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1. Ising field theory in a magnetic field: φ3 coupling at T > Tc

   https://doi.org/10.1007/JHEP08(2023)161  

   Xu, Hao-Lan; Zamolodchikov, Alexander (August 2023, Journal of High Energy Physics)

   A<sc>bstract</sc> We study the “three particle coupling”$$ {\Gamma}_{11}^1\left(\xi \right) $$ ${\Gamma }_{11}^1\left(\xi \right)$, in 2dIsing Field Theory in a magnetic field, as the function of the scaling parameterξ:=h/(−m)^15/8, wherem∼T_c−Tandh∼Hare scaled deviation from the critical temperature and scaled external field, respectively. The “φ³coupling”$$ {\Gamma}_{11}^1 $$ ${\Gamma }_{11}^1$is defined in terms of the residue of the 2 → 2 elastic scattering amplitude at its pole associated with the lightest particle itself. We limit attention to the High-Temperature domain, so thatmis negative. We suggest “standard analyticity”:$$ {\left({\Gamma}_{11}^1\right)}^2 $$ ${\left({\Gamma }_{11}^1\right)}^2$, as the function ofu:=ξ², is analytic in the whole complexu-plane except for the branch cut from – ∞ to –u₀≈ – 0.03585, the latter branching point –u₀being associated with the Yang-Lee edge singularity. Under this assumption, the values of$$ {\Gamma}_{11}^1 $$ ${\Gamma }_{11}^1$at any complexuare expressed through the discontinuity across the branch cut. We suggest approximation for this discontinuity which accounts for singular expansion of$$ {\Gamma}_{11}^1 $$ ${\Gamma }_{11}^1$near the Yang-Lee branching point, as well as its known asymptotic atu →+∞. The resulting dispersion relation agrees well with known exact data, and with numerics obtained via Truncated Free Fermion Space Approach. This work is part of extended project of studying the S-matrix of the Ising Field Theory in a magnetic field. 

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2. Ward identities for superamplitudes

   https://doi.org/10.1007/JHEP06(2024)035  

   Kallosh, Renata (June 2024, Journal of High Energy Physics)

   A<sc>bstract</sc> We introduce Ward identities for superamplitudes inD-dimensional$$ \mathcal{N} $$ $N$-extended supergravities. These identities help to clarify the relation between linearized superinvariants and superamplitudes. The solutions of these Ward identities for ann-partice superamplitude take a simple universal form for half BPS and non-BPS amplitudes. These solutions involve arbitrary functions of spinor helicity and Grassmann variables for each of thensuperparticles. The dimension of these functions at a given loop order is exactly the same as the dimension of the relevant superspace Lagrangians depending on half-BPS or non-BPS superfields, given by (D− 2)L+ 2 −$$ \mathcal{N} $$ $N$or (D− 2)L+ 2 −$$ 2\mathcal{N} $$ $2N$, respectively. This explains why soft limits predictions from superamplitudes and from superspace linearized superinvariants agree. 

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3. Charged-particle production as a function of the relative transverse activity classifier in pp, p–Pb, and Pb–Pb collisions at the LHC

   https://doi.org/10.1007/JHEP01(2024)056  

   Acharya, S; Adamová, D; Aglieri_Rinella, G; Agnello, M; Agrawal, N; Ahammed, Z; Ahmad, S; Ahn, S U; Ahuja, I; Akindinov, A; et al (January 2024, Journal of High Energy Physics)

   A<sc>bstract</sc> Measurements of charged-particle production in pp, p–Pb, and Pb–Pb collisions in the toward, away, and transverse regions with the ALICE detector are discussed. These regions are defined event-by-event relative to the azimuthal direction of the charged trigger particle, which is the reconstructed particle with the largest transverse momentum$$ \left({p}_{\textrm{T}}^{\textrm{trig}}\right) $$ $\left(p_T^{\text{trig}}\right)$in the range 8<$$ {p}_{\textrm{T}}^{\textrm{trig}} $$ $p_T^{\text{trig}}$<15 GeV/c. The toward and away regions contain the primary and recoil jets, respectively; both regions are accompanied by the underlying event (UE). In contrast, the transverse region perpendicular to the direction of the trigger particle is dominated by the so-called UE dynamics, and includes also contributions from initial- and final-state radiation. The relative transverse activity classifier,$$ {R}_{\textrm{T}}={N}_{\textrm{ch}}^{\textrm{T}}/\left\langle {N}_{\textrm{ch}}^{\textrm{T}}\right\rangle $$ $R_T=N_{\mathrm{ch}}^T/\left(N_{\mathrm{ch}}^T\right)$, is used to group events according to their UE activity, where$$ {N}_{\textrm{ch}}^{\textrm{T}} $$ $N_{\mathrm{ch}}^T$is the charged-particle multiplicity per event in the transverse region and$$ \left\langle {N}_{\textrm{ch}}^{\textrm{T}}\right\rangle $$ $\left(N_{\mathrm{ch}}^T\right)$is the mean value over the whole analysed sample. The energy dependence of theR_Tdistributions in pp collisions at$$ \sqrt{s} $$ $\sqrt{s}$= 2.76, 5.02, 7, and 13 TeV is reported, exploring the Koba-Nielsen-Olesen (KNO) scaling properties of the multiplicity distributions. The first measurements of charged-particlep_Tspectra as a function ofR_Tin the three azimuthal regions in pp, p–Pb, and Pb–Pb collisions at$$ \sqrt{s_{\textrm{NN}}} $$ $\sqrt{s_{\mathrm{NN}}}$= 5.02 TeV are also reported. Data are compared with predictions obtained from the event generators PYTHIA 8 and EPOS LHC. This set of measurements is expected to contribute to the understanding of the origin of collective-like effects in small collision systems (pp and p–Pb). 

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4. Notes on gauging noninvertible symmetries. Part I. Multiplicity-free cases

   https://doi.org/10.1007/JHEP02(2024)154  

   Perez-Lona, A; Robbins, D; Sharpe, E; Vandermeulen, T; Yu, X (February 2024, Journal of High Energy Physics)

   A<sc>bstract</sc> In this paper we discuss gauging noninvertible zero-form symmetries in two dimensions. We specialize to certain gaugeable cases, specifically, fusion categories of the form$$ \textrm{Rep}\left(\mathcal{H}\right) $$ $\mathrm{Rep}\left(H\right)$for$$ \mathcal{H} $$ $H$a suitable Hopf algebra (which includes the special case Rep(G) forGa finite group). We also specialize to the case that the fusion category is multiplicity-free. We discuss how to construct a modular-invariant partition function from a choice of Frobenius algebra structure on$$ {\mathcal{H}}^{\ast } $$ $H^{\ast }$. We discuss how ordinaryGorbifolds for finite groupsGare a special case of the construction, corresponding to the fusion category Vec(G) = Rep(ℂ[G]^*). For the cases Rep(S₃), Rep(D₄), and Rep(Q₈), we construct the crossing kernels for general intertwiner maps. We explicitly compute partition functions in the examples of Rep(S₃), Rep(D₄), Rep(Q₈), and$$ \textrm{Rep}\left({\mathcal{H}}_8\right) $$ $\mathrm{Rep}\left(H_8\right)$, and discuss applications inc= 1 CFTs. We also discuss decomposition in the special case that the entire noninvertible symmetry group acts trivially. 

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5. $$ \mathcal{N} $$ = 2 JT supergravity and matrix models

   https://doi.org/10.1007/JHEP12(2023)003  

   Turiaci, Gustavo J.; Witten, Edward (December 2023, Journal of High Energy Physics)

   A<sc>bstract</sc> Generalizing previous results for$$ \mathcal{N} $$ $N$= 0 and$$ \mathcal{N} $$ $N$= 1, we analyze$$ \mathcal{N} $$ $N$= 2 JT supergravity on asymptotically AdS₂spaces with arbitrary topology and show that this theory of gravity is dual, in a holographic sense, to a certain random matrix ensemble in which supermultiplets of differentR-charge are statistically independent and each is described by its own$$ \mathcal{N} $$ $N$= 2 random matrix ensemble. We also analyze the case with a time-reversal symmetry, either commuting or anticommuting with theR-charge. In order to compare supergravity to random matrix theory, we develop an$$ \mathcal{N} $$ $N$= 2 analog of the recursion relations for Weil-Petersson volumes originally discovered by Mirzakhani in the bosonic case. 

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