Mon·Nov 14, 2022Monday·November 14, 2022

1. 01*

   Precision tau physics: Challenge for Theory, on and off the lattice

   Amarjit Soni🇺🇸

   $\tau$ is playing an important role in the current B-physics indications from experiments of lepton flavor universality violations(LFUV). This suggests it be given increasing attention theoretically in the coming years, given also the fact that Belle-II will have much larger data samples to study; similar comments also apply to LHCb as well as ATLAS and CMS. The fact that $\tau$ decays provide valuable information on its spin is an added advantage. This gains special significance if the current indications of new physics are upheld since naturalness arguments then strongly suggest that new physics should be accompanied by new CP-odd phase(s). Moreover, the fact that the $\tau$ mass is around 1.8 GeV,~{\it i.e} a lot less than the B-meson mass makes it much easier candidate for lattice studies in great detail and consequently very likely with greater precision. This should help us test the SM and or BSMs with greater precision as needed.

   hep-phhep-exhep-lat0 citations
2. 02*

   Proton capture in compact dark stars and observable implications

   Boris Betancourt Kamenetskaia🇩🇪 · Anja Brenner🇩🇪 · Alejandro Ibarra🇩🇪 · Chris Kouvaris🇬🇷

   Asymmetric dark matter under certain conditions could form compact star-like objects, which can be searched either through gravitational lensing or by observation of gravitational waves from binaries involving such compact objects. In this paper we analyze possible signatures of such dark stars made of asymmetric dark matter with a portal to the Standard Model. We argue that compact dark stars could capture protons and electrons from the interstellar medium, which then accumulate in the core of the dark star, forming a very hot gas that emits X-rays or $\gamma$-rays. For dark matter parameters compatible with current laboratory constraints, compact dark stars could be sufficiently luminous to be detected at the Earth as point sources in the X-ray or $\gamma$-ray sky.

   hep-phJCAP(2023)·18 citations
3. 03*

   Hunting ewinos and a light scalar of $Z_3$-NMSSM with a bino-like dark matter in top squark decays at the LHC

   AseshKrishna Datta🇮🇳 · Monoranjan Guchait🇮🇳 · Arnab Roy🇮🇳 · Subhojit Roy🇮🇳

   We study the prospects of a simultaneous hunt at the Large Hadron Collider (LHC) of relatively light electroweakinos and a singlet-like scalar of the $Z_3$-symmetric Next-to-Minimal Supersymmetric Standard Model ($Z_3$-NMSSM) in the cascade decays of not so heavy ($\lesssim 1.5$ TeV) top squarks that are produced in pairs at the LHC which characteristically involve the singlet-like states. We work in a scenario where the lightest (next-to-lightest) SUSY particle is bino (singlino)-like with a mass below 100 GeV ($\gtrsim 100$ GeV), whereas a pair of immediately heavier neutralinos and the lighter chargino are higgsino-like with masses in the range $\sim 500$ GeV -- 1 TeV. Further, the singlet-like scalar present in the spectrum provides a funnel for a rapid enough mutual annihilation of the LSP thus making the latter meet the experimental upper bound on its relic abundance. The scenario is motivated by its ability to offer a bino-like dark matter with such a mass unlike what is now disfavored in the MSSM while avoiding the stringent lower bounds from the LHC experiments on the masses of these involved particles and still remaining reasonably `natural'. We find that while a usual cut-based analysis (CBA) on LHC data worth 300 ${\text{fb}}^{-1}$ would be unable to discover such excitations, a multivariate analysis (MVA) can be reasonably sensitive to higgsino-like electroweakinos having masses $\gtrsim 650$ GeV when the lighter top squark has a mass $\gtrsim 1$ TeV. On the other hand, with 3000 ${\text{fb}}^{-1}$ of data these masses become accessible in a CBA while even an MVA on such a data set is unlikely to find these electroweakinos with masses around 1 TeV when the mass of the lighter top squark hits $\sim 1.5$ TeV.

   hep-phJHEP(2023)·12 citations
4. 04*

   Sterile Neutrinos from Dark Matter: A $\nu$ Nightmare?

   Logan Morrison🇺🇸 · Stefano Profumo🇺🇸 · Bibhushan Shakya🇩🇪

   We provide a comprehensive study of observable spectra from dark matter pair-annihilation or decay into sterile (right-handed) neutrinos. This occurs, for instance, in neutrino portal dark matter models, where a sterile neutrino acts as the portal between dark matter and the Standard Model sector. The subsequent decays of right-handed neutrinos produce detectable Standard Model particles, notably photons, positrons, and neutrinos. We study the phenomenology of models where the right-handed neutrino masses are below the GeV scale, as well as models where they are at, or significantly heavier than, the TeV scale. In both instances, and for different reasons, the standard tools, including Monte Carlo simulations, are both inadequate and inaccurate. We present the complete framework to compute the relevant branching ratios for right-handed neutrino decays and the spectra of secondary photons, positrons, and neutrinos for a broad range of dark matter and right-handed neutrino masses. We discuss the general features of such signals, and compare the spectra to standard signals from dark matter annihilation/decay into bottom quarks. Additionally, we provide open source code1 that can be used to compute such spectra. The code is available at https://github.com/LoganAMorrison/blackthorn.

   hep-phastro-ph.HEJHEP(2023)·4 citations
5. 05*

   Resonant $s$-channel dark matter annihilation at NLO

   M. Laine🇨🇭

   Studies of dark matter annihilation through an $s$-channel resonance are often based on recipes such as a narrow width approximation or real intermediate state subtraction. We review a recipe-free formalism that can be implemented at the NLO level in the full theory, and ensures the cancellation of mass singularities. Its basic ingredients can be formulated in the relativistic regime, but we show that the procedure simplifies if we go to the non-relativistic one and assume the presence of kinetic equilibrium. The latter case is illustrated for scalar singlet dark matter with $m_{\mathrm{S}}^{}\simeq 60$ GeV, freezing out at $T\simeq (1-3)$ GeV, re-confirming the viability of this scenario with couplings tiny enough to evade experimental constraints.

   hep-phJHEP(2023)·11 citations
6. 06*

   Hadronic production of ${\Xi }_{bc}$ with the intrinsic heavy-quark content at a fixed-target experiment at the LHC

   Hong-Tai Li🇨🇳 · Xu-Chang Zheng🇨🇳 · Jiang Yan🇨🇳 · Xing-Gang Wu🇨🇳 · Gu Chen🇨🇳

   In this paper, we make a detailed study on the hadronic production of the ${\Xi }_{bc}$ baryon at a fixed target experiment at the LHC (After@LHC). In estimating the production cross sections, the $(g+g)$, $(g+c)$ and $(g+b)$ production mechanisms are considered. For the initial heavy quarks, in addition to the extrinsic component, we also consider the intrinsic component. It is found that the $(g+c)$ and $(g+b)$ production mechanisms give sizable contributions to the ${\Xi }_{bc}$ production, and the $(g+b)$ mechanism dominates the production. The results show that there are about $3.40\times 10^5$ ${\Xi }_{bc}$ events can be produced per year at After@LHC if the integrated luminosity of After@LHC can be up to $2{\mathrm{fb}}^{-1}$ per year. Moreover, the intrinsic heavy quarks can have significant impact on the production, which inversely makes the intrinsic component be possibly tested at the After@LHC.

   hep-phPRD(2022)·5 citations
7. 07*

   Unveiling the effects of multiple soft partonic interactions in pp collisions at $\sqrt{\text{s}}=13.6$ TeV using charged-particle flattenicity

   Antonio Ortiz🇲🇽 · Arvind Khuntia🇨🇿 · Omar Vázquez-Rueda🇺🇸 · Sushanta Tripathy🇮🇹 · Gyula Bencedi🇭🇺 · Suraj Prasad🇮🇳 · Feng Fan🇨🇳

   Event classifiers based either on the charged-particle multiplicity or the event shape have been extensively used in proton-proton (pp) collisions by the ALICE collaboration at the LHC. The use of these tools became very instrumental since the observation of fluid-like behavior in high-multiplicity pp collisions. In particular, the study as a function of the charged-particle multiplicity registered in the forward V0 ALICE detector allowed for the discovery of strangeness enhancement in high-multiplicity pp collisions. However, one drawback of the multiplicity-based event classifiers is that requiring a high charged-particle multiplicity biases the sample towards hard processes like multi-jet final states. These biases make it difficult to perform jet-quenching searches in high-multiplicity pp collisions. In this context, the present paper explores the use of the new event classifier, flattenicity; which uses the multiplicity calculated in the forward pseudorapidity region. To illustrate how this tool works, pp collisions at $\sqrt{s}=13.6$ TeV simulated with PYTHIA~8 are explored. The sensitivity of flattencity to multi-partonic interactions as well as to the ``hardness'' of the collision are discussed. PYTHIA 8 predictions for the transverse momentum spectra of light- and heavy-flavored hadrons as a function of flattenicity are presented.

   hep-phPRD(2023)·28 citations
8. 08*

   Nature of the doubly-charmed tetraquark $T_{cc}^{+}$ in a constituent quark model

   Pablo G. Ortega🇪🇸 · Jorge Segovia🇪🇸 · David R. Entem🇪🇸 · Francisco Fernandez🇪🇸

   The recently discovered $T_{cc}^{+}$ is evaluated as a $D{D}^{\ast }$ molecular structure in the $J^P=1^{+}$ sector. A coupled-channels calculation in charged basis, considering the $D^0{D}^{\ast +}$, $D^{+}{D}^{\ast 0}$ and $D^{\ast 0}{D}^{\ast +}$ channels, is done in the framework of a constituent quark model that successfully described other molecular candidates in the charmonium spectrum such as the $X(3872)$. The $T_{cc}^{+}$ is found as a $D^0{D}^{\ast +}$ molecule ($87\%$) with a binding energy of $387$ keV/c${}^2$ and a width of $81$ keV, in agreement with the experimental measurements. The quark content of the state forces the inclusion of exchange diagrams to treat indistinguishable quarks between the $D$ mesons, which are found to be essential to bind the molecule. The $D^0{D}^0{\pi }^{+}$ line shape, scattering lengths and effective ranges of the molecule are also analyzed, which are found to be in agreement with the LHCb analysis. We search for further partners of the $T_{cc}^{+}$ in other charm and bottom sectors, finding different candidates. In particular, in the charm sector we find a shallow $J^P=1^{+}$ $D^{+}{D}^{\ast 0}$ molecule ($83\%$), dubbed $T_{cc}^{\prime }$, just $1.8$ MeV above the $T_{cc}^{+}$ state. In the bottom sector, we find an isoscalar and an isovector $J^P=1^{+}$ bottom partners, as $B{B}^{\ast }$ molecules lying $21.9$ MeV/c${}^2$ ($I=0$) and $10.5$ MeV/c${}^2$ ($I=1$), respectively, below the $B^0{B}^{\ast +}$ threshold.

   hep-phhep-exPLB(2023)·42 citations
9. 09*

   ${\mathbf{Z}}^{\prime }$-boson dilepton searches and the high-$\mathbf{x}$ quark density

   J. Fiaschi🇬🇧 · F. Giuli🇨🇭 · F. Hautmann🇨🇭 · S. Moch🇩🇪 · S. Moretti🇬🇧

   We study the influence of theoretical systematic uncertainties due to the quark density on LHC experimental searches for $Z^{\prime }$-bosons. Using an approach originally proposed in the context of the ABMP16 PDF set for the high-$x$ behaviour of the quark density, we presents results on observables commonly used to study $Z^{\prime }$ signals in dilepton channels.

   hep-phPLB(2023)·27 citations
10. 10*

    Studying neutrino oscillations at DUNE through dynamical Lorentz symmetry breaking in four-Majorana fermion model

    Susie Kim🇰🇷

    We study the impact of the dynamical Lorentz symmetry breaking induced by the auxiliary gauge fields of neutrino on the oscillations probability at DUNE. The DLSB introduces an alternative energy-momentum relation of the neutrinos and thus results in a new oscillation probability. We extend the previously proposed four-Majorana fermion model that gives rise to DLSB after the type II seesaw mechanism by considering the electron neutrino forward scattering when passing through a medium. Moreover, we incorporate the three-flavor neutrino states, which introduce the CP-violation term inside the oscillation probability. The impact of DLSB parameters around the order of $10^{-2}-10^{-3}$, which are at a strong coupling regime, on the oscillation probability is found to be measurable at DUNE within the 20 years through ${\nu }_e$ and ${\overline{\nu }}_e$ disappearance signals. We also compare the predicted spectra of the DLSB oscillations and the oscillation with the CP-violating term equal to $\pi /2$ to conclude that the presence of DLSB would increase the systematic uncertainty for the measurement of CP-violation at DUNE.

    hep-ph0 citations
11. 11*

    $K_0^{\ast }(1430)$ Twist-2 Distribution Amplitude and $B_s,D_s\to K_0^{\ast }(1430)$ Transition Form Factors

    Dong Huang🇨🇳 · Tao Zhong🇨🇳 · Hai-Bing Fu🇨🇳 · Zai-Hui Wu🇨🇳 · Xing-Gang Wu🇨🇳 · Hong Tong🇨🇳

    Based on the scenario that the $K_0^{\ast }(1430)$ is viewed as the ground state of $s\bar{q}$ or $q\bar{s}$, we study the $K_0^{\ast }(1430)$ leading-twist distribution amplitude (DA) ${\varphi }_{2;K_0^{\ast }}(x,\mu )$ with the QCD sum rules in the framework of background field theory. A more reasonable sum rule formula for $\xi$-moments $⟨{\xi }^n{⟩}_{2;K_0^{\ast }}$ is suggested, which eliminates the influence brought by the fact that the sum rule of $⟨{\xi }_p^0{⟩}_{3;K_0^{\ast }}$ cannot be normalized in whole Borel region. More accurate values of the first ten $\xi$-moments, $⟨{\xi }^n{⟩}_{2;K_0^{\ast }}(n=1,2,\cdots ,10)$, are evaluated. A new light-cone harmonic oscillator (LCHO) model for $K_0^{\ast }(1430)$ leading-twist DA is established for the first times. By fitting the resulted values of $⟨{\xi }^n{⟩}_{2;K_0^{\ast }}(n=1,2,\cdots ,10)$ via the least squares method, the behavior of $K_0^{\ast }(1430)$ leading-twist DA described with LCHO model is determined. Further, by adopting the light-cone QCD sum rules, we calculate the $B_s,D_s\to K_0^{\ast }(1430)$ transition form factors and branching fractions of the semileptonic decays $B_s,D_s\to K_0^{\ast }(1430)\ell {\nu }_{\ell }$. The corresponding numerical results can be used to extract the Cabibbo-Kobayashi-Maskawa matrix elements by combining the relative experimental data in the future.

    hep-phEPJC(2023)·21 citations
12. 12*

    $P_{\psi s}^{\Lambda }(4459)$ and $P_{\psi s}^{\Lambda }(4338)$ as molecular states in $J/\psi \Lambda$ invariant mass spectra

    Jun-Tao Zhu🇨🇳 · Shu-Yi Kong🇨🇳 · Jun He🇨🇳

    Recently, the LHCb Collaboration has reported two strange hidden-charm pentaquark states named $P_{\psi s}^{\Lambda }(4459)$ and $P_{\psi s}^{\Lambda }(4338)$ in the $J/\psi \Lambda$ invariant mass spectra of decays ${\Xi }_b^{-}$$\to$$J/\psi \Lambda K^{-}$ and $B^{-}$$\to$$J/\psi \Lambda \bar{p}$,respectively. In this work, we perform a coupled-channel study of the interactions ${\Xi }_c^{\ast }{\bar{D}}^{\ast }$, ${\Xi }_c^{\prime }{\bar{D}}^{\ast }$, ${\Xi }_c^{\ast }\bar{D}$, ${\Xi }_c{\bar{D}}^{\ast }$, ${\Xi }_c^{\prime }\bar{D}$, ${\Lambda }_c{\bar{D}}_s^{\ast }$, ${\Xi }_c\bar{D}$, ${\Lambda }_c{\bar{D}}_s$, and $\Lambda J/\psi$ in the quasipotential Bethe-Salpeter equation approach to estimate the $J/\psi \Lambda$ invariant mass spectra. With the help of effective Lagrangians, the potential kernel can be constructed by meson exchanges to obtain the scattering amplitudes, from which the poles of the bound states and the invariant mass spectra can be reached. The coupled-channel calculation results in that the width of state ${\Xi }_c{\bar{D}}^{\ast }(1/2^{-})$ is about $18$~MeV and that of state ${\Xi }_c{\bar{D}}^{\ast }(3/2^{-})$ is only about $1.6$~MeV. By comparison with experimental data, it indicates that the structure $P_{\psi s}^{\Lambda }(4459)$ is mainly from the contribution from the ${\Xi }_c{\bar{D}}^{\ast }(1/2^{-})$ state while the role of state ${\Xi }_c{\bar{D}}^{\ast }(3/2^{-})$ cannot be excluded. The line shape of the structure $P_{\psi s}^{\Lambda }(4338)$ can be reproduced roughly by a narrow molecular state from the ${\Xi }_c\bar{D}$ interaction with $J^P$=$1/2^{-}$, which is extremely close to the threshold, with a large interference effect. Besides, an additional state ${\Xi }_c^{\prime }\bar{D}(1/2^{-})$ is suggested to be observed as a dip structure in the $J/\psi \Lambda$ invariant mass spectrum.

    hep-phPRD(2023)·36 citations
13. 13*

    Probing light exotics from a hidden sector at $c$-$\tau$ factories with polarized electron beams

    Dmitry Gorbunov🇷🇺 · Dmitry Kalashnikov🇷🇺

    Future $c$-$\tau$ factories are natural places to study extensions of the Standard Model of particle physics (SM) with new long-lived feebly interacting particles light enough to be produced in electron-positron collisions. We investigate prospects of these machines in exploring such extensions emphasizing the role of polarized beams in getting rid of the SM irreducible background for the missing energy signature. We illustrate this on example of $c$-$\tau$ project in Novosibirsk, where the electron beam is designed to be polarized to achieve much higher sensitivity to hadronic resonances and $\tau$-leptons. We investigate models with hidden photons, with millicharged particles (fermions and scalars), with $Z^{\prime }$ bosons and with axion-like particles. We find that the electron beam polarization of 80\% significantly improves the chances to observe the signal, especially with large statistics. We outline the regions of the model parameter space which can be reached at this factory in one year and in ten years of operation according with the scientific schedule of tuning the energy of colliding beams.

    hep-phPRD(2023)·11 citations
14. 14*

    Hilbert Series, the Higgs Mechanism, and HEFT

    Lukáš Gráf🇺🇸 · Brian Henning🇨🇭 · Xiaochuan Lu🇺🇸 · Tom Melia🇯🇵 · Hitoshi Murayama🇺🇸

    We expand Hilbert series technologies in effective field theory for the inclusion of massive particles, enabling, among other things, the enumeration of operator bases for non-linearly realized gauge theories. We find that the Higgs mechanism is manifest at the level of the Hilbert series, as expected for the partition function of an $S$-matrix that is subject to the Goldstone equivalence theorem. In addition to massive vectors, we detail how other massive, spinning particles can be studied with Hilbert series; in particular, we spell out the ingredients for massive gravity in general spacetime dimensions. Further methodology is introduced to enable Hilbert series to capture the effect of spurion fields acquiring vevs. We apply the techniques to the Higgs Effective Field Theory (HEFT), providing a systematic enumeration of its operator basis. This is achieved both from a direct and a custodial symmetry spurion-based approach; we compare and contrast the two approaches, and our results to those appearing in previous literature.

    hep-phhep-thJHEP(2023)·53 citations
15. 15*

    Wilks's Theorem, Global Fits, and Neutrino Oscillations

    J.M.Hardin🇺🇸

    Tests of models for new physics appearing in neutrino experiments often involve global fits to a quantum mechanical effect called neutrino oscillations. This paper introduces students to methods commonly used in these global fits starting from an understanding of more conventional fitting methods using log-likelihood and ${\chi }^2$ minimization. Specifically, we discuss how the $\Delta {\chi }^2$, which compares the ${\chi }^2$ of the fit with the new physics to the ${\chi }^2$ of the Standard Model prediction, is often interpreted using Wilks's theorem. This paper uses toy models to explore the properties of $\Delta {\chi }^2$ as a test statistic for oscillating functions. The statistics of such models are shown to deviate from Wilks's theorem. Tests for new physics also often examine data subsets for "tension" called the "parameter goodness of fit". In this paper, we explain this approach and use toy models to examine the validity of the probabilities from this test also. Although we have chosen a specific scenario -- neutrino oscillations -- to illustrate important points, students should keep in mind that these points are widely applicable when fitting multiple data sets to complex functions.

    hep-phhep-exEur.J.Phys.(2024)·7 citations
16. 16*

    Zooming in on Multiquark Hadrons within QCD Sum-Rule Approaches

    Wolfgang Lucha🇦🇹 · Dmitri Melikhov🇷🇺 · Hagop Sazdjian🇫🇷

    Aiming at self-consistent descriptions of multiquark hadrons (such as tetraquarks, pentaquarks, hexaquarks) by means of QCD sum rules, we note that the totality of contributions to two-point or three-point correlation functions that involve, respectively, either two or just a single operator capable of interpolating the particular multiquark under study can be straightforwardly disentangled into two disjoint classes defined by unambiguously identifiable members. The first is formed by so-called multiquark-phile contributions which indeed might support multiquarks. In the case of flavour-exotic tetraquarks, by definition composed of four (anti-) quarks of mutually different flavours, a tetraquark-phile contribution has to exhibit two or more gluon exchanges of appropriate topology. The second consists of contributions evidently not bearing any relation to multiquarks; these must be discarded when studying multiquarks by QCD sum rules. The first class only should enter the "multiquark-adequate" QCD sum rules for exotic hadrons.

    hep-phnucl-thEPJ Web Conf.(2022)·0 citations
17. 17*

    The impact of fluctuating initial conditions on bottomonium suppression in 5.02 TeV heavy-ion collisions

    Huda Alalawi🇺🇸 · Jacob Boyd🇺🇸 · Chun Shen🇺🇸 · Michael Strickland🇺🇸

    We compute bottomonium suppression and elliptic flow within the pNRQCD effective field theory using an open quantum systems approach. For the hydrodynamical background, we use 2+1D MUSIC second-order viscous hydrodynamics with IP-Glasma initial conditions and evolve bottom/antibottom quantum wave packets in real time in these backgrounds. We find that the impact of fluctuating initial conditions is small when compared to results obtained using smooth initial conditions. Including the effect of fluctuating initial conditions, we find that the Upsilon(1S) integrated elliptic flow is v_2[1S] = 0.005 +/- 0.002 +/- 0.001, with the first and second variations corresponding to statistical and systematic theoretical uncertainties, respectively.

    hep-phnucl-thPRC(2023)·12 citations
18. 18*

    The meso-inflationary QCD axion

    Michele Redi🇮🇹 · Andrea Tesi🇮🇹

    We study the possibility that the axion Peccei-Quinn symmetry is spontaneously broken after the beginning of inflation. This scenario interpolates between pre-inflationary and post-inflationary axion cosmology with significant phenomenological differences from both. Since the axion is not present at the early stages of inflation large inflationary fluctuations are produced only at scales not constrained by CMB, avoiding the strongest isocurvature constraints. The energy density in isocurvature perturbations at short scales however can be comparable with the adiabatic contribution from misalignment. These large overdensities can lead to the formation of axion mini-clusters and also to constraints from Lyman-$\alpha$ forest and future CMB spectral distortion measurements. If Peccei-Quinn symmetry is broken during the first O(25) e-foldings of inflation no axions are produced from the string network but contributions from the annihilation of domain walls can further boost the abundance. This scenario is minimally realized if the Hubble scale during inflation drops below the Peccei-Quinn symmetry breaking scale but other realizations are possible.

    hep-phastro-ph.COPRD(2023)·47 citations
19. 19*

    Multiple breaking patterns in the Brout-Englert-Higgs effect beyond perturbation theory

    Elizabeth Dobson🇦🇹 · Axel Maas🇦🇹 · Bernd Riederer🇦🇹

    In many BSM theories, especially GUTs, introducing a Brout-Englert-Higgs effect allows for multiple breaking patterns of the gauge symmetry. The possibility to select a particular pattern is usually decisive for the phenomenological viability of a theory. Beyond perturbation theory it is necessary to replace the Brout-Englert-Higgs effect by a manifestly gauge-invariant description. We study the simplest case with multiple breaking patterns, an $\text{SU}(3)$ Yang-Mills theory coupled to a single scalar `Higgs' field in the adjoint representation, on the lattice. We find that only one pattern remains at fixed parameters and gauge-fixing strategy, and that the associated quantum effective potential emerges from a non-trivial interplay of many aspects.

    ↳ hep-lathep-phhep-thAnnals Phys.(2023)·7 citations
20. 20*

    Toward a description of the centrality dependence of the charge balance function in the HYDJET++ model

    A.S. Chernyshov🇷🇺 · G.Kh. Eyyubova🇷🇺 · V.L. Korotkikh🇷🇺 · I.P. Lokhtin🇷🇺 · L.V. Malinina🇷🇺 · S.V. Petrushanko🇷🇺 · A.M. Snigirev🇷🇺 · E.E. Zabrodin🇳🇴

    Data from the Large Hadron Collider on the charge balance function in Pb+Pb collisions at center-of-mass energy 2.76~TeV per nucleon pair are analyzed and interpreted within the framework of the \hydjet++ model. This model allows us to qualitatively reproduce the experimentally observed centrality dependence of the balance function widths at relatively low transverse momentum intervals due to the different charge creation mechanisms in soft and hard processes. However, a fully adequate description of the balance function in these intervals implies an essential modification of the model by including exact charge conservation via the canonical rather than the grand canonical ensemble. A procedure is proposed for introducing charge correlations into the thermal model without changing other model parameters. With increasing transverse momenta, the default model results describe the experimental data much better because the contribution of the soft component of the model is significantly reduced in these transverse momentum intervals. In practical terms, there is a transition to a single source of charge correlations, namely, charge correlations in jets in which exact charge conservation holds at each stage.

    ↳ nucl-thhep-phnucl-exCPC(2023)·8 citations
21. 21*

    New Constraints on Decaying Dark Matter from INTEGRAL/SPI

    S. Fischer🇩🇪 · D. Malyshev🇩🇪 · L. Ducci🇩🇪 · A. Santangelo🇩🇪

    Based on almost 20 years of data collected by the high-resolution spectrometer SPI on board the International Gamma-Ray Astrophysics Laboratory (INTEGRAL) we present constraints on a decaying dark matter particle undergoing a decay into two bodies, at least one of which is a photon, manifesting itself via a narrow line-like spectral feature. Our ON-OFF type analysis of the Milky Way observations allowed us to constrain the lifetime to be $\gtrsim 10^{20}-10^{21}$ yrs for DM particles with masses $40\text{keV}<M_{\text{DM}}<14\text{MeV}$. Within this mass range our analysis also reveals 32 line-like features detected at $\ge 3\sigma$ significance, 29 of which coincide with known instrumental and astrophysical lines. In particular, we report on the detection of the electron-positron annihilation (511 keV) and ${}^{26}$Al (1809 keV) lines with spatial profiles consistent with previous results in the literature. For the particular case of the sterile neutrino DM we report the limits on the mixing angle as a function of sterile neutrino mass. We discuss the dominant impact of systematic uncertainties connected to the strongly time-variable INTEGRAL/SPI instrumental background as well as the ones connected to the uncertainties of MW DM density profile measurements on the derived results.

    ↳ astro-ph.HEhep-phhep-thMNRAS(2023)·15 citations
22. 22*

    Radiation reaction effects in relativistic plasmas -- the electrostatic limit

    Haidar Al-Naseri🇸🇪 · Gert Brodin🇸🇪

    We study the evolution of electrostatic plasma waves, using the relativistic Vlasov equation extended by the Landau-Lifshitz radiation reaction, accounting for the back-reaction due to the emission of single particle Larmor radiation. In particular, the Langmuir wave damping is calculated as a function of wavenumber, initial temperature, and initial electric field amplitude. Moreover, the background distribution function loses energy in the process, and we calculate the cooling rate as a function of initial temperature and initial wave amplitude. Finally, we investigate how the relative magnitude of wave damping and background cooling varies with the initial parameters. In particular, it is found that the relative contribution to the energy loss associated with background cooling decreases slowly with the initial wave amplitude.

    ↳ physics.plasm-phhep-phPRE(2023)·4 citations
23. 23*

    Wilsonian approach to the interaction ${\varphi }^2(i\varphi {)}^{\epsilon }$

    Wen-Yuan Ai🇬🇧 · Jean Alexandre🇬🇧 · Sarben Sarkar🇬🇧

    We study the renormalisation of the non-Hermitian $\mathcal{P}\mathcal{T}$-symmetric scalar field theory with the interaction ${\varphi }^2(i\varphi {)}^{\epsilon }$ using the Wilsonian approach and without any expansion in $\epsilon$. Specifically, we solve the Wetterich equation in the local potential approximation, both in the ultraviolet regime and with the loop expansion. We calculate the scale-dependent effective potential and its infrared limit. The theory is found to be renormalisable at the one-loop level only for integer values of $\epsilon$, a result which is not yet established within the $\epsilon$-expansion. Particular attention is therefore paid to the two interesting cases $\epsilon =1,2$, and the one-loop beta functions for the coupling associated with the interaction $i{\varphi }^3$ and $-{\varphi }^4$ are computed. It is found that the $-{\varphi }^4$ theory has asymptotic freedom in four-dimensional spacetime. Some general properties for the Euclidean partition function and $n$-point functions are also derived.

    ↳ hep-thhep-phquant-phPRD(2023)·7 citations
24. 24*

    A Pop III generated dust screen at z~16

    Fulvio Melia🇺🇸

    The search for alternative cosmological models is largely motivated by the growing discordance between the predictions of LCDM and the ever improving observations, such as the disparity in the value of H_0 measured at low and high redshifts. One model, in particular, known as the R_h=ct universe, has been highly successful in mitigating or removing all of the inconsistencies. In this picture, however, the anisotropies in the cosmic microwave background (CMB) would have emerged at a redshift z ~ 16, rather than via fluctuations in the recombination zone at z~1080. We demonstrate here that a CMB created in the early Universe, followed by scattering through a Pop III generated dust screen, cannot yet be ruled out by the current data. Indeed, the Planck measurements provide a hint of a ~2-4% frequency dependence in the CMB power spectrum, which would be naturally explained as a variation in the optical depth through the dust, but not a Thomson scattering-dominated recombination environment. Upcoming measurements should be able to easily distinguish between these two scenarios, e.g., via the detection of recombination lines at z~1080, which would completely eliminate the dust reprocessing idea.

    ↳ astro-ph.COastro-ph.GAhep-phApJ(2022)·4 citations
25. 25*

    Gravitational Waves from Feebly Interacting Particles in a First Order Phase Transition

    Ryusuke Jinno🇪🇸 · Bibhushan Shakya🇩🇪 · Jorinde van de Vis🇩🇪

    First order phase transitions are well-motivated and extensively studied sources of gravitational waves (GWs) from the early Universe. The vacuum energy released during such transitions is assumed to be transferred primarily either to the expanding bubble walls, whose collisions source GWs, or to the surrounding plasma, producing sound waves and turbulence, which source GWs. In this Letter, we study an alternative possibility that has not yet been considered: the released energy gets transferred primarily to feebly interacting particles that do not form a coherent interacting plasma but simply free-stream individually. We develop the formalism to study the production of GWs from such configurations, and demonstrate that such GW signals have qualitatively distinct characteristics compared to conventional sources and are potentially observable with near-future GW detectors.

    ↳ gr-qcastro-ph.COhep-phPRL(2026)·29 citations

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