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1. Spin dependence of meson thresholds in the diabatic dynamical diquark model

   https://doi.org/10.1103/4sx7-rrdl  

   Lebed, Richard F (December 2025, Physical Review D)

   The diabatic dynamical diquark model is designed to unify diquark and molecular approaches for exotic hadrons by including the effects of dimeson thresholds on fundamental diquark-antidiquark states in order to form physical tetraquarks. We generalize this model by implementing the consequences of heavy-quark spin symmetry for each dimeson pair. We include the specific spin factors and mass differences associated with mesons related by this symmetry (such as $D,D^{*}$ ), both features being necessary for the systematic incorporation of effects beyond the static, heavy-source limit inherent to the (adiabatic) Born-Oppenheimer treatment. We obtain explicit interaction potentials for all $J=0$ , 1, 2 states, along the way deriving unusual variants of Fierz reordering identities, and discuss the application of the potentials to specific physical states such as ${\chi }_{c1}\left(3872\right)$ and $T_{c\overline{c}1}\left(3900\right)$ . 

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2. Diabatic dynamical diquark model of hidden-strangeness tetraquarks

   https://doi.org/10.1103/vspf-jybk  

   Jafarzade, Shahriyar; Lebed, Richard F (December 2025, Physical Review D)

   We generalize our recent analysis of hidden-strangeness tetraquarks within the dynamical diquark model from its adiabatic form (in which each state is described solely by a diquark-antidiquark potential) to its diabatic form (which incorporates effects of dihadron thresholds upon the states). We tabulate all relevant thresholds and compute the dihadron content of each predicted state. Our results produce no particular hidden-strange tetraquark candidate whose structure is dominated by dihadron structure, in contrast to the charm sector, where many exotic states are strongly associated with such thresholds: The hidden-strange states tend to remain compact and less influenced by dihadron thresholds. Multiple states above 2 GeV with peculiar decay properties, including $\varphi \left(2170\right)$ , $f_2\left(2340\right)$ , and $\eta \left(2370\right)$ , continue to serve as excellent hidden-strange tetraquark candidates. 

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3. Measurements of $\mathrm{\Upsilon }$ states production in $p+p$ collisions at $\sqrt{s}=500\mathrm{GeV}$ with STAR: Cross sections, ratios, and multiplicity dependence

   https://doi.org/10.1103/bsyx-qtjp  

   Aboona, B E; Adam, J; Adamczyk, L; Aggarwal, I; Aggarwal, M M; Ahammed, Z; Alshammri, A K; Aschenauer, E C; Aslam, S; Atchison, J; et al (August 2025, Physical Review D)

   We report measurements of $\mathrm{\Upsilon }\left(1S\right)$ , $\mathrm{\Upsilon }\left(2S\right)$ and $\mathrm{\Upsilon }\left(3S\right)$ production in $p+p$ collisions at $\sqrt{s}=500\mathrm{GeV}$ by the STAR experiment in year 2011, corresponding to an integrated luminosity ${\mathcal{L}}_{\mathrm{int}}=13{\mathrm{pb}}^{-1}$ . The results provide precise cross sections, transverse momentum ( $p_{\mathrm{T}}$ ) and rapidity ( $y$ ) spectra, as well as cross section ratios for $p_{\mathrm{T}}<10\mathrm{GeV}/\mathrm{c}$ and $\left|y\right|<1$ . The dependence of the $\mathrm{\Upsilon }$ yield on charged particle multiplicity has also been measured, offering new insights into the mechanisms of quarkonium production. The data are compared to various theoretical models: the color evaporation model (CEM) accurately describes the $\mathrm{\Upsilon }\left(1S\right)$ production, while the color glass $\mathrm{condensate}+\text{nonrelativistic}$ quantum chromodynamics ( $\mathrm{CGC}+\mathrm{NRQCD}$ ) model overestimates the data, particularly at low $p_{\mathrm{T}}$ . Conversely, the color singlet model (CSM) underestimates the rapidity dependence. These discrepancies highlight the need for further development in understanding the production dynamics of heavy quarkonia in high-energy hadronic collisions. The trend in the multiplicity dependence is consistent with CGC/saturation and string percolation models or $\mathrm{\Upsilon }$ production happening in multiple parton interactions modeled by 8. 

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4. Search for $h_b\left(2P\right)\to \gamma {\chi }_{bJ}\left(1P\right)$ at $\sqrt{s}=10.860\mathrm{GeV}$

   https://doi.org/10.1103/PhysRevD.111.L011102  

   Boschetti, A; Mussa, R; Tamponi, U; Adachi, I; Aihara, H; Asner, D M; Aushev, T; Ayad, R; Banerjee, Sw; Belous, K; et al (January 2025, Physical Review D)

   In the bottomonium sector, the hindered magnetic dipole transitions between P-wave states $h_b\left(2P\right)\to {\chi }_{bJ}\left(1P\right)\gamma$ , $J=0$ , 1, 2, are expected to be severely suppressed according to the relativized quark model, due to the spin flip of the $b$ quark. Nevertheless, a recent model following the coupled-channel approach predicts the corresponding branching fractions to be enhanced by orders of magnitude. In this Letter, we report the first search for such transitions. We find no significant signals and set upper limits at 90% confidence level on the corresponding branching fractions: $\mathcal{B}\left[h_b\right(2P)\to \gamma {\chi }_{b0}(1P\left)\right]<2.7\times {10}^{-1}$ , $\mathcal{B}\left[h_b\right(2P)\to \gamma {\chi }_{b1}(1P\left)\right]<5.4\times {10}^{-3}$ and $\mathcal{B}\left[h_b\right(2P)\to \gamma {\chi }_{b2}(1P\left)\right]<1.3\times {10}^{-2}$ . These values help to constrain the parameters of the coupled-channel models. The results are obtained using a $121.4{\mathrm{fb}}^{-1}$ data sample taken around $\sqrt{s}=10.860\mathrm{GeV}$ with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider. Published by the American Physical Society2025 

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5. Leptogenesis during an era of early SU(2) confinement

   https://doi.org/10.1103/nmpt-fwz6  

   Bhalla-Ladd, India; Ginnett, Izzy; Tait, Tim_M P (October 2025, Physical Review D)

   We explore leptogenesis during a cosmological epoch during which the electroweak $\mathrm{SU}(2{)}_L$ force is confined. During weak confinement, there is only one conserved nonanomalous global charge, $r$ , which is a linear combination of lepton-number, baryon-number, and hypercharge. The inclusion of heavy Majorana neutrinos leads to an $r$ -charge and $CP$ -violating interaction with a composite scalar, $\mathrm{\Phi }$ , and composite fermions, $\mathrm{\Psi }$ , allowing for the generation of an $r$ -charge asymmetry, which translates into a baryon asymmetry post $\mathrm{SU}(2{)}_L$ deconfinement. Determining the resulting baryon asymmetry as a function of the model parameters, we find that the predicted baryon-asymmetry can match observations for a wide swath of parameter space: a weak confinement scale ${\mathrm{\Lambda }}_W\sim {10}^{11}–{10}^{14}\mathrm{GeV}$ , the sum of the Standard Model Yukawa couplings $\sum Y_{i\alpha }{Y}_{i\alpha }^{*}\sim {10}^{-2}-{10}^0$ , $m_{\mathrm{\Phi }}/m_{\mathrm{\Psi }}\sim 0-0.5$ , and a $\mathrm{\Phi }-\mathrm{\Psi }-\mathrm{\Psi }$ coupling $\left|g\right|\sim 1$ with complex phase ${\theta }_g\sim \pi /4$ . While leptogenesis under the assumption of a standard cosmology relies on the complex phase of the neutrino Yukawa couplings, the asymmetry generated in this novel background cosmology primarily depends on a strong phase from $\mathrm{SU}(2{)}_L$ confinement, ${\theta }_g$ , and favors negligible $CP$ -violation in the right-handed neutrino decays. 

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