Fri·Aug 13, 2021Friday·August 13, 2021

1. 01*

   Gravitational waves from melting cosmic strings

   William T. Emond🇨🇿 · Sabir Ramazanov🇨🇿 · Rome Samanta🇨🇿

   Appearance of cosmic strings in the early Universe is a common manifestation of new physics typically linked to some high energy scale. In this paper, we discuss a different situation, where a model underlying cosmic string formation is approximately scale free. String tension is naturally related to the square of the temperature of the hot primordial plasma in such a setting, and hence decreases with (cosmic) time. With gravitational backreaction neglected, the dynamics of these melting strings in an expanding Universe is equivalent to the dynamics of constant tension strings in a Minkowski spacetime. We provide an estimate for the emission of gravitational waves from string loops. Contrary to the standard case, the resulting spectrum is markedly non-flat and has a characteristic falloff at frequencies below the peak one. The peak frequency is defined by the underlying model and lies in the range accessible by the future detectors for very weak couplings involved.

   hep-phastro-ph.COgr-qcJCAP(2022)·27 citations
2. 02*

   Transverse Lambda production at the future Electron-Ion Collider

   Zhong-Bo Kang🇺🇸 · John Terry🇺🇸 · Anselm Vossen🇺🇸 · Qinghua Xu🇨🇳 · Jinlong Zhang🇺🇸

   We provide a comprehensive overview of transversely polarized $\Lambda$ production at the future Electron-Ion Collider (EIC). In particular, we study both spontaneous transverse $\Lambda$ polarization as well as the transverse spin transfer within the Transverse Momentum Dependent (TMD) factorization region. To describe spontaneous $\Lambda$ polarization, we consider the contribution from the TMD Polarizing Fragmentation Function (TMD PFF). Similarly, we study the contribution of the transverse spin transfer originating from the transversity TMD Fragmentation Function (TMD FF). We provide projections for the statistical uncertainties in the corresponding spin observables at the future EIC. Using these statistical uncertainties, we characterize the role that the future EIC will play in constraining these distributions. We perform an impact study in the semi-inclusive deep inelastic scattering process for spontaneous $\Lambda$ polarization with a proton beam. We find that the projected experimental data leads to a significant decrease in the uncertainties for the $u$ and sea TMD PFFs. Furthermore, to access the impact of the EIC on the transversity TMD FF, we perform the first extraction of the transversity TMD FF from the recent COMPASS data. We compare the statistical uncertainties of the future EIC with the theoretical uncertainties from our extraction and find that the EIC could have a significant role in constraining this distribution. Finally, we also provide projections for both spontaneous $\Lambda$ polarization as well as the transverse spin transfer inside the jets in back-to-back electron-jet production at the EIC.

   hep-phhep-exhep-thnucl-ex+1PRD(2022)·33 citations
3. 03*

   Improved indirect limits on muon EDM

   Yohei Ema🇩🇪 · Ting Gao🇺🇸 · Maxim Pospelov🇺🇸

   Given current discrepancy in muon $g-2$ and future dedicated efforts to measure muon electric dipole moment (EDM) $d_{\mu }$, we assess the indirect constraints imposed on $d_{\mu }$ by the EDM measurements performed with heavy atoms and molecules. We notice that the dominant muon EDM effect arises via the muon-loop induced "light-by-light" $CP$-odd amplitude $\propto \mathbf{B}{\mathbf{E}}^3$, and in the vicinity of a large nucleus the corresponding parameter of expansion can be significant, $e{E}_{\mathrm{nucl}}/m_{\mu }^2\sim 0.04$. We compute the $d_{\mu }$-induced Schiff moment of the ${}^{199}$Hg nucleus, and the linear combination of $d_e$ and semileptonic $C_S$ operator (dominant in this case) that determine the $CP$-odd effects in ThO molecule. The results, $d_{\mu }{(}^{199}\mathrm{Hg})<6\times 10^{-20}e$cm and $d_{\mu }(\mathrm{ThO})<2\times 10^{-20}e$cm, constitute approximately three- and nine-fold improvements over the limits on $d_{\mu }$ extracted from the BNL muon beam experiment.

   hep-phPRL(2022)·37 citations
4. 04*

   Proton and neutron form factors from deformed gravity/gauge duality

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

   In this work, we study the electric and magnetic Sachs form factors for proton and neutron by using a deformed gravity/gauge model. We describe holographically baryons as well as gauge bosons which are ruled by the parameters $k_B$ and $k_{\gamma }$, associated with confinement and kinematical energy scales, respectively. Then, we construct the interaction action and calculate the electric and magnetic form factors for the proton and the neutron, and their electromagnetic sizes. The obtained results are compatible with those found in the literature from experimental and theoretical data.

   hep-phhep-thPLB(2021)·15 citations
5. 05*

   Probing the $hc\bar{c}$ coupling at a Future Circular Collider in the electron-hadron mode

   J. Hernández-Sánchez🇲🇽 · C. G. Honorato🇲🇽 · S. Moretti🇬🇧

   We study the production of a neutral Higgs boson at a Future Circular Collider in the electron-hadron mode (FCC-eh) through the leading process $e^{-}p\to {\nu }_{e}hq$ assuming the decay channel $h\to c\bar{c}$, where $h$ is the Standard Model (SM)-like state discovered at the Large Hadron Collider (LHC). This process is studied in the context of a 2-Higgs Doublet Model Type III (2HDM-III) embedding a four-zero texture in the Yukawa matrices and a general Higgs potential, where both Higgs doublets are coupled with up- and down-type fermions. Flavour Changing Neutral Currents (FCNCs) are well controlled by this approach through the adoption of a suitable texture once flavour physics constraints are taken in account. Considering the parameter space where the signal is enhanced and in agreement with both experimental data and theoretical conditions, we analyse the aforementioned signal by taking into account the most important SM backgrounds, separating $c$-jets from light-flavour and gluon ones as well as $b$-jets by means of efficient flavour tagging. We find that the $hc\bar{c}$ coupling strength can be accessed with good significance after a luminosity of $1$ ab${}^{-1}$ for a 50 TeV proton beam and a 60 GeV electron one, the latter with a 80\% (longitudinal) polarisation.

   hep-phhep-exEPJC(2023)·2 citations
6. 06*

   Coloured gravitational instantons, the strong CP problem and the companion axion solution

   Zhe Chen🇦🇺 · Archil Kobakhidze🇦🇺

   Quantum gravity introduces a new source of the combined parity (CP) violation in gauge theories. We argue that this new CP violation gets bundled with the strong CP violation through the coloured gravitational instantons. Consequently, the standard axion solution to the strong CP problem is compromised. Further, we argue that the ultimate solution to the strong CP problem must involve at least one additional axion particle.

   hep-phhep-thEPJC(2022)·19 citations
7. 07*

   Low scale trinification symmetry through effects of dimension-5 operators in $E_6$ grand unified theory with and without supersymmetry

   Chandini Dash🇮🇳 · Snigdha Mishra🇮🇳

   We examine $E_6$ GUT models (both SUSY and non-SUSY) with D-parity violating intermediate trinification symmetry $\left(SU(3{)}_C\otimes SU(3{)}_L\otimes SU(3{)}_R\right)(g_{3L}\ne g_{3R})$ where the D-parity breaking is achieved by quantum gravity effect through dimension-5 operators. Inclusion of the gravitational effect significantly lowers the intermediate scale, being as low as $10$ TeV. However with a given choice of the intermediate mass $M_I$, the gauge unification mass $M_U$ as well as the GUT coupling constant are unaffected by the effects. The predicted value of $M_U$ is shown to be compatible with the accessible limit of the proton lifetime in presence of additional particles i.e. color octet scalars like $(8,2,\frac{1}{2})$ or $(8,1,0)$ and electroweak triplet fermion $(1,3,0)$ at the lower scales. The presence of color octet scalar with mass of the order of TeV may suppress the production of the Higgs boson through gluon fusion. The $SU(2{)}_L$ triplet fermion may behave like a stable dark matter. With reference to cosmological issue, it is expected that no strings or walls bounded by strings associated with D are generated, since the discrete D-parity is broken at the GUT scale.

   hep-ph0 citations
8. 08*

   Light-cone distribution amplitudes of light mesons with QED effects

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

   We discuss the generalization of the leading-twist light-cone distribution amplitude for light mesons including QED effects. This generalization was introduced to describe virtual collinear photon exchanges above the strong-interaction scale ${\Lambda }_{\mathrm{QCD}}$ in the factorization of QED effects in non-leptonic $B$-meson decays. In this paper we study the renormalization group evolution of this non-perturbative function. For charged mesons, in particular, this exhibits qualitative differences with respect to the well-known scale evolution in QCD only, especially regarding the endpoint-behaviour. We analytically solve the evolution equation to first order in the electromagnetic coupling ${\alpha }_{\mathrm{em}}$, which resums large logarithms in QCD on top of a fixed-order expansion in ${\alpha }_{\mathrm{em}}$. We further provide numerical estimates for QED corrections to Gegenbauer coefficients as well as inverse moments relevant to (QED-generalized) factorization theorems for hard exclusive processes.

   hep-phJHEP(2021)·26 citations
9. 09*

   Chiral dynamics with confinement versus the standard chiral theory

   Yu. A. Simonov🇷🇺

   Chiral dynamics is investigated using the chiral confining Lagrangian (CCL), previously derived from QCD with confinement interaction. Based on the calculations of the quark condensate, which is defined entirely by confinement in the zero quark mass limit, one can assert that chiral symmetry breaking occurs not spontaneously but is predetermined by confinement. The expansion of the CCL provides the GMOR relations and the effective chiral Lagrangian, which is used to provide the masses and decay constants of all chiral mesons, including $\eta ,{\eta }^{\prime }$. For the latter one needs to define a non-chiral component due to confinement, while the orthogonality condition defines the wave functions and the eigenvalues. The resulting masses and decay constants of all chiral mesons are obtained in good agreement with experimental and lattice data.

   hep-phhep-latInt.J.Mod.Phys.A(2021)·3 citations
10. 10*

    Connecting Primordial Black Hole to boosted sub-GeV Dark Matter through neutrino

    Wei Chao🇨🇳 · Tong Li🇨🇳 · Jiajun Liao🇨🇳

    The explorations of alternative dark matter (DM) candidates beyond WIMP motivated primordial black holes (PBHs) or sub-GeV DM particle in the Milky Way. Neutrinos from PBH evaporation at the present times play as a novel medium boosting sub-GeV DM and leaving signatures in the terrestrial experiments. We explore the boosted DM by the neutrino flux from PBH evaporation (PBH$\nu$BDM) so as to connect the macroscopic PBHs to sub-GeV DM particle. We consider this PBH$\nu$BDM scenario to interpret the XENON1T keV excess. The projected bounds on the sub-GeV DM-electron scattering cross section and the fraction of DM composed of PBHs $f_{\mathrm{PBH}}$ are imposed for future experiments.

    hep-phhep-ex34 citations
11. 11*

    Leptonic Operators for Cabbibo Angle Anomaly with SMEFT RG Evolution

    Ashutosh Kumar Alok🇮🇳 · Amol Dighe🇮🇳 · Shireen Gangal🇫🇷 · Jacky Kumar🇩🇪

    The measurements of the Cabibbo--Kobayashi--Maskawa (CKM) elements can be contaminated by new-physics effects. We point out that purely leptonic operators at the high scale can influence semileptonic $K$ decays and nuclear beta decay through renormalization group (RG) running, and hence can influence the measurements of $V_{us}$. Interestingly, through this mechanism, a single six-dimensional effective operator $O_{\ell \ell }$ at the high scale can alleviate the tension due to the Cabibbo angle anomaly, by generating the desired operators at the low scale through RG running. When generated as a result of a $Z^{\prime }$ model, the non-universal leptonic couplings of this operator can also contribute to the lepton flavor universality violating ratios such as $R_{K^{(\ast )}}$, which would act as stringent constraints on such scenarios. By performing a global fit of the $Z^{\prime }$ model, we find that it is essential to have non-universal couplings of such a $Z^{\prime }$ boson to all three generations of leptons.

    hep-phhep-exPRD(2023)·18 citations
12. 12*

    General helicity formalism for two-hadron production in $e^{+}{e}^{-}$ annihilation within a TMD approach

    Umberto D'Alesio🇮🇹 · Francesco Murgia🇮🇹 · Marco Zaccheddu🇮🇹

    We present the complete leading-order results for the azimuthal dependences and polarization observables in $e^{+}{e}^{-}\to h_1{h}_2+X$ processes, where the two hadrons are produced almost back-to-back, within a transverse momentum dependent (TMD) factorization scheme. We consider spinless (or unpolarized) and spin-1/2 hadron production and give the full set of the corresponding quark and gluon TMD fragmentation functions (TMD-FFs). By adopting the helicity formalism, which allows for a more direct probabilistic interpretation, single- and double-polarization cases are discussed in detail. Simplified expressions, useful for phenomenological analyses, are obtained by assuming a factorized Gaussian-like dependence on intrinsic transverse momenta for the TMD-FFs.

    hep-phJHEP(2021)·24 citations
13. 13*

    Magic mixing angles for doubly heavy baryons

    Takayuki Matsuki🇯🇵 · Dian-Yong Chen🇨🇳 · Xiang Liu🇨🇳 · Qi-Fang Lü🇨🇳

    We study the so-called magic mixing angles for doubly heavy baryons. Defining that a magic mixing angle rotates states with definite ${}^{2S+1}(l_{\lambda }{)}_J$ to make them heavy-quark symmetric states, we derive the magic mixing angle only in the case $L_{\rho }=0$ between the heavy quark symmetric states with quantum numbers $\left(J,j_{\ell }\right)$ and the states with $\left(J,s_q+j_{\rho }\right)=\left(J,{\{}^4{l}_{\lambda }{/}^2{l}_{\lambda }\}\right)$ for a doubly heavy baryon in the standard $\rho -\lambda$ configuration, where ${\vec{j}}_{\ell }={\vec{l}}_{\lambda }+{\vec{s}}_q$, ${\vec{s}}_{\rho }={\vec{s}}_{Q1}+{\vec{s}}_{Q2}$, and ${\vec{j}}_{\rho }={\vec{s}}_{\rho }+{\vec{L}}_{\rho }$. We discuss how this mixing angle affects model building for a doubly heavy baryon.

    hep-phhep-exnucl-thNucl.Phys.Rev.(2021)·2 citations
14. 14*

    Analysis of the vector hidden-charm tetraquark states without explicit P-waves via the QCD sum rules

    Zhi-Gang Wang🇨🇳

    In the present work, we adopt the scalar, pseudoscalar, vector, axialvector and tensor (anti)diquark operators as the elementary building blocks to construct vector and tensor local four-quark currents without introducing explicit P-waves, and explore the mass spectrum of the vector hidden-charm tetraquark states via the QCD sum rules comprehensively, and revisit the interpretations of the existing $Y$ states in the scenario of vector tetraquark states. We resort to the energy scale formula to enhance the pole contributions and improve the convergent behaviors of the operator product expansion, and we should bear in mind that the predictions are rather sensitive to the particular energy scales which obey the uniform/same constraint. The predicted vector hidden-charm tetraquark states can be confronted to the experimental data in the future.

    hep-phNPB(2021)·26 citations
15. 15*

    CJ15 global PDF analysis with new electroweak data from the STAR and SeaQuest experiments

    Sanghwa Park🇺🇸 · Alberto Accardi🇺🇸 · Xiaoxian Jing🇺🇸 · J.F. Owens🇺🇸

    We present updates to a recent CTEQ-Jefferson Lab (CJ) global analysis of parton distribution functions with a new set of electroweak data that provide unique access to quark flavor separation in the proton. In particular, recent $W$ and $Z$ boson measurements from the STAR experiment at RHIC put additional constraints on light quarks and antiquarks near the valence regime. The new measurement of the Drell-Yan lepton pair production ratio in $p+p$ and $p+d$ collisions by the SeaQuest experiment at Fermilab extends the large-$x$ coverage of the previous E866 experiment and sheds new light on the light antiquarks distribution. In this report, the impact of these new data sets on parton distribution functions will be presented with emphasis given to the flavor asymmetry of the light antiquark sea at large values of the parton momentum $x$.

    hep-phSciPost Phys.Proc.(2023)·9 citations
16. 16*

    Majorana Neutrinos, Exceptional Jordan Algebra, and Mass Ratios for Charged Fermions

    Vivan Bhatt🇮🇳 · Rajrupa Mondal🇮🇳 · Vatsalya Vaibhav🇮🇳 · Tejinder P. Singh🇮🇳

    We provide theoretical evidence that the neutrino is a Majorana fermion. This evidence comes from assuming that the standard model and beyond-standard-model physics can be described through division algebras, coupled to a quantum dynamics. We use the division algebras scheme to derive mass ratios for the standard model charged fermions of three generations. The predicted ratios agree well with the observed values if the neutrino is assumed to be Majorana. However, the theoretically calculated ratios completely disagree with known values if the neutrino is taken to be a Dirac particle. Towards the end of the article we discuss prospects for unification of the standard model with gravitation if the assumed symmetry group of the theory is $E_6$, and if it is assumed that space-time is an 8D octonionic space-time, with 4D Minkowski space-time being an emergent approximation. Remarkably, we find evidence that the precursor of classical gravitation, described by the symmetry $SU(3{)}_{grav}\times SU(2{)}_R\times U(1{)}_{grav}$ is the right-handed counterpart of the standard model $SU(3{)}_{color}\times SU(2{)}_L\times U(1{)}_Y$.

    hep-phJ.Phys.G(2022)·24 citations
17. 17*

    PineAPPL: NLO EW corrections for PDF processes

    Christopher Schwan🇮🇹

    Modern parton distribution function (PDF) determinations either neglect higher-order corrections in the electroweak (EW) coupling or implement them approximately for a subset of PDF processes. We present a new tool, PineAPPL, which supports perturbative correction in arbitrary powers of the EW and strong coupling constant, and stores theoretical predictions independently of the used PDFs in so-called interpolation grids. These are the foundation of any PDF determination, and will allow us to perform a PDF fit taking into account EW corrections for all processes consistently. Apart from PDF determinations PineAPPL can also be used in precision phenomenology to study the impact of different choices of PDF sets, without rerunning the time-consuming computation. As an application of this tool we show Drell-Yan (DY) lepton-pair production were larger effects of NLO EW corrections can be seen that will potentially influence the PDF fit and comment about which observables are particularly suited and NLO EW PDF fit and which are not.

    hep-phSciPost Phys.Proc.(2022)·8 citations
18. 18*

    A cosmologically consistent millicharged dark matter solution to the EDGES anomaly of possible string theory origin

    Amin Aboubrahim🇩🇪 · Pran Nath🇺🇸 · Zhu-Yao Wang🇺🇸

    Analysis of EDGES data shows an absorption signal of the redshifted 21-cm line of atomic hydrogen at $z\sim 17$ which is stronger than expected from the standard $\Lambda$CDM model. The absorption signal interpreted as brightness temperature $T_{21}$ of the 21-cm line gives an amplitude of $-$500${}_{-500}^{+200}$ mK at 99\% C.L. which is a 3.8$\sigma$ deviation from what the standard $\Lambda$CDM cosmology gives. We present a particle physics model for the baryon cooling where a fraction of the dark matter resides in the hidden sector with a $U(1)$ gauge symmetry and a Stueckelberg mechanism operates mixing the visible and the hidden sectors with the hidden sector consisting of dark Dirac fermions and dark photons. The Stueckelberg mass mixing mechanism automatically generates a millicharge for the hidden sector dark fermions providing a theoretical basis for using millicharged dark matter to produce the desired cooling of baryons seen by EDGES by scattering from millicharged dark matter. We compute the relic density of the millicharged dark matter by solving a set of coupled equations for the dark fermion and dark photon yields and for the temperature ratio of the hidden sector and the visible sector heat baths. For the analysis of baryon cooling, we analyze the evolution equations for the temperatures of baryons and millicharged dark matter as a function of the redshift. We exhibit regions of the parameter space which allow consistency with the EDGES data. We note that the Stueckelberg mechanism arises naturally in strings and the existence of a millicharge would point to its string origin.

    hep-phJHEP(2021)·34 citations
19. 19*

    Global QCD Analysis of Pion Parton Distributions with Threshold Resummation

    P. C. Barry🇺🇸 · Chueng-Ryong Ji🇺🇸 · N. Sato🇺🇸 · W. Melnitchouk🇺🇸

    We perform the first global QCD analysis of pion valence, sea quark, and gluon distributions within a Bayesian Monte Carlo framework with threshold resummation on Drell-Yan cross sections at next-to-leading log accuracy. Exploring various treatments of resummation, we find that the large-$x$ asymptotics of the valence quark distribution $\sim (1-x{)}^{{\beta }_v}$ can differ significantly, with ${\beta }_v$ ranging from $\approx 1$ to $>2.5$ at the input scale. Regardless of the specific implementation, however, the resummation induced redistribution of the momentum between valence quarks and gluons boosts the total momentum carried by gluons to $\approx 40\%$, increasing the gluon contribution to the pion mass to $\approx 40$ MeV.

    hep-phhep-exhep-latnucl-thPRL(2021)·123 citations
20. 20*

    Relations between strong decay widths of the $P_c$ pentaquarks in the SU(4) flavor-spin model

    Fl. Stancu🇧🇪

    In a previous work we have studied the isospin 1/2 lowest positive and negative parity states of the pentaquark $uudc\overline{c}$, in a constituent quark model with a linear confinement and an SU(4) flavor-spin hyperfine interaction and we compared the results with the $P_c^{+}(4312)$, $P_c^{+}(4440)$ and $P_c^{+}(4457)$ pentaquarks observed at LHCb in 2019. Here we extend the previous work by calculating ratios of decay rates of the $P_c$ pentaquarks to $J/\Psi$ and ${\eta }_c$ and similarly the ratio of decay rates to ${\Lambda }_c{\bar{D}}^{\ast }$ and ${\Lambda }_c\bar{D}$. Our predictions are based on the SU(4)$\times$SU(2) structure of compact pentaquarks.

    hep-phhep-exnucl-thPRD(2021)·9 citations
21. 21*

    Gravitational waves from bubble walls

    Ariel Megevand🇦🇷 · Federico Agustin Membiela🇦🇷

    We present a general method for computing the gravitational radiation arising from the motion of bubble walls or thin fluid shells in cosmological phase transitions. We discuss the application of this method to different wall kinematics. In particular, we derive general expressions for the bubble collision mechanism in the envelope approximation and the so-called bulk flow model, and we also consider deformations from the spherical bubble shape. We calculate the gravitational wave spectrum for a specific model of deformations on a definite size scale, which gives a peak away from that of the bubble collision mechanism.

    ↳ astro-ph.COgr-qchep-phJCAP(2021)·16 citations
22. 22*

    Probing the environments surrounding ultrahigh energy cosmic ray accelerators and their implications for astrophysical neutrinos

    Marco Stein Muzio🇺🇸 · Glennys R. Farrar🇺🇸 · Michael Unger🇩🇪

    We explore inferences on ultrahigh energy cosmic ray (UHECR) source environments -- constrained by the spectrum and composition of UHECRs and non-observation of extremely high energy neutrinos -- and their implications for the observed high energy astrophysical neutrino spectrum. We find acceleration mechanisms producing power-law CR spectra~$\propto E^{-2}$ are compatible with UHECR data, if CRs at high rigidities are in the quasi-ballistic diffusion regime as they escape their source environment. Both gas-dominated and photon-dominated source environments are able to account for UHECR observations, however photon-dominated sources give a better fit. Additionally, gas-dominated sources are in tension with current neutrino constraints. Accurate measurement of the neutrino flux at $\sim 10$ PeV will provide crucial information on the viability of gas-dominated sources, as well as whether diffusive shock acceleration is consistent with UHECR observations. We also show that UHECR sources are able to give a good fit to the high energy portion of the astrophysical neutrino spectrum, above $\sim$ PeV. This common origin of UHECRs and high energy astrophysical neutrinos is natural if air shower data is interpreted with the Sibyll2.3c hadronic interaction model, which gives the best-fit to UHECRs and astrophysical neutrinos in the same part of parameter space, but not for EPOS-LHC.

    ↳ astro-ph.HEastro-ph.COhep-phPRD(2022)·65 citations
23. 23*

    Strange Baryons in Nuclei and Neutron Stars

    Laura Tolos🇪🇸

    In this contribution we review the dynamics of hyperons with nucleons and nuclear matter, paying a special attention to hypernuclei. We also discuss the presence of hyperons in the inner core of neutron stars and the consequences for the structure of these compact stars.

    ↳ nucl-thastro-ph.HEhep-exhep-phEPJ Web Conf.(2022)·1 citation
24. 24*

    Gravitational Waves and Primordial Black Holes from Supersymmetric Hybrid Inflation

    Vassilis C. Spanos🇬🇷 · Ioanna D. Stamou🇬🇷

    We study the effect of supergravity corrections due to a linear and a bilinear term in the Kähler potential, in the context of a supersymmetric hybrid inflation model. By appropriate choice of the parameters associated to these terms, we are able to satisfy the main cosmological constraints for the spectral index $n_s$ and the tensor-to-scalar ratio $r$. In addition, this model predicts primordial black hole abundance enough to account for the whole dark matter of the Universe and gravitational wave spectra within the reach of future detection experiments. The predictions of the model can be made compatible to the NANOGrav reported signal, at the cost of significantly lower primordial black hole abundance.

    ↳ astro-ph.COgr-qchep-phhep-thPRD(2021)·38 citations
25. 25*

    On the Mechanism of Temperature Variations in the Average Energy of Muons at Large Depths

    N.Yu. Agafonova🇷🇺 · A.S. Malgin🇷🇺

    Sources of seasonal temperature variations in the average energy of the muon flux detected in the LVD experiment have been discussed. It has been shown that variations are due to the processes of generation of muons in upper layers of the atmosphere and the passage of muons through a thick rock layer.

    ↳ hep-exhep-phphysics.ins-detJ.Exp.Theor.Phys.(2021)·3 citations
26. 26*

    Pre-burst events of gamma-ray bursts with light speed variation

    Jie Zhu🇨🇳 · Bo-Qiang Ma🇨🇳

    Previous researches on high-energy photon events from gamma-ray bursts~(GRBs) suggest a light speed variation $v(E)=c(1-E/E_{\mathrm{LV}})$ with $E_{\mathrm{LV}}=3.6\times 10^{17}\mathrm{GeV}$, together with a pre-burst scenario that hight-energy photons come out about 10 seconds earlier than low-energy photons at the GRB source. However, in the Lorentz invariance violating scenario with an energy dependent light speed considered here, high-energy photons travel slower than low-energy photons due to the light speed variation, so that they are usually detected after low-energy photons in observed GRB data. Here we find four high-energy photon events which were observed earlier than low-energy photons from Fermi Gamma-ray Space Telescope~(FGST), and analysis on these photon events supports the pre-burst scenario of high energy photons from GRBs and the energy dependence of light speed listed above.

    ↳ astro-ph.HEgr-qchep-phPLB(2021)·43 citations
27. 27*

    Gravitational Causality and the Self-Stress of Photons

    Brando Bellazzini🇫🇷 · Giulia Isabella🇫🇷 · Matthew Lewandowski🇺🇸 · Francesco Sgarlata🇺🇸

    We study causality in gravitational systems beyond the classical limit. Using on-shell methods, we consider the one-loop corrections from charged particles to the photon energy-momentum tensor - the self-stress - that controls the quantum interaction between two on-shell photons and one off-shell graviton. The self-stress determines in turn the phase shift and time delay in the scattering of photons against a spectator particle of any spin in the eikonal regime. We show that the sign of the $\beta$-function associated to the running gauge coupling is related to the sign of time delay at small impact parameter. Our results show that, at first post-Minkowskian order, asymptotic causality, where the time delay experienced by any particle must be positive, is respected quantum mechanically. Contrasted with asymptotic causality, we explore a local notion of causality, where the time delay is longer than the one of gravitons, which is seemingly violated by quantum effects.

    ↳ hep-thhep-phJHEP(2022)·51 citations
28. 28*

    Scale and Weyl Invariance in Einstein-Cartan Gravity

    Georgios K. Karananas🇩🇪 · Mikhail Shaposhnikov🇨🇭 · Andrey Shkerin🇺🇸 · Sebastian Zell🇨🇭

    We show how Einstein-Cartan gravity can accommodate both global scale and local scale (Weyl) invariance. To this end, we construct a wide class of models with nonpropagaing torsion and a nonminimally coupled scalar field. In phenomenological applications the scalar field is associated with the Higgs boson. For global scale invariance, an additional field -- dilaton -- is needed to make the theory phenomenologically viable. In the case of the Weyl symmetry, the dilaton is spurious and the theory reduces to a sub-class of one-field models. In both scenarios of scale invariance, we derive an equivalent metric theory and discuss possible implications for phenomenology.

    ↳ hep-thgr-qchep-phPRD(2021)·49 citations
29. 29*

    The impact of transverse Slavnov-Taylor identities on dynamical chiral symmetry breaking

    Luis Albino🇧🇷 · Adnan Bashir🇲🇽 · Bruno El-Bennich🇧🇷 · Eduardo Rojas🇨🇴 · Fernando E. Serna🇧🇷 · Roberto Correa da Silveira🇧🇷

    We extend earlier studies of transverse Ward-Fradkin-Green-Takahashi identities in QED, their usefulness to constrain the transverse fermion-boson vertex and their importance for multiplicative renormalizability, to the equivalent gauge identities in QCD. To this end, we consider transverse Slavnov-Taylor identities that constrain the transverse quark-gluon vertex and derive its eight associated scalar form factors. The complete vertex can be expressed in terms of the quark's mass and wave-renormalization functions, the ghost-dressing function, the quark-ghost scattering amplitude and a set of eight form factors. The latter parametrize the hitherto unknown nonlocal tensor structure in the transverse Slavnov-Taylor identity which arises from the Fourier transform of a four-point function involving a Wilson line in coordinate space. We determine the functional form of these eight form factors with the constraints provided by the Bashir-Bermudez vertex and study the effects of this novel vertex on the quark in the Dyson-Schwinger equation using lattice QCD input for the gluon and ghost propagators. We observe significant dynamical chiral symmetry breaking and a mass gap that leads to a constituent mass of the order of 500 MeV for the light quarks. The flavor dependence of the mass and wave-renormalization functions as well as their analytic behavior on the complex momentum plane is studied and as an application we calculate the quark condensate and the pion's weak decay constant in the chiral limit. Both are in very good agreement with their reference values.

    ↳ nucl-thhep-lathep-phJHEP(2021)·24 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.