Thu·Apr 21, 2022Thursday·April 21, 2022

1. 01*

   Light-cone distribution amplitudes of heavy mesons with QED effects

   Martin Beneke🇩🇪 · Philipp Böer🇩🇪 · Jan-Niklas Toelstede🇩🇪 · Keri K. Vos🇳🇱

   We discuss the QED-generalized leading-twist light-cone distribution amplitudes of heavy mesons, that appear in QCD$\times$QED factorization theorems for exclusive two-body $B$ decays. In the presence of electrically charged particles, these functions should be more appropriately regarded as soft functions for heavy-meson decays into two back-to-back particles. In this paper, we derive the one-loop anomalous dimension of these soft functions and study their behaviour under renormalization-scale evolution, obtaining an exact solution in Laplace space. In addition, we provide numerical solutions for the soft functions and analytical solutions to all orders in the strong and to first order in the electromagnetic coupling. For the inverse (and inverse-logarithmic) moments, we obtain an all-order solution in both couplings. We further provide numerical estimates for QED corrections to the inverse moments.

   hep-phJHEP(2022)·32 citations
2. 02*

   Very Light Sterile Neutrinos at NOvA and T2K

   André de Gouvêa🇺🇸 · Giancarlo Jusino Sánchez🇺🇸 · Kevin J. Kelly🇺🇸

   Over the last several years, our understanding of neutrino oscillations has developed significantly due to the long-baseline measurements of muon-neutrino disappearance and muon-to-electron-neutrino appearance at the T2K and NOvA experiments. However, when interpreted under the standard-three-massive-neutrinos paradigm, a tension has emerged between the two experiments' data. Here, we examine whether this tension can be alleviated when a fourth, very light neutrino is added to the picture. Specifically, we focus on the scenario in which this new neutrino has a mass similar to, or even lighter than, the three mostly-active neutrinos that have been identified to date. We find that, for some regions of parameter space, the four-neutrino framework is favored over the three-neutrino one with moderate (a little under two sigma) significance. Interpreting these results, we provide future outlook for near-term and long-term experiments if this four-neutrino framework is indeed true.

   hep-phhep-exPRD(2022)·23 citations
3. 03*

   Search for a lighter neutral custodial fiveplet scalar in the Georgi-Machacek model

   Chu Wang🇨🇳 · Jun-Quan Tao🇨🇳 · M. Aamir Shahzad🇨🇳 · Guo-Ming Chen🇨🇳 · S. Gascon-Shotkin🇫🇷

   Many researches from both the theoretical and experimental sides have been performed to search for a new Higgs Boson lighter than the 125 $GeV$ Higgs boson which was discovered at the LHC in 2012. In this paper we explore the possibility of constraining a lighter neutral custodial fiveplet scalar $H_5^0$ in the Georgi-Machacek (GM) model by the latest results of the search for a lighter Higgs boson decaying into two photons from LHC data. The custodial-singlet mass eigenstate $h$ or $H$ is considered to be the LHC observed 125 $GeV$ Higgs boson. A new set of constrained parameters that is favoured by low-mass $H_5^0$, is proposed to generate events efficiently. The production of $H_5^0$ from the scan based on the constrained parameters is compared to the latest results of the search for a lighter Higgs boson decaying into two photons by CMS Collaboration, after the theoretical constraints from GM model and the constraints from all existing relevant experimental measurements including the recent results of the Higgs boson searches from the LHC. The numerical analyses of the surviving GM parameter space are performed. The tendencies and correlations of the GM input parameters from the phenomenological studies are summarized. In addition the discovery potential of other interesting decay channels of this low-mass neutral custodial fiveplet scalar are discussed.

   hep-phCPC(2022)·19 citations
4. 04*

   Scotogenic Dirac neutrino mass models embedded with leptoquarks: one pathway to address the flavor anomalies and the neutrino masses together

   Shao-Ping Li🇨🇳 · Xin-Qiang Li🇨🇳 · Xin-Shuai Yan🇨🇳 · Ya-Dong Yang🇨🇳

   If the leptoquarks proposed to account for the intriguing anomalies observed in the $B$-meson decays, $R_{D^{(\ast )}}$ and $R_{K^{(\ast )}}$, as well as in the anomalous magnetic moment of the muon, $(g-2{)}_{\mu }$, can be embedded into the scotogenic Dirac neutrino model, all these flavor anomalies, together with the origin of neutrino masses and the nature of dark matter, would be potentially addressed in a unified picture. Among the minimal seesaw, one-loop, and two-loop realizations of the dimension-4 effective operator ${\mathcal{L}}_4$ for the Dirac neutrino masses, we show that plenty of diagrams associated with the two-loop realizations of ${\mathcal{L}}_4$ can support the coexistence of leptoquarks and dark matter candidates. After a simple match of these leptoquarks to those that can accommodate all the flavor anomalies, we establish the scotogenic Dirac neutrino models embedded with leptoquarks, which could address all the problems mentioned above.

   hep-phEPJC(2022)·17 citations
5. 05*

   Cumulants of the chiral order parameter at lower RHIC energies

   Christoph Herold🇹🇭 · Ayut Limphirat🇹🇭 · Poramin Saikham🇹🇭 · Marlene Nahrgang🇫🇷

   We study cumulants of the chiral order parameter as function of beam energy as a possible signal for the presence of a critical end point and first-order phase transition in the QCD phase diagram. We model the expansion of a heavy-ion collision by a fluid dynamic expansion coupled to the explicit propagation of the chiral order parameter sigma via a Langevin equation. We evolve the medium until a parametrized freeze-out condition is met where we calculate event-by-event fluctuations and cumulants of sigma which are expected to follow the trend of net-proton number cumulants. We emphasize the role of a nonequilibrium first-order phase transition: The presence of an unstable phase causes the well-known bending of the trajectories in the space of temperature and baryochemical potential. For these cases at lower beam energies, the system crosses the freeze-out line more than once, allowing us to calculate a range of cumulants for each initial condition which are overall enhanced for the second hit of the freeze-out line. We thus find not only the critical end point but also the phase transition of the underlying model clearly reflected in the cumulants. The impact of volume fluctuations is demonstrated to play a measurable role for fluid dynamical evolutions that last significantly long.

   hep-phnucl-thPhys.Scripta(2022)·1 citation
6. 06*

   Dispersive approach to HVP for muon g-2

   Zhiqing Zhang🇫🇷

   The dispersive approaches to the hadronic vacuum polarisation contributions to the muon anomalous magnetic moment $a_{\mu }$ are described. The main issues are discussed followed by perspectives in the next years.

   hep-phhep-ex0 citations
7. 07*

   Quantum number assignments of light strange baryons in Regge phenomenology

   Juhi Oudichhya🇮🇳 · Keval Gandhi🇮🇳 · Ajay Kumar Rai🇮🇳

   The present article contains the descriptive study of light strange baryons $\Lambda$, $\Sigma$, $\Xi$, and $\Omega$. The Regge phenomenology with quasi-linear Regge trajectories has been employed and the relations between Regge slopes, intercepts, and baryon masses have been extracted. With the aid of these relations, ground state masses are obtained for $\Xi$ and $\Omega$ baryons. Further, the Regge parameters have also been estimated to calculate the excited state masses for $\Lambda$, $\Sigma$, $\Xi$, and $\Omega$ baryons in both the $(J,M^2)$ and $(n,M^2)$ planes. The obtained results are compared with available experimental data and various theoretical approaches. The spin-parity of recently observed light baryons are predicted in this work and our predictions may be useful in future experimental searches of these baryons and their $J^P$ assignments.

   hep-phNPA(2023)·30 citations
8. 08*

   Heavy-Quark Diffusion in the Quark-Gluon Plasma

   Min He🇨🇳 · Hendrik van Hees🇩🇪 · Ralf Rapp🇺🇸

   The diffusion of heavy quarks through the quark-gluon plasma (QGP) as produced in high-energy heavy-ion collisions has long been recognized as an excellent probe of its transport properties. In addition, the experimentally observed heavy-flavor hadrons carry valuable information about the hadronization process of the transported quarks. Here we review recent progress in the theoretical developments of heavy-quark interactions in the QGP and how they relate to the nonperturbative hadronization process, and discuss the recent status of the pertinent phenomenology in heavy-ion collisions at the RHIC and the LHC. The interactions of heavy quarks in the QGP also constitute a central building block in the description of the heavy quarkonia which controls their transport parameters as well. We will thus focus on theoretical approaches that aim for a unified description of open and hidden heavy-flavor particles in medium, and discuss how they can be constrained by lattice QCD "data" and utilized to deduce fundamental properties of the microscopic interactions and emerging spectral properties of the strongly coupled QGP.

   hep-phnucl-thPPNP(2023)·110 citations
9. 09*

   W boson mass in Singlet-Triplet Scotogenic dark matter model

   Aditya Batra🇮🇳 · ShivaSankar K.A🇮🇳 · Sanjoy Mandal🇰🇷 · Rahul Srivastava🇮🇳

   The recent high precision measurement of $W$ boson mass by CDF-II collaboration points to the contribution(s) of new physics beyond the Standard Model. One of the minimalistic ways to account for the anomalous $W$ boson mass is by introducing a hyperchargeless real $SU(2{)}_L$ triplet scalar whose vacuum expectation value explicitly contributes to the $W$ boson mass at the tree level while the $Z$ boson mass remains the same. Such a triplet can be naturally embedded in a singlet-triplet scotogenic model for one loop neutrino mass generated by dark sector particles running in the loop. We discuss the detailed phenomenology of the model, obtaining the parameter space consistent with the CDF-II $W$ boson mass measurements. The dark matter as well as the constraints comings from $S$, $T$, $U$ parameters are also analyzed.

   hep-phhep-exInt.J.Mod.Phys.A(2023)·36 citations
10. 10*

    Theoretical study of the process $D_s^{+}\to {\pi }^{+}{K}_S^0{K}_S^0$ and the isovector partner of $f_0(1710)$

    Xin Zhu🇨🇳 · De-Min Li🇨🇳 · En Wang🇨🇳 · Li-Sheng Geng🇨🇳 · Ju-Jun Xie🇨🇳

    We present a theoretical study of $a_0(1710)$, the isovector partner of $f_0(1710)$, in the process $D_s^{+}\to {\pi }^{+}{K}_S^0{K}_S^0$. The weak interaction part proceeds through the charm quark decay process: $c(\bar{s})\to (s+\bar{d}+u)(\bar{s})$, while the hadronization part takes place in two mechanisms, differing in how the quarks from the weak decay combines into $\pi K^{\ast }$ with a quark-antiquark pair $q\bar{q}$ with the vacuum quantum numbers. In addition to the contribution from the tree diagram of the $K^{\ast +}\to {\pi }^{+}{K}_S^0$, we have also considered the $K^{\ast }{\bar{K}}^{\ast }$ final-state interactions within the chiral unitary approach to generate the intermediate state $a_0(1710)$, then it decays into the final states $K_S^0{K}_S^0$. We find that the recent experimental measurements on the $K_S^0{K}_S^0$ and ${\pi }^{+}{K}_S^0$ invariant mass distributions can be well reproduced, and the proposed mechanism can provide valuable information on the nature of scalar $f_0(1710)$ and its isovector partner $a_0(1710)$.

    hep-phPRD(2022)·33 citations
11. 11*

    Same-hemisphere three-gluon-emission contribution to the zero-jettiness soft function at N3LO QCD

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

    We complete the calculation of the three-gluon-emission contribution to the same-hemisphere part of the zero-jettiness soft function at next-to-next-to-next-to-leading order in perturbative QCD.

    hep-phPRD(2022)·25 citations
12. 12*

    Interpreting the $W$ mass anomaly in the vector-like quark models

    Junjie Cao🇨🇳 · Lei Meng🇨🇳 · Liangliang Shang🇨🇳 · Shiyu Wang🇨🇳 · Bingfang Yang🇨🇳

    The new measurement of $W$-boson mass by the CDF collaboration revealed a remarkable $7\sigma$ disagreement with the Standard Model (SM) prediction. If confirmed by other experiments, then the disagreement strongly indicates the existence of new physics beyond the SM. In this work, seven vectorlike quark (VLQ) extensions of the SM are investigated to interpret the anomaly, and it is found that three can explain the anomaly in broad parameter space. The explanations are consistent with the constraints from oblique parameters, the LHC search for VLQs, the measurements of the properties for the top quark, bottom quark, and Higgs boson, and the perturbativity criterion. The typical size of the involved Yukawa coupling is around 1, which is comparable to the top quark Yukawa coupling in the SM. The other extensions, however, either predict a negative correction to the mass in reasonable parameter space or explain the anomaly by unnatural theoretical input parameters.

    hep-phPRD(2022)·80 citations
13. 13*

    Study of $N(1520)$ and $N(1535)$ structures via ${\gamma }^{\ast }p\to N^{\ast }$ transitions

    A. Kaewsnod🇹🇭 · K. Xu🇹🇭 · Z. Zhao🇹🇭 · X. Y. Liu🇹🇭 · S. Srisuphaphon🇹🇭 · A. Limphirat🇹🇭 · Y. Yan🇹🇭

    The helicity amplitudes of the $N(1520)$ and $N(1535)$ resonances in the ${\gamma }^{\ast }p\to N^{\ast }$ electromagnetic transition are studied in the constituent quark model using the impulse approximation, with the proton and resonances assumed to be in three-quark configurations. The comparison of theoretical results and experimental data on the helicity amplitudes $A_{1/2}$, $A_{3/2}$, and $S_{1/2}$ indicates that the $N(1520)$ and $N(1535)$ resonances are primarily composed of three-quark $L=1$ states but may contain additional components. However, it is improbable that contributions from meson clouds will be dominant at low $Q^2$.

    hep-phnucl-thEPJA(2022)·4 citations
14. 14*

    Majorana neutrino mass constraints in the landscape of nuclear matrix elements

    Eligio Lisi🇮🇹 · Antonio Marrone🇮🇹

    We discuss up-to-date constraints on the Majorana neutrino mass $m_{\beta \beta }$ from neutrinoless double beta decay ($0\nu \beta \beta$) searches in experiments using different isotopes: KamLAND-Zen and EXO (${}^{136}$Xe), GERDA and MAJORANA (${}^{76}$Ge) and CUORE (${}^{130}$Te). Best fits and upper bounds on $m_{\beta \beta }$ are explored in the general landscape of nuclear matrix elements (NME), as well as for specific NME values obtained in representative nuclear models. By approximating the likelihood of $0\nu \beta \beta$ signals through quadratic forms, the analysis of separate and combined isotope data becomes exceedingly simple, and allows to clarify various aspects of multi-isotope data combinations. In particular, we analyze the relative impact of different data in setting upper bounds on $m_{\beta \beta }$, as well as the conditions leading to nonzero $m_{\beta \beta }$ at best fit, for variable values of the NMEs. Detailed results on $m_{\beta \beta }$ from various combinations of data are reported in graphical and numerical form. Implications for future $0\nu \beta \beta$ data analyses and NME calculations are briefly discussed.

    hep-phhep-exnucl-exnucl-thPRD(2022)·13 citations
15. 15*

    Implications of CDF $W$-mass and $(g-2{)}_{\mu }$ on $U(1{)}_{L_{\mu }-L_{\tau }}$ model

    Seungwon Baek🇰🇷

    We study the implications of the recent anomalies in the $W$-boson mass and the anomalous magnetic moment of the muon on $U(1{)}_{L_{\mu }-L_{\tau }}$ model. We show that the introduction of vector-like leptons which mix with muon can solve both anomalies. Contrary to the conventional wisdom the electroweak scale $Z^{\prime }$-boson is allowed without conflict with the trident neutrino production experiments.

    hep-ph41 citations
16. 16*

    Collective modes of gluons in an anisotropic thermo-magnetic medium

    Bithika Karmakar🇷🇸 · Ritesh Ghosh🇮🇳 · Arghya Mukherjee🇮🇳

    We study the collective modes of gluons in an anisotropic thermal medium in the presence of a constant background magnetic field using the hard-thermal loop (HTL) perturbation theory. The momentum space anisotropy of the medium has been incorporated through the generalized $‘$Romatschke-Strickland' form of the distribution function, whereas, the magnetic modification arising from the quark loop contribution has been taken into account in the lowest Landau level approximation. We consider two special cases: (i) a spheroidal anisotropy with the anisotropy vector orthogonal to the external magnetic field and (ii) an ellipsoidal anisotropy with two mutually orthogonal vectors describing aniostropies along and orthogonal to the field direction. The general structure of the polarization tensor in both cases are equivalent and consists of six independent basis tensors. We find that the introduction of momentum anisotropy ingrains azimuthal angular dependence in the thermo-magnetic collective modes. Our study suggests that the presence of a strong background magnetic field can significantly reduce the growth rate of the unstable modes which may have important implications in the equilibration of magnetized quark-gluon plasma.

    hep-phnucl-thPRD(2022)·9 citations
17. 17*

    Time-delayed neutrino emission from supernovae as a probe of dark matter-neutrino interactions

    Jose Alonso Carpio🇺🇸 · Ali Kheirandish🇺🇸 · Kohta Murase🇺🇸

    Thermal MeV neutrino emission from core-collapse supernovae offers a unique opportunity to probe physics beyond the Standard Model in the neutrino sector. The next generation of neutrino experiments, such as DUNE and Hyper-Kamiokande, can detect $\mathcal{O}(10^3)$ and $\mathcal{O}(10^4)$ neutrinos in the event of a Galactic supernova, respectively. As supernova neutrinos propagate to Earth, they may interact with the local dark matter via hidden mediators and may be delayed with respect to the initial neutrino signal. We show that for sub-MeV dark matter, the presence of dark matter-neutrino interactions may lead to neutrino echoes with significant time delays. The absence or presence of this feature in the light curve of MeV neutrinos from a supernova allows us to probe parameter space that has not been explored by dark matter direct detection experiments.

    hep-phastro-ph.HEJCAP(2023)·20 citations
18. 18*

    Singlet-Doublet Fermion Origin of Dark Matter, Neutrino Mass and W-Mass Anomaly

    Debasish Borah🇮🇳 · Satyabrata Mahapatra🇮🇳 · Narendra Sahu🇮🇳

    Motivated by the recently reported anomaly in W boson mass by the CDF collaboration with $7\sigma$ statistical significance, we consider a singlet-doublet (SD) Majorana fermion dark matter (DM) model where the required correction to W boson mass arises from radiative corrections induced by SD fermions. While a single generation of SD fermions, odd under an unbroken $Z_2$ symmetry, can not explain the W boson mass anomaly while being consistent with DM phenomenology, two generations of SD fermions can do so with the heavier generation playing the dominant role in W-mass correction and lighter generation playing the role in DM phenomenology. Additionally, such multiple generations of SD fermions can also generate light neutrino masses radiatively if a $Z_2$-odd singlet scalar is included.

    hep-phastro-ph.COhep-exPLB(2022)·59 citations
19. 19*

    Is the $\bar{\theta }$ parameter of QCD constant?

    Hooman Davoudiasl🇺🇸 · Julia Gehrlein🇺🇸 · Robert Szafron🇺🇸

    Testing the cosmological variation of fundamental constants of Nature can provide valuable insights into new physics scenarios. While many such constraints have been derived for Standard Model coupling constants and masses, the $\bar{\theta }$ parameter of QCD has not been as extensively examined. This letter discusses potentially promising paths to investigate the time dependence of the $\bar{\theta }$ parameter. While laboratory searches for CP-violating signals of $\bar{\theta }$ yield the most robust bounds on today's value of $\bar{\theta }$, we show that CP-conserving effects provide constraints on the variation of $\bar{\theta }$ over cosmological timescales. We find no evidence for a variation of $\bar{\theta }$ that could have implied an "iron-deficient" Universe at higher redshifts. By converting recent atomic clock constraints on a variation of constants, we infer $d({\bar{\theta }}^2)/dt\le 6\times 10^{-15}{\text{yr}}^{-1}$, at 1-$\sigma$. Finally, we also sketch an axion model that results in a varying $\bar{\theta }$ and could lead to excess diffuse gamma ray background, from decays of axions produced in high redshift supernova explosions.

    hep-phastro-ph.COPRL(2022)·4 citations
20. 20*

    Ultra-high-energy cosmic ray acceleration by magnetic reconnection in relativistic jets and the origin of very high energy emission

    E. De Gouveia Dal Pino🇨🇺 · T.E. Medina-Torrejon · L.H.S. Kadowaki · G. Kowal · J.C. Rodriguez-Ramirez

    Relativistic jets are believed to be born magnetically dominated. Very and ultra-high energy cosmic rays can be efficiently accelerated by magnetic reconnection in these sources. We here demonstrate this directly, with no extrapolations to large scales, by means of three-dimensional relativistic magnetohydrodynamical (3D-RMHD) simulations of a Poyinting flux dominated jet. We inject thousands of low-energy protons in the region of a relativistic jet that corresponds to the transition from magnetically to kinetically dominated, where its magnetization parameter is $\sigma \sim 1$. In this region, there is efficient fast magnetic reconnection which is naturally driven by current-driven-kink instability (CDKI) turbulence in the helical magnetic fields of the jet. We find that the particles are accelerated by Fermi process in the reconnection regions (and by drift in the final stages) up to energies $E\sim 10^{18}$ eV for background magnetic fields $B\sim 0.1$ G, and $E\sim 10^{20}$ eV for $B\sim 10$ G. We have also derived from the simulations the acceleration rate due to magnetic reconnection which has a weak dependence on the particles energy $r_{acc}\propto E^{-0.1}$, characteristic of exponential growth. The energy spectrum of the accelerated particles develops a power-law tail with spectral index $p\sim -1.2$. This hardness of the spectrum must decrease when particle losses and feedback into the background plasma are included. Our results can explain observed flux variability in the emission of blazars at the very high energy band as well as the associated neutrino emission. Successful applications of our results to the blazars MRK 421 and TXS 0506+056 are also discussed.

    ↳ astro-ph.HEhep-phPoS(2021)·3 citations
21. 21*

    Thermal Friction as a Solution to the Hubble and Large-Scale Structure Tensions

    Kim V. Berghaus🇺🇸 · Tanvi Karwal🇺🇸

    Thermal friction offers a promising solution to the Hubble and the large-scale structure (LSS) tensions. This additional friction acts on a scalar field in the early universe and extracts its energy density into dark radiation, the cumulative effect being similar to that of an early dark energy (EDE) scenario. The dark radiation automatically redshifts at the minimal necessary rate to improve the Hubble tension. On the other hand, the addition of extra radiation to the Universe can improve the LSS tension. We explore this model in light of cosmic microwave background (CMB), baryon acoustic oscillation and supernova data, including the SH0ES $H_0$ measurement and the Dark Energy Survey Y1 data release in our analysis. Our results indicate a preference for the regime where the scalar field converts to dark radiation at very high redshifts, asymptoting effectively to an extra self-interacting radiation species rather than an EDE-like injection. In this limit, thermal friction can ease both the Hubble and the LSS tensions, but not resolve them. We find the source of this preference to be the incompatibility of the CMB data with the linear density perturbations of the dark radiation when injected at redshifts close to matter-radiation equality.

    ↳ astro-ph.COhep-phPRD(2023)·40 citations
22. 22*

    Superradiant instabilities by accretion disks in scalar-tensor theories

    Giuseppe Lingetti🇮🇹 · Enrico Cannizzaro🇮🇹 · Paolo Pani🇮🇹

    We study the superradiant instability in scalar-tensor theories of gravitation, where matter outside a black hole provides an effective mass to the scalar degree of freedom of the gravitational sector. We discuss this effect for arbitrarily spinning black holes and for realistic models of truncated thin and thick accretion disks (where the perturbation equations are nonseparable), paying particular attention to the role of hot coronal flows in the vicinity of the black hole. The system qualitatively resembles the phenomenology of plasma-driven superradiant instabilities in General Relativity. Nevertheless, we show that the obstacles hampering the efficiency of plasma-driven superradiant instabilities in General Relativity can be circumvented in scalar-tensor theories. We find a wide range of parameter space where superradiant instabilities can be triggered in realistic scenarios, and discuss the constraints on scalar-tensor theories imposed by this effect. In particular, we argue that the existence of highly spinning accreting black holes is in tension with some scalar-tensor alternatives to the dark energy, e.g. symmetron models with screening.

    ↳ gr-qcastro-ph.HEhep-phPRD(2022)·17 citations
23. 23*

    Color-Kinematics Duality for Sudakov Form Factor in Non-Supersymmetric Pure Yang-Mills Theory

    Zeyu Li🇨🇳 · Gang Yang🇨🇳 · Jinxuan Zhang🇨🇳

    We study the duality between color and kinematics for the Sudakov form factors of $\mathrm{tr}(F^2)$ in non-supersymmetric pure Yang-Mills theory. We construct the integrands that manifest the color-kinematics duality up to two loops. The resulting numerators are given in terms of Lorentz products of momenta and polarization vectors, which have the same powers of loop momenta as that from the Feynman rules. The integrands are checked by $d$-dimensional unitarity cuts and are valid in any dimension. We find that massless-bubble and tadpole topologies are needed at two loops to realize the color-kinematics duality. Interestingly, the two-loop solution contains a large number of free parameters suggesting the duality may hold at higher loop orders.

    ↳ hep-thhep-phCommun.Theor.Phys.(2022)·11 citations
24. 24*

    Optical Atomic Clock aboard an Earth-orbiting Space Station (OACESS): Enhancing searches for physics beyond the standard model in space

    Vladimir Schkolnik🇩🇪 · Dmitry Budker🇩🇪 · Oliver Fartmann🇩🇪 · Victor Flambaum🇦🇺 · Leo Hollberg🇺🇸 · Tigran Kalaydzhyan🇺🇸 · Shimon Kolkowitz🇺🇸 · Markus Krutzik🇩🇪 · Andrew Ludlow🇺🇸 · Nathan Newbury🇺🇸 · Christoph Pyrlik🇩🇪 · Laura Sinclair🇩🇪 and 4 other authors

    We present a concept for a high-precision optical atomic clock (OAC) operating on an Earth-orbiting space station. This pathfinder science mission will compare the space-based OAC with one or more ultra-stable terrestrial OACs to search for space-time-dependent signatures of dark scalar fields that manifest as anomalies in the relative frequencies of station-based and ground-based clocks. This opens the possibility of probing models of new physics that are inaccessible to purely ground-based OAC experiments where a dark scalar field may potentially be strongly screened near Earth's surface. This unique enhancement of sensitivity to potential dark matter candidates harnesses the potential of space-based OACs.

    ↳ physics.atom-phgr-qchep-phphysics.space-phQuantum Sci.Technol.(2023)·25 citations
25. 25*

    Formation and Abundance of Late Forming Primordial Black Holes as Dark Matter

    Amlan Chakraborty🇮🇳 · Prolay K Chanda🇺🇸 · Kanhaiya Lal Pandey🇮🇳 · Subinoy Das🇮🇳

    We propose a novel mechanism where Primordial Black Hole (PBH) dark matter is formed much later in the history of the universe between the epoch of Big Bang Nucleosynthesis (BBN) and Cosmic Microwave Background (CMB) photon decoupling. In our setup, one does not need to modify the scale-invariant inflationary power spectra; instead, a late phase transition in strongly interacting fermion-scalar fluid (which naturally occurs around red-shift $10^6\le z_T\le 10^8$ ) creates an instability in the density perturbation as sound speed turns imaginary. As a result, the dark matter perturbation grows exponentially in sub-Compton scales. This follows the immediate formation of early dense dark matter halo, which finally evolves into PBH due to cooling through scalar radiation. We calculate the variance of the density perturbations and PBH fractional abundances $f(M)$ by using a non-monochromatic mass function. We find the peak of our PBH mass function lies between $10^{-16}-10^{-14}$ solar mass for $z_T\simeq 10^6$, and thus it can be the entire dark matter of the universe. In PBH formation, one would expect a temporary phase where an attractive scalar balances the Fermi pressure. We numerically confirm that such a state indeed exists, and we find the radius and density profile of the temporary static structure of the dark matter halo, which finally evolves to PBH due to cooling through scalar radiation.

    ↳ astro-ph.COgr-qchep-phhep-thApJ·46 citations
26. 26*

    Gravitational Waves from Cosmological Phase Transitions

    Moritz Breitbach🇩🇪

    In the present thesis, the author reviews the physics of cosmological first-order phase transitions that may have occured shortly after the Big Bang. Such transitions proceed via the nucleation and expansion of true vacuum bubbles and give rise to a rich phenomenology, for instance the emission of a stochastic gravitational-wave background caused by bubble collisions. The author discusses, in depth, the formalism of the effective scalar potential and its different contributions in the loop expansion, points out the necessary ingredients for a first-order transition, and assesses the detectability of the associated gravitational-wave spectrum via future space-based observatories and pulsar timing arrays. He then applies the the developed phenomenological toolbox to investigate the detection prospect for phase transitions in the context of specific theories such as the Vev Flip-Flop (a dark matter mechanism) and the Dark Photon Model.

    ↳ astro-ph.COhep-ph7 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.