Wed·Sep 14, 2022Wednesday·September 14, 2022

1. 01*

   VBF vs. GGF Higgs with Full-Event Deep Learning: Towards a Decay-Agnostic Tagger

   Cheng-Wei Chiang🇹🇼 · David Shih🇺🇸 · Shang-Fu Wei🇹🇼

   We study the benefits of jet- and event-level deep learning methods in distinguishing vector boson fusion (VBF) from gluon-gluon fusion (GGF) Higgs production at the LHC. We show that a variety of classifiers (CNNs, attention-based networks) trained on the complete low-level inputs of the full event achieve significant performance gains over shallow machine learning methods (BDTs) trained on jet kinematics and jet shapes, and we elucidate the reasons for these performance gains. Finally, we take initial steps towards the possibility of a VBF vs. GGF tagger that is agnostic to the Higgs decay mode, by demonstrating that the performance of our event-level CNN does not change when the Higgs decay products are removed. These results highlight the potentially powerful benefits of event-level deep learning at the LHC.

   hep-phhep-exPRD(2023)·7 citations
2. 02*

   One-Loop Integrals for Purely Virtual Particles

   Aurora Melis🇪🇪 · Marco Piva🇪🇪

   Quantum field theories with purely virtual particles, or fakeons, require suitable modifications in one-loop integrals. We provide the expressions for the modified scalar integrals in the case of the bubble, triangle and box diagrams. The new functions are defined by means of their difference with the `t Hooft-Veltman scalar integrals. The modifications do not affect the derivation of the Passarino-Veltman reduction and one-loop integrals with nontrivial numerators can be decomposed in the same fashion. Therefore, the new functions can be directly used to study the phenomenology of any models with standard particles and fakeons. We compare our results with standard amplitudes and show that the largest differences are often localized in relatively small energy ranges and are characterized by additional nonanalyticities. Finally, we give explicit examples in the context of a toy model, where cross sections and decay widths of standard particles are modified by the presence of fakeons.

   hep-phhep-thPRD(2023)·8 citations
3. 03*

   Hadronization effects on transverse momentum dependent jet fragmentation function in small systems

   Xiang-Pan Duan🇨🇳 · Wenbin Zhao🇺🇸 · Guo-Liang Ma🇨🇳

   The transverse momentum $j_{\mathrm{T}}$-dependent jet fragmentation functions have been investigated in proton+proton (p $+$ p) and proton+lead (p $+$ Pb) collisions at $\sqrt{s_{\mathrm{NN}}}=5.02\mathrm{TeV}$ with a multiphase transport model containing both a simple quark coalescence mechanism and a new hybrid hadronization mechanism with coalescence and fragmentation processes. Hadronized by the new hadronization mechanism, the AMPT model achieves a quantitative description of the $j_{\mathrm{T}}$-dependent jet fragmentation functions measured by ALICE. Besides, no obvious jet-medium interaction and cold nuclear matter effects on the $j_{\mathrm{T}}$-dependent jet fragmentation functions in p $+$ Pb collisions were observed. We found the $j_{\mathrm{T}}$-dependent jet fragmentation functions are dominated by the quark coalescence contribution for the new hadronization mechanism, which can be decomposed into narrow and wide parts. The root mean square value of the wide part depends on the jet radius $R$ and jet transverse momentum $p_{\mathrm{T},\mathrm{jet}}$, which is sensitive to different hadronization mechanisms and their components. Therefore, the $j_{\mathrm{T}}$-dependent jet fragmentation functions are proposed as a sensitive probe to study the non-perturbative hadronization effect of jets in small colliding systems.

   hep-phnucl-exnucl-thEur.Phys.J.Plus(2023)·4 citations
4. 04*

   Estimation of coupling constants for D-meson, charmed, and light baryons in effective Lagrangian approach and quark model

   Thanat Sangkhakrit🇹🇭 · Attaphon Kaewsnod🇹🇭 · Warintorn Sreethawong🇹🇭 · Thananuwat Suyuporn🇹🇭 · Nopmanee Supanam🇹🇭 · Daris Samart🇹🇭 · Yupeng Yan🇹🇭

   We estimate coupling constants for effective Lagrangians of $D$-meson, charmed, and light baryons from charmed baryon decay processes. First, we calculate decay widths for the processes ${\Lambda }_c\to DN$, ${\Sigma }_c\to D\Delta$, ${\Sigma }_c\to D^{\ast }\Delta$, and ${\Lambda }_c\to D^{\ast }N$ in effective Lagrangian method and quark model picture with ${}^3{P}_0$ model. By employing the coupling constants for $D^{\ast }{\Lambda }_{c}N$ interaction from several literatures, the strength parameter $\lambda$ for ${}^3{P}_0$ quark model is fixed in the decay process ${\Lambda }_c\to D^{\ast }N$. Then, the coupling constants for the effective Lagrangians of $D{\Lambda }_{c}N$, $D{\Sigma }_c\Delta$, and $D^{\ast }{\Sigma }_c\Delta$ interactions are estimated in the decay channels ${\Lambda }_c\to DN$, ${\Sigma }_c\to D\Delta$, and ${\Sigma }_c\to D^{\ast }\Delta$, respectively. These coupling constants will be useful for further studies of charm hadrons.

   hep-phEPJA(2023)·0 citations
5. 05*

   Production of single-charmed baryons in a quark model approach

   Daniel Iglesias-Ferrero🇪🇸 · David R. Entem🇪🇸 · Francisco Fernández🇪🇸 · Pablo G. Ortega🇪🇸

   The production of single-charmed baryons ${\Lambda }_c^{+}{\Lambda }_c^{-}$, ${\Lambda }_c^{+}{\Sigma }_c^{-}$+h.c. and ${\Sigma }_c^{+}{\Sigma }_c^{-}$ in $p\bar{p}$ collisions is studied in the framework of a constituent quark model which has satisfactorily described the $N\bar{N}$ system and the strangeness production $p\bar{p}\to \Lambda \bar{\Lambda }$, $\Lambda \bar{\Sigma }$ and $\Sigma \bar{\Sigma }$ processes. Predictions on the total cross sections are analyzed for different approaches to the underlying $n\bar{n}\to c\bar{c}$ process, mediated by one gluon annihilation diagrams. The results indicate that the cross section is of the order of $1$ nb between $10-14$ GeV for ${\Lambda }_c^{+}{\Lambda }_c^{-}$ and ${\Lambda }_c^{+}{\Sigma }_c^{-}$ channels, and around $0.01-0.1$ nb for ${\Sigma }_c^{+}{\Sigma }_c^{-}$. This estimations can be relevant for their future search in facilities like $\bar{P}$ANDA.

   hep-phhep-exPRD(2022)·2 citations
6. 06*

   Computing one-loop radiative corrections in $\tau \to \pi (K)\nu [\gamma ]$ and testing new physics

   Ignasi Rosell🇪🇸

   Without a doubt the ratios $R_{\tau /P}\equiv \Gamma \left(\tau \to P{\nu }_{\tau }[\gamma ]\right)/\Gamma \left(P\to \mu {\nu }_{\mu }[\gamma ]\right)$ ($P=\pi ,K$) give a convenient scenario to test the lepton universality, the CKM unitarity and to search for non-standard interactions in $\tau$ decays. Moreover, the previous theoretical estimation of these observables is more than twenty-five years old and some assumptions of that estimation are unrealistic. Therefore, an update of $R_{\tau /P}$ was timely. The one-loop radiative corrections have been computed by considering an expansion of Chiral Perturbation Theory including the lightest spin-one resonances and respecting the short-distance behavior dictated by QCD. We have reported $\delta R_{\tau /\pi }=(0.18\pm 0.57)\%$ and $\delta R_{\tau /K}=(0.97\pm 0.58)\%$, where the uncertainties have been induced fundamentally by the estimation of the counterterms. We have tested the lepton universality, the CKM unitarity and have searched for new physics in $\tau$ decays. As a by-product, we have also determined the theoretical radiative corrections to the $\tau \to P{\nu }_{\tau }[\gamma ]$ decay rates, ${\delta }_{\tau \pi }=-(0.24\pm 0.56)\%$ and ${\delta }_{\tau K}=-(0.15\pm 0.57)\%$

   hep-phEPJ Web Conf.(2022)·0 citations
7. 07*

   XYZ spectroscopy at electron-hadron facilities II: Semi-inclusive processes with pion exchange

   JPAC Collaboration: D. Winney🇨🇳 · A. Pilloni🇮🇹 · V. Mathieu🇪🇸 · A. N. Hiller Blin🇩🇪 · M. Albaladejo🇪🇸 · W. A. Smith🇺🇸 · A. Szczepaniak🇺🇸

   Semi-inclusive processes are very promising to investigate $XYZ$ hadrons at the next generation of electron-hadron facilities, because they generally boast higher cross sections. We extend our formalism of exclusive photoproduction to semi-inclusive final states. The inclusive production cross sections for charged axial-vector $Z$ states from pion exchange are predicted. We isolate the contribution of $\Delta$ resonances at small missing mass. Production near threshold is shown to be enhanced roughly by a factor of two compared to the exclusive reaction. We benchmark the model with data of semi-inclusive $b_1^{\pm }$ production.

   hep-phhep-exPRD(2022)·23 citations
8. 08*

   Phenomenology of Scalar Leptoquarks at the LHC in Explaining the Radiative Neutrino Mass, Muon $g-2$ and Lepton Flavour Violating Observables

   Snehashis Parashar🇮🇳 · Anirban Karan🇪🇸 · Avnish🇮🇳 · Priyotosh Bandyopadhyay🇮🇳 · Kirtiman Ghosh🇮🇳

   We study the phenomenology of a particular leptoquark extension of the Standard Model (SM), namely the doublet-singlet scalar leptoquark extension of the SM (DSL-SM). Besides generating Majorana mass for neutrinos, these leptoquarks contribute to muon and electron $(g-2)$ and various lepton flavour violating processes. Collider signatures of the benchmark points (BPs), consistent with the neutrino oscillation data, anomalous muon/electron magnetic moments, experimental bounds on the charged lepton flavour violation observables, etc., are studied at the LHC/FCC with centre-of-mass energies of 14, 27 and 100 TeV. While the two $-1/3$ charged colored scalars from singlet and doublet leptoquark mix with each other, the charge $2/3$ colored scalar from the doublet leptoquark remains pure. With a near-degenerate mass spectrum, the pure and mixed leptoquark states are shown to be distinguishable from multiple finalstates, while discerning between the two mixed states remain very challenging.

   hep-phPRD(2022)·26 citations
9. 09*

   Spin correlations in $\tau$-lepton pair production due to anomalous magnetic and electric dipole moments

   Sw. Banerjee🇺🇸 · A.Yu. Korchin🇺🇦 · Z. Was🇵🇱

   We present a simple algorithm for the calculation of event weights embedding the effects of anomalous electric and magnetic dipole moments in simulation of $e^{-}{e}^{+}\to {\tau }^{-}{\tau }^{+}(n\gamma )$ events, and the subsequent decay of the $\tau$ leptons produced. The impact of these weights on the spin-correlation matrix and the total cross section is taken into account. The algorithm is prepared to work in situ the Monte Carlo KKMC program without the need for introducing any external change to the generator libraries. As an example, $e^{-}{e}^{+}\to {\tau }^{-}{\tau }^{+}(n\gamma ),{\tau }^{-}\to {\rho }^{-}{\nu }_{\tau }\to {\pi }^{-}{\pi }^0{\nu }_{\tau },{\tau }^{+}\to {\rho }^{+}{\bar{\nu }}_{\tau }\to {\pi }^{+}{\pi }^0{\bar{\nu }}_{\tau }$ events were simulated at a center-of-mass energy of 10.58 GeV. The distributions of the acoplanarity angle between the planes spanned by the ${\pi }^{-}{\pi }^0$ and the ${\pi }^{+}{\pi }^0$ momenta of, respectively, ${\rho }^{-}$ and ${\rho }^{+}$ decays and in the rest frame of the entirely visible ${\rho }^{-}{\rho }^{+}$ system are presented for different values of the coupling constants incorporating anomalous electric and magnetic dipole moments in the ${\tau }^{-}{\tau }^{+}\gamma$ vertex.

   hep-phPRD(2022)·16 citations
10. 10*

    Searching for $X_0(2900)$ and $X_1(2900)$ through the kaon induced reactions

    Qing-Yong Lin🇨🇳 · Xiao-Yun Wang🇨🇳

    The productions of the exotic states $X_0(2900)$ and $X_1(2900)$ in $K^{+}p\to {\Sigma }_c^{++}{X}_0(2900)$ and $K^{+}p\to {\Sigma }_c^{++}{X}_1(2900)$ reactions are studied within an effective Lagrangian approach. The $t-$channel Born term is included to calculate the production cross sections. The numerical results show that the total cross section may reach up to about 0.5 nb and 25 nb for the production of $X_0(2900)$ and $X_1(2900)$, respectively. The predicted differential cross sections are sensitive to the scattering angles and have strong forward enhancements. The cross sections for the $K^{+}n\to {\Lambda }_c^{+}{X}_{0,1}$ are also calculated and found to be larger than that in $K^{+}p$ collisions by more than one order of magnitude. The results are helpful to the possible experiments at J-PARC and COMPASS.

    hep-phhep-exEPJC(2022)·14 citations
11. 11*

    Strongly-ordered infrared limits for subtraction counterterms from factorisation

    Lorenzo Magnea🇮🇹 · Calum Milloy🇮🇹 · Chiara Signorile-Signorile🇩🇪 · Paolo Torrielli🇮🇹 · Sandro Uccirati🇮🇹

    After a brief introduction to the problem of subtraction of infrared divergences for high-order collider observables, we present a preliminary study of strongly-ordered soft and collinear multiple radiation from the point of view of factorisation. We show that the matrix elements of fields and Wilson lines that describe soft and collinear radiation in factorised scattering amplitudes can be re-factorised in strongly-ordered limits, providing a systematic method to compute them, to characterise their singularity structure, and to build local subtraction counterterms for strongly-ordered configurations. Our results provide tools for a detailed organisation of subtraction algorithms, in principle to all orders in perturbation theory.

    hep-phPoS(2022)·4 citations
12. 12*

    Inclusive Production Cross Sections at N3LO

    Julien Baglio🇨🇭 · Claude Duhr🇩🇪 · Bernhard Mistlberger🇺🇸 · Robert Szafron🇺🇸

    We present for the first time the inclusive cross section for associated Higgs boson production with a massive gauge boson at next-to-next-to-next-to-leading order in QCD. Furthermore, we introduce n3loxs, a public, numerical program for the evaluation of inclusive cross sections at the third order in the strong coupling constant. Our tool allows to derive predictions for charged- and neutral-current Drell-Yan production, gluon- and bottom-quark-fusion Higgs boson production and Higgs boson associated production with a heavy gauge boson. We discuss perturbative and parton distribution function (PDF) uncertainties of the aforementioned processes. We perform a comparison of global PDF sets for a variety of process including associated Higgs boson production and observe $1\sigma$ deviations among predictions for several processes.

    hep-phJHEP(2022)·120 citations
13. 13*

    Investigating the role of partonic and hadronic dynamics in mass splitting of elliptic anisotropy in p-Pb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV

    Debojit Sarkar🇮🇳 · Subikash Choudhury🇮🇳 · Subhasis Chattopadhyay🇮🇳

    The mass ordering of $v_2^{hadron}$ is regarded as one of the key signatures of collective behaviour in ultra relativistic heavy ion collisions. This observation has been found to be in compliance with the hydrodynamical response of a strongly interacting system to the initial spatial anisotropy. Flow co-efficients measured with identified particles in p-Pb/d-Au collisions have shown similar mass-splitting of $v_2^{hadron}$ indicating towards the presence of collective dynamics in small collision systems. Arguably, small size in the overlap geometry of such colliding systems may not be suitable for hydrodynamical treatment that demands an early thermalization. Studies based on a multi phase transport model suggests that elliptic or triangular anisotropy is primarily due to escape mechanism of partons rather than hydro like collectivity and mass ordering of $v_2^{hadron}$ can be generated from coalescence dynamics as implemented in string melting version of AMPT even when parton azimuthal directions are randomized. In this work, studies have been performed on p-Pb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV using AMPT model which has been found to explain the elliptic and traingular flow in such a system where escape mechanism is the dominant source of flow generation. We report that the mass splitting of $v_2^{hadron}$ can originate independently both at the partonic and hadronic level in the string melting version of the AMPT model.

    hep-phhep-exnucl-thPRC(2016)·7 citations
14. 14*

    Phenomenological implications of the new Littlest Higgs model with T-parity

    José Ignacio Illana🇪🇸 · José María Pérez-Poyatos🇪🇸

    We investigate the parameter space of the new Littlest Higgs model with T-parity (NLHT) recently introduced to cure some pathologies of the original LHT. The model requires extra fermion content and additional pseudo-Goldstone bosons. While the heavy top quark sector is similar, there are both T-odd and T-even heavy quarks and leptons with masses proportional to just two sets of Yukawa matrices in flavor space, one more than in the LHT. The new scalars are a singlet and real triplet, T-odd, with masses controlled by gauge and Yukawa couplings, independent of the spontaneous symmetry breaking scale $f$, and hence potentially light. Imposing that no mass exceeds the cutoff scale, applying current lower bounds on vector-like quarks and assuming a simplified model with mass degenerate heavy fermions compatible with the heavy photon as dark matter constituent, we find that $f$ gets constrained within the interval between 2 and 3 TeV, the common Yukawa coupling of heavy leptons gets fixed and the Yukawa coupling of heavy quarks becomes greatly correlated to the top quark Yukawa couplings. The particle spectrum is then bounded from below and above, with the (lightest) heavy photon at about 0.5 TeV, not far from the heavy leptons, the new scalars below 1 TeV, the usual complex scalar triplet close to the heavy weak bosons at about 1.5 to 2.5 TeV, and the heavy quarks and top quark partners between 2 and 5 TeV. The new scalars decay predominantly to a standard and a T-odd lepton and have a width comparable to that of the Higgs.

    hep-phJHEP(2022)·3 citations
15. 15*

    Ridge from jet-medium interaction in p-Pb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV

    Debojit Sarkar🇮🇳 · Subhasis Chattopadhyay🇮🇳

    In this paper we report the effect of the jet-medium interplay as implemented in EPOS 3 on the ridge like structure observed in high multiplicity p-Pb collisions at $\sqrt{s_{NN}}=$ 5.02 TeV. EPOS 3 takes into account hydrodynamically expanding bulk matter, jets and the jet-medium interaction. The basis of this model is multiple scatterings where each scattering finally produces flux tube / string. In the higher multiplicity event classes where the flux tube/string density is higher, there is a finite probability that the strings will pick up quarks and antiquarks (or diquarks) from the bulk (core) for flux tube breaking to produce jet hadrons (corona) instead of producing them via usual Schwinger mechanism. This will eventually create a correlation between core and corona and also influence the corona-corona correlation as the corona particles containing quarks and antiquarks (or diquarks) from the bulk also carry the fluid information. We report the relative contributions of the core-core, core-corona, corona-core and corona-corona correlations towards the ridge in the high and low multiplicity p-Pb collisions at $\sqrt{s_{NN}}=$ 5.02 TeV using the data generated by EPOS 3. The multiplicity evolution of the ridges in all the cases is also reported.

    hep-phhep-exnucl-thPRC(2017)·5 citations
16. 16*

    The Irreducible Axion Background

    Kevin Langhoff🇺🇸 · Nadav Joseph Outmezguine🇺🇸 · Nicholas L. Rodd🇨🇭

    Searches for dark matter decaying into photons constrain its lifetime to be many orders of magnitude larger than the age of the Universe. A corollary statement is that the abundance of any particle that can decay into photons over cosmological timescales is constrained to be much smaller than the cold dark-matter density. We show that an $\text{irreducible}$ freeze-in contribution to the relic density of axions is in violation of that statement in a large portion of the parameter space. This allows us to set stringent constraints on axions in the mass range $100\mathrm{eV}-100\mathrm{MeV}$. At $10\mathrm{keV}$ our constraint on a photophilic axion is $g_{a\gamma \gamma }\lesssim 8.1\times 10^{-14}{\mathrm{GeV}}^{-1}$, almost three orders of magnitude stronger than the bounds established using horizontal branch stars; at $100\mathrm{keV}$ our constraint on a photophobic axion coupled to electrons is $g_{aee}\lesssim 8.0\times 10^{-15}$, almost four orders of magnitude stronger than present results. Although we focus on axions, our argument is more general and can be extended to, for instance, sterile neutrinos.

    hep-phastro-ph.COastro-ph.HEPRL(2022)·121 citations
17. 17*

    Anomaly Detection under Coordinate Transformations

    Gregor Kasieczka🇩🇪 · Radha Mastandrea🇺🇸 · Vinicius Mikuni🇺🇸 · Benjamin Nachman🇺🇸 · Mariel Pettee🇺🇸 · David Shih🇺🇸

    There is a growing need for machine learning-based anomaly detection strategies to broaden the search for Beyond-the-Standard-Model (BSM) physics at the Large Hadron Collider (LHC) and elsewhere. The first step of any anomaly detection approach is to specify observables and then use them to decide on a set of anomalous events. One common choice is to select events that have low probability density. It is a well-known fact that probability densities are not invariant under coordinate transformations, so the sensitivity can depend on the initial choice of coordinates. The broader machine learning community has recently connected coordinate sensitivity with anomaly detection and our goal is to bring awareness of this issue to the growing high energy physics literature on anomaly detection. In addition to analytical explanations, we provide numerical examples from simple random variables and from the LHC Olympics Dataset that show how using probability density as an anomaly score can lead to events being classified as anomalous or not depending on the coordinate frame.

    hep-phhep-exphysics.data-anPRD(2023)·32 citations
18. 18*

    Effect of radial flow on two particle correlations with identified triggers at intermediate $p_T$ in p-Pb collisions at $\sqrt{s_{NN}}=$ 5.02 TeV

    Debojit Sarkar🇮🇳 · Subikash Choudhury🇮🇳 · Subhasis Chattopadhyay🇮🇳

    Results from the two-particle correlation between identified triggers (pions (${\pi }^{\pm }$) , protons (p/$\bar{p}$))) and un-identified charged particles at intermediate transverse momentum ($p_T$) in p-Pb collisions at $\sqrt{s_{NN}}=$ 5.02 TeV have been presented. The events generated from a hybrid Monte-Carlo event generator, EPOS 3.107 that implements a flux-tube initial conditions followed by event by event 3+1D viscous hydrodynamical evolution, have been analysed to calculate two-dimensional correlation functions in $\Delta \eta$-$\Delta \varphi$. The strength of angular correlations at small relative angles (jet-like correlations), quantified in terms of near-side jet-like per-trigger yield has been calculated as a function of the event multiplicity. The yield associated with pion triggers exhibit negligible multiplicity dependence, while the proton-triggered yield shows a gradual suppression from low to high multiplicity events. In small collision systems like p-Pb where jet modification is expected to be less dominant, the observed suppression may be associated with the hydrodynamical evolution of the bulk system that generates an outward radial flow. Analogous measurements in Au-Au collisions at RHIC energy have shown a hint of dilution in proton-triggered correlation at its highest multiplicity suggesting that the soft physics processes in p-Pb and heavy ion collisions may have qualitative similarity.

    ↳ nucl-exhep-exhep-phPLB(2016)·10 citations
19. 19*

    From inflation to black hole mergers and back again: Gravitational-wave data-driven constraints on inflationary scenarios with a first-principle model of primordial black holes across the QCD epoch

    G. Franciolini🇮🇹 · I. Musco🇮🇹 · P. Pani🇮🇹 · A. Urbano🇮🇹

    Recent population studies have searched for a subpopulation of primordial black holes (PBHs) in the gravitational-wave (GW) events so far detected by LIGO/Virgo/KAGRA (LVK), in most cases adopting a phenomenological PBH mass distribution. When deriving such population from first principles in the standard scenario, however, the equation of state of the Universe at the time of PBH formation may strongly affect the PBH abundance and mass distribution, which ultimately depend on the power spectrum of cosmological perturbations. Here we improve on previous population studies on several aspects: (i) we adopt state-of-the-art PBH formation models describing the collapse of cosmological perturbations across the QCD epoch; (ii) we perform the first Bayesian multi-population inference on GW data including PBHs and directly using power spectrum parameters instead of phenomenological distributions; (iii) we critically confront the PBH scenario with LVK phenomenological models describing the GWTC-3 catalog both in the neutron-star and in the BH mass ranges, also considering PBHs as subpopulation of the total events. Our results confirm that LVK observations prevent the majority of the dark matter to be in the form of stellar mass PBHs. We find that the best fit PBH model can comprise a small fraction of the total events, in particular it can naturally explain events in the mass gaps. If the lower mass-gap event GW190814 is interpreted as a PBH binary, we predict that LVK should detect up to a few subsolar mergers and one to $\approx 30$ lower mass gap events during the upcoming O4 and O5 runs. Finally, mapping back the best-fit power spectrum into an ultra slow-roll inflationary scenario, we show that the latter predicts detectable PBH mergers in the LVK band, a stochastic GW background detectable by current and future instruments, and may include the entirety of dark matter in asteroid-mass PBHs.

    ↳ astro-ph.COgr-qchep-phhep-thPRD(2022)·149 citations
20. 20*

    The Sigma-8 Tension is a Drag

    Vivian Poulin🇫🇷 · José Luis Bernal🇺🇸 · Ely Kovetz🇮🇱 · Marc Kamionkowski🇺🇸

    Measurements of weak gravitational lensing at low redshifts ($z\lesssim 0.5-1$), quantified by the parameter $S_8$, favor weaker matter clustering than that expected from the standard $\Lambda$CDM cosmological model with parameters determined by cosmic microwave background (CMB) measurements. However, the amplitude of matter clustering at higher redshifts, as probed by lensing of the CMB, is consistent with $\Lambda$CDM. This apparent paradox suggests a connection between the $S_8$ tension and the transition from matter to dark-energy domination. Here we show that the tension can be resolved by introducing a friction between dark matter and dark energy without altering the tightly constrained expansion history. The low-$S_8$ measurements favor (at $\gtrsim 3\sigma$, in this one parameter model) a non-zero drag leading to a suppression of low-redshift power right around the transition from matter to dark-energy domination. We suggest ways to further probe the scenario.

    ↳ astro-ph.COhep-phhep-thPRD(2023)·135 citations
21. 21*

    Decay of the $\Lambda (1405)$ Hyperon to ${\Sigma }^0{\pi }^0$ Measured at GlueX

    Nilanga Wickramaarachchi🇺🇸 · Reinhard A. Schumacher🇺🇸 · Grzegorz Kalicy (for the GlueX Collaboration)🇺🇸

    Among the light baryons, the $J^{\pi }={\frac{1}{2}}^{-}$ $\Lambda (1405)$ hyperon is an important special case as it sits just below the $N\bar{K}$ threshold and decays almost exclusively to $\Sigma \pi$. Some long-standing hypotheses for $\Lambda (1405)$ are that it could be a $N\bar{K}$ bound state or a $\Sigma \pi$ continuum resonance. It may also be considered as a simple quark-model resonance, the $P$-wave companion of the $\Lambda (1520)$. In recent years chiral unitary models have suggested that there are two isospin zero poles present in this mass region, and that the "line shape" of the $\Lambda (1405)$ depends to what extent each of the two poles are stimulated in a given reaction. Below the $N\bar{K}$ threshold, the $\Lambda (1405)$ decays to the three $\Sigma \pi$ charge combinations. The ${\Sigma }^0{\pi }^0$ mode is purely $I=0$ and it is uncontaminated by complications arising from $I=1$ scattering processes contributing to the reaction mechanism in the ${\Sigma }^{+}{\pi }^{-}$ and ${\Sigma }^{-}{\pi }^{+}$ decays. It is also not affected from production and decay of the nearby ${\Sigma }^0(1385)$ hyperon. The GlueX experiment at Jefferson Lab has been used to study the $\Lambda (1405)\to {\Sigma }^0{\pi }^0$ decay mode. We focus on the preliminary results of $d\sigma /d{M}_{{\Sigma }^0{\pi }^0}$ and fits to the line shape of the $\Lambda (1405)$ region in the $-(t-t_{min})$ range 0 - 1.5 GeV${}^2$ from analyzing the reaction $\gamma p\to K^{+}{\Lambda }^{\ast }$ using the data collected during the first phase of the GlueX program.

    ↳ nucl-exhep-exhep-phEPJ Web Conf.(2022)·20 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.