Thu·Nov 28, 2019Thursday·November 28, 2019

1. 01*

   Freeze-in production of dark matter through spin-1 and spin-2 portals

   Maíra Dutra🇨🇦

   In this conference, I have talked about two scenarios in which the out-of-equilibrium production of dark matter (DM) particles in the early universe is unavoidable. In the first one \cite{bhattacharyya_freezing-dark_2018}, we extend the standard model (SM) of particle physics by an extra $U(1)$ gauge group under which all the SM particles are neutral. We then consider DM candidates interacting only with the new spin-1 gauge boson, a heavy $Z^{\prime }$. We assume the presence of heavy beyond the SM fermions charged under both extra $U(1)$ and SM $SU(3{)}_c$, allowing for a feeble connection between DM and gluons. In the second scenario \cite{bernal_spin-2_2018}, we assume that the interactions between DM and SM particles are only mediated by gravitons and massive spin-2 fields, being therefore suppressed by the Planck and some intermediate scales, respectively. In both models, we show that the SM particles are able to produce the right amount of DM candidates via freeze-in at most in the early stages of the radiation era, for DM mass in the range $10^{-3}-10^{14}$ GeV. We have shown that if heavy mediators were produced on-shell within a period of entropy production in the early universe, as in the post-inflationary reheating, the DM relic density may be enhanced by many orders of magnitude relative to the usual instantaneous reheating approximation.

   hep-phastro-ph.COPoS(2019)·12 citations
2. 02*

   The moduli portal to dark matter particles

   Maíra Dutra🇨🇦

   The out-of-equilibrium production of dark matter (DM) from standard model (SM) species in the early universe (freeze-in mechanism) is expected in many scenarios in which very heavy beyond the SM fields act as mediators. In this conference, I have talked about the freeze-in of scalar, fermionic and vector DM though the exchange of moduli fields \cite{chowdhury_moduli_2019}, which are in the low-energy spectrum of many extra-dimensions and string theory frameworks. We have shown that the high-temperature dependencies of the production rate densities in this model, as well as the possibility of having moduli masses at the post-inflationary reheating scale, make it crucial to consider the contribution of the freeze-in prior the start of the standard radiation era for a correct prediction of the DM relic density.

   hep-phastro-ph.CO8 citations
3. 03*

   New Perspectives on Axion Misalignment Mechanism

   Chia-Feng Chang🇺🇸 · Yanou Cui🇺🇸

   A zero initial velocity of the axion field is assumed in the conventional misalignment mechanism. We propose an alternative scenario where the initial velocity is nonzero, which may arise from an explicit breaking of the PQ symmetry in the early Universe. We demonstrate that, depending on the specifics about the initial velocity and the time order of the PQ symmetry breaking vs. inflation, this new scenario can alter the conventional prediction for the axion relic abundance in different, potentially significant ways. As a result, new viable parameter regions for axion dark matter may open up.

   hep-phastro-ph.COPRD(2020)·94 citations
4. 04*

   Light (anti-)nuclei and (anti-)hypertriton production in $pp$ collisions at $\sqrt{s}=0.90,2.76$ and $7$ TeV

   Nserdin A. Ragab🇨🇳 · Zhi-Lei She🇨🇳 · Gang Chen🇨🇳

   Production of light (anti-)nuclei and (anti-)hypertriton within midrapidity ($|y|<0.5$) and $p_T<3.0$ GeV/c in $pp$ interactions at $\sqrt{s}$ = 0.90, 2.76 and 7 TeV is investigated by the dynamically constrained phase space coalescence model (DCPC), combined with {\footnotesize{PACIAE}} model. The ALICE data for yields, ratios, as well as transverse momentum distributions of $\overline{d}$ and $d$ are well reproduced by the model simulations, meanwhile the three basic characters of ${}^3\overline{\mathrm{He}}$, ${}^3\mathrm{He}$, ${}_{\overline{\mathrm{\Lambda }}}^3\overline{\mathrm{H}}$, and ${}_{\mathrm{\Lambda }}^3\mathrm{H}$ are also predicted. Besides, we found the yields of light (anti-)nuclei produced are dependent upon their mass number $A$, namely, their yields sharply decrease with the increasing of $A$. The strangeness population factor $s_3=({}_{\mathrm{\Lambda }}^3\mathrm{H}/{}^3\mathrm{He})/(\Lambda /p)$ is found to be about 0.7 $\sim$ 0.8, and is comparable with the available experimental results.

   hep-phnucl-thEur.Phys.J.Plus(2020)·5 citations
5. 05*

   New narrow LHCb pentaquarks as lowest antiquark-diquark-diquark systems

   A.N. Semenova🇷🇺 · V.V. Anisovich🇷🇺 · A.V. Sarantsev🇷🇺

   The antiquark-diquark-diquark model describes pentaquark states both in terms of quarks and hadrons. We discuss pentaquark states with hidden charm $P(\bar{c}cuud)$ discovered in the $J/\Psi p$ spectrum by the LHCb collaboration. We consider three pentaquark states as members of the lowest ($S$-wave) multiplet and discuss the mass splitting scheme. The latest LHCb data for pentaquarks with hidden charm provide an opportunity to make an assumption about the diquark content of the pentaquark states. We give a classification for the LHCb pentaquarks and define recombination channels for these states.

   hep-phEPJA(2020)·9 citations
6. 06*

   The partonic structure of the electron at the next-to-leading logarithmic accuracy in QED

   V. Bertone🇮🇹 · M. Cacciari🇫🇷 · S. Frixione🇮🇹 · G. Stagnitto🇫🇷

   By working in QED, we obtain the electron, positron, and photon Parton Distribution Functions (PDFs) of the unpolarised electron at the next-to-leading logarithmic accuracy. The PDFs account for all of the universal effects of initial-state collinear origin, and are key ingredients in the calculations of cross sections in the so-called structure-function approach. We present both numerical and analytical results, and show that they agree extremely well with each other. The analytical predictions are defined by means of an additive formula that matches a large-$z$ solution that includes all orders in the QED coupling constant $\alpha$, with a small- and intermediate-$z$ solution that includes terms up to $\mathcal{O}({\alpha }^3)$.

   hep-phJHEP(2020)·77 citations
7. 07*

   Asymmetric tri-bi-maximal mixing and residual symmetries

   Salvador Centelles Chuliá🇪🇸 · Andreas Trautner🇩🇪

   Asymmetric tri-bi-maximal mixing is a recently proposed, grand unified theory (GUT) based, flavor mixing scheme. In it, the charged lepton mixing is fixed by the GUT connection to down-type quarks and a ${\mathcal{T}}_{13}$ flavor symmetry, while neutrino mixing is assumed to be tri-bi-maximal (TBM) with one additional free phase. Here we show that this additional free phase can be fixed by the residual flavor and CP symmetries of the effective neutrino mass matrix. We discuss how those residual symmetries can be unified with ${\mathcal{T}}_{13}$ and identify the smallest possible unified flavor symmetries, namely $({\mathbb{Z}}_{13}\times {\mathbb{Z}}_{13})⋊{\mathrm{D}}_{12}$ and $({\mathbb{Z}}_{13}\times {\mathbb{Z}}_{13})⋊{\mathrm{S}}_4$. Sharp predictions are obtained for lepton mixing angles, CP violating phases and neutrinoless double beta decay.

   hep-phhep-exMod.Phys.Lett.A(2020)·6 citations
8. 08*

   Infrared renormalon effects in color dipole TMD PDF at small-$x$

   Nahid Vasim🇮🇳 · Raktim Abir🇮🇳

   The uncertainties from the infrared renormalons in the (color dipole) gluon distribution is estimated. It is shown that non-linear saturation effects at small-$x$ shift the first IR pole at the Borel plane from $2/{\beta }_2$ to $1/{\beta }_2$. As a consequence the estimated uncertainty is found to be $\mathcal{O}\left({\Lambda }_{\mathrm{QCD}}^2\right)$ instead of $\mathcal{O}\left({\Lambda }_{\mathrm{QCD}}^4\right)$.

   hep-phhep-thnucl-thNPB(2020)·1 citation
9. 09*

   Particle emission and gravitational radiation from cosmic strings: observational constraints

   P. Auclair🇫🇷 · D.A. Steer🇫🇷 · T. Vachaspati🇺🇸

   We account for particle emission and gravitational radiation from cosmic string loops to determine their effect on the loop distribution and observational signatures of strings. The effect of particle emission is that the number density of loops no longer scales. This results in a high frequency cutoff on the stochastic gravitational wave background, but we show that the expected cutoff is outside the range of current and planned detectors. Particle emission from string loops also produces a diffuse gamma ray background that is sensitive to the presence of kinks and cusps on the loops. However, both for kinks and cusps, and with mild assumptions about particle physics interactions, current diffuse gamma-ray background observations do not constrain $G\mu$.

   hep-phastro-ph.COPRD(2020)·71 citations
10. 10*

    Higgs boson emerging from the dark

    Chengfeng Cai🇨🇳 · Hong-Hao Zhang🇨🇳 · Giacomo Cacciapaglia🇫🇷 · Mads T. Frandsen🇩🇰 · Martin Rosenlyst🇩🇰

    We propose a new non-thermal mechanism of dark matter production based on vacuum misalignment. A global $X$-charge asymmetry is generated at high temperatures, under which both the will-be Higgs and the dark matter are charged. At lower energies, the vacuum changes alignment and breaks the $U(1{)}_X$, leading to the emergence of the Higgs and of a fraction of charge asymmetry stored in the stable dark matter relic. This mechanism can be present in a wide variety of models based on vacuum misalignment, and we demonstrate it in a composite Higgs template model, where all the necessary ingredients are naturally present. A light pseudo-scalar $\eta$ is always predicted, with interesting implications for cosmology, future supernova observations and exotic $Z\to \gamma \eta$ decays.

    hep-phastro-ph.COhep-exPRL(2020)·19 citations
11. 11*

    Quark condensate seesaw mechanism for neutrino mass

    A. Babič🇨🇿 · S. Kovalenko🇨🇱 · M. I. Krivoruchenko🇷🇺 · F. Šimkovic🇸🇰

    We study a mechanism of generation of Majorana neutrino mass due to spontaneous breaking of chiral symmetry (SBCS) accompanied by the formation of a quark condensate. The effect of the condensate is transmitted to the neutrino sector via Lepton-Number Violating (LNV) lepton-quark dimension-$7$ operators known in the literature as an origin of the neutrino-mass-independent mechanism of neutrinoless double-beta ($0\nu \beta \beta$) decay. The smallness of neutrino masses is due to a large ratio between the LNV scale and the scale of the SBCS. This is a new realization of the seesaw mechanism, which we dub the Quark Condensate SeeSaw (QCSS). We examine the predictions of the QCSS for $0\nu \beta \beta$-decay and neutrino mass spectrum. We will show that our model predicts the normal neutrino mass ordering and narrow ranges of the neutrino masses.

    hep-phnucl-thPRD(2021)·10 citations
12. 12*

    Medium-induced cascade in expanding media

    Souvik Priyam Adhya🇨🇿 · Carlos A. Salgado🇪🇸 · Martin Spousta🇨🇿 · Konrad Tywoniuk🇳🇴

    Detailed insight into the interplay between parton energy loss and the way deconfined medium created in heavy-ion collisions expands is of great importance for improving the understanding of the jet quenching phenomenon. In this paper we study the impact of the expansion of deconfined medium on the single-gluon emission spectrum, its resummation and the jet suppression factor ($Q_{AA}$) within the BDMPS-Z formalism. We calculate these quantities for three types of expansion scenarios, namely static, exponentially decaying and Bjorken expanding media. The distribution of medium-induced gluons is calculated using an evolution equation with splitting kernels derived from the gluon emission spectra. A universal behavior of splitting kernels is derived in the regime of soft gluon emissions when evaluated at a common effective evolution time ${\tau }_{eff}$. Novel scaling features of the resulting gluon distribution and jet $Q_{AA}$ are discussed. For realistic spectra valid beyond the soft-gluon emission limit, where the results are obtained by a numerical solution of the evolution equation, these features are partially replaced by a scaling expected from considering an averaged jet quenching parameter along the trajectory of propagation. Further we show that differences arising from different types of the medium expansion can be to a large extent scaled out by appropriate choice of the quenching parameter. Sizable differences among the values of the quenching parameter for different types of medium expansion point to the importance of the medium expansion for precise modeling of the jet quenching phenomenon.

    hep-phJHEP(2020)·43 citations
13. 13*

    Constraints on long-lived light scalars with flavor-changing couplings and the KOTO anomaly

    P. S. Bhupal Dev🇺🇸 · Rabindra N. Mohapatra🇺🇸 · Yongchao Zhang🇺🇸

    Recently, the KOTO experiment at J-PARC has observed three anomalous events in the flavor-changing rare decay $K_L\to {\pi }^0\nu \bar{\nu }$, which indicates that the corresponding branching ratio is almost two orders of magnitude larger than the Standard Model (SM) prediction. Taking this intriguing result at face value, we explore model implications of its viable explanation by a long-lived light SM-singlet scalar ($S$) emission, i.e. $K_L\to {\pi }^{0}S$, with $S$ decaying outside the KOTO detector. We derive constraints on the parameter space of such a light scalar in the context of three simple models: (i) a real singlet scalar extension of the SM; (ii) a $B-L$ extension where neutrino masses arise via type-I seesaw mechanism from $B-L$ breaking; and (iii) a TeV-scale left-right symmetric model. The flavor-changing couplings needed to explain the KOTO excess in models (i) and (ii) originate from tree-level mixing of the scalar with SM Higgs field ($h$), and in model (iii), from the mixing of $S$ and $h$ with the neutral component of the heavy bidoublet Higgs field. After taking into account the stringent constraints from high-precision searches for flavor-changing charged and neutral kaon decays at NA62, E949, KOTO and CHARM experiments, as well as the astrophysical and cosmological constraints on a light scalar, such as those from supernova energy loss, big bang nucleosynthesis and relativistic degrees of freedom, we find that the light scalar interpretation of the KOTO excess is allowed in all these models. Parts of the parameter range can be tested in future NA62 and DUNE experiments.

    hep-phhep-exPRD(2020)·60 citations
14. 14*

    Asymmetric Matters from a Dark First-Order Phase Transition

    Eleanor Hall🇺🇸 · Thomas Konstandin🇩🇪 · Robert McGehee🇺🇸 · Hitoshi Murayama🇺🇸

    We introduce a model for matters-genesis in which both the baryonic and dark matter asymmetries originate from a first-order phase transition in a dark sector with an $SU(3)\times SU(2)\times U(1)$ gauge group and minimal matter content. In the simplest scenario, we predict that dark matter is a dark antineutron with mass either $m_{\bar{n}}=1.36$ GeV or $m_{\bar{n}}=1.63$ GeV. Alternatively, dark matter may be comprised of equal numbers of dark antiprotons and pions. This model, in either scenario, is highly discoverable through both dark matter direct detection and dark photon search experiments. The strong dark matter self interactions may ameliorate small-scale structure problems, while the strongly first-order phase transition may be confirmed at future gravitational wave observatories.

    hep-phastro-ph.COPRD(2023)·123 citations
15. 15*

    The High Quality QCD Axion and the LHC

    Anson Hook🇺🇸 · Soubhik Kumar🇺🇸 · Zhen Liu🇺🇸 · Raman Sundrum🇺🇸

    The QCD axion provides an elegant solution to the Strong CP Problem. While the minimal realization is vulnerable to the so-called "Axion Quality Problem", we will consider a more robust realization in the presence of a mirror sector related to the Standard Model by a (softly broken) ${\mathbb{Z}}_2$ symmetry. We point out that the resulting "heavy" axion, while satisfying all theoretical and observational constraints, has a large and uncharted parameter space which allows it to be probed at the LHC as a Long-Lived Particle (LLP). The small defining axionic coupling to gluons results in a challenging hadronic decay signal which we argue can be distinguished against the background in such a long-lived regime, and yet, the same coupling allows for sufficient production at hadron colliders thanks to the large gluon parton luminosity. Our study opens up a new window towards accelerator observable axions, and more generally, singly produced LLPs.

    hep-phhep-exPRL(2020)·172 citations
16. 16*

    A Preference for Cold Dark Matter over Superfluid Dark Matter in Local Milky Way Data

    Mariangela Lisanti🇺🇸 · Matthew Moschella🇺🇸 · Nadav Joseph Outmezguine🇮🇱 · Oren Slone🇺🇸

    There are many well-known correlations between dark matter and baryons that exist on galactic scales. These correlations can essentially be encompassed by a simple scaling relation between observed and baryonic accelerations, historically known as the Mass Discrepancy Acceleration Relation (MDAR). The existence of such a relation has prompted many theories that attempt to explain the correlations by invoking additional fundamental forces on baryons. The standard lore has been that a theory that reduces to the MDAR on galaxy scales but behaves like cold dark matter (CDM) on larger scales provides an excellent fit to data, since CDM is desirable on scales of clusters and above. However, this statement should be revised in light of recent results showing that a fundamental force that reproduces the MDAR is challenged by local Milky Way dynamics and rotation curve data between 5-18 kpc. In this study, we test this claim on the example of Superfluid Dark Matter. We find that a standard CDM model is preferred over a static superfluid profile assuming a steady-state Galactic disk and discuss the robustness of this conclusion to disequilibrium effects. This preference is due to the fact that the superfluid model over-predicts vertical accelerations, even while reproducing galactic rotation curves. Our results establish an important criterion that any dark matter model must satisfy within the Milky Way.

    hep-phastro-ph.COastro-ph.GAPhys.Dark Univ.(2023)·15 citations
17. 17*

    Goldstone Equivalence and High Energy Electroweak Physics

    Gabriel Cuomo🇨🇭 · Luca Vecchi🇨🇭 · Andrea Wulzer🇨🇭

    The transition between the broken and unbroken phases of massive gauge theories, namely the rearrangement of longitudinal and Goldstone degrees of freedom that occurs at high energy, is not manifestly smooth in the standard formalism. The lack of smoothness concretely shows up as an anomalous growth with energy of the longitudinal polarization vectors, as they emerge in Feynman rules both for real on-shell external particles and for virtual particles from the decomposition of the gauge field propagator. This makes the characterization of Feynman amplitudes in the high-energy limit quite cumbersome, which in turn poses peculiar challenges in the study of Electroweak processes at energies much above the Electroweak scale. We develop a Lorentz-covariant formalism where polarization vectors are well-behaved and, consequently, energy power-counting is manifest at the level of individual Feynman diagrams. This allows us to prove the validity of the Effective W Approximation and, more generally, the factorization of collinear emissions and to compute the corresponding splitting functions at the tree-level order. Our formalism applies at all orders in perturbation theory, for arbitrary gauge groups and generic linear gauge-fixing functionals. It can be used to simplify Standard Model loop calculations by performing the high-energy expansion directly on the Feynman diagrams. This is illustrated by computing the radiative corrections to the decay of the top quark.

    hep-phhep-thSciPost Phys.(2020)·35 citations
18. 18*

    High-precision nuclear forces from chiral EFT: State-of-the-art, challenges and outlook

    E. Epelbaum🇩🇪 · H. Krebs🇩🇪 · P. Reinert🇩🇪

    We review a new generation of nuclear forces derived in chiral effective field theory using the recently proposed semilocal regularization method. We outline the conceptual foundations of nuclear chiral effective field theory, discuss all steps needed to compute nuclear observables starting from the effective chiral Lagrangian and consider selected applications in the two- and few-nucleon sectors. We highlight key challenges in developing high-precision tree-body forces, such as the need to maintain consistency between two- and many-body interactions and constraints placed by the chiral and gauge symmetries after regularization.

    ↳ nucl-thhep-phnucl-exFront.in Phys.(2020)·178 citations
19. 19*

    Form factors with two operator insertions and the principle of maximal transcendentality

    Taushif Ahmed🇩🇪 · Pulak Banerjee🇨🇭 · Amlan Chakraborty🇮🇳 · Prasanna K. Dhani🇮🇹 · V. Ravindran🇮🇳

    We present the first calculations of two-point two-loop form factors (FFs) with a two identical operators insertion in maximally supersymmetric Yang-Mills theory. In this article, we consider the supersymmetry protected half-BPS primary and unprotected Konishi operators. Unlike the FFs of a single operator insertion of the half-BPS primary, the FFs involving two half-BPS operators are found to contain lower transcendentality weight terms in addition to the highest ones. Moreover, in contrast to Sudakov FFs, the highest weight terms of the FFs of a double half-BPS no longer match with that of a double Konishi. We also find that the principle of maximal transcendentality, which dictates the presence of identical highest weight terms in the scalar FFs of half-BPS and quark/gluon FFs in QCD, does not hold true anymore for insertions of two identical operators. We discover the absence of any additional ultraviolet counterterm that could arise from the contact interaction between two composite operators.

    ↳ hep-thhep-phPRD(2020)·13 citations
20. 20*

    Novel matter coupling in Einstein gravity

    Chunshan Lin🇵🇱 · Zygmunt Lalak🇵🇱

    A general framework of the novel matter coupling in the Einstein gravity is introduced. We firstly prove that a class of theories whose Hamiltonian constraint is given by an arbitrary function $f(H_g)$, where $H_g$ is the Hamiltonian constraint of general relativity (GR), is equivalent to GR in the vaccum. A novel Jordan frame is defined when GR is rewritte in terms of one of its equivalents in this class. The transformation between the novel Jordan frame and the Eintein frame is a redifinition of lapse. We discuss two types of consistency condition for matter to couple to Einstein gravity in the novel Jordan frame. The Type I consistency condition is found by demanding all constraints to be first class; the type II consistency condition is found by demanding the algebra is closed when matter minimally couples to gravity in the novel Jordan frame, which an additional gauge condition is required. We discuss the cosmological implications from these two types of matter coupling.

    ↳ gr-qcastro-ph.COhep-phhep-th7 citations
21. 21*

    Vectorizing Quantum Turbulence Vortex-Core Lines for Real-Time Visualization

    Daoming Liu · Chi Xiong🇨🇳 · Xiaopei Liu🇬🇧

    Vectorizing vortex-core lines is crucial for high-quality visualization and analysis of turbulence. While several techniques exist in the literature, they can only be applied to classical fluids. Recently, quantum fluids with turbulence get more and more attention in physics. It is thus desirable that vortex-core lines can also be well extracted and visualized for quantum fluids. In this paper, we aim for this goal and developed an efficient vortex-core line vectorization method for quantum fluids, which enables real-time visualization of high-resolution quantum turbulence structure. Given the datasets by simulation, our technique is developed from the vortices identified by the circulation-based method. To vectorize the vortex-core lines enclosed by those vortices, we propose a novel graph-based data structure, with iterative graph reduction and density-guided local optimization, to locate more precisely sub-grid-scale vortex-core line samples, which are then vectorized by continuous curves. This not only represents vortex-core line structures continuously, but also naturally preserves complex topology, such as branching during reconnection. By vectorization, the memory consumption can be largely reduced by orders of magnitude, enabling real-time rendering performance. Different types of interactive visualizations are demonstrated to show the effectiveness of our technique, which could assist further research on quantum turbulence.

    ↳ cs.GRcond-mat.quant-gashep-phnlin.CD0 citations
22. 22*

    Conformal Invariance of the One-Loop All-Plus Helicity Scattering Amplitudes

    Johannes Henn🇩🇪 · Bláithín Power🇩🇪 · Simone Zoia🇩🇪

    The massless QCD Lagrangian is conformally invariant and, as a consequence, so are the tree-level scattering amplitudes. However, the implications of this powerful symmetry at loop level are only beginning to be explored systematically. Even for finite loop amplitudes, the way conformal symmetry manifests itself may be subtle, e.g. in the form of anomalous conformal Ward identities. As they are finite and rational, the one-loop all-plus and single-minus amplitudes are a natural first step towards understanding the conformal properties of Yang-Mills theory at loop level. Remarkably, we find that the one-loop all-plus amplitudes are conformally invariant, whereas the single-minus are not. Moreover, we present a formula for the one-loop all-plus amplitudes where the symmetry is manifest term by term. Surprisingly, each term transforms covariantly under directional dual conformal variations. We prove the formula directly using recursive techniques, and check that it has the correct physical factorisations.

    ↳ hep-thhep-phJHEP(2020)·29 citations
23. 23*

    Exploring the QCD phase diagram via reweighting from isospin chemical potential

    Bastian B. Brandt🇩🇪 · Francesca Cuteri🇩🇪 · Gergely Endrodi🇩🇪 · Sebastian Schmalzbauer🇩🇪

    We investigate the QCD phase diagram for small values of baryon and strange quark chemical potentials from simulations at non-zero isospin chemical potential. Simulations at pure isospin chemical potential are not hindered by the sign problem and pion condensation can be observed for sufficiently large isospin chemical potentials. We study how the related phase boundary evolves with baryonic and strange chemical potentials via reweighting in quark chemical potentials and discuss our results. Furthermore, we propose and implement an alternative method to approach nonzero baryon (and strange quark) chemical potentials. This method involves simulations where physical quarks are paired with auxiliary quarks in unphysical "isospin" doublets and a decoupling of the auxiliary quarks by mass reweighting.

    ↳ hep-lathep-phnucl-thPoS(2019)·10 citations
24. 24*

    Causality, unitarity, and indefinite metric in Maxwell-Chern-Simons extensions

    Ricardo Avila🇨🇱 · Jose R. Nascimento🇧🇷 · Albert Yu. Petrov🇧🇷 · Carlos M. Reyes🇨🇱 · Marco Schreck🇧🇷

    We canonically quantize $(2+1)$-dimensional electrodynamics including a higher-derivative Chern-Simons term. The effective theory describes a standard photon and an additional degree of freedom associated with a massive ghost. We find the Hamiltonian and the algebra satisfied by the field operators. The theory is characterized by an indefinite metric in the Hilbert space that brings up questions on causality and unitarity. We study both of the latter fundamental properties and show that microcausality as well as perturbative unitarity up to one-loop order are conserved when the Lee-Wick prescription is employed.

    ↳ hep-thhep-phPRD(2020)·16 citations
25. 25*

    Evading the model sign problem in the PNJL model with repulsive vector-type interaction via path optimization

    Akira Ohnishi🇯🇵 · Yuto Mori🇯🇵 · Kouji Kashiwa🇯🇵

    We discuss the sign problem in the Polyakov loop extended Nambu--Jona-Lasinio model with repulsive vector-type interaction by using the path optimization method. In this model, both of the Polyakov loop and the vector-type interaction cause the model sign problem, and several prescriptions have been utilized even in the mean field treatment. In the path optimization method, integration variables are complexified and the integration path (manifold) is optimized to evade the sign problem, or equivalently to enhance the average phase factor. Within the homogeneous field ansatz, the path is optimized by using the feedforward neural network. We find that the assumptions adopted in previous works, $\mathrm{Re}{A}_8\simeq 0$ and $\mathrm{Re}\omega \simeq 0$, can be justified from the Monte-Carlo configurations sampled on the optimized path. We also derive the Euler-Lagrange equation for the optimal path to satisfy. The two optimized paths, the solution of the Euler-Lagrange equation and the variationally optimized path, agree with each other in the region with large statistical weight.

    ↳ hep-lathep-phnucl-thPoS(2019)·1 citation
26. 26*

    Scattering in strong electromagnetic fields: transverse size effects in tBLFQ

    Bolun Hu🇨🇳 · Anton Ilderton🇬🇧 · Xingbo Zhao🇨🇳

    The framework of 'time-dependent basis light-front quantisation' (tBLFQ) offers a non-perturbative approach to scattering problems in external fields, based on Fock space truncation. Here we extend tBLFQ to include spatio-temporal field inhomogeneities in multiple spacetime directions. This extension is necessary for the proper modelling of e.g. intense laser fields. We focus on the example of nonlinear Compton scattering of an electron on an axicon-type laser, with an emphasis on the transverse structure of the beam. We analyse the impact of field intensity and particle energy, as well as basis truncation effects, on the radiation spectrum of the scattered electron.

    ↳ nucl-thhep-phPRD(2020)·16 citations
27. 27*

    A New Mask for An Old Suspect: Testing the Sensitivity of the Galactic Center Excess to the Point Source Mask

    Yi-Ming Zhong🇺🇸 · Samuel D. McDermott🇺🇸 · Ilias Cholis🇺🇸 · Patrick J. Fox🇺🇸

    The Fermi-LAT collaboration has recently released a new point source catalog, referred to as 4FGL. For the first time, we perform a template fit using information from this new catalog and find that the Galactic center excess is still present. On the other hand, we find that a wavelet-based search for point sources is highly sensitive to the use of the 4FGL catalog: no excess of bright regions on small angular scales is apparent when we mask out 4FGL point sources. We postulate that the 4FGL catalog contains the large majority of bright point sources that have previously been suggested to account for the excess in gamma rays detected at the Galactic center in Fermi-LAT data. Furthermore, after identifying which bright sources have no known counterpart, we place constraints on the luminosity function necessary for point sources to explain the smooth emission seen in the template fit.

    ↳ astro-ph.HEastro-ph.COhep-phPRL(2020)·69 citations
28. 28*

    Do we have any hope of detecting scattering between dark energy and baryons through cosmology?

    Sunny Vagnozzi🇬🇧 · Luca Visinelli🇳🇱 · Olga Mena🇪🇸 · David F. Mota🇳🇴

    We consider the possibility that dark energy and baryons might scatter off each other. The type of interaction we consider leads to a pure momentum exchange, and does not affect the background evolution of the expansion history. We parametrize this interaction in an effective way at the level of Boltzmann equations. We compute the effect of dark energy-baryon scattering on cosmological observables, focusing on the Cosmic Microwave Background (CMB) temperature anisotropy power spectrum and the matter power spectrum. Surprisingly, we find that even huge dark energy-baryon cross-sections ${\sigma }_{xb}\sim \mathcal{O}(\mathrm{b})$, which are generically excluded by non-cosmological probes such as collider searches or precision gravity tests, only leave an insignificant imprint on the observables considered. In the case of the CMB temperature power spectrum, the only imprint consists in a sub-percent enhancement or depletion of power (depending whether or not the dark energy equation of state lies above or below $-1$) at very low multipoles, which is thus swamped by cosmic variance. These effects are explained in terms of differences in how gravitational potentials decay in the presence of a dark energy-baryon scattering, which ultimately lead to an increase or decrease in the late-time integrated Sachs-Wolfe power. Even smaller related effects are imprinted on the matter power spectrum. The imprints on the CMB are not expected to be degenerate with the effects due to altering the dark energy sound speed. We conclude that, while strongly appealing, the prospects for a direct detection of dark energy through cosmology do not seem feasible when considering realistic dark energy-baryon cross-sections. As a caveat, our results hold to linear order in perturbation theory.

    ↳ gr-qcastro-ph.COhep-phMNRAS(2020)·99 citations
29. 29*

    Radial flow induced by inhomogeneous magnetic field in heavy ion collisions

    Mohsen Haddadi Moghaddam🇮🇹 · Behnam Azadegan🇮🇷 · Ahmad Farzaneh Kord🇮🇷 · Wanda M. Alberico🇮🇹

    In this paper, we study the effects of an in-homogeneous magnetic field on the quark gluon plasma dynamics, within the Magneto-Hydrodynamic framework. We have investigated the effect of an inhomogeneous external magnetic field on the transverse expansion of in-viscid fluid created in high energy nuclear collisions. Transverse velocity and energy density are modified by the presence of the magnetic field. This effects can also influence the transverse momentum spectrum for particles at the freeze-out surface. In this context we obtained an interesting comparison with data extracted from heavy-ion collisions.

    ↳ nucl-thhep-phSpringer Proc.Phys.(2020)·0 citations
30. 30*

    Effects of oscillating spacetime metric background on a complex scalar field and formation of topological vortices

    Shreyansh S. Dave🇮🇳 · Sanatan Digal🇮🇳

    We study the time evolution of a complex scalar field in the symmetry broken phase in the presence of oscillating spacetime metric background. In our (2+1)-dimensional simulations, we show that the spacetime oscillations can excite an initial field configuration, which ultimately leads to the formation of topological vortices in the system. At late times, field configuration achieves a disordered state. A detailed study of the momentum and frequency modes of the field reveals that these field excitations are driven by the phenomenon of parametric resonance. In extremely high frequency regime where frequency of spacetime oscillations is much larger than the field-mass, the formed vortices are not topological in nature. Interestingly in this regime, for a suitable choice of parameters of the simulation, we observe a persistent lattice structure of vortex-antivortex pairs. We discuss applications of our study to the dynamics of interior superfluidity of neutron stars during binary neutron star mergers, in generation of excitation in ultralight axion-like field near a strong gravitational wave source, etc.

    ↳ hep-thastro-ph.HEcond-mat.quant-gashep-ph+1PRD(2021)·5 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.