Mon·Jun 19, 2023Monday·June 19, 2023

1. 01*

   A decoherence explanation of the gallium neutrino anomaly

   Yasaman Farzan🇮🇷 · Thomas Schwetz🇩🇪

   Gallium radioactive source experiments have reported a neutrino-induced event rate about 20\% lower than expected with a high statistical significance. We present an explanation of this observation assuming quantum decoherence of the neutrinos in the gallium detectors at a scale of 2~m. This explanation is consistent with global data on neutrino oscillations, including solar neutrinos, if decoherence effects decrease quickly with energy, for instance with a power law $E_{\nu }^{-r}$ with $r\simeq 12$. Our proposal does not require the presence of sterile neutrinos but implies a modification of the standard quantum mechanical evolution equations for active neutrinos.

   hep-phhep-exSciPost Phys.(2023)·24 citations
2. 02*

   Non-perturbative effects for dark sectors with QCD portals

   Simone Biondini🇨🇭 · Talal Ahmed Chowdhury🇧🇩 · Shaikh Saad🇨🇭

   In this work, we consider a class of dark matter (DM) models where the DM does not directly interact with the Standard Model (SM) particles at the tree-level. Therefore, the coannihilation mechanism is crucial in achieving the correct DM relic abundance, which in turn requires the coannihilating partner to be close in mass to the actual DM particle. In our systematisation of the models' class, the mediator and the coannihilation partner are assumed to be charged under QCD interactions. This last feature calls for a scrutiny of non-perturbative effects, namely Sommerfeld factors and bound-state formation, on the annihilations of the colored partner. Such non-perturbative effects are illustrated with an example model comprising a scalar leptoquark mediator, a Dirac vector-like fermion coannihilation partner, and a singlet DM fermion. Phenomenological features of this model, namely DM direct and indirect detection prospects, collider implications, and impact on the muon anomalous magnetic moment, are discussed.

   hep-phJHEP(2023)·7 citations
3. 03*

   Primordial black hole superradiance and evaporation in the string axiverse

   Marco Calzà🇵🇹 · João G. Rosa🇵🇹 · Filipe Serrano🇵🇹

   In the string axiverse scenario, light primordial black holes may spin up due to the Hawking emission of a large number of light (sub-MeV) axions. We show that this may trigger superradiant instabilities associated with a heavier axion during the black holes' evolution, and study the coupled dynamics of superradiance and evaporation. We find, in particular, that the present black hole mass-spin distribution should follow the superradiance threshold condition for black hole masses below the value at which the superradiant cloud forms, for a given heavy axion mass. Furthermore, we show that the decay of the heavy axions within the superradiant cloud into photon pairs may lead to a distinctive line in the black hole's emission spectrum, superimposed on its electromagnetic Hawking emission.

   hep-phastro-ph.COgr-qcJHEP(2024)·45 citations
4. 04*

   Analytical Evaluation of Elastic Lepton-Proton Two-Photon Exchange in Chiral Perturbation Theory

   Poonam Choudhary · Udit Raha · Fred Myhrer · Dipankar Chakrabarti

   We present an exact evaluation of the two-photon exchange contribution to the elastic lepton-proton scattering process at low-energies using heavy baryon chiral perturbation theory. The evaluation is performed including next-to-leading order accuracy. This exact analytical evaluation contains all soft and hard two-photon exchanges and we identify the contributions missing in a soft-photon approximation approach. We evaluate the infrared divergent four-point box diagrams analytically using dimensional regularization. We also emphasize the differences between muon-proton and electron-proton scatterings relevant to the MUSE kinematics due to lepton mass differences.

   hep-phEPJA(2024)·11 citations
5. 05*

   Transverse momentum dependent factorization for SIDIS at next-to-leading power

   Simone Rodini🇫🇷 · Alexey Vladimirov🇪🇸

   The semi-inclusive deep-inelastic scattering (SIDIS) is the golden process for investigating the nucleon's transverse momentum-dependent (TMD) structure. We present the complete expression for SIDIS structure functions in the TMD factorization formalism at the next-to-leading power. All perturbative elements of the factorization theorem -- coefficient functions and evolution kernels -- are presented at one-loop accuracy. We found several differences with earlier derivations, which are due to accounting for nontrivial kinematics of the quark-gluon interference terms. As a side result, we present the definition and evolution of twist-three TMD fragmentation functions, including the leading-order evolution kernel.

   hep-phnucl-thPRD(2024)·30 citations
6. 06*

   Complementarity of $B\to K^{(\ast )}\mu \bar{\mu }$ and $B\to K^{(\ast )}+\mathrm{inv}$ for searches of GeV-scale Higgs-like scalars

   Maksym Ovchynnikov🇩🇪 · Michael A. Schmidt🇦🇺 · Thomas Schwetz🇩🇪

   The rare decays $B^{+}\to K^{+}\mu \bar{\mu }$ and $B^0\to K^{\ast 0}\mu \bar{\mu }$ provide the strongest constraints on the mixing of a light scalar with the Higgs boson for GeV-scale masses. The constraints sensitively depend on the branching ratio to muons. Additional decay channels like an invisible partial width may substantially weaken the constraints. This scenario will be probed at Belle II in $B\to K^{(\ast )}+\mathrm{inv}$. We illustrate the complementarity of scalar decays to muons and invisible decays using the currently available results of LHCb and BaBar. We provide two simple model realisations providing a sizeable invisible scalar width, one based on a real scalar and one based on a $U(1{)}_{B-L}$ gauge symmetry. In both examples the scalar decays into heavy neutral leptons which can be motivated by the seesaw mechanism for neutrino masses.

   hep-phhep-exEPJC(2023)·16 citations
7. 07*

   Glueball dark matter, precisely

   Pierluca Carenza🇸🇪 · Tassia Ferreira🇬🇧 · Roman Pasechnik🇸🇪 · Zhi-Wei Wang🇨🇳

   We delve deeper into the potential composition of dark matter as stable scalar glueballs from a confining dark $SU(N)$ gauge theory, focusing on $N=\{3,4,5\}$. To predict the relic abundance of glueballs for the various gauge groups and scenarios of thermalization of the dark gluon gas, we employ a thermal effective theory that accounts for the strong-coupling dynamics in agreement with lattice simulations. We compare our methodology with previous works and discuss the possible sources of discrepancy. The results are encouraging and show that glueballs can account for the totality of dark matter in many unconstrained scenarios with a phase transition scale $20$ MeV$\lesssim \Lambda \lesssim 10^{10}$ GeV, thus opening the possibility of exciting future studies.

   hep-phastro-ph.COhep-lathep-thPRD(2023)·26 citations
8. 08*

   Spontaneous Parity Violation

   Goran Senjanović🇩🇪 · Vladimir Tello🇮🇹

   We review here the central features of the idea of spontaneous breakdown of parity, in the context of its minimal realization, the Left-Right symmetric gauge theory.

   hep-phPoS(2024)·3 citations
9. 09*

   Probing general $U(1{)}^{\prime }$ models with non-universal lepton charges at FASER/FASER2, COHERENT and long-baseline oscillation experiments

   Tobias Felkl🇦🇺 · Tong Li🇨🇳 · Jiajun Liao🇨🇳 · Michael A. Schmidt🇦🇺

   The general anomaly-free $U(1{)}^{\prime }$ models allow non-universal lepton charges. We explore the sensitivities of FASER/FASER2, COHERENT and DUNE/T2HK precision experiments to the new gauge boson $Z^{\prime }$ and the new CP-even scalar $\varphi$. With non-universal lepton charges, distinctive reaches at FASER/FASER2 emerge in the regime of low $m_{Z^{\prime }}$ and small gauge coupling $g_{BL}$ for different $U(1{)}^{\prime }$ charge setups. The COHERENT experiment and the future long-baseline experiments DUNE/T2HK also provide complementary probes to the available parameter space. For $m_{\varphi }<2m_{Z^{\prime }}$, the search for the scalar $\varphi$ at FASER/FASER2 is sensitive to the mixing angle between the scalar singlet and the SM Higgs. In the case of $m_{\varphi }>2m_{Z^{\prime }}$, the kinematically allowed decay $\varphi \to Z^{\prime }{Z}^{\prime }$ changes the lifetime and decay rates of the scalar $\varphi$. The sensitivity reach highly depends on the $Z^{\prime }$ mass and the gauge coupling $g_{BL}$.

   hep-phhep-exJHEP(2023)·6 citations
10. 10*

    Two dark matter candidates in a doublet-triplet Higgs model

    Sheryl Melara-Duron🇲🇽 · R. Gaitán🇲🇽 · J. M. Lamprea🇲🇽

    We study a Standard Model extension that provides a bicomponent dark matter scenario as well as a mechanism for the generation of left-handed neutrino masses. We extend the Standard Model scalar sector by adding an inert $SU(2{)}_L$ doublet with hypercharge $Y=1/2$ and a triplet with hypercharge $Y=0$. These scalars provide dark matter candidates in two dark sectors stabilised by discrete symmetries. We consider the contribution of both candidates to the total relic abundance in order to recover the desert regions in their standard alone cases. In addition, we add an active scalar $SU(2{)}_L$ triplet with hypercharge $Y=1$ in order to generate light neutrino masses. We analyse the results of dark matter phenomenology for the model and the neutrino mass generation through the type-II seesaw mechanism.

    hep-phEur.Phys.J.Plus(2025)·1 citation
11. 11*

    Optomechanical dark matter instrument for direct detection

    Christopher G. Baker🇦🇺 · Warwick P. Bowen🇦🇺 · Peter Cox🇦🇺 · Matthew J. Dolan🇦🇺 · Maxim Goryachev🇦🇺 · Glen Harris🇦🇺

    We propose the Optomechanical Dark-matter INstrument (ODIN), based on a new method for the direct detection of low-mass dark matter. We consider dark matter interacting with superfluid helium in an optomechanical cavity. Using an effective field theory, we calculate the rate at which dark matter scatters off phonons in a highly populated, driven acoustic mode of the cavity. This scattering process deposits a phonon into a second acoustic mode in its ground state. The deposited phonon ($\mu$eV range) is then converted to a photon (eV range) via an optomechanical interaction with a pump laser. This photon can be efficiently detected, providing a means to sensitively probe keV scale dark matter. We provide realistic estimates of the backgrounds and discuss the technical challenges associated with such an experiment. We calculate projected limits on dark matter-nucleon interactions for dark matter masses ranging from 0.5 to 300 keV and estimate that a future device could probe cross-sections as low as $\mathcal{O}(10^{-32})$ cm${}^2$.

    hep-phhep-exphysics.ins-detquant-phPRD(2024)·22 citations
12. 12*

    Towards a Stability Analysis of Inhomogeneous Phases in QCD

    Theo F. Motta🇩🇪 · Julian Bernhardt🇩🇪 · Michael Buballa🇩🇪 · Christian S. Fischer🇩🇪

    The possible occurrence of crystalline or inhomogeneous phases in the QCD phase diagram at large chemical potential has been under investigation for over thirty years. Such phases are present in models of QCD such as the Gross-Neveu model in 1+1 dimensions, Nambu-Jona-Lasinio (NJL) and quark meson models. Yet, no unambiguous confirmation exists from actual QCD. In this work, we propose a new approach for a stability analysis that is based on the two-particle irreducible effective action and compatible with full QCD calculations within the framework of functional methods. As a first test, we reproduce a known NJL model result within this framework. We then discuss the additional difficulties which arise in QCD due to the non-locality of the quark self-energy and suggest a method to overcome them. As a proof of principle and as an illustration of the analysis, we consider the Wigner-Weyl solution of the quark Dyson-Schwinger equation (DSE) within a simple truncation of QCD in the chiral limit and analyse its stability against homogeneous chiral-symmetry breaking fluctuations. For temperatures above and below the tricritical point we find that the boundary of the instability region coincides well with the second-order phase boundary or the left spinodal, respectively, obtained from the direct solutions of the DSEs. Finally, we outline how this method can be generalized to study inhomogeneous fluctuations.

    hep-phnucl-thPRD(2023)·31 citations
13. 13*

    Leading $\Lambda$ production in future electron-proton colliders

    F. Carvalho🇧🇷 · V.P. Gonçalves🇩🇪 · K.P. Khemchandani🇧🇷 · F.S. Navarra🇧🇷 · D.S. Spiering🇧🇷 · A. Martínez Torres🇧🇷

    Leading $\Lambda$ (LL) production in $ep$ collisions at high energies is investigated using the color dipole formalism and taking into account the nonlinear QCD effects. In particular, the impact of the absorptive effects on the LL spectra are estimated considering the kinematical range that will be probed by the Electron Ion Collider (EIC) and by the Large Hadron electron Collider (LHeC). Our results indicate that the LL spectrum is strongly suppressed at small photon virtualities. These results suggest that absorptive effects are not negligible and should be taken into account in order to extract the kaon structure function from data on leading $\Lambda$ production.

    hep-phPRD(2023)·2 citations
14. 14*

    Sterile neutrinos, dark matter and Standard Model extended by right-handed neutrinos

    A.P. Serebrov🇷🇺 · R.M. Samoilov🇷🇺 · O.M. Zherebtsov🇷🇺 · N.S. Budanov🇷🇺

    Joint analysis of the results of the Neutrino-4 experiment and the data of the GALLEX, SAGE and BEST experiments confirms the parameters of neutrino oscillations declared by the Neutrino-4 experiment $(\Delta m_{14}^2=7.3{\text{eV}}^2$ and ${\sin }^{2}2{\theta }_{14}\approx 0.36)$ and increases the confidence level to $5.8\sigma$. Such a sterile neutrino thermalizes in cosmic plasma, contributes 5% to the energy density of the Universe, and can explain 15-20% of dark matter. It is discussed that the extension of the neutrino model by introducing two more heavy sterile neutrinos in accordance with the number of types of active neutrinos but with very small mixing angles to avoid thermalization will make it possible to explain the large-scale structure of the Universe and bring the contribution of sterile neutrinos to the dark matter of the Universe to the level of 27%. Sterile neutrinos are essentially right-handed neutrinos. The dynamic process of the dark matter generation, consisting of three right-handed neutrinos, is presented. Expansion of the Standard Model by introducing right-handed neutrinos seems possible. The scheme of masses and the scheme of mixing flavors are considered.

    hep-ph9 citations
15. 15*

    Diboson production in the SMEFT from gluon fusion

    Alejo N. Rossia🇬🇧 · Marion O. A. Thomas🇬🇧 · Eleni Vryonidou🇬🇧

    Precision measurements of diboson production at the LHC is an important probe of the limits of the Standard Model. The gluon-fusion channel of this process offers a connection between the Higgs and top sectors. We study in a systematic way gluon-induced diboson production in the Standard Model Effective Field Theory. We compute the amplitudes of double Higgs, double $Z/W$ and associated $ZH$ production at one loop and with up to one insertion of a dimension-6 operator. We study their high-energy limit and identify to which operators each channel could be most sensitive. To illustrate the relevance of these processes, we perform a phenomenological study of associated $ZH$ production. We show that for some top operators the gluon-induced channel can offer competitive sensitivity to constraints obtained from top quark production processes.

    hep-phJHEP(2023)·21 citations
16. 16*

    Scale dependence of the Kondo interaction in the functional renormalization group formalism

    Gergely Fejős🇭🇺 · Taro Kimura🇫🇷 · Zsolt Szép🇭🇺

    Scale evolution of interactions between a Weyl fermion and a heavy magnetic impurity is calculated non-perturbatively using the functional renormalization group technique. Using an expansion around the vanishing pairing gap, we derive the flow equations for all possible quartic couplings in the system. We find that contrary to conventional perturbation theory, the usual spin-spin isotropic interaction necessarily splits into two invariant parts during the scale evolution, which are fully allowed by the $SU(2)$ spin-rotation symmetry. We also find the existence of an infrared stable interacting fixed point, which can be responsible for intermediate-coupling screening effects. The calculation scheme presented here is rather general and expected to be easily applicable to various spin-spin-like interactions in fermionic systems.

    hep-phcond-mat.str-elPRB(2023)·0 citations
17. 17*

    The paradox of coherent photoproduction in incoherent interactions

    Spencer R. Klein🇺🇸

    The Good-Walker (GW) paradigm relates coherent and incoherent exclusive reactions to the average target configuration and its nucleonic and partonic fluctuations. In it, coherent photoproduction occurs when the target remains in the ground state, while, in incoherent photoproduction, the target breaks up. However, the GW paradigm fails to explain the observation of coherent vector meson photoproduction accompanied by nuclear breakup in ultra-peripheral collisions (UPCs) , and in peripheral relativistic heavy-ion collisions. In the latter, hundreds of particles can be created. This writeup will explore this paradox, and also present an alternate, semi-classical approach toward coherent production: adding the amplitudes with an appropriate propagator. The semi-classical approach explains the transverse momentum dependence of exclusive vector meson production in UPCs, but does not address the target final state. I will address these two approaches, and suggest possible future work to resolve the paradox \cite{Klein:2023zlf}.

    ↳ nucl-thhep-ph1 citation
18. 18*

    Open charm phenomenology with a multi-stage approach to relativistic heavy-ion collisions

    Mayank Singh🇺🇸 · Manu Kurian🇺🇸 · Sangyong Jeon🇨🇦 · Charles Gale🇨🇦

    We study open charm flavor observables in Pb+Pb collision at $\sqrt{s_{NN}}=2.76$ TeV within the MARTINI framework. The space-time expansion of the quark-gluon plasma is described using the hydrodynamical approach-MUSIC with IP-Glasma initial conditions. The model parameters, including the viscous coefficients, were obtained from a recent Bayesian model-to-data comparison. We evolve heavy quarks in this background using Langevin dynamics while incorporating their collisional and radiative processes in the medium. The sensitivity of charm observables to the IP-Glasma initial state, bulk evolution, and centrality of the collision is studied. We find that the elliptic flow of open charm flavor has a strong dependence on the fluctuating initial conditions in addition to the strength of the interaction of heavy quarks with the medium constituents. Within this framework, the nuclear suppression factor and elliptic flow of D-mesons act as efficient probes to study the initial stages of heavy-ion collisions, transport coefficients associated with QGP medium as well as heavy quark interactions.

    ↳ nucl-thhep-phPRC(2023)·28 citations
19. 19*

    JUNO sensitivity to the annihilation of MeV dark matter in the galactic halo

    JUNO Collaboration: Angel Abusleme · Thomas Adam · Shakeel Ahmad · Rizwan Ahmed · Sebastiano Aiello · Muhammad Akram · Abid Aleem · Tsagkarakis Alexandros · Fengpeng An · Qi An · Giuseppe Andronico · Nikolay Anfimov and 593 other authors

    We discuss JUNO sensitivity to the annihilation of MeV dark matter in the galactic halo via detecting inverse beta decay reactions of electron anti-neutrinos resulting from the annihilation. We study possible backgrounds to the signature, including the reactor neutrinos, diffuse supernova neutrino background, charged- and neutral-current interactions of atmospheric neutrinos, backgrounds from muon-induced fast neutrons and cosmogenic isotopes. A fiducial volume cut, as well as the pulse shape discrimination and the muon veto are applied to suppress the above backgrounds. It is shown that JUNO sensitivity to the thermally averaged dark matter annihilation rate in 10 years of exposure would be significantly better than the present-day best limit set by Super-Kamiokande and would be comparable to that expected by Hyper-Kamiokande.

    ↳ hep-exastro-ph.HEhep-phJCAP(2023)·25 citations
20. 20*

    Early-times Yang-Mills dynamics and the characterization of strongly interacting matter with statistical learning

    Matthew R. Heffernan🇨🇦 · Charles Gale🇨🇦 · Sangyong Jeon🇨🇦 · Jean-François Paquet🇺🇸

    In ultrarelativistic heavy-ion collisions, a plasma of deconfined quarks and gluons is formed within $1$ fm/c of the nuclei's impact. The complex dynamics of the collision before $\approx 1$ fm/c is often described with parametric models, which affect the predictivity of calculations. In this work, we perform a systematic analysis of LHC measurements from Pb-Pb collisions, by combining an \emph{ab-initio} model of the early stage of the collisions with a hydrodynamic model of the plasma. We obtain state-of-the-art constraints on the shear and bulk viscosity of quark-gluon plasma. We mitigate the additional cost of the ab-initio initial conditions by combining Bayesian model averaging with transfer learning, allowing us to account for important theoretical uncertainties in the hydrodynamics-to-hadron transition. We show that, despite the apparent strong constraints on the shear viscosity, metrics that balance the model's predictivity with its degree of agreement with data do not prefer a temperature-dependent specific shear viscosity over a constant value. We validate the model by comparing with discriminating observables not used in the calibration, finding excellent agreement.

    ↳ nucl-thhep-phnucl-exPRL(2024)·41 citations
21. 21*

    Formation of trapped vacuum bubbles during inflation, and consequences for PBH scenarios

    Albert Escrivà🇯🇵 · Vicente Atal🇨🇱 · Jaume Garriga🇪🇸

    A class of inflationary scenarios for primordial black hole (PBH) formation include a small barrier in the slope of the potential. There, the inflaton slows down, generating an enhancement of primordial perturbations. Moreover, the background solution overcomes the barrier at a very low speed, and large backward quantum fluctuations can prevent certain regions from overshooting the barrier. This leads to localized bubbles where the field remains trapped behind the barrier. In such models, therefore, we have two distinct channels for PBH production: the standard adiabatic density perturbation channel and the bubble channel. Here, we perform numerical simulations of bubble formation, addressing the issues of initial conditions, critical amplitude and bubble expansion. Further, we explore the scaling behaviour of the co-moving size of bubbles with the initial amplitude of the field fluctuation. We find that for small to moderate non-Gaussianity $f_{\mathrm{NL}}\lesssim 2.6$, the threshold for the formation of vacuum bubbles agrees with previous analytical estimates arXiv:1908.11357 to $5\%$ accuracy or so. We also show that the mass distribution for the two channels is different, leading to a slightly broader range of PBH masses. The bubble channel is subdominant for small $f_{\mathrm{NL}}$, and becomes dominant for $f_{\mathrm{NL}}\gtrsim 2.6$. We find that the mass of PBHs in the bubble channel is determined by an adiabatic overdensity surrounding the bubble at the end of inflation. Remarkably, the profile of this overdensity turns out to be of type-II. This represents a first clear example showing that overdensities of type-II can be dominant relative to the standard type-I. We also comment on exponential tails and on the fact that in models with local type non-Gaussianity (such as the one considered here), the occurrence of alternative channels can easily be inferred from unitarity considerations.

    ↳ astro-ph.COgr-qchep-phJCAP(2023)·43 citations
22. 22*

    Global features of fast neutrino-flavor conversion in binary neutron star merger

    Hiroki Nagakura🇯🇵

    Binary neutron star merger (BNSM) offers an environment where fast neutrino-flavor conversion (FFC) can vividly occur, that potentially leads to a considerable change of neutrino radiation field. In this Letter, we investigate global features of FFC by general relativistic quantum kinetic neutrino transport simulations in spatial axisymmetry. Our result suggests that global advection of neutrinos plays a crucial role in FFC dynamics. Although flavor conversions occur ubiquitously in the early phase, they can be active only in a narrow region in the late phase. This region includes an ELN-XLN Zero Surface (EXZS), corresponding to a surface where electron-neutrinos lepton number (ELN) equals to heavy-leptonic one (XLN). The EXZS is not stationary, but dynamically evolve in a time scale of global advection. We also find that neutrinos can undergo a flavor swap when they pass through the EXZS, resulting in qualitatively different neutrino radiation fields between both sides of EXZS. Our result suggests that EXZS is one of the key ingredients to characterize FFC in BNSM.

    ↳ astro-ph.HEgr-qchep-phPRD(2023)·38 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.