Wed·Mar 22, 2023Wednesday·March 22, 2023

1. 01*

   The Strong Force meets the Dark Sector: a robust estimate of QCD uncertainties for anti-matter dark matter searches

   Adil Jueid🇰🇷 · Jochem Kip🇳🇱 · Roberto Ruiz de Austri🇪🇸 · Peter Skands🇦🇺

   In dark-matter annihilation channels to hadronic final states, stable particles -- such as positrons, photons, antiprotons, and antineutrinos -- are produced via complex sequences of phenomena including QED/QCD radiation, hadronisation, and hadron decays. These processes are normally modelled by Monte Carlo event generators whose limited accuracy imply intrinsic QCD uncertainties on the predictions for indirect-detection experiments like Fermi-LAT, Pamela, IceCube or AMS-02. In this article, we perform a complete analysis of QCD uncertainties in antimatter spectra from dark-matter annihilation, based on parametric variations of the Pythia 8 event generator. After performing several retunings of light-quark fragmentation functions, we define a set of variations that span a conservative estimate of the QCD uncertainties. We estimate the effects on antimatter spectra for various annihilation channels and final-state particle species, and discuss their impact on fitted values for the dark-matter mass and thermally-averaged annihilation cross section. We find dramatic impacts which can go up to $\mathcal{O}(40)$ GeV for uncertainties on the dark-matter mass and up to $\mathcal{O}(10\%)$ for the annihilation cross section. We provide the spectra in tabulated form including QCD uncertainties and code snippets to perform fast dark-matter fits, in this https://github.com/ajueid/qcd-dm.github.io.git repository.

   hep-phastro-ph.HEJHEP(2024)·22 citations
2. 02*

   Axion-sourced fireballs from supernovae

   Melissa Diamond🇨🇦 · Damiano F. G. Fiorillo🇩🇰 · Gustavo Marques-Tavares🇺🇸 · Edoardo Vitagliano🇮🇱

   New feebly interacting particles would emerge from a supernova core with 100-MeV-range energies and produce $\gamma$-rays by subsequent decays. These would contribute to the diffuse cosmic $\gamma$-ray background or would have shown up in the Solar Maximum Mission (SMM) satellite from SN~1987A. However, we show for the example of axion-like particles (ALPs) that, even at distances beyond the progenitor star, the decay photons may not escape, and can instead form a fireball, a plasma shell with $T\lesssim 1$ MeV. Thus, existing arguments do not exclude ALPs with few 10 MeV masses and a two-photon coupling of a few $10^{-10}{\mathrm{GeV}}^{-1}$. However, the energy would have showed up in sub-MeV photons, which were not seen from SN 1987A in the Pioneer Venus Orbiter (PVO), closing again this new window. A careful re-assessment is required for other particles that were constrained in similar ways.

   hep-phastro-ph.HEPRD(2023)·104 citations
3. 03*

   Structure of Nucleons and Their Interaction in the Concept of Nonperturbative QCD as a Pressing Issue of 21st-Century Physics

   Vladimir I. Komarov🇷🇺

   The problem of the structure of nucleons and their interaction in the concept of nonperturbative QCD is discussed as an approach to studying the transformation of current quarks into constituent ones and the search for the mechanism of such a transformation, creating the bulk of the nucleon mass. Attention is drawn to the possibilities offered by studying central nucleon-nucleon collisions in this aspect.

   hep-phnucl-exnucl-thPhys.Part.Nucl.Lett.(2022)·1 citation
4. 04*

   Light quark and antiquark constraints from new electroweak data

   Alberto Accardi🇺🇸 · Xiaoxian Jing🇺🇸 · Joseph Francis Owens🇺🇸 · Sanghwa Park🇺🇸

   We present a new parton distribution function analysis which includes new data for W boson production in proton-proton collisions and lepton pair production in proton-proton and proton-deuteron collisions. The new data provide strong constraints on the light antiquark parton distribution functions in the proton. We identify an interesting correlation between the $d/u$ ratio and the $\bar{d}/\bar{u}$ ratio which leads to a modification of our previous results for the $d/u$ ratio as the parton momentum fraction $x\to 1.$

   hep-phhep-exnucl-thPRD(2023)·24 citations
5. 05*

   Gravitational transverse-momentum distributions

   Cédric Lorcé🇫🇷 · Qin-Tao Song🇨🇳

   We study the energy-momentum tensor of spin-$0$ and spin-$\frac{1}{2}$ hadrons in momentum space. We parametrize this object in terms of so-called gravitational transverse-momentum distributions, and we identify in the quark sector the relations between the latter and the usual transverse-momentum distributions. Focusing on particular components of the energy-momentum tensor, we study momentum densities, flux of inertia and stress distribution in momentum space, revealing part of the wealth of physical information that can be gained from higher-twist transverse-momentum distributions.

   hep-phhep-exhep-latnucl-thPLB(2023)·13 citations
6. 06*

   On the possibility of mixed axion/neutralino dark matter in specific SUSY DFSZ axion models

   Zhong-Jun Yang🇨🇳 · Tai-Fu Feng🇨🇳 · Xing-Gang Wu🇨🇳

   We introduce four supersymmetric (SUSY) axion models in which the strong CP problem and the $\mu$ problem are solved with the help of the Peccei-Quinn mechanism and the Kim-Nilles mechanism, respectively. The axion physics enriches the SUSY model by introducing axion as a dark matter candidate and, therefore, the lightest supersymmetric particle (LSP) could just be a part of the total dark matter. For this reason, axion relieves the tensions between SUSY models and numerous experimental measurements, such as the dark matter direct detection experiments and the precise measurements of anomalous magnetic moment of the muon $a_{\mu }$. In the present paper, we investigate the constraints imposed by the latest $a_{\mu }$ measurements and LUX-ZEPLIN (LZ) experiment on the relic density of the Higgsino-like LSP. Additionally, we consider the constraints arising from the cosmology of saxions and axinos, and their impacts on the parameter space of our models are carefully examined. For the axion constituting the remaining portion of dark matter, we find that the conventional misalignment mechanism can successfully account for the correct dark matter relic density observed by the Planck satellite.

   hep-phComments Nucl.Part.Phys.(2024)·2 citations
7. 07*

   The recursive structure of Baikov representations I: generics and application to symbology

   Xuhang Jiang🇨🇳 · Li Lin Yang🇨🇳

   In this paper, we explore the recursive structure of Baikov representations for Feynman integrals. We demonstrate that the various Baikov representations for all sectors of an integral family can be organized in a tree-like structure. Using this structure, we show that the symbol letters of one-loop Feynman integrals can be written in terms of minors of a matrix associated with the top sector. Non-trivial relations among these symbol letters can then be easily discovered using results from linear algebra.

   hep-phhep-thPRD(2023)·19 citations
8. 08*

   Non-perturbative Generation of Light Antiquark Flavor Asymmetry in Proton

   Shweta Choudhary🇮🇳 · Pranjal Srivastava🇮🇳 · Harleen Dahiya🇮🇳

   We compute the light antiquark flavor asymmetry in the proton using the Chiral Quark Model (${\chi }_{\mathrm{QM}}$). The distribution functions for the light antiquarks $\bar{d}(x)$ and $\bar{u}(x)$ have been extracted with the help of experimental data from NuSea/E866 and HERMES for the Bjorken$-x$ range $0.015<x<0.35$ as well from the most recent SeaQuest data for an extended $x$ range $0.13<x<0.45$. Our results on the $\bar{d}(x)-\bar{u}(x)$, $\frac{\bar{d}(x)}{\bar{u}(x)}$ and Gottfried Integral $I_G$ are in agreement with the experimental data and confirm the presence of enhanced $\bar{d}$ sea whose origin is purely non-perturbative based on chiral symmetry breaking in QCD.

   hep-ph2 citations
9. 09*

   A spatially constrained QCD colour reconnection in pp, pA, and AA collisions in the PYTHIA8/Angantyr model

   Leif Lönnblad🇸🇪 · Harsh Shah🇸🇪

   We present an updated version of the QCD-based colour reconnection model in PYTHIA8, where we constrain the range in impact parameter for which reconnections are allowed. In this way, we can introduce more realistic colour reconnections in the Angantyr model for heavy ion collisions, where previously only reconnections within separate nucleon sub-collisions have been allowed. We investigate how the new impact parameter constraint influences final states in pp collisions, and retune parameters of the multi-parton interaction parameters in PYTHIA to compensate so that minimum bias data are reproduced. We also study multiplicity distributions in pA collisions and find that, in order to counteract the loss in multiplicity due to the introduction of global colour reconnections, we need to modify some parameters in the Angantyr model while keeping the parameters tuned to pp fixed. With Angantyr we can then extrapolate to AA collisions without further parameter tuning and retaining a reasonable description of the basic multiplicity distributions.

   hep-phEPJC(2023)·20 citations
10. 10*

    Novel Method to Reliably Determine the QCD Coupling from $R_{\mathrm{uds}}$ Measurements and its effects to Muon $g-2$ and $\alpha (M_Z^2)$ within the Tau-Charm Energy Region

    Jian-Ming Shen🇨🇳 · Bing-Hai Qin🇨🇳 · Jiang Yan🇨🇳 · Sheng-Quan Wang🇨🇳 · Xing-Gang Wu🇨🇳

    We present a novel method for precisely determining the QCD running coupling from $R_{\mathrm{uds}}$ measurements in electron-positron annihilation. When calculating the fixed-order perturbative QCD (pQCD) approximant of $R_{\mathrm{uds}}$, its effective coupling constant ${\alpha }_s(Q_{\ast }^2)$ is determined by using the principle of maximum conformality, a systematic scale-setting method for gauge theories, whose resultant pQCD series satisfies all the requirements of renormalization group. Contribution due to the uncalculated higher-order (UHO) terms is estimated by using the Bayesian analysis. Using $R_{\mathrm{uds}}$ data measured by the KEDR detector at $22$ centre-of-mass energies between $1.84$ GeV and $3.72$ GeV, we obtain ${\alpha }_s(M_Z^2)=0.1227_{-0.0132}^{+0.0117}(exp.)\pm 0.0016(the.)$, where the theoretical uncertainty (the.) is negligible compared to the experimental one (exp.). Numerical analyses confirm that the new method for calculating $R_{\mathrm{uds}}$ removes conventional renormalization scale ambiguity, and the residual scale dependence due to the UHO-terms will also be highly suppressed due to a more convergent pQCD series. This leads to a significant stabilization of the perturbative series, and a significant reduction of theoretical uncertainty. It thus provides a reliable theoretical basis for precise determination of the QCD running coupling from $R_{\mathrm{uds}}$ measurements at future Tau-Charm Facility. It can also be applied for the precise determination of the hadronic contributions to muon $g-2$ and QED coupling $\alpha (M_Z^2)$ within the tau-charm energy range.

    hep-phJHEP(2023)·13 citations
11. 11*

    The mass spectrum and strong decay properties of the charmed-strange mesons within Godfrey-Isgur model considering the coupled-channel effects

    Jing-Jing Yang🇨🇳 · Wei Hao🇨🇳 · Xiaoyu Wang🇨🇳 · De-Min Li🇨🇳 · Yu-Xiao Li🇨🇳 · En Wang🇨🇳

    Motivated by the recently observed $D_{s0}(2590)$ state by LHCb, we investigate the mass spectrum and the strong decay properties of the charmed-strange mesons within Godfrey-Isgur model considering the coupled-channel effects. Our results support that $D_{s0}^{\ast }(2317)$ and $D_{s1}(2460)$ can be interpreted as the $D_s(1^3{P}_0)$ and $D_s(1^3{P}_1)$ states with larger $DK$ and $D^{\ast }K$ components, respectively, and $D_{s1}(2700)$, $D_{s1}(2536)$, $D_{s2}^{\ast }(2573)$, $D_{s1}^{\ast }(2860)$, $D_{s3}^{\ast }(2860)$, and $D_{sJ}^{\ast }(3040)$ can be well interpreted as the $D_s(2^3{S}_1)$, $D_s(1^1{P}_1)$, $D_s(1^3{P}_2)$, $D_s(1^3{D}_1)$, $D_s(1^3{D}_3)$, and $D_s(2^1{P}_1)$ states, respectively. Although, $D_{s0}(2590)$ mass is about 50 MeV less than our prediction for the $D_s(2^1{S}_0)$ state, its width is still in good agreement with the one of $D_s(2^1{S}_0)$. Therefore, $D_{s0}(2590)$ state needs to be further confirmed by the experimental measurements, and the more precise information about $D_{s0}(2590)$ will shed light on its assignment of $D_s(2^1{S}_0)$. Furthermore, we predict the masses and the strong decay properties of the charmed-strange mesons with masses around 3 GeV, which would be helpful to experimentally search for these states.

    hep-phEPJC(2023)·14 citations
12. 12*

    Critical dynamics in a real-time formulation of the functional renormalization group

    Johannes V. Roth🇩🇪 · Lorenz von Smekal🇩🇪

    We present first calculations of critical spectral functions of the relaxational Models A, B, and C in the Halperin-Hohenberg classification using a real-time formulation of the functional renormalization group (FRG). We revisit the prediction by Son and Stephanov that the linear coupling of a conserved density to the non-conserved order parameter of Model A gives rise to critical Model-B dynamics. We formulate both 1-loop and 2-loop self-consistent expansion schemes in the 1PI vertex functions as truncations of the effective average action suitable for real-time applications, and analyze in detail how the different critical dynamics are properly incorporated in the framework of the FRG on the closed-time path. We present results for the corresponding critical spectral functions, extract the dynamic critical exponents for Models A, B, and C, in two and three spatial dimensions, respectively, and compare the resulting values with recent results from the literature.

    hep-phJHEP(2023)·30 citations
13. 13*

    Asymmetric dark matter with a spontaneously broken $U(1{)}^{\prime }$: self-interaction and gravitational waves

    Zien Chen🇨🇳 · Kairui Ye🇨🇳 · Mengchao Zhang🇨🇳

    Motivated by the collisionless cold dark matter small scale structure problem, we propose an asymmetric dark matter model where dark matter particle interact with each other via a massive dark gauge boson. This model easily avoid the strong limits from cosmic microwave background (CMB) observation, and have a large parameter space to be consistent with small scale structure data. We focus on a special scenario where portals between dark sector and visible sector are too weak to be detected by traditional methods. We find that this scenario can increase the effective number of neutrinos ($N_{\text{eff}}$).In addition, the spontaneous $U(1{)}^{\prime }$ symmetry breaking process, which makes dark gauge boson massive, can generate stochastic gravitational waves with peak frequency around $10^{-6}-10^{-7}\text{ Hz}$.

    hep-phPRD(2023)·21 citations
14. 14*

    Shedding light on shadow generalized parton distributions

    Eric Moffat🇺🇸 · Adam Freese🇺🇸 · Ian Cloët🇺🇸 · Thomas Donohoe🇺🇸 · Leonard Gamberg🇺🇸 · Wally Melnitchouk🇺🇸 · Andreas Metz🇺🇸 · Alexei Prokudin🇺🇸 · Nobuo Sato🇺🇸

    The feasibility of extracting generalized parton distributions (GPDs) from deeply-virtual Compton scattering (DVCS) data has recently been questioned because of the existence of an infinite set of so-called ''shadow GPDs'' (SGPDs). These SGPDs depend on the process and manifest as multiple solutions (at a fixed scale $Q^2$) to the inverse problem that needs to be solved to infer GPDs from DVCS data. SGPDs therefore pose a significant challenge for extracting GPDs from DVCS data. With this motivation we study the extent to which QCD evolution can provide constraints on SGPDs. This is possible because the known classes of SGPDs begin to contribute to observables after evolution, and can then be constrained (at the input scale $Q_0^2$) by data that has a finite $Q^2$ range. The impact that SGPDs could have on determining the total angular momentum, pressure and sheer force distributions, and tomography is also discussed. Our key finding is that scale evolution, coupled with data over a wide range of skewness $\xi$ and $Q^2$, can constrain the class of SGPDs that we studied and potentially make possible the extraction of GPDs from DVCS data over a limited range in the GPD variables.

    hep-phnucl-exnucl-thPRD(2023)·51 citations
15. 15*

    Isospin symmetry and analyticity in $D\to \bar{K}\pi \pi$ decays

    Emi Kou🇫🇷 · Tetiana Moskalets🇩🇪 · Bachir Moussallam🇫🇷

    We perform a detailed study of the consequences of isospin symmetry in the Cabibbo favoured $D\to \text{Kbar}\pi \pi$ decays. These processes are important for precision testing of the Standard Model and for hadronic physics. Combining isospin symmetry with a dispersive reconstruction theorem we derive a representation in terms of one-variable functions which allows one to predict all the $D\to \text{Kbar}\pi \pi$ amplitudes given inputs from one $D^{+}$ mode and one $D^0$ mode. From this, using dispersion relations and unitarity, we derive a set of 6+6 Khuri-Treiman type integral equations which enable to take three-body rescattering effects into account. A first test of this approach is presented using experimental results on the $D^{+}\to K_S\text{piz}\text{pip}$ and the $D^0\to K_S\text{pim}\text{pip}$ modes.

    hep-phhep-exJHEP(2023)·7 citations
16. 16*

    The CMS di-photon excess at 95 GeV in view of the LHC Run 2 results

    T. Biekötter🇩🇪 · S. Heinemeyer🇪🇸 · G. Weiglein🇩🇪

    The CMS collaboration has recently reported the results of a low-mass Higgs-boson search in the di-photon final state based on the full Run 2 data set with refined analysis techniques. The new results show an excess of events at a mass of about 95 GeV with a local significance of $2.9\sigma$, confirming a previously reported excess at about the same mass and similar significance based on the first-year Run 2 plus Run 1 data. The observed excess is compatible with the limits obtained in the corresponding ATLAS searches. In this work, we discuss the di-photon excess and show that it can be interpreted as the lightest Higgs boson in the Two-Higgs doublet model that is extended by a complex singlet (S2HDM) of Yukawa types II and IV. We show that the second-lightest Higgs boson is in good agreement with the current LHC Higgs-boson measurements of the state at 125 GeV, and that the full scalar sector is compatible with all theoretical and experimental constraints. Furthermore, we discuss the di-photon excess in conjunction with an excess in the $b\bar{b}$ final state observed at LEP and an excess observed by CMS in the di-tau final state, which were found at comparable masses with local significances of about $2\sigma$ and $3\sigma$, respectively. We find that the $b\bar{b}$ excess can be well described together with the di-photon excess in both types of the S2HDM. However, the di-tau excess can only be accommodated at the level of $1\sigma$ in type IV. We also comment on the compatibility with supersymmetric scenarios and other extended Higgs sectors, and we discuss how the potential signal can be further analyzed at the LHC and at future $e^{+}{e}^{-}$ colliders.

    hep-phPLB(2023)·78 citations
17. 17*

    Photoproduction of $J/\psi$ with neutron tagging in ultra-peripheral collisions of nuclei at RHIC and the LHC

    E. Kryshen (St. Petersburg, INP)🇷🇺 · M. Strikman (Penn State U.)🇺🇸 · M. Zhalov (St. Petersburg, INP)🇷🇺

    We present predictions for the cross sections of the coherent and incoherent $J/\psi$ photoproduction in ultra-peripheral collisions at RHIC and at the LHC calculated for different classes of events depending on the presence of neutrons emitted by colliding nuclei. Since strong nucleus-nucleus interactions in UPCs are suppressed, it is usually assumed that neutrons at forward rapidities originate mainly from the electromagnetic dissociation of colliding nuclei caused by additional photon exchanges. This is a reasonable assumption for the coherent photoproduction where the state of the target nucleus remains intact. We consider additional sources of neutrons in the incoherent quasielastic and nucleon dissociative $J/\psi$ photoproduction and show that these processes significantly change probabilities of neutron emission compared to calculations when only neutrons from electromagnetic dissociation of nuclei are considered. Such studies should allow one to explore the dynamics of nuclear shadowing in the incoherent $J/\psi$ photoproduction down to $x\sim 10^{-5}$.

    hep-phhep-exnucl-exPRC(2023)·14 citations
18. 18*

    Dark Matter spikes around Sgr A* in $\gamma$-rays

    Shyam Balaji🇫🇷 · Divya Sachdeva🇫🇷 · Filippo Sala🇮🇹 · Joseph Silk🇫🇷

    We use H.E.S.S. $\gamma$-ray observations of Sgr A* to derive novel limits on the Dark Matter (DM) annihilation cross-section. We quantify their dependence on uncertainties i) in the DM halo profile, which we vary from peaked to cored, and ii) in the shape of the DM spike around Sgr A*, dynamically heated by the nuclear star cluster. For peaked halo profiles and depending on the heating of the spike, our limits are the strongest existing ones for DM masses above a few TeV. Our study contributes to assessing the influence of the advancements in our knowledge of the Milky Way on determining the properties of DM particles.

    hep-phastro-ph.HEJCAP(2023)·40 citations
19. 19*

    Non-perturbative particle production and differential geometry

    Tomohiro Matsuda🇯🇵

    This paper proposes a basic method for understanding stationary particle production on manifolds by means of the Stokes phenomenon. We studied the Stokes phenomena of the Schwinger effect, the Unruh effect and Hawking radiation in detail focusing on the origin of their continuous particle production. We found a possibility that conventional calculations may not explain the experimental results.

    ↳ hep-thgr-qchep-phInt.J.Mod.Phys.A(2023)·4 citations
20. 20*

    Barrow nearly-extensive Gibbs-like entropy favoured by the full dynamical and geometrical data set in cosmology

    Tomasz Denkiewicz🇵🇱 · Vincenzo Salzano🇵🇱 · Mariusz P. Dabrowski

    We apply the full set of most update dynamical and geometrical data in cosmology to the nonextensive Barrow entropic holographic dark energy. We show that the data point towards an extensive Gibbs-like entropic behaviour for the cosmological horizons, which is the extreme case of the Barrow entropy, with the entropy parameter being $\Delta >0.86$, close to the maximum threshold of $\Delta =1$ where the fractal dimension of the area-horizon becomes almost or just the volume and the intensivity is recovered. Futhermore, we find that the standard Bekenstein area-entropy limit ($\Delta =0$) is excluded by the set of our data. This contradicts the bounds obtained recently from early universe tests such as the baryon asymmetry, the big-bang nucleosynthesis, and the inflation limiting $\Delta <0.008$ at the most extreme case.

    ↳ astro-ph.COgr-qchep-phPRD(2023)·12 citations
21. 21*

    Searching for Time-Dependent Axion Dark Matter Signals in Pulsars

    R. A. Battye🇬🇧 · M. J. Keith🇬🇧 · J. I. McDonald🇧🇪 · S. Srinivasan🇬🇧 · B. W. Stappers🇬🇧 · P. Weltevrede🇬🇧

    Axion dark matter can be converted into photons in the magnetospheres of neutron stars leading to a spectral line centred on the Compton wavelength of the axion. Due to the rotation of the star and the plasma effects in the magnetosphere the signal is predicted to be periodic with significant time variation - a unique smoking gun for axion dark matter. As a proof of principle and to develop the methodology, we carry out the first time domain search of the signal using data from PSR J2144$-$3933 taken as part of the MeerTIME project on MeerKAT telescope. We search for specific signal templates using a matched filter technique and discuss when a time-domain analysis (as is typically the case in pulsar observations) gives greater sensitivity to the axion-coupling to photons in comparison to a simple time-averaged total flux study. We do not find any candidate signals and, hence, impose an upper limit on the axion-to-photon coupling of $g_{a\gamma \gamma }<4\times 10^{-11}{\mathrm{GeV}}^{-1}$ over the mass range $m_{\mathrm{a}}=3.9-4.7\mu \mathrm{eV}$ using this data. This limit relies on PSR J2144$-$3933 not being an extremely aligned rotator, as strongly supported by simple arguments based on the observed pulse profile width. We discuss the possibilities of improving this limit using future observations with MeerKAT and also SKA1-mid and the possibility of using other objects. Finally, to evade modelling uncertainties in axion radio signals, we also carry out a generic ``any periodic-signal search" in the data, finding no evidence for an axion signal.

    ↳ astro-ph.COastro-ph.HEgr-qchep-phPRD(2023)·51 citations
22. 22*

    Dark Matter Minihalos from Primordial Magnetic Fields

    Pranjal Ralegankar🇺🇸

    Primordial magnetic fields (PMF) can enhance baryon perturbations on scales below the photon mean free path. However, a magnetically driven baryon fluid becomes turbulent near recombination, thereby damping out baryon perturbations below the turbulence scale. In this Letter, we show that the initial growth in baryon perturbations gravitationally induces growth in the dark matter perturbations, which are unaffected by turbulence and eventually collapse to form $10^{-11}-10^3{M}_{\odot }$ dark matter minihalos. If the magnetic fields purportedly detected in the blazar observations are PMFs generated after inflation and have a Batchelor spectrum, then such PMFs could potentially produce dark matter minihalos.

    ↳ astro-ph.COhep-phPRL(2023)·19 citations
23. 23*

    Two-beam laser photon merging

    Chantal Sundqvist🇩🇪 · Felix Karbstein🇩🇪

    Quasi-elastic scattering processes have long been thought of providing the most promising signal for a first experimental detection of quantum vacuum nonlinearity. A prominent example of such a process is vacuum birefringence. However, these signals are typically strongly background dominated. This problem can be circumvented by inelastic scattering processes. In this study, we investigate the inelastic process of laser photon merging in the collision of just two laser pulses under a finite angle, which provides signal photons of a distinct frequency outside the frequency spectrum of the background. As a key result, for the example of two laser beams of the same oscillation frequency we demonstrate that by using high-intensity optical lasers and choosing an optimal collision angle, photon merging should become accessible in experiment with state-of-the-art technology. In this case three frequency $\omega$ laser photons are merged to a single $3\omega$ photon.

    ↳ physics.opticshep-phPRD(2023)·8 citations
24. 24*

    Relic gravitons and high-frequency detectors

    Massimo Giovannini🇨🇭

    Cosmic gravitons are expected in the MHz-GHz regions that are currently unreachable by the operating wide-band interferometers and where various classes of electromechanical detectors have been proposed through the years. The minimal chirp amplitude detectable by these instruments is often set on the basis of the sensitivities reachable by the detectors currently operating in the audio band. By combining the observations of the pulsar timing arrays, the limits from wide-band detectors and the other phenomenological bounds we show that this requirement is far too generous and even misleading since the actual detection of relic gravitons well above the kHz would demand chirp and spectral amplitudes that are ten or even fifteen orders of magnitude smaller than the ones currently achievable in the audio band, for the same classes of stochastic sources. We then examine more closely the potential high-frequency signals and show that the sensitivity in the chirp and spectral amplitudes must be even smaller than the ones suggested by the direct and indirect constraints on the cosmic gravitons. We finally analyze the high-frequency detectors in the framework of Hanbury-Brown Twiss interferometry and argue that they are actually more essential than the ones operating in the audio band (i.e. between few Hz and few kHz) if we want to investigate the quantumness of the relic gravitons and their associated second-order correlation effects. We suggest, in particular, how the statistical properties of thermal and non-thermal gravitons can be distinguished by studying the corresponding second-order interference effects.

    ↳ gr-qcastro-ph.COhep-exhep-ph+1JCAP(2023)·24 citations
25. 25*

    One-loop Corrections in Power Spectrum in Single Field Inflation

    Hassan Firouzjahi🇮🇷

    We revisit the one-loop correction in curvature perturbation power spectrum in models of single field inflation which undergo a phase of ultra slow-roll (USR) inflation. We include the contributions from both the cubic and quartic interaction Hamiltonians and calculate the one-loop corrections on the spectrum of the CMB scale modes from the small scale modes which leave the horizon during the USR phase. It is shown that the amplitude of one-loop corrections depends on the sharpness of the transition from the USR phase to the final slow-roll phase. For an arbitrarily sharp transition, the one-loop correction becomes arbitrarily large, invalidating the perturbative treatment of the analysis. We speculate that for a mild transition, the large one-loop corrections are washed out during the subsequent evolution after the USR phase. The implications for primordial black holes formation are briefly reviewed.

    ↳ astro-ph.COgr-qchep-phhep-thJCAP(2023)·122 citations
26. 26*

    A Comparative Analysis between Unbiased Exponential Resummation and Taylor Expansion in Finite-Density QCD with a new phasefactor for Isospin

    Sabarnya Mitra🇮🇳

    The recently introduced unbiased exponential resummation at finite chemical potential has become an important approach which promises to capture reliably the behaviour of higher order conserved charge cumulants appearing otherwise in the finite-density QCD Taylor series of thermodynamic observables. In this paper, we present a thorough analysis of the estimates of charge cumulants upto eighth order and have compared them using Taylor expansion method and unbiased exponential resummation approach for baryon and isospin chemical potentials. We also subsequently compare the different estimates of the radius of convergence obtained using these two methods and check if the zeros of phasefactor for baryochemical potential can indicate something about these estimated values. We propose a new method of finding a non-trivial phasefactor for isospin chemical potential and we attempt explaining the different estimates of radius of convergence from the zeroes of this newly constructed gauge-ensemble average phasefactor for isospin chemical potential. Lastly, we also illustrate kurtosis plots describing the behaviour of overlap problem in isospin chemical potential and check if it maintains consistency with the appearance of zeros of the newly proposed phasefactor.

    ↳ hep-lathep-phnucl-exnucl-th1 citation
27. 27*

    The QED four-photon amplitudes off-shell: part 2

    Naser Ahmadiniaz🇩🇪 · Cristhiam Lopez-Arcos🇨🇴 · Misha A. Lopez-Lopez🇩🇪 · Christian Schubert🇨🇿

    This is the second one of a series of four papers devoted to a first calculation of the scalar and spinor QED four-photon amplitudes completely off-shell. We use the worldline formalism which provides a gauge-invariant decomposition for these amplitudes as well as compact integral representations. It also makes it straightforward to integrate out any given photon leg in the low-energy limit, and in the present sequel we do this with two of the four photons. For the special case where the two unrestricted photon momenta are equal and opposite the information on these amplitudes is also contained in the constant-field vacuum polarisation tensors, which provides a check on our results. Although these amplitudes are finite, for possible use as higher-loop building blocks we evaluate all integrals in dimensional regularisation. As an example, we use them to construct the two-loop vacuum polarisation tensors in the low-energy approximation, rederive from those the two-loop $\beta$-function coefficients and analyse their anatomy with respect to the gauge-invariant decomposition. As an application to an external-field problem, we provide a streamlined calculation of the Delbrück scattering amplitudes in the low-energy limit. All calculations are done in parallel for scalar and spinor QED.

    ↳ hep-thhep-phNPB(2023)·16 citations
28. 28*

    Do the CMB Temperature Fluctuations Conserve Parity?

    Oliver H. E. Philcox🇺🇸

    Observations of the Cosmic Microwave Background (CMB) have cemented the notion that the large-scale Universe is both statistically homogeneous and isotropic. But is it invariant also under reflections? To probe this we require parity-sensitive statistics: for scalar observables, the simplest is the trispectrum. We make the first measurements of the parity-odd scalar CMB, focusing on the large-scale ($2<\ell <510$) temperature anisotropies measured by Planck. This is facilitated by new quasi-maximum-likelihood estimators for binned correlators, which account for mask convolution and leakage between even- and odd-parity components, and achieve ideal variances within $\approx 20\%$. We perform a blind test for parity violation by comparing a ${\chi }^2$ statistic from Planck to theoretical expectations, using two suites of simulations to account for the possible likelihood non-Gaussianity and residual foregrounds. We find consistency at the $\approx 0.4\sigma$ level, yielding no evidence for novel early-Universe phenomena. The measured trispectra allow for a wealth of new physics to be constrained; here, we use them to constrain eight primordial models, including Ghost Inflation, Cosmological Collider scenarios, and Chern-Simons gauge fields. We find no signatures of new physics, with a maximal detection significance of $2.0\sigma$. Our results also indicate that the recent parity excesses seen in the BOSS galaxy survey are not primordial in origin, given that the CMB dataset contains roughly $250\times$ more primordial modes, and is far easier to interpret, given the linear physics, Gaussian statistics, and accurate mocks. Tighter CMB constraints can be wrought by including smaller scales and adding polarization data.

    ↳ astro-ph.COgr-qchep-exhep-ph+1PRL(2023)·56 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.