Thu·Aug 27, 2020Thursday·August 27, 2020

1. 01*

   Synergies and Prospects for Early Resolution of the Neutrino Mass Ordering

   Anatael Cabrera🇫🇷 · Yang Han🇫🇷 · Michel Obolensky🇫🇷 · Fabien Cavalier🇫🇷 · João Coelho🇫🇷 · Diana Navas Nicolás🇫🇷 · Hiroshi Nunokawa🇧🇷 · Laurent Simard🇫🇷 · Jianming Bian🇺🇸 · Nitish Nayak🇺🇸 · Juan Pedro Ochoa-Ricoux🇺🇸 · Bedřich Roskovec🇨🇿 and 14 other authors

   The measurement of neutrino Mass Ordering (MO) is a fundamental element for the understanding of leptonic flavour sector of the Standard Model of Particle Physics. Its determination relies on the precise measurement of $\Delta m_{31}^2$ and $\Delta m_{32}^2$ using either neutrino vacuum oscillations, such as the ones studied by medium baseline reactor experiments, or matter effect modified oscillations such as those manifesting in long-baseline neutrino beams (LB$\nu$B) or atmospheric neutrino experiments. Despite existing MO indication today, a fully resolved MO measurement ($\ge$5$\sigma$) is most likely to await for the next generation of neutrino experiments: JUNO, whose stand-alone sensitivity is $\sim$3$\sigma$, or LB$\nu$B experiments (DUNE and Hyper-Kamiokande). Upcoming atmospheric neutrino experiments are also expected to provide precious information. In this work, we study the possible context for the earliest full MO resolution. A firm resolution is possible even before 2028, exploiting mainly vacuum oscillation, upon the combination of JUNO and the current generation of LB$\nu$B experiments (NOvA and T2K). This opportunity is possible thanks to a powerful synergy boosting the overall sensitivity where the sub-percent precision of $\Delta m_{32}^2$ by LB$\nu$B experiments is found to be the leading order term for the MO earliest discovery. We also found that the comparison between matter and vacuum driven oscillation results enables unique discovery potential for physics beyond the Standard Model.

   hep-phhep-exSci.Rep.(2022)·33 citations
2. 02*

   Can a protophobic vector boson explain the ATOMKI anomaly?

   Xilin Zhang🇺🇸 · Gerald A. Miller🇺🇸

   In 2016, the ATOMKI collaboration announced [PRL {\bf 116}, 042501 (2016)] observing an unexpected enhancement of the $e^{+}-e^{-}$ pair production signal in one of the ${}^8$Be nuclear transitions induced by an incident proton beam on a ${}^7$Li target. Many beyond-standard-model physics explanations have subsequently been proposed. One popular theory is that the anomaly is caused by the creation of a protophobic vector boson ($X$) with a mass around 17 MeV [e.g., PRL\ {\bf 117}, 071803 (2016)] in the nuclear transition. We study this hypothesis by deriving an isospin relation between photon and $X$ couplings to nucleons. This allows us to find simple relations between protophobic $X$-production cross sections and those for measured photon production. The net result is that $X$ production is dominated by direct transitions induced by $E{1}^X$ and $L{1}^X$ (transverse and longitudinal electric dipoles) and $C{1}^X$ (charge dipole) without going through any nuclear resonance (i.e. Bremsstrahlung radiation) with a smooth energy dependence that occurs for all proton beam energies above threshold. This contradicts the experimental observations and invalidates the protophobic vector boson explanation.

   hep-phhep-exnucl-exnucl-thPLB(2021)·46 citations
3. 03*

   Theoretical study of the $D^0\to K^{-}{\pi }^{+}\eta$ reaction

   Genaro Toledo🇲🇽 · Natsumi Ikeno🇯🇵 · Eulogio Oset🇪🇸

   We develop a model to study the $D^0\to K^{-}{\pi }^{+}\eta$ weak decay, starting with the color favored external emission and Cabibbo favored mode at the quark level. A less favored internal emission decay mode is also studied as a source of small corrections. Some pairs of quarks are allowed to hadronize producing two pseudoscalar mesons, which posteriorly are allowed to interact to finally provide the $K^{-}{\pi }^{+}\eta$ state. The chiral unitary approach is used to take into account the final state interaction of pairs of mesons, which has as a consequence the production of the $\kappa$ ($K_0^{\ast }(700)$) and the $a_0(980)$ resonances, very well visible in the invariant mass distributions. We also introduce the ${\bar{K}}^{\ast 0}\eta$ production in a phenomenological way and show that the $s$-wave pseudoscalar interaction together with this vector excitation mode are sufficient to provide a fair reproduction of the experimental data. The agreement with the data, in particular the relative weight of the $a_0(980)$ to the $\kappa$ excitation, provides extra support to the picture used, in which these two resonances are a consequence of the interaction of pseudoscalar mesons and not ordinary $q\bar{q}$ mesons.

   hep-phEPJC(2021)·32 citations
4. 04*

   Reduction for one-loop tensor Feynman integrals in the relativistic quantum field theories at finite temperature and/or finite density

   Hao-Ran Chang🇨🇳

   The \emph{conventional} Passarino-Veltman reduction is a systematic procedure based on the Lorentz covariance, which can efficiently reduce the one-loop tensor Feynman integrals in the relativistic quantum field theories (QFTs) at zero temperature and zero density. However, the Lorentz covariance is explicitly broken when either of the temperature and density is finite, due to a rest reference frame of the many-body system in which the temperature and density are measured, rendering the \emph{conventional} Passarino-Veltman reduction not applicable anymore to reduce the one-loop tensor Feynman integrals therein. In this paper, we report a \emph{generalized} Passarino-Veltman reduction which can efficiently simplify the one-loop tensor Feynman integrals in the relativistic QFTs at finite temperature and/or finite density. The \emph{generalized} Passarino-Veltman reduction can analyze the one-loop tensor Feynman integrals in a wide range of physical systems described by the relativistic QFTs at finite temperature and/or finite density, such as quark-gluon plasma in nuclear physics.

   hep-phcond-mat.mes-hallcond-mat.str-elnucl-thPRD(2024)·2 citations
5. 05*

   Decay widthes of ${}^3{P}_J$ charmonium to $DD,D{D}^{\ast },D^{\ast }{D}^{\ast }$ and corresponding mass shifts of ${}^3{P}_J$ charmonium

   Hui-Yun Cao🇨🇳 · Hai-Qing Zhou🇨🇳

   In this work, we calculate the amplitudes of the processes $c\bar{c}({}^3{P}_J)\to DD,D{D}^{\ast },D^{\ast }{D}^{\ast }\to c\bar{c}({}^3{P}_J)$ in the leading order of the nonrelativistic expansion. The imaginary parts of the amplitudes are corresponding to the branch decay widthes of the charmonium $c\bar{c}({}^3{P}_J)\to DD,D{D}^{\ast },D^{\ast }{D}^{\ast }$ and the real parts are corresponding to the mass shifts of the charmonium $c\bar{c}({}^3{P}_J)$ due to these decay channels. After absorbing the polynomial contributions which are pure real and include the UV divergences, the ratios between the branch decay widthes and the corresponding mass shifts are only dependent on the center-of-mass energy. We find the decay widthes and the mass shifts of the ${}^3{P}_2$ states are exact zero in the leading order. The ratios between the branch decay widthes and the mass shifts for the ${}^3{P}_0,{}^3{P}_1$ states are larger than 5 when the center-of-mass energy is above the $DD,D{D}^{\ast },D^{\ast }{D}^{\ast }$ threshold. The dependence of the mass shifts on the center-of-mass energy is nontrivial especially when the center-of-mass energy is below the threshold. The analytic results can be extended to the $b$ quark sector directly.

   hep-phhep-exEPJC(2020)·2 citations
6. 06*

   Parity and CP operations for Majorana neutrinos

   Kazuo Fujikawa🇯🇵

   The parity transformation law of the fermion field $\psi (x)$ is usually defined by the "${\gamma }^0$-parity" ${\psi }^p(t,-\vec{x})={\gamma }^0\psi (t,-\vec{x})$ with eigenvalues $\pm 1$, while the "$i{\gamma }^0$-parity" ${\psi }^p(t,-\vec{x})=i{\gamma }^0\psi (t,-\vec{x})$ is required for the Majorana fermion. The compatibility issues of these two parity laws arise in generic fermion number violating theories where a general class of Majorana fermions appear. In the case of Majorana neutrinos constructed from chiral neutrinos in an extension of the Standard Model, the Majorana neutrinos can be characterized by CP symmetry although C and P are separately broken. It is then shown that either choice of the parity operation, ${\gamma }^0$ or $i{\gamma }^0$, in the level of the starting fermions gives rise to the consistent and physically equivalent descriptions of emergent Majorana neutrinos both for Weinberg's model of neutrinos and for a general class of seesaw models. The mechanism of this equivalence is that the Majorana neutrino constructed from a chiral neutrino, which satisfies the classical Majorana condition $\psi (x)=C{\overline{\psi (x)}}^T$, allows the phase freedom $\psi (x)=e^{i\alpha }{\nu }_L(x)+e^{-i\alpha }C{\overline{{\nu }_L(x)}}^T$ with $\alpha =0\mathrm{or}\pi /4$ that accounts for the phase coming from the different definitions of parity for ${\nu }_L(x)$ and ensures the consistent definitions of CP symmetry $(\mathcal{C}\mathcal{P})\psi (x)(\mathcal{C}\mathcal{P}{)}^{†}=\pm i{\gamma }^0\psi (t,-\vec{x})$.

   hep-phhep-thPRD(2020)·5 citations
7. 07*

   Confronting Dual Models of the Strong Interaction

   I. Ridkokasha🇺🇦

   Studies of the mathematical properties of Regge-pole and dual amplitudes are important both for their applications in high energy phenomenology and in their generalizations to strings, superstrings, branes, and other theoretical developments. In the present paper, we investigate the similarities and differences between two classes of dual amplitudes: one with Mandelstam analyticity (DAMA) and another one with logarithmic trajectories (Dual-log). By using quantum (q-) deformations, new features of Dual-log amplitude are unveiled, in particular those concerning its asymptotic behavior and the spectrum of resonances. The two classes of dual amplitudes are compared in various kinematic regions: at fixed transferred momenta asymptotic, fixed angle asymptotic, and in the resonance region.

   hep-phMod.Phys.Lett.A(2021)·7 citations
8. 08*

   Inflation with a class of concave inflaton potentials in Randall-Sundrum model

   Ngo Phuc Duc Loc🇻🇳

   We investigate inflation with a class of concave inflaton potentials of the form $\sim {\varphi }^n$ $(0<n<1)$ in the Randall-Sundrum model with an infinite extra spatial dimension. We show that this class of models is much more in good agreement with observations compared to the standard inflation. We also find the range of the five-dimensional Planck scale ($M_5$) and show that large tensor-to-scalar ratios do not eliminate small-field inflation in braneworld cosmology.

   hep-phEPJC(2020)·7 citations
9. 09*

   Effective Operator Bases for Beyond Standard Model Scenarios: An EFT compendium for discoveries

   Upalaparna Banerjee🇮🇳 · Joydeep Chakrabortty🇮🇳 · Suraj Prakash🇮🇳 · Shakeel Ur Rahaman🇮🇳 · Michael Spannowsky🇬🇧

   It is not only conceivable but likely that the spectrum of physics beyond the Standard Model (SM) is non-degenerate. The lightest non-SM particle may reside close enough to the electroweak scale that it can be kinematically probed at high-energy experiments and on account of this, it must be included as an infrared (IR) degree of freedom (DOF) along with the SM ones. The rest of the non-SM particles are heavy enough to be directly experimentally inaccessible and can be integrated out. Now, to capture the effects of the complete theory, one must take into account the higher dimensional operators constituted of the SM DOFs and the minimal extension. This construction, BSMEFT, is in the same spirit as SMEFT but now with extra IR DOFs. Constructing a BSMEFT is in general the first step after establishing experimental evidence for a new particle. We have investigated three different scenarios where the SM is extended by additional (i) uncolored, (ii) colored particles, and (iii) abelian gauge symmetries. For each such scenario, we have included the most-anticipated and phenomenologically motivated models to demonstrate the concept of BSMEFT. In this paper, we have provided the full EFT Lagrangian for each such model up to mass dimension 6. We have also identified the $CP$, baryon ($B$), and lepton ($L$) number violating effective operators.

   hep-phhep-exhep-thJHEP(2021)·34 citations
10. 10*

    Investigation of the Lightest Hybrid Meson Candidate with a Coupled-Channel Analysis of $\bar{p}p$-, ${\pi }^{-}p$- and $\pi \pi$-Data

    B. Kopf🇩🇪 · M. Albrecht🇩🇪 · H. Koch🇩🇪 · M. Küßner🇩🇪 · J. Pychy🇩🇪 · X. Qin🇩🇪 · U. Wiedner🇩🇪

    A sophisticated coupled-channel analysis is presented that combines different processes: the channels ${\pi }^0{\pi }^0\eta$, ${\pi }^0\eta \eta$ and $K^{+}{K}^{-}{\pi }^0$ from $\bar{p}p$ annihilations, the P- and D-wave amplitudes of the $\pi \eta$ and $\pi {\eta }^{\prime }$ systems produced in ${\pi }^{-}p$ scattering, and data from $\pi \pi$-scattering reactions. Hence our analysis combines the data sets used in two independent previous analyses published by the Crystal Barrel experiment and by the JPAC group. Based on the new insights from these studies, this paper aims at a better understanding of the spin-exotic ${\pi }_1$ resonances in the light-meson sector. By utilizing the K-matrix approach and realizing the analyticity via Chew-Mandelstam functions the amplitude of the spin-exotic wave can be well described by a single ${\pi }_1$ pole for both systems, $\pi \eta$ and $\pi {\eta }^{\prime }$. The mass and width of the ${\pi }_1$-pole are measured to be $(1623\pm 47{}_{-75}^{+24}){MeV/c}^2$ and $(455\pm 88{}_{-175}^{+144})\mathrm{MeV}$.

    hep-phhep-exEPJC(2021)·55 citations
11. 11*

    $gg\to HH$: Combined Uncertainties

    J. Baglio🇨🇭 · F.Campanario🇪🇸 · S. Glaus🇩🇪 · M. Mühlleitner🇩🇪 · J. Ronca🇪🇸 · M. Spira🇨🇭

    In this note we discuss the combination of the usual renormalization and factorization scale uncertainties of Higgs-pair production via gluon fusion with the novel uncertainties originating from the scheme and scale choice of the virtual top mass. Moreover, we address the uncertainties related to the top-mass definition for different values of the trilinear Higgs coupling and their combination with the other uncertainties.

    hep-phhep-exPRD(2021)·205 citations
12. 12*

    The analytic leading color contribution to the Higgs-gluon form factor in QCD at NNLO

    Mario Prausa🇩🇪 · Johann Usovitsch🇩🇪

    We present an analytic three-loop result for the leading color contribution to the Higgs-gluon form factor in QCD. The leading color contribution is given at next-to-next-to-leading order by the $N_c^2$-term in QCD with $N_c$ colors. The main focus of this article lies on the evaluation of the relevant Feynman integrals with a special emphasis on the elliptic sector.

    hep-phJHEP(2021)·11 citations
13. 13*

    Projected NA62 sensitivity to heavy neutral lepton production in $K^{+}\to {\pi }^0{e}^{+}N$ decays

    Jean-Loup Tastet (1)🇩🇰 · Evgueni Goudzovski (2)🇬🇧 · Inar Timiryasov (3)🇨🇭 · Oleg Ruchayskiy (1) ((1) Niels Bohr Institute, (2) University of Birmingham, (3) EPFL)🇩🇰

    Heavy neutral leptons (HNLs) appear in many extensions of the Standard Model of particle physics. In this study, we investigate to which extent the NA62 experiment at CERN could improve the existing bounds on the HNL mixing angle $|U_e{|}^2$ by performing a missing mass search in $K^{+}\to {\pi }^0{e}^{+}N$ decays in flight. We show that the limit $|U_e{|}^2\simeq 2\times 10^{-6}$ can be reached with the currently available data in the mass range 125 -- 144 MeV, which is currently not well covered by production searches. Future data, together with a dedicated trigger and/or improvements in rejection of out-of-acceptance photons, can improve this limit by another order of magnitude.

    hep-phhep-exPRD(2021)·17 citations
14. 14*

    Einstein-Cartan Portal to Dark Matter

    Mikhail Shaposhnikov🇨🇭 · Andrey Shkerin🇨🇭 · Inar Timiryasov🇨🇭 · Sebastian Zell🇨🇭

    It is well-known since the works of Utiyama and Kibble that the gravitational force can be obtained by gauging the Poincaré group, which puts gravity on the same footing as the Standard Model fields. The resulting theory -- Einstein-Cartan gravity -- inevitably contains four-fermion and scalar-fermion interactions that originate from torsion associated with spin degrees of freedom. We show that these interactions lead to a novel mechanism for producing singlet fermions in the Early Universe. These fermions can play the role of dark matter particles. The mechanism is operative in a large range of dark matter particle masses: from a few keV up to $\sim 10^8$GeV. We discuss potential observational consequences of keV-scale dark matter produced this way, in particular for right-handed neutrinos. We conclude that a determination of the primordial dark matter momentum distribution might be able to shed light on the gravity-induced fermionic interactions.

    hep-phastro-ph.COgr-qchep-thPRL(2021)·67 citations
15. 15*

    Synchrotron-Like Radiation Beyond The Standard Model I: Hunting for new physics with the Sokolov-Ternov effect

    Iftah Galon🇺🇸

    Electron and positron beams in storage-rings self-polarize by emitting spin-flipping synchrotron radiation. If new ultralight particles couple to $e^{\pm }$, their emission in synchrotron-like radiation would modify the characteristic self-polarization time. We calculate the rate of spin-flipping synchrotron-like radiation in several simplified models, and find that the largest contribution is for an axial-vector. We use polarization time measurements from the Swiss-Light-Source, and SPEAR3 to set new strong limits on ultralight axial-vectors coupled to $e^{\pm }$.

    hep-phphysics.acc-ph1 citation
16. 16*

    Bounds on axion-like particles from the diffuse supernova flux

    Francesca Calore🇫🇷 · Pierluca Carenza🇮🇹 · Maurizio Giannotti🇺🇸 · Joerg Jaeckel🇩🇪 · Alessandro Mirizzi🇮🇹

    The cumulative emission of Axion-Like Particles (ALPs) from all past core-collapse supernovae (SNe) would lead to a diffuse flux with energies $\mathcal{O}(50)$ MeV. We use this to constrain ALPs featuring couplings to photons and to nucleons. ALPs coupled only to photons are produced in the SN core via the Primakoff process, and then converted into gamma rays in the Galactic magnetic field. We set a bound on $g_{a\gamma }\lesssim 5\times 10^{-10}{\mathrm{GeV}}^{-1}$ for $m_a\lesssim 10^{-11}\mathrm{eV}$, using recent measurements of the diffuse gamma-ray flux observed by the Fermi-LAT telescope. However, if ALPs couple also with nucleons, their production rate in SN can be considerably enhanced due to the ALPs nucleon-nucleon bremsstrahlung process. Assuming the largest ALP-nucleon coupling phenomenologically allowed, bounds on the diffuse gamma-ray flux lead to a much stronger $g_{a\gamma }\lesssim 6\times 10^{-13}{\mathrm{GeV}}^{-1}$ for the same mass range. If ALPs are heavier than $\sim$ keV, the decay into photons becomes significant, leading again to a diffuse gamma-ray flux. In the case of only photon coupling, we find, e.g. $g_{a\gamma }\lesssim 5\times 10^{-11}{\mathrm{GeV}}^{-1}$ for $m_a\sim 5\mathrm{keV}$. Allowing for a (maximal) coupling to nucleons, the limit improves to the level of $g_{a\gamma }\lesssim 10^{-19}{\mathrm{GeV}}^{-1}$ for $m_a\sim 20\mathrm{MeV}$, which represents the strongest constraint to date.

    hep-phastro-ph.HEPRD(2020)·107 citations
17. 17*

    Automated one-loop computations in the SMEFT

    Céline Degrande🇧🇪 · Gauthier Durieux🇮🇱 · Fabio Maltoni🇧🇪 · Ken Mimasu🇧🇪 · Eleni Vryonidou🇨🇭 · Cen Zhang🇨🇳

    We present the automation of one-loop computations in the standard-model effective field theory at dimension six. Our general implementation, dubbed SMEFT@NLO, covers all types of operators: bosonic, two- and four-fermion ones. Included ultraviolet and rational counterterms presently allow for fully differential predictions, possibly matched to parton shower, up to the one-loop level in the strong coupling or in four-quark operator coefficients. Exact flavor symmetries are imposed among light quark generations and an initial focus is set on top-quark interactions in the fermionic sector. We illustrate the potential of this implementation with novel loop-induced and next-to-leading-order computations relevant for top-quark, electroweak, and Higgs-boson phenomenology at the LHC and future colliders.

    hep-phhep-exPRD(2021)·275 citations
18. 18*

    Inverse catalysis effect of quark anomalous magnetic moment to chiral restoration and deconfinement phase transitions

    Jie Mei🇨🇳 · Shijun Mao🇨🇳

    The effect of quark anomalous magnetic moment (AMM) to chiral restoration and deconfinement phase transitions under magnetic fields is investigated in a Pauli-Villars regularized PNJL model. A linear-in-$B$ term for quark anomalous magnetic moment is introduced to the Lagrangian density of our model, and it plays the role of inverse catalysis to the phase transitions. With fixed magnetic field, the critical temperature decreases with quark AMM. When fixing quark AMM, the critical temperature increases with magnetic field for a small quark AMM, but decreases with magnetic field for a large quark AMM. The critical temperature of chiral restoration and deconfinement phase transitions is determined by the two competing factors, the catalysis effect of magnetic field and inverse catalysis of quark anomalous magnetic moment.

    hep-phnucl-thPRD(2020)·48 citations
19. 19*

    Cosmology Intertwined I: Perspectives for the Next Decade

    Eleonora Di Valentino🇬🇧 · Luis A. Anchordoqui🇺🇸 · Ozgur Akarsu🇹🇷 · Yacine Ali-Haimoud🇺🇸 · Luca Amendola🇩🇪 · Nikki Arendse🇩🇰 · Marika Asgari🇬🇧 · Mario Ballardini🇮🇹 · Spyros Basilakos🇬🇷 · Elia Battistelli🇮🇹 · Micol Benetti🇮🇹 · Simon Birrer🇺🇸 and 80 other authors

    The standard $\Lambda$ Cold Dark Matter cosmological model provides an amazing description of a wide range of astrophysical and astronomical data. However, there are a few big open questions, that make the standard model look like a first-order approximation to a more realistic scenario that still needs to be fully understood. In this Letter of Interest we will list a few important goals that need to be addressed in the next decade, also taking into account the current discordances present between the different cosmological probes, as the Hubble constant $H_0$ value, the ${\sigma }_8-S_8$ tension, and the anomalies present in the Planck results. Finally, we will give an overview of upgraded experiments and next-generation space-missions and facilities on Earth, that will be of crucial importance to address all these questions.

    ↳ astro-ph.COhep-phAstropart.Phys.(2021)·117 citations
20. 20*

    Cosmology Intertwined II: The Hubble Constant Tension

    Eleonora Di Valentino🇬🇧 · Luis A. Anchordoqui🇺🇸 · Ozgur Akarsu🇹🇷 · Yacine Ali-Haimoud🇺🇸 · Luca Amendola🇩🇪 · Nikki Arendse🇩🇰 · Marika Asgari🇬🇧 · Mario Ballardini🇮🇹 · Spyros Basilakos🇬🇷 · Elia Battistelli🇮🇹 · Micol Benetti🇮🇹 · Simon Birrer🇺🇸 and 81 other authors

    The current cosmological probes have provided a fantastic confirmation of the standard $\Lambda$ Cold Dark Matter cosmological model, that has been constrained with unprecedented accuracy. However, with the increase of the experimental sensitivity a few statistically significant tensions between different independent cosmological datasets emerged. While these tensions can be in portion the result of systematic errors, the persistence after several years of accurate analysis strongly hints at cracks in the standard cosmological scenario and the need for new physics. In this Letter of Interest we will focus on the $4.4\sigma$ tension between the Planck estimate of the Hubble constant $H_0$ and the SH0ES collaboration measurements. After showing the $H_0$ evaluations made from different teams using different methods and geometric calibrations, we will list a few interesting new physics models that could solve this tension and discuss how the next decade experiments will be crucial.

    ↳ astro-ph.COhep-phAstropart.Phys.(2021)·742 citations
21. 21*

    Cosmology Intertwined III: $f{\sigma }_8$ and $S_8$

    Eleonora Di Valentino🇬🇧 · Luis A. Anchordoqui🇺🇸 · Ozgur Akarsu🇹🇷 · Yacine Ali-Haimoud🇺🇸 · Luca Amendola🇩🇪 · Nikki Arendse🇩🇰 · Marika Asgari🇬🇧 · Mario Ballardini🇮🇹 · Spyros Basilakos🇬🇷 · Elia Battistelli🇮🇹 · Micol Benetti🇮🇹 · Simon Birrer🇺🇸 and 80 other authors

    The standard $\Lambda$ Cold Dark Matter cosmological model provides a wonderful fit to current cosmological data, but a few tensions and anomalies became statistically significant with the latest data analyses. While these anomalies could be due to the presence of systematic errors in the experiments, they could also indicate the need for new physics beyond the standard model. In this Letter of Interest we focus on the tension of the Planck data with weak lensing measurements and redshift surveys, about the value of the matter energy density ${\Omega }_m$, and the amplitude or rate of the growth of structure (${\sigma }_8,f{\sigma }_8$). We list a few interesting models for solving this tension, and we discuss the importance of trying to fit with a single model a full array of data and not just one parameter at a time.

    ↳ astro-ph.COhep-phAstropart.Phys.(2021)·606 citations
22. 22*

    Cosmology Intertwined IV: The Age of the Universe and its Curvature

    Eleonora Di Valentino🇬🇧 · Luis A. Anchordoqui🇺🇸 · Ozgur Akarsu🇹🇷 · Yacine Ali-Haimoud🇺🇸 · Luca Amendola🇩🇪 · Nikki Arendse🇩🇰 · Marika Asgari🇬🇧 · Mario Ballardini🇮🇹 · Spyros Basilakos🇬🇷 · Elia Battistelli🇮🇹 · Micol Benetti🇮🇹 · Simon Birrer🇺🇸 and 79 other authors

    A precise measurement of the curvature of the Universe is of primeval importance for cosmology since it could not only confirm the paradigm of primordial inflation but also help in discriminating between different early Universe scenarios. The recent observations, while broadly consistent with a spatially flat standard $\Lambda$ Cold Dark Matter ($\Lambda$CDM) model, are showing tensions that still allow (and, in some cases, even suggest) a few percent deviations from a flat universe. In particular, the Planck Cosmic Microwave Background power spectra, assuming the nominal likelihood, prefer a closed universe at more than 99\% confidence level. While new physics could be in action, this anomaly may be the result of an unresolved systematic error or just a statistical fluctuation. However, since a positive curvature allows a larger age of the Universe, an accurate determination of the age of the oldest objects provides a smoking gun in confirming or falsifying the current flat $\Lambda$CDM model.

    ↳ astro-ph.COhep-phAstropart.Phys.(2021)·113 citations
23. 23*

    Incoherent deeply virtual Compton scattering off ${}^4$He

    Sara Fucini🇮🇹 · Sergio Scopetta🇮🇹 · Michele Viviani🇮🇹

    Very recently, for the first time, the two channels of nuclear deeply virtual Compton scattering (DVCS), the coherent and incoherent ones, have been separated by the CLAS collaboration at JLab, using a ${}^4$He target. The incoherent channel, which can provide a tomographic view of the bound proton and shed light on its elusive parton structure, is thoroughly analyzed here in Impulse Approximation (IA). A convolution formula for the cross sections in terms of those for the bound proton is derived. Novel scattering amplitudes for a bound moving nucleon have been obtained and used. A state-of-the-art nuclear spectral function, based on the AV18 potential, exact in the two-body part, with the recoiling system in its ground state, and modelled in the remaining contribution, with the recoiling system in an excited state, has been used. Different parametrizations of the generalized parton distributions of the struck proton have been tested. A good overall agreement with the data for the beam spin asymmetry (BSA) is obtained. It is found that the predicted conventional nuclear effects are relevant in DVCS and in the competing Bethe-Heitler mechanism, but they cancel each other to a large extent in their ratio, to which the measured asymmetry is proportional. Besides, the calculated ratio of the BSA of the bound proton to that of the free one does not describe that estimated by the experimental collaboration. This points to possible interesting effects beyond the IA analysis presented here. It is therefore clearly demonstrated that the comparison of the results of a conventional realistic approach, as the one presented here, with future precise data, has the potential to expose quark and gluon effects in nuclei. Interesting perspectives for the next measurements at high luminosity facilities, such as JLab at 12 GeV and the future EIC, are addressed.

    ↳ nucl-thhep-phPRC(2020)·9 citations
24. 24*

    Status, Challenges and Directions in Indirect Dark Matter Searches

    Carlos Pérez de los Heros🇸🇪

    Indirect searches for dark matter are based on detecting an anomalous flux of photons, neutrinos or cosmic-rays produced in annihilations or decays of dark matter candidates gravitationally accumulated in heavy cosmological objects, like galaxies, the Sun or the Earth. Additionally, evidence for dark matter that can also be understood as indirect can be obtained from early universe probes, like fluctuations of the Cosmic Microwave Background temperature, the primordial abundance of light elements or the Hydrogen 21-cm line. The techniques needed to detect these different signatures require very different types of detectors: air shower arrays, gamma- and X-ray telescopes, Cherenkov telescopes, neutrino telescopes, radio telescopes or particle detectors in balloons or satellites. Although many of these detectors were not originally intended to search for dark matter, they have proven to be unique complementary tools to the direct search efforts. In this review we summarize the current status of indirect searches for dark matter, mentioning also the challenges and limitations that these techniques encounter.

    ↳ astro-ph.HEhep-exhep-phSymmetry(2020)·126 citations
25. 25*

    Spontaneous Non-Hermiticity in Nambu-Jona-Lasinio model

    M.N. Chernodub🇫🇷 · Alberto Cortijo🇪🇸 · Marco Ruggieri🇨🇳

    We explore the physical consequences of a scenario when the standard Hermitian Nambu--Jona-Lasinio (NJL) model spontaneously develops a non-Hermitian PT-symmetric ground state via dynamical generation of an anti-Hermitian Yukawa coupling. We demonstrate the emergence of a noncompact non-Hermitian (NH) symmetry group which characterizes the NH ground state. We show that the NH group is spontaneously broken both in weak- and strong-coupling regimes. In the chiral limit at strong coupling, the NH ground state develops inhomogeneity, which breaks the translational symmetry. At weak coupling, the NH ground state is a spatially uniform state, which lies at the boundary between the PT-symmetric and PT-broken phases. Outside the chiral limit, the minimal NJL model does not possess a stable non-Hermitian ground state.

    ↳ hep-thcond-mat.mes-hallcond-mat.str-elhep-phPRD(2021)·18 citations
26. 26*

    Sensitivity of the Polyakov loop and related observables to chiral symmetry restoration

    David Anthony Clarke🇩🇪 · Olaf Kaczmarek🇩🇪 · Frithjof Karsch🇩🇪 · Anirban Lahiri🇩🇪 · Mugdha Sarkar🇩🇪

    While the Polyakov loop is an order parameter of the deconfinement transition in the heavy quark mass regime of QCD, its sensitivity to the deconfinement of light, dynamical quarks in QCD is not apparent. On the other hand, the quark mass dependence of the Polyakov loop is sensitive to the appearance of a chiral phase transition. Using lattice QCD calculations in the staggered fermion discretization scheme at finite values of the lattice spacing, $aT=1/8$, we show here, for the first time, that the Polyakov loop expectation value, and the heavy quark free energy extracted from it, behave like energy-like observables in the vicinity of the chiral phase transition temperature $T_c$. Consistent with scaling behavior of energy-like observables in the 3-$d$, O(2) universality class, the quark mass derivatives diverge in the chiral limit at $T_c$ while the temperature derivatives stay finite. The latter will develop a characteristic spike at $T_c$. This, however, may be resolved only in calculations with quark masses being two orders of magnitude smaller than those currently accessible in lattice QCD calculations.

    ↳ hep-lathep-phnucl-thPRD(2021)·36 citations
27. 27*

    Large-N Expansion and String Theory Out of Equilibrium

    Petr Horava🇺🇸 · Christopher J. Mogni🇺🇸

    We analyze the large-$N$ expansion of general non-equilibrium systems with fluctuating matrix degrees of freedom and $SU(N)$ symmetry, using the Schwinger-Keldysh formalism and its closed real-time contour with a forward and backward component. In equilibrium, the large-$N$ expansion of such systems leads to a sum over topologies of two-dimensional surfaces of increasing topological complexity, predicting the possibility of a dual description in terms of string theory. We extend this argument away from equilibrium, and study the universal features of the topological expansion in the dual string theory. We conclude that in non-equilibrium string perturbation theory, the sum over worldsheet topologies is further refined: Each worldsheet surface $\Sigma$ undergoes a triple decomposition into the part ${\Sigma }^{+}$ corresponding to the forward branch of the time contour, the part ${\Sigma }^{-}$ on the backward branch, and the part ${\Sigma }^{\wedge }$ that corresponds to the instant in the far future where the two branches of the time contour meet. The sum over topologies becomes a sum over the triple decompositions. We generalize our findings to the Kadanoff-Baym time contour relevant for systems at finite temperature, and to the case of closed and open, oriented or unoriented strings. Our results are universal, and follow solely from the features of the large-$N$ expansion without any assumptions about the worldsheet dynamics.

    ↳ hep-thastro-ph.COcond-mat.otherhep-ph+2PRD(2022)·15 citations
28. 28*

    CFT Unitarity and the AdS Cutkosky Rules

    David Meltzer🇺🇸 · Allic Sivaramakrishnan🇺🇸

    We derive the Cutkosky rules for conformal field theories (CFTs) at weak and strong coupling. These rules give a simple, diagrammatic method to compute the double-commutator that appears in the Lorentzian inversion formula. We first revisit weakly-coupled CFTs in flat space, where the cuts are performed on Feynman diagrams. We then generalize these rules to strongly-coupled holographic CFTs, where the cuts are performed on the Witten diagrams of the dual theory. In both cases, Cutkosky rules factorize loop diagrams into on-shell sub-diagrams and generalize the standard S-matrix cutting rules. These rules are naturally formulated and derived in Lorentzian momentum space, where the double-commutator is manifestly related to the CFT optical theorem. Finally, we study the AdS cutting rules in explicit examples at tree level and one loop. In these examples, we confirm that the rules are consistent with the OPE limit and that we recover the S-matrix optical theorem in the flat space limit. The AdS cutting rules and the CFT dispersion formula together form a holographic unitarity method to reconstruct Witten diagrams from their cuts.

    ↳ hep-thgr-qchep-phJHEP(2020)·103 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.