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1. Determination of the Relative Sign of the Higgs Boson Couplings to $W$ and $Z$ Bosons Using $WH$ Production via Vector-Boson Fusion with the ATLAS Detector

   https://doi.org/10.1103/PhysRevLett.133.141801  

   Aad, G; Abbott, B; Abeling, K; Abicht, N J; Abidi, S H; Aboulhorma, A; Abramowicz, H; Abreu, H; Abulaiti, Y; Acharya, B S; et al (October 2024, Physical Review Letters)

   The associated production of Higgs and $W$bosons via vector-boson fusion is highly sensitive to the relative sign of the Higgs boson couplings to $W$and $Z$bosons. In this Letter, two searches for this process are presented, using $140{\mathrm{fb}}^{-1}$of proton-proton collision data at $\sqrt{s}=13\mathrm{TeV}$recorded by the ATLAS detector at the LHC. The first search targets scenarios with opposite-sign couplings of the $W$and $Z$bosons to the Higgs boson, while the second targets standard model-like scenarios with same-sign couplings. Both analyses consider Higgs boson decays into a pair of $b$quarks and $W$boson decays with an electron or muon. The data exclude the opposite-sign coupling hypothesis with a significance beyond $5\sigma$, and the observed (expected) upper limit set on the cross section for vector-boson fusion $WH$production is 9.0 (8.7) times the standard model value at 95% confidence level. © 2024 CERN, for the ATLAS Collaboration2024CERN 

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2. Transverse energy-energy correlator for vector boson-tagged hadron production in $pp$ and $pA$ collisions

   https://doi.org/10.1103/1djw-8zrh  

   Kang, Zhong-Bo; Lee, Sookhyun; Penttala, Jani; Zhao, Fanyi; Zhou, Yiyu (July 2025, Physical Review D)

   We investigate the transverse energy-energy correlator (TEEC) event-shape observable for back-to-back $\gamma +h$and $Z+h$production in both $pp$and $pA$collisions. Our study incorporates nuclear modifications into the transverse-momentum dependent (TMD) factorization framework, with resummation up to next-to-leading logarithmic accuracy, for TEEC as a function of the variable $\tau =(1+\cos \varphi )/2$, where $\varphi$is the azimuthal angle between the vector boson and the final hadron. We analyze the nuclear modification factor $R_{pA}$in $p\mathrm{Au}$collisions at Relativistic Heavy Ion Collider and $p\mathrm{Pb}$collisions at the Large Hadron Collider. Our results demonstrate that the TEEC observable is a sensitive probe for nuclear modifications in TMD physics. Specifically, the changes in the $\tau$-distribution shape provide insights into transverse momentum broadening effects in large nuclei, while measurements at different rapidities allow us to explore nuclear modifications in the collinear component of the TMD parton distribution functions in nuclei. 

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3. Strong $CP$ and flavor in multi-Higgs theories

   https://doi.org/10.1103/rxml-5gd2  

   Hall, Lawrence; Manzari, Claudio Andrea; Noether, Bea (June 2025, Physical Review D)

   We introduce a class of multi-Higgs doublet extensions of the Standard Model that solve the strong $CP$problem with profound consequences for the flavor sector. The Yukawa matrices are constrained to have many zero entries by a “Higgs-flavor” symmetry, $G_{\mathrm{HF}}$, that acts on Higgs and quark fields. The violation of both $CP$and $G_{\mathrm{HF}}$occurs in the Higgs mass matrix so that, for certain choices of $G_{\mathrm{HF}}$charges, the strong $CP$parameter $\overline{\theta }$is zero at tree level. Radiative corrections to $\overline{\theta }$are computed in this class of theories. They vanish in realistic two-Higgs doublet models with $G_{\mathrm{HF}}={\mathbb{Z}}_3$. We also construct realistic three-Higgs models with $G_{\mathrm{HF}}=\mathrm{U}\left(1\right)$, where the one-loop results for $\overline{\theta }$are model-dependent. Requiring $\overline{\theta }<{10}^{-10}$has important implications for the flavor problem by constraining the Yukawa coupling and Higgs mass matrices. Contributions to $\overline{\theta }$from higher-dimension operators are computed at one loop and can also be sufficiently small, although the hierarchy problem of this class of theories is worse than in the Standard Model. 

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4. Observation of Medium-Induced Yield Enhancement and Acoplanarity Broadening of Low- $p_{\mathrm{T}}$ Jets from Measurements in $pp$ and Central Pb-Pb Collisions at $\sqrt{s_{\mathrm{NN}}}=5.02\mathrm{TeV}$

   https://doi.org/10.1103/PhysRevLett.133.022301  

   Acharya, S; Adamová, D; Aglieri_Rinella, G; Agnello, M; Agrawal, N; Ahammed, Z; Ahmad, S; Ahn, S U; Ahuja, I; Akindinov, A; et al (July 2024, Physical Review Letters)

   The ALICE Collaboration reports the measurement of semi-inclusive distributions of charged-particle jets recoiling from a high transverse momentum (high $p_{\mathrm{T}}$) hadron trigger in proton-proton and central Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.02\mathrm{TeV}$. A data-driven statistical method is used to mitigate the large uncorrelated background in central Pb-Pb collisions. Recoil jet distributions are reported for jet resolution parameter $R=0.2$, 0.4, and 0.5 in the range $7<p_{\mathrm{T},\text{jet}}<140\mathrm{GeV}/c$and trigger-recoil jet azimuthal separation $\pi /2<\mathrm{\Delta }\phi <\pi$. The measurements exhibit a marked medium-induced jet yield enhancement at low $p_{\mathrm{T}}$and at large azimuthal deviation from $\mathrm{\Delta }\phi \sim \pi$. The enhancement is characterized by its dependence on $\mathrm{\Delta }\phi$, which has a slope that differs from zero by $4.7\sigma$. Comparisons to model calculations incorporating different formulations of jet quenching are reported. These comparisons indicate that the observed yield enhancement arises from the response of the QGP medium to jet propagation. © 2024 CERN, for the ALICE Collaboration2024CERN 

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5. Probing Gluon Fluctuations in Nuclei with the First Energy-Dependent Measurement of Incoherent $J/\psi$ Photoproduction in Ultraperipheral PbPb Collisions

   https://doi.org/10.1103/w9kp-f8xr  

   Chekhovsky, V; Hayrapetyan, A; Makarenko, V; Tumasyan, A; Adam, W; Andrejkovic, J W; Benato, L; Bergauer, T; Chatterjee, S; Damanakis, K; et al (September 2025, Physical Review Letters)

   Incoherent $J/\psi$photoproduction in heavy ion ultraperipheral collisions (UPCs) provides a sensitive probe of localized, fluctuating gluonic structures within heavy nuclei. This Letter reports the first measurement of the photon-nucleon center-of-mass energy ( $W_{\gamma \mathrm{N}}$) dependence of this process in PbPb UPCs at a nucleon-nucleon center-of-mass energy of 5.02 TeV, using $1.52{\mathrm{nb}}^{-1}$of data recorded by the CMS experiment. The measurement covers a wide $W_{\gamma \mathrm{N}}$range of $\approx 40–400\mathrm{GeV}$, probing gluons carrying a fraction $x$of nucleon momentum down to an unexplored regime of $6.5\times {10}^{-5}$. Compared to baseline predictions neglecting nuclear effects, the measured cross sections exhibit significantly greater suppression at lower $x$. Additionally, the ratio of incoherent to coherent photoproduction is found to be constant across the probed $W_{\gamma \mathrm{N}}$and $x$range, disfavoring the establishment of the black disk limit. This Letter provides critical insights into the $x$-dependent evolution of fluctuating gluonic structures within nuclei and calls for further advancements in theoretical models incorporating nuclear shadowing and gluon saturation. 

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