Tue·Apr 13, 2021Tuesday·April 13, 2021

1. 01*

   Constraining electroweak and strongly charged long-lived particles with CheckMATE

   Nishita Desai🇮🇳 · Florian Domingo🇩🇪 · Jong Soo Kim🇿🇦 · Roberto Ruiz de Austri Bazan🇪🇸 · Krzysztof Rolbiecki🇵🇱 · Mangesh Sonawane🇦🇹 · Zeren Simon Wang🇹🇼

   Long-lived particles have become a new frontier in the exploration of physics beyond the Standard Model. In this paper, we present the implementation of four types of long-lived particle searches, viz. displaced leptons, disappearing track, displaced vertex (together with muons or with missing energy), and heavy charged tracks. These four categories cover the signatures of a large range of physics models. We illustrate their potential for exclusion and discuss their mutual overlaps in mass-lifetime space for two simple phenomenological models involving either a U(1)-charged or a coloured scalar.

   hep-phEPJC(2021)·24 citations
2. 02*

   Understanding Event-Generation Networks via Uncertainties

   Marco Bellagente🇩🇪 · Manuel Haußmann🇩🇪 · Michel Luchmann🇩🇪 · Tilman Plehn🇩🇪

   Following the growing success of generative neural networks in LHC simulations, the crucial question is how to control the networks and assign uncertainties to their event output. We show how Bayesian normalizing flow or invertible networks capture uncertainties from the training and turn them into an uncertainty on the event weight. Fundamentally, the interplay between density and uncertainty estimates indicates that these networks learn functions in analogy to parameter fits rather than binned event counts.

   hep-phcs.LGSciPost Phys.(2022)·77 citations
3. 03*

   Fermion masses and mixings and $g-2$ muon anomaly in a 3-3-1 model with $D_4$ family symmetry

   A. E. Cárcamo Hernández🇨🇱 · H. N. Long🇻🇳 · M. L. Mora-Urrutia🇨🇱 · N. H. Thao🇻🇳 · V. V. Vien🇻🇳

   We propose a predictive model based on the $SU(3{)}_C\times SU(3{)}_L\times U(1{)}_X$ gauge symmetry, which is supplemented by the $D_4$ family symmetry and several auxiliary cyclic symmetries whose spontaneous breaking produces the observed SM fermion mass and mixing pattern. The masses of the light active neutrinos are produced by an inverse seesaw mechanism mediated by three right handed Majorana neutrinos. To the best of our knowledge the model corresponds to the first implementation of the $D_4$ family symmetry in a $SU(3{)}_C\times SU(3{)}_L\times U(1{)}_X$ theory with three right handed Majorana neutrinos and inverse seesaw mechanism. Our proposed model successfully accommodates the experimental values of the SM fermion mass and mixing parameters, the muon anomalous magnetic moment as well as the Higgs diphoton decay rate and meson oscillations constraints. The consistency of our model with the muon anomalous magnetic moment requires charged exotic vector like leptons at the TeV scale.

   hep-phEPJC(2022)·14 citations
4. 04*

   Improved Bounds on Lorentz Symmetry Violation From High-Energy Astrophysical Sources

   Brett Altschul🇺🇸

   Observations of the synchrotron and inverse Compton emissions from ultrarelativistic electrons in astrophysical sources can reveal a great deal about the energy-momentum relations of those electrons. They can thus be used to place bounds on the possibility of Lorentz violation in the electron sector. Recent $\gamma$-ray telescope data allow the Lorentz-violating electron $c^{\nu \mu }$ parameters to be constrained extremely well, so that all bounds are at the level of $7\times 10^{-16}$ or better.

   hep-phastro-ph.HESymmetry(2021)·8 citations
5. 05*

   Pion form factor from an AdS deformed background

   Miguel Angel Martin Contreras🇨🇱 · Eduardo Folco Capossoli🇧🇷 · Danning Li🇨🇳 · Alfredo Vega🇨🇱 · Henrique Boschi-Filho🇧🇷

   We consider a bottom-up AdS/QCD model with a conformal exponential deformation $e^{k{z}^2}$ on a Lorentz invariant AdS background. In this model, we assume the conformal dimension associated with the operator that creates pions at the boundary as $\Delta =3$. Regarding the infrared scale related to photon field $k_{\gamma }$, we analyze two cases: constant and depending on the transferred momentum $q$. In these two cases, we computed the electromagnetic pion form factor as well as the pion radius. We compare our results with experimental data as well as other theoretical (holographic and non-holographic) models. In particular, for the momentum-dependent infrared scale, we find good agreement with the available experimental data as well as non-holographic models.

   hep-phhep-thnucl-thNPB(2022)·21 citations
6. 06*

   A quantum strategy to compute the jet quenching parameter $\hat{q}$

   João Barata🇪🇸 · Carlos A. Salgado🇪🇸

   Jet quenching, the modification of the properties of a QCD jet when the parton cascade takes place inside a medium, is an intrinsically quantum process, where color coherence effects play an essential role. Despite a very significant progress in the last years, the simulation of a full quantum medium induced cascade remains inaccessible to classical Monte Carlo parton showers. In this situation, alternative formulations are worth being tried and the fast developments in quantum computing provide a very promising direction. The goal of this paper is to introduce a strategy to quantum simulate single particle momentum broadening, the simplest building block of jet quenching. Momentum broadening is the modification of the quark or gluon transverse momentum due interactions with the underlying medium, modeled as a QCD background field. At the lowest order in ${\alpha }_s$ that we consider here, momentum broadening does not involve parton splittings and particle number is conserved, greatly simplifying the quantum algorithmic implementation. This quantity is, however, very relevant for the phenomenology of RHIC, LHC or the future EIC.

   hep-phquant-phEPJC(2021)·37 citations
7. 07*

   Nonanalyticity, sign problem and Polyakov line in Z3-symmetric heavy quark model at low temperature: Phenomenological model analyses

   Hiroaki Kouno🇯🇵 · Kouji Kashiwa🇯🇵 · Takehiro Hirakida🇯🇵

   The nonanalyticity and the sign problem in the Z3-symmetric heavy quark model at low temperature are studied phenomenologically. For the free heavy quarks, the nonanalyticity is analyzed in the relation to the zeros of the grand canonical partition function. The Z3-symmetric effective Polyakov-line model (EPLM) in strong coupling limit is also considered as an phenomenological model of Z3-symmetric QCD with large quark mass at low temperature. We examine how the Z3-symmetric EPLM approaches to the original one in the zero-temperature limit. The effects of the Z3-symmetry affect the structure of zeros of the microscopic probability density function at the nonanalytic point. The average value of the Polyakov line can detect the structure, while the other thermodynamic quantities are not sensible to the structure in the zero-temperature limit. The effect of the imaginary quark chemical potential is also discussed. The imaginary part of the quark number density is very sensitive to the symmetry structure at the nonanalytical point. For a particular value of the imaginary quark number chemical potential, large quark number may be induced in the vicinity of the nonanalytical point.

   hep-phhep-latnucl-thPRD(2021)·1 citation
8. 08*

   Shedding Light on Dark Matter and Neutrino Interactions from Cosmology

   Arnab Paul🇮🇳 · Arindam Chatterjee🇮🇳 · Anish Ghoshal🇮🇹 · Supratik Pal🇮🇳

   In $\mathrm{\Lambda }$CDM cosmology, Dark Matter (DM) and neutrinos are assumed to be non-interacting. However, it is possible to have scenarios, where DM-neutrino interaction may be present, leading to scattering of DM with neutrinos and annihilation of DM into neutrinos. We investigate the viability of such scenarios in the light of cosmological data by making use of the Planck 2018 dataset (high-l TT+TE+EE, low-l TT, low-l EE) and constrain these processes in the light of the same. We also discuss a viable particle DM model where DM-neutrino interaction is present, and map the constraints obtained to the parameter space of the model.

   hep-phastro-ph.COJCAP(2021)·22 citations
9. 09*

   Exploring the Early Universe with Gaia and THEIA

   Juan Garcia-Bellido🇪🇸 · Hitoshi Murayama🇺🇸 · Graham White🇯🇵

   It has recently been pointed out that Gaia is capable of detecting a stochastic gravitational wave background in the sensitivity band between the frequency of pulsar timing arrays and LISA. We argue that Gaia and THEIA has great potential for early universe cosmology, since such a frequency range is ideal for probing phase transitions in asymmetric dark matter, SIMP and the cosmological QCD transition. Furthermore, there is the potential for detecting primordial black holes in the solar mass range produced during such an early universe transition and distinguish them from those expected from the QCD epoch. Finally, we discuss the potential for Gaia and THEIA to probe topological defects and the ability of Gaia to potentially shed light on the recent NANOGrav results.

   hep-phastro-ph.COJCAP(2021)·162 citations
10. 10*

    Magnetogenesis From Baryon Asymmetry During an Early Matter Dominated Era

    Fatemeh Elahi🇩🇪 · Hadi Mehrabpour🇯🇵

    In this paper, we study the simultaneous evolution of baryon asymmetry and hypermagnetic field amplitude assuming an early matter domination. We contrast our results to the conventional case where radiation domination during early universe is assumed. We show that the baryon asymmetry and the hypermagntic field amplitude can change by orders of magnitude if we assume a non-standard history of cosmology. That is because the Hubble rate determines which processes are efficient. We find that a change in Hubble rate can have a significant impact on when the weak sphalerons become active. As a result of a change in the evolution of baryonic asymmetry, alters the evolution of hypermagnetic field amplitude. It is known that if the hypermagnetic field amplitude is large enough, it can save the baryon asymmetry from diminishing. We show that whether a small seed of hypermagnetic field amplitude can be amplified to a large enough value will strongly depend on the history of cosmology.

    hep-phPRD(2021)·5 citations
11. 11*

    New physics in the angular distribution of $B_c^{-}\to J/\psi (\to {\mu }^{+}{\mu }^{-}){\tau }^{-}(\to {\pi }^{-}{\nu }_{\tau }){\bar{\nu }}_{\tau }$ decay

    Quan-Yi Hu🇨🇳 · Xin-Qiang Li🇨🇳 · Xiao-Long Mu🇨🇳 · Ya-Dong Yang🇨🇳 · Dong-Hui Zheng🇨🇳

    In $B_c^{-}\to J/\psi (\to {\mu }^{+}{\mu }^{-}){\tau }^{-}{\bar{\nu }}_{\tau }$ decay, the three-momentum ${\mathbf{p}}_{{\tau }^{-}}$ cannot be determined accurately due to the decay products of ${\tau }^{-}$ inevitably include an undetected ${\nu }_{\tau }$. As a consequence, the angular distribution of this decay cannot be measured. In this work, we construct a {\it measurable} angular distribution by considering the subsequent decay ${\tau }^{-}\to {\pi }^{-}{\nu }_{\tau }$. The full cascade decay is $B_c^{-}\to J/\psi (\to {\mu }^{+}{\mu }^{-}){\tau }^{-}(\to {\pi }^{-}{\nu }_{\tau }){\bar{\nu }}_{\tau }$, in which the three-momenta ${\mathbf{p}}_{{\mu }^{+}}$, ${\mathbf{p}}_{{\mu }^{-}}$, and ${\mathbf{p}}_{{\pi }^{-}}$ can be measured. The five-fold differential angular distribution containing all Lorentz structures of the new physics (NP) effective operators can be written in terms of twelve angular observables ${\mathcal{I}}_i(q^2,E_{\pi })$. Integrating over the energy of pion $E_{\pi }$, we construct twelve normalized angular observables ${\hat{\mathcal{I}}}_i(q^2)$ and two lepton-flavor-universality ratios $R(P_{L,T}^{J/\psi })(q^2)$. Based on the $B_c\to J/\psi$ form factors calculated by the latest lattice QCD and sum rule, we predict the $q^2$ distribution of all ${\hat{\mathcal{I}}}_i$ and $R(P_{L,T}^{J/\psi })$ both within the Standard Model and in eight NP benchmark points. We find that the benchmark BP2 (corresponding to the hypothesis of tensor operator) has the greatest effect on all ${\hat{\mathcal{I}}}_i$ and $R(P_{L,T}^{J/\psi })$, except ${\hat{\mathcal{I}}}_5$. The ratios $R(P_{L,T}^{J/\psi })$ are more sensitive to the NP with pseudo-scalar operators than the ${\hat{\mathcal{I}}}_i$. Finally, we discuss the symmetries in the angular observables and present a model-independent method to determine the existence of tensor operators.

    hep-phJHEP(2021)·8 citations
12. 12*

    Generating function for nucleus-nucleus scattering amplitudes in Glauber theory

    Yu.M. Shabelski🇷🇺 · A.G. Shuvaev🇷🇺

    A new approach to deal with the scattering amplitudes in Glauber theory is proposed. It relies on the use of generating function, that has been explicitly found. The method is applied to the analytical calculation of the nucleus-nucleus elastic scattering amplitudes in the all interaction orders of the Glauber theory.

    hep-phnucl-thPRC(2021)·9 citations
13. 13*

    Charged current electroproduction of a charmed meson at an electron-ion collider

    B.Pire🇫🇷 · L.Szymanowski🇵🇱 · J.Wagner🇵🇱

    We calculate the amplitude for exclusive electroweak production of a pseudoscalar $D_s$ or a vector $D_s^{\ast }$ charmed strange meson on an unpolarized nucleon, through a charged current, in leading order in ${\alpha }_s$. We work in the framework of the collinear QCD approach where generalized gluon distributions factorize from perturbatively calculable coefficient functions. We include both $O(m_c)$ terms in the coefficient functions and $O(M_D)$ mass term contributions in the heavy meson distribution amplitudes. We show that this process may be accessed at future electron-ion colliders.

    hep-phPRD(2021)·19 citations
14. 14*

    Revisiting semileptonic decays of ${\Lambda }_{b(c)}$ supported by baryon spectroscopy

    Yu-Shuai Li🇨🇳 · Xiang Liu🇨🇳 · Fu-Sheng Yu🇨🇳

    The semileptonic decays of ${\Lambda }_b\to {\Lambda }_c^{(\ast )}\ell {\nu }_{\ell }$ and ${\Lambda }_c\to {\Lambda }^{(\ast )}\ell {\nu }_{\ell }$ are studied in the light-front quark model in this work. Instead of the quark-diquark approximation, we use the three-body wave functions obtained by baryon spectroscopy. The ground states $(1/2^{+})$, the $\lambda$-mode orbital excited states $(1/2^{-})$, and the first radial excited states $(1/2^{+})$ of ${\Lambda }_{(c)}^{(\ast )}$ are considered. The discussions are given for the form factors, partial widths, branching fractions, leptonic forward-backward asymmetries, hadron polarizations, lepton polarizations, and the lepton flavor universalities. Our results are useful for the inputs of heavy baryon decays and understanding the baryon structures, and helpful for experimental measurements.

    hep-phPRD(2021)·54 citations
15. 15*

    Flavor Specific $U(1{)}_{B_q-L_{\mu }}$ Gauge Model for Muon $g-2$ and $b\to s\bar{\mu }\mu$ Anomalies

    Jian-Yong Cen🇨🇳 · Yu Cheng🇨🇳 · Xiao-Gang He🇨🇳 · Jin Sun🇨🇳

    The muon $(g-2{)}_{\mu }$ and $b\to s\bar{\mu }\mu$ induced $B$ anomalies as hints of new physics beyond the standard model (SM) have attracted much attention. These two anomalies indicate that there may exist new interaction specifically related to muon. A lot of theoretical ideas have been proposed to explain these anomalies. Gauged flavor specific $U(1{)}_{B_q-L_{\mu }}$ is among the promising ones. The new gauge boson $Z^{\prime }$ from $U(1{)}_{B_q-L_{\mu }}$ interacts with muon and provides necessary ingredient to solve the $(g-2{)}_{\mu }$ anomaly. The $Z^{\prime }$-quark coupling can generate flavor changing interactions after diagonalization of quark mass matrix between weak eigen-state and mass eigen-state basis. We revisit challenges for such models attempting to explain the $(g-2{)}_{\mu }$ and $B$ anomalies separately or simultaneously. We find although for $U(1{)}_{B_q-L_{\mu }}$ models there is still parameter space to provide solutions for separately explaining the $(g-2{)}_{\mu }$ and $B$ anomalies, there exists no parameter space for such models to solve both the anomalies simultaneously, after taking into account existing constraints from $\tau \to \mu \gamma$, $\tau \to 3\mu$, neutrino trident and $B_s-{\bar{B}}_s$ data. Among them leptonic processes restrict $Z^{\prime }$ mass to be less than a few hundred MeV if required to solve the $(g-2{)}_{\mu }$ anomaly, which causes conflict between data from $B_s-{\bar{B}}_s$, $D^0-{\bar{D}}^0$ mixing and also hadron decays with $Z^{\prime }$ in the final states. The effects of $U(1{)}_Y$ and $U(1{)}_{B_q-L_{\mu }}$ kinetic mixing on these anomalies are also studied. We find that neither can these effects do much to bring the two anomalies together to be solved simultaneously.

    hep-phNPB(2022)·40 citations
16. 16*

    The effects of non-helical component of hypermagnetic field on the evolution of the matter-antimatter asymmetry, vorticity, and hypermagnetic field

    S. Abbaslu🇮🇷 · S. Rostam Zadeh🇮🇷 · A. Rezaei🇮🇷 · S. S. Gousheh🇮🇷

    We study the evolution of the matter-antimatter asymmetry ({\eta}), the vorticity, and the hypermagnetic field in the symmetric phase of the early Universe, and in the temperature range 100 GeV < T < 10 TeV. We assume a configuration for the hypermagnetic field which includes both helical and non-helical (Bz) components. Consequently, the hypermagnetic field and the fluid vorticity can directly affect each other, the manifestations of which we explore in three scenarios. In the first scenario, we show that in the presence of a small vorticity and a large {\eta}eR, helicity can be generated and amplified for an initially strong Bz. The generation of the helical seed is due to the chiral vortical effect (CVE) and/or the advection term, while its growth is mainly due to the chiral magnetic effect (CME) which leads to the production of the baryon asymmetry, as well. The vorticity saturates to a nonzero value which depends on Bz, even in the presence of the viscosity, due to the back-reaction of Bz on the plasma. Increasing the initial vorticity, makes the values of the helicity, {\eta}s, and vorticity reach their saturation curves sooner, but does not change their final values at the onset of the electroweak phase transition. The second scenario is similar to the first except we assume that all initial {\eta}s are zero. We find that much higher initial vorticity is required for the generation process. In the third scenario, we show that in the presence of only a strong hypermagnetic field, {\eta}s and vorticity can be generated and amplified. Increasing the initial helicity, increases the final {\eta}s and vorticity. We find that although the presence of a nonzero initial Bz is necessary in all three scenarios, its increase only increases the final values of vorticity.

    hep-phPRD(2021)·7 citations
17. 17*

    Vacuum birefringence and diffraction at XFEL: from analytical estimates to optimal parameters

    Elena A. Mosman🇷🇺 · Felix Karbstein🇩🇪

    We study vacuum birefringence and x-ray photon scattering in the head-on collision of x-ray free electron and high-intensity laser pulses. Resorting to analytical approximations for the numbers of attainable signal photons, we analyze the behavior of the phenomenon under the variation of various experimental key-parameters and provide new analytical scalings. Our optimized approximations allow for quantitatively accurate results on the one-percent level. We in particular demonstrate that an appropriate choice of the x-ray focus and pulse duration can significantly improve the signal for given laser parameters, using the experimental parameters to be available at the Helmholtz International Beamline for Extreme Fields at the European XFEL as example. Our results are essential for the identification of the optimal choice of parameters in a discovery experiment of vacuum birefringence at the high-intensity frontier.

    hep-phquant-phPRD(2021)·25 citations
18. 18*

    Prospects for macroscopic dark matter detection at space-based and suborbital experiments

    Luis A. Anchordoqui🇺🇸 · Mario E. Bertaina🇮🇹 · Marco Casolino🇮🇹 · Johannes Eser🇺🇸 · John F. Krizmanic🇺🇸 · Angela V. Olinto🇺🇸 · A. Nepomuk Otte🇺🇸 · Thomas C. Paul🇺🇸 · Lech W. Piotrowski🇵🇱 · Mary Hall Reno🇺🇸 · Fred Sarazin🇺🇸 · Kenji Shinozaki🇵🇱 and 3 other authors

    We compare two different formalisms for modeling the energy deposition of macroscopically sized/massive quark nuggets (a.k.a. macros) in the Earth's atmosphere. We show that for a reference mass of 1 g, there is a discrepancy in the macro luminosity of about 14 orders of magnitude between the predictions of the two formalisms. Armed with our finding we estimate the sensitivity for macro detection at space-based (Mini-EUSO and POEMMA) and suborbital (EUSO-SPB2) experiments.

    hep-phastro-ph.HEEPL(2021)·12 citations
19. 19*

    Weighted $\sin \left(3{\varphi }_h-{\varphi }_S\right)$ asymmetry from pretzelosity in SIDIS at electron ion colliders

    Shi-Chen xue🇨🇳 · Xiaoyu Wang🇨🇳 · De-Min Li🇨🇳 · Zhun Lu🇨🇳

    We investigate the transverse momentum weighted azimuthal asymmetry with a $\sin \left(3{\varphi }_h-{\varphi }_S\right)$ modulation in electroproduction of charged pion production off the transversely polarized proton. The asymmetry is contributed by the product of the second transverse-moment of the pretzelosity distribution function and the first transverse-moment of the Collins function. Using the extracted result for the proton pretzelosity and the available parametrization for the pion Collins function, we numerically predict the $P_{hT}^3$-weighted $\sin \left(3{\varphi }_h-{\varphi }_S\right)$ asymmetry for charged pion production at electron ion colliders (EICs). It is found that the weighted asymmetry is around 2 percent in the kinematics region of EICs. Our results show that the planned high luminosity electron ion colliders could be feasible to access pretzelosity in the near future.

    hep-phPLB(2021)·6 citations
20. 20*

    Induced surface and curvature tension equation of state for hadron resonance gas in finite volumes and its relation to morphological thermodynamics

    K. A. Bugaev🇺🇦 · O. V. Vitiuk🇺🇦 · B. E. Grinyuk🇺🇦 · P. P. Panasiuk🇺🇦 · N. S. Yakovenko🇺🇦 · E. S. Zherebtsova🇷🇺 · V. V. Sagun🇵🇹 · O. I. Ivanytskyi🇵🇱 · L. V. Bravina🇳🇴 · D. B. Blaschke🇵🇱 · S. Kabana🇨🇱 · S. V. Kuleshov🇨🇱 and 3 other authors

    Here we develop an original approach to investigate the grand canonical partition function of the multicomponent mixtures of Boltzmann particles with hard-core interaction in finite and even small systems of the volumes above 20 fm${}^3$. The derived expressions of the induced surface tension equation of state are analyzed in details. It is shown that the metastable states, which can emerge in the finite systems with realistic interaction, appear at very high pressures at which the hadron resonance gas, most probably, is not applicable at all. It is shown how and under what conditions the obtained results for finite systems can be generalized to include into a formalism the equation for curvature tension. The applicability range of the obtained equations of induced surface and curvature tensions for finite systems is discussed and their close relations to the equations of the morphological thermodynamics are established. The hadron resonance gas model on the basis of the obtained advanced equation of state is worked out. Also, this model is applied to analyze the chemical freeze-out of hadrons and light nuclei with the number of (anti-)baryons not exceeding 4, including the most problematic ratios of hyper-triton and its antiparticle. Their multiplicities were measured by the ALICE Collaboration in the central lead-lead collisions at the center-of-mass energy $\sqrt{s_{\mathrm{NN}}}=$ 2.76 TeV.

    hep-phInt.J.Mod.Phys.A(2021)·4 citations
21. 21*

    Simiplified textures of the seesaw model for the trimaximal neutrino mixings

    Zhen-hua Zhao🇨🇳 · Xin-Yu Zhao🇨🇳 · Hui-Chao Bao🇨🇳

    In the seesaw framework, in the basis of $M_{\mathrm{R}}^{}$ being diagonal, we explore the simplified textures of $M_{\mathrm{D}}^{}$ that can naturally yield the trimaximal neutrino mixings and their consequences for the neutrino parameters and leptogenesis. We first formulate the generic textures of $M_{\mathrm{D}}^{}$ that can naturally yield the trimaximal mixings and then examine if their parameters can be further reduced. Our analysis is restricted to the simple but instructive scenario that there is only one phase parameter $\varphi$ responsible for both the CP violating effects at low energies and leptogenesis. Our attention is paid to the textures of $M_{\mathrm{D}}^{}$ that possess some vanishing or equal elements. On the basis of these results, we further examine if $\varphi$ can also take a particular value. The consequences of the phenomenologically-viable simplified textures for the neutrino parameters and leptogenesis are studied. A concrete flavor-symmetry model that can realize one representation of them is given.

    hep-phPRD(2022)·14 citations
22. 22*

    QCD sum rule analysis of Bottomonium ground states

    Pallabi Parui🇮🇳 · Sourodeep De🇮🇳 · Ankit Kumar🇮🇳 · Amruta Mishra🇮🇳

    The in-medium masses of the bottomonium ground states [$1S$ (${\rm Y}(1S),{\eta }_b$) and $1P$ (${\chi }_{b0},{\chi }_{b1}$)] are investigated in the magnetized vacuum (nuclear medium), using the QCD sum rule framework. In QCD sum rule approach, the mass modifications are calculated in terms of the medium modifications of the scalar and twist-2 gluon condensates, which are obtained in the nuclear medium, from the medium change of a scalar dilaton field, $\chi$ within a chiral effective model. The in-medium masses of the bottomonium ground states are observed to decrease with increasing density. P-wave states are observed to have more appreciable mass-shifts than the S-wave states. In the present investigation, the effects of spin-mixing between 1S bottomonium states, ${\rm Y}(1S)$ and ${\eta }_b$ are taking into account in presence of an external magnetic field. The contribution of magnetic fields are seen to be dominant via spin-magnetic field interaction effects, which leads to an appreciable rise and drop in the in-medium masses of the longitudinal component of vector $1S$ state (${\rm Y}$) and pseudoscalar state (${\eta }_b$) respectively. For zero magnetic field, the effects of baryon density on the bottomonium ground states in isospin asymmetric nuclear medium are observed to be quite appreciable. These should have observable consequences for the production of the open and hidden bottom meson states resulting from high energy asymmetric nuclear collisions in facilities which probe high density baryonic matter. There is observed to be large contributions to the masses of the longitudinal component of the vector bottomonium state, ${\rm Y}(1S)$ and pesudoscalar state ${\eta }_b$ in strong magnetic fields.

    hep-ph13 citations
23. 23*

    On the significance of new physics in $b\to s{\ell }^{+}{\ell }^{-}$ decays

    Gino Isidori🇨🇭 · Davide Lancierini🇨🇭 · Patrick Owen🇨🇭 · Nicola Serra🇨🇭

    Motivated by deviations with respect to Standard Model predictions in $b\to s{\ell }^{+}{\ell }^{-}$ decays, we evaluate the global significance of the new physics hypothesis in this system by including the {\it look-elsewhere effect} for the first time. We estimate the trial-factor with pseudo-experiments and find that it can be as large as seven. We calculate the global significance for the new physics hypothesis by considering the most general description of a non-standard $b\to s{\ell }^{+}{\ell }^{-}$ amplitude of short-distance origin. Theoretical uncertainties are treated in a highly conservative way by absorbing the corresponding effects into a redefinition of the Standard Model amplitude. Using the most recent measurements of LHCb, ATLAS and CMS, we obtain the global significance to be $4.3$ standard deviations.

    hep-phhep-exPLB(2021)·71 citations
24. 24*

    Muon $(g-2)$ and XENON1T Excess with Boosted Dark Matter in $L_{\mu }-L_{\tau }$ Model

    Debasish Borah (1)🇮🇳 · Manoranjan Dutta (2)🇮🇳 · Satyabrata Mahapatra (2)🇮🇳 · Narendra Sahu (2) ((1) Indian Institute of Technology Guwahati, (2) Indian Institute of Technology Hyderabad)🇮🇳

    Motivated by the growing evidence for lepton flavour universality violation after the first results from Fermilab's muon $(g-2)$ measurement, we revisit one of the most widely studied anomaly free extensions of the standard model namely, gauged $L_{\mu }-L_{\tau }$ model, known to be providing a natural explanation for muon $(g-2)$. We also incorporate the presence of dark matter (DM) in this model in order to explain the recently reported electron recoil excess by the XENON1T collaboration. We show that the same neutral gauge boson responsible for generating the required muon $(g-2)$ can also mediate interactions between electron and dark fermions boosted by dark matter annihilation. The required DM annihilation rate into dark fermion require a hybrid setup of thermal and non-thermal mechanisms to generate DM relic density. The tightly constrained parameter space from all requirements remain sensitive to ongoing and near future experiments, keeping the scenario very predictive.

    hep-phastro-ph.COhep-exPLB(2021)·52 citations
25. 25*

    Electromagnetic transition form factors and Dalitz decays of hyperons

    Stefan Leupold (Uppsala U.)🇸🇪 · Nora Salone (Uppsala U. and NCBJ, Warsaw)🇵🇱

    Dalitz decays of a hyperon resonance to a ground-state hyperon and an electron-positron pair can give access to some information about the composite structure of hyperons. We present expressions for the multi-differential decay rates in terms of general transition form factors for spin-parity combinations J^P = 1/2^+/-, 3/2^+/- of the hyperon resonance. Even if the spin of the initial hyperon resonance is not measured, the self-analyzing weak decay of the "final" ground-state hyperon contains information about the relative phase between combinations of transition form factors. This relative phase is non-vanishing because of the unstable nature of the hyperon resonance. If all form factor combinations in the differential decay formulae are replaced by their respective values at the photon point, one obtains a QED type approximation, which might be interpreted as characterizing hypothetical hyperons with point-like structure. We compare the QED type approximation to a more realistic form factor scenario for the lowest-lying singly-strange hyperon resonances. In this way we explore which accuracy in the measurements of the differential Dalitz decay rates is required in order to distinguish the composite-structure case from the pointlike case. Based on the QED type approximation we obtain as a by-product a rough prediction for the ratio between the Dalitz decay width and the corresponding photon decay width.

    hep-phnucl-thEPJA(2021)·11 citations
26. 26*

    Dark matter freeze-in from semi-production

    Andrzej Hryczuk🇵🇱 · Maxim Laletin🇵🇱

    We study a novel dark matter production mechanism based on the freeze-in through semi-production, i.e. the inverse semi-annihilation processes. A peculiar feature of this scenario is that the production rate is suppressed by a small initial abundance of dark matter and consequently creating the observed abundance requires much larger coupling values than for the usual freeze-in. We provide a concrete example model exhibiting such production mechanism and study it in detail, extending the standard formalism to include the evolution of dark matter temperature alongside its number density and discuss the importance of this improved treatment. Finally, we confront the relic density constraint with the limits and prospects for the dark matter indirect detection searches. We show that, even if it was never in full thermal equilibrium in the early Universe, dark matter could, nevertheless, have strong enough present-day annihilation cross section to lead to observable signals.

    hep-phastro-ph.COJHEP(2021)·27 citations
27. 27*

    A vector leptoquark interpretation of the muon $g-2$ and $B$ anomalies

    Mingxuan Du🇨🇳 · Jinhan Liang🇨🇳 · Zuowei Liu🇨🇳 · Van Que Tran🇨🇳

    We show that a single vector leptoquark can explain both the muon $g-2$ anomaly recently measured by the Muon g-2 experiment at Fermilab, and the various $B$ decay anomalies, including the $R_{D^{(\ast )}}$ and $R_{K^{(\ast )}}$ anomalies which have been recently reported by the LHCb experiment. In order to provide sizeable positive new physics contributions to the muon $g-2$, we assume that the vector leptoquark particle couples to both left-handed and right-handed fermions with equal strength. Our model is found to satisfy the experimental constraints from the large hadron collider.

    hep-ph32 citations
28. 28*

    Three-Body Decays of Heavy Dirac and Majorana Fermions

    André de Gouvêa🇺🇸 · Patrick J. Fox🇺🇸 · Boris J. Kayser🇺🇸 · Kevin J. Kelly🇺🇸

    Nonzero neutrino masses imply the existence of degrees of freedom and interactions beyond those in the Standard Model. A powerful indicator of what these might be is the nature of the massive neutrinos: Dirac fermions versus Majorana fermions. While addressing the nature of neutrinos is often associated with searches for lepton-number violation, there are several other features that distinguish Majorana from Dirac fermions. Here, we compute in great detail the kinematics of the daughters of the decays into charged-leptons and neutrinos of hypothetical heavy neutral leptons at rest. We allow for the decay to be mediated by the most general four-fermion interaction Lagrangian. We demonstrate, for example, that when the daughter charged-leptons have the same flavor or the detector is insensitive to their charges, polarized Majorana-fermion decays have zero forward/backward asymmetry in the direction of the outgoing neutrino (relative to the parent spin), whereas Dirac-fermion decays can have large asymmetries. Going beyond studying forward/backward asymmetries, we also explore the fully-differential width of the three-body decays. It contains a wealth of information not only about the nature of the new fermions but also the nature of the interactions behind their decays.

    hep-phhep-exPRD(2021)·32 citations
29. 29*

    Searching for Leptoquarks at Future Muon Colliders

    Pouya Asadi🇺🇸 · Rodolfo Capdevilla🇨🇦 · Cari Cesarotti🇺🇸 · Samuel Homiller🇺🇸

    A high energy muon collider can provide new and complementary discovery potential to the LHC or future hadron colliders. Leptoquarks are a motivated class of exotic new physics models, with distinct production channels at hadron and lepton machines. We study a vector leptoquark model at a muon collider with $\sqrt{s}=3,14$ TeV within a set of both UV and phenomenologically motivated flavor scenarios. We compute which production mechanism has the greatest reach for various values of the leptoquark mass and the coupling between leptoquark and Standard Model fermions. We find that we can probe leptoquark masses up to an order of magnitude beyond $\sqrt{s}$ with perturbative couplings. Additionally, we can also probe regions of parameter space unavailable to flavor experiments. In particular, all of the parameter space of interest to explain recent low-energy anomalies in B meson decays would be covered even by a $\sqrt{s}=3$ TeV collider.

    hep-phJHEP(2021)·90 citations
30. 30*

    Axion-like Particles from Hypernovae

    Andrea Caputo🇮🇱 · Pierluca Carenza🇮🇹 · Giuseppe Lucente🇮🇹 · Edoardo Vitagliano🇺🇸 · Maurizio Giannotti🇺🇸 · Kei Kotake🇯🇵 · Takami Kuroda🇩🇪 · Alessandro Mirizzi🇮🇹

    It was recently pointed out that very energetic subclasses of supernovae (SNe), like hypernovae and superluminous SNe, might host ultra-strong magnetic fields in their core. Such fields may catalyze the production of feebly interacting particles, changing the predicted emission rates. Here we consider the case of axion-like particles (ALPs) and show that the predicted large scale magnetic fields in the core contribute significantly to the ALP production, via a coherent conversion of thermal photons. Using recent state-of-the-art SN simulations including magnetohydrodynamics, we find that if ALPs have masses $m_a\sim \mathcal{O}(10)\mathrm{MeV}$, their emissivity via magnetic conversions is over two orders of magnitude larger than previously estimated. Moreover, the radiative decay of these massive ALPs would lead to a peculiar delay in the arrival times of the daughter photons. Therefore, high-statistics gamma-ray satellites can potentially discover MeV ALPs in an unprobed region of the parameter space and shed light on the magnetohydrodinamical nature of the SN explosion.

    hep-phastro-ph.HEPRL(2021)·41 citations
31. 31*

    A Minimal Explanation of Flavour Anomalies: B-Meson Decays, Muon Magnetic Moment, and the Cabibbo Angle

    David Marzocca🇮🇹 · Sokratis Trifinopoulos🇮🇹

    Significant deviations from the Standard Model are observed in semileptonic charged and neutral-current B-decays, the muon magnetic moment, and the extraction of the Cabibbo angle. We propose that these deviations point towards a coherent pattern of New Physics effects induced by two scalar mediators, a leptoquark $S_1$ and a charged singlet ${\varphi }^{+}$. While $S_1$ can provide solutions to charged-current $B$-decays and the muon magnetic moment, and ${\varphi }^{+}$ can accommodate the Cabibbo-angle anomaly independently, their one-loop level synergy can also address neutral-current $B$-decays. This framework provides the most minimal explanation to the above-mentioned anomalies, while being consistent with all other phenomenological constraints.

    hep-phPRL(2021)·91 citations
32. 32*

    Scale-Invariant Quadratic Gravity and Inflation in the Palatini Formalism

    Ioannis D. Gialamas🇬🇷 · Alexandros Karam🇪🇪 · Thomas D. Pappas🇨🇿 · Vassilis C. Spanos🇬🇷

    In the framework of classical scale invariance, we consider quadratic gravity in the Palatini formalism and investigate the inflationary predictions of the theory. Our model corresponds to a two-field scalar-tensor theory, that involves the Higgs field and an extra scalar field stemming from a gauge $U(1{)}_X$ extension of the Standard Model, which contains an extra gauge boson and three right-handed neutrinos. Both scalar fields couple nonminimally to gravity and induce the Planck scale dynamically, once they develop vacuum expectation values. By means of the Gildener-Weinberg approach, we describe the inflationary dynamics in terms of a single scalar degree of freedom along the flat direction of the tree-level potential. The one-loop effective potential in the Einstein frame exhibits plateaus on both sides of the minimum and thus the model can accommodate both small and large field inflation. The inflationary predictions of the model are found to comply with the latest bounds set by the Planck collaboration for a wide range of parameters and the effect of the quadratic in curvature terms is to reduce the value of the tensor-to-scalar ratio.

    ↳ astro-ph.COgr-qchep-phhep-thPRD(2021)·71 citations
33. 33*

    Q-balls Formation and the Production of Gravitational Waves With Non-minimal Gravitational Coupling

    Fei Wang🇨🇳 · Rui Wang🇨🇳

    We propose to introduce non-minimal couplings of Affleck-Dine (AD) field to gravity by adding the coupling of AD field to the Ricci scalar curvature. As the Jordan frame supergravity always predict $|\Phi {|}^2\mathcal{R}/6$ type coupling for scalars with canonical kinetic terms, we propose a way to realize the required $c_0|\Phi {|}^2\mathcal{R}$-type couplings with generic $c_0$ for canonical complex scalar fields after SUSY breaking. The impacts of such non-minimal gravitational couplings for AD field is shown, especially on the Q-balls formation and the associated gravitational wave (GW) productions. New form of scalar potential for AD field in the Einstein frame is obtained. By numerical simulations, we find that, with non-minimal gravitational coupling to AD field, Q-balls can successfully form even with the choice of non-negative $K$ parameter for $\xi >0$. The associated GW productions as well as their dependences on the $\xi$ parameter are also discussed.

    ↳ gr-qcastro-ph.COhep-phEPJC(2022)·6 citations
34. 34*

    Cosmological Evolution of Fermi-LAT Gamma-ray Blazars Using Novel Nonparametric Methods

    Houdun Zeng🇨🇳 · Vahé Petrosian🇺🇸 · Tingfeng Yi🇨🇳

    Multi-wavelength analyses of spectra of active galactic nuclei (AGNs) provide useful information on the physical processes in the accretion disk and jets of black holes. This, however, is limited to bright sources and may not represent the population as a whole. Another approach is through the investigation of the cosmological evolution of the luminosity function (LF) that shows varied evolution (luminosity and density) at different wavelengths. These differences and the correlations between luminosities can shed light on the Jet-accretion disk connection. Most such studies use forward fitting parametric methods that involve several functions and many parameters. We use non-parametric, non-binning methods developed by Efron and Petrosian, and Lynden-Bell, for obtaining unbiased description of the evolution of the LF, from data truncated by observational selection effects. We present analysis of the evolution of gamma-ray LF of blazars with main focus on flat spectrum radio quasars (FSRQs). This requires analysis of both gamma-ray and optical data, essential for redshift measurements, and a description of the joint LF. We use a new approach which divides the sample into two sub-samples, each with its own flux limit. We use the Fermi-LAT and GAIA observations, and present results on the gamma-ray LF and its evolution, and determine the intrinsic correlation between the gamma-ray and optical luminosities corrected for the well known false correlation induced by their similar redshift dependence and evolution of the two luminosities. We also present a direct estimation of the contribution of blazars to the spectrum of the extragalactic gamma-ray background.

    ↳ astro-ph.HEhep-phApJ(2021)·19 citations
35. 35*

    Restricted Weyl Symmetry and Spontaneous Symmetry Breakdown of Conformal Symmetry

    Ichiro Oda🇯🇵

    We elucidate the relation between the restricted Weyl symmetry and spontaneous symmetry breakdown of conformal symmetry. Using a scalar-tensor gravity, we show that the restricted Weyl symmetry leads to spontaneous symmetry breakdown of a global scale symmetry when the vacuum expectation value of a scalar field takes a non-zero value. It is then shown that this spontaneous symmetry breakdown induces spontaneous symmetry breakdown of special conformal symmetry in a flat Minkowski space-time, but the resultant Nambu-Goldstone boson is not an independent physical mode but expressed in terms of the derivative of the dilaton which is the Nambu-Goldstone boson of the global scale symmetry. In other words, the theories which are invariant under the general coordinate transformation and the restricted Weyl transformation exhibit a Nambu-Goldstone phase where both special conformal transformation and dilatation are spontaneously broken while preserving the Poincaré symmetry.

    ↳ hep-thgr-qchep-phMod.Phys.Lett.A(2021)·10 citations
36. 36*

    Non-Markovian open quantum system approach to the early universe: I. Damping of gravitational waves by matter

    Moslem Zarei🇮🇷 · Nicola Bartolo🇮🇹 · Daniele Bertacca🇮🇹 · Angelo Ricciardone🇮🇹 · Sabino Matarrese🇮🇹

    By revising the application of the open quantum system approach to the early universe and extending it to the conditions beyond the Markovian approximation, we obtain a new non-Markovian quantum Boltzmann equation. Throughout the paper, we also develop an extension of the quantum Boltzmann equation to describe the processes that are irreversible at the macroscopic level. This new kinetic equation is, in principle, applicable to a wide variety of processes in the early universe. For instance, using this equation one can accurately study the microscopic influence of a cosmic environment on a system of cosmic background photons or stochastic gravitational waves. In this paper, we apply the non-Markovian quantum Boltzmann equation to study the damping of gravitational waves propagating in a medium consisting of decoupled ultra-relativistic neutrinos. For such a system, we study the time evolution of the intensity and the polarization of the gravitational waves. It is shown that, in contrast to intensity and linear polarization which are damped, the circular polarization (V-mode) of the gravitational wave (if present) is amplified by propagating through such a medium.

    ↳ astro-ph.COgr-qchep-phPRD(2021)·31 citations
37. 37*

    Spontaneous Symmetry Breaking in the Phase Space

    Y. Contoyiannis🇬🇷 · S.G. Stavrinides🇬🇷 · M. Kampitakis🇬🇷 · M.P. Hanias🇬🇷 · S.M. Potirakis🇬🇷 · P. Papadopoulos🇬🇷

    In this brief, the spontaneous symmetry breaking (SSB) of the ${\phi }^4$ theory in phase space, is studied. This phase space results from the appropriate system of Poincare maps, produced in both the Minkowski and the Euclidean time. The importance of discretization in the creation of phase space, is highlighted. A series of interesting, novel, unknown behaviors are reported for the first time; among them the most characteristic is the change in stability. In specific, the stable fixed points of the ${\phi }^4$ potential appear as unstable ones, in phase space. Additionally, in the Euclidean-time phase space a unique instability in the position of the critical point, can be created. This instability is further proposed to host tachyonic field in Euclidean space.

    ↳ cond-mat.stat-mechhep-phPhys.Scripta(2021)·3 citations
38. 38*

    Detailed analysis of excited state systematics in a lattice QCD calculation of $g_A$

    Jinchen He🇨🇳 · David A. Brantley🇺🇸 · Chia Cheng Chang🇯🇵 · Ivan Chernyshev🇺🇸 · Evan Berkowitz🇺🇸 · Dean Howarth🇺🇸 · Christopher Körber🇩🇪 · Aaron S. Meyer🇺🇸 · Henry Monge-Camacho🇺🇸 · Enrico Rinaldi🇺🇸 · Chris Bouchard🇬🇧 · M.A. Clark🇺🇸 and 5 other authors

    Excited state contamination remains one of the most challenging sources of systematic uncertainty to control in lattice QCD calculations of nucleon matrix elements and form factors: early time separations are contaminated by excited states and late times suffer from an exponentially bad signal-to-noise problem. High-statistics calculations at large time separations $\gtrsim 1$ fm are commonly used to combat these issues. In this work, focusing on $g_A$, we explore the alternative strategy of utilizing a large number of relatively low-statistics calculations at short to medium time separations (0.2--1 fm), combined with a multi-state analysis. On an ensemble with a pion mass of approximately 310 MeV and a lattice spacing of approximately 0.09 fm, we find this provides a more robust and economical method of quantifying and controlling the excited state systematic uncertainty. A quantitative separation of various types of excited states enables the identification of the transition matrix elements as the dominant contamination. The excited state contamination of the Feynman-Hellmann correlation function is found to reduce to the 1% level at approximately 1 fm while for the more standard three-point functions, this does not occur until after 2 fm. Critical to our findings is the use of a global minimization, rather than fixing the spectrum from the two-point functions and using them as input to the three-point analysis. We find that the ground state parameters determined in such a global analysis are stable against variations in the excited state model, the number of excited states, and the truncation of early-time or late-time numerical data.

    ↳ hep-lathep-phnucl-thPRC(2022)·23 citations
39. 39*

    Cosmology of strongly interacting fermions in the early universe

    Guillem Domènech🇮🇹 · Misao Sasaki🇯🇵

    In view of growing interest in long range scalar forces in the early universe to generate primordial black holes, we study in detail the general relativistic formulation of a Fermi gas interacting with a scalar field in cosmology. Our main finding is that the Yukawa interaction leads to a solution where the scalar field oscillates around zero fermion mass and all energy densities decay as radiation. On one hand, we show that if the Fermi gas starts relativistic, it could stay relativistic. On the other hand, if the fermions are initially non-relativistic, they remain non-relativistic for all practical purposes. We find that in both cases the energy density of the fermions and the scalar field decays as radiation. In the non-relativistic case, this is due to an oscillating and decaying effective mass. Such background dynamics questions whether there is a substantial enhancement of the fermion density fluctuations in the non-relativistic case. Our work can be easily extended to more general field dependent fermion mass. The analysis of the cosmological perturbations will be presented in a follow-up work.

    ↳ hep-thastro-ph.COgr-qchep-phJCAP(2021)·36 citations
40. 40*

    Bubble Wall Velocity from Holography

    Yago Bea🇬🇧 · Jorge Casalderrey-Solana🇪🇸 · Thanasis Giannakopoulos🇵🇹 · David Mateos🇪🇸 · Mikel Sanchez-Garitaonandia🇪🇸 · Miguel Zilhão🇵🇹

    Cosmological phase transitions proceed via the nucleation of bubbles that subsequently expand and collide. The resulting gravitational wave spectrum depends crucially on the bubble wall velocity. Microscopic calculations of this velocity are challenging even in weakly coupled theories. We use holography to compute the wall velocity from first principles in a strongly coupled, non-Abelian, four-dimensional gauge theory. The wall velocity is determined dynamically in terms of the nucleation temperature. We find an approximately linear relation between the velocity and the ratio $\Delta \mathcal{P}/\mathcal{E}$, with $\Delta \mathcal{P}$ the pressure difference between the inside and the outside of the bubble and $\mathcal{E}$ the energy density outside the bubble. Up to a rescaling, the wall profile is well approximated by that of an equilibrium, phase-separated configuration at the critical temperature. We verify that ideal hydrodynamics provides a good description of the system everywhere except near the wall.

    ↳ hep-thastro-ph.COgr-qchep-phPRD(2021)·84 citations
41. 41*

    Bayesian Forecasts for Dark Matter Substructure Searches with Mock Pulsar Timing Data

    Vincent S. H. Lee🇺🇸 · Stephen R. Taylor🇺🇸 · Tanner Trickle🇺🇸 · Kathryn M. Zurek🇺🇸

    Dark matter substructure, such as primordial black holes (PBHs) and axion miniclusters, can induce phase shifts in pulsar timing arrays (PTAs) measurements due to gravitational effects. In order to gain a more realistic forecast for the detectability of such models of dark matter with PTAs, we propose a Bayesian inference framework to search for phase shifts generated by PBHs and perform the analysis on mock PTA data. For most PBH masses the constraints on the dark matter abundance agree with previous (frequentist) analyses (without mock data) to $\mathcal{O}(1)$ factors. This further motivates a dedicated search for PBHs (and dense small scale structures) in the mass range from $10^{-8}{M}_{\odot }$ to well above $10^2{M}_{\odot }$ with the Square Kilometer Array. Moreover, with a more optimistic set of timing parameters, future PTAs are predicted to constrain PBHs down to $10^{-11}{M}_{\odot }$. Lastly, we discuss the impact of backgrounds, such as Supermassive Black Hole Mergers, on detection prospects, suggesting a future program to separate a dark matter signal from other astrophysical sources.

    ↳ astro-ph.COhep-phJCAP(2021)·40 citations
42. 42*

    Constructing angular distributions of neutrinos in core collapse supernova from zero-th and first moments calibrated by full Boltzmann neutrino transport

    Hiroki Nagakura🇺🇸 · Lucas Johns🇺🇸

    Two-moment neutrino transport methods have been widely used for developing theoretical models of core-collapse supernova (CCSN), since they substantially reduce the computational burden inherent in the multi-dimensional neutrino-radiation hydrodynamical simulations. The approximation, however, comes at a price; the detailed structure of angular distribution of neutrinos is sacrificed, that is the main drawback of this approach. In this paper, we develop a novel method by which to construct angular distributions of neutrinos from the zero-th and first angular moments. In our method, the angular distribution is expressed with two quadratic functions of the neutrino angle in a piecewise fashion. We determine the best parameters in the fitting function by comparing to the neutrino data in a spherically symmetric CCSN model with full Boltzmann neutrino transport. We demonstrate the capability of our method by using our recent 2D CCSN model. We find that the essential features of the angular distributions can be well reconstructed, whereas the angular distributions of incoming neutrinos tend to have large errors that increase with flux factor ($\kappa$). This issue originates from the insensitiveness of incoming neutrinos to $\kappa$, that is an intrinsic limitation in moment methods. Based on the results of the demonstration, we assess the reliability of ELN-crossing searches with two-moment neutrino transport. This analysis is complementary to our another paper that scrutinizes the limitation of crossing searches with a few moments. We find that the systematic errors of angular distributions for incoming neutrinos lead to misjudgements of the crossing at $\kappa \gtrsim 0.5$. This casts doubt on the results of ELN-crossing searches based on two-moment methods in some previous studies.

    ↳ astro-ph.HEhep-phPRD(2021)·33 citations
43. 43*

    Minimal Supergravity Inflation without Slow Gravitino

    Takahiro Terada🇰🇷

    We utilize a recently proposed cubic nilpotent superfield to realize inflation in supergravity with the minimal degrees of freedom: the inflaton, graviton, and massive gravitino. As an advantage, the resultant model is free from the catastrophic production of gravitinos due to its vanishing propagation speed. However, the model suffers from the standard gravitino problem, and its viability depends on the mass spectrum and the thermal history of the universe.

    ↳ hep-thastro-ph.COgr-qchep-phPRD(2021)·19 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.