Thu·Feb 10, 2022Thursday·February 10, 2022

1. 01*

   Phenomenology of the hadronic structure at small-$x$

   Francesco Giovanni Celiberto🇮🇹

   We present exploratory studies of the proton structure via two distinct kinds of gluon densities: the transverse-momentum dependent functions, whose evolution is determined by the CSS equation, and the unintegrated gluon distribution, whose definition is given in the BFKL formalism. Our analyses are relevant for the exploration of the intrinsic motion of gluons inside protons in the small-$x$ regime, and for a comprehensive tomographic imaging of the proton at new-generation colliding facilities.

   hep-phhep-ex35 citations
2. 02*

   Gravitational waves in models with multicritical-point principle

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

   The multicritical-point principle (MPP) provides a natural explanation of the large hierarchy between the Planck and electroweak scales. We consider a scenario in which MPP is applied to the Standard Model extended by two real singlet scalar fields $\varphi$ and $S$, and a dimensional transmutation occurs by the vacuum expectation value of $\varphi$. In this paper, we focus on the critical points that possess a ${\mathbb{Z}}_2$ symmetry $S\to -S$ and all the other fields are left invariant. Then $S$ becomes a natural dark matter (DM) candidate. Further, we concentrate on the critical points where $\varphi$ does not possess further ${\mathbb{Z}}_2$ symmetry so that there is no cosmological domain-wall problem. Among such critical points, we focus on maximally critical one called CP-1234 that fix all the superrenormalizable parameters. We show that there remains a parameter region that satisfies the DM relic abundance, DM direct-detection bound and the current LHC constraints. In this region, we find a first-order phase transition in the early universe around the TeV-scale temperature. The resultant gravitational waves are predicted with a peak amplitude of $\mathcal{O}(10^{-12})$ at a frequency of $10^{-2}$-$10^{-1}$ Hz, which can be tested with future space-based instruments such as DECIGO and BBO.

   hep-phastro-ph.COEPJC(2022)·5 citations
3. 03*

   Type-II two-Higgs-doublet model in noncommutative geometry

   Fredy Jimenez🇨🇴 · Diego Restrepo🇨🇴 · Andrés Rivera🇨🇴

   In noncommutative geometry (NCG) the spectral action principle predicts the standard model (SM) particle masses by constraining the scalar and Yukawa couplings at some heavy scale, but gives an inconsistent value for the Higgs mass. Nevertheless, the scalar sector in the NCG approach to the standard model, is in general composed of two Higgs doublets and its phenomenology remains unexplored. In this work, we present a type-II two-Higgs-doublet model in NCG, with a SM-like Higgs mass compatible with the 125~GeV experimental value and extra scalars within the alignment limit without decoupling with masses from 350 GeV.

   hep-phNPB(2022)·0 citations
4. 04*

   Longitudinal structure function $F_L$ at low $Q^2$ and low $x$ with model for higher twist: an update

   B. Badelek🇵🇱 · A.M. Stasto🇺🇸

   A reanalysis of the model for the longitudinal structure function $F_L(x,Q^2)$ at low $x$ and low $Q^2$ was undertaken, in view of the advent of the EIC. The model is based on the photon-gluon fusion mechanism suitably extrapolated to the region of low $Q^2$. It includes the kinematic constraint $F_L\sim Q^4$ as $Q^2\to$ 0 and higher twist contribution which vanishes as $Q^2\to \infty$. Revised model was critically updated and compared to the presently available data.

   hep-phPLB(2022)·6 citations
5. 05*

   Searching for extra Higgs bosons via $pp\to H,A\to \tau \mu ,\tau \tau$ at the Large Hadron Collider

   Wei-shu Hou🇹🇼 · Rishabh Jain🇹🇼 · Chung Kao🇺🇸

   We extend heavy Higgs searches at the Large Hadron Collider for $H\to \tau \mu$ by CMS, and $H\to \tau \tau$ by ATLAS and CMS, to study discovery prospects of extra Higgs states in $pp\to H,A\to \tau \mu ,\tau \tau$ with $e\mu +E_T$ and $j_{\tau }\mu +E_T$ final states, where $j_{\tau }=\pi ,\rho ,a_1$ and $E_T$ is missing transverse energy. In a general two Higgs doublet model without $Z_2$ symmetry, extra Yukawa couplings ${\rho }_{\tau \tau }$ and ${\rho }_{\tau \mu }$ can drive $H,A\to \tau \tau$ and $\tau \mu$ channels at hadron colliders, following gluon-gluon fusion production with extra ${\rho }_{tt}$ couplings. The light Higgs boson $h(125)$ is found to resemble closely the Standard Model Higgs boson; in the alignment limit of $\cos \gamma \to 0$ for $h$--$H$ mixing, flavor changing neutral Higgs couplings such as $h\to \tau \mu$ are naturally suppressed, but the couplings of the heavier $H$ is optimized by $\sin \gamma \to 1$. We define various signal regions for $H,A\to \tau \mu$ and $\tau \tau$ and evaluate physics backgrounds from dominant processes with realistic acceptance cuts and tagging efficiencies. Two different studies are presented. We first perform a parton level study without any hadronization and with minimal detector smearing. We then include hadronization using PYTHIA 8.2 and fast detector simulation using DELPHES to give event level simulation. Results for $\sqrt{s}=13$ TeV appear promising, which we extend further to $\sqrt{s}=14$ TeV for the High Luminosity LHC.

   hep-phhep-exEPJC(2023)·7 citations
6. 06*

   An estimation of non-valence contributions to form factors of heavy-light mesons

   María Gómez-Rocha🇪🇸 · Oliver Heger🇦🇹 · Wolfgang Schweiger🇦🇹

   We study the influence of non-valence quark-pair contributions in weak transition form factors of heavy-light mesons. Form factors are first calculated for spacelike momentum transfers in a reference frame where such contributions are suppressed. Analytic continuation to the timelike region and a comparison with the direct decay calculation, done with pure valence degrees of freedom, provides an estimate of the role that quark-pair contributions may play. We use the point form of relativistic quantum mechanics, which is particularly useful when treating heavy-light systems.

   hep-phRev.Mex.Fis.Suppl.(2022)·0 citations
7. 07*

   Radiative corrections to elastic muon-proton scattering at low momentum transfers

   Norbert Kaiser🇩🇪 · Yong-Hui Lin🇩🇪 · Ulf-G. Meißner🇩🇪

   We systematically calculate the radiative corrections of order $\alpha /\pi$ to elastic muon-proton scattering at low momentum transfers. These include vacuum polarization, photon-loop form factors of the muon and the proton, two-photon exchange corrections and soft photon radiation. In particular, we discuss these corrections for the kinematics of the upcomimg AMBER experiment with a $100$GeV muon beam energy. It is found that for the ratio to the Born cross section, only the minor terms from the photon-loop form factors of the proton and two-photon exchange depend on the proton structure predetermined by the strong interactions. Since a prominent role among the radiative corrections is played by soft photon radiation, the calculation of the bremsstrahlung process $\mu p\to \mu p\gamma$ should be extended beyond the soft photon approximation and tailored to the specific experimental conditions.

   hep-phhep-exnucl-exnucl-thPRD(2022)·9 citations
8. 08*

   Leptonic scalar portal: Origin of muon $g-2$ anomaly and dark matter?

   S.N. Gninenko🇷🇺 · N.V. Krasnikov🇷🇺

   We present a model explaining both the 4.2 $\sigma$ muon $g-2$ anomaly and the relic density of dark matter (DM) in which DM interacts with the Standard Model (SM) via a scalar portal boson $\phi$ carrying both dark and SM leptonic numbers, and mediating a nondiagonal interaction between the electron and muon that allows $e\leftrightarrow \mu$ transitions. The $\phi$ could be produced in high-energy electron scattering off a target nuclei in the reaction $eZ\to \mu Z\phi$ followed by the prompt invisible decay $\phi \to$~DM particles and searched for in events with large missing energy accompanied by a single outgoing muon in the final state. Interestingly, several events with a similar signature have been observed in a data sample of $\simeq 3\times 10^{11}$ electrons on target collected during 2016-2018 for the search for light dark matter in the NA64 experiment at the CERN SPS [PRL {\bf 123}, 121801 (2019)]. Attributing so far these events to background allows us to set first constraints on the $\phi$ mass and couplings while leaving at the same time decisively probing the origin of these events and a large fraction of the remaining parameter space to a near exiting future with the upgraded NA64 detector or other planned experiments.

   hep-phhep-exPRD(2022)·19 citations
9. 09*

   Reappraisal of the minimal flavoured $Z^{\prime }$ scenario

   Tirtha Sankar Ray🇮🇳 · Avirup Shaw🇮🇳

   Recent results from the intensity frontier indicate the tantalizing possibility of violation in lepton flavour universality. In light of this we revisit the minimal phenomenological $Z^{\prime }$ model taking in account both vectorial and axial-vectorial flavour violating couplings to the charged leptons. We make a systematic study to identify the minimal framework that can simultaneously explain the recent results on anomalous magnetic moment of muon and electron while remaining in consonance with $R_{K^{(\ast )}}$, $B_s^0-\overline{B_s^0}$ mixing and angular observables in the $B^{+}\to K^{+\ast }{\mu }^{+}{\mu }^{-}$ channel reported by the LHCb collaboration. We demonstrate that the neutrino trident data imply a further ${\mathrm{SU}(2)}_L$ violation in the leptonic couplings of the exotic $Z^{\prime }$.

   hep-phNPB(2023)·3 citations
10. 10*

    u-Channel Color Transparency Observables

    G.M. Huber🇨🇦 · W.B. Li🇺🇸 · W. Cosyn🇺🇸 · B. Pire🇫🇷

    We propose to study the onset of color transparency in hard exclusive reactions in the backward regime. Guided by the encouraging JLab results on backward pion and omega electro-production data at moderate Q^2, which may be interpreted as the signal of an early scaling regime where the scattering amplitude factorizes in a hard coefficient function convoluted with nucleon to meson transition distribution amplitudes, we show that the study of these channels on nuclear targets opens a new opportunity to test the appearance of nuclear color transparency for a fast moving nucleon.

    hep-phnucl-exnucl-thMDPI Physics(2022)·13 citations
11. 11*

    Neutrino astronomy as a probe of physics beyond the Standard Model: decay of sub-MeV $B$-$L$ gauge boson dark matter

    Weikang Lin🇨🇳 · Luca Visinelli🇨🇳 · Donglian Xu🇨🇳 · Tsutomu T. Yanagida🇨🇳

    The $U(1{)}_{B\text{–}L}$ symmetry, the essential component in the seesaw mechanism and leptogenesis, is naturally equipped with a massive gauge boson. If this gauge boson is the dark matter, the scenario consistent with the seesaw mechanism predicts the gauge coupling to be of the order of $\mathcal{O}(10^{-19})$ for masses $\lesssim 1$ MeV, dominantly decaying into active neutrinos. We stress and explore the important role of astrophysical neutrinos of energies from $\mathcal{O}(1)$ keV to $\sim 1$ MeV in testing the well-motivated $B$-$L$ symmetry extension to the Standard Model, which has been missed in the literature to date. Compared to other dark matter models, the neutrino flux in the sub-MeV energy range is a unique prediction in our setup and, once detected, would serve as a smoking gun for the existence of this $B$-$L$ gauge boson and its role as the dark matter particle, opening new windows to tackle cosmological and astrophysical conundra.

    hep-phastro-ph.COPRD(2022)·18 citations
12. 12*

    High-energy colliders as a probe of neutrino properties

    Sanjoy Mandal🇰🇷 · O. G. Miranda🇲🇽 · G. Sanchez Garcia🇲🇽 · J. W. F. Valle🇪🇸 · Xun-Jie Xu🇨🇳

    The mediators of neutrino mass generation can provide a probe of neutrino properties at the next round of high-energy hadron (FCC-hh) and lepton colliders (FCC-ee/ILC/CEPC/CLIC). We show how the decays of the Higgs triplet scalars mediating the simplest seesaw mechanism can shed light on the neutrino mass scale and mass-ordering, as well as the atmospheric octant. Four-lepton signatures at the high-energy frontier may provide the discovery-site for charged lepton flavour non-conservation in nature, rather than low-energy intensity frontier experiments.

    hep-phhep-exPLB(2022)·16 citations
13. 13*

    Optimising hadronic collider simulations using amplitude neural networks

    Ryan Moodie🇬🇧

    Precision phenomenological studies of high-multiplicity scattering processes at collider experiments present a substantial theoretical challenge and are vitally important ingredients in experimental measurements. Machine learning technology has the potential to dramatically optimise simulations for complicated final states. We investigate the use of neural networks to approximate matrix elements, studying the case of loop-induced diphoton production through gluon fusion. We train neural network models on one-loop amplitudes from the NJet C++ library and interface them with the Sherpa Monte Carlo event generator to provide the matrix element within a realistic hadronic collider simulation. Computing some standard observables with the models and comparing to conventional techniques, we find excellent agreement in the distributions and a reduced total simulation time by a factor of thirty.

    hep-phcs.AIcs.LGJ.Phys.Conf.Ser.(2023)·3 citations
14. 14*

    Single top production via FCNC couplings at an $e^{-}{e}^{+}$ collider with center-of-mass energy $\sqrt{s}=240$ GeV

    M. A. Arroyo-Ureña🇲🇽 · J. Lorenzo Díaz-Cruz🇲🇽 · R. Gaitán🇲🇽 · J.H. Montes de Oca🇲🇽 · T. A. Valencia-Pérez🇲🇽

    Aspects of top quark physics can be studied at a future Circular Electron-Positron Collider (CEPC). In particular, Flavor-Changing Neutral Current interactions (FCNC) of the top quark can be studied even with a center-of-mass energy from $\sqrt{s}\gtrsim m_t$ to $\sqrt{s}=240$ GeV, through the production a single top quark in association with a charm quark, which can arise in several scenarios of new physics. We explore here this signal within the Left-Right Mirror Model, which is a Left-Right model that includes mirror fermions; this model is motivated as a possible solution to the strong CP problem and by its rich phenomenology. We find that for particular scenarios of the model parameters, which are in agreement with the most up-to-date experimental constraints, the signal coming from the process $e^{+}{e}^{-}\to V\to tc$ ($V=Z,Z^{\prime }$) provide a detectable signal and thus it can give evidence for FCNC interactions; in these scenarios the mass of a new neutral gauge boson can be as high as $m_{Z^{\prime }}=7$ TeV.

    hep-phEur.Phys.J.Plus(2022)·0 citations
15. 15*

    A Strongly First-Order Electroweak Phase Transition from Loryons

    Ian Banta🇺🇸

    We study the effect of BSM particles receiving most of their mass from their coupling to the Higgs boson ("Loryons") on the electroweak phase transition. The existence of BSM Loryons would imply that electroweak symmetry must be non-linearly realized in the effective theory of the Standard Model. Since, by definition, Loryons have a significant coupling to the Higgs, they are expected to have a significant effect on the Higgs effective potential and thereby the electroweak phase transition. We show that the BSM Loryon parameter space viable under current experimental and theoretical constraints overlaps heavily with the parameter space in which a strongly first-order phase transition is predicted. The portion of the experimentally allowed parameter space which gives a strongly first-order phase transition is significantly larger for Loryons as compared to non-Loryons.

    hep-phJHEP(2022)·20 citations
16. 16*

    Full off-shell predictions and $b$-jet definitions for $t\bar{t}b\bar{b}$ at NLO in QCD

    Michele Lupattelli🇩🇪

    In this proceeding we present predictions for the complete NLO QCD corrections to the production of $t\bar{t}b\bar{b}$ in the dilepton decay channel of the top quark at the LHC with $\sqrt{s}=13$ TeV. The calculation is performed considering all the full off-shell effects. Moreover, the various sources of uncertainty for this process are studied in detail. We then compare these predictions to experimental measurements. We additionally investigate the impact of the $b$-quark initiated subprocesses.

    hep-ph0 citations
17. 17*

    Electromagnetic and strong isospin breaking in light meson masses

    Ángel S. Miramontes🇲🇽 · Reinhard Alkofer🇦🇹 · Christian S. Fischer🇩🇪 · Hèlios Sanchis-Alepuz🇦🇹

    We study electromagnetic as well as strong isospin breaking effects in the isospin mass splittings of light pseudoscalar and vector mesons. To this end we employ a coupled system of quark Dyson-Schwinger and meson Bethe-Salpeter equations whose interaction kernels contain gluon, pion and photon exchange interactions. In bound states, QCD-induced isospin breaking is manifest on different levels. On the one hand, a different explicit up- and down-quark mass directly affects the propagators of the constituent quarks. On the other hand, it leads to different interaction kernels within the isospin multiplets. In addition, electromagnetic isospin breaking is induced via a photon exchange diagram. Using the kaon iso-doublet and the charged pion masses as input to determine the up, down and strange quark masses we find for the pion, kaon and rho meson mass splittings different patterns each. In particular, our results provide evidence that the effects from two sources of mass splittings, the different quark masses and the different quark charges, do not add up linearly.

    hep-phhep-latnucl-thPLB(2022)·12 citations
18. 18*

    Quark and gluon form factors in four-loop QCD

    Roman N. Lee🇷🇺 · Andreas von Manteuffel🇺🇸 · Robert M. Schabinger🇺🇸 · Alexander V. Smirnov🇷🇺 · Vladimir A. Smirnov🇷🇺 · Matthias Steinhauser🇩🇪

    We compute the photon-quark and Higgs-gluon form factors to four-loop order within massless perturbative Quantum Chromodynamics. Our results constitute ready-to-use building blocks for N${}^4$LO cross sections for Drell-Yan processes and gluon-fusion Higgs boson production at the LHC. We present complete analytic expressions for both form factors and show several of the most complicated master integrals.

    hep-phhep-thPRL(2022)·89 citations
19. 19*

    The LPM Effect in sequential bremsstrahlung: $1/N_c^2$ corrections

    Peter Arnold🇺🇸 · Omar Elgedawy🇺🇸

    An important question concerning in-medium high-energy parton showers in a quark-gluon plasma or other QCD medium is whether consecutive splittings of the partons in a given shower can be treated as quantum mechanically independent, or whether the formation times for two consecutive splittings instead have significant overlap. Various previous calculations of the effect of overlapping formation times have either (i) restricted attention to a soft bremsstrahlung limit, or else (ii) used the large-$N_c$ limit (where $N_c=3$ is the number of quark colors). In this paper, we make a first study of the accuracy of the large-$N_c$ limit used by those calculations of overlap effects that avoid a soft bremsstrahlung approximation. Specifically, we calculate the $1/N_c^2$ correction to previous $N_c=\infty$ results for overlap $g\to gg\to ggg$ of two consecutive gluon splittings $g\to gg$. At order $1/N_c^2$, there is interesting and non-trivial color dynamics that must be accounted for during the overlap of the formation times.

    hep-phnucl-thJHEP(2022)·12 citations
20. 20*

    Study of the four-body decays $B_S^0\to \pi \pi \pi \pi$ in the perturbative QCD approach

    Hui-Qin Liang🇨🇳 · Xian-Qiao Yu🇨🇳

    In this work, we analyse the CP-averaged branching ratios and direct CP-violating asymmetries of the four-body decays B_{S} \rightarrow \pi\pi\pi\pi decay from the S-wave resonances, f_{0}(980) and f_{0}(500) and P-wave resonances, \rho(770) by introducing the S-wave and P-wave \pi\pi distribution amplitudes within the framework of the perturbative QCD approach. We also calculate branching ratios of the two-body decays B^{0}_{S}\rightarrow\rho^{0}\rho^{0}, B^{0}_{S}\rightarrow\rho^{+}\rho^{-} from the corresponding quasi-two-body decays models and compare our results with those obtained in previous perturbative QCD approach, QCD factorization approach and FAT approach, it is found that the predictions are consistent with present data within errors. The branching ratios of our calculations for the four-body decays B_{S}\rightarrow \pi\pi\pi\pi are at the order of the 10^{-7}. For the CP-violating asymmetries, we found that CP-violating asymmetry can be enhanced largely by the \rho-\omega mixing resonances when \pi\pi pairs masses are in the vicinity of \omega resonance.

    hep-phPRD(2022)·11 citations
21. 21*

    Vortex solutions in the presence of Dark Portals

    Paola Arias🇨🇱 · Ariel Arza🇷🇺 · Fidel A. Schaposnik🇦🇷 · Diego Vargas-Arancibia🇨🇱 · Moira Venegas🇨🇱

    The existence of hidden sectors weakly coupled to the visible one has been extensively studied as a way to extend the Standard Model (SM) and to provide a good dark matter candidate. In this work we analyze two models in which gauge and scalar hidden fields interact with the visible sector which, for simplicity we take as an Abelian Higgs model. In one of them, the hidden sector consists of an uncharged scalar. The connection with the visible Abelian Higgs sector is in this case provided by the interaction between the scalars in the two sectors and also by the coupling between the hidden scalar and the visible squared field strength. This model can be seen as an extension of previously studied ones both in high energy and in condensed matter physics and the solutions that we find indicate that it could be relevant in connection to establishing the dark matter relic density. In the second model, both sectors correspond to spontaneously broken gauge theories and hence they feature classical vortex solutions. Introducing three different portals between the two sectors, we analyze the dependence of the model dynamics on the portal parameters and discuss the physical implications in connection with dark matter and gravitational radiation issues.

    ↳ hep-thhep-phInt.J.Mod.Phys.A(2022)·7 citations
22. 22*

    Photo- and Electrocouplings of Nucleon Resonances

    Victor I. Mokeev🇺🇸 · Daniel S. Carman🇺🇸

    Advances in the exploration of the spectrum and structure of the excited states of the nucleon from experiments with electromagnetic probes on proton targets are presented. Impressive progress has been achieved in the studies of exclusive meson photoproduction in experiments with continuous electron beams and with detectors of almost $4\pi$ acceptance. The high-quality data, coupled with the advances in the amplitude analyses of exclusive photo- and hadroproduction data, allow for the observation of several long-awaited new baryon states known previously as the ``missing" resonances. Studies of exclusive meson electroproduction in the resonance region with the CLAS detector at JLab have provided the dominant part of the available world information on exclusive meson electroproduction observables. These data offer unique information on the structure of most well-established excited nucleon states in the mass region up to 1.8~GeV in terms of the evolution of their electroexcitation amplitudes with momentum transfer of the virtual photon. We discuss the impact of these results on the insight into the strong interaction dynamics that underlie the generation of the full spectrum of nucleon resonances of distinctively different structure. These results shed light on the emergence of hadron mass, which is one of the most important and still open problems in the Standard Model. The extension of the nucleon resonance studies in the experiments of the 12-GeV era at JLab with the CLAS12 detector are outlined.

    ↳ nucl-exhep-phFew Body Syst.(2022)·40 citations
23. 23*

    Anthropic constraint on transient variations of fundamental constants

    Vsevolod D. Dergachev · Hoang Bao Tran Tan🇺🇸 · Sergey A. Varganov · Andrei Derevianko🇺🇸

    The anthropic principle implies that life can emerge and be sustained only in a narrow range of values of fundamental constants. Here we show that anthropic arguments can set powerful constraints on {\em transient} variations of the fine-structure constant $\alpha$ over the past 4 billion years since the appearance of lifeforms on Earth. We argue that the passage through Earth of a macroscopic dark matter clump with a value of $\alpha$ inside differing substantially from its nominal value would make Earth uninhabitable. We demonstrate that in the regime of extreme variation of $\alpha$, the periodic table of elements is truncated, water fails to serve as a universal solvent, and protons become unstable. Thereby, the anthropic principle constrains the likelihood of such encounters on a 4-billion-year timescale. This enables us to improve existing astrophysical bounds on certain dark matter model couplings by several orders of magnitude.

    ↳ physics.atom-phastro-ph.COhep-phphysics.chem-ph+10 citations
24. 24*

    PKS 1424+240: yet another masquerading BL Lac object as a possible IceCube neutrino source

    P. Padovani🇩🇪 · B. Boccardi🇩🇪 · R. Falomo🇮🇹 · P. Giommi🇮🇹

    We show that the blazar PKS 1424+240, which has been recently associated by IceCube with a neutrino excess at the $3.3\sigma$ level together with three other sources, is similar to the first plausible non-stellar neutrino source, TXS 0506+056, in being also a masquerading BL Lac object, i.e., intrinsically a flat-spectrum radio quasar with hidden broad lines and a standard accretion disk. We point out that these two sources share other properties, including spectral energy distribution, high powers, parsec scale properties, and possibly radio morphology. We speculate that the relatively rare combination of proton-loaded jets, possibly typical of high-excitation sources, and efficient particle acceleration processes, related to their relatively high synchrotron peak frequencies, might favour neutrino production in these two sources. GB6 J1542+6129, which has also recently appeared twice in a list of IceCube associations, seems also to belong to this rare blazar sub-class, which includes at most ~ 20 Fermi-4LAC blazars.

    ↳ astro-ph.HEastro-ph.GAhep-exhep-phMNRAS(2022)·49 citations
25. 25*

    Measurement of the H to ZZ branching fraction at 350 GeV and 3 TeV CLIC

    N. Vukašinović🇷🇸 · I. Božović-Jelisavčić🇷🇸 · G. Kačarević🇷🇸 · M. Radulović🇷🇸 · J. Stevanović🇷🇸 · G. Milutinović-Dumbelović🇷🇸 · T. Agatonović-Jovin🇷🇸 · I. Smiljanić🇷🇸

    In this paper we investigate the prospects for measuring the branching fraction of the Standard Model Higgs boson decay into a pair of $Z$ bosons at the future Compact Linear Collider (CLIC) at 350 GeV and 3 TeV centre-of-mass energies. Studies are performed using a detailed simulation of the detector for CLIC, taking into consideration all relevant physics and beam-induced background processes. It is shown that the product of the Higgs production cross-section and the branching fraction BR($H\to Z{Z}^{\ast }$) can be measured with a relative statistical uncertainty of 20% (3.0%) at a centre-of-mass energy of 350 GeV (3 TeV) using semileptonic final states, assuming an integrated luminosity of 1 ab${}^{-1}$ (5 ab${}^{-1}$).

    ↳ hep-exhep-phphysics.acc-phPRD(2022)·4 citations
26. 26*

    Mass gap for a monopole interacting with different nonlinear spinor fields

    Vladimir Dzhunushaliev🇰🇿 · Vladimir Folomeev🇰🇬 · Aizhan Abdykaliyeva🇰🇿 · Symbat Khussainova🇰🇿 · Akbota Temirova🇰🇿

    We study the properties of the mass gap for monopole solutions in SU(2) Yang-Mills theory with a source of the non-Abelian gauge field in the form of a spinor field described by the nonlinear Dirac equation. Different types of nonlinearities parameterized by the parameter $\lambda$ are under consideration. It is shown that for the range of values of this parameter studied in the present paper the value of the mass gap depends monotonically on this parameter, and the position of the mass gap does not practically depend on $\lambda$.

    ↳ hep-thhep-ph0 citations
27. 27*

    Analyzing the Hubble tension through hidden sector dynamics in the early universe

    Amin Aboubrahim🇩🇪 · Michael Klasen🇩🇪 · Pran Nath🇺🇸

    The recent analysis from the SH0ES Collaboration has confirmed the existence of a Hubble tension between measurements at high redshift ($z>1000$) and at low redshift ($z<1$) at the $5\sigma$ level with the low redshift measurement giving a higher value. In this work we propose a particle physics model that can help alleviate the Hubble tension via an out-of-equilibrium hidden sector coupled to the visible sector. The particles that populate the dark sector consist of a dark fermion, which acts as dark matter, a dark photon, a massive scalar and a massless pseudo-scalar. Assuming no initial population of particles in the dark sector, feeble couplings between the visible and the hidden sectors via kinetic mixing populate the dark sector even though the number densities of hidden sector particles never reach their equilibrium distribution and the two sectors remain at different temperatures. A cosmologically consistent analysis is presented where a correlated evolution of the visible and the hidden sectors with coupled Boltzmann equations involving two temperatures, one for the visible sector and the other for the hidden sector, is carried out. The relic density of the dark matter constituted of dark fermions is computed in this two-temperature formalism. As a consequence, BBN predictions are upheld with a minimal contribution to $\Delta N_{\mathrm{eff}}$. However, the out-of-equilibrium decay of the massive scalar to the massless pseudo-scalar close to the recombination time causes an increase in $\Delta N_{\mathrm{eff}}$ that can help weaken the Hubble tension.

    ↳ astro-ph.COhep-phJCAP(2022)·29 citations
28. 28*

    Opportunities for studying $C$-even resonances at 3-12 GeV photon collider

    K.I. Beloborodov (1 and 2)🇷🇺 · T.A. Kharlamova (1 and 2)🇷🇺 · G. Moortgat-pick (3 and 4)🇩🇪 · V.I. Telnov (1 and 2) ((1) Budker Institute of Nuclear Physics, Novosibirsk, Russia, (2) Novosibirsk State University, Novosibirsk, Russia, (3) II. Inst. f. Theoret. Physics, University of Hamburg, Hamburg, Germany, (4) DESY, Hamburg, Germany)🇷🇺

    Recently, a $\gamma \gamma$ collider based on the existing 17.5 GeV linac of the European XFEL has been proposed. High-energy photons will be generated by Compton scattering of laser photons with a wavelength of 0.5-1 $\mu$m on electrons. Such a photon collider covers the range of invariant masses $W_{\gamma \gamma }<12$ GeV. The physics program includes spectroscopy of $C$-even resonances ($c$-, $b$-quarkonia, 4-quark states, glueballs) in various $J^P$ states. Variable circular and linear polarizations will help in determining the quantum numbers. In this paper, we present a summary of measured and predicted two-photon widths of various resonances in the mass region 3-12 GeV and investigate the experimental possibility of observing these heavy two-photon resonances under the conditions of a large multi-hadron background. Registration of all final particles is assumed. The minimum values of ${\Gamma }_{\gamma \gamma }(W)$ are obtained at which resonances can be detected at a $5\sigma$ confidence level in one year of operation.

    ↳ hep-exhep-phphysics.acc-phEPJC(2023)·4 citations
29. 29*

    4D dS vacua from AdS vacua of type IIB string theory and AdS distance conjecture

    Cao H. Nam🇻🇳

    In order for string theory to be made compatible with the low-energy observations of a positive cosmological constant, there have been attempts to construct dS vacua in string theory which are particularly difficult to realize. Instead of attempting to find de Sitter (dS) vacuum solutions, we point to a new way to make string theory consistent with low-energy dS cosmology. In this way, string theory lives in an anti-de Sitter (AdS) vacuum (which is simple to construct) that exists only in the high-energy regime; however, as going to the low-energy scales where the heavy string excitations and Kaluza-Klein modes are integrated out, we show that the effective picture of string theory in lower dimensions would exhibit a 4D dS vacuum without needing to add additional structures such as anti-D3 branes. Additionally, we point to evidence from bottom-up physics for the strong version of the AdS distance conjecture realized from AdS vacua in string theory. This evidence hence supports the sharpening of the AdS distance conjecture as one of the universal features of quantum gravity.

    ↳ hep-thgr-qchep-phPRD(2023)·9 citations
30. 30*

    Analytic thin wall false vacuum decay rate

    Aleksandar Ivanov🇸🇮 · Marco Matteini🇸🇮 · Miha Nemevšek🇸🇮 · Lorenzo Ubaldi🇮🇹

    We derive a closed-form false vacuum decay rate at one loop in the thin wall limit, where the true and false vacua are nearly degenerate. We obtain the bounce configuration in $D$ dimensions, together with the Euclidean action with a higher order correction, counter-terms and renormalization group running. We extract the functional determinant via the Gel'fand-Yaglom theorem for low and generic orbital multipoles. The negative and zero eigenvalues appear for low multipoles and the translational zeroes are removed. We compute the fluctuations for generic multipoles, multiply and regulate the orbital modes. We find an explicit finite renormalized decay rate in $D=3,4$ and give a closed-form expression for the finite functional determinant in any dimension.

    ↳ hep-thastro-ph.HEhep-phJHEP(2022)·29 citations
31. 31*

    Towards Classification of $\mathcal{N}=1$ and $\mathcal{N}=0$ Flipped $SU(5)$ Asymmetric ${\mathbb{Z}}_2\times {\mathbb{Z}}_2$ Heterotic String Orbifolds

    Alon E. Faraggi🇬🇧 · Viktor G. Matyas🇬🇧 · Benjamin Percival🇬🇧

    The free fermionic classification method provides a powerful tool to investigate string vacua, which led to the discovery of spinor--vector duality and exophobic string models. We extend the classification methodology to both $\mathcal{N}=1$ and $\mathcal{N}=0$ Flipped $SU(5)$ ${\mathbb{Z}}_2\times {\mathbb{Z}}_2$ heterotic string orbifolds with asymmetric shifts. The impact of the asymmetric assignments on the phenomenological characteristics of these models is investigated. Of particular interest is the analysis of untwisted moduli fixing for various choices of asymmetric boundary conditions. Two classes of vacua with different characteristics are systematically investigated with help from SAT/SMT algorithms, which are shown to increase search efficiency by up to two orders of magnitude, as well as providing useful tools to find contradictions between various phenomenological criteria. The general form of the partition function for the space of models is explained and given for two specific example models for different choices of asymmetric boundary conditions. Additionally, the distribution of one-loop cosmological constant contributions for samples in the two different classes of models are depicted and discussed.

    ↳ hep-thhep-phPRD(2022)·18 citations
32. 32*

    Symmetries in subatomic six-quark fermions

    J.D. Vergados🇬🇷 · D. Strottman🇺🇸

    The evidence of the existence of tetra-quark meson and penta-quark fermion systems has revived interest in the hunt of other multi-quark systems. We explore the possibility of six-quark cluster configurations with the two nucleon spin-isospin quantum numbers existing in the nuclear medium. The investigation of such clusters is feasible if one exploits all the symmetries involved, in particular orbital, color-spin $SU(6{)}_{cs}$ and isospin SU(2). We investigate whether such clusters contribute to neutrinoless double-beta decay mediated by heavy neutrinos or other exotic particles, since in conventional nuclear physics the relevant nuclear matrix elements are suppressed due to the presence of the nuclear hard core.

    ↳ nucl-thhep-ph0 citations
33. 33*

    Cosmic Birefringence: Cross-Spectra and Cross-Bispectra with CMB Anisotropies

    Alessandro Greco (Physics and Astronomy Dept. and INFN, Padova, ITALY)🇮🇹 · Nicola Bartolo (Physics and Astronomy Dept. and INFN and INAF, Padova, ITALY)🇮🇹 · Alessandro Gruppuso (INAF and INFN, Bologna, ITALY)🇮🇹

    Parity-violating extensions of Maxwell electromagnetism induce a rotation of the linear polarization plane of photons during propagation. This effect, known as cosmic birefringence, impacts on the Cosmic Microwave Background (CMB) observations producing a mixing of $E$ and $B$ polarization modes which is otherwise null in the standard scenario. Such an effect is naturally parametrized by a rotation angle which can be written as the sum of an isotropic component ${\alpha }_0$ and an anisotropic one $\delta \alpha (\hat{\mathbf{n}})$. In this paper we compute angular power spectra and bispectra involving $\delta \alpha$ and the CMB temperature and polarization maps. In particular, contrarily to what happens for the cross-spectra, we show that even in absence of primordial cross-correlations between the anisotropic birefringence angle and the CMB maps, there exist non-vanishing three-point correlation functions carrying signatures of parity-breaking physics. Furthermore, we find that such angular bispectra still survive in a regime of purely anisotropic cosmic birefringence, which corresponds to the conservative case of having ${\alpha }_0=0$. These bispectra represent an additional observable aimed at studying cosmic birefringence and its parity-violating nature beyond power spectrum analyses. They provide also a way to perform consistency checks for specific models of cosmic birefringence. Moreover, we estimate that among all the possible birefringent bispectra, $⟨\delta \alpha TB⟩$ and $⟨\delta \alpha EB⟩$ are the ones which contain the largest signal-to-noise ratio. Once the cosmic birefringence signal is taken to be at the level of current constraints, we show that these bispectra are within reach of future CMB experiments, as LiteBIRD.

    ↳ astro-ph.COgr-qchep-phhep-thJCAP(2022)·32 citations
34. 34*

    Correlating Gravitational Wave and Gamma-ray Signals from Primordial Black Holes

    Kaustubh Agashe🇺🇸 · Jae Hyeok Chang🇺🇸 · Steven J. Clark🇺🇸 · Bhaskar Dutta🇺🇸 · Yuhsin Tsai🇺🇸 · Tao Xu🇮🇱

    Asteroid-mass primordial black holes (PBH) can explain the observed dark matter abundance while being consistent with the current indirect detection constraints. These PBH can produce gamma-ray signals from Hawking radiation that are within the sensitivity of future measurements by the AMEGO and e-ASTROGAM experiments. PBH which give rise to such observable gamma-ray signals have a cosmic origin from large primordial curvature fluctuations. There must then be a companion, stochastic gravitational wave (GW) background produced by the same curvature fluctuations. We demonstrate that the resulting GW signals will be well within the sensitivity of future detectors such as LISA, DECIGO, BBO, and the Einstein Telescope. The multi-messenger signal from the observed gamma-rays and GW will allow a precise measurement of the primordial curvature perturbation that produces the PBH. Indeed, we argue that the resulting correlation between the two types of observations can provide a smoking-gun signal of PBH.

    ↳ astro-ph.COastro-ph.HEhep-phPRD(2022)·23 citations
35. 35*

    Non-standard neutrino cosmology dilutes the lensing anomaly

    Ivan Esteban🇺🇸 · Olga Mena🇪🇸 · Jordi Salvado🇪🇸

    Despite the impressive success of the standard cosmological model, several anomalies defy its triumph. Among them is the so-called lensing anomaly: the Planck satellite observes stronger CMB gravitational lensing than expected. The role of neutrinos in this anomaly has been mostly overlooked, despite their key role in CMB lensing, because in the standard scenario they tend to increase the tension. Here, we show that this strongly depends on the assumed neutrino equation of state. We demonstrate that if neutrinos have yet undiscovered long-range interactions, the lensing pattern is significantly affected, rendering the lensing anomaly as a statistical fluctuation. Our results thus open up a window to link anomalous CMB lensing with present and future cosmological, astrophysical, and laboratory measurements of neutrino properties.

    ↳ astro-ph.COhep-phPRD(2022)·20 citations
36. 36*

    Higgs-Dilaton Inflation in Einstein-Cartan gravity

    Matteo Piani🇵🇹 · Javier Rubio🇵🇹

    We study the phenomenology of the Higgs-Dilaton model in the context of Einstein-Cartan gravity, focusing on the separate impact of the Holst and Nieh-Yan terms on the inflationary observables. Using analytical and numerical techniques, we show the predictions of these scenarios to display an attractor-like behaviour intrinsically related to the curvature of the field-space manifold in the metric formulation of the theory. Beyond that, the analysis of the Nieh-Yan case reveals the existence of an additional attractor solution induced by a cubic pole in the inflaton kinetic term that becomes relevant at large dilaton couplings. This constitutes a unique feature of the Einstein-Cartan formulation as compared to the metric and Palatini counterparts.

    ↳ gr-qcastro-ph.COhep-phJCAP(2022)·46 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.