Tue·Apr 18, 2023Tuesday·April 18, 2023

1. 01*

   To (b)e or not to (b)e: No electrons at LHCb

   Marcel Algueró🇪🇸 · Aritra Biswas🇪🇸 · Bernat Capdevila🇮🇹 · Sébastien Descotes-Genon🇫🇷 · Joaquim Matias🇪🇸 · Martín Novoa-Brunet🇮🇹

   We discuss the impact of the recent LHCb update on the two lepton-flavour universality ratios $R_K$ and $R_{K^{\ast }}$, and the CMS update of $B(B_s\to {\mu }^{+}{\mu }^{-})$ regarding the possibility of New Physics in $b\to s{\ell }^{+}{\ell }^{-}$ decays. We perform global fits of the New Physics Wilson coefficients defined in the model-independent approach of the Weak Effective Theory at the $b$-quark mass. We discuss three different frameworks for this analysis: i) an update limited to the experimental data using the same theoretical framework as in earlier works, ii) a full update concerning both the experimental inputs and the theoretical framework, iii) an analysis without the LHCb results on electron modes. The comparison between these sets of results allows us to identify the differences stemming from the various components of the analysis: new experimental results, new inputs for the hadronic form factors, the role played by LHCb data on electron modes. As expected, the significance of all New Physics hypotheses gets reduced after the LHCb announcements on $R_{K^{(\ast )}}$ while the hypothesis of a lepton-flavour-universal contribution to the Wilson coefficient of the semileptonic $O_{9\ell }$ operators (possibly with a very small lepton-flavour-universality violating component) is reinforced. We also discuss the possibility of a long-distance charm-loop contribution through a mode-by-mode analysis and we find that the preferred values for the ${\mathcal{C}}_{9\mu }$ Wilson coefficient are consistent throughout the different $b\to s{\mu }^{+}{\mu }^{-}$ modes and that there is no significant evidence of non-constant $q^2$ dependencies, which would indicate the presence of a long-distance charm-loop contribution beyond those already included.

   hep-phhep-exEPJC(2023)·161 citations
2. 02*

   Freeze-in baryogenesis and early matter domination

   Ioannis Dalianis🇬🇷 · Andreas Goudelis🇫🇷 · Dimitrios Karamitros🇬🇧 · Pantelis Papachristou🇬🇷 · Vassilis C. Spanos🇬🇷

   The freeze-in mechanism has been shown to allow the simultaneous generation of cosmic dark matter and a viable matter-antimatter asymmetry in the universe. When the underlying interactions are described by higher-dimensional, non-renormalizable operators, the relevant freeze-in processes take place close to the highest considered cosmic temperatures. In this paper we study how the presence of a fluid that temporarily dominates the energy content of the early universe affects the predictions of this ``Ultraviolet Freeze-In Baryogenesis'' scenario. We find that this additional cosmic component has a significant impact on the predictions of concrete microscopic models, allowing for reheating temperatures which are much lower than those required in the simplest cosmological scenario. Moreover, we show that inflationary observables can constrain the parameter space of such models, once the latter are examined in conjunction with concrete models of inflation.

   hep-phastro-ph.COPRD(2023)·3 citations
3. 03*

   Heavy baryon spectroscopy in a quark-diquark approach

   A. Torcato🇵🇹 · A. Arriaga🇵🇹 · G. Eichmann🇦🇹 · M. T. Peña🇵🇹

   We report progress on calculations of the heavy-light baryons ${\Sigma }_c$ and ${\Lambda }_c$ and their excitations with $J^P=1/2^{+}$ using functional methods. We employ a covariant quark-diquark approach, where the interaction amounts to a quark exchange between quarks and diquarks and the ingredients are determined from the quark level. A partial-wave analysis reveals the presence of orbital angular momentum components in terms of p waves, which are non-relativistically suppressed.

   hep-phhep-latnucl-thFew Body Syst.(2023)·9 citations
4. 04*

   A minimal axion model for mass matrices with five texture-zeros

   Yithsbey Giraldo🇨🇴 · R. Martínez🇨🇴 · Eduardo Rojas🇨🇴 · Juan C. Salazar🇨🇴

   A model with fermion and scalar fields charged under a Peccei-Queen~(PQ) symmetry is proposed. The PQ charges are chosen in such a way that they can reproduce mass matrices with five texture zeros, {which can generate} the fermion masses, the CKM matrix, and the PMNS matrix of the Standard Model~(SM). To obtain this result, at least 4~Higgs doublets are needed. As we will see in the manuscript this is a highly non-trivial result since the texture zeros of the mass matrices impose a large number of restrictions. This model shows a route to understand the different scales of the SM by extending it with a multi-Higgs sector and an additional PQ symmetry. Since the PQ charges are not universal, the model presents flavor-changing neutral currents~(FCNC) at the tree level, a feature that constitutes the main source of restrictions on the parameter space. We report the allowed regions by lepton decays and compare them with those coming from the semileptonic decays $K^{\pm }⟶\pi \bar{\nu }\nu$. We also show the excluded regions and the projected bounds of future experiments for the axion-photon coupling as a function of the axion mass and compare it with the parameter space of our model.

   hep-phEPJC(2023)·1 citation
5. 05*

   Light cold dark matter from non-thermal decay

   Ki-Young Choi🇰🇷 · Jinn-Ouk Gong🇰🇷 · Junghoon Joh🇰🇷 · Wan-Il Park🇰🇷 · Osamu Seto🇯🇵

   We investigate the mass range and the corresponding free-streaming length scale of dark matter produced non-thermally from decay of heavy objects which can be either dominant or sub-dominant at the moment of decay. We show that the resulting dark matter could be very light well below keV scale with a free-streaming length satisfying the Lyman-{\alpha} constraints. We demonstrate two explicit examples for such light cold dark matter.

   hep-phastro-ph.COPLB(2023)·9 citations
6. 06*

   Associated production of $J/\psi$ plus $Z(W)$ in the improved color evaporation model using the parton Reggeization approach

   Alexey Chernyshev🇷🇺 · Vladimir Saleev🇷🇺

   In the article, we study the associated production of prompt $J/\psi$ mesons and $Z(W)$ bosons in the improved color evaporation model using the high-energy factorization as it is formulated in the parton Reggeization approach. The last one is based on the modified Kimber-Martin-Ryskin-Watt model for unintegrated parton distribution functions and the effective field theory of Reggezied gluons and quarks, suggested by L.N.~Lipatov. We predict cross section for associated $J/\psi$ and $Z(W)$ hadroproduction via the single and double parton scattering mechanisms using the set of model parameters that have been obtained early for the description of single and double prompt $J/\psi$ production at the LHC energies. The numerical calculations are realized using the Monte-Carlo event generator KaTie. The calculation results are compared with the data at the energies $\sqrt{s}=7\text{mbox}and8$ TeV and we make predictions for the energy $\sqrt{s}=13$ TeV for $J/\psi$ plus $Z(W)$ and ${\rm Y}$ plus $Z/W$ at the $\sqrt{s}=8\text{mbox}and13$ TeV associated productions.

   hep-phInt.J.Mod.Phys.A(2023)·4 citations
7. 07*

   Instanton induced spin-spin correlations

   M. G. Ryskin🇷🇺

   The QCD instanton can be observed at relatively low energies at Nica collider by studying the spin-spin correlations between the incoming proton and the produced hyperons .

   hep-phEPJC(2023)·1 citation
8. 08*

   The Higgs Boson and its Physics -- an Overview

   Sreerup Raychaudhuri🇮🇳

   The Higgs boson plays a central role in the Standard Model, as well as in theories which go beyond it. This article is therefore divided into two parts. The first takes s historical approach and shows how the mass problem entered weak interaction theory from the beginning and how it was solved by invoking the Higgs boson. This is followed by a construction of the Glashow-Salam-Weinberg model, again stressing the role played by the Higgs doublet. This part culminates in the Higgs boson discovery of 2012. The second part first discusses the shortcomings of the Standard Model and then touches upon the major theories which try to improve upon it, mostly with profound consequences on the Higgs sector. This is followed up by short descriptions of a number of popular extensions of the Higgs sector, and culminates in a brief introduction to effective field theory approaches to studying the Higgs sector.

   hep-phIndian J.Phys.(2023)·5 citations
9. 09*

   Propagators and widths of physical and purely virtual particles in a finite interval of time

   Damiano Anselmi🇮🇹

   We study the free and dressed propagators of physical and purely virtual particles in a finite interval of time $\tau$ and on a compact space manifold $\Omega$, using coherent states. In the free-field limit, the propagators are described by the entire function $(e^z-1-z)/z^2$, whose shape on the real axis is similar to the one of a Breit-Wigner function, with an effective width around $1/\tau$. The real part is positive, in agreement with unitarity, and remains so after including the radiative corrections, which shift the function into the physical half plane. We investigate the effects of the restriction to finite $\tau$ on the problem of unstable particles vs resonances, and show that the muon observation emerges from the right physical process, differently from what happens at $\tau =\infty$. We also study the case of purely virtual particles, and show that, if $\tau$ is small enough, there exists a situation where the geometric series of the self-energies is always convergent. The plots of the dressed propagators show testable differences: while physical particles are characterized by the usual, single peak, purely virtual particles are characterized by twin peaks.

   hep-phhep-thJHEP(2023)·11 citations
10. 10*

    Analysis of strong coupling constant with machine learning and its application

    Xiao-Yun Wang🇨🇳 · Chen Dong🇨🇳 · Xiang Liu🇨🇳

    In this work, we investigate the nature of the strong coupling constant and related physics. Through the analysis of accumulated experimental data from around the world, we employ the ability of machine learning to unravel its physical laws. The result of our efforts is a formula that captures the expansive panorama of the distribution of the strong coupling constant across the entire energy range. Importantly, this newly derived expression is very similar to the formula derived from the Dyson-Schwinger equations based on the framework of Yang-Mills theory. By introducing the Euler number, $e$, into the functional formula of the strong coupling constant at high energies, we have successfully solved the puzzle of the infrared divergence, which allows for a seamless transition of the strong coupling constant from the perturbative to the non-perturbative energy regime. Moreover, the obtained ghost and gluon dressing function distribution results confirm that the obtained strong coupling constant formula can well describe the physical properties of the non-perturbed regime. In addition, we investigate the QCD strong coupling constant result of the Bjorken sum rule ${\Gamma }_1^{p-n}$ and the quark-quark static energy $E_0(r)$, and find that the global energy scale can effectively interpret the experimental data. The results presented in this work shed light on the puzzling properties of quantum chromodynamics and the intricate interplay of strong coupling constants at both low and high energy scales.

    hep-phChin.Phys.Lett.(2023)·10 citations
11. 11*

    Baryons in the light-front approach: The three-quark picture

    Zhen-Xing Zhao🇨🇳 · Fu-Wei Zhang🇨🇳 · Xiao-Hui Hu🇨🇳 · Yu-Ji Shi🇨🇳

    In this work, a three-quark picture is constructed using a bottom-up approach for baryons in light-front quark model. The shape parameters, which characterize the momentum distribution inside a baryon, are determined with the help of the pole residue of the baryon. The relation between the three-quark picture and the diquark picture is clarified. When building the model, we find that Lorentz boost plays a crucial role, and the bottom-up modeling approach can be generalized to multiquark states. Based on this, a unified theoretical framework for describing multiquark states may be established. As a by-product of model construction, we can easily obtain a newly improved definition of baryon interpolating current. The hadron interpolating currents are the starting point of Lattice QCD and QCD sum rules, and therefore are of great importance.

    hep-phPRD(2023)·15 citations
12. 12*

    Electroweak Multi-Higgs Production: A Smoking Gun for the Type-I Two-Higgs-Doublet Model

    Tanmoy Mondal🇯🇵 · Stefano Moretti🇬🇧 · Shoaib Munir🇷🇼 · Prasenjit Sanyal🇰🇷

    Extending the Higgs sector of the Standard Model (SM) by just one additional Higgs doublet field leads to the two-Higgs-doublet model (2HDM). In the Type-I $Z_2$-symmetric limit of the 2HDM, all the five new physical Higgs states can be fairly light, $\mathcal{O}(100)$\,GeV or less, without being in conflict with current data from the direct Higgs boson searches and the $B$-physics measurements. In this article, we establish that the new neutral as well as the charged Higgs bosons in this model can all be simultaneously observable in the multi-$b$ final state. The statistical significance of the signature for each of these Higgs states, resulting from the electro-weak (EW) production of their pairs, can exceed 5$\sigma$ at the 13\,TeV High-Luminosity Large Hadron Collider (HL-LHC). Since the parameter space configurations where this is achievable are precluded in the other, more extensively pursued, 2HDM Types, an experimental validation of our findings would be a clear indication that the true underlying Higgs sector in nature is the Type-I 2HDM.

    hep-phPRL(2023)·13 citations
13. 13*

    Constraint for a light charged Higgs boson and its neutral partners from top quark pairs at the LHC

    ChunHao Fu🇨🇳 · Jun Gao🇨🇳

    The charged Higgs boson plays an essential role in distinguishing between a wide variety of standard model extensions with multiple Higgs doublets, and has been searched for in various collider experiments. This paper expands our previous work to a broader Higgs mass space with discussions on subsequent issues. We study the prospect of a light charged Higgs boson, produced by top quark pairs at the Large Hadron Collider (LHC), and decaying into a $W$ boson (can be off shell) and a pair of bottom quarks via on-shell production of an intermediate neutral Higgs boson. We reinterpret the cross sections of $WWbb\bar{b}\bar{b}$ final states measured by the ATLAS collaboration at LHC 13 TeV in the presence of the decay chain: $t\to H^{+}b,H^{+}\to W^{+}{H}_i,H_i\to b\bar{b}$, and H.c., where $H_i$ is a neutral Higgs boson variably lighter than the charged Higgs boson. We find improved agreements with the data and obtain limits on the total branching ratio of the aforementioned decay chain. The limits impose the strongest constraints on the parameter space of type-I two-Higgs-doublet model for most Higgs masses sampled when $H_i$ is the $CP$-odd Higgs boson $A$. We also calculate potential constraints with pseudodata in high-luminosity runs of the LHC.

    hep-phhep-exPRD(2023)·4 citations
14. 14*

    Grand unification, small vs large representations, hadron colliders and all that

    Goran Senjanović🇩🇪 · Michael Zantedeschi🇨🇳

    We review minimal realistic grand unified models based on $SU(5)$ and $SO(10)$ gauge groups. The models with small Higgs representations and higher dimensional operators - under the assumption of no cancellations in proton decay amplitudes - predict nearby oases with new light particles. Two of them stand out: real fermion and scalar weak triplets. The former generates dynamically neutrino Majorana mass through the so-called type III seesaw mechanism, while the latter naturally gets a small vacuum expectation value and thus generically modifies $W$-boson mass. On the contrary, the renormalisable versions of these theories fail to determine the particle spectra. In particular, in the renormalisable version of the $SO(10)$ theory the mass of the right-handed gauge boson - normally assumed (and allowed) to lie far in the desert - could be even accessible at the LHC. Last but not least, we show that in the minimal supersymmetric $SU(5)$ theory all the superpartners can lie orders of magnitude above the weak scale, unless one requires strict naturalness. Thus, the so-called split supersymmetry does not imply any light states.

    hep-phhep-exhep-thPoS(2023)·5 citations
15. 15*

    First characterization of the scattering length distribution of vector meson interaction with deuteron

    Xiao-Yun Wang🇨🇳 · Chen Dong🇨🇳 · Quanjin Wang🇨🇳

    Under the framework of the vector meson dominance model (VMD), the absolute scattering lengths of light vector mesons ($\varphi$, $\omega$, and $\rho$) with the deuteron are calculated from the cross sections of vector meson photoproduction off a deuteron. Additionally, a fitting function is used to predict the scattering lengths of the heavy vector mesons $J/\psi$-$d$ and -$d$. Based on these results, the distribution of the scattering lengths $|{\alpha }_{Vd}|$ between vector mesons and the deuteron is presented for the first time and compared with the scattering lengths $|{\alpha }_{Vp}|$ between vector mesons and the proton. It is found that as the mass of the vector meson increases, the scattering lengths $|{\alpha }_{Vd}|$ become closer to $|{\alpha }_{Vp}|$. In addition, the correlation analysis indicates a strong positive relationship between the scattering length and the vector meson radius, with a high correlation coefficient. The implications of results are essential for improving our understanding of the interaction between hadron and nucleus.

    hep-phnucl-thPRC(2023)·4 citations
16. 16*

    Constraints on NJL four-fermion effective interactions from neutrinoless double beta decay

    Luca Pacioselli (1 and 2)🇮🇹 · Orlando Panella (2)🇮🇹 · Matteo Presilla (3)🇮🇹 · She-Sheng Xue (2, 4, 5 and 6) ((1) Dipartimento di Fisica e Geologia, Università degli Studi di Perugia, (2) INFN Sezione di Perugia, (3) Institute for Experimental Particle Physics (ETP), Karlsruhe Institute of Technology, Karlsruhe, Germany, (4) ICRANet, Pescara, (5) Dipartimento di Fisica, Sapienza-Università di Roma, (6) ICTP-AP, University of Chinese Academy of Sciences, Beijing, China)🇮🇹

    We study the contribution of a heavy right-handed Majorana neutrino to neutrinoless double beta decay ($0\nu \beta \beta$) via four-fermion effective interactions of Nambu-Jona-Lasinio (NJL) type. In this physical scenario, the sterile neutrino contributes to the nuclear transition through gauge, contact, and mixed interactions. Using the lower limit on the half-life of $0\nu \beta \beta$ from the KamLAND-Zen experiment, we then constrain the effective right-handed coupling between the sterile neutrino and the $W$ boson: ${\mathcal{G}}_R^W$. Eventually, we show that the obtained bounds are compatible with those found in the literature, which highlights the complementarity of this type of phenomenological study with high-energy experiments.

    hep-phJHEP(2023)·3 citations
17. 17*

    Density dependent displaced vertex signatures as a novel probe of light dark sector scalars at the LHC

    Spyros Argyropoulos🇩🇪 · Clare Burrage🇬🇧 · Christoph Englert🇬🇧

    Dynamical theories of dark energy predict new degrees of freedom with particular environmental sensitivity to avoid constraints on fifth forces. We show that the similar, yet complementary multi-purpose detector setup of the ATLAS and CMS experiments provides a unique opportunity to place sensitivity on such scenarios in a narrow, yet relevant parameter range. Furthermore, our investigation gives rise to a novel phenomenological signature that the LHC experiments can pursue to exploit their complementary detector design from a BSM perspective.

    hep-phhep-exJCAP(2024)·4 citations
18. 18*

    Pileup density estimate independent on jet multiplicity

    Peter Berta🇨🇿 · Juraj Smieško🇨🇭 · Martin Spousta🇨🇿

    The hard-scatter processes in hadronic collisions are often largely contaminated with soft background coming from pileup in proton-proton collisions, or underlying event in heavy-ion collisions. There are multiple methods to remove the effect of pileup for jets. Two such methods, Area Subtraction and Constituent Subtraction, use the pileup density as the main ingredient to estimate the magnitude of pileup contribution on an event-by-event basis. The state-of-the-art approaches to estimating pileup density are sensitive to the number of hard-scatter jets in the event. This paper presents a new pileup-density estimation method that minimizes the sensitivity on the presence of hard-scatter jets in the event. Using a detector-level simulation, we provide a comparison of the new method with the state-of-the-art estimation methods. We observe a significantly lower bias for the estimated pileup density when using the new method. We conclude that the new method has the potential to significantly improve pileup mitigation in proton-proton collisions or the underlying event subtraction in heavy-ion collisions.

    hep-phhep-exJHEP(2024)·0 citations
19. 19*

    Charmed hadron lifetimes

    James Gratrex🇭🇷 · Blaženka Melić🇭🇷 · Ivan Nišandžić🇭🇷

    We provide updated predictions of the lifetimes of singly charmed baryons and mesons within the heavy quark expansion, with all known corrections included. A special attention is devoted to the choice of the charm mass and wavefunctions of heavy baryons. Our results accommodate the experimentally-favoured hierarchy of singly charmed baryon lifetimes \begin{eqnarray*} \tau(\Xi_c^0) < \tau(\Lambda_c^+)< \tau(\Omega_c^0) < \tau(\Xi_c^+)\, \end{eqnarray*} in contrast to earlier theoretical findings. Predictions for charmed meson lifetimes and semileptonic branching ratios are also in agreement, within uncertainties, with a recent comprehensive study and with experimental results.

    hep-phPoS(2023)·1 citation
20. 20*

    Low Seesaw Scale Solution for $M_W$ and $(g-2{)}_{\mu }$

    A. de Giorgi🇪🇸 · L. Merlo🇪🇸 · S. Pokorski🇵🇱

    In this short talk, we present a renormalizable model that can i) generate neutrino masses via a low-scale seesaw mechanism and ii) solve the long-standing $(g-2{)}_{\mu }$ and the more recent CDF II $M_W$-anomalies. This is minimally achieved by introducing two sterile neutrinos and a single electroweak-doublet vector-like lepton, with masses $<2$ TeV. We focus on the one-generation scenario and the requirements to extend it to three generations.

    hep-ph0 citations
21. 21*

    Big Bang initial conditions and self-interacting hidden dark matter

    Jinzheng Li🇺🇸 · Pran Nath🇺🇸

    A variety of supergravity and string models involve hidden sectors where the hidden sectors may couple feebly with the visible sectors via a variety of portals. While the coupling of the hidden sector to the visible sector is feeble its coupling to the inflaton is largely unknown. It could couple feebly or with the same strength as the visible sector which would result in either a cold or a hot hidden sector at the end of reheating. These two possibilities could lead to significantly different outcomes for observables. We investigate the thermal evolution of the two sectors in a cosmologically consistent hidden sector dark matter model where the hidden sector and the visible sector are thermally coupled. Within this framework we analyze several phenomena to illustrate their dependence on the initial conditions. These include the allowed parameter space of models, dark matter relic density, proton-dark matter cross section, effective massless neutrino species at BBN time, self-interacting dark matter cross-section, where self-interaction occurs via exchange of dark photon, and Sommerfeld enhancement. Finally fits to the velocity dependence of dark matter cross sections from galaxy scales to the scale of galaxy clusters is given. The analysis indicates significant effects of the initial conditions on the observables listed above. The analysis is carried out within the framework where dark matter is constituted of dark fermions and the mediation between the visible and the hidden sector occurs via the exchange of dark photons. The techniques discussed here may have applications for a wider class of hidden sector models using different mediations between the visible and the hidden sectors to explore the impact of Big Bang initial conditions on observable physics.

    hep-phastro-ph.COastro-ph.HEPRD(2023)·11 citations
22. 22*

    Vectorlike leptons and long-lived bosons at the LHC

    Elias Bernreuther🇺🇸 · Bogdan A. Dobrescu🇺🇸

    We study a renormalizable theory that includes a heavy weak-singlet vectorlike lepton, ${\tau }^{\prime }$, that decays into a pseudoscalar boson and a tau lepton. We show that this can be the dominant decay mode of ${\tau }^{\prime }$ provided the pseudoscalar couplings deviate from the case of a Nambu-Goldstone boson. For a range of parameters, the pseudoscalar is long-lived, and mainly decays into a photon pair at one loop, or into a tau pair at tree level. Electroweak production of ${\tau }^{\prime +}{\tau }^{\prime -}$ leads to a rich phenomenology at colliders, including signals with many taus or photons. We analyze in detail the LHC signal involving two prompt taus and two displaced photon pairs. Particularly interesting is the case where the pseudoscalar has a decay length of a few meters and thus would typically deposit energy in the muon chambers of the CMS or ATLAS detectors.

    hep-phhep-exJHEP(2023)·18 citations
23. 23*

    TASI Lectures: (No) Global Symmetries to Axion Physics

    Matthew Reece🇺🇸

    These notes are an expanded version of lectures given at the 2022 TASI summer school in Boulder, Colorado. One goal of these lecture notes is to (partially) bridge the gap between what one learns in typical introductory quantum field theory classes and what one needs to understand to follow modern developments in particle theory beyond the Standard Model. Topics covered include global and gauge symmetries, charge quantization, instantons, chiral anomalies, the Strong CP problem, axion models from 4d and from higher dimensions, the expected absence of global symmetries in quantum gravity, and some phenomenological implications thereof. If these topics seem to be at best loosely related, I hope that reading the notes will convince you otherwise. Recent developments in quantum field theory have shown that ordinary gauge theories exhibit a much wider range of (generalized) global symmetries than were previously understood, while recent work in quantum gravity has provided sharper arguments that global symmetries should not exist. This sets up an interesting tension, the resolution of which can have implications for particle physics in the real world. Axion physics is one setting in which these ideas can guide phenomenology. The TASI audience comprised particle phenomenology students whom I hoped to convince of the importance of learning more about quantum field theory and quantum gravity. These notes may also be of interest to formal theory readers seeking closer connections to real-world particle physics.

    hep-phhep-thPoS(2024)·89 citations
24. 24*

    Exorcising the Ghost Condensate Dark Energy with a Sextic Dispersion Relation

    A. Ashoorioon🇮🇷 · A. Yousefi-Sostani🇮🇷

    The universe's current acceleration is a pretty recent phenomenon in cosmological time scales. This means that the modes that have left our horizon since the beginning of the contemporary acceleration phase, have not really reached the exact IR limit. Noting this observation, we reconsider the possibility of having a ghost condensate as dark energy with a sixth-order dispersion relation. Looking at the three-point function of such a theory, we obtain the constraints on the coefficient of the sixth-order dispersion relation to avoid strong coupling. Such a ghost condensate if coupled to the standard model fields, induces a constant Lorentz-violating spin-dependent force, which can gravitate or anti-gravitate.

    ↳ hep-thastro-ph.COhep-phPLB(2023)·2 citations
25. 25*

    The worldline formalism in strong-field QED

    Christian Schubert🇲🇽

    The worldline formalism provides an alternative to Feynman diagrams that has been found particularly useful for external-field calculations in quantum electrodynamics. Here I summarize its present range of applications, which includes Schwinger pair creation, photon splitting in constant fields and plane-wave backgrounds, as well as nonlinear Compton scattering in constant fields.

    ↳ hep-thhep-phphysics.plasm-phJ.Phys.Conf.Ser.(2023)·10 citations
26. 26*

    Quantum field theory of physical and purely virtual particles in a finite interval of time on a compact space manifold: diagrams, amplitudes and unitarity

    Damiano Anselmi🇮🇹

    We provide a diagrammatic formulation of perturbative quantum field theory in a finite interval of time $\tau$, on a compact space manifold $\Omega$. We explain how to compute the evolution operator $U(t_{\text{f}},t_{\text{i}})$ between the initial time $t_{\text{i}}$ and the final time $t_{\text{f}}=t_{\text{i}}+\tau$, study unitarity and renormalizability, and show how to include purely virtual particles, by rendering some physical particles (and all the ghosts, if present) purely virtual. The details about the restriction to finite $\tau$ and compact $\Omega$ are moved away from the internal sectors of the diagrams (apart from the discretization of the three-momenta), and coded into external sources. So doing, the diagrams are as similar as possible to the usual $S$ matrix diagrams, and most known theorems extend straightforwardly. Unitarity is studied by means of the spectral optical identities, and the diagrammatic version of the identity $U^{†}(t_{\text{f}},t_{\text{i}})U(t_{\text{f}},t_{\text{i}})=1$. The dimensional regularization is extended to finite $\tau$ and compact $\Omega$, and used to prove, under general assumptions, that renormalizability holds whenever it holds at $\tau =\infty$, $\Omega ={\mathbb{R}}^3$. Purely virtual particles are introduced by removing the on-shell contributions of some physical particles, and the ghosts, from the core diagrams, and trivializing their initial and final conditions. The resulting evolution operator $U_{\text{ph}}(t_{\text{f}},t_{\text{i}})$ is unitary, but does not satisfy the more general identity $U_{\text{ph}}(t_3,t_2)U_{\text{ph}}(t_2,t_1)=U_{\text{ph}}(t_3,t_1)$. As a consequence, $U_{\text{ph}}(t_{\text{f}},t_{\text{i}})$ cannot be derived from a Hamiltonian in a standard way, in the presence of purely virtual particles.

    ↳ hep-thhep-phJHEP(2023)·13 citations
27. 27*

    Double-strangeness exchange reactions in a hybrid Regge-plus-resonance approach

    Sang-Ho Kim🇰🇷 · Jung Keun Ahn🇰🇷 · Shin Hyung Kim🇯🇵 · Seung-il Nam🇰🇷 · Myung-Ki Cheoun🇰🇷

    We investigate double-strangeness exchange reactions, $K^{-}p\to K^{+}{\Xi }^{-}$ and $K^{-}p\to K^0{\Xi }^0$, using an effective Lagrangian approach based on a hybrid Regge-plus-resonance model involving rescattering diagrams. We consider the background processes that include $\Lambda$, $\Sigma$, and $\Sigma (1385)$ Regge trajectories in the $u$ channel and the $s$-channel Born-term diagrams. The $s$-channel hyperon resonances account for the bump structures in the total cross sections. The $s$-channel $\Lambda (2100,7/2^{-})$ and $\Sigma (2030,7/2^{+})$ resonances contribute significantly, and the $\Sigma (2250)$ resonance favors $J^P=7/2^{-}$. The interference pattern between the $\Lambda (2100,7/2^{-})$ and $\Sigma (2030,7/2^{+})$ amplitudes is essential for describing forward differential cross sections in the resonance region $2.07<\sqrt{s}<2.15$ GeV. The absence of the $S=-2$ meson leads to the inclusion of the meson-baryon rescattering diagrams to describe the $K^{-}p\to K\Xi$ reaction data, proving the significant contribution of the $(\varphi ,\rho ,\omega )$--$(\Lambda ,\Sigma )$ rescattering diagrams.

    ↳ nucl-thhep-phPRC(2023)·10 citations
28. 28*

    Evidence of the Schwinger mechanism from lattice QCD

    Mauricio Narciso Ferreira🇪🇸

    In quantum chromodynamics (QCD), gluons acquire a mass scale through the action of the Schwinger mechanism. This mass emerges as a result of the dynamical formation of massless bound-states of gluons which manifest as longitudinally coupled poles in the vertices. In this contribution, we show how the presence of these poles can be determined from lattice QCD results for the propagators and vertices. The crucial observation that allows this determination is that the Schwinger mechanism poles induce modifications, called ``displacements'', to the Ward identities (WIs) relating two- and three-point functions. Importantly, the displacement functions correspond precisely to the Bethe-Salpeter amplitudes of the massless bound-states. We apply this idea to the case of the three-gluon vertex in pure Yang-Mills SU(3). Using lattice results in the corresponding WI, we find an unequivocal displacement and show that it is consistent with the prediction based on the Bethe-Salpeter equation.

    ↳ hep-lathep-phhep-thnucl-thFew Body Syst.(2023)·1 citation
29. 29*

    Tabulated Equations of State From Models Informed by Chiral Effective Field Theory

    Mark G. Alford🇺🇸 · Liam Brodie🇺🇸 · Alexander Haber🇺🇸 · Ingo Tews🇺🇸

    We construct four equation of state (EoS) tables, tabulated over a range of temperatures, densities, and charge fractions, relevant for neutron star applications such as simulations of neutron star mergers. The EoS are computed from a relativistic mean-field theory constrained by the pure neutron matter EoS from chiral effective field theory, inferred properties of isospin-symmetric nuclear matter, and astrophysical observations of neutron star structure. To model nuclear matter at low densities, we attach an EoS that models inhomogeneous nuclear matter at arbitrary temperatures and charge fractions. The four EoS tables we develop are available from the CompOSE EoS repository compose.obspm.fr/eos/297 and gitlab.com/ahaber/qmc-rmf-tables.

    ↳ nucl-thastro-ph.HEhep-phPhys.Scripta(2023)·17 citations
30. 30*

    A Proposed Renormalization Scheme for Non-local QFTs and Application to the Hierarchy Problem

    Fayez Abu-Ajamieh🇮🇳 · Sudhir K. Vempati🇮🇳

    We propose a renormalization scheme for non-local Quantum Field Theories (QFTs) with infinite derivatives inspired by string theory. Our Non-locality Renormalization Scheme (NRS) is inspired by Dimensional Regularization (DR) in local QFTs and is shown to significantly improve the UV behavior of non-local QFTs. We illustrate the scheme using simple examples from the phi3 and phi4 theories, then we evaluate the viability of NRS-enhanced non-local QFTs to solve the hierarchy problem using a simplified toy model. We find that non-locality protects the mass of a light scalar from receiving large corrections from any UV sector to which it couples, as long as the non-locality scale M is sufficiently smaller than the scale of the UV sector. We also find that NRS eliminates any large threshold corrections from the IR sector

    ↳ hep-thhep-phEPJC(2023)·10 citations
31. 31*

    Naturalness and UV sensitivity in Kaluza-Klein theories

    Carlo Branchina🇫🇷 · Vincenzo Branchina🇮🇹 · Filippo Contino🇮🇹

    More than twenty years ago a paradigm emerged according to which a UV-insensitive Higgs mass $m_H$ and (more generally) a UV-insensitive Higgs effective potential $V_{1l}(\varphi )$ are obtained from higher-dimensional theories with compact extra dimensions and Scherk-Schwarz supersymmetry breaking. Since then, these ideas have been applied to different models of phenomenological interest, including recent applications to the dark energy problem. A thorough analysis of the framework on which such a paradigm is based allows us to show that a source of strong UV sensitivity for $m_H$ and $V_{1l}(\varphi )$, intimately connected to the non-trivial topology of these models' spacetime, was missed. The usual picture of the Scherk-Schwarz mechanism and its physical consequences need to be seriously reconsidered.

    ↳ hep-thhep-phPRD(2023)·15 citations
32. 32*

    Supermassive primordial black holes: a view from clustering of quasars at $z\sim 6$

    Takumi Shinohara🇯🇵 · Wanqiu He🇨🇳 · Yoshiki Matsuoka🇯🇵 · Tohru Nagao🇯🇵 · Teruaki Suyama🇯🇵 · Tomo Takahashi🇯🇵

    We investigate a scenario where primordial black holes (PBHs) can be the progenitors of supermassive black holes (SMBHs) observed at $z\sim 6$. To this end, we carried out clustering analysis using a sample of 81 quasars at $5.88<z<6.49$, which is constructed in Subaru High-$z$ Exploration of Low-Luminosity Quasars (SHELLQs) project, and 11 quasars in the same redshift range selected from the literature. The resulting angular auto-correlation function (ACF) can be fitted to a power-law form of ${\omega }_{\theta }=0.045_{-0.106}^{+0.114}{\theta }^{-0.8}$ over a scale of $0.2-10$ degrees. We compare the ACF of the quasars to that predicted for the PBH model at $z\sim 6$ and found that such a scenario is excluded for a broad range of parameter space, from which we can conclude that a scenario with PBHs as SMBHs is not viable. We also discuss a model in which SMBHs at $z\sim 6$ originate from the direct collapse of PBH clumps and argue that the observed ACF excludes such a scenario in the context of our PBH model.

    ↳ astro-ph.COgr-qchep-phPRD(2023)·15 citations
33. 33*

    Prospects for annihilating dark matter from M31 and M33 observations with the Cherenkov Telescope Array

    Miltiadis Michailidis🇩🇪 · Lorenzo Marafatto🇸🇮 · Denys Malyshev🇩🇪 · Fabio Iocco🇮🇹 · Gabrijela Zaharijas🇸🇮 · Olga Sergijenko🇺🇦 · Maria Isabel Bernardos🇮🇹 · Christopher Eckner🇫🇷 · Alexey Boyarsky🇳🇱 · Anastasia Sokolenko🇺🇸 · Andrea Santangelo🇩🇪

    M31 and M33 are the closest spiral galaxies and the largest members (together with the Milky Way) of the Local group, which makes them interesting targets for indirect dark matter searches. In this paper, we present studies of the expected sensitivity of the Cherenkov Telescope Array (CTA) to an annihilation signal from weakly interacting massive particles from M31 and M33. We show that a 100 h long observation campaign will allow CTA to probe annihilation cross-sections up to $⟨\sigma \upsilon ⟩\approx 5\cdot 10^{-25}$ cm${}^3$s${}^{-1}$ for the ${\tau }^{+}{\tau }^{-}$ annihilation channel (for M31, at a DM mass of 0.3 TeV), improving the current limits derived by HAWC by up to an order of magnitude. We present an estimate of the expected CTA sensitivity, by also taking into account the contributions of the astrophysical background and other possible sources of systematic uncertainty. We also show that CTA might be able to detect the extended emission from the bulge of M31, detected at lower energies by the Fermi/LAT.

    ↳ astro-ph.HEastro-ph.COhep-phJCAP(2023)·3 citations
34. 34*

    Probing Dark Energy and Modifications of Gravity with Ground-Based Millimeter-Wavelength Line Intensity Mapping

    Azadeh Moradinezhad Dizgah🇨🇭 · Emilio Bellini🇮🇹 · Garrett K. Keating🇺🇸

    Line intensity mapping (LIM) can provide a powerful means to constrain the theory of gravity and the nature of dark energy at low and high redshifts by mapping the large-scale structure (LSS) over many redshift epochs. In this paper, we investigate the potential of the next generation ground-based millimeter-wavelength LIM surveys in constraining several models beyond $\Lambda$CDM, involving either a dynamic dark energy component or modifications of the theory of gravity. Limiting ourselves to two-point clustering statistics, we consider the measurements of auto-spectra of several CO rotational lines (from J=2-1 to J=6-5) and the [CII] fine structure line in the redshift range of $0.25<z<12$. We consider different models beyond $\Lambda$CDM, each one with different signatures and peculiarities. Among them, we focus on Jordan-Brans-Dicke and axion-driven early dark energy models as examples of well-studied scalar-tensor theories acting at late and early times respectively. Additionally, we consider three phenomenological models based on an effective description of gravity at cosmological scales. We show that LIM surveys deployable within a decade (with $\sim 10^8$ spectrometer hours) have the potential to improve upon the current bounds on all considered models significantly. The level of improvements range from a factor of a few to an order of magnitude.

    ↳ astro-ph.COgr-qchep-phApJ(2024)·7 citations
35. 35*

    Current and Future constraints on Very-Light Axion-Like Particles from X-ray observations of cluster-hosted Active Galaxies

    Julia M. Sisk-Reynes🇬🇧 · Christopher S. Reynolds🇬🇧 · James H. Matthews🇬🇧

    We discuss our recent constraints on the coupling of Very-Light Axion-Like Particles (of masses $<$$10^{-12}\mathrm{eV}$) to electromagnetism from $Chandra$ observations of the cluster-hosted Active Galactic Nuclei (AGN) H1821+643 and NGC1275. In both cases, the inferred high-quality AGN spectra excluded all photon-ALP couplings $g_{\mathrm{a}\gamma }>(6.3-8.0)\times 10^{-13}{\mathrm{GeV}}^{-1}$ at the $99.7\%$ level, respectively, based on the non-detection of spectral distortions attributed to photon-ALP inter-conversion along the cluster line-of-sight. Finally, we present the prospects of tightening current bounds on such ALPs by up to a factor of 10 with next-generation X-ray observatories such as $Athena$, $AXIS$ and $LEM$ given their improved spectral and spatial resolution and collecting area compared to current missions.

    ↳ astro-ph.HEastro-ph.COastro-ph.GAhep-phMem.Soc.Ast.It.(2023)·1 citation
36. 36*

    Message in a bottle: energy extraction from bouncing geometries

    Vitor Cardoso🇩🇰 · João L. Costa🇵🇹 · José Natário🇵🇹 · Zhen Zhong🇵🇹

    Quantum gravity phenomenology suggests the interesting possibility that black holes are not eternal. Collapse could be halted by some unknown mechanism, or Hawking radiation might leave behind a regular spacetime. Here we investigate a simple bouncing geometry, with (outer and inner) apparent horizons but no event horizon. We show that the inner horizon blueshifts radiation, which can lead to a gigantic amplification of energy observable from far away regions. Thus, if such phenomena exists in our universe, they can power high-energy bursts at late stages in their lives, when the horizons disappear and spacetime bounces back to a flat geometry.

    ↳ gr-qchep-phhep-thPRD(2023)·5 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.