, beyond the known sources in the standard model (SM), are required to explain the baryon asymmetry of the universe. Measurement of a non-zero permanent electric dipole moment (EDM) in fundamental particles, such as in an electron or a neutron, or in nuclei or atoms, can help us gain a handle on the sources of CP violation, both in the SM and beyond. The nuclear magnetic quadrupole moment (MQM), the central topic of this work, is also CP, P, and T violating. Nucleons and nuclei have a non-zero MQM from sources within the SM, but the nuclear MQM is dramatically enhanced if the nuclei are structurally quadrupole deformed. Multiple sources contribute to an atomic EDM \emph{viz.} (i) nuclear EDM through its Schiff moment, which is enhanced by nuclear octupole deformation, (ii) CP violating interactions between the electrons and the nuclei, and (iii) the nuclear MQM that contributes to the atomic EDM in atoms with an unpaired valence electron. Our survey of nuclear quadrupole deformation has identified ${}^{151}$Nd, ${}^{153}$Pm, ${}^{153}$Sm, ${}^{157}$Ho, ${}^{163,165}$Er, ${}^{161,168}$Tm, ${}^{167}$Yb, ${}^{169}$Hf, ${}^{171,180}$Ta, ${}^{173,175,177,179,180}$Re, ${}^{190,192}$Ir, ${}^{188}$Au, ${}^{223,225}$Fr, ${}^{223,227,229,231}$Ra, ${}^{223,225,227,229}$Ac, ${}^{229,231}$Th, ${}^{229,231,233,235}$Pa, ${}^{235}$U, ${}^{233,235,237,238,239}$Np, ${}^{237}$Pu, and ${}^{239,241,242,243,245}$Am as ideal systems in which to search for a CP violating EDM via their enhanced nuclear MQM, while ${}^{223,225}$Fr, ${}^{223}$Ra, ${}^{223,225,227}$Ac, ${}^{229}$Th, and ${}^{229}$Pa also have maximally enhanced nuclear Schiff moment contribution due to their octupole deformation. Laser cooling of the isotopes of Er, Tm, Yb, Fr, and Ra has already been demonstrated, making ${}^{223,225}$Fr and ${}^{223}$Ra some of the best systems in which to measure an EDM.

   nucl-exHyperfine Interact.(2024)·1 citation
3. 03*

   Pion interferometry with Lévy-stable sources in $\sqrt{s_{NN}}$ = 200 GeV Au+Au collisions at STAR

   Dániel Kincses (for the STAR Collaboration)🇭🇺

   Measurements of femtoscopic correlations in high-energy heavy-ion collisions aim to unravel the space-time structure of the particle-emitting source (the quark-gluon plasma). Recent results indicate that the pion pair source exhibits a power-law behavior and can be described well by a Lévy distribution. In this study, Lévy fits were performed to the measured one-dimensional two-pion correlation functions in Au+Au collisions at $\sqrt{s_{NN}}$=200 GeV. The three extracted source parameters are the Lévy scale parameter, $R$, which relates to the size of the source; the correlation strength parameter, $\lambda$; and the Lévy exponent, $\alpha$, which characterizes the power-law tail of the source. In this paper, we report the current status of the analysis of the extracted Lévy source parameters and present their dependence on average transverse mass, $m_T$, and on centrality.

   nucl-exUniverse(2024)·17 citations
4. 04*

   Checking the ${}^8$Be anomaly with a two-arm electron positron pair spectrometer

   Tran The Anh · Tran Dinh Trong · Attila J. Krasznahorkay🇭🇺 · Attila Krasznahorkay🇭🇺 · József Molnár · Zoltán Pintye · Nguyen Ai Viet🇻🇳 · Nguyen The Nghia · Do Thi Khanh Linh · Bui Thi Hoa · Le Xuan Chung · Nguyen Tuan Anh

   We have repeated the experiment performed recently by Krasznahorkay et al., (Phys. Rev. Lett. 116, 042501 (2016)), which may indicate a new particle called X17 in the literature. In order to get a reliable, and independent result, we used a different type of electron-positron pair spectrometer which have a more simple acceptance/efficiency as a function of the correlation angle, but the other conditions of the experiment were very similar to the published ones. We could confirm the presence of the anomaly measured at the E${}_x$=18.15 MeV resonance, and also confirm their absence at the E${}_x$=17.6 MeV resonance, and at E${}_p$= 800 keV off resonance energies.

   nucl-exphysics.ins-detUniverse(2024)·29 citations
5. 05*

   Study of the hadron gas phase using short-lived resonances with ALICE

   Johanna Lömker (for the ALICE Collaboration)🇳🇱

   Short-lived hadronic resonances are unique tools for studying the hadron-gas phase that is created in the late stages of relativistic heavy-ion collisions. Measurements of the yield ratios between resonances and the corresponding stable particles are sensitive to the competing rescattering and regeneration effects. These measurements in small collision systems, such as pp and p-Pb, are a powerful method to reveal a possible short-lived hadronic phase. In addition, resonance production in small systems is interesting to study the onset of strangeness enhancement, collective effects,and the hadron production mechanism. On this front, the $\varphi$ meson is particularly relevant since its yield is sensitive to different production models: no effect is expected by strange number canonical suppression but its production is expected to be enhanced in the rope-hadronization scenario. In this presentation, recent measurements of hadronic resonances in different collision systems,going from pp to Pb-Pb collisions, are presented. These include transverse momentum spectra,yields, and yield ratios as a function of multiplicity. The presented results are discussed in the context of state-of-the-art phenomenological models of hadron production. The resonance yields measured in Pb-Pb collisions are used as an experimental input in a partial chemical equilibrium-based thermal model to constrain the kinetic freeze-out temperature. This is a novel procedure that is independent of assumptions on the flow velocity profile and the freeze-out hypersurface.

   nucl-exhep-exPoS(2024)·1 citation
6. 06*

   Prompt and nonprompt $\psi (2S)$ production in $p$Pb collisions at $\sqrt{s_{NN}}=8.16$ TeV

   LHCb collaboration: R. Aaij · A.S.W. Abdelmotteleb · C. Abellan Beteta · F. Abudinén · T. Ackernley · B. Adeva · M. Adinolfi · P. Adlarson · H. Afsharnia · C. Agapopoulou · C.A. Aidala · Z. Ajaltouni and 1091 other authors

   The production of $\psi (2S)$ mesons in proton-lead collisions at a centre-of-mass energy per nucleon pair of $\sqrt{s_{NN}}=8.16$ TeV is studied with the LHCb detector using data corresponding to an integrated luminosity of 34 nb${}^{-1}$. The prompt and nonprompt $\psi (2S)$ production cross-sections and the ratio of the $\psi (2S)$ to $J/\psi$ cross-section are measured as a function of the meson transverse momentum and rapidity in the nucleon-nucleon centre-of-mass frame, together with forward-to-backward ratios and nuclear modification factors. The production of prompt $\psi (2S)$ is observed to be more suppressed compared to $pp$ collisions than the prompt $J/\psi$ production, while the nonprompt productions have similar suppression factors.

   ↳ hep-exnucl-exJHEP(2024)·23 citations
7. 07*

   Tensor force impact on shell evolution in neutron-rich Si and Ni isotopes

   S.V. Sidorov · A.S. Kornilova · T.Yu. Tretyakova

   The influence of the tensor interaction of nucleons on the characteristics of neutron-rich silicon and nickel isotopes was studied in this work. Tensor forces are taken into account within the framework of the Hartree-Fock approach with the Skyrme interaction. It is shown that the addition of tensor component of interaction improves the description of the splitting between different single-particle states and leads to a decrease in nucleon-nucleon pairing correlations in silicon and nickel nuclei. Special attention was given to the role of isovector tensor forces relevant for interaction of like nucleons.

   ↳ nucl-thnucl-exCPC(2024)·0 citations
8. 08*

   Pion-production cross sections in neutrino reactions for studying generalized parton distributions of the nucleon

   Xurong Chen🇨🇳 · S. Kumano🇨🇳 · R. Kunitomo🇯🇵 · Siyu Wu🇨🇳 · Ya-Ping Xie🇨🇳

   Gravitational form factors of hadrons provide information on mass and pressure distributions in the hadrons, and they have been investigated by generalized parton distributions (GPDs). The GPDs also contain information on internal compositions of hadron spins. Understanding on the origin of hadron masses, pressures, and spins is an important topic not only in hadron physics but also as fundamental physics, and it should be clarified by the GPD studies. The spacelike and timelike GPDs have been measured at charged-lepton accelerator facilities, for example, by the virtual Compton scattering and the two-photon process, respectively. In this work, we show the ${\pi }^{\pm }$ and ${\pi }^0$ production cross sections in neutrino (antineutrino) reactions $\nu (\bar{\nu })+N\to \ell +\pi +N^{\prime }$ for measuring the GPDs of the nucleon by using the theoretical formalism of Pire, Szymanowski, and Wagner. The ${\pi }^{\pm }$-production cross sections are useful for determining gluon GPDs, whereas the ${\pi }^0$ production probes quark GPDs. In particular, we show the roles of the pion- and rho-pole terms, the contribution from each GPD term ($H$, $E$, $\tilde{H}$, $\tilde{E}$), the effects of the gluon GPDs $H_g$ and $E_g$, and the effects of the reaction energy on the neutrino cross sections. The ${\pi }^0$-production cross section is sensitive to the quark GPDs including the pion- and rho-pole GPD terms in the Efremov-Radyushkin-Brodsky-Lepage region. These cross sections could be measured at Fermilab in future. The neutrino GPD studies will play a complementary role to the projects of charged-lepton and hadron reactions for determining the accurate GPDs.

   ↳ hep-phhep-exhep-latnucl-exEPJA(2024)·6 citations
9. 09*

   Weakening of $N=28$ shell gap and the nature of $0_2^{+}$ states

   Bhoomika Maheshwari🇫🇷 · Kosuke Nomura🇯🇵

   The work reports a novel application of the interacting boson model in light-mass region around ${}^{48}$Ca, that takes into account intruder states and configuration mixing. The model is shown to provide a reasonable description of the observed low-lying yrast and yrare states of the $N=28$ even-even isotones from Si to Fe, and even-even Ca isotopes. The nature of $0_2^{+}$ states is addressed in terms of the competition between spherical and deformed intruder configurations, and the rigidity of the $N=28$ shell gap is tested. The $0_2^{+}$ isomer in ${}^{44}$S is shown to arise from a weak mixing between the two configurations. The unresolved low-lying spectra in ${}^{46}$Ar is also approached using the core-excitations across $N=28$ shell. The SU(3) structure in ${}^{42}$Si is supported by the present calculation. The nearly spherical nature of ${}^{50}$Ti, ${}^{52}$Cr, ${}^{54}$Fe and ${}^{42,44,46}$Ca isotopes is found, while the core excitations are found to be essential for the description of yrare states. Shell model calculation is also performed for comparison.

   ↳ nucl-thnucl-exJ.Phys.G(2024)·4 citations
10. 10*

    Discrete symmetries tested at 10${}^{-4}$ precision using linear polarization of photons from positronium annihilations

    Paweł Moskal🇵🇱 · Eryk Czerwiński🇵🇱 · Juhi Raj🇵🇱 · Steven D. Bass🇵🇱 · Ermias Y. Beyene🇵🇱 · Neha Chug🇵🇱 · Aurélien Coussat🇵🇱 · Catalina Curceanu🇮🇹 · Meysam Dadgar🇵🇱 · Manish Das🇵🇱 · Kamil Dulski🇮🇹 · Aleksander Gajos🇵🇱 and 29 other authors

    Discrete symmetries play an important role in particle physics with violation of CP connected to the matter-antimatter imbalance in the Universe. We report the most precise test of P, T and CP invariance in decays of ortho-positronium, performed with methodology involving polarization of photons from these decays. Positronium, the simplest bound state of an electron and positron, is of recent interest with discrepancies reported between measured hyperfine energy structure and theory at the level of $10^{-4}$ signaling a need for better understanding of the positronium system at this level. We test discrete symmetries using photon polarizations determined via Compton scattering in the dedicated J-PET tomograph on an event-by-event basis and without the need to control the spin of the positronium with an external magnetic field, in contrast to previous experiments. Our result is consistent with QED expectations at the level of 0.0007 and one standard deviation.

    ↳ hep-phnucl-exNature Commun.(2024)·37 citations
11. 11*

    Femtoscopy between $\pi$, $K$ and $p$ in different heavy-ion collisions at $\sqrt{s_{NN}}$ = 39 GeV

    Ting-Ting Wang🇨🇳 · Yu-Gang Ma🇨🇳 · Song Zhang🇨🇳

    Momentum correlation functions between $\pi$, $K$ and $p$ are calculated for several heavy-ion collision systems, namely ${}_5^{10}\text{B}{+}_5^{10}\text{B}$, ${}_8^{16}\text{O}{+}_8^{16}\text{O}$, ${}_{20}^{40}\text{Ca}{+}_{20}^{40}\text{Ca}$ and ${}_{79}^{197}\text{Au}{+}_{79}^{197}\text{Au}$ in central collisions as well as ${}_{79}^{197}\text{Au}{+}_{79}^{197}\text{Au}$ collision in different centralities at center of mass energy $\sqrt{s_{NN}}$ = 39 GeV within the framework of A Multi-Phase Transport (AMPT) model complemented by the Lednick$\acute{y}$ and Lyuboshitz analytical method. The results present the centrality and system-size dependence of the momentum correlation functions among pairs of $\pi$, $K$ and $p$, from which the emission source-size can be deduced. It is found that the deduced source sizes increase with the decreasing of centrality for Au + Au system or with the increasing of system-size in central collisions with different nuclear size. In addition, through the momentum correlation functions of nonidentical particle pairs gated on velocity, the average emission sequence of non-identical particles can be indicated. The results illustrate that in the small relative momentum region, protons are emitted in average earlier than ${\pi }^{+}$ and $K^{+}$, and $K^{+}$ are emitted averagely earlier than ${\pi }^{+}$. Furthermore, it seems that larger interval of the average emission order among them is exhibited for smaller collision systems. The present study sheds light on the dynamics of light particle emission at RHIC energy.

    ↳ hep-phnucl-exnucl-th1 citation

* 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.