Mon·Jul 24, 2023Monday·July 24, 2023

1. 01*

   Synchronization effects on rest frame energy and momentum densities in the proton

   Adam Freese🇺🇸 · Gerald A. Miller🇺🇸

   We obtain two-dimensional relativistic densities and currents of energy and momentum in a proton at rest. These densities are obtained at surfaces of fixed light front time, which physically corresponds to using an alternative synchronization convention. Mathematically, this is done using tilted light front coordinates, which consist of light front time and ordinary spatial coordinates. In this coordinate system, all sixteen components of the energy-momentum tensor obtain clear physical interpretations, and the nine Galilean components reproduce results from standard light front coordinates. We find angular modulations in several densities that are absent in the corresponding instant form results, which are explained as optical effects arising from using fixed light front time when motion is present within the target. Additionally, transversely-polarized spin-half targets exhibit an energy dipole moment -- which evaluates to $-1/4$ for all targets if the Belinfante EMT is used, but which is target dependent and vanishes for pointlike fermions if the asymmetric EMT is instead used.

   hep-phnucl-thPRD(2023)·16 citations
2. 02*

   Spectra of axions emitted from main sequence stars

   Ngan H. Nguyen🇺🇸 · Erwin H. Tanin🇺🇸 · Marc Kamionkowski🇺🇸

   We compute the detailed energy spectra of axions with two-photon coupling produced in stellar cores over a wide range of stellar masses. We focus on main sequence stars and base our calculations on the stellar interior profiles from MESA, for which we provide simple fits in an appendix. The obtained stellar axion spectra, combined with recent models of star formation history and stellar initial mass function, enable us to estimate the properties of the diffuse axion background sourced by all the stars in the universe. The fluxes of this stellar axion background and its decay photons are subdominant to but can in principle be disentangled from those expected from the Sun and the early universe based on their different spectral and spatial profiles.

   hep-phastro-ph.COastro-ph.HEastro-ph.SRJCAP(2023)·25 citations
3. 03*

   On the momentum broadening of in-medium jet evolution using a light-front Hamiltonian approach

   Meijian Li🇪🇸 · Tuomas Lappi🇫🇮 · Xingbo Zhao🇨🇳 · Carlos A. Salgado🇪🇸

   We have developed a non-perturbative light-front Hamiltonian formalism to simulate the real-time evolution of a quark state in a SU(3) colored medium, with a series of works. In this proceeding article, we focus on the transverse momentum broadening of an in-medium quark jet. We perform the numerical simulation of the quark jet evolution in the $|q⟩+|qg⟩$ Fock space at various medium densities. By analyzing the resulting jet light-front wavefunction, we extract the gluon emission rate and the non-eikonal quenching parameter. Additionally, we provide the analytical derivation of the eikonal expectation value of the quark-gluon state's transverse momentum for any color configuration and arbitrary spatial distribution. This study can help understand jet momentum broadening beyond the eikonal limit.

   hep-phnucl-thPoS(2024)·1 citation
4. 04*

   Strong decays of the $P_c(4312)$ and its isospin cousin via the QCD sum rules

   Xiu-Wu Wang🇨🇳 · Zhi-Gang Wang🇨🇳

   In the present work, considering the conservation of isospin in the strong decays, we investigate the strong decays of the pentaquark molecule candidate $P_c(4312)$ and its possible higher isospin cousin $P_c(4330)$ in the framework of the QCD sum rules. What's more, the pole residue of the $\Delta$ baryon with isospin eigenstate $|I{I}_3⟩=|\frac{3}{2}\frac{1}{2}⟩$ is obtained. If the possible pentaquark molecule candidate $P_c(4330)$ could be testified in the future experiment, it would shed light on interpretations of the $P_c$ states.

   hep-phCPC(2024)·5 citations
5. 05*

   Complementarity of $\mu$TRISTAN and Belle II in searches for charged-lepton flavour violation

   Gabriela Lichtenstein🇦🇺 · Michael A. Schmidt🇦🇺 · German Valencia🇦🇺 · Raymond R. Volkas🇦🇺

   We analyse the potential of the proposed ${\mu }^{+}{\mu }^{+}$ and ${\mu }^{+}{e}^{-}$ collider $\mu$TRISTAN to complement the searches for charged-lepton flavour-violation (CLFV) that can be carried out by Belle II. $\mu$TRISTAN offers the possibility of directly producing and studying new resonances that could mediate CLFV for a certain range of masses. In addition, we find that it can produce competitive bounds to those from Belle II for cases where the new resonance lies beyond direct reach. We illustrate these points with three $Z_3$ "lepton triality" models, where we also find an example that can only be probed by $\mu$TRISTAN. These three models feature doubly-charged scalars, denoted $k_{1,2,3}$ respectively, that induce both CLFV and flavour-conserving processes. Tree-level $k_1$ exchange induces the CLFV scattering process ${\mu }^{+}{e}^{-}\to e^{+}{\tau }^{-}$, while $k_2$ interactions induce ${\mu }^{+}{\mu }^{+}\to {\tau }^{+}{e}^{+}$, ${\mu }^{+}{e}^{-}\to {\tau }^{+}{\mu }^{-}$ and make a non-SM contribution to the flavour-conserving scattering ${\mu }^{+}{\mu }^{+}\to {\mu }^{+}{\mu }^{+}$. The $k_3$ model has a non-SM contribution to the flavour-conserving process ${\mu }^{+}{e}^{-}\to {\mu }^{+}{e}^{-}$. Other scattering processes involving $k_1$, $k_2$ or $k_3$ are not relevant for $\mu$TRISTAN and outside the scope of our analysis. We quantify the sensitivity of $\mu$TRISTAN for each of these processes. For the $k_1$ and $k_2$ cases we compare the $\mu$TRISTAN reach to the expected sensitivity of Belle II to the crossing symmetry related CLFV $\tau$ decays.

   hep-phPLB(2023)·25 citations
6. 06*

   Stability of neutrino oscillation parameters at low energy scale with the variations of SUSY breaking scale under Renormalisation Group Equations

   Kh. Helensana Devi🇮🇳 · K. Sashikanta Sngh🇮🇳 · N. Nimai Singh🇮🇳

   We discuss the stability of the neutrino oscillation parameters at low energy scale including self-complementarity (SC) relations among mixing angles under radiative corrections with the variation of SUSY breaking scale ($m_s$) in both normal and inverted hierarchical cases. We observe that the neutrino oscillation parameters including the SC relation maintains stability at the electroweak scale within $1\sigma$ range of the latest global fit data. NH case maintains more stability than IH case. All the numerical values related to the absolute neutrino masses viz., $\Sigma |m_i|$, $m_{\beta }$ and $m_{\beta \beta }$ are found to lie below the observational upper bound.

   hep-ph0 citations
7. 07*

   The role of the pion in the lineshape of the $X(3872)$

   Angelo Esposito🇮🇹 · Davide Germani🇮🇹 · Alfredo Glioti🇫🇷 · Antonio D. Polosa🇮🇹 · Riccardo Rattazzi🇨🇭 · Michele Tarquini🇺🇸

   We determine the contribution of long-range pion interactions to the $X(3872)$ dynamics, assuming it is a loosely bound $D^0{\bar{D}}^{\ast 0}$ molecule. Our result is based on the distorted wave Born approximation in non-relativistic quantum mechanics. Despite their long-range nature, we find that pion interactions cannot produce a large and negative effective range. Nonetheless, they introduce imaginary parts. In particular, they contribute to the total decay width of the $X(3872)$ with a term associated with, but not precisely corresponding to, the $D^{\ast }$ width. Our approach can also be applied to the recently discovered $T_{cc}^{+}$ states.

   hep-phnucl-thPLB(2023)·20 citations
8. 08*

   Quarkonium spectroscopy of the linear plus modified Yukawa potential

   Kaushal R Purohit🇮🇳 · Pooja Jakhad🇮🇳 · Ajay Kumar Rai🇮🇳

   In this article, the linear plus modified Yukawa potential (LIMYP) is used as the quark antiquark interaction potential for the approximate analytical bound state solution of the Klein Gordon equation in three-dimensional space. The energy eigenvalues and associated wavefunction are obtained by solving the Klein Gordon equation analytically using the Nikiforov Uvarov (NU) method. The mass spectra of heavy mesons such as charmonium $(c\bar{c})$, bottomonium $(b\bar{b})$, and $b\bar{c}$ for various quantum states are obtained using the energy spectra expression. In comparison to experimental data, graphical modification of acquired mass spectra of heavy mesons with the parameter employed in the energy equation and the current potential provides good results.

   hep-phPhys.Scripta(2022)·23 citations
9. 09*

   Nano-Hertz gravitational waves from collapsing domain walls associated with freeze-in dark matter in light of pulsar timing array observations

   Zhao Zhang🇫🇷 · Chengfeng Cai🇨🇳 · Yu-Hang Su🇨🇳 · Shiyu Wang🇨🇳 · Zhao-Huan Yu🇨🇳 · Hong-Hao Zhang🇨🇳

   Evidence for a stochastic gravitational wave background in the nHz frequency band is recently reported by four pulsar timing array collaborations NANOGrav, EPTA, CPTA, and PPTA. It can be interpreted by gravitational waves from collapsing domain walls in the early universe. We assume such domain walls arising from the spontaneous breaking of a $Z_2$ symmetry in a scalar field theory, where a tiny $Z_2$-violating potential is required to make domain walls unstable. We propose that this $Z_2$-violating potential is radiatively induced by a feeble Yukawa coupling between the scalar field and a fermion field, which is also responsible for dark matter production via the freeze-in mechanism. Combining the pulsar timing array data and the observed dark matter relic density, we find that the model parameters can be narrowed down to small ranges.

   hep-phastro-ph.COPRD(2023)·97 citations
10. 10*

    Exploring slicing variables for jet processes

    Luca Buonocore🇨🇭 · Massimiliano Grazzini🇨🇭 · Jürg Haag🇨🇭 · Luca Rottoli🇨🇭 · Chiara Savoini🇨🇭

    We consider the class of inclusive hadron collider processes in which one or more energetic jets are produced, possibly accompanied by colourless particles. We provide a general formulation of a slicing scheme for this class of processes, by identifying the various contributions that need to be computed up to next-to-leading order (NLO) in QCD perturbation theory. We focus on two novel observables, the one-jet resolution variable $\Delta E_t$ and the $n$-jet resolution variable $k_T^{\mathrm{ness}}$, and explicitly compute all the ingredients needed to carry out NLO computations using these variables. We contrast the behaviour of these variables when the slicing parameter becomes small. In the case of $k_T^{\mathrm{ness}}$ we also present results for the hadroproduction of multiple jets.

    hep-phJHEP(2023)·15 citations
11. 11*

    Exploring Solar Neutrino Oscillation Parameters with LSC at Yemilab and JUNO

    Pouya Bakhti🇰🇷 · Meshkat Rajaee🇰🇷 · Seon-Hee Seo🇰🇷 · Seodong Shin🇰🇷

    We investigate the sensitivities of the liquid scintillator counter (LSC) at Yemilab and JUNO to solar neutrino oscillation parameters, focusing on ${\theta }_{12}$ and $\Delta m_{21}^2$. We compare the potential of JUNO with LSC at Yemilab utilizing both reactor and solar data in determining those parameters. We find that the solar neutrino data of LSC at Yemilab is highly sensitive to ${\theta }_{12}$ enabling its determination with exceptional precision. Our study also reveals that if $\Delta m_{21}^2$ is larger, with a value close to the best fit value of KamLAND, JUNO reactor data will have about two times better precision than the reactor LSC at Yemilab. On the other hand, if $\Delta m_{21}^2$ is smaller and closer to the best fit value of solar neutrino experiments, the precision of the reactor LSC at Yemilab will be better than JUNO.

    hep-phhep-exPRD(2024)·3 citations
12. 12*

    Two-pole structures as a universal phenomenon dictated by coupled-channel chiral dynamics

    Jia-Ming Xie🇨🇳 · Jun-Xu Lu🇨🇳 · Li-Sheng Geng🇨🇳 · Bing-Song Zou🇨🇳

    In the past two decades, one of the most puzzling phenomena discovered in hadron physics is that a nominal hadronic state can actually correspond to two poles on the complex energy plane. This phenomenon was first noticed for the $\Lambda (1405)$, then for $K_1(1270)$, and to a lesser extent for $D_0^{\ast }(2300)$. In this Letter, we show explicitly how the two-pole structures emerge from the underlying universal chiral dynamics describing the coupled-channel interactions between heavy matter particles and pseudo Nambu-Goldstone bosons. In particular, the fact that two poles appear in between the two dominant coupled channels can be attributed to the particular form of the leading order chiral potentials of the Weinberg-Tomozawa form. Their lineshapes overlap with each other because the degeneracy of the two coupled channels is only broken by explicit chiral symmetry breaking of higher order. We predict that for light-quark~(pion) masses heavier than their physical values (e.g., about 200 MeV in the $\Lambda (1405)$ case studied), the lower pole becomes a virtual state, which can be easily verified by future lattice QCD simulations. Furthermore, we anticipate similar two-pole structures in other systems, such as the isopin $1/2$ $\bar{K}{\Sigma }_c-\pi {\Xi }_c^{\prime }$ coupled channel, which await for experimental discoveries.

    hep-phhep-exhep-latPRD(2023)·35 citations
13. 13*

    Primordial black holes as dark matter: Interferometric tests of phase transition origin

    Iason Baldes🇫🇷 · María Olalla Olea-Romacho🇫🇷

    We show that primordial black holes - in the observationally allowed mass window with $f_{\mathrm{pbh}}=1$ - formed from late nucleating patches in a first order phase transition imply upcoming gravitational wave interferometers will see a large stochastic background arising from the bubble collisions. As an example, we use a classically scale invariant $B-L$ model, in which the right handed neutrinos explain the neutrino masses and leptogenesis, and the dark matter consists of primordial black holes. The conclusion regarding the gravitational waves is, however, expected to hold model independently for black holes coming from such late nucleating patches.

    hep-phastro-ph.COJHEP(2024)·62 citations
14. 14*

    Signatures of vacuum birefringence in low-power flying focus pulses

    Martin Formanek🇨🇿 · John P. Palastro🇺🇸 · Dillon Ramsey🇺🇸 · Stefan Weber🇨🇿 · Antonino Di Piazza🇩🇪

    Vacuum birefringence produces a differential phase between orthogonally polarized components of a weak electromagnetic probe in the presence of a strong electromagnetic field. Despite representing a hallmark prediction of quantum electrodynamics, vacuum birefringence remains untested in pure light configurations due to the extremely large electromagnetic fields required for a detectable phase difference. Here, we exploit the programmable focal velocity and extended focal range of a flying focus laser pulse to substantially lower the laser power required for detection of vacuum birefringence. In the proposed scheme, a linearly polarized x-ray probe pulse counter-propagates with respect to a flying focus pulse, whose focus moves at the speed of light in the same direction as the x-ray probe. The peak intensity of the flying focus pulse overlaps the probe over millimeter-scale distances and induces a polarization ellipticity on the order of $10^{-10}$, which lies within the detection sensitivity of existing x-ray polarimeters.

    hep-phphysics.opticsPRD(2024)·15 citations
15. 15*

    Electric Dipole Moments as Probes of $B$ Anomaly

    Syuhei Iguro🇩🇪 · Teppei Kitahara🇯🇵

    The measurements of the lepton flavor universality (LFU) in $\mathcal{B}(\bar{B}\to D^{(\ast )}l\bar{\nu })$ indicate a significant deviation from the standard model prediction at a 3-4$\sigma$ level, revealing a violation of the LFU ($R_{D^{(\ast )}}$ anomaly). It is known that the $R_{D^{(\ast )}}$ anomaly can be easily accommodated by an $SU(2{)}_L$-singlet vector leptoquark (LQ) coupled primarily to third-generation fermions, whose existence is further motivated by a partial gauge unification. In general, such a LQ naturally leads to additional $CP$-violating phases in the LQ interactions. In this paper, we point out that the current $R_{D^{(\ast )}}$ anomaly prefers the $CP$-violating interaction although $\mathcal{B}(\bar{B}\to D^{(\ast )}l\bar{\nu })$ are $CP$-conserving observables. The $CP$-violating LQ predicts a substantial size of the bottom-quark electric dipole moment (EDM), the chromo-EDM, and also the tau-lepton EDM. Eventually at low energy, the nucleon and electron EDMs are radiatively induced. Therefore, we conclude that the $R_{D^{(\ast )}}$ anomaly with the $SU(2{)}_L$-singlet vector LQ provides unique predictions: neutron and proton EDMs with opposite signs and a magnitude of $\mathcal{O}(10^{-27})e$cm, and suppressed electron EDM. Furthermore, we show that a similar EDM pattern is predicted in an $SU(2{)}_L$-doublet scalar LQ scenario that can accommodate the $R_{D^{(\ast )}}$ anomaly as well. These EDM signals could serve as crucial indicators in future experiments.

    hep-phhep-exPRD(2024)·8 citations
16. 16*

    Axion Clouds around Neutron Stars

    Dion Noordhuis🇳🇱 · Anirudh Prabhu🇺🇸 · Christoph Weniger🇳🇱 · Samuel J. Witte🇳🇱

    Recent work has shown that axions can be efficiently produced via non-stationary pair plasma discharges in the polar cap region of pulsars. Here, we point out that for axion masses $10^{-9}\mathrm{eV}\lesssim m_a\lesssim 10^{-4}\mathrm{eV}$, a sizable fraction of the sourced axion population will be gravitationally confined to the neutron star. These axions accumulate over astrophysical timescales, thereby forming a dense `axion cloud' around the star. We argue that the existence of such a cloud, with densities reaching and potentially exceeding $\mathcal{O}(10^{22})\mathrm{GeV}\mathrm{c}{\mathrm{m}}^{-3}$, is a generic expectation across a wide range of parameter space. For axion masses $m_a\gtrsim 10^{-7}\mathrm{eV}$, energy is primarily radiated from the axion cloud via resonant axion-photon mixing, generating a number of distinctive signatures that include: a sharp line in the radio spectrum of each pulsar (located at the axion mass, and with an order percent-level width), and transient events arising from the reconfiguration of charge densities in the magnetosphere. While a deeper understanding of the systematic uncertainties in these systems is required, our current estimates suggest that existing radio telescopes could improve sensitivity to the axion-photon coupling by more than an order of magnitude.

    hep-phastro-ph.COPRX(2024)·53 citations
17. 17*

    Axion-Photon Conversion in 3D Media and Astrophysical Plasmas

    J. I. McDonald🇧🇪 · B. Garbrecht🇩🇪 · P. Millington🇬🇧

    With axions now a primary candidate for dark matter, understanding their indirect astrophysical signatures is of paramount importance. Key to this is the production of photons from axions in magnetised astrophysical plasmas. While simple formulae for axion-photon mixing in 1D have been sketched several decades ago, there has recently been renewed interest in robust calculations for this process in arbitrary 3D plasmas. These calculations are vital for understanding, amongst other things, the radio production from axion dark matter conversion in neutron stars, which may lead to indirect axion dark matter detection with current telescopes or future searches, e.g., by the SKA. In this paper, we derive the relevant transport equations in magnetised plasmas. These equations describe both the production and propagation of photons in an arbitrary 3D medium due to the resonant conversion of axions into photons. They also fully incorporate the refraction of photons, and we find no evidence for a conjectured phenomenon of dephasing. Our result is free of divergences that plagued previous calculations, and our kinetic theory description provides a direct link between ray tracing and the production mechanism. These results mark an important step toward solving one of the major open questions concerning indirect searches of axions in recent years, namely how to compute the photon production rate from axions in arbitrary 3D plasmas.

    hep-phastro-ph.COgr-qcJCAP(2023)·33 citations
18. 18*

    The flavor of a light charged Higgs

    Nicolás Bernal🇦🇪 · Marta Losada🇦🇪 · Yosef Nir🇮🇱 · Yogev Shpilman🇮🇱

    The ATLAS Collaboration has recently reported a search for light-charged Higgs in $t\to H^{+}b$ decay, with $H^{+}\to c\bar{b}$. An excess with a local significance of approximately $3\sigma$ is found at $m_{H^{+}}\approx 130$ GeV, with a best-fit value of $\mathrm{BR}(t\to H^{+}b)\times \mathrm{BR}(H^{+}\to c\bar{b})=(1.6\pm 0.6)\times 10^{-3}$. We study the implications of such a hypothetical signal in multi-Higgs doublet models. We take into account constraints from searches for other charged Higgs decays and from flavor-changing neutral current processes. Two Higgs doublet models with flavor structure dictated by natural flavor conservation (NFC), minimal flavor violation (MFV), or the Froggatt-Nielsen (FN) mechanism cannot account for such excess. A three-Higgs doublet model with NFC can account for the signal. The Yukawa couplings of the neutral pseudoscalar $A$ in the down sector, ${\hat{Y}}_A^D$, should be larger by a factor of $4-6$ compared to the corresponding Yukawa couplings of the Higgs $h$, ${\hat{Y}}_h^D$. We further present two minimal scenarios, one in which a single Yukawa coupling in the down sector, $({\hat{Y}}_A^D{)}_{bb}$, gives the only significant contribution, and one in which two Yukawa couplings in the up sector, $({\hat{Y}}_A^U{)}_{tt}$ and $({\hat{Y}}_A^U{)}_{tc}$, give the only significant contributions, and we discuss possible tests of these scenarios.

    hep-phJHEP(2023)·6 citations
19. 19*

    Electron-positron plasma in BBN: damped-dynamic screening

    Christopher Grayson (UArizona)🇺🇸 · Cheng Tao Yang (UArizona)🇺🇸 · Martin Formanek (ELI-Beamlines)🇨🇿 · Johann Rafelski (UArizona)🇺🇸

    We characterize in detail the very dense $e^{-}{e}^{+}\gamma$ plasma present during the Big-Bang Nucleosynthesis (BBN) and explore how it is perturbed electromagnetically by \lq\lq impurities, {\it i.e.\/}, spatially dispersed protons and light nuclei undergoing thermal motion. The internuclear electromagnetic screened potential is obtained (analytically) using the linear response approach, allowing for the dynamic motion of the electromagnetic field sources and the damping effects due to plasma component scattering. We discuss the limits of the linear response method and suggest additional work needed to improve BBN reaction rates in the primordial Universe. Our theoretical methods to describe the potential between charged dust particles align with previous studies on planetary and space dusty plasma and could have significant impact on interpretation of standard cosmological model results.

    ↳ astro-ph.COhep-phnucl-thphysics.plasm-phAnnals Phys.(2023)·13 citations
20. 20*

    Vanishing cycles and analysis of singularities of Feynman diagrams

    Stanislav Srednyak🇺🇸 · Vladimir Khachatryan🇺🇸

    In this work, we analyze vanishing cycles of Feynman loop integrals by means of the Mayer-Vietoris spectral sequence. A complete classification of possible vanishing geometries are obtained. We employ this result for establishing an asymptotic expansion for the loop integrals near their singularity locus, then give explicit formulas for the coefficients of such an expansion. The further development of this framework may potentially lead to exact calculations of one- and two-loop Feynman diagrams, as well as other next-to-leading and higher-order diagrams, in studies of radiative corrections for upcoming lepton-hadron scattering experiments.

    ↳ math-phhep-phhep-thmath.MPMathematics(2025)·2 citations
21. 21*

    Comment on "Horizon-scale tests of gravity theories and fundamental physics from the Event Horizon Telescope image of Sagittarius A*"

    Naoki Tsukamoto🇯🇵

    Vagnozzi et al. constrained the additional parameter of spacetimes with a photon sphere from the observation of the shadow of Sagittarius A* under the assumption that a distance to the Sagittarius A* and its mass parameter was estimated from other observations. They claimed that a Damour-Solodukhin wormhole with an additional parameter $\lambda$ is not an asymptotically-flat spacetime and that they gave the first robust observational constraint on the parameter $\lambda$ of the Damour-Solodukhin wormhole. However, they overlooked the fact that: (A) the Damour-Solodukhin wormhole spacetime is asymptotically flat, (B) the throat of the Damour-Solodukhin wormhole works as an effective photon sphere for $\lambda >\sqrt{2}/2$, and (C) not only a usual mass parameter but also the parameter $\lambda$ contributes the mass of the Damour-Solodukhin wormhole. Because of the overlook (C), we realize that their constraint on the parameter $\lambda$ is invalid. This is because their method corresponds to the following way: They estimated the mass parameter from the other observations under the assumption $\lambda =0$ even though the value of the parameter $\lambda$ strongly affects the determination of the mass parameter, and then, they used the value of the mass parameter to constrain $\lambda$ from the observation of the shadow. We conclude that we should constrain the mass parameter and $\lambda$ from the shadow observation and other observations without the assumption $\lambda =0$.

    ↳ gr-qcastro-ph.HEhep-phhep-thClass.Quant.Grav.(2023)·8 citations
22. 22*

    Quantum phase transition and absence of quadratic divergence in generalized quantum field theories

    Hikaru Kawai🇹🇼 · Kiyoharu Kawana🇰🇷 · Kin-ya Oda🇯🇵 · Kei Yagyu🇯🇵

    In ordinary thermodynamics, around first-order phase transitions, the intensive parameters such as temperature and pressure are automatically fixed to the phase transition point when one controls the extensive parameters such as total volume and total energy. From the microscopic point of view, the extensive parameters are more fundamental than the intensive parameters. Analogously, in conventional quantum field theory (QFT), coupling constants (including masses) in the path integral correspond to intensive parameters in the partition function of the canonical formulation. Therefore, it is natural to expect that in a more fundamental formulation of QFT, coupling constants are dynamically fixed a posteriori, just as the intensive parameter in the micro-canonical formulation. Here, we demonstrate that the automatic tuning of the coupling constants is realized at a quantum-phase-transition point at zero temperature, even when the transition is of higher order, due to the Lorentzian nature of the path integral. This naturally provides a basic foundation for the multi-critical point principle. As a concrete toy model for solving the Higgs hierarchy problem, we study how the mass parameter is fixed in the ${\varphi }^4$ theory at the one-loop level in the micro-canonical or further generalized formulation of QFT. We find that there are two critical points for the renormalized mass: zero and of the order of ultraviolet-cutoff. In the former, the Higgs mass is automatically tuned to be zero and thus its fine-tuning problem is solved. We also show that the quadratic divergence is absent in a more realistic two-scalar model that realizes the dimensional transmutation. Additionally, we explore the possibility of fixing quartic coupling in ${\varphi }^4$ theory and find that it can be fixed to a finite value.

    ↳ hep-thhep-phPRD(2024)·4 citations
23. 23*

    Inflation Based on the Tsallis Entropy

    Zeinab Teimoori🇮🇷 · Kazem Rezazadeh🇮🇷 · Abasat Rostami🇮🇷

    We study the inflationary scenario in the Tsallis entropy-based cosmology. The Friedmann equations in this setup can be derived by using the first law of thermodynamics. To derive the relations of the power spectra of the scalar and tensor perturbations in this setup, we reconstruct an $f(R)$ gravity model which is thermodynamically equivalent to our model in the slow-roll approximation. In this way, we find the inflationary observables, including the scalar spectral index and the tensor-to-scalar ratio in our scenario. Then, we investigate two different potentials in our scenario, including the quadratic potential and the potential associated with the natural inflation in which the inflaton is an axion or a pseudo-Nambu-Goldstone boson. We examine their observational viability in light of the Planck 2018 CMB data. We show that although the results of these potentials are in tension with the observations in the standard inflationary setting, their consistency with the observations can be significantly improved within the setup of the Tsallis entropy-based inflation. Moreover, we place constraints on the parameters of the considered inflationary models by using the current observational data.

    ↳ gr-qchep-phhep-thEPJC(2024)·22 citations
24. 24*

    Probing the nature of electroweak symmetry breaking with Higgs boson pairs in ATLAS

    Bartlomiej Zabinski (on behalf of the ATLAS Collaboration)🇵🇱

    Constraints on the Higgs boson trilinear self-coupling modifier ${\kappa }_{\lambda }$ and non-SM HHVV coupling strength ${\kappa }_{2V}$ are set by combining di-Higgs boson analyses using $b\bar{b}b\bar{b}$, $b\bar{b}{\tau }^{+}{\tau }^{-}$ and $b\bar{b}\gamma \gamma$ decay channels. The data used in these analyses were recorded by the ATLAS detector at the Large Hadron Collider in proton-proton collisions at $\sqrt{s}$ = 13 TeV and corresponding to an integrated luminosity of 126-139 $f{b}^{-1}$. The combination of the di-Higgs analyses sets an upper limit of signal strength ${\mu }_{HH}<$ 2.4 at 95\% confidence level on the di-Higgs production and constraints for ${\kappa }_{\lambda }$ between -0.6 and 6.6. The obtained confidence interval for ${\kappa }_{2V}$ coupling modifier are [0.1,2.0]. The High Luminosity Large Hadron Collider prospects have been considered as well. The expected signal strength is 0.55 and ${\kappa }_{\lambda }$ between 0.0 and 2.5 for the baseline scenario.

    ↳ hep-exhep-ph5 citations
25. 25*

    Novel tests of gravity using nano-Hertz stochastic gravitational-wave background signals

    Enrico Cannizzaro🇮🇹 · Gabriele Franciolini🇮🇹 · Paolo Pani🇮🇹

    Gravity theories that modify General Relativity in the slow-motion regime can introduce nonperturbative corrections to the stochastic gravitational-wave background~(SGWB) from supermassive black-hole binaries in the nano-Hertz band, while remaining perturbative in the highly-relativistic regime and satisfying current post-Newtonian~(PN) constraints. We present a model-agnostic formalism to map such theories into a modified tilt for the SGWB spectrum, showing that negative PN corrections (in particular -2PN) can alleviate the tension in the recent pulsar-timing-array data if the detected SGWB is interpreted as arising from supermassive binaries. Despite being preliminary, current data have already strong constraining power, for example they set a novel (conservative) upper bound on theories with time-varying Newton's constant at least at the level of $\dot{G}/G\lesssim 10^{-5}{\text{yr}}^{-1}$ for redshift $z=[0.1÷1]$. We also show that NANOGrav data are best fitted by a broken power-law interpolating between a dominant -2PN or -3PN modification at low frequency, and the standard general-relativity scaling at high frequency. Nonetheless, a modified gravity explanation should be confronted with binary eccentricity, environmental effects, nonastrophysical origins of the signal, and scrutinized against statistical uncertainties. These novel tests of gravity will soon become more stringent when combining all pulsar-timing-array facilities and when collecting more data.

    ↳ gr-qcastro-ph.COastro-ph.HEhep-phJCAP(2024)·32 citations
26. 26*

    Gravitational form factors of the pion from lattice QCD

    Daniel C. Hackett🇺🇸 · Patrick R. Oare🇺🇸 · Dimitra A. Pefkou🇺🇸 · Phiala E. Shanahan🇺🇸

    The two gravitational form factors of the pion, $A^{\pi }(t)$ and $D^{\pi }(t)$, are computed as functions of the momentum transfer squared $t$ in the kinematic region $0\le -t<2{\text{GeV}}^2$ on a lattice QCD ensemble with quark masses corresponding to a close-to-physical pion mass $m_{\pi }\approx 170\text{MeV}$ and $N_f=2+1$ quark flavors. The flavor decomposition of these form factors into gluon, up/down light-quark, and strange-quark contributions is presented in the $\overline{\text{MS}}$ scheme at energy scale $\mu =2\text{GeV}$, with renormalization factors computed nonperturbatively via the RI-MOM scheme. Using monopole and $z$-expansion fits to the gravitational form factors, we obtain estimates for the pion momentum fraction and $D$-term that are consistent with the momentum fraction sum rule and the next-to-leading order chiral perturbation theory prediction for $D^{\pi }(0)$.

    ↳ hep-lathep-phhep-thPRD(2023)·96 citations
27. 27*

    Exorcizing Ghosts from the Vacuum Spectra in String-inspired Nonlocal Tachyon Condensation

    Florian Nortier🇫🇷

    Tachyon condensation in quantum field theory (QFT) plays a central role in models of fundamental interactions and cosmology. Inspired by tower truncation in string field theory, ultraviolet completions were proposed with infinite-derivative form factors that preclude the appearance of pathological ghosts in the particle spectrum, contrary to other local higher-derivative QFT's. However, if the infinite-derivative QFT exhibits other vacua, each of them has its own spectrum, which is generally not ghost-free: an infinite tower of ghost-like resonances pops up above the nonlocal scale at tree-level, whose consistency is unclear. In this article, a new weakly nonlocal deformation of a generic local QFT is introduced via a Lorentz and gauge covariant star-product of fields, which is commutative but nonassociative in general. This framework realizes tachyon condensation without ghosts at the perturbative level, with applications for spontaneous symmetry breaking.

    ↳ hep-thhep-phActa Phys.Polon.B(2023)·3 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.