Fri·Sep 24, 2021Friday·September 24, 2021

1. 01*

   Effective Leptophilic WIMPs at the $e^{+}{e}^{-}$ collider

   Basabendu Barman🇨🇴 · Subhaditya Bhattacharya🇮🇳 · Sudhakantha Girmohanta🇺🇸 · Sahabub Jahedi🇮🇳

   We consider higher-dimensional effective (EFT) operators consisting of fermion dark matter (DM) connecting to Standard Model (SM) leptons upto dimension six. Considering all operators together and assuming the DM to undergo thermal freeze-out, we find out relic density allowed parameter space in terms of DM mass ($m_{\chi }$) and New Physics (NP) scale ($\Lambda$) with one loop direct search constraints from XENON1T experiment. Allowed parameter space of the model is probed at the proposed International Linear Collider (ILC) via monophoton signal for both Dirac and Majorana cases, limited by the centre-of-mass energy $\sqrt{s}=$1 TeV, where DM mass can be probed within $m_{\chi }<\frac{\sqrt{s}}{2}$ for the pair production to occur and $\Lambda >\sqrt{s}$ for the validity of EFT framework.

   hep-phhep-exJHEP(2022)·35 citations
2. 02*

   Multiple Hierarchies from a Warped Extra Dimension

   Seung J. Lee🇰🇷 · Yuichiro Nakai🇨🇳 · Motoo Suzuki🇨🇳

   Theories beyond the Standard Model often contain mass scales hierarchically different from the electroweak scale and the Planck scale. It has been shown that such hierarchical mass scales can be realized as typical energy scales of multiple 3-branes in a 5D warped spacetime. We present a mechanism for stabilizing the intervals between the multiple 3-branes in the warped extra dimension, by introducing a single 5D scalar field with brane-localized potentials. We discuss the radion stabilization by solving the Einstein equation and the scalar field equation of motion so that a backreaction effect on the geometry due to the presence of the scalar field is taken into account. Perturbations from the background configuration are then considered with proper identification of multiple radion degrees of freedom. By solving their equations of motion, we compute the mass spectrum of the radion-scalar field system and the radion couplings to brane-localized matter fields, which are found to be suppressed by typical energy scales and radion profiles at the branes. We also compute the mass spectrum of Kaluza-Klein gravitons and their profiles in the extra dimension. Some applications of the setup are briefly described. Our analysis provides a solid ground to build 5D warped extra dimension models with multiple 3-branes.

   hep-phhep-thJHEP(2022)·25 citations
3. 03*

   Searching for New Physics in Rare $K$ and $B$ Decays without $|V_{cb}|$ and $|V_{ub}|$ Uncertainties

   Andrzej J. Buras🇩🇪 · Elena Venturini🇩🇪

   We reemphasize the strong dependence of the branching ratios $B(K^{+}\to {\pi }^{+}\nu \bar{\nu })$ and $B(K_L\to {\pi }^0\nu \bar{\nu })$ on $|V_{cb}|$ that is stronger than in rare $B$ decays, in particular for $K_L\to {\pi }^0\nu \bar{\nu }$. Thereby the persistent tension between inclusive and exclusive determinations of $|V_{cb}|$ weakens the power of these theoretically clean decays in the search for new physics (NP). We demonstrate how this uncertainty can be practically removed by considering within the SM suitable ratios of the two branching ratios between each other and with other observables like the branching ratios for $K_S\to {\mu }^{+}{\mu }^{-}$, $B_{s,d}\to {\mu }^{+}{\mu }^{-}$ and $B\to K(K^{\ast })\nu \bar{\nu }$. We use as basic CKM parameters $V_{us}$, $|V_{cb}|$ and the angles $\beta$ and $\gamma$ in the unitarity triangle (UT). This avoids the use of the problematic $|V_{ub}|$. A ratio involving $B(K^{+}\to {\pi }^{+}\nu \bar{\nu })$ and $B(B_s\to {\mu }^{+}{\mu }^{-})$ while being $|V_{cb}|$-independent exhibits sizable dependence on the angle $\gamma$. It should be of interest for several experimental groups in the coming years. We point out that the $|V_{cb}|$-independent ratio of $B(B^{+}\to K^{+}\nu \bar{\nu })$ and $B(B_s\to {\mu }^{+}{\mu }^{-})$ from Belle II and LHCb signals a $1.8\sigma$ tension with its SM value. As a complementary test of the Standard Model, we propose to extract $|V_{cb}|$ from different observables as a function of $\beta$ and $\gamma$. We illustrate this with ${ϵ}_K$, $\Delta M_d$ and $\Delta M_s$ finding tensions between these three determinations of $|V_{cb}|$ within the SM. From $\Delta M_s$ and $S_{\psi K_S}$ alone we find $|V_{cb}|=41.8(6)\times 10^{-3}$ and $|V_{ub}|=3.65(12)\times 10^{-3}$. We stress the importance of a precise measurement of $\gamma$. We obtain most precise SM predictions for considered branching ratios of rare K and B decays to date.

   hep-phhep-exhep-latActa Phys.Polon.B·88 citations
4. 04*

   Two-loop application of the Breitenlohner-Maison/'t Hooft-Veltman scheme with non-anticommuting ${\gamma }_5$: Full renormalization and symmetry-restoring counterterms in an abelian chiral gauge theory

   Hermès Bélusca-Maïto🇭🇷 · Amon Ilakovac🇭🇷 · Paul Kühler🇩🇪 · Marija Ma{\dj}or-Božinović🇭🇷 · Dominik Stöckinger🇩🇪

   We apply the BMHV scheme for non-anticommuting ${\gamma }_5$ to an abelian chiral gauge theory at the two-loop level. As our main result, we determine the full structure of symmetry-restoring counterterms up to the two-loop level. These counterterms turn out to have the same structure as at the one-loop level and a simple interpretation in terms of restoration of well-known Ward identities. In addition, we show that the ultraviolet divergences cannot be canceled completely by counterterms generated by field and parameter renormalization, and we determine needed UV divergent evanescent counterterms. The paper establishes the two-loop methodology based on the quantum action principle and direct computations of Slavnov-Taylor identity breakings. The same method will be applicable to nonabelian gauge theories.

   hep-phhep-thJHEP(2021)·34 citations
5. 05*

   Effects of the quark anomalous magnetic moment in the chiral symmetry restoration: magnetic catalysis and inverse magnetic catalysis

   Ricardo L. S. Farias🇧🇷 · William R. Tavares🇧🇷 · Rodrigo M. Nunes🇺🇸 · Sidney S. Avancini🇧🇷

   In this work, we consider the effect of a constant anomalous magnetic moment (AMM) of quarks in the SU(2) Nambu--Jona-Lasinio model in the mean field approximation. To this end, we use the Schwinger {\it ansatz}, which represents a linear magnetic field term in the Lagrangian. A regularization method inspired in the vacuum magnetic regularization (VMR) is adopted to avoid ultraviolet divergences. Our results indicate a smooth decrease of the pseudocritical temperature and quark condensates for magnetic fields $B\le 0.1$ GeV${}^2$ when a sizable AMM is considered. We found only a small window for Inverse Magnetic Catalysis (IMC), in contradiction with NJL predictions made in the literature. For a low value of AMM, we observe for all ranges of magnetic fields considered that the pseudocritical temperature increases with the magnetic field, indicating only Magnetic Catalysis (MC). In our approach, for nonvanishing quark AMM, the chiral symmetry restoration happens always as a smooth crossover and never turns into a first order phase transition.

   hep-phhep-lathep-thnucl-thEPJC(2022)·33 citations
6. 06*

   Use of $Z$ polarization in $e^{+}{e}^{-}\to ZH$ to measure the triple-Higgs coupling

   Kumar Rao (1)🇮🇳 · Saurabh D. Rindani (2)🇮🇳 · Priyanka Sarmah (1)🇮🇳 · Balbeer Singh (3) ((1) IIT Bombay, (2) Phys. Res. Lab. Ahmedabad, (3) TIFR Mumbai)🇮🇳

   It is shown that a certain angular asymmetry of charged leptons produced in the decay of $Z$ in the process $e^{+}{e}^{-}\to ZH$, related to a tensor polarization component of the $Z$, can be used to constrain the anomalous triple-Higgs coupling, independent of the other anomalous couplings like the $ZZH$ coupling which dominate at tree level. This is because the angular asymmetry is odd under naïve time reversal, and hence dependent on loop-level contributions. At a future $e^{+}{e}^{-}$ collider like the International Linear Collider (ILC), for example, a limit of about $3.4$ might be placed on the ratio of the actual triple Higgs coupling to that predicted in the standard model for a centre-of-mass energy of 500 GeV and an integrated luminosity of 30 fb${}^{-1}$ with electron and positron beams having longitudinal polarization of $-80\%$ and $+30\%$, respectively.

   hep-phhep-exNPB(2022)·6 citations
7. 07*

   Dark-matter prolate halo shapes from fits to SPARC galaxy rotation curves

   Adriana Bariego Quintana🇪🇸 · Felipe J. Llanes-Estrada🇪🇸 · Oliver Manzanilla Carretero (Univ. Complutense de Madrid)🇪🇸

   The shape distortion of the presumed Milky Way dark matter halo can impact the local density of dark matter and thus the direct detection program. We examine the population of galactic rotation curves measured by SPARC and fit them to dark matter haloes that are distorted with a multipole density distribution, finding a significantly better fit with prolate haloes over spherically symmetric ones. This is to be expected since the long-distance Rubin flattening v(r)= constant is the natural Kepler law due to a filamentary rather than a spherical source. Then, elongating the distribution brings about a smaller squared chi, all other things being equal, including the use of several different radial dark matter profiles. The ellipticities that we fit to rotation curve data seem to be much more significant than those computed in cosmological simulations of dark matter haloes. If the Milky Way's halo would be typical of the spiral-galaxy SPARC sample (which we presently ignore), the local dark matter density might currently be overestimated by a factor 2. This would carry on into dark-matter cross-section bounds.

   hep-phPoS(2022)·2 citations
8. 08*

   Effects of an Intermediate Mass Sterile Neutrino Population on the Early Universe

   Hannah Rasmussen (1)🇺🇸 · Alex McNichol (1)🇺🇸 · George M. Fuller (2)🇺🇸 · Chad T. Kishimoto (1 and 2) ((1) Department of Physics and Biophysics, University of San Diego, (2) Center for Astrophysics and Space Sciences, University of California, San Diego)🇺🇸

   The hot and dense early Universe combined with the promise of high-precision cosmological observations provide an intriguing laboratory for Beyond Standard Model (BSM) physics. We simulate the early Universe to examine the effects of the decay of thermally populated sterile neutrino states into Standard Model products around the time of weak decoupling. These decays deposit a significant amount of entropy into the plasma as well as produce a population of high-energy out-of-equilibrium active neutrinos. As a result, we can constrain these models by their inferred value of $N_{\mathrm{eff}}$, the effective number of relativistic degrees of freedom. In this work, we explore a variety of models with $N_{\mathrm{eff}}$ values consistent with CMB observations, but with vastly different active neutrino spectra which will challenge the standard cosmological model, affect lepton capture rates on free nucleons, and may significantly affect Big Bang Nucleosynthesis (BBN).

   hep-phastro-ph.COPRD(2022)·18 citations
9. 09*

   Flipped SU(5) with modular $A_4$ symmetry

   Georgianna Charalampous🇬🇷 · Stephen F. King🇬🇧 · George K. Leontaris🇬🇷 · Ye-Ling Zhou🇨🇳

   We study Flipped $SU(5)\times U(1)$ Grand Unified Theories (GUTs) with ${\Gamma }_3\simeq A_4$ modular symmetry. We propose two models with different modular weights assignments, where the fermion mass hierarchy can arise from weighton fields. In order to relax the constraint on the Dirac neutrino Yukawa matrix we appeal to mechanisms which allow incomplete GUT representations, allowing a good fit to quark and charged lepton masses and quark mixing for a single modulus field $\tau$, with the neutrino masses and lepton mixing well determined by the type I seesaw mechanism, at the expense of some tuning. We also discuss the double seesaw possibility allowed by the extra singlets generically predicted in such string inspired theories.

   hep-phPRD(2021)·32 citations
10. 10*

    Unified FSM treatment of CP physics extended to hidden sector giving (i) ${\delta }_{CP}$ for leptons as prediction, (ii) new hints on the material content of the universe

    José Bordes (1)🇪🇸 · H.M. Chan (2)🇬🇧 · S.T. Tsou (3) ((1) Departament Fisica Teorica and IFIC, Universitat de Valencia, Spain, (2) Rutherford Appleton Laboratory, United Kingdom, (3) Mathematical Institute, University of Oxford, United Kingdom)🇬🇧

    A unified treatment of CP physics for quarks and leptons in the framed standard model (FSM) is extended to include the predicted hidden sector giving as consequences: (i) that an earlier part-estimate of the Jarlskog invariant $J^{\prime }$ for leptons is turned into a prediction for its actual value, i.e., $J^{\prime }\sim -0.012$ (${\delta }_{CP}^{\prime }\sim 1.11\pi$), which is of the right order of magnitude, of the right sign, and in the range of values favoured by present experiment, (ii) some novel twists to the effects of CP-violation on the material content of the universe.

    hep-phInt.J.Mod.Phys.A(2021)·5 citations
11. 11*

    Kinematic regions in the $e^{+}{e}^{-}\to hX$ factorized cross section in a $2$-jet topology with thrust

    M. Boglione🇮🇹 · A. Simonelli🇮🇹

    Factorization theorems allow to separate out the universal, non-perturbative content of the hadronic cross section from its perturbative part, which can be computed in perturbative QCD, up to the desired order. In this paper, we derive a rigorous proof of factorization of the $e^{+}{e}^{-}\to hX$ cross section, sensitive to the transverse momentum of the detected hadron with respect to the thrust axis, in a completely general framework, based on the Collins-Soper-Sterman approach. The results are explicitly computed to NLO-NLL accuracy and subsequently generalized to all orders in perturbation theory. This procedure naturally leads to a partition of the $e^{+}{e}^{-}\to hX$ kinematics into three different regions, each associated to a different factorization theorem. In one of these regions, which covers the central and widest range, the factorization theorem has a new structure, which shares the features of both TMD and collinear factorization schemes. In the corresponding cross section, the role of the rapidity cut-off is investigated, as its physical meaning becomes increasingly evident. An algorithm to identify these three kinematic regions, based on ratios of observable quantities, is provided.

    hep-phJHEP(2022)·15 citations
12. 12*

    Cancellation mechanism of dark matter direct detection in Higgs-portal and vector-portal models

    Chengfeng Cai🇨🇳 · Yu-Pan Zeng🇨🇳 · Hong-Hao Zhang🇨🇳

    We present two alternative proofs for the cancellation mechanism in the U(1) symmetric pseudo-Nambu-Goldstone-Boson Dark Matter (pNGB DM) model. They help us to have a better understanding of the mechanism from multi-angle, and inspire us to propose some interesting generalizations. In the first proof, we revisit the non-linear representation method and rephrase the argument with the interaction eigenstates. In this picture, the phase mode (DM) can only have a trilinear interaction with a derivative-squared acting on the radial mode when the DM is on-shell. Thus, the DM-quark scattering generated by a mass mixing between the radial mode and the Higgs boson vanishes in the limit of zero-momentum transfer. Using the same method, we can easily generalize the model to an SO(N) model with general soft-breaking structures. In particular, we study the soft-breaking cubic terms and identify those terms which preserve the cancellation mechanism for the DM candidate. In our discussion of the second method, we find that the cancellation relies on the special structure of mass terms and interactions of the mediators. This condition can be straightforwardly generalized to the vector-portal models. We provide two examples of the vector-portal case where the first one is an SU(2)_L \times U(1)_Y \times U(1)_X model and the second one is an SU(2)_L \times U(1)_Y \times U(1)_(B-L) \times U(1)_X model. In the first model, the vector mediators are the Z_nu boson and a new U(1)_X gauge boson X_nu, while in the second model the mediators are the U(1)_(B-L) and U(1)_X gauge bosons. The cancellation mechanism works in both models when there are no generic kinetic mixing terms for the gauge bosons. Once the generic kinetic mixing terms are included, the first model requires a fine-tuning of the mixing parameter to avoid the stringent direct detection bound, while the second model can naturally circumvent it.

    hep-phastro-ph.COhep-exJHEP(2022)·19 citations
13. 13*

    Dark Confinement and Chiral Phase Transitions: Gravitational Waves vs Matter Representations

    Manuel Reichert🇬🇧 · Francesco Sannino🇩🇰 · Zhi-Wei Wang🇩🇰 · Chen Zhang🇮🇹

    We study the gravitational-wave signal stemming from strongly coupled models featuring both, dark chiral and confinement phase transitions. We therefore identify strongly coupled theories that can feature a first-order phase transition. Employing the Polyakov-Nambu-Jona-Lasinio model, we focus our attention on SU(3) Yang-Mills theories featuring fermions in fundamental, adjoint, and two-index symmetric representations. We discover that for the gravitational-wave signals analysis, there are significant differences between the various representations. Interestingly we also observe that the two-index symmetric representation leads to the strongest first-order phase transition and therefore to a higher chance of being detected by the Big Bang Observer experiment. Our study of the confinement and chiral phase transitions is further applicable to extensions of the Standard Model featuring composite dynamics.

    hep-phastro-ph.HEgr-qchep-lat+1JHEP(2022)·71 citations
14. 14*

    A first order dark $SU(2{)}_D$ phase transition with vector dark matter in the light of NANOGrav 12.5 yr data

    Debasish Borah🇮🇳 · Arnab Dasgupta🇺🇸 · Sin Kyu Kang🇰🇷

    We study a dark $SU(2{)}_D$ gauge extension of the standard model (SM) with the possibility of a strong first order phase transition (FOPT) taking place below the electroweak scale in the light of NANOGrav 12.5 yr data. As pointed out recently by the NANOGrav collaboration, gravitational waves (GW) from such a FOPT with appropriate strength and nucleation temperature can explain their 12.5 yr data. We impose a classical conformal invariance on the scalar potential of $SU(2{)}_D$ sector involving only a complex scalar doublet with negligible couplings with the SM Higgs. While a FOPT at sub-GeV temperatures can give rise to stochastic GW around nano-Hz frequencies being in agreement with NANOGrav findings, the $SU(2{)}_D$ vector bosons which acquire masses as a result of the FOPT in dark sector, can also serve as dark matter (DM) in the universe. The relic abundance of such vector DM can be generated in a non-thermal manner from the SM bath via scalar portal mixing. We also discuss future sensitivity of gravitational wave experiments to the model parameter space.

    hep-phastro-ph.COJCAP(2021)·19 citations
15. 15*

    Probing a dilute short lived Quark Gluon Plasma medium with jets

    Varun Vaidya🇺🇸

    I look at propagation of jets that act as a probe of the medium in the phenomenologically relevant case of a short lived dilute Quark Gluon Plasma(QGP) created during heavy ion collisions. Working in the regime where the lifetime of the medium is of the order or smaller than the formation time of the energetic jet, I derive a factorization formula with a manifest separation of scales for an illustrative jet substructure observable using the Open Quantum system Effective Field Theory(EFT) approach developed in \cite{Vaidya:2020lih}, in terms of a medium structure function and a medium induced jet function . The medium structure function or the "PDF of the medium" that describes the observable independent physics of the QGP remains identical to that in a dilute long lived medium considered in \cite{Vaidya:2021vxu}, while the medium induced jet function is modified and incorporates quantum interference between the hard interaction that creates the jet and subsequent medium interactions. The medium jet function continues to enjoy a BFKL rapidity evolution just as for a long lived medium, albeit with a modified renormalization scale that now depends on the medium lifetime.

    hep-phnucl-th9 citations
16. 16*

    Non-perturbative BRST symmetry and the spectral structure of the ghost propagator

    Shirley Weishi Li🇺🇸 · Peter Lowdon🇩🇪 · Orlando Oliveira🇵🇹 · Paulo J. Silva🇵🇹

    In BRST-quantised Yang-Mills theory the existence of BRST symmetry imposes significant constraints on the analytic structure of the continuum theory. In particular, the presence of this symmetry in the non-perturbative regime implies that any on-shell state with vanishing norm must have an associated partner state with identical mass, but negative inner product. In this work we demonstrate that for quantum chromodynamics (QCD) this constraint gives rise to an interconnection between the ghost and gluon spectra, and in doing so provides a non-trivial test of whether BRST symmetry is realised non-perturbatively. By analysing infrared lattice data for the minimal Landau gauge ghost propagator in pure $\mathrm{SU}(3)$ Yang-Mills theory, and comparing this with previous results for the gluon propagator, we show that this interconnection is violated, and hence conclude that continuum and current lattice formulations of Yang-Mills theory in Landau gauge represent two distinct realisations of the theory.

    ↳ hep-thhep-lathep-phPLB(2021)·13 citations
17. 17*

    Swampland Constraints on Neutrino Masses

    E. Gonzalo🇪🇸 · L.E. Ibáñez🇪🇸 · I. Valenzuela🇺🇸

    Compactifying the Standard Model (SM) on a circle may lead to AdS 3D vacua, depending on the character (Majorana or Dirac) and the mass of the lightest neutrino. It has been shown that, imposing the Ooguri-Vafa conjecture that no stable non-SUSY AdS vacua are consistent with Quantum Gravity, one can obtain conditions on the mass of the lightest neutrino. This result has the shortcoming that it is in general sensitive to the UV structure of the theory. In the present paper we show that two other independent swampland conditions may yield constraints very similar to those. These other two conditions come from the AdS swampland distance conjecture and the dS conjecture as applied to AdS vacua by Lust, Palti and Vafa. Unlike the non-SUSY AdS constraints, for these conjectures the results require only local IR information of the radion potential. We consider both the case of an explicit cosmological 4D constant and the alternative of a simple quintessence 4D potential. Cosmological data in the next decade may falsify the results, giving us information on the constraints of particle physics from Quantum Gravity.

    ↳ hep-thhep-phJHEP(2022)·47 citations
18. 18*

    Refined ultralight scalar dark matter searches with compact atom gradiometers

    Leonardo Badurina🇬🇧 · Diego Blas🇬🇧 · Christopher McCabe🇬🇧

    Atom interferometry is a powerful experimental technique that can be employed to search for the oscillation of atomic transition energies induced by ultralight scalar dark matter (ULDM). Previous studies have focused on the sensitivity to ULDM of km-length atom gradiometers, where atom interferometers are located at the ends of very long baselines. In this work, we generalize the treatment of the time-dependent signal induced by a linearly-coupled scalar ULDM candidate for vertical atom gradiometers of any length and find correction factors that especially impact the ULDM signal in short-baseline gradiometer configurations. Using these results, we refine the sensitivity estimates in the limit where shot noise dominates for AION-10, a compact 10 m gradiometer that will be operated in Oxford, and discuss optimal experimental parameters that enhance the reach of searches for linearly-coupled scalar ULDM. After comparing the reach of devices operating in broadband and resonant modes, we show that well-designed compact atom gradiometers are able to explore regions of dark matter parameter space that are not yet constrained.

    ↳ astro-ph.COhep-exhep-phphysics.atom-phPRD(2022)·49 citations
19. 19*

    Charmonium in nuclear matter and nuclei

    J.J. Cobos Martínez🇲🇽 · K. Tsushima🇧🇷 · G. Krein🇧🇷 · A.W. Thomas🇦🇺

    We present results for the ${\eta }_c$-nucleus bound state energies for various nuclei using an effective Lagrangians approach. The attractive potentials for the ${\eta }_c$ in the nuclear medium originate from the medium-modified intermediate $D{D}^{\ast }$ state in the ${\eta }_c$ self energy, using the local density approximation. Our results suggest that the ${\eta }_c$ should form bound states with all the nuclei considered

    ↳ nucl-thhep-exhep-phnucl-exPoS(2021)·1 citation
20. 20*

    Considerations on anomalous photon and Z-boson self-couplings from the Born-Infeld weak hypercharge action

    M. J. Neves🇧🇷 · L. P. R. Ospedal🇧🇷 · J. A. Helayël-Neto🇧🇷 · Patricio Gaete🇨🇱

    We investigate the effects of the Born-Infeld action on the Abelian sector of the electroweak model. The consequence of this approach is the emergence of anomalous couplings in the neutral sector of the $Z$-gauge boson and photon. These new couplings consist of quartic interactions of the photon with the $Z$-particle, as for example, three-photon-and-one-$Z$ vertex. With that, we obtain the decay width of $Z\to 3\gamma$ from which we impose a bound on the Born-Infeld parameter. Other bounds are also obtained from the photon quartic couplings. Subsequently, we consider the presence of an external uniform magnetic field in connection with this Born-Infeld weak hypercharge model. The magnetic background field yields new kinematic effects, like the kinetic mixing between the photon and the $Z$-boson, and we obtain thereby the corresponding dispersion relations for the mixed photon-$Z$-particle system. Finally, we calculate the lowest-order modifications to the interaction energy for the anomalous coupling $3\gamma -Z$, within the framework of the gauge-invariant but path-dependent variables formalism. Our results show that the interaction energy contains a linear term leading to the confinement of static probe charges. With the help of the potential that comes out, interparticle forces are estimated.

    ↳ hep-thhep-phEPJC(2022)·17 citations
21. 21*

    Callan-Rubakov Effect and Higher Charge Monopoles

    T. Daniel Brennan🇺🇸

    In this paper we study the interaction between magnetic monopoles and massless fermions. In the low energy limit, the monopole's magnetic field polarizes the fermions into purely in-going and out-going modes. Unitarity requires that the UV fermion-monopole interaction leads to non-trivial IR boundary conditions that relate the in-going to out-going modes. These non-trivial boundary conditions lead to what is known as the Callan-Rubakov effect. Here we derive the effective boundary condition by explicitly integrating out the UV degrees of freedom for the general class of spherically symmetric $SU(N)$ monopoles coupled to massless fermions of arbitrary representation. We then show that the boundary conditions preserve continuous symmetries without ABJ-type anomalies. As an application we explicitly derive the boundary conditions for the stable, spherically symmetric monopoles associated to the $SU(5)$ Georgi-Glashow model and comment on the relation to baryon number violation.

    ↳ hep-thhep-phJHEP(2023)·27 citations
22. 22*

    Angular analysis of $B^{+}\to {\rho }^{+}{\rho }^0$ decays reconstructed in 2019-2020 Belle II data

    Belle II collaboration: F. Abudinén🇮🇹 · I. Adachi🇯🇵 · R. Adak🇨🇳 · K. Adamczyk🇵🇱 · P. Ahlburg🇩🇪 · J. K. Ahn🇰🇷 · H. Aihara🇯🇵 · N. Akopov🇦🇲 · A. Aloisio🇮🇹 · F. Ameli🇮🇹 · L. Andricek🇩🇪 · N. Anh Ky🇻🇳 and 539 other authors

    We report on the first Belle II measurement of the branching fraction ($\mathcal{B}$) and longitudinal polarization fraction ($f_L$) of $B^{+}\to {\rho }^{+}{\rho }^0$ decays. We reconstruct $B^{+}\to {\rho }^{+}(\to {\pi }^{+}{\pi }^0(\to \gamma \gamma )){\rho }^0(\to {\pi }^{+}{\pi }^{-})$ decays in a sample of SuperKEKB electron-positron collisions collected by the Belle II experiment in 2019 and 2020 at the ${\rm Y}$(4S) resonance and corresponding to $62.8$ fb${}^{-1}$ of integrated luminosity. We fit the distributions of the difference between expected and observed $B$ candidate energy, continuum-suppression variable, dipion masses, and angular distributions of the resulting samples, to determine a signal yield of $104\pm 16$ events. The signal yields are corrected for efficiencies determined from simulation and control data samples to obtain $\mathcal{B}(B^{+}\to {\rho }^{+}{\rho }^0)=[20.6\pm 3.2(\mathrm{stat})\pm 4.0(\mathrm{syst})]\times 10^{-6}$, and $f_L(B^{+}\to {\rho }^{+}{\rho }^0)=0.936_{-0.041}^{+0.049}(\mathrm{stat})\pm 0.021(\mathrm{syst})$. This first Belle II $B^{+}\to {\rho }^{+}{\rho }^0$ angular analysis yields results compatible with previous determinations, and indicates Belle II performance superior to early Belle results.

    ↳ hep-exhep-ph2 citations
23. 23*

    Relaxation times for Bose-Einstein condensation by self-interaction and gravity

    Jiajun Chen🇩🇪 · Xiaolong Du🇺🇸 · Erik Lentz🇩🇪 · David J. E. Marsh🇬🇧

    In this paper, we study the Bose-Einstein condensation of a scalar field with an attractive self-interaction, with or without gravitational interactions. We confirm through full dynamical simulation that the condensation timescale due to self-interaction is inversely proportional to the square of the number density $n$ and the self-coupling constant $g$ : $\tau \propto n^{-2}{g}^{-2}$. We also investigate the condensation timescale when self-interaction and gravity are both important by solving the Gross-Pitaevskii-Poisson equations, and find that the condensation time scales according to an additive model for the cross section. We discuss the relevance of our results to theoretical models of boson star formation by condensation.

    ↳ astro-ph.COhep-phPRD(2022)·44 citations
24. 24*

    Natural Chain Inflation

    Katherine Freese🇺🇸 · Aliki Litsa🇸🇪 · Martin Wolfgang Winkler🇸🇪

    In Chain Inflation the universe tunnels along a series of false vacua of ever-decreasing energy. The main goal of this paper is to embed Chain Inflation in high energy fundamental physics. We begin by illustrating a simple effective formalism for calculating Cosmic Microwave Background (CMB) observables in Chain Inflation. Density perturbations seeding the anisotropies emerge from the probabilistic nature of tunneling (rather than from quantum fluctuations of the inflation). To obtain the correct normalization of the scalar power spectrum and the scalar spectral index, we find an upper limit on the scale of inflation at horizon crossing of CMB scales, $V_{\ast }^{1/4}<10^{12}$~GeV. We then provide an explicit realization of chain inflation, in which the inflaton is identified with an axion in supergravity. The axion enjoys a perturbative shift symmetry which is broken to a discrete remnant by instantons. The model, which we dub `natural chain inflation' satisfies all cosmological constraints and can be embedded into a standard $\Lambda$CDM cosmology. Our work provides a major step towards the ultraviolet completion of chain inflation in string theory.

    ↳ hep-thastro-ph.COhep-phPLB(2022)·8 citations
25. 25*

    On the Accuracy of Underground Muon Intensity Calculations

    Anatoli Fedynitch🇯🇵 · William Woodley🇨🇦 · Marie-Cecile Piro🇨🇦

    Cosmic ray muons detected by deep underground and underwater detectors have served as an information source on the high-energy cosmic ray spectrum and hadronic interactions in air showers for almost a century. The theoretical interest in underground muons has nearly faded because space-borne experiments probe the cosmic ray spectrum more directly, and accelerators provide precise measurements of hadron yields. However, underground muons probe unique hadron interaction energies and phase space, which are still inaccessible to present accelerator experiments. The cosmic ray nucleon energies reach the hundred-TeV and PeV ranges, which are barely accessible with space-borne experiments. Our new calculation combines two modern computational tools: MCEq, for surface muon fluxes, and PROPOSAL, for underground transport. We demonstrate excellent agreement with measurements of cosmic ray muon intensities underground within estimated errors. Beyond that, the precision of historical data turns out to be significantly smaller than our error estimates. This result shows that the sources of high-energy atmospheric lepton flux uncertainties at the surface or underground can be significantly constrained without taking more data or building new detectors. The reduction of uncertainties can be expected to impact data analyses at large-volume neutrino telescopes and for the design of future ton-scale direct dark matter detectors.

    ↳ astro-ph.HEhep-phApJ(2022)·30 citations

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