Fri·Oct 27, 2023Friday·October 27, 2023

1. 01*

   Towards high-energy Higgs+jet distributions at NLL matched to NLO

   Francesco Giovanni Celiberto🇪🇸 · Luigi Delle Rose🇮🇹 · Michael Fucilla🇫🇷 · Gabriele Gatto🇮🇹 · Alessandro Papa🇮🇹

   We report progress on the study of the inclusive semi-hard hadroproduction of a Higgs+jet system at LHC and FCC collision energies. We describe a prototype matching procedure aimed at combining NLO fixed-order computations via POWHEG, with the NLL resummation of energy logarithms from JETHAD. We present preliminary analyses on assessing the weight of systematic uncertainties, such as the ones coming from finite top- and bottom-quark masses.

   hep-phhep-exPoS(2024)·24 citations
2. 02*

   Novel moduli space in modular flavor models : a case study for modular $T^{\prime }$ seesaw model with hidden $SU(2)$ gauge symmetry

   Keiya Ishiguro🇯🇵 · Takaaki Nomura🇨🇳 · Hiroshi Okada🇯🇵 · Yuta Orikasa🇨🇿 · Hajime Otsuka🇯🇵

   We study flavor phenomenologies in a basis of a double covering of modular $A_4$ group with a hidden $SU(2)$ symmetry, in which we work on regions at nearby two fixed points and three special points. These special points of $SL(2,\mathbb{Z})$ moduli space are statistically favored in flux compactifications of Type IIB string theory. Neutrino masses are approximately obtained by using the seesaw mechanism due to our two additional symmetries. We perform chi square numerical analysis for each of the fixed/special points in the normal and inverted hierarchies and demonstrate predictions for each case. Then, we briefly discuss the possible signature of hidden gauge bosons at collider experiments from the hidden $SU(2)$ symmetry.

   hep-ph0 citations
3. 03*

   Effective field theory of particle mixing

   Shuyang Cao🇺🇸 · Daniel Boyanovsky🇺🇸

   We introduce an effective field theory to study \emph{indirect} mixing of two fields induced by their couplings to a common decay channel in a medium. The extension of the method of Lee, Oehme and Yang, the cornerstone of analysis of CP violation in flavored mesons, to include mixing of particles with different masses provides a guide to and benchmark for the effective field theory. The analysis reveals subtle caveats in the description of mixing in terms of the widely used non-Hermitian effective Hamiltonian, more acute in the non-degenerate case. The effective field theory describes the dynamics of field mixing where the common intermediate states populate a bath in thermal equilibrium, as an \emph{open quantum system}. We obtain the effective action up to second order in the couplings, where indirect mixing is a consequence of off-diagonal self-energy components. We find that if only one of the mixing fields features an initial expectation value, indirect mixing induces an expectation value of the other field. The equal time two point correlation functions exhibit asymptotic approach to a stationary thermal state, and the emergence of long-lived \emph{bath induced} coherence which display quantum beats as a consequence of interference of quasinormal modes in the medium. The amplitudes of the quantum beats are resonantly enhanced in the nearly degenerate case with potential observational consequences.

   hep-phcond-mat.otherhep-thquant-phPRD(2024)·8 citations
4. 04*

   The production of charmonium pentaquark from b-baryon and B-meson decay: SU(3) analysis

   Wei-Hao Han🇨🇳 · Ye Xing🇨🇳 · Ji Xu🇨🇳

   In this paper, we study the production of charmonium pentaquark $c\bar{c}qqq$ from bottom baryon and B-meson decays under the flavor SU(3) symmetry. Decay amplitudes for various processes are parametrized in terms of the SU(3) irreducible nonperturbative amplitudes. A number of relations between decay widths have been deduced. Moreover, the strong decays of pentaquark is also taken into account. These results can be tested in future measurements at LHCb, Belle II and CEPC. Once a few decay branching fractions have been measured, our work could provide hints for exploring new decay channels or new pentaquark states.

   hep-phCPC(2024)·7 citations
5. 05*

   Long-lived heavy neutral leptons at lepton colliders as a probe of left-right symmetric models

   Kevin A. Urquía-Calderón🇩🇰

   Left-right symmetric models (LRSM) were proposed to reconcile the apparent parity violation in weak interactions with our intrinsic notion of fundamental parity symmetry. It was quickly realized that LRSM offers a viable framework for explaining neutrino masses by incorporating right-handed neutrinos, $N$, into its spectrum. In this study, we investigate for the first time the potential of future lepton colliders (including the FCC-ee, CEPC, ILC, CLIC, and a muon collider) to detect signals stemming from $N$'s, focusing primarily on displaced vertex signals, and on prompt signals to a lesser degree. Our results demonstrate that these signals can effectively probe the characteristic scales of LRSM, providing evidence that would be unobtainable through any other experimental means.

   hep-phPRD(2024)·23 citations
6. 06*

   Resummation schemes for high-electric-charge objects leading to improved experimental mass limits

   Jean Alexandre🇬🇧 · Nick E. Mavromatos🇬🇷 · Vasiliki A. Mitsou🇪🇸 · Emanuela Musumeci🇪🇸

   High-Electric-Charge compact Objects (HECOs) appear in several theoretical particle physics models beyond the Standard Model, and are actively searched for in current colliders, such as the Large Hadron Collider at CERN. In such searches, mass bounds of these objects have been placed, using Drell-Yan and photon-fusion processes at tree level so far. However, such mass-bound estimates are not reliable, given that, as a result of the large values of the electric charge of the HECO, perturbative Quantum Electrodynamics calculations break down. In this work, we perform a Dyson-Schwinger resummation scheme (as opposed to lattice strong-coupling approach), which makes the computation of the pertinent HECO-production cross sections reliable, thus allowing us to extract improved mass bounds for such objects from ATLAS and MoEDAL searches.

   hep-phhep-exhep-thPRD(2024)·14 citations
7. 07*

   Soft supersymmetry breaking as the sole origin of neutrino masses and lepton number violation

   Anjan S. Joshipura🇮🇳 · Ketan M. Patel🇮🇳

   We discuss a scenario in which the supergravity induced soft terms, conventionally used for breaking supersymmetry, also lead to non-zero Majorana neutrino masses. The soft terms lead to the spontaneous violation of the lepton number at the gravitino mass scale $m_{3/2}$ which in turn leads to (i) the Majorana masses of $\mathcal{O}(m_{3/2})$ for the right-handed neutrinos and (ii) the $R$-parity breaking at the same scale. The former contributes to light neutrino masses through the type I seesaw mechanism, while the latter adds to it through neutrino-neutralino mixing. Both contributions can scale inversely with respect to $m_{3/2}$ given that gaugino and Higgsino masses are also of order $m_{3/2}$. Together, these two contributions adequately explain observed neutrino masses and mixing. One realization of the scenario also naturally leads to a $\mu$ parameter of $\mathcal{O}(m_{3/2})$. Despite the lepton number symmetry breaking close to the weak scale, the Majoron in the model exhibits very weak coupling to leptons, satisfying existing constraints on Majoron-lepton interactions. The right-handed neutrinos in the model have a large coupling to Higgsinos. This coupling and the relatively large heavy-light neutrino mixing induced through the seesaw mechanism may lead to the observable signals at colliders in terms of displaced vertices.

   hep-phJHEP(2024)·0 citations
8. 08*

   Decay constants of $c\bar{b}$ mesons involving the ten heavy flavor-changing currents at N${}^3$LO QCD

   Wei Tao🇨🇳 · Zhen-Jun Xiao🇨🇳

   Within the nonrelativistic QCD (NRQCD) framework, we complete the three-loop calculations of the NRQCD renormalization constants and the matching coefficients, for the heavy flavor-changing temporal vector, spatial-spatial tensor, spatial-temporal axial-tensor currents, which are coupled to the $P$-wave $c\bar{b}$ mesons. We further study the ten decay constants for the $c\bar{b}$ mesons ($B_c,B_c^{\ast },B_{c0}^{\ast },B_{c1}$) coupled with the ten heavy flavor-changing currents involving (pseudo-)scalar, (axial-)vector and (axial-)tensor up to the next-to-next-to-next-to-leading order (N${}^3$LO) of ${\alpha }_s$. We obtain the six ratios of decay constants by approximating them to the corresponding ratios of matching coefficients. We find the N${}^3$LO QCD corrections to the six ratios of decay constants have good convergence and weak scale-dependence. We finally predict the hierarchical relationship among the ten decay constants for the $c\bar{b}$ mesons coupled with the ten currents.

   hep-phJHEP(2024)·5 citations
9. 09*

   Energy levels of mesonic helium in quantum electrodynamics

   V.I. Korobov🇷🇺 · A.V. Eskin🇷🇺 · A.P. Martynenko🇷🇺 · F.A. Martynenko🇷🇺

   On the basis of variational method we study energy levels of pionic helium $(\pi -e-He)$ and kaonic helium $(K-e-He)$ with an electron in ground state and a meson in excited state with principal and orbital quantum numbers $n\sim l+1\sim 20$. Variational wave functions are taken in the Gaussian form. Matrix elements of the basic Hamiltonian and corrections to vacuum polarization and relativism are calculated analytically in a closed form. We calculate some bound state energies and transition frequencies which can be studied in the experiment.

   hep-phphysics.atom-phPRA(2024)·7 citations
10. 10*

    Domain-wall Skyrmion phase in a rapidly rotating QCD matter

    Minoru Eto🇯🇵 · Kentaro Nishimura🇯🇵 · Muneto Nitta🇯🇵

    Based on the chiral perturbation theory at the leading order, we show the presence of a new phase in rapidly rotating QCD matter with two flavors, that is a domain-wall Skyrmion phase. Based on the chiral Lagrangian with a Wess-Zumino-Witten (WZW) term responsible for the chiral anomaly and chiral vortical effect, it was shown that the ground state is a chiral soliton lattice(CSL) consisting of a stack of $\eta$-solitons in a high density region under rapid rotation. In a large parameter region, a single $\eta$-soliton decays into a pair of non-Abelian solitons, each of which carries $\mathrm{SU}(2{)}_{\mathrm{V}}/\mathrm{U}(1)\simeq \mathbb{C}{P}^1\simeq S^2$ moduli as a consequence of the spontaneously broken vector symmetry $\mathrm{SU}(2{)}_{\mathrm{V}}$. In such a non-Abelian CSL, we construct the effective world-volume theory of a single non-Abelian soliton to obtain a $d=2+1$ dimensional $\mathbb{C}{P}^1$ model with a topological term originated from the WZW term. We show that when the chemical potential is larger than a critical value, a topological lump supported by the second homotopy group ${\pi }_2(S^2)\simeq \mathbb{Z}$ has negative energy and is spontaneously created, implying the domain-wall Skyrmion phase. This lump corresponds in the bulk to a Skyrmion supported by the third homotopy group ${\pi }_3[\mathrm{SU}(2)]\simeq \mathbb{Z}$ carrying a baryon number. This composite state is called a domain-wall Skyrmion, and is stable even in the absence of the Skyrme term. An analytic formula for the effective nucleon mass in this medium is obtained as $4\sqrt{2}\pi f_{\pi }{f}_{\eta }/m_{\pi }\sim 1.21$ GeV with the decay constants $f_{\pi }$ and $f_{\eta }$ of the pions and $\eta$ meson, respectively, and the pion mass $m_{\pi }$, which is surprisingly close to the nucleon mass in the QCD vacuum.

    hep-phhep-thnucl-thJHEP(2024)·32 citations
11. 11*

    A fresh look at the nested soft-collinear subtraction scheme: NNLO QCD corrections to $N$-gluon final states in $q\bar{q}$ annihilation

    Federica Devoto🇬🇧 · Kirill Melnikov🇩🇪 · Raoul Röntsch🇮🇹 · Chiara Signorile-Signorile🇩🇪 · Davide Maria Tagliabue🇮🇹

    We describe how the nested soft-collinear subtraction scheme [1] can be used to compute the next-to-next-to-leading order (NNLO) QCD corrections to the production of an arbitrary number of gluonic jets in hadron collisions. We show that the infrared subtraction terms can be combined into recurring structures that in many cases are simple iterations of those terms known from next-to-leading order. The way that these recurring structures are identified and computed is fairly general, and can be applied to any partonic process. As an example, we explicitly demonstrate the cancellation of all singularities in the fully-differential cross section for the $q\bar{q}\to X+Ng$ process at NNLO in QCD. The finite remainder of the NNLO QCD contribution, which arises upon cancellation of all $ϵ$-poles, is expressed via relatively simple formulas, which can be implemented in a numerical code in a straightforward way. Our approach can be extended to describe arbitrary processes at NNLO in QCD; the largest remaining challenge at this point is the combinatorics of quark and gluon collinear limits.

    hep-phJHEP(2024)·45 citations
12. 12*

    Experimental prospects for indirect BSM searches in $e^{-}{e}^{+}\to q\bar{q}$ ($q=c,b$) processes at Higgs Factories

    J.P. Marquez🇪🇸

    This contribution explores the ability to probe BSM physics by using the experimental prospects for measuring the forward-backward asymmetry ($A_{FB}$) in $e^{+}{e}^{-}\to b\bar{b}$ and $e^{+}{e}^{-}\to c\bar{c}$ processes at the baseline energy points of ILC: 250 and 500 GeV. The studies are based on the full simulation samples and reconstruction chains from the ILD concept group. The BSM models studied are two different types of gauge-Higgs unification (GHU) models that predict BSM Z${}^{\prime }$ resonances at the TeV scale.

    hep-phhep-exPoS(2024)·4 citations
13. 13*

    Heavy quark fragmentation function in 't Hooft Model

    Yu Jia🇨🇳 · Zhewen Mo🇨🇳 · Xiaonu Xiong🇨🇳

    We carry out a comprehensive study of the quark-to-meson fragmentation function in the 't Hooft model, i.e., the two-dimensional Quantum Chromodynamics (QCD) in $N_c\to \infty$ limit, following the operator definition pioneered by Collins and Soper. We apply the Hamiltonian approach as well as the diagrammatic approach to construct the functional form of the quark-to-meson fragmentation function in terms of the meson's light-cone wave function. For the sake of comparison, we also investigate the heavy quark fragmentation into quarkonium in two-dimensional QCD within the framework of the nonrelativistic QCD (NRQCD) factorization, at the lowest order in quark velocity. In the heavy quark limit, the quark fragmentation function obtained from the {\it ab initio} method agrees well, both analytically and numerically, with that obtained from the NRQCD approach. This agreement might be regarded as a nontrivial justification for the validity of both field-theoretical approaches to compute the heavy quark fragmentation function.

    hep-phEPJC(2023)·3 citations
14. 14*

    Neutrino Oscillations and Mass Models

    Aditya Dev🇮🇳

    These notes provide a review of various neutrino mass model and their implications for particle physics and the Standard Model. We discuss how mass terms are incorporated into the Standard Model, including the Dirac mass term and the Majorana mechanism. We explore experimental evidence supporting the existence of non-zero neutrino mass and develop the formalism of neutrino oscillations. Additionally, we provide a brief overview of some famous radiative neutrino mass models. This notes draws heavily from the references given below and can serve as a valuable resource for students and new researchers interested in the field of neutrino physics.

    hep-ph3 citations
15. 15*

    Improved Standard-Model prediction for $K_L\to {\ell }^{+}{\ell }^{-}$

    Martin Hoferichter🇨🇭 · Bai-Long Hoid🇨🇭 · Jacobo Ruiz de Elvira🇪🇸

    We present a comprehensive calculation of the $K_L\to {\gamma }^{\ast }{\gamma }^{\ast }$ form factor in dispersion theory, using input from the leptonic decays $K_L\to {\ell }^{+}{\ell }^{-}\gamma$, $K_L\to {\ell }_1^{+}{\ell }_1^{-}{\ell }_2^{+}{\ell }_2^{-}$, the hadronic mode $K_L\to {\pi }^{+}{\pi }^{-}\gamma$, the normalization $K_L\to \gamma \gamma$, and the matching to asymptotic constraints. As key result we obtain an improved determination of the long-distance contribution to $K_L\to {\ell }^{+}{\ell }^{-}$, leading to the Standard-Model predictions $\text{Br}[K_L\to {\mu }^{+}{\mu }^{-}]=7.44_{-0.34}^{+0.41}\times 10^{-9}$, $\text{Br}[K_L\to e^{+}{e}^{-}]=8.46(37)\times 10^{-12}$, and more stringent limits on physics beyond the Standard Model. We provide a detailed breakdown of the current uncertainty, and delineate how future experiments and the interplay with lattice QCD could help further improve the precision.

    hep-phhep-exhep-latnucl-thJHEP(2024)·21 citations
16. 16*

    Quantum Entanglement and Bell Inequality Violation in Semi-Leptonic Top Decays

    Tao Han🇺🇸 · Matthew Low🇺🇸 · Tong Arthur Wu🇺🇸

    Quantum entanglement is a fundamental property of quantum mechanics. Recently, studies have explored entanglement in the $t\bar{t}$ system at the Large Hadron Collider (LHC) when both the top quark and anti-top quark decay leptonically. Entanglement is detected via correlations between the polarizations of the top and anti-top and these polarizations are measured through the angles of the decay products of the top and anti-top. In this work, we propose searching for evidence of quantum entanglement in the semi-leptonic decay channel where the final state includes one lepton, one neutrino, two $b$-flavor tagged jets, and two light jets from the $W$ decay. We find that this channel is both easier to reconstruct and has a larger effective quantity of data than the fully leptonic channel. As a result, the semi-leptonic channel is $60\%$ more sensitive to quantum entanglement and a factor of 3 more sensitive to Bell inequality violation, compared to the leptonic channel. In $139{\mathrm{fb}}^{-1}$ ($3{\mathrm{ab}}^{-1}$) of data at the LHC (HL-LHC), it should be feasible to measure entanglement at a precision of $\lesssim 3\%(0.7\%)$. Detecting Bell inequality violation, on the other hand, is more challenging. With $300{\mathrm{fb}}^{-1}$ ($3{\mathrm{ab}}^{-1}$) of integrated luminosity at the LHC Run-3 (HL-LHC), we expect a sensitivity of $1.3\sigma$ ($4.1\sigma$). In our study, we utilize a realistic parametric fitting procedure to optimally recover the true angular distributions from detector effects. Compared to unfolding this procedure yields more stable results.

    hep-phJHEP(2024)·109 citations
17. 17*

    Observational Constraints on Dynamical Dark Energy Models

    Olga Avsajanishvili🇬🇪 · Gennady Y. Chitov🇷🇺 · Tina Kahniashvili🇺🇸 · Sayan Mandal🇺🇸 · Lado Samushia🇺🇸

    $\varphi$CDM models provide an alternative to the standard $\Lambda$CDM paradigm, while being physically better motivated. These models lead to a time-dependent speed of sound for dark energy that is difficult to replicate by $w$CDM parametrizations. We review the most up-to-date status of observational evidence for the $\varphi$CDM models in this paper. We start with an overview of the motivation behind these classes of models, the basic mathematical formalism, and the different classes of models. We then present a compilation of recent results of applying different observational probes to constraining $\varphi$CDM model parameters. Over the last twenty years, the precision of observational data has increased immensely, leading to ever tighter constraints. A combination of the recent measurements favors the spatially flat $\Lambda$CDM model, but a large class of $\varphi$CDM models is still not ruled out.

    ↳ astro-ph.COgr-qchep-phUniverse(2024)·31 citations
18. 18*

    Confinement from Distance in Metric Space and its Relation to Cosmological Constant

    Amineh Mohseni🇮🇷 · Mahdi Torabian🇮🇷

    We argue that, in a theory of quantum gravity, the gauge coupling and the confinement scale of a gauge theory are related to distance in the space of metric configurations, and in turn to the cosmological constant. To support the argument, we compute the gauge kinetic functions in variuos supersymmetric Heterotic and type II string compactifications and show that they depend on distance. According to the swampland program, the distance between two (anti) de Sitter vacua in the space of metric configurations is proportional to the logarithm of the ratio of cosmological constants and thus the confinement scale depends on the value of the cosmological constant. In this framework, for de Sitter space, we revisit the swampland Festina Lente bound and gauge theories in the dark dimension scenario. We show that if the Festina Lente bound is realized in a de Sitter vacuum and dependence on distance is strong enough, it will be realized in vacua with higher cosmological constants. In dark dimension scenario, as the value of cosmological constant is related to the decompactifying dimension, we find that the confinement scale is indeed related to radius of dark dimension. We show that in this scenario the Festina Lente bound holds for the standard model QCD, as well as all confining gauge groups with $N_c\lesssim 10^3$.

    ↳ hep-thgr-qchep-phJHEP(2024)·4 citations
19. 19*

    Event-by-event Comparison between Machine-Learning- and Transfer-Matrix-based Unfolding Methods

    Mathias Backes🇩🇪 · Anja Butter🇫🇷 · Monica Dunford🇩🇪 · Bogdan Malaescu🇫🇷

    The unfolding of detector effects is a key aspect of comparing experimental data with theoretical predictions. In recent years, different Machine-Learning methods have been developed to provide novel features, e.g. high dimensionality or a probabilistic single-event unfolding based on generative neural networks. Traditionally, many analyses unfold detector effects using transfer-matrix--based algorithms, which are well established in low-dimensional unfolding. They yield an unfolded distribution of the total spectrum, together with its covariance matrix. This paper proposes a method to obtain probabilistic single-event unfolded distributions, together with their uncertainties and correlations, for the transfer-matrix--based unfolding. The algorithm is first validated on a toy model and then applied to pseudo-data for the $pp\to Z\gamma \gamma$ process. In both examples the performance is compared to the Machine-Learning--based single-event unfolding using an iterative approach with conditional invertible neural networks (IcINN).

    ↳ physics.data-anhep-exhep-phEPJC(2024)·10 citations
20. 20*

    Dark matter signatures of black holes with Yukawa potential

    A. A. Araújo Filho🇪🇸 · Kimet Jusufi🇲🇰 · B. Cuadros-Melgar🇧🇷 · Genly Leon🇨🇱

    This study uses a nonsingular Yukawa--modified potential to obtain a static and spherically symmetric black hole solution with a cosmological constant. Such Yukawa--like corrections are encoded in two parameters, $\alpha$ and $\lambda$, that modify Newton's law of gravity in large distances, and a deformation parameter ${\ell }_0$, which plays an essential role in short distances. The most significant effect is encoded in $\alpha$, which modifies the total black hole mass with an extra mass proportional to $\alpha M$, mimicking the dark matter effects at large distances from the black hole. On the other hand, the effect due to $\lambda$ is small for astrophysical values. We scrutinize the \textit{quasinormal} frequencies and shadows associated with a spherically symmetric black hole and the thermodynamical behavior influenced by the Yukawa potential. In particular, the thermodynamics of this black hole displays a rich behavior, including possible phase transitions. We use the WKB method to probe the \textit{quasinormal} modes of massless scalar, electromagnetic, and gravitational field perturbations. In order to check the influence of the parameters on the shadow radius, we consider astrophysical data to determine their values, incorporating information on an optically thin radiating and infalling gas surrounding a black hole to model the black hole shadow image. In particular, we consider Sgr A* black hole as an example and we find that its shadow radius changes by order of $10^{-9}$, meaning that the shadow radius of a black hole with Yukawa potential practically gives rise to the same result encountered in the Schwarzschild black hole. Also, in the eikonal regime, using astrophysical data for Yukawa parameters, we show that the value of the real part of the QNMs frequencies changes by $10^{-18}$.

    ↳ gr-qcastro-ph.HEhep-phhep-thPhys.Dark Univ.(2024)·29 citations
21. 21*

    Searches for axion-like particles via $\gamma \gamma$ fusion at future ${\mathrm{e}}^{+}{\mathrm{e}}^{-}$ colliders

    Patricia Rebello Teles🇧🇷 · David d'Enterria🇨🇭 · Victor P. Gonçalves🇧🇷 · Daniel E. Martins🇵🇱

    Opportunities for searches for axion-like particles (ALPs) coupling to photons in ${\mathrm{e}}^{+}{\mathrm{e}}^{-}$ collisions at the Future Circular Collider (FCC-ee) and International Linear Collider (ILC) are investigated. We perform a study of the photon-fusion production of ALPs decaying into two photons, ${\mathrm{e}}^{+}{\mathrm{e}}^{-}\stackrel{\gamma \gamma }{⟶}{\mathrm{e}}^{+}a(\gamma \gamma ){\mathrm{e}}^{-}$, over the light-by-light continuum background, for the planned FCC-ee and ILC center-of-mass energies and integrated luminosities. An analysis of the feasibility measurements is presented using parametrized simulations for two types of detectors. Upper limits at 95% confidence level (CL) on the cross section for ALP production, $\sigma (\gamma \gamma \to a\to \gamma \gamma )$, and on the ALP-photon coupling are obtained over the $m_a\approx 0.1$--1000 GeV ALP mass range, and compared to current and future collider searches. Production cross sections down to $\sigma (\gamma \gamma \to a\to \gamma \gamma )\approx 1$ fb (1 ab) will be probed at $m_a\approx 1$ (300) GeV, corresponding to constraints on the axion-photon coupling as low as $g_{\mathrm{a}\gamma \gamma }\approx 2\cdot 10^{-3}$ TeV${}^{-1}$.

    ↳ hep-exhep-phPRD(2024)·29 citations
22. 22*

    Baryon density dependence of viscosities of the quark-gluon plasma at hadronization

    Zhidong Yang🇨🇳 · Yifeng Sun🇨🇳 · Lie-Wen Chen🇨🇳

    The $\varphi$ meson and $\Omega$ baryon provide unique probes of the properties of the quark-gluon plasma (QGP) at hadronization in relativistic heavy-ion collisions. Using the quark recombination model with the quark phase-space information parameterized in a viscous blastwave, we perform Bayesian inference of the shear and bulk viscosities of the QGP at hadronization with a temperature of $T\sim 160$ MeV by analyzing the $\varphi$ and $\Omega$ data in Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}=$ 19.6-200 GeV and Pb+Pb collisions at $\sqrt{s_{\mathrm{NN}}}=$ 2.76 TeV, corresponding to a baryon chemical potential variation from ${\mu }_B\approx 0$ (at $\sqrt{s_{\mathrm{NN}}}=2.76$ TeV) to $200$ MeV (at $\sqrt{s_{\mathrm{NN}}}=19.6$ GeV). We find that the shear viscosity to enthalpy ratio $\eta T/(ϵ+P)$ of the QGP at hadronization decreases as ${\mu }_B$ increases, with $\eta T/(ϵ+P)\approx 0.18$ at ${\mu }_B=0$ and $\eta T/(ϵ+P)\approx 0.08$ at ${\mu }_B=200$ MeV, while the corresponding specific bulk viscosity is essentially constant with $\zeta T/(ϵ+P)=0.02\sim 0.04$ for ${\mu }_B<200$ MeV. Our results suggest that the QGP at hadronization ($T\sim 160$ MeV) with finite baryon density is more close to perfect fluid than that with zero baryon density.

    ↳ nucl-thastro-ph.HEhep-phnucl-exPRC(2024)·4 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.