Fri·Sep 9, 2022Friday·September 9, 2022

1. 01*

   A new approach to semi-leptonic tags in $B$-meson semi-invisible decays

   Gaetano de Marino🇫🇷 · Diego Guadagnoli🇫🇷 · Chan Beom Park🇰🇷 · Karim Trabelsi🇫🇷

   Kinematic variables designed for pairwise decays to partly undetected final states -- a prominent example being $M_{T2}$ and its Lorentz-invariant version $M_2$ -- have been extensively deployed in high-$p_T$ collider searches. A new range of potential applications at flavour facilities -- where $B$ mesons or $\tau$ leptons are also pairwise produced -- was recently proposed. One general challenge in these decays arises if both the signal parent and the 'other' parent, often used as a tag, decay semi-invisibly. In such cases, which notably include semi-leptonic tags, signal identification is generally hindered by the ensuing lack of knowledge of the signal-parent boost. $M_2$ helps precisely to overcome this challenge, and allows to leverage the otherwise superior efficiency of semi-leptonic decays. Our strategy rests on two novel constraints that can be imposed on $M_2$. The first is that of the known mass of the decaying-parent mass squared which, in connection with other constraints, gives rise to $M_{2sB}$. The second is on the flight direction of the signal parent, often well reconstructed at facilities with high vertexing capabilities such as Belle II and LHCb. This constraint gives rise to the $M_{2V}$ variable, that can be used even at facilities where the collision energy is not known. We test these ideas in a decay of great current interest in the context of the persistent discrepancies in $B$ decays, namely $B\to K\tau \mu$. We find that a bare-bones application of $M_{2sB}$ leads, alone, to an improvement that is already halfway between the current approach and the "truth-level" semi-leptonic case. Ceteris paribus -- in particular statistics -- our approach thus makes semi-leptonic tags competitive with fully reconstructed hadronic tags.

   hep-phhep-exPRD(2023)·4 citations
2. 02*

   $B$ Anomalies and Dark Matter in an $L_{\mu }-L_{\tau }$ Model with General Kinetic Mixing

   Douglas Tuckler🇨🇦

   We revisit the $L_{\mu }-L_{\tau }$ extension of the Standard Model that can simultaneously address anomalies in semileptonic $B$ meson decays and the nature of dark matter (DM). In the region favored by the $B$ anomalies, this scenario is excluded by a combination of low-energy flavor constraints and stringent DM direct detection constraints if the kinetic mixing between $Z^{\prime }$ gauge boson and the photon vanishes at high energy scales, since this leads to a sizable coupling between DM and the SM in low-momentum scattering processes. However, this is no longer the case if the kinetic mixing vanishes at low energy scales instead. In this scenario, the low-momentum DM scattering rate can be suppressed and constraints from direct detection experiments can be substantially relaxed. As a result, we find a re-opening of the region of parameter space where the $B$ anomalies and DM can be simultaneously explained.

   hep-ph3 citations
3. 03*

   T-odd Leading-Twist Quark TMDs at Small $x$

   Yuri V. Kovchegov🇺🇸 · M. Gabriel Santiago🇺🇸

   We study the small-$x$ asymptotics of the flavor non-singlet T-odd leading-twist quark transverse momentum dependent parton distributions (TMDs), the Sivers and Boer-Mulders functions. While the leading eikonal small-$x$ asymptotics of the quark Sivers function is given by the spin-dependent odderon, we are interested in revisiting the sub-eikonal correction considered by us earlier. We first simplify the expressions for both TMDs at small Bjorken $x$ and then construct small-$x$ evolution equations for the resulting operators in the large-$N_c$ limit, with $N_c$ the number of quark colors. For both TMDs, the evolution equations resum all powers of the double-logarithmic parameter ${\alpha }_s{\ln }^2(1/x)$, where ${\alpha }_s$ is the strong coupling constant, which is assumed to be small. Solving these evolution equations numerically (for the Sivers function) and analytically (for the Boer-Mulders function) we arrive at the following leading small-$x$ asymptotics of these TMDs at large $N_c$: \begin{align} f_{1 \: T}^{\perp \: NS} (x \ll 1 ,k_T^2) & = C_O (x, k_T^2) \, \frac{1}{x} + C_1 (x, k_T^2) \, \left( \frac{1}{x} \right)^{3.4 \, \sqrt{\frac{\alpha_s \, N_c}{4 \pi}}} , \notag \\ h_1^{\perp \, \textrm{NS}} (x \ll 1, k_T^2) & = C (x, k_T^2) \left( \frac{1}{x} \right)^{-1}. \notag \end{align} The functions $C_O(x,k_T^2)$, $C_1(x,k_T^2)$, and $C(x,k_T^2)$ can be readily obtained in our formalism: they are mildly $x$-dependent and do not strongly affect the power-of-$x$ asymptotics shown above. The function $C_O$, along with the $1/x$ factor, arises from the odderon exchange. For the sub-eikonal contribution to the quark Sivers function (the term with $C_1$), our result shown above supersedes the one obtained in our previous work due to the new contributions identified recently.

   hep-phhep-exnucl-exnucl-thJHEP(2022)·42 citations
4. 04*

   Extending the Predictive Power of Perturbative QCD Using the Principle of Maximum Conformality and Bayesian Analysis

   Jian-Ming Shen🇨🇳 · Zhi-Jian Zhou🇨🇳 · Sheng-Quan Wang🇨🇳 · Jiang Yan🇨🇳 · Zhi-Fei Wu🇨🇳 · Xing-Gang Wu🇨🇳 · Stanley J. Brodsky🇺🇸

   In addition to the evaluation of high-order loop contributions, the precision and predictive power of perturbative QCD (pQCD) predictions depends on two important issues: (1) how to achieve a reliable, convergent fixed-order series, and (2) how to reliably estimate the contributions of unknown higher-order terms. The recursive use of renormalization group equation, together with the Principle of Maximum Conformality (PMC), eliminates the renormalization scheme-and-scale ambiguities of the conventional pQCD series. The result is a conformal, scale-invariant series of finite order which also satisfies all of the principles of the renormalization group. In this paper we propose a novel Bayesian-based approach to estimate the size of the unknown higher order contributions based on an optimized analysis of probability distributions. We show that by using the PMC conformal series, in combination with the Bayesian analysis, one can consistently achieve high degree of reliability estimates for the unknown high order terms. Thus the predictive power of pQCD can be greatly improved. We illustrate this procedure for two pQCD observables: $R_{e^{+}{e}^{-}}$ and $R_{\tau }$, which are each known up to four loops in pQCD. Numerical analyses confirm that by using the scale-independent and more convergent PMC conformal series, one can achieve reliable Bayesian probability estimates for the unknown higher-order contributions.

   hep-phEPJC(2023)·20 citations
5. 05*

   Photoproduction of $e^{+}{e}^{-}$ pair in a Coulomb field near the threshold

   P.A. Krachkov🇷🇺 · R.N. Lee🇷🇺 · A.I. Milstein🇷🇺

   We consider the electron-positron pair production by a photon in Coulomb field near threshold. We obtain the analytical results for the particle energy spectrum and angular distribution exactly in the parameter $Z{e}^2/\hslash v$. We show that Furry-Sommerfeld-Maue approximation for the wave functions used by Nishina, Tomonaga and Sakata is not sufficient and leads to wrong results.

   hep-phphysics.atom-phPLB(2022)·3 citations
6. 06*

   Bracketing the direct detection exclusion plot for a WIMP of spin one half in non-relativistic effective theory

   Sunghyun Kang (Sogang U. and CQUeST)🇰🇷 · Injun Jeong (Sogang U. and CQUeST)🇰🇷 · Stefano Scopel (Sogang U. and CQUeST)🇰🇷

   Assuming a standard Maxwellian velocity distribution for the WIMPs in the halo of our Galaxy we use the null results of an exhaustive set of 9 direct detection experiments to calculate the maximal variation of the exclusion plot for each Wilson coefficient of the most general Galilean-invariant effective Hamiltonian for a WIMP of spin one half due to interferences. We consider 56 Wilson coefficients $c_i^{p,n}$ and ${\alpha }_i^{n,p}$ for WIMP-proton and WIMP-neutron contact interactions ${\mathcal{O}}_i^{p,n}$ and the corresponding long range interaction ${\mathcal{O}}_i^{p,n}/q^2$, parameterized by a massless propagator $1/q^2$. For each coupling we provide a different exclusion plot when the following set of operators is allowed to interfere: proton-neutron, i.e. $c_i^p$-$c_i^n$ or ${\alpha }_i^p$-${\alpha }_i^n$; contact-contact or long range-long range, i.e. $c_i^{p,n}$-$c_j^{p,n}$ or ${\alpha }_i^{p,n}$-${\alpha }_j^{p,n}$; contact-long range, i.e. $c_i^{p,n}$-${\alpha }_j^{p,n}$. For each of the 56 Wilson coefficients $c_i^{p,n}$ and ${\alpha }_j^{p,n}$ and for the largest number of interfering operators the exclusion plot variation can reach 3 orders of magnitude and reduces to a factor as small as a few for the Wilson coefficients of the effective interactions where the WIMP couples to the nuclear spin, thanks to the combination of experiments using proton-odd and neutron-odd targets. Some of the conservative bounds require an extremely high level of cancellation, putting into question the reliability of the result. We analyze this issue in a systematic way, showing that it affects some of the couplings driven by the operators ${\mathcal{O}}_1$, ${\mathcal{O}}_3$, ${\mathcal{O}}_{11}$, ${\mathcal{O}}_{12}$ and ${\mathcal{O}}_{15}$, especially when interferences among contact and long range interactions are considered.

   hep-phastro-ph.COhep-exAstropart.Phys.(2023)·3 citations
7. 07*

   Analysis of the exotic resonances in the systems $QQ\bar{q}\bar{q}$ and $Qq\bar{Q}\bar{q}$ with the extended recoupling model

   Yu. A. Simonov🇷🇺

   The phenomenon of a narrow peak X(3875), discovered recently by the LHCb in the $D^{\ast }D$ system, and the absence of resonances in the $D_s{D}_s$ and $D_s^{\ast }{D}_s^{\ast }$ systems is discussed within the new extended version of the Recoupling Model, where the resonance is the result of infinite recoupling transitions of confining strings between quarks and antiquarks. We show that existence of the resonance in the $D^{\ast }D$ and its absence in $D_s{D}_s$ and $D_s^{\ast }{D}_s^{\ast }$ systems are the natural results of the Recoupling Mechanism. The application of this mechanism to the $D{\bar{D}}^{\ast }$ system allows to obtain the resonance $Z_c(3900)$ with larger width in agreement with experimental data.

   hep-phPhys.Atom.Nucl.(2023)·2 citations
8. 08*

   Large-rapidity ridge correlations from Color Glass Condensate

   Donghai Zhang🇨🇳 · Yeyin Zhao🇨🇳 · Mingmei Xu🇨🇳 · Yuanfang Wu🇨🇳

   Within the Color Glass Condensate (CGC) effective field theory, considering the violation of boost invariance of the rapidity distribution, we correct the normalization scheme of the longitudinal rapidity ridge correlations. After this correction, the large-rapidity ridge correlation rebounds after bottoming, consistent with the observed data from the CMS detector. It is also found that the correlation rebound appears around the sum of the saturation momentum of the projectile and target, and moves to larger rapidities at higher collision energies. These features directly result from the saturation and the quantum evolution of gluons within the framework of the CGC.

   hep-phPRD(2023)·1 citation
9. 09*

   The $D^{\ast }/D$ ratio in heavy ion collisions

   L. M. Abreu🇧🇷 · F. S. Navarra🇧🇷 · H. P. L. Vieira

   In this work we study the $D^{\ast }$ and $D$ multiplicities and how they change during the hadron gas phase of heavy ion collisions. With the help of an effective Lagrangian formalism, we calculate the production and absorption cross sections of the $D^{\ast }$ and $D$ mesons in a hadronic medium. We compute the time evolution of the abundances and the ratio $D^{\ast }/D$. They are approximately constant in time. Also, assuming a Bjorken type cooling and using an empirical relation between the freeze-out temperature and the central multiplicity density, we estimate $D^{\ast }/D$ as a function of $dN/d\eta (\eta =0)$, which represents the system size. We find that, while the number of $D^{\ast }$'s and $D$'s grows significantly with the system size, their ratio remains approximately constant. This prediction can be compared with future experimental data. Our results suggest that the charm meson interactions in the hadron gas do not change their multiplicities and consequently these mesons are close to chemical equilibrium.

   hep-phPRD(2022)·6 citations
10. 10*

    Mass-derivative relations and unitarity constraints for $CP$ asymmetries at finite temperature

    Tomáš Blažek🇸🇰 · Peter Maták🇸🇰 · Viktor Zaujec🇸🇰

    Within the seesaw type-I leptogenesis, we formulate $CPT$ and unitarity constraints for the equilibrium reaction rate $CP$ asymmetries and consider thermal mass and quantum statistics. We demonstrate that including higher-order perturbative corrections in the classical Boltzmann equation remarkably induces quantum effects into the kinetic theory.

    hep-phJCAP(2022)·6 citations
11. 11*

    Production of $T_{cc}^{+}$ in heavy ion collisions

    L. M. Abreu🇧🇷 · F. S. Navarra🇧🇷 · M. Nielsen🇧🇷 · H. P. L. Vieira🇧🇷

    We study the production of heavy multiquark states in the heavy ion collisions performed at the LHC. We assume that they are produced at the end of the quark-gluon plasma phase and then interact with light hadrons during the hadron gas phase. We use the coalescence model to compute the initial multiplicities and effective Lagrangians to describe the interactions. We find that the initial multiplicity of molecules is two orders of magnitude larger than that of tetraquarks. The interactions in the hadron gas reduce the number of molecules and increase the number of tetraquarks by a factor two in each case. At kinetic freeze-out, the difference is still very large.

    hep-ph6 citations
12. 12*

    $M_W$, Dark Matter and $a_{\mu }$ in the NMSSM

    Florian Domingo🇩🇪 · Ulrich Ellwanger🇫🇷 · Cyril Hugonie🇫🇷

    We study regions in the parameter space of the NMSSM which are able to simultaneously explain the current measured values for the $W$ mass $M_W$ and the muon anomalous magnetic moment $a_{\mu }$, and provide a dark matter relic density consistent with the observations as well as constraints from detection experiments. The corresponding regions feature light charginos, sleptons and staus in the 100-800~GeV range, at least some of them with masses below 150~GeV such that the electroweakly-interacting SUSY particles generate sufficiently large contributions to $M_W$. The LSP is always singlino-like with a mass below 140~GeV, and could possibly remain invisible even at future detection experiments. Decays of electroweak sparticles proceed through cascades via staus and/or sleptons which makes their detection challenging. We propose benchmark points for future searches of such sparticles. The lightest CP-even scalar may have a mass in the 95-98~GeV range with, however, modest signal rates in view of the mild excesses reported in this range at LEP and by CMS at the LHC.

    hep-phhep-exEPJC(2022)·26 citations
13. 13*

    Random statistical analysis of transverse momentum spectra of strange particles and dependence of related parameters on centrality in high energy collisions at the LHC

    Xu-Hong Zhang🇨🇳 · Fu-Hu Liu🇨🇳 · Khusniddin K. Olimov🇺🇿 · Airton Deppman🇧🇷

    We have studied the transverse momentum ($p_T$) spectra of the final-state strange particles, including $K^{\pm }$, $\varphi$, $\Xi$, and $\Omega$, produced in high energy lead-lead (Pb-Pb), proton-lead ($p$-Pb), xenon-xenon (Xe-Xe) collisions at the Large Hadron Collider (LHC). Taking into account the contribution of multi-quark composition, whose probability density distribution is described by the modified Tsallis-Pareto-type function, we simulate the $p_T$ spectra of the final-state strange particles by a Monte Carlo method, which is shown to be in good agreement with the experimental data in most the cases. The kinetic freeze-out parameters are obtained. The present method provides a new tool for studying the spectra of various particles produced in high energy collisions, reflecting more realistically the collision process, which is of great significance to study the formation and properties of the produced particles.

    hep-phhep-exnucl-exnucl-thAdv.High Energy Phys.(2022)·2 citations
14. 14*

    Riemannian Data preprocessing in Machine Learning to focus on QCD color structure

    A. Hammad🇰🇷 · Myeonghun Park🇰🇷

    Identifying the quantum chromodynamics (QCD) color structure of processes provides additional information to enhance the reach for new physics searches at the Large Hadron Collider (LHC). Analyses of QCD color structure in the decay process of a boosted particle have been spotted as information becomes well localized in the limited phase space. While these kind of a boosted jet analyses provide an efficient way to identify a color structure, the constrained phase space reduces the number of available data, resulting in a low significance. In this letter, we provide a simple but a novel data preprocessing method using a Riemann sphere to utilize a full phase space by decorrelating QCD structure from a kinematics. We can achieve a statistical stability by enlarging the size of testable data set with focusing on QCD structure effectively. We demonstrate the power of our method at the finite statistics of the LHC Run 2. Our method is complementary to conventional boosted jet analyses in utilizing QCD information over the wide range of a phase space.

    hep-phhep-exJ.Korean Phys.Soc.(2023)·2 citations
15. 15*

    Plane-wave and wavepacket neutrino flavor oscillations in vacuum in conformal coupling models

    Fayçal Hammad🇨🇦 · Parvaneh Sadeghi🇨🇦 · Nicolas Fleury🇨🇦

    We investigate neutrino flavor oscillations in vacuum within a general conformal coupling model. We first examine the flavor oscillations within the plane-wave description of neutrinos, and then we extend our analysis to the wavepacket-based formalism. In both cases, we derive the general formulas for the flavor transition probability in arbitrary static and spherically symmetric spacetimes. We thoroughly discuss and assess in both cases the different possible ways -- dictated by the presence of the conformal coupling -- of computing the flavor transition probability. We show that the conformal invariance of the Dirac equation implies that the effect of conformal coupling on neutrino flavor oscillations modifies the oscillation length, but preserves the coherence length and unitarity. A detailed application to two-flavor neutrinos is then made and a numerical analysis is conducted within the well-known chameleon conformal coupling model.

    hep-phgr-qcPRD(2022)·6 citations
16. 16*

    N${}^3$LO+N${}^3$LL QCD improved Higgs pair cross sections

    A.H. Ajjath · Hua-Sheng Shao🇫🇷

    We report a new calculation of the soft-gluon threshold resummation for the Higgs boson pair production in the dominant production mode -- gluon-gluon fusion -- up to the next-to-next-to-next-to-leading logarithmic (N${}^3$LL) accuracy. After matching N${}^3$LL to the next-to-next-to-next-to-leading order (N${}^3$LO) QCD calculation in the infinite top quark mass approximation, we show that the central values of the inclusive cross sections are quite stable with respect to N${}^3$LO, while the conventional renormalisation and factorisation scale uncertainties are reduced by a factor of two, reaching to the subpercent level. Our study further consolidates the good asymptotic perturbative convergence. After combining with the full top-quark mass dependent next-to-leading order QCD results, our most advanced predictions are presented for both the inclusive total cross sections and the differential invariant mass distributions of the Higgs pair.

    hep-phhep-exJHEP(2023)·52 citations
17. 17*

    Axion-like particles as mediators for dark matter: beyond freeze-out

    A. Bharucha🇫🇷 · F. Brümmer🇫🇷 · N. Desai🇮🇳 · S. Mutzel🇫🇷

    We consider an axion-like particle (ALP) coupled to Standard Model (SM) fermions as a mediator between the SM and a fermionic dark matter (DM) particle. We explore the case where the ALP-SM and/or the ALP-DM couplings are too small to allow for DM generation via standard freeze-out. DM is therefore thermally decoupled from the visible sector and must be generated through either freeze-in or decoupled freeze-out (DFO). In the DFO regime, we present an improved approach to obtain the relic density by solving a set of three stiff coupled Boltzmann equations, one of which describes the energy transfer from the SM to the dark sector. Having determined the region of parameter space where the correct relic density is obtained, we revisit experimental constraints from electron beam dump experiments, rare $B$ and $K$ decays, exotic Higgs decays at the LHC, astrophysics, dark matter searches and cosmology. In particular, for our specific ALP scenario we (re)calculate and improve beam dump, flavour and supernova constraints. Throughout our calculation we implement state-of-the-art chiral perturbation theory results for the ALP partial decay width to hadrons. We find that while the DFO region, which predicts extremely small ALP-fermion couplings, can probably only be constrained by cosmological observables, the freeze-in region covers a wide area of parameter space that may be accessible to other more direct probes. Some of this parameter space is already excluded, but a significant part should be accessible to future collider experiments.

    hep-phJHEP(2023)·54 citations
18. 18*

    Standard Model Predictions for Rare K and B Decays without New Physics Infection

    Andrzej J. Buras🇩🇪

    The Standard Model (SM) does not contain by definition any new physics (NP) contributions to any observable but contains four CKM parameters which are not predicted by this model. We point out that if these four parameters are determined in a global fit that includes processes which are infected by NP, the resulting SM contributions to rare decay branching ratios cannot be considered as true SM contributions to the latter. On the other hand true SM predictions, that are free from the CKM dependence, can be obtained for suitable ratios of the $K$ and $B$ rare decay branching ratios to $\Delta M_s$, $\Delta M_d$ and $|{\epsilon }_K|$, all calculated within the SM. These three observables contain by now only small hadronic uncertainties and are already well measured so that rather precise true SM predictions for the ratios in question can be obtained. In this context the rapid test of NP infection in the $\Delta F=2$ sector is provided by a $|V_{cb}|-\gamma$ plot that involves $\Delta M_s$, $\Delta M_d$, $|{\epsilon }_K|$, and the mixing induced CP-asymmetry $S_{\psi K_S}$. As with the present hadronic matrix elements this test turns out to be negative, assuming negligible NP infection in the $\Delta F=2$ sector and setting the values of these four observables to the experimental ones, allows to obtain SM predictions for all $K$ and $B$ rare decay branching ratios that are most accurate to date and as a byproduct to obtain the full CKM matrix on the basis of $\Delta F=2$ transitions alone. Using this strategy we obtain SM predictions for 26 branching ratios for rare semileptonic and leptonic $K$ and $B$ decays with the ${\mu }^{+}{\mu }^{-}$ pair or the $\nu \bar{\nu }$ pair in the final state. Most interesting turn out to be the anomalies in the low $q^2$ bin in $B^{+}\to K^{+}{\mu }^{+}{\mu }^{-}$ ($4.4\sigma$) and $B_s\to \varphi {\mu }^{+}{\mu }^{-}$ ($4.8\sigma$).

    hep-phhep-exhep-latEPJC(2023)·67 citations
19. 19*

    The LPM effect in sequential bremsstrahlung: incorporation of "instantaneous'' interactions for QCD

    Peter Arnold🇺🇸 · Tyler Gorda🇩🇪 · Shahin Iqbal🇵🇰

    The splitting processes of bremsstrahlung and pair production in a medium are coherent over large distances in the very high energy limit, which leads to a suppression known as the Landau-Pomeranchuk-Migdal (LPM) effect. We continue study of the case when the coherence lengths (formation lengths) of two consecutive splitting processes overlap, avoiding soft-emission approximations. Previous work made a ``nearly-complete'' calculation of the effect of overlapping formation times on gluonic splittings such as $g\to gg\to ggg$ (with simplifying assumptions such as an infinite QCD medium and the large-$N_c$ limit). In this paper, we extend those previous rate calculations from nearly-complete to complete by including processes involving the exchange of longitudinally-polarized gluons. In the context of Lightcone Pertubation Theory, used earlier for the ``nearly-complete'' calculation, such exchanges are instantaneous in lightcone time and have their own diagrammatic representation.

    hep-phnucl-thJHEP(2022)·12 citations
20. 20*

    NuSmear: Fast Simulation of Energy Smearing and Angular Smearing for Neutrino-Nucleon Scattering Events in the GENIE Event Generator

    Ishaan Vohra🇺🇸

    Complete Monte Carlo (MC) simulation of a neutrino experiment typically involves the lengthy and CPU-intensive process of integrating models of incoming neutrino fluxes, event generation, and detector setup. We describe a fast, geometry-independent, GENIE-based system known as NuSmear which provides preliminary simulation of energy smearing and angular smearing for neutrino-nucleon interactions. We discuss NuSmear's simulation methodology, explaining its calculation of reconstructed values through its model-based resolution computation, smearing distributions, and particle detection dependencies. We go on to validate NuSmear's performance as a fast simulation system through a series of internal and external comparisons testing its predictive accuracy and model-adherence. Finally, we briefly explore the potential for future user-customization in NuSmear.

    hep-phhep-exphysics.ins-det1 citation
21. 21*

    Wideband Direct Detection Constraints on Hidden Photon Dark Matter with the QUALIPHIDE Experiment

    Karthik Ramanathan🇺🇸 · Nikita Klimovich🇺🇸 · Ritoban Basu Thakur🇺🇸 · Byeong Ho Eom🇺🇸 · Henry G. LeDuc🇺🇸 · Shibo Shu🇺🇸 · Andrew D. Beyer🇺🇸 · Peter K. Day🇺🇸

    We report direction detection constraints on the presence of hidden photon dark matter with masses between 20-30 ueV using a cryogenic emitter-receiver-amplifier spectroscopy setup designed as the first iteration of QUALIPHIDE (QUantum LImited PHotons In the Dark Experiment). A metallic dish sources conversion photons from hidden photon kinetic mixing onto a horn antenna which is coupled to a C-band kinetic inductance traveling wave parametric amplifier, providing for near quantum-limited noise performance. We demonstrate a first probing of the kinetic mixing parameter "chi" to just above 10^-12 for the majority of hidden photon masses in this region. These results not only represent stringent constraints on new dark matter parameter space but are also the first demonstrated use of wideband quantum-limited amplification for astroparticle applications

    ↳ astro-ph.COhep-exhep-phphysics.ins-detPRL(2023)·54 citations
22. 22*

    How Slowly can the Early Universe Expand?

    Robert J. Scherrer🇺🇸

    When the expansion of the universe is dominated by a perfect fluid with equation of state parameter $w$ and a sound speed $c_s$ satisfying $w=c_s^2\le 1$, the Hubble parameter $H$ and time $t$ satisfy the bound $Ht\ge 1/3$. There has been recent interest in "ultra-slow" expansion laws with $Ht<1/3$ (sometimes described as "fast expanding" models). We examine various models that can produce ultra-slow expansion: scalar fields with negative potentials, barotropic fluids, braneworld models, or a loitering phase in the early universe. Scalar field models and barotropic models for ultra-slow expansion are unstable to evolution toward $w=1$ or $w\to \infty$ in the former case and $w\to \infty$ in the latter case. Braneworld models can yield ultra-slow expansion but require an expansion law beyond the standard Friedman equation. Loitering early universe models can produce a quasi-static expansion phase in the early universe but require an exotic negative-density component. These results suggest that appeals to an ultra-slow expansion phase in the early universe should be approached with some caution, although the loitering early universe may be worthy of further investigation. These results do not apply to ultra-slow contracting models.

    ↳ astro-ph.COgr-qchep-phPRD(2022)·7 citations
23. 23*

    Cold dense quark matter with phenomenological medium effects: a self-consistent formulation of the quark-mass density-dependent model

    G. Lugones🇧🇷 · A. G. Grunfeld🇦🇷

    We revisit the quark-mass density-dependent model -- a phenomenological equation of state for deconfined quark matter in the high-density low-temperature regime -- and show that thermodynamic inconsistencies that have plagued the model for decades, can be solved if the model is formulated in the canonical ensemble instead of the grand canonical one. Within the new formulation, the minimum of the energy per baryon occurs at zero pressure, and the Euler's relation is verified. Adopting a typical mass-formula, we first analyze in detail a simple model with one particle species. We show that a ``bag'' term that produces quark confinement naturally appears in the pressure (and not in the energy density) due to density dependence of the quark masses. Additionally, the chemical potential gains a new term as in other models with quark repulsive interactions. Then, we extend the formalism to the astrophysically realistic case of charge-neutral three-flavor quark matter in equilibrium under weak interactions, focusing on two different mass formulae: a flavor dependent and a flavor blind one. For these two models, we derive the equation of state and analyze its behavior for several parameter choices. We systematically analyze the parameter space and identify the regions corresponding to self-bound 2-flavor and 3-flavor quark matter, hybrid matter and causal behavior.

    ↳ nucl-thastro-ph.SRhep-phPRD(2023)·20 citations
24. 24*

    Search for the Chiral Magnetic Effect in Au+Au collisions at $\sqrt{s_{{}_{\mathrm{NN}}}}=27$ GeV with the STAR forward Event Plane Detectors

    STAR Collaboration: B. E. Aboona🇺🇸 · J. Adam🇨🇿 · L. Adamczyk🇵🇱 · J. R. Adams🇺🇸 · I. Aggarwal🇮🇳 · M. M. Aggarwal🇮🇳 · Z. Ahammed🇮🇳 · D. M. Anderson🇺🇸 · E. C. Aschenauer🇺🇸 · J. Atchison🇺🇸 · V. Bairathi🇨🇱 · W. Baker🇺🇸 and 359 other authors

    A decisive experimental test of the Chiral Magnetic Effect (CME) is considered one of the major scientific goals at the Relativistic Heavy-Ion Collider (RHIC) towards understanding the nontrivial topological fluctuations of the Quantum Chromodynamics vacuum. In heavy-ion collisions, the CME is expected to result in a charge separation phenomenon across the reaction plane, whose strength could be strongly energy dependent. The previous CME searches have been focused on top RHIC energy collisions. In this Letter, we present a low energy search for the CME in Au+Au collisions at $\sqrt{s_{{}_{\mathrm{NN}}}}=27$ GeV. We measure elliptic flow scaled charge-dependent correlators relative to the event planes that are defined at both mid-rapidity $|\eta |<1.0$ and at forward rapidity $2.1<|\eta |<5.1$. We compare the results based on the directed flow plane (${\Psi }_1$) at forward rapidity and the elliptic flow plane (${\Psi }_2$) at both central and forward rapidity. The CME scenario is expected to result in a larger correlation relative to ${\Psi }_1$ than to ${\Psi }_2$, while a flow driven background scenario would lead to a consistent result for both event planes. In 10-50\% centrality, results using three different event planes are found to be consistent within experimental uncertainties, suggesting a flow driven background scenario dominating the measurement. We obtain an upper limit on the deviation from a flow driven background scenario at the 95\% confidence level. This work opens up a possible road map towards future CME search with the high statistics data from the RHIC Beam Energy Scan Phase-II.

    ↳ nucl-exhep-phnucl-thPLB(2023)·29 citations
25. 25*

    Light Curves and Event Rates of Axion Instability Supernovae

    Kanji Mori🇯🇵 · Takashi J. Moriya🇯🇵 · Tomoya Takiwaki🇯🇵 · Kei Kotake🇯🇵 · Shunsaku Horiuchi🇺🇸 · Sergei I. Blinnikov🇷🇺

    It was recently proposed that exotic particles can trigger a new stellar instability which is analogous to the e-e+ pair instability if they are produced and reach equilibrium in the stellar plasma. In this study, we construct axion instability supernova (AISN) models caused by the new instability to predict their observational signatures. We focus on heavy axion-like particles (ALPs) with masses of ~400 keV--2 MeV and coupling with photons of g_{ag}~10^{-5} GeV^{-1}. It is found that the 56Ni mass and the explosion energy are significantly increased by ALPs for a fixed stellar mass. As a result, the peak times of the light curves of AISNe occur earlier than those of standard pair-instability supernovae by 10--20 days when the ALP mass is equal to the electron mass. Also, the event rate of AISNe is 1.7--2.6 times higher than that of pair-instability supernovae, depending on the high mass cutoff of the initial mass function.

    ↳ astro-ph.HEastro-ph.SRhep-phnucl-thApJ(2023)·7 citations
26. 26*

    Extracting ultralight boson properties from boson clouds around post-merger remnants

    Kelvin H. M. Chan · Otto A. Hannuksela🇨🇳

    Ultralight bosons are a class of hypothetical particles that could potentially solve critical problems in fields ranging from cosmology to astrophysics and fundamental physics. If ultralight bosons exist, they form clouds around spinning black holes with sizes comparable to their particle Compton wavelength through superradiance, a well-understood classical wave amplification process that has been studied for decades. After these clouds form, they dissipate and emit continuous gravitational waves through the annihilation of ultralight bosons into gravitons. These gravitons could be detected with ground-based gravitational-wave detectors using continuous-wave searches. However, it is conceivable for other continuous-wave sources to mimic the emission from the clouds, which could lead to false detections. Here we investigate how one can use continuous waves from clouds formed around known merger remnants to alleviate this problem. In particular, we simulate a catalogue of merger remnants that form clouds around them and demonstrate with select "golden" merger remnants how one can perform a Bayesian cross-verification of the ultralight boson hypothesis that has the potential to rule out alternative explanations. Our proof-of-concept study suggest that, in the future, there is a possibility that a merger remnant exists close enough for us to perform the analysis and test the boson hypothesis if the bosons exist in the relevant mass range. Future research will focus on building more sophisticated continuous-wave tools to perform this analysis in practice.

    ↳ gr-qcastro-ph.HEhep-phPRD(2024)·16 citations
27. 27*

    Spin polarization measurements in relativistic heavy-ion collisions

    Debojit Sarkar🇺🇸

    The hot and dense matter formed in relativistic heavy-ion collisions at Relativistic Heavy Ion Collider (RHIC) and Large Hadron Collider (LHC) is termed quark-gluon plasma (QGP). The evolution of the medium is characterized by non-trivial velocity and vorticity fields, resulting in the polarization of the produced particles. The spin polarization, being sensitive to the hydrothermal (flow velocity and temperature) gradients, is unique compared to conventional observables that are sensitive to the hydrothermal fields only. Hence, the recent measurements of global and local hyperon spin polarization and vector meson spin alignment by the LHC and STAR collaborations provide a unique opportunity to probe the QGP substructure with finer details.

    ↳ hep-exhep-phnucl-exnucl-th+1Acta Phys.Polon.Supp.(2023)·0 citations
28. 28*

    Can the Production Cross-Section Uncertainties Explain the Cosmic Fluorine Anomaly?

    Meng-Jie Zhao🇨🇳 · Xiao-Jun Bi🇨🇳 · Kun Fang🇨🇳

    The stable secondary-to-primary flux ratios of cosmic rays (CRs), represented by the boron-to-carbon ratio (B/C), are the main probes of the Galactic CR propagation. However, the fluorine-to-silicon ratio (F/Si) predicted by the CR diffusion coefficient inferred from B/C is significantly higher than the latest measurement of AMS-02. This anomaly is commonly attributed to the uncertainties of the F production cross sections. In this work, we give a careful test to this interpretation. We consider four different cross-section parametric models. Each model is constrained by the latest cross-section data. We perform combined fits to the B/C, F/Si, and cross-section data with the same propagation framework. Two of the cross-section models have good overall goodness of fit with ${\chi }^2/n_{d.o.f.}\sim 1$. However, the goodness of fit of the cross-section part is poor with ${\chi }_{\mathrm{cs}}^2/n_{\mathrm{cs}}\gtrsim 2$ for these models. The best-fitted F production cross sections are systematically larger than the measurements, while the fitted cross sections for B production are systematically lower than the measurements. This indicates that the F anomaly can hardly be interpreted by neither the random errors of the cross-section measurements nor the differences between the existing cross-section models. We then propose that the spatially dependent diffusion model could help to explain B/C and F/Si consistently. In this model, the average diffusion coefficient of the Ne-Si group is expected to be larger than that of the C-O group.

    ↳ astro-ph.HEhep-phPRD(2023)·9 citations
29. 29*

    A Symbol and Coaction for Higher-Loop Sunrise Integrals

    Andreas Forum🇩🇰 · Matt von Hippel🇩🇰

    We construct a symbol and coaction for $l$-loop sunrise integrals, both for the equal-mass and generic-mass cases. These constitute the first concrete examples of symbols and coactions for integrals involving Calabi-Yau threefolds and higher. In order to achieve a symbol of finite length, we recast the differential equations satisfied by the master integrals of this topology in the form of a unipotent differential equation. We augment the basis of master integrals in a natural way by including ratios of maximal cuts ${\tau }_i$. We discuss the relationship of this construction to constructions of symbols and coactions for multiple polylogarithms and elliptic multiple polylogarithms, in particular its connection to notions of transcendental weight.

    ↳ hep-thhep-phSciPost Phys.Core(2023)·25 citations
30. 30*

    Astrophysical Observations of a Dark Matter-Baryon Fifth Force

    Moira I. Gresham🇺🇸 · Vincent S. H. Lee🇺🇸 · Kathryn M. Zurek🇺🇸

    We consider the effects of an attractive, long-range Yukawa interaction between baryons and dark matter (DM), focusing in particular on temperature and pulsar timing observations of neutron stars (NSs). We show that such a fifth force, with strength modestly stronger than gravity at ranges greater than tens of kilometers (corresponding to mediator masses less than $10^{-11}\text{eV}$), can dramatically enhance dark matter kinetic heating, capture, and pulsar timing Doppler shifts relative to gravity plus short range interactions alone. Using the coldest observed NS and pulsar timing array (PTA) data, we derive limits on fifth force strength over a DM mass range spanning light dark matter up to order solar mass composite DM objects. We also consider an indirect limit by combining bullet cluster limits on the DM self-interaction with weak equivalence principle test limits on baryonic self-interactions. We find the combined indirect limits are moderately stronger than kinetic heating and PTA limits, except when considering a DM subcomponent.

    ↳ astro-ph.HEhep-phJCAP(2023)·23 citations
31. 31*

    Quantum discord and steering in top quarks at the LHC

    Yoav Afik🇨🇭 · Juan Ramón Muñoz de Nova🇪🇸

    Top quarks have been recently shown to be a promising system to study quantum information at the highest-energy scale available. The current lines of research mostly discuss topics such as entanglement, Bell nonlocality or quantum tomography. Here, we provide the full picture of quantum correlations in top quarks by studying also quantum discord and steering. We find that both phenomena are present at the LHC. In particular, quantum discord in a separable quantum state is expected to be detected with high-statistical significance. Interestingly, due to the singular nature of the measurement process, quantum discord can be measured following its original definition, and the steering ellipsoid can be experimentally reconstructed, both highly-demanding measurements in conventional setups. In contrast to entanglement, the asymmetric nature of quantum discord and steering can provide witnesses of $CP$-violating physics beyond the Standard Model.

    ↳ quant-phhep-exhep-phhep-thPRL(2023)·148 citations
32. 32*

    Where are Milky Way's Hadronic PeVatrons?

    Takahiro Sudoh🇺🇸 · John F. Beacom🇺🇸

    Observations of the Milky Way at TeV-PeV energies reveal a bright diffuse flux of hadronic cosmic rays and also bright point sources of gamma rays. If the gamma-ray sources are hadronic cosmic-ray accelerators, then they must also be neutrino sources. However, no neutrino sources have been detected. Where are they? We introduce a new population-based approach to probe Milky Way hadronic PeVatrons, demanding consistency between diffuse and point-source PeV-range data on cosmic rays, gamma rays, and neutrinos. For the PeVatrons, two extreme scenarios are allowed: (1) the hadronic cosmic-ray accelerators and the gamma-ray sources are the same objects, so that bright neutrino sources exist and improved telescopes can detect them, versus (2) the hadronic cosmic-ray accelerators and the gamma-ray sources are distinct, so that there are no detectable neutrino sources. The latter case is possible if hadronic accelerators have sufficiently thin column densities. We quantify present constraints and future prospects, showing how to reveal the nature of the hadronic PeVatrons.

    ↳ astro-ph.HEastro-ph.GAhep-phPRD(2023)·32 citations
33. 33*

    Full-shape BOSS constraints on dark matter interacting with dark radiation and lifting the $S_8$ tension

    Henrique Rubira🇩🇪 · Asmaa Mazoun🇩🇪 · Mathias Garny🇩🇪

    In this work we derive constraints on interacting dark matter-dark radiation models from a full-shape analysis of BOSS-DR12 galaxy clustering data, combined with Planck legacy cosmic microwave background (CMB) and baryon acoustic oscillation (BAO) measurements. We consider a set of models parameterized within the effective theory of structure formation (ETHOS), quantifying the lifting of the $S_8$ tension in view of KiDS weak-lensing results. The most favorable scenarios point to a fraction $f\sim 10-100\%$ of interacting dark matter as well as a dark radiation temperature that is smaller by a factor $\xi \sim 0.1-0.15$ compared to the CMB, leading to a reduction of the tension to the $\sim 1\sigma$ level. The temperature dependence of the interaction rate favored by relaxing the $S_8$ tension is realized for a weakly coupled unbroken non-Abelian $SU(N)$ gauge interaction in the dark sector. To map our results onto this $SU(N)$ model, we compute higher-order corrections due to Debye screening. We find a lower bound ${\alpha }_d\equiv g_d^2/(4\pi )\gtrsim 10^{-8}(10^{-9})$ for dark matter mass $1000(1)$ GeV for relaxing the $S_8$ tension, consistent with upper bounds from galaxy ellipticities and compatible with self-interactions relevant for small-scale structure formation.

    ↳ astro-ph.COhep-phJCAP(2023)·42 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.