Fri·Mar 26, 2021Friday·March 26, 2021

1. 01*

   Evolution of Neutrino Mass-Mixing Parameters in Matter with Non-Standard Interactions

   Sanjib Kumar Agarwalla🇮🇳 · Sudipta Das🇮🇳 · Mehedi Masud🇰🇷 · Pragyanprasu Swain🇮🇳

   We explore the role of matter effect in the evolution of neutrino oscillation parameters in the presence of lepton-flavor-conserving and lepton-flavor-violating neutral-current non-standard interactions (NSI) of the neutrino. We derive simple approximate analytical expressions showing the evolution/running of mass-mixing parameters in matter with energy in the presence of standard interactions (SI) and SI+NSI (considering both positive and negative values of real NSI parameters). We observe that only the NSI parameters in the (2,3) block, namely ${\epsilon }_{\mu \tau }$ and $(\gamma -\beta )\equiv ({\epsilon }_{\tau \tau }-{\epsilon }_{\mu \mu })$ affect the running of ${\theta }_{23}$. Though all the NSI parameters influence the evolution of ${\theta }_{13}$, ${\epsilon }_{e\mu }$ and ${\epsilon }_{e\tau }$ show a stronger impact at the energies relevant for DUNE. ${\theta }_{12}$ quickly approaches to $\sim$ $90^{\circ }$ with increasing energy in both SI and SI+NSI cases. The change in $\Delta m_{21,m}^2$ is quite significant as compared to $\Delta m_{31,m}^2$ both in SI and SI+NSI frameworks. Flipping the signs of the NSI parameters alters the way in which mass-mixing parameters run with energy. We demonstrate the utility of our approach in addressing several important features related to neutrino oscillation such as: a) unraveling interesting degeneracies between ${\theta }_{23}$ and NSI parameters, b) estimating the resonance energy in presence of NSI when ${\theta }_{13}$ in matter becomes maximal, c) figuring out the required baselines and energies to have maximal matter effect in ${\nu }_{\mu }$ $\to$ ${\nu }_e$ transition in the presence of different NSI parameters, and d) studying the impact of NSI parameters ${\epsilon }_{\mu \tau }$ and $(\gamma -\beta )$ on the ${\nu }_{\mu }\to {\nu }_{\mu }$ survival probability.

   hep-phhep-exJHEP(2021)·25 citations
2. 02*

   Collisional strong-field QED kinetic equations from first principles

   Gregor Fauth🇩🇪 · Jürgen Berges🇩🇪 · Antonino Di Piazza🇩🇪

   Starting from nonequilibrium quantum field theory on a closed time path, we derive kinetic equations for the strong-field regime of quantum electrodynamics (QED) using a systematic expansion in the gauge coupling $e$. The strong field regime is characterized by a large photon field of order $\mathcal{O}(1/e)$, which is relevant for the description of, e.g., intense laser fields, the initial stages of off-central heavy ion collisions, and condensed matter systems with net fermion number. The strong field enters the dynamical equations via both quantum Vlasov and collision terms, which we derive to order $\mathcal{O}(e^2)$. The kinetic equations feature generalized scattering amplitudes that have their own equation of motion in terms of the fermion spectral function. The description includes single photon emission, electron-positron pair photoproduction, vacuum (Schwinger) pair production, their inverse processes, medium effects and contributions from the field, which are not restricted to the so-called locally-constant crossed field approximation. This extends known kinetic equations commonly used in strong-field QED of intense laser fields. In particular, we derive an expression for the asymptotic fermion pair number that includes leading-order collisions and remains valid for strongly inhomogeneous fields. For the purpose of analytically highlighting limiting cases, we also consider plane-wave fields for which it is shown how to recover Furry-picture scattering amplitudes by further assuming negligible occupations. Known on-shell descriptions are recovered in the case of simply peaked ultrarelativistic fermion occupations. Collisional strong-field equations are necessary to describe the dynamics to thermal equilibrium starting from strong-field initial conditions.

   hep-phhep-thPRD(2021)·25 citations
3. 03*

   Exotic diboson $Z^{\prime }$ decays in the U$\mu \nu$SSM

   J.A. Aguilar-Saavedra🇪🇸 · I. Lara🇵🇱 · D.E. López-Fogliani🇦🇷 · C. Muñoz🇪🇸

   Searches for new leptophobic resonances at high energy colliders usually target their decay modes into pairs of light quarks, top quarks, or standard model bosons. Additional decay modes may also be present, producing signatures to which current searches are not sensitive. We investigate the performance of generic searches that look for resonances decaying into two large-radius jets. As benchmark for our analysis we use a supersymmetric $\text{U}(1{)}^{\prime }$ extension of the Standard Model, the so-called U$\mu \nu$SSM, where all the SM decay modes of the $Z^{\prime }$ boson take place, plus additional (cascade) decays into new scalars. The generic searches use a generic multi-pronged jet tagger and take advantage of the presence of $b$ quarks in the large-radius jets, and are sensitive to all these $Z^{\prime }$ decay modes (except into light quarks) at once. For couplings that are well below current experimental constraints, these generic searches are sensitive at the $3\sigma -4\sigma$ level with Run 2 LHC data.

   hep-phhep-exEPJC(2021)·5 citations
4. 04*

   Nucleon matrix element of Weinberg's CP-odd gluon operator from the instanton vacuum

   C. Weiss🇺🇸

   We calculate the nucleon matrix element of Weinberg's dimension-6 CP-odd gluon operator $f^{abc}({\tilde{F}}_{\mu \nu }{)}^a(F^{\mu \rho }{)}^b(F_{\rho }^{\nu }{)}^c$ in the instanton vacuum. In leading order of the instanton packing fraction, the dimension-6 operator is effectively proportional to the topological charge density $({\tilde{F}}_{\mu \nu }{)}^a(F^{\mu \nu }{)}^a$, whose nucleon matrix element is given by the flavor-singlet axial charge and constrained by the $U(1{)}_A$ anomaly. The nucleon matrix element of the dimension-6 operator is obtained substantially larger than in other estimates, because of the strong localization of the nonperturbative gluon fields in the instanton vacuum. We argue that the neutron electric dipole moment induced by the dimension-6 operator is nevertheless of conventional size.

   hep-phPLB(2021)·13 citations
5. 05*

   Enlighting the transverse structure of the proton via double parton scattering in photon-induced interactions

   Matteo Rinaldi🇮🇹 · Federico Alberto Ceccopieri🇫🇷

   In the present paper we address double parton scattering (DPS) in quasi-real photon-proton interactions. By using electromagnetic and hadronic models of the photon light cone wave functions, we compute the so-called effective cross-section, ${\sigma }_{eff}^{\gamma p}$ which allows us to calculate the DPS contribution to these processes under dedicated assumptions. In particular, for the four-jet photoproduction in HERA kinematics we found a sizeable DPS contribution. We show that if the photon virtuality $Q^2$ could be measured and thus the dependence of ${\sigma }_{eff}^{\gamma p}$ on such a parameter exposed, information on the transverse distance between partons active in proton could be extracted. To this aim, we set lower limits on the integrated luminosity needed to observe such an effect which would allow the extraction of novel information on the proton structure.

   hep-phnucl-thPRD(2022)·10 citations
6. 06*

   Quark-Gluon Plasma and Nucleons a la Laughlin

   Wei Lu🇺🇸

   Inspired by Laughlin's theory of the fractional quantum Hall effect, we explore the topological nature of the quark-gluon plasma and the nucleons in the context of the Clifford algebra. In our model, each quark is transformed into a composite particle via the simultaneous attachment of a spin monopole and an isospin monopole. This is induced by a novel kind of meson endowed with both spin and isospin degrees of freedom. The interactions in the strongly coupled quark-gluon system are governed by the topological winding number of the monopoles, which is an odd integer to ensure that the overall wave function is antisymmetric. The states of the quark-gluon plasma and the nucleons are thus uniquely determined by the combination of the monopole winding number m and the total quark number N. The radius squared of the quark-gluon plasma droplet is expected to be proportional to mN. We anticipate the observation of such proportionality in the heavy ion collision experiments.

   hep-phcond-mat.mes-hallhep-thnucl-thInt.J.Geom.Meth.Mod.Phys.(2022)·1 citation
7. 07*

   Peccei-Quinn Symmetry Breaking via Asymptotically Safe Dynamical Scalegenesis: A Walking Axicolor and Axion

   Hiroyuki Ishida🇯🇵 · Shinya Matsuzaki🇨🇳 · Xiao-Chang Peng🇨🇳

   Pecci-Quinn (PQ) symmetry breaking by perturbative dynamics would suffer from a hierarchy problem, just like the electroweak symmetry breaking in the standard model. The dynamics of the axion, associated with the PQ symmetry breaking, would also involve a triviality problem. We provide a paradigm to resolve those two problems potentially existing in the PQ symmetry breaking scenario, with keeping successful axion relaxation for the QCD strong CP phase. The proposed theory includes an axicolor dynamics with the axicolored fermions partially gauged by the QCD color, and is shown to be governed by an asymptotically safe (AS) fixed point: quantum scale invariance is built. The AS axicolor is actually a ``walking" dynamics, which dynamically breaks a PQ symmetry, a part of the chiral symmetry carried by the axicolored fermions. The PQ scale generation is then triggered by the nonperturbative dimensional transmutation in the ``walking" dynamics. A composite axion emerges as the assosiated Nambu-Goldstone boson. That is, no hierarchy or triviality problem is present there. The composite axion can potentially be light due to the characteristic feature of the AS axicolor (``walking" axicolor), becomes the QCD axion in the anti-Veneziano limit, and gets heavier by the subleading correction. The composite axion relaxes the QCD theta parameter, involving heavier relaxation partners such as axicolored pseudoscalar mesons, and the ultraviolet correction to the relaxation mechanism is protected by the established (near) scale invariance during the ``walking" regime.

   hep-phhep-thEPJC(2022)·8 citations
8. 08*

   Decay of the Higgs boson $h\to {\tau }^{-}{\tau }^{+}\to {\pi }^{-}{\nu }_{\tau }{\pi }^{+}{\bar{\nu }}_{\tau }$ for a non-Hermitian Yukawa interaction

   A.Yu. Korchin🇺🇦 · V.A. Kovalchuk🇺🇦

   The differential rate of the decay of the Higgs boson ($h$) to a pair of $\tau$ leptons with their subsequent decay in the ${\tau }^{-}\to {\pi }^{-}{\nu }_{\tau }$ and ${\tau }^{+}\to {\pi }^{+}{\bar{\nu }}_{\tau }$ channels is studied. The Yukawa interaction between the Higgs boson and the $\tau$ leptons is assumed to include scalar ($S$) and pseudoscalar ($PS$) couplings. Angular distributions of the pions in the $h\to {\tau }^{-}{\tau }^{+}\to {\pi }^{-}{\nu }_{\tau }{\pi }^{+}{\bar{\nu }}_{\tau }$ decay are considered. For real values of the $S$ and $PS$ couplings, this decay is known to be a source of information on $\mathcal{C}\mathcal{P}$ violation in the $h\tau \tau$ interaction. In the present paper, the main attention is paid to a possible non-Hermiticity of this interaction. Influence of non-Hermiticity on the distribution of the angle between planes of the ${\tau }^{-}\to {\pi }^{-}{\nu }_{\tau }$ and ${\tau }^{+}\to {\pi }^{+}{\bar{\nu }}_{\tau }$ decays, and distribution of the polar angle of one of the pions are analyzed. Asymmetries sensitive to parameters of $\mathcal{C}\mathcal{P}$ violation and non-Hermiticity of $h\tau \tau$ interaction are proposed.

   hep-phActa Phys.Polon.B(2022)·4 citations
9. 09*

   Improved determination of strange distribution function from the global analysis using BHPS model

   Maral Salajegheh🇮🇷 · S. Mohammad Moosavi Nejad🇮🇷 · S. Atashbar Tehrani🇮🇷

   We study the impact of intrinsic strange (IS) component of nucleon sea on the global analysis of parton distribution functions (PDFs) considering a wide range of experimental data. To this aim, we consider two scenarios on the basis of BHPS model results for the IS distribution. In the first scenario, we apply the results presented through the BHPS model and in the second scenario we use its evolved distributions. For each scenarios, we present the limit of the IS probability ${\mathcal{P}}_5^{s\bar{s}}$ for the standard tolerance criteria $\Delta {\chi }^2=1$ and $18.112$ at $1\sigma$ and $4\sigma$ levels. Our results show that the experimental data can tolerate an IS component with a greater probability ${\mathcal{P}}_5^{s\bar{s}}$ if one employs the second scenario. We obtain ${\mathcal{P}}_5^{s\bar{s}}\approx 0.01$ and ${\mathcal{P}}_5^{s\bar{s}}\approx 0.025$ for $\Delta {\chi }^2=1$ and $18.112$, respectively, at the $4\sigma$ level. We also calculate the ratio of strange-to-light sea-quark densities $r_s$ in the proton both including and excluding the IS component. Our results show that one can obtain a higher value for the ratio $r_s$ if the IS component is included.

   hep-phFew Body Syst.(2021)·0 citations
10. 10*

    A unified formalism to study $soft$ as well as $hard$ part of the transverse momentum spectra

    Rohit Gupta🇮🇳 · Satyajit Jena🇮🇳

    Transverse momentum $p_T$ spectra of final state particles produced in high energy heavy-ion collision can be divided into two distinct regions based on the difference in the underlying particle production process. We have provided a unified formalism to explain both low- and high-$p_T$ regime of spectra in a consistent manner. The $p_T$ spectra of final state particles produced at RHIC and LHC energies have been analysed using unified formalism to test its applicability at different energies, and a good agreement with the data is obtained across all energies. Further, the prospect of extracting the elliptic flow coefficient directly from the transverse momentum spectra is explored.

    hep-phSpringer Proc.Phys.(2022)·1 citation
11. 11*

    Light-cone sum rules for proton decay

    Ulrich Haisch🇩🇪 · Amando Hala🇩🇪

    We estimate the form factors that parametrise the hadronic matrix elements of proton-to-pion transitions with the help of light-cone sum rules. These form factors are relevant for semi-leptonic proton decay channels induced by baryon-number violating dimension-six operators, as typically studied in the context of grand unified theories. We calculate the form factors in a kinematical regime where the momentum transfer from the proton to the pion is space-like and extrapolate our final results to the regime that is relevant for proton decay. In this way, we obtain estimates for the form factors that show agreement with the state-of-the-art calculations in lattice QCD, if systematic uncertainties are taken into account. Our work is a first step towards calculating more involved proton decay channels where lattice QCD results are not available at present.

    hep-phJHEP(2021)·10 citations
12. 12*

    A Model of Muon Anomalies

    Admir Greljo🇨🇭 · Peter Stangl🇨🇭 · Anders Eller Thomsen🇨🇭

    The Standard Model (SM) is augmented with a $\mathrm{U}(1{)}_{B-3L_{\mu }}$ gauge symmetry spontaneously broken above the TeV scale when an SM-singlet scalar condenses. Scalar leptoquarks $S_{1(3)}=(\overline{3},1(3),{}^1{/}_3)$ charged under $\mathrm{U}(1{)}_{B-3L_{\mu }}$ mediate the intriguing effects observed in muon $(g-2)$, $R_{K^{(\ast )}}$ and $b\to s{\mu }^{+}{\mu }^{-}$, while generically evading all other phenomenological constraints. The fermionic sector is minimally extended with three right-handed neutrinos, and a successful type-I seesaw mechanism is realized. Charged lepton flavor violation is effectively suppressed, and proton decay - a common prediction of leptoquarks - is postponed to the dimension-6 effective Lagrangian. Unavoidable radiative corrections in the Higgs mass and muon Yukawa favor leptoquark masses interesting for collider searches. The parameters of the model are radiatively stable and can be evolved by the renormalization group to the Planck scale without inconsistencies. Alternative lepton-flavored gauge extensions of the SM, under which leptoquarks become muoquarks, are proposed for comparison.

    hep-phPLB(2021)·92 citations
13. 13*

    Cosmology of complex scalar dark matter: interplay of self-scattering and annihilation

    Avirup Ghosh🇮🇳 · Deep Ghosh🇮🇳 · Satyanarayan Mukhopadhyay🇮🇳

    The cosmology of a standard model (SM) gauge singlet complex scalar dark matter (DM), stabilized by a reflection symmetry, is studied including all renormalizable interactions that preserve the reflection symmetry but can break the larger global U(1) symmetry of DM number. We find an interesting interplay of the ensuing DM self-scatterings and annihilations in generating the present DM density, and possible particle-antiparticle asymmetry in the DM sector. The role of DM self-scatterings in determining its present density and composition is a novel phenomenon. The simultaneous presence of the self-scatterings and annihilations is required to obtain a non-zero asymmetry, which otherwise vanishes due to unitarity sum rules.

    hep-phastro-ph.COPRD(2021)·14 citations
14. 14*

    A new perspective on the electroweak phase transition in the Standard Model Effective Field Theory

    José Eliel Camargo-Molina🇸🇪 · Rikard Enberg🇸🇪 · Johan Löfgren🇸🇪

    A first-order Electroweak Phase Transition (EWPT) could explain the observed baryon-antibaryon asymmetry and its dynamics could yield a detectable gravitational wave signature, while the underlying physics would be within the reach of colliders. The Standard Model, however, predicts a crossover transition. We therefore study the EWPT in the Standard Model Effective Field Theory (SMEFT) including dimension-six operators. A first-order EWPT has previously been shown to be possible in the SMEFT. Phenomenology studies have focused on scenarios with a tree-level barrier between minima, which requires a negative Higgs quartic coupling and a new physics scale low enough to raise questions about the validity of the EFT approach. In this work we stress that a first-order EWPT is also possible when the barrier between minima is generated radiatively, the quartic coupling is positive, the scale of new physics is higher, and there is good agreement with experimental bounds. Our calculation is done in a consistent, gauge-invariant way, and we carefully analyze the scaling of parameters necessary to generate a barrier in the potential. We perform a global fit in the relevant parameter space and explicitly find the points with a first-order transition that agree with experimental data. We also briefly discuss the prospects for probing the allowed parameter space using di-Higgs production in colliders.

    hep-phastro-ph.COJHEP(2021)·44 citations
15. 15*

    The Muon Smasher's Guide

    Hind Al Ali🇺🇸 · Nima Arkani-Hamed🇺🇸 · Ian Banta🇺🇸 · Sean Benevedes🇺🇸 · Dario Buttazzo🇮🇹 · Tianji Cai🇺🇸 · Junyi Cheng🇺🇸 · Timothy Cohen🇺🇸 · Nathaniel Craig🇺🇸 · Majid Ekhterachian🇺🇸 · JiJi Fan🇺🇸 · Matthew Forslund🇺🇸 and 22 other authors

    We lay out a comprehensive physics case for a future high-energy muon collider, exploring a range of collision energies (from 1 to 100 TeV) and luminosities. We highlight the advantages of such a collider over proposed alternatives. We show how one can leverage both the point-like nature of the muons themselves as well as the cloud of electroweak radiation that surrounds the beam to blur the dichotomy between energy and precision in the search for new physics. The physics case is buttressed by a range of studies with applications to electroweak symmetry breaking, dark matter, and the naturalness of the weak scale. Furthermore, we make sharp connections with complementary experiments that are probing new physics effects using electric dipole moments, flavor violation, and gravitational waves. An extensive appendix provides cross section predictions as a function of the center-of-mass energy for many canonical simplified models.

    hep-phhep-exRept.Prog.Phys.(2022)·263 citations
16. 16*

    Uncovering a Spinor-Vector Duality on a Resolved Orbifold

    A.E. Faraggi🇬🇧 · S. Groot Nibbelink · M. Hurtado-Heredia🇬🇧

    Spinor-vector dualities have been established in various exact string realisations like orbifold and free fermionic constructions. This paper aims to investigate possibility of having spinor-vector dualities on smooth geometries in the context of the heterotic string. As a concrete working example the resolution of the T4/Z2 orbifold is considered with an additional circle supporting a Wilson line, for which it is known that the underlying orbifold theory exhibits such a duality by switching on/off a generalised discrete torsion phase between the orbifold twist and the Wilson line. Depending on this phase complementary parts of the twisted sector orbifold states are projected out, so that different blowup modes are available to generate the resolutions. As a consequence, not only the spectra of the dual pairs are different, but also the gauge groups are not identical making this duality less apparent on the blowup and thus presumably on smooth geometries in general.

    ↳ hep-thhep-phNPB(2021)·10 citations
17. 17*

    Missing final state puzzle in the monopole-fermion scattering

    Ryuichiro Kitano🇯🇵 · Ryutaro Matsudo🇯🇵

    It has been known that when a charged fermion scatters off a monopole, the fermion in the $s$-wave component must flip its chirality, i.e., fermion number violation must happen. This fact has led to a puzzle; if there are two or more flavors of massless fermions, any superposition of the fermion states cannot be the final state of the $s$-wave scattering as it is forbidden by conservation of the electric and flavor charges. The unitary evolution of the state vector, on the other hand, requires some interpretation of the final states. We solve the puzzle by finding new particle excitations in the monopole background, where multi-fermion operators exhibit condensation. The particles are described as excitations of closed-string configurations of the condensates.

    ↳ hep-thhep-phPLB(2022)·23 citations
18. 18*

    Recent theoretical developments on QCD matter at finite temperature and density

    Sayantan Sharma🇮🇳

    QCD matter at finite temperature and density is a subject that has witnessed very impressive theoretical developments in the recent years. In this review I will discuss some new insights on the microscopic degrees of freedom of the QCD medium near the chiral crossover transition from lattice QCD. Latest high precision lattice data on the fluctuations and correlations between conserved charges like the baryon number, strangeness can help us to understand and distinguish between different models of interacting hadrons. Furthermore, the latest constraints on the location of the critical end-point and the curvature of the critical line will be discussed. In the later part of this review I will discuss about the insights on the thermal nature of the medium created in heavy ion collision experiments that have come from the theoretical analysis of the particle yields, and to what extent the lattice data on correlations and fluctuations of conserved charges can give us any information about the fireball at freezeout.

    ↳ hep-lathep-phnucl-thIJMPE(2021)·4 citations
19. 19*

    Angular correlation as a novel probe of supermassive primordial black holes

    Takumi Shinohara🇯🇵 · Teruaki Suyama🇯🇵 · Tomo Takahashi🇯🇵

    We investigate the clustering property of primordial black holes (PBHs) in a scenario where PBHs can explain the existence of supermassive black holes (SMBHs) at high redshifts. We analyze the angular correlation function of PBHs originating from fluctuations of a spectator field which can be regarded as a representative model to explain SMBHs without conflicting with the constraint from the spectral distortion of cosmic microwave background. We argue that the clustering property of PBHs can give a critical test for models with PBHs as the origin of SMBHs and indeed show that the spatial distribution of PBHs in such a scenario is highly clustered, which suggests that those models may be disfavored from observations of SMBHs although a careful comparison with observational data would be necessary.

    ↳ astro-ph.COgr-qchep-phPRD(2021)·22 citations
20. 20*

    Machine Learning the 6th Dimension: Stellar Radial Velocities from 5D Phase-Space Correlations

    Adriana Dropulic🇺🇸 · Bryan Ostdiek🇺🇸 · Laura J. Chang🇺🇸 · Hongwan Liu🇺🇸 · Timothy Cohen🇺🇸 · Mariangela Lisanti🇺🇸

    The Gaia satellite will observe the positions and velocities of over a billion Milky Way stars. In the early data releases, the majority of observed stars do not have complete 6D phase-space information. In this Letter, we demonstrate the ability to infer the missing line-of-sight velocities until more spectroscopic observations become available. We utilize a novel neural network architecture that, after being trained on a subset of data with complete phase-space information, takes in a star's 5D astrometry (angular coordinates, proper motions, and parallax) and outputs a predicted line-of-sight velocity with an associated uncertainty. Working with a mock Gaia catalog, we show that the network can successfully recover the distributions and correlations of each velocity component for stars that fall within ~5 kpc of the Sun. We also demonstrate that the network can accurately reconstruct the velocity distribution of a kinematic substructure in the stellar halo that is spatially uniform, even when it comprises a small fraction of the total star count.

    ↳ astro-ph.GAhep-phphysics.data-anApJL(2021)·6 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.