Mon·Nov 29, 2021Monday·November 29, 2021

1. 01*

   Stable $Z$-strings with topological polarization in two Higgs doublet model

   Minoru Eto🇯🇵 · Yu Hamada🇯🇵 · Muneto Nitta🇯🇵

   We find that a $Z$-string is stable in a wide range of parameter space of the two Higgs doublet model due to a split into a pair of two topological $Z$-strings with fractional $Z$ fluxes. This configuration, a bound state of the two strings connected by a domain wall, is called a vortex molecule. Although the vortex molecule has no net topological charge, the locally induced topological charge density is polarized, namely distributed positively around one constituent string and negatively around the other constituent string, leading to the stability of the molecule. We numerically show that the vortex molecule is indeed a stable solution of the equation of motions in a much wider parameter space of the model than the usual axially symmetric $Z$-string in the Standard Model and the two Higgs doublet model, although it is not the case for experimental values of the parameters.

   hep-phcond-mat.supr-conhep-thJHEP(2022)·17 citations
2. 02*

   Production of $Z_{cs}$ in $B$ and $B_s$ decay

   Qi Wu🇨🇳 · Dian-Yong Chen🇨🇳 · Wen-Hua Qin🇨🇳 · Gang Li🇨🇳

   In the present work, we investigate the production of $Z_{cs}^{+}$ in $B^{+}$ and $B_s^0$ decay, where $Z_{cs}^{+}$ is assigned as a $D_s^{+}{\bar{D}}^{\ast 0}+D_s^{\ast +}{\bar{D}}^0$ molecular state. By using an effective Lagrangian approach, we evaluate the branching ratio of $B_s^0\to K^{-}{Z}_{cs}^{+}$ and $B^{+}\to \varphi Z_{cs}^{+}$ via the triangle loop mechanism. The estimated branching fractions of $B_s^0\to K^{-}{Z}_{cs}^{+}$ and $B^{+}\to \varphi Z_{cs}^{+}$ are an order of $10^{-4}$ and $10^{-5}$, respectively. The ratio of these two branching fraction is estimated to be about 5, which indicate that the $B_s^0\to K^{\pm }{Z}_{cs}^{\mp }\to K^{+}{K}^{-}J/\psi$ may be a better process of searching $Z_{cs}$ and accessible for further experimental measurement of the Belle II and LHCb collaborations.

   hep-phEPJC(2022)·15 citations
3. 03*

   The reggeometric pomeron and exclusive production of $J/\psi$ and $\psi (2S)$ in ultraperipheral collisions at the LHC

   Laszlo Jenkovszky🇺🇦 · Vladyslav Libov🇺🇦 · Magno V. T. Machado🇧🇷

   By using a Regge-pole model for vector meson production (VMP), successfully describing the HERA data, we analyse the correlation between VMP cross sections in photon-induced reactions at HERA and those in ultra-peripheral collisions at the Large Hadron Collider (LHC). The rapidity distributions of proton-proton collisions at 13~TeV and lead-lead collisions at 2.76 and 5.02 TeV are investigated. The transverse momentum distribution in nuclear coherent vector meson production is also addressed. Predictions for future experiments on production of $J/\psi$ and $\psi (2S)$ are presented.

   hep-phPLB(2022)·14 citations
4. 04*

   Multi-Source Thermal Model Describing Transverse Momentum Spectra of Final-State Particles in High Energy Collisions

   Fu-Hu Liu🇨🇳 · Jia-Yu Chen🇨🇳 · Qiang Zhang🇨🇳

   In this mini review article, the transverse momentum spectra of final-state particles produced in high energy hadron-hadron, hadron-nucleus, and nucleus-nucleus collisions described by the multi-source thermal model at the quark or parton level is summarized. In the model, the participant or contributor quarks or partons are considered to contribute together to the transverse momentum distribution of final-state particles with different modes of contributions. The concrete mode of contribution is generally determined by the difference of azimuthal angles of contributor partons in their emissions.

   hep-phhep-exnucl-exnucl-thAdv.High Energy Phys.(2022)·4 citations
5. 05*

   Higher-order EW corrections in ZZ and ZZj production at the LHC

   Enrico Bothmann🇩🇪 · Davide Napoletano🇮🇹 · Marek Schönherr🇬🇧 · Steffen Schumann🇩🇪 · Simon Luca Villani🇩🇪

   We consider the production of a pair of $Z$ bosons at the LHC and study the inclusion of EW corrections in theoretical predictions at fixed order and based on multijet-merged parton-shower simulations. To this end we present exact NLO EW results for $pp\to e^{+}{e}^{-}{\mu }^{+}{\mu }^{-}$, and, for the first time, for $pp\to e^{+}{e}^{-}{\mu }^{+}{\mu }^{-}j$, and compare them to the EW virtual and NLL Sudakov approximation. We then match the exact NLO EW result to the resummed Sudakov logarithms to achieve an improved NLO EW + NLL ${\text{EW}}_{\text{sud}}^{\text{exp}}$ result. Further, we discuss the inclusion of the above EW corrections in MEPS@NLO event simulations in the framework of the Sherpa event generator. We present detailed phenomenological predictions for inclusive $ZZ$ and $ZZj$ production taking into account the dominant EW corrections through the EW virtual approximation, as well as through (exponentiated) EW Sudakov logarithms.

   hep-phJHEP(2022)·25 citations
6. 06*

   ILC sensitivity for leptophilic scalar dark matter

   Bharti Rawat🇮🇳

   We explore the viability of detecting a leptophilic scalar dark matter at the ILC in a simplified model approach. We present the constraints on the couplings of scalar dark matter with the standard model fermions ensuing from the relic density bounds deduced from the 2018 Planck data. We, then, present the reach of the ILC in terms of $\Lambda$, the scale of the effective theory, by performing a detailed analysis for the $Z$ associated DM pair production (i.e., $e^{+}{e}^{-}\to 2$ jets + $/E_T$, $e^{+}{e}^{-}\to {\mu }^{+}{\mu }^{-}$ + $/E_T$ and $e^{+}{e}^{-}\to e^{+}{e}^{-}$ + $/E_T$). We present the results for various run scenarios as 3-$\sigma$ contours in the $m_{\varphi }-\Lambda$ plane. We also analyze the effect of beam polarization on the sensitivity of this search. We find that for the process with two hadronic jets in the final state, ILC can probe $\Lambda$ up to 1.76 TeV for $\sqrt{s}=1$ TeV that can further enhance to 1.99 TeV, after the inclusion of polarization effects.

   hep-phJ.Phys.G(2024)·1 citation
7. 07*

   $D^{+}{D}^{-}$ hadronic atom and its production in $pp$ and $p\bar{p}$ collisions

   Pan-Pan Shi🇨🇳 · Zhen-Hua Zhang🇨🇳 · Feng-Kun Guo🇨🇳 · Zhi Yang🇨🇳

   There must be Coulomb bound states of a pair of hadrons, which are stable against the strong interaction, with opposite electric charges. Such bound states are hadronic atoms. We study the properties and the production of the ground-state $D^{+}{D}^{-}$ hadronic atom $A_{D^{+}{D}^{-}}$, called dionium, with quantum numbers $J^{PC}=0^{++}$. Using a nonrelativistic effective field theory for the $D^0{\bar{D}}^0$-$D^{+}{D}^{-}$ coupled-channel system, the mass of the ground-state dionium is predicted to be $(3739.3\pm 0.1)\text{MeV}$, with the binding energy reduced by about 10% compared to the Coulomb binding energy due to the strong interaction. Its width for the decay into the neutral $D^0{\bar{D}}^0$ channel is predicted to be $1.8_{-0.6}^{+1.4}$ keV using lattice inputs for the $D\bar{D}$ strong interaction. The cross section for the inclusive prompt production of the dionium at CMS and LHCb and that for the direct production $p\bar{p}\to A_{D^{+}{D}^{-}}$ at PANDA are estimated at an order-of-magnitude level. In particular, we expect that $\mathcal{O}(10^3\sim 10^5)$ events of the reaction chain $p\bar{p}\to A_{D^{+}{D}^{-}}\to D^0{\bar{D}}^0\to K^{-}{\pi }^{+}{K}^{+}{\pi }^{-}$ can be collected at PANDA, and valuable information on the charmed meson interaction and on understanding charmoniumlike states will be obtained.

   hep-phhep-exnucl-exnucl-thPRD(2022)·13 citations
8. 08*

   Bottomonium observables in an open quantum system using the quantum trajectories method

   Peter Vander Griend🇩🇪

   We solve the Lindblad equation describing the Brownian motion of a Coulombic heavy quark-antiquark pair in a strongly coupled quark gluon plasma using the Monte Carlo wave function method. The Lindblad equation has been derived in the framework of pNRQCD and fully accounts for the quantum and non-Abelian nature of the system. The hydrodynamics of the plasma is realistically implemented through a 3+1D dissipative hydrodynamics code. We compute the bottomonium nuclear modification factor and elliptic flow and compare with the most recent LHC data. The computation does not rely on any free parameter, as it depends on two transport coefficients that have been evaluated independently in lattice QCD. Our final results, which include late-time feed down of excited states, agree well with the available data from LHC 5.02 TeV PbPb collisions.

   hep-phnucl-exnucl-thphysics.comp-phEPJ Web Conf.(2022)·4 citations
9. 09*

   On phase-space integrals with Heaviside functions

   Daniel Baranowski🇩🇪 · Maximilian Delto🇩🇪 · Kirill Melnikov🇩🇪 · Chen-Yu Wang🇩🇪

   We discuss peculiarities that arise in the computation of real-emission contributions to observables that contain Heaviside functions. A prominent example of such a case is the zero-jettiness soft function in SCET, whose calculation at next-to-next-to-next-to-leading order in perturbative QCD is an interesting problem. Since the zero-jettiness soft function distinguishes between emissions into different hemispheres, its definition involves $\theta$-functions of light-cone components of emitted soft partons. This prevents a direct use of multi-loop methods, based on reverse unitarity, for computing the zero-jettiness soft function in high orders of perturbation theory. We propose a way to bypass this problem and illustrate its effectiveness by computing various non-trivial contrbutions to the zero-jettiness soft function at NNLO and N3LO in perturbative QCD.

   hep-phJHEP(2022)·26 citations
10. 10*

    Three-loop helicity amplitudes for diphoton production in gluon fusion

    Piotr Bargiela🇬🇧 · Fabrizio Caola🇬🇧 · Andreas von Manteuffel🇺🇸 · Lorenzo Tancredi🇩🇪

    We present a calculation of the helicity amplitudes for the process $gg\to \gamma \gamma$ in three-loop massless QCD. We employ a recently proposed method to calculate scattering amplitudes in the 't Hooft-Veltman scheme that reduces the amount of spurious non-physical information needed at intermediate stages of the computation. Our analytic results for the three-loop helicity amplitudes are remarkably compact, and can be efficiently evaluated numerically. This calculation provides the last missing building block for the computation of NNLO QCD corrections to diphoton production in gluon fusion.

    hep-phhep-thJHEP(2022)·58 citations
11. 11*

    Out-of-Equilibrium Photon Production in the Late Stages of Relativistic Heavy-Ion Collisions

    Anna Schäfer · Oscar Garcia-Montero · Jean-François Paquet · Hannah Elfner · Charles Gale

    In this work, we assess the importance of non-equilibrium dynamics in the production of photons from the late stages of relativistic heavy-ion collisions. The p${}_{\mathrm{T}}$-differential spectra and $v_2$ of photons from the late hadronic stage are computed within a non-equilibrium hadron transport approach, and compared to the results of a local equilibrium evolution using ideal relativistic hydrodynamics. It is found that non-equilibrium dynamics enhance the late-stage photon production at low p${}_{\mathrm{T}}$ and decreases it at higher p${}_{\mathrm{T}}$ compared to the estimate from hydrodynamics. This same comparison points to a significant increase in the momentum anisotropies of these photons due to non-equilibrium dynamics. Once combined with photons produced above the particlization temperature in the hydrodynamics evolution, the differences between the two approaches appear modest in what concerns the p${}_{\mathrm{T}}$ differential spectra, but are clearly noticeable at low p${}_{\mathrm{T}}$ for the elliptic flow: non-equilibrium dynamics enhance the photon $v_2$ below p${}_{\mathrm{T}}$ $\approx 1.4$ GeV.

    hep-phnucl-thPRC(2022)·26 citations
12. 12*

    Heavy-Light Susceptibilities in a Strongly Coupled Quark-Gluon Plasma

    Shuai Y. F. Liu🇨🇳 · Ralf Rapp🇺🇸

    Quark number susceptibilities as computed in lattice QCD are commonly believed to provide insights into the microscopic structure of QCD matter, in particular its degrees of freedom. We generalize a previously constructed partonic $T$-matrix approach to finite chemical potential to calculate various susceptibilities, in particular for configurations containing a heavy charm quark. At vanishing chemical potential and moderate temperatures, this approach predicts large collisional widths of partons generated by dynamically formed hadronic resonance states which lead to transport parameters characteristic for a strongly coupled system. The quark chemical potential dependence is implemented into the propagators and the in-medium color potential, where two newly introduced parameters for the thermal and screening masses are fixed through a fit to the baryon number susceptibility, ${\chi }_2^B$. With this setup, we calculate heavy-light susceptibilities without further tuning; the results qualitatively agree with the lattice-QCD (lQCD) data for both ${\chi }_{11}^{uc}$ and ${\chi }_{22}^{uc}$. This implies that the lQCD results are compatible with a significant content of broad $D$-meson and charm-light diquark bound states in a moderately hot QGP.

    hep-phhep-latnucl-exnucl-thPRC(2022)·10 citations
13. 13*

    Learning New Physics from an Imperfect Machine

    Raffaele Tito d'Agnolo🇫🇷 · Gaia Grosso🇨🇭 · Maurizio Pierini🇨🇭 · Andrea Wulzer🇮🇹 · Marco Zanetti🇮🇹

    We show how to deal with uncertainties on the Standard Model predictions in an agnostic new physics search strategy that exploits artificial neural networks. Our approach builds directly on the specific Maximum Likelihood ratio treatment of uncertainties as nuisance parameters for hypothesis testing that is routinely employed in high-energy physics. After presenting the conceptual foundations of our method, we first illustrate all aspects of its implementation and extensively study its performances on a toy one-dimensional problem. We then show how to implement it in a multivariate setup by studying the impact of two typical sources of experimental uncertainties in two-body final states at the LHC.

    hep-phEPJC(2022)·56 citations
14. 14*

    Linear power corrections for two-body kinematics in the $q_T$ subtraction formalism

    Luca Buonocore🇨🇭 · Stefan Kallweit🇮🇹 · Luca Rottoli🇨🇭 · Marius Wiesemann🇩🇪

    Transverse-momentum cuts on undistinguished particles in two-body final states induce an enhanced sensitivity to low momentum scales. This undesirable feature, which ultimately leads to an instability of the fixed-order series, poses additional challenges to non-local subtraction schemes. In this letter, we address this issue for general colour-singlet processes within the $q_T$-subtraction formalism, focussing on neutral-current Drell-Yan production. We present a simple procedure to reduce the dependence on the slicing parameter from linear to quadratic, by accounting for the linear power corrections through an appropriate recoil prescription. We observe a dramatical improvement of the numerical convergence and a reduction of the systematic uncertainties. We also discuss how a linear dependence in $q_T$ can be avoided for Drell-Yan production by using staggered cuts, which, to the best of our understanding, could be used in experimental analyses. We show that our approach can be successfully applied also to on-shell $ZZ$ production. We finally study diphoton production and verify that our approach is insufficient to capture the linear power corrections introduced by the isolation procedure. The recoil prescription is available in version 2.1 of MATRIX.

    hep-phhep-exPLB(2022)·32 citations
15. 15*

    Freeze-in, glaciation, and UV sensitivity from light mediators

    Nicolas Fernandez🇺🇸 · Yonatan Kahn🇺🇸 · Jessie Shelton🇺🇸

    Dark matter (DM) freeze-in through a light mediator is an appealing model with excellent detection prospects at current and future experiments. Light mediator freeze-in is UV-insensitive insofar as most DM is produced at late times, and thus the DM abundance does not depend on the unknown early evolution of our universe. However the final DM yield retains a dependence on the initial DM population, which is usually assumed to be exactly zero. We point out that in models with light mediators, the final DM yield will also depend on the initial conditions assumed for the light mediator population. We describe a class of scenarios we call "glaciation" where DM freezing in from the SM encounters a pre-existing thermal bath of mediators, and study the dependence of the final DM yield on the initial temperature of this dark radiation bath. To compute DM scattering rates in this cosmology, we derive for the first time an exact integral expression for the Boltzmann collision term describing interactions between two species at different temperatures. We quantify the dependence of the DM yield on the initial dark temperature and find that it can be sizeable in regions near the traditional (zero initial abundance) freeze-in curve. We generalize the freeze-in curve to a glaciation band, which can extend as much as an order of magnitude below the traditional freeze-in direct detection target, and point out that the DM phase space distribution as well as the yield can be strongly dependent on initial conditions.

    hep-phastro-ph.COJHEP(2022)·23 citations
16. 16*

    Multi-lepton probes of new physics and lepton-universality in top-quark interactions

    Yoav Afik🇨🇭 · Shaouly Bar-Shalom🇮🇱 · Kuntal Pal🇺🇸 · Amarjit Soni🇺🇸 · Jose Wudka🇺🇸

    We explore the sensitivity to new physics (NP) in the associated production of top-quarks with leptons $pp\to t\bar{t}{\ell }^{+}{\ell }^{-}$, which leads to the multi-leptons signals $pp\to n\ell +\mathtt{jets}+/E_T$, where $n=2,3,4$. The NP is parameterized via 4-Fermi effective $t\bar{t}{\ell }^{+}{\ell }^{-}$ contact interactions of various types, which are generated by multi-TeV heavy scalar, vector or tensor exchanges in $t\bar{t}\to {\ell }^{+}{\ell }^{-}$; we focus on the case of $\ell =e,\mu$. We match the 4-Fermi $tt\ell \ell$ terms to the SMEFT operators and also give examples of specific underlying heavy physics that can generate such terms. Analysis of the SM signals and corresponding backgrounds shows that the di-lepton and tri-lepton channels are much better probes of the effective $t\bar{t}{\ell }^{+}{\ell }^{-}$ 4-Fermi terms than the four-lepton one at the 13 TeV LHC. Therefore, the best sensitivity is obtained in the di- and tri-lepton channels, for which the dominant background $pp\to t\bar{t}$ and $pp\to WZ$, respectively, can be essentially eliminated after applying the $2\ell$ and $3\ell$ selections and a sufficiently high invariant mass selection for the opposite sign same flavor (OSSF) lepton-pair. We explore two cases: lepton flavor universal (LFU) NP where the $ttee$ and $tt\mu \mu$ contact interactions are of same size and LFU violating (LFUV) NP, where the scale of the $tt\mu \mu$ terms is assumed to be much lower. We show that in both cases it is possible to obtain new 95\% CL bounds on the scale of the $tt\ell \ell$ contact interactions at the level $\Lambda \gtrsim 2-3$ TeV, which are considerably tighter than the current bounds on these 4-Fermi terms.

    hep-phhep-exNPB(2022)·23 citations
17. 17*

    Constraints on the fermionic dark matter from observations of neutron stars

    V. Sagun🇵🇹 · E. Giangrandi🇵🇹 · O. Ivanytskyi🇵🇱 · I. Lopes🇵🇹 · K. A. Bugaev🇺🇦

    We study an impact of asymmetric fermionic dark matter on neutron star properties, including tidal deformability, mass, radius, etc. We present the conditions at which dark matter particles tend to form a compact structure in a core of the star or create an extended halo around it. We show that compact core of dark matter leads to a decrease of the total gravitational mass and tidal deformability compared to a pure baryonic star, while presence of a dark matter halo increases those observable quantities. By imposing an existing astrophysical and gravitational wave constraints set by LIGO/Virgo Collaboration together with the recent results on the spatial distribution of dark matter in the Milky Way we determine a new upper limit on the mass and fraction of dark matter particles inside compact stars. Furthermore, we show that the formation of an extended halo around a NS is incompatible with the GW170817 tidal deformability constraint.

    ↳ astro-ph.HEhep-phnucl-thPoS(2022)·19 citations
18. 18*

    Quark-gluon vertex with 2 flavours of O(a) improved Wilson fermions

    Ayse Kızılersü🇦🇺 · Orlando Oliveira🇵🇹 · Paulo Silva🇵🇹 · Jon-Ivar Skullerud🇮🇪 · André Sternbeck🇩🇪

    We study the Landau-gauge quark-gluon vertex with 2 flavours of O(a)improved Wilson fermions, for several lattice spacings and quark masses. In the limit of vanishing gluon momentum, we find that all nonzero form factors have a significant infrared strength, and that the leading form factor lambda_1, multiplying the tree-level vertex structure, is significantly enhanced in the infrared compared to the quenched case. We find that all form factors are further enhanced in the infrared as the chiral and continuum limits are approached.

    ↳ hep-lathep-phPoS(2022)·6 citations
19. 19*

    Collectivity of $J/\psi$ Mesons in Heavy-Ion Collisions

    Min He🇨🇳 · Biaogang Wu🇺🇸 · Ralf Rapp🇺🇸

    The production of $J/\psi$ mesons in heavy-ion collisions at the Large Hadron Collider is believed to be dominated by the recombination of charm and anti-charm quarks in a hot QCD medium. However, measurements of the elliptic flow ($v_2$) of $J/\psi$ mesons in these reactions are not well described by existing calculations of $J/\psi$ recombination for transverse momenta $p_T\ge$4 GeV. Here, we revisit these calculations in two main aspects. By employing the resonance recombination model, we implement distribution functions of charm quarks transported through the quark-gluon plasma using state-of-the-art Langevin simulations, and we account for the space-momentum correlations of the diffusing charm and anti-charm quarks in the hydrodynamically expanding fireball. These improvements extend the relevance of the recombination processes to substantially larger momenta than before. In addition, we revisit the suppression of the primordially produced $J/\psi$ mesons by propagating them through the same hydrodynamic medium, leading to a marked increase of the $v_2$ of this component over previous estimates. Combining these developments into a calculation of the $p_T$-dependent nuclear modification factor and $v_2$ of inclusive $J/\psi$ production in semi-central Pb-Pb collisions at the LHC, we find a good description of the experimental results by the ALICE collaboration. Our results thus resolve the above-mentioned $v_2$ puzzle and imply the relevance of recombination processes for $p_T$'s of up to $\sim$8 GeV.

    ↳ nucl-thhep-phnucl-exPRL(2022)·53 citations
20. 20*

    Viscous absorption of ultra-high-frequency gravitons

    Massimo Giovannini🇨🇭

    The high-frequency gravitons can be absorbed by the first and second viscosities of the post-inflationary plasma as the corresponding wavelengths reenter the Hubble radius prior to big-bang nucleosynthesis. When the total sound speed of the medium is stiffer than radiation the rate of expansion still exceeds the shear rate but the bulk viscosity is not negligible. Depending on the value of the entropy density at the end of inflation the spectral energy density of the relic gravitons gets modified in comparison with the inviscid result when the frequency ranges between the kHz band and the GHz region. In the nHz domain the spectrum inherits a known suppression due to neutrino free-streaming but also a marginal spike potentially caused by a sudden outbreak of the bulk viscosity around the quark-hadron phase transition, as suggested by the hadron spectra produced in the collisions of heavy ions.

    ↳ hep-thastro-ph.COgr-qchep-phPLB(2022)·0 citations
21. 21*

    Direct Detection Constraints on Blazar-Boosted Dark Matter

    Jin-Wei Wang🇮🇹 · Alessandro Granelli🇮🇹 · Piero Ullio🇮🇹

    We explore the possibility that relativistic protons in the extremely powerful jets of blazars may boost via elastic collisions the dark matter particles in the surroundings of the source to high energies. We concentrate on two sample blazars, TXS 0506+056 - towards which IceCube recently reported evidence for a high-energy neutrino flux - and BL Lacertae, a representative nearby blazar. We find that the dark matter flux at Earth induced by these sources may be sizable, larger than the flux associated with the analogous process of dark matter boosted by galactic cosmic rays, and relevant to access direct detection for dark matter particle masses lighter than 1 GeV. From the null detection of a signal by XENON1T, MiniBooNE, and Borexino, we derive limits on dark matter-nucleus spin-independent and spin-dependent cross sections which, depending on the modelization of the source, improve on other currently available bounds for light dark matter candidates of 1 up to 5 orders of magnitude.

    ↳ astro-ph.HEhep-phPRL(2022)·95 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.