Tue·Jun 28, 2022Tuesday·June 28, 2022

1. 01*

   xFitter: An Open Source QCD Analysis Framework. A resource and reference document for the Snowmass study

   The xFitter Developers' Team: H. Abdolmaleki🇮🇷 · S. Amoroso🇩🇪 · V. Bertone🇫🇷 · M. Botje🇩🇪 · D. Britzger🇩🇪 · S. Camarda🇨🇭 · A. Cooper-Sarkar🇬🇧 · J. Fiaschi🇬🇧 · F. Giuli🇨🇭 · A. Glazov🇩🇪 · C. Gwenlan🇬🇧 · F. Hautmann🇧🇪 and 10 other authors

   We provide an overview of the xFitter open-source software package, review the general capabilities of the program, and highlight applications relevant to the Snowmass study. An updated version of the program (2.2.0) is available on CERN GitLab, a and this has been updated to a C++ codebase with enhanced and extended features. We also discuss some of the ongoing and future code developments that may be useful for precision studies. We survey recent analyses performed by the xFitter developers' team including: W and Z production, photon PDFs, Drell-Yan forward-backward asymmetry studies, resummation of small-x contributions, heavy quark production, constraints on the strange PDF, determination of the pion PDF, and determination of the pion Fragmentation Functions. Finally, we briefly summarize selected applications of xFitter in the literature. The xFitter program is a versatile, flexible, modular, and comprehensive tool that can provide impact studies for possible future facilities. We encourage the use of xFitter, and welcome new contributions from the community.

   hep-ph66 citations
2. 02*

   Nucleon axial form factor at large momentum transfers

   Chen Chen🇨🇳 · Craig D. Roberts🇨🇳

   Using a Poincaré-covariant quark+diquark Faddeev equation and related symmetry-preserving weak interaction current, we deliver parameter-free predictions for the nucleon axialvector form factor, $G_A(Q^2)$, on the domain $0\le x=Q^2/m_N^2\le 10$, where $m_N$ is the nucleon mass. We also provide a detailed analysis of the flavour separation of the proton $G_A$ into contributions from valence $u$ and $d$ quarks; and with form factors available on such a large $Q^2$ domain, predictions for the flavour-separated axial-charge light-front transverse spatial density profiles. Our calculated axial charge ratio $g_A^d/g_A^u=-0.32(2)$ is consistent with available experimental data and markedly larger in magnitude than the value typical of nonrelativistic quark models. The value of this ratio is sensitive to the strength of axialvector diquark correlations in the Poincaré-covariant nucleon wave function. Working with a realistic axialvector diquark content, the $d$ and $u$ quark transverse density profiles are similar. Some of these predictions could potentially be tested with new data on threshold pion electroproduction from the proton at large $Q^2$.

   hep-phhep-exhep-latnucl-ex+1EPJA(2022)·22 citations
3. 03*

   Possible Universal Limit for Valence Parton Distributions

   Christopher Leon🇺🇸 · Misak M. Sargsian🇺🇸

   We report the observation of the existence of a possible universal limit for valence parton distributions that should exist once partonic degrees of freedom are relevant for high energy scattering from strongly interacting bound systems like a nucleon, meson or a few nucleon system at very short distances. Our observation is based on the notion that the Bjorken x weighted valence parton distribution function has a peak, $x_p$, that characterizes the average momentum fraction carried out by the valence quarks in the system. Within the residual mean-field model of the valence quark distribution we found that $x_p$ has an upper limit: $x_p\le \frac{1}{2(n_V-1)}$, where $n_V$ is the number of valence quarks which can be considered in the cluster embedded in the strongly interacting environment of the bound system. The existence of such a limit imposes a new constraint on choosing the starting resolution scale $Q_0$ for PDFs. Our prediction for the nucleon is that $x_p{\mid }_{Q\to Q_0}\le \frac{1}{4}$, which is in agreement with all the available valence PDFs that employ the standard approach for selecting starting $Q_0$. We also demonstrate how the existence of this limit can be used to check the onset of quark-clusters in short range nucleon correlations in nuclei.

   hep-phNPA(2025)·1 citation
4. 04*

   The analogy of the Lorentz-violating fermion-gravity and fermion photon couplings

   Cheng Ye🇨🇳 · Zhi Xiao🇨🇳

   By adopting a methodology proposed by R.J. Adler \etl, we study the interesting analogy between the fermion-gravity and the fermion-electromagnetic interactions in the presence of the minimal Lorentz-violating (LV) fermion coefficients. The one-fermion matrix elements of gravitational interaction (OMEGI) are obtained with a prescribed Lense-Thirring (LT) metric assuming test particle assumption. Quite distinct from the extensively studied linear gravitational potential, the LT metric is an essentially curved metric, and thus reveals the anomalous LV matter-gravity couplings as a manifestation of the so-called gravito-magnetic effects, which go beyond the conventional equivalence principle predictions. By collecting all the spin-dependent operators from the OMEGI with some reasonable assumptions, we get a LV non-relativistic Hamiltonian, from which we derive the anomalous spin precession and gravitational acceleration due to LV. Combined these results with certain spin gravity experiments, we get some rough bounds on several LV parameters, such as $|3\overrightarrow{\stackrel{~}{H}}-2\vec{b}|\le 1.46\times 10^{-5}\mathrm{eV}$, with some ad hoc assumptions.

   hep-phgr-qcPRD(2022)·3 citations
5. 05*

   Shear induced polarization: Collisional contributions

   Shu Lin🇨🇳 · Ziyue Wang🇨🇳

   It has been realized that thermal shear plays a similar role as thermal vorticity in polarizing spin of particles in heavy ion collisions. We point out that shear has a fundamental difference that it leads to particle redistribution in the medium. The redistribution gives rise to an additional contribution to spin polarization through the self-energy, which is parametrically the same order as the one considered so far in the literature. The self-energy contribution is in general gauge dependent. We introduce double gauge links stretching along the Schwinger-Keldysh contour to restore gauge invariance. We also generalize the straight path to adapt to the Schwinger-Keldysh contour. We find another contribution associated with the gauge link, which is also parametrically the same order. We illustrate the two contributions with a massive probe fermion in massless QED plasma with shear. A modest suppression of spin polarization is found from the combined contributions when the probe fermion has momentum much greater than the temperature.

   hep-phcond-mat.mes-hallnucl-exnucl-thJHEP(2022)·32 citations
6. 06*

   Non-minimal Coupling Inflation and Dark Matter under the ${\mathbb{Z}}_3$ Symmetry

   Wei Cheng🇨🇳 · Xuewen Liu🇨🇳 · Ruiyu Zhou🇨🇳

   We study the cosmological inflation and dark matter (DM) in a unified way within a $Z_3$ complex scalar model. The real and imaginary parts of the complex scalar act as the inflaton and DM respectively. The slow-rolling inflation with non-minimal coupling in both the metric and Palatini formalisms can be realized. We examine the whole parameters space by fully considering the theoretical and experimental constraints. We find that in the low-energy scale, the DM relic density and the DM-nucleon direct scattering experiments favor the mixing angle $|\theta |\lesssim 0.25$, the DM mass $m_{\chi }\gtrsim 80\mathrm{GeV}$, and the mass of Higgs-like scalar $m_{h_2}\gtrsim 300\mathrm{GeV}$. In the high-energy scale, after further considering the cosmological constraints of the scalar spectral index and the tensor-to-scalar ratio for the two forms of inflation, the scalar spectral indices are both $\sim 0.965$, the non-minimum coupling coefficients are $\sim 10^4$ and $\sim 10^9$, and the tensor-to-scalar ratios are $\sim 10^{-3}$ and $\lesssim 10^{-11}$ respectively, which suggests that the inflation under the two formalisms can be distinguished by measuring the tensor-to-scalar ratio with higher precision.

   hep-phastro-ph.HEJCAP(2023)·9 citations
7. 07*

   Lepton mass matrix from double covering of $A_4$ modular flavor symmetry

   Hiroshi Okada🇰🇷 · Yuta Orikasa🇨🇿

   We study a double covering of modular $A_4$ flavor symmetry in which we construct lepton models in cases of canonical seesaw and radiative seesaw models. Through $\chi$ square numerical analysis, we show some predictions for the cases, depending on normal and inverted hierarchies.

   hep-phCPC(2022)·17 citations
8. 08*

   Chiral $Z^{\prime }$ in FASER, FASER2, DUNE, and ILC beam dump experiments

   Kento Asai🇯🇵 · Arindam Das🇯🇵 · Jinmian Li🇨🇳 · Takaaki Nomura🇨🇳 · Osamu Seto🇯🇵

   The origin of neutrino mass is a big unsolved problem of the Standard Model (SM) that motivate us to consider beyond the SM (BSM) scenarios where SM-singlet right-handed neutrinos (RHNs) are introduced to explain the origin of the light neutrino masses through the seesaw mechanism. There is a variety of ways which could lead us to this goal and one of them is a general U$(1)$ extension of the SM. In this scenario, three SM-singlet RHNs are introduced to cancel the gauge and mixed gauge gravity anomalies. After anomaly cancellation, we notice that the left- and right-handed charged fermions are differently charged under the general U$(1)$ gauge group evolving a chiral scenario. After the breaking of the general U$(1)$ symmetry, a neutral BSM gauge boson $(Z^{\prime })$ acquires mass and it is a free parameter. Such $Z^{\prime }$, being lighter than $5$ GeV, could be probed at the intensity and lifetime frontiers like FASER, FASER2, DUNE, and ILC beam dump experiments. The estimated bounds are needed to be compared with the existing bounds. We find that existing constraints from Orsay, Nomad, PS191, KEK, LSND, CHARM experiments, and cosmological scenario like SN1987A can be compared in our case once estimated for chiral scenarios. Finally, we compare the parameter spaces showing viable ones that could be probed by FASER, FASER2, DUNE, and ILC beam dump experiments and already excluded regions from Orsay, Nomad, PS191, KEK, LSND, CHARM, and SN1987A for a chiral scenario.

   hep-phPRD(2022)·39 citations
9. 09*

   Muon ($g-2$) in $U(1{)}_{L_{\mu }-L_{\tau }}$ Scotogenic Model Extended with Vector like Fermion

   Simran Arora🇮🇳 · Monal Kashav🇮🇳 · Surender Verma🇮🇳 · B. C. Chauhan🇮🇳

   The latest results of anomalous muon magnetic moment at Fermilab show a discrepancy of 4.2 $\sigma$ between the Standard Model (SM) prediction and experimental value. In this work, we revisit $U(1{)}_{L_{\mu }-L_{\tau }}$ symmetry with in the paradigm of scotogenic model which explains muon ($g-2$) and neutrino mass generation, simultaneously. The mass of new gauge boson $M_{Z_{\mu \tau }}$ generated after the spontaneous symmetry breaking of $U(1{)}_{L_{\mu }-L_{\tau }}$ is constrained, solely, in light of the current neutrino oscillation data to explain muon ($g-2$). In particular, we have obtained two regions I and II, around 150 MeV and 500 MeV, respectively, in $M_{Z_{\mu \tau }}-g_{\mu \tau }$ plane which explain the neutrino phenomenology. Region I is found to be consistent with muon neutrino trident (MNT) bound ($g_{\mu \tau }$ $\le$ $10^{-3}$) to explain muon ($g-2$), however, region II violates it for mass range $M_{Z_{\mu \tau }}>300$ MeV. We, then, extend the minimal gauged scotogenic model by a vector like lepton (VLL) triplet ${\psi }_T$. The mixing of ${\psi }_T$ with inert scalar doublet $\eta$ leads to chirally enhanced positive contribution to muon anomalous magnetic moment independent of $Z_{\mu \tau }$ mass. Furthermore, we have, also, investigated the implication of the model for $0\nu \beta \beta$ decay and $CP$ violation. The non-observation of $0\nu \beta \beta$ decay down to the sensitivity of 0.01 eV shall refute the model. The model, in general,is found to be consistent with both $CP$ conserving and $CP$ violating solutions.

   hep-phPhys.Scripta(2023)·8 citations
10. 10*

    Detection of 16 small glitches in 9 pulsars

    Zu-Rong Zhou🇨🇳 · Jing-Bo Wang🇨🇳 · Na Wang🇨🇳 · Jian-Ping Yuan🇨🇳 · Fei-Fei Kou🇨🇳 · Shi-Jun Dang🇨🇳

    Timing observations from the Nanshan 26-m radio telescope for nine pulsars between 2000 and 2014 have been used to search for glitches. The data span for nine pulsars ranges from 11.6 to 14.2 years. From the total of 114 yr of pulsar rotational history, 16 new glitches were identified in 9 pulsars. Glitch parameters were measured by fitting the timing residuals data. All 16 glitches have a small fractional size. Six new glitches have been detected in PSR J1833-0827, making it another frequent glitching pulsar. Some of the 16 glitches may experience exponential or linear recovery, but it is unlikely for us to make further analyses with the large gap in the data set. All the glitch rates obtained from Nanshan are higher than that from Jodrell Bank Observatory. The small glitch size and high glitch rate could possibly attribute to the high observation cadence.

    hep-phastro-ph.GAastro-ph.HEastro-ph.SRRes.Astron.Astrophys.(2022)·4 citations
11. 11*

    Minkowski's lost legacy and hadron electromagnetism

    Yang Li🇨🇳 · Wen-bo Dong🇨🇳 · Yi-liang Yin🇨🇳 · Qun Wang🇨🇳 · James P. Vary🇺🇸

    We revisit Minkowski's lost legacy on relativistic electromagnetism in order to resolve long-standing puzzles over the charge distribution of relativistic systems like hadrons. Hadrons are unique relativistic electromagnetic systems characterized by their comparable size and Compton wavelength $r_h\sim {\lambda }_C$. As such, it was recently realized that the traditional Sachs definition of the charge distribution based on a non-relativistic formula is invalid. We explain that this is the same problem pursued by Lorentz, Einstein and others, on the electromagnetism of a moving body. We show how various charge distributions proposed in hadronic physics naturally emerge as the multipole moment densities in the macroscopic theory of relativistic electromagnetism.

    hep-phnucl-thphysics.class-phquant-phPLB(2023)·21 citations
12. 12*

    Adler function, Bjorken Sum Rule and Crewther-Broadhurst-Kataev relation with generic fermion representations at order $O({\alpha }_s^4)$

    K. · G. Chetyrkin

    We compute the nonsinglet Adler $D$-function and the coefficient function for Bjorken polarized sum rules $S^{Bjp}$ at order $O({\alpha }_s^4)$ in an extended QCD model with arbitrary number of fermion representations. The Crewther-Broadhurst-Kataev (CBK) relation in this order is confirmed.

    hep-phNPB(2022)·7 citations
13. 13*

    Analytic structure of the MNS matrix with diagonal reflection symmetries

    Masaki J.S. Yang🇯🇵

    In this paper, we survey the analytic structure of the MNS matrix with diagonal reflection symmetries. If the mass matrix of charged leptons $m_e$ is hierarchical (i.e., $|(m_e{)}_{33}|\simeq m_{\tau }\gg |(m_e{)}_{1i,j1}|$), by neglecting the 1-3 mixing of $m_e$, the MNS matrix is represented by four parameters and several sign degrees of freedom. By substituting the three observed mixing angles ${\theta }_{ij}$ as input parameters, the Dirac phase $\delta$ and the Majorana phases ${\alpha }_{2,3}$ are represented by functions of the 1-2 mixing of charged leptons $s_e$. The effective mass of double beta decay $m_{ee}$ is also displayed as a function of $s_e$ and the lightest neutrino mass $m_{1\mathrm{or}3}$. Because the generalized CP symmetries restrict the effective mass to near the maximum or minimum value in the whole parameter region, several scenarios are suggested to be excluded by the latest limit of the KAMLAND-Zen collaboration.

    hep-ph0 citations
14. 14*

    Regulator scheme dependence of the chiral phase transition at high densities

    Konstantin Otto🇩🇪 · Christopher Busch🇩🇪 · Bernd-Jochen Schaefer🇩🇪

    A common feature of recent functional renormalization group investigations of effective low-energy QCD is the appearance of a back-bending behavior of the chiral phase transition line at low temperatures together with a negative entropy density in the symmetric regime. The regulator scheme dependence of this phenomenon and the necessary modifications at finite densities are analyzed within a two-flavor quark-meson model. The flows at finite densities for three different regulators of three- or four-dimensional momenta are confronted to each other. It is found that the back-bending behavior and the negative entropy density can be traced back to the explicit momentum dependence of the regulator shape function. While it persists for the often-used three-dimensional flat regulator, it vanishes for Callan-Symanzik type regulators. This points to truncation artifacts in the lowest order of the derivative expansion. A careful theoretical as well as numerical exploration is given.

    hep-phhep-thnucl-thPRD(2022)·26 citations
15. 15*

    Dark Matter perspective of Left-Right symmetric gauge model

    Sanchari Bhattacharyya🇮🇳 · Anindya Datta🇮🇳

    We consider an incarnation of left-right symmetric model with a local gauge symmetry of $SU(3{)}_C\otimes SU(2{)}_L\otimes U(1{)}_L\otimes SU(2{)}_R\otimes U(1{)}_R$. Heavy scalars and fermions present in the {\bf 27} of $E_6$ are included in the matter sector along with the Standard Model fermions. Two such colour singlet fermions, $N$ and $l_S$, transforming as bi-doublet and singlet under $SU(2)$s respectively, can be potential candidates for Dark Matter (DM). Assignment of $U(1)$ charges for the matter fields restricts some of the exotic fermions to interact with the SM fermions. We study in some details the prospect of such fermionic dark matters by calculating relic densities and direct detection cross-sections by treating these particles as stand alone relic particles in turn. $N$, when treated as relic particle, would produce a direct-detection cross-section very high compared to the experimental upper limits. However, the interaction rate of $N$ can be controlled by introducing a dimension-6 operator involving two $N$ fields and two SM fermions and appropriately choosing the coupling constant. This in turn, makes the interaction rate of $N$ very high and yields a small relic density. On the other hand, $l_S$ for some chosen mass window, can give us right amount of relic, but its direct detection cross-section is too small. Keeping these in mind, we propose two-component model of DM, where both $N$ and $l_S$ contribute to the relic density, albeit with unequal proportion while the direct detection cross-section limits can be satisfied mainly by $N$ in presence of an extra dimension-6 interaction. We derive limits on such an interaction from XENON experiment.

    hep-phNPB(2023)·7 citations
16. 16*

    The stability analysis of the extended singlet scalar model with two high scale minima

    Najimuddin Khan🇮🇳

    We study the simplest viable dark matter (DM) model with a real singlet scalar, vector-like singlet, and doublet fermions. The Yukawa couplings associated with the fermion sector are important in obtaining the current DM relic density through Freeze-out and Freeze-in mechanisms. In addition to the standard model-like high scale minima along the Higgs field, we find other high scale minima along the singlet scalar field direction. The other minima appears due to the renormalisation group evolutions of the couplings involving the gauge sector, Higgs portal, and the new Yukawa sector. A detailed study of the parameter space identifying the region of electroweak vacuum stability and metastability along different directions of the scalar field is carried out using different phase diagrams.

    hep-phNPB(2022)·3 citations
17. 17*

    Nonperturbative effects in neutrino magnetic moments

    Feng-Zhi Chen🇨🇳 · Min-Di Zheng🇨🇳 · Hong-Hao Zhang🇨🇳

    In this paper, we calculate the QCD nonperturbative contributions of the neutrino-quark tensor operators to the neutrino magnetic moments by matching onto the chiral perturbation theory at low energies. These nonperturbative contributions can be compared to the perturbative ones, which are induced from one-loop mixing when performing the renormalization group evolutions from $\mu =m_W$ down to $\mu =2\mathrm{GeV}$. We then constrain the dipole and tensor Wilson coefficients of the low-energy neutrino effective field theory (LNEFT) separately from the neutrino-electron scattering with Borexino data and coherent elastic neutrino-nucleus scattering (CE$\nu$NS) with COHERENT data to show the competition between these two contributions, at the renormalization scales $\mu =2\mathrm{GeV}$ and $\mu =m_W$ in the $\overline{\mathrm{MS}}$ scheme. In the neutrino-electron scattering, it is found that the nonperturbative contributions dominate for the coefficients involving up and down quarks, while they are expected to be of the same order of magnitude as the perturbative contributions for the coefficients involving strange quark. As for constraints in the CE$\nu$NS, the tensor operators can contribute to the process through either direct or indirect way. As a result, the indirect contributions including nonperturbative and perturbative parts for all couplings become negligible in comparison with the direct ones. As the nonperturbative contributions crucially depend on the value of $c_T$, its inputs will affect the extraction of limits on the tensor LNEFT Wilson coefficients. We compute the upper bounds on these coefficients with $c_T$ quoting from the model and lattice estimates.

    hep-phnucl-thPRD(2022)·4 citations
18. 18*

    Gluonic nature of the newly observed state $X(2600)$

    Sheng-Qi Zhang🇨🇳 · Bing-Dong Wan🇨🇳 · Liang Tang🇨🇳 · Cong-Feng Qiao🇨🇳

    Motivated by the newly observed resonance $X(2600)$ by BESIII Collaboration, we examine the trigluon glueball interpretation for it in the framework of QCD sum rules. We evaluate the mass spectra of the trigluon glueballs with quantum numbers $0^{-+}$ and $2^{-+}$ up to dimension 8 condensate in the operator product expansion. Our numerical results indicate that the mass of the $2^{-+}$ trigluon glueball is about $2.66\pm 0.06$ GeV, which is consistent with the mass of the X(2600) within the uncertainties, while $0^{-+}$ has a mass of $2.01\pm 0.14$ GeV. The possible decay channels of the $2^{-+}$ state are analyzed, which are crucial in decoding $X(2600)$'s internal structure and are hopefully measurable in BESIII, BEllEII, PANDA, and LHCb experiments.

    hep-phPRD(2022)·26 citations
19. 19*

    Diffractive deep inelastic scattering at NLO in the dipole picture: the $q\bar{q}g$ contribution

    G. Beuf🇵🇱 · H. Hänninen🇫🇮 · T. Lappi🇫🇮 · Y. Mulian🇪🇸 · H. Mäntysaari🇫🇮

    We calculate the contribution from the $q\bar{q}g$ state production to the diffractive cross sections in deep inelastic scattering at high energy. The obtained cross section is finite by itself and a part of the full next-to-leading order result for the diffractive structure functions. We perform the calculation in exact kinematics in the eikonal limit, and show that the previously known high-$Q^2$ and large $M_X^2$ results for the structure functions can be extracted from our results in the appropriate limits. We furthermore discuss the steps required to obtain the full next-to-leading order results for the structure functions.

    hep-phnucl-thPRD(2022)·51 citations
20. 20*

    W-exchange contribution to the decays ${\Xi }_{cc}^{++}\to {\Xi }_c^{+(\prime )}{\pi }^{+}$ using light-cone sum rules

    Yu-Ji Shi🇩🇪 · Zhen-Xing Zhao🇨🇳 · Ye Xing🇨🇳 · Ulf-G. Meißner🇩🇪

    We calculate the W-exchange contribution to the ${\Xi }_{cc}^{++}\to {\Xi }_c^{+(\prime )}{\pi }^{+}$ decay using light-cone sum rules. The two-particle light-cone distribution amplitudes of the pion are used as non-perturbative input for the sum rules calculation, and the perturbative kernel is calculated at the leading order. We obtain the corresponding decay branching fractions by combining our W-exchange amplitudes with the factorizable amplitudes given by various theoretical methods from the literature. It is shown that with the factorizable amplitudes from heavy quark effective theory, we obtain the branching fraction ratio $\mathcal{B}({\Xi }_{cc}^{++}\to {\Xi }_c^{+\prime }{\pi }^{+})/\mathcal{B}({\Xi }_{cc}^{++}\to {\Xi }_c^{+}{\pi }^{+})=1.42\pm 0.78$, which is consistent with the experimental value of $1.41\pm 0.17\pm 0.1$.

    hep-phhep-exPRD(2022)·11 citations
21. 21*

    A Survey of Family Unification Models with Bifundamental Matter

    Elijah Sheridan🇺🇸 · Thomas W. Kephart🇺🇸

    Extensions of the Standard Model have been attempted from the bottom up and from the top down yet there remains a largely unexplored middle ground. In this paper, using the Mathematica package LieART, we exhaustively enumerate embeddings of the Standard Model within the class of theories with bifundamental fermions in product gauge group SU(a)XSU(b)XSU(c) with no more generators than E6, while achieving SM family unification rather than replication. We incorporate simple phenomenological constrains and find 151 unique models, including 9 that have only vector-like particle content beyond-the-Standard Model (BSM) particles, which we conjecture belong to 5 infinite families of such models. We describe the potentially most viable models: namely, the 9 with strictly vector-like BSM content along with the 29 models we found with no more than 30 additional BSM chiral particles. These include models with fractional electric charge color singlets, and hence magnetic monopoles with multiple Dirac charge. This latter collection of models predicts chiral particles with masses near the electroweak scale accessible to current and future collider experiments.

    hep-phhep-thNPB(2023)·3 citations
22. 22*

    Kinematic Variables and Feature Engineering for Particle Phenomenology

    Roberto Franceschini🇮🇹 · Doojin Kim🇺🇸 · Kyoungchul Kong🇺🇸 · Konstantin T. Matchev🇺🇸 · Myeonghun Park🇰🇷 · Prasanth Shyamsundar🇺🇸

    Kinematic variables have been playing an important role in collider phenomenology, as they expedite discoveries of new particles by separating signal events from unwanted background events and allow for measurements of particle properties such as masses, couplings, spins, etc. For the past 10 years, an enormous number of kinematic variables have been designed and proposed, primarily for the experiments at the Large Hadron Collider, allowing for a drastic reduction of high-dimensional experimental data to lower-dimensional observables, from which one can readily extract underlying features of phase space and develop better-optimized data-analysis strategies. We review these recent developments in the area of phase space kinematics, summarizing the new kinematic variables with important phenomenological implications and physics applications. We also review recently proposed analysis methods and techniques specifically designed to leverage the new kinematic variables. As machine learning is nowadays percolating through many fields of particle physics including collider phenomenology, we discuss the interconnection and mutual complementarity of kinematic variables and machine learning techniques. We finally discuss how the utilization of kinematic variables originally developed for colliders can be extended to other high-energy physics experiments including neutrino experiments.

    hep-phhep-exRMP(2023)·32 citations
23. 23*

    Neutrino Properties and Interactions

    Pedro A. N. Machado🇺🇸

    In this chapter we present basic concepts of neutrino physics. We start with a brief introduction to the standard model electroweak sector, followed by calculations of some relevant neutrino interaction cross sections. We obtain the oscillation formalism from the Dirac equation, alongside with a self-contained derivation of matter effects from the standard model electroweak lagrangian. Some key features of neutrino oscillation phenomenology are discussed as well. We then review the most precise oscillation measurements and finalize with some broad discussion of the current open questions in neutrino physics.

    hep-phastro-ph.COhep-ex5 citations
24. 24*

    The muon g-2 and lattice QCD hadronic vacuum polarization may point to new, long-lived neutral hadrons

    Glennys R. Farrar🇺🇸

    The experimental value of g-2 of the muon is larger by $4.2\sigma$ than the Standard Model prediction based on the hadronic vacuum polarization contribution (HVP) determined from the measured R-ratio, $\sigma (e^{+}{e}^{-}\to hadrons)/\sigma (e^{+}{e}^{-}\to {\mu }^{+}{\mu }^{-})$; the HVP calculated in lattice QCD also significantly exceeds the measured R-ratio value. We show here that these discrepancies can be explained by an undetected contribution to $e^{+}{e}^{-}\to hadrons$ as could arise from production of neutral, long-lived hadrons which have not previously been identified. We suggest two candidates for the new hadrons and propose several experimental tests.

    hep-phhep-lat6 citations
25. 25*

    Chiral symmetry: An analytic $SU(3)$ unitary matrix

    M.R. Robilotta🇧🇷

    The $SU(2)$ unitary matrix $U$ employed in hadronic low-energy processes has both exponential and analytic representations, related by $U=\exp \left[i\tau \cdot \hat{\pi }\theta \right]=\cos \theta I+i\tau \cdot \hat{\pi }\sin \theta$. One extends this result to the $SU(3)$ unitary matrix by deriving an analytic expression which, for Gell-Mann matrices $\lambda$, reads $U=\exp \left[i\mathbf{v}\cdot \lambda \right]=\left[\left(F+\frac{2}{3}G\right)I+\left(H\hat{\mathbf{v}}+\frac{1}{\sqrt{3}}G\hat{\mathbf{b}}\right)\cdot \lambda \right]+i\left[\left(Y+\frac{2}{3}Z\right)I+\left(X\hat{\mathbf{v}}+\frac{1}{\sqrt{3}}Z\hat{\mathbf{b}}\right)\cdot \lambda \right]$, with $v_i=[v_1,\cdots v_8]$, $b_i=d_{ijk}{v}_j{v}_k$, and factors $F,\cdots Z$ written in terms of elementary functions depending on $v=|\mathbf{v}|$ and $\eta =2d_{ijk}{\hat{v}}_i{\hat{v}}_j{\hat{v}}_k/3$. This result does not depend on the particular meaning attached to the variable $\mathbf{v}$ and the analytic expression is used to calculate explicitly the associated left and right forms. When $\mathbf{v}$ represents pseudoscalar meson fields, the classical limit corresponds to $⟨0|\eta |0⟩\to \eta \to 0$ and yields the cyclic structure $U=\left\{\left[\frac{1}{3}\left(1+2\cos v\right)I+\frac{1}{\sqrt{3}}\left(-1+\cos v\right)\hat{\mathbf{b}}\cdot \lambda \right]+i\left(\sin v\right)\hat{\mathbf{v}}\cdot \lambda \right\}$, which gives rise to a tilted circumference with radius $\sqrt{2/3}$ in the space defined by $I$, $\hat{\mathbf{b}}\cdot \lambda$, and $\hat{\mathbf{v}}\cdot \lambda$. The axial transformations of the analytic matrix are also evaluated explicitly.

    hep-phhep-thmath-phmath.MPPRD(2022)·1 citation
26. 26*

    Hints of dark photon dark matter from observations and hydrodynamical simulations of the low-redshift Lyman-$\alpha$ forest

    James S. Bolton🇬🇧 · Andrea Caputo🇮🇱 · Hongwan Liu🇺🇸 · Matteo Viel🇮🇹

    Recent work has suggested that an additional $\lesssim 6.9\mathrm{eV}$ per baryon of heating in the intergalactic medium is needed to reconcile hydrodynamical simulations with Lyman-$\alpha$ forest absorption line widths at redshift $z\simeq 0.1$. Resonant conversion of dark photon dark matter into low frequency photons is a viable source of such heating. We perform the first hydrodynamical simulations including dark photon heating and show that dark photons with mass $m_{A^{\prime }}\sim 8\times 10^{-14}\mathrm{eV}{\mathrm{c}}^{-2}$ and kinetic mixing $ϵ\sim 5\times 10^{-15}$ can alleviate the heating excess. A prediction of this model is a non-standard thermal history for underdense gas at $z\gtrsim 3$.

    hep-phastro-ph.COPRL(2022)·30 citations
27. 27*

    First Evaluation of Meson and $\tau$ lepton Spectra and Search for Heavy Neutral Leptons at ILC Beam Dump

    Mihoko M. Nojiri🇯🇵 · Yasuihito Sakaki🇯🇵 · Kohsaku Tobioka🇺🇸 · Daiki Ueda🇨🇳

    A beam dump experiment can be seamlessly added to the {proposed} International Linear Collider (ILC) program because the high energy electron beam should be dumped after the collision point. The ILC beam dump experiment will provide an excellent opportunity to search for new long-lived particles. Since many of them can be produced by a rare decay of standard model particles, we evaluate spectra of the mesons and $\tau$ lepton at the decay based on the PHITS and PYTHIA8 simulations. As a motivated physics case, we study the projected sensitivity of heavy neutral leptons at the ILC beam dump experiment. The heavy neutral leptons can also be produced via deep inelastic scattering and $Z$ boson decay at the ILC main detector, which we include in the projection. With the multi-track signal, the reach would be greatly extended in mass and coupling, even compared with the other proposed searches.

    hep-phhep-exJHEP(2022)·12 citations
28. 28*

    Spinning Sum Rules for the Dimension-Six SMEFT

    Grant N. Remmen🇺🇸 · Nicholas L. Rodd🇨🇭

    We construct new dispersive sum rules for the effective field theory of the standard model at mass dimension six. These spinning sum rules encode information about the spin of UV states: the sign of the IR Wilson coefficients carries a memory of the dominant spin in the UV completion. The sum rules are constructed for operators containing scalars and fermions, although we consider the dimension-six SMEFT exhaustively, outlining why equivalent relations do not hold for the remaining operators. As with any dimension-six dispersive argument, our conclusions are contingent on the absence of potential poles at infinity, so-called boundary terms, and we discuss in detail where these are expected to appear. There are a number of phenomenological applications of spinning sum rules, and as an example we explore the connection to the Peskin-Takeuchi parameters and, more generally, the set of oblique parameters in universal theories.

    hep-phhep-thJHEP(2022)·31 citations
29. 29*

    Dark radiation constraints on portal interactions with hidden sectors

    Peter Adshead🇺🇸 · Pranjal Ralegankar🇺🇸 · Jessie Shelton🇺🇸

    We update dark radiation constraints on millicharged particle (MCP) and gauged baryon-number-minus-lepton-number ($B-L$) extensions of the Standard Model (SM). In these models, a massive SM gauge singlet mediator couples the SM plasma to additional SM-singlet light degrees of freedom. In the early Universe, these new light particles are populated via the interaction of the SM with the MCP, or the new $B-L$ gauge boson, and act as dark radiation. The presence of dark radiation in the early Universe is tightly constrained by current and upcoming cosmic microwave background (CMB) measurements. We update bounds on MCPs from current measurements of $N_{\mathrm{eff}}$ and show that future CMB experiments will be able to rule out or discover the extended MCP model invoked to explain the EDGES anomaly. Our analysis of the gauged $B-L$ model goes beyond previous studies by including quantum-statistical and out-of-equilibrium effects. Further, we account for the finite lifetime of the $B-L$ gauge boson, which boosts the subsequent right-handed neutrino energy density. We also develop a number of approximations and techniques for simplifying and solving the relevant Boltzmann equations. We use our approximations to develop a lower bound on the radiation density in a generic hidden sector with a light relic that is insensitive to the details of the hidden sector, provided the mediator interacts more strongly with the hidden sector than with the SM.

    hep-phastro-ph.COJCAP(2022)·49 citations
30. 30*

    Resonant Electric Probe to Axionic Dark Matter

    Junxi Duan🇨🇳 · Yu Gao🇨🇳 · Chang-Yin Ji🇨🇳 · Sichun Sun🇨🇳 · Yugui Yao🇨🇳 · Yun-Long Zhang🇨🇳

    The oscillating light axion field is known as wave dark matter. We propose an LC-resonance enhanced detection of the narrow band electric signals induced by the axion dark matter using a solenoid magnet facility. We provide full 3D electromagnetic simulation results for the signal electric field. The electric signal is enhanced by the high $Q$-factor of a resonant LC circuit and then amplified and detected by the state-of-the-art cryogenic electrical transport measurement technique. The cryogenic amplifier noise is the dominant noise source in the proposed detection system. We estimate that the detection system can have a promising sensitivity to axion dark matter with mass below $10^{-6}$ eV. The projected sensitivities improve with the size of the magnetic field, and the electric signal measurement can be potentially sensitive to the quantum chromodynamics (QCD) axion with $g_{a\gamma }\sim 10^{-16}$ GeV${}^{-1}$ around $m_a\sim 10^{-8}$eV, with a multi-meter scale magnetized region. This limit is around five orders of magnitude below the current constraint from the cosmic rays.

    hep-phastro-ph.COcond-mat.mes-hallhep-ex+1PRD(2023)·11 citations
31. 31*

    Emergent Metric Space-Time from Matrix Theory

    Suddhasattwa Brahma🇬🇧 · Robert Brandenberger🇨🇦 · Samuel Laliberte🇨🇦

    The IKKT matrix model yields an emergent space-time. We further develop these ideas and give a proposal for an emergent metric. Based on previous numerical studies of this model, we provide evidence that the emergent space-time is continuous and infinite in extent, both in space and in time, and that the metric is spatially flat. The time evolution describes the transition from a string-theoretic emergent phase to a phase in which the $SO(9)$ symmetry of the model is spontaneously broken to $SO(6)\times SO(3)$, with three dimensions of space expanding, becoming classical and at later times evolving like in a radiation-dominated universe, and the remaining six dimensions of space stabilized at the string scale. We speculate on how this analysis can be extended to yield an early universe cosmology which, in addition to the above-mentioned properties, also leads to a roughly scale-invariant spectrum of cosmological fluctuations and gravitational waves.

    ↳ hep-thastro-ph.COgr-qchep-phJHEP(2022)·38 citations
32. 32*

    First search for the weak radiative decays ${\Lambda }_c^{+}\to {\Sigma }^{+}\gamma$ and ${\Xi }_c^0\to {\Xi }^0\gamma$

    Belle Collaboration: Y. Li · C. P. Shen🇨🇳 · I. Adachi🇯🇵 · H. Aihara🇯🇵 · D. M. Asner🇺🇸 · V. Aulchenko🇷🇺 · T. Aushev🇷🇺 · V. Babu🇩🇪 · P. Behera🇮🇳 · K. Belous🇷🇺 · J. Bennett🇺🇸 · M. Bessner🇺🇸 and 177 other authors

    We present the first search for the weak radiative decays ${\Lambda }_c^{+}\to {\Sigma }^{+}\gamma$ and ${\Xi }_c^0\to {\Xi }^0\gamma$ using a data sample of 980~fb${}^{-1}$ collected by the Belle detector operating at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider. There are no evident ${\Lambda }_c^{+}\to {\Sigma }^{+}\gamma$ or ${\Xi }_c^0\to {\Xi }^0\gamma$ signals. Taking the decays ${\Lambda }_c^{+}\to p{K}^{-}{\pi }^{+}$ and ${\Xi }_c^0\to {\Xi }^{-}{\pi }^{+}$ as normalization channels, the upper limits at 90\% credibility level on the ratios of branching fractions $\mathcal{B}({\Lambda }_c^{+}\to {\Sigma }^{+}\gamma )/\mathcal{B}({\Lambda }_c^{+}\to p{K}^{-}{\pi }^{+})<4.0\times 10^{-3}$ and $\mathcal{B}({\Xi }_c^0\to {\Xi }^0\gamma )/\mathcal{B}({\Xi }_c^0\to {\Xi }^{-}{\pi }^{+})<1.2\times 10^{-2}$ are determined. We obtain the upper limits at 90\% credibility level on the absolute branching fractions $\mathcal{B}({\Lambda }_c^{+}\to {\Sigma }^{+}\gamma )<2.6\times 10^{-4}$ and $\mathcal{B}({\Xi }_c^0\to {\Xi }^0\gamma )<1.8\times 10^{-4}$.

    ↳ hep-exhep-phPRD(2023)·11 citations
33. 33*

    Coherent states for trapped ions. Applications in quantum optics and precision measurements

    Bogdan M. Mihalcea🇷🇴

    The evolution of squeezed coherent states (CSs) of motion for trapped ions is investigated by applying the time dependent variational principle (TDVP) for the Schrödinger equation. The method is applied in case of Paul and combined traps, for which the classical Hamiltonian and equations of motion are derived. Hence, CS provide a natural framework to: (a) engineer quantum correlated states for trapped ions intended for ultraprecise measurements, (b) explore the mechanisms responsible for decoherence, and (c) investigate the quantum-classical transition.

    ↳ quant-phhep-phhep-thProc. of the Ninth Meeting on CPT and Lor…·1 citation
34. 34*

    Hydrodynamic attractor of noisy plasmas

    Zenan Chen🇨🇳 · Derek Teaney🇺🇸 · Li Yan🇨🇳

    We provide a generalized formulation of fluctuating hydrodynamics for the far-from-equilibrium noisy medium. As an example, we consider a noisy plasma experiencing Bjorken expansion, for which the leading order evolution is captured by hydrodynamic attractor of classical hydrodynamics, while the quadratic couplings of fluctuations are solved effectively via a generalized version of the hydrodynamic kinetic equation. In the far-from-equilibrium plasma, backreaction of hydrodynamic fluctuations results in renormalization of transport properties, as well as long time tails, of high orders. In particular, corresponding to a renormalized hydrodynamic attractor, evolution in a noisy plasma towards equilibrium becomes non-monotonic.

    ↳ nucl-thhep-phPRC(2023)·9 citations
35. 35*

    A New Order Parameter for the Higgs Transition in $SU(2)$-Higgs Theory

    Mridupawan Deka🇷🇺 · Sanatan Digal🇮🇳

    We investigate the Higgs transition within the four dimensional $SU(2)-$ gauge-Higgs model in search for an order parameter as a function of the Higgs field hopping parameter, $\kappa$, using Lattice technique. We measure the Higgs condensate after applying Landau Gauge Fixing and study the corresponding susceptibility, magnetization and fourth order Binder cumulant using four different spatial volumes with $N_{\tau }=2$. The computation is carried out with gauge coupling, ${\beta }_g=8$, for a range of scalar self-coupling, $\lambda =\{0.00010,0.00350\}$, with emphasis near the critical end-point. Finite size scaling analysis of the gauge fixed condensate and its cumulants agree with the standard $3$d Ising values $\nu =0.62997$, $\beta /\nu =0.518$, $\gamma /\nu =1.964$ at $\lambda =0.00150$. These results are in agreement with previous studies suggesting $3$d Ising universality class. The numerical results also indicate that, at the transition point, the gauge fixed condensate vanishes in the infinite volume limit.

    ↳ hep-lathep-phhep-thPRD(2023)·0 citations
36. 36*

    Inflation Driven by Non-Linear Electrodynamics

    H.B. Benaoum (American U., Sharjah)🇦🇪 · Genly Leon (Catolica del Norte U. and DUT, Durban)🇨🇱 · A. Ovgun (Eastern Mediterranean U.)🇹🇷 · H. Quevedo (Mexico U., ICN and Rome U.)🇲🇽

    We investigate the inflation driven by a nonlinear electromagnetic field based on an NLED lagrangian density ${\mathcal{L}}_{\text{nled}}=-Ff\left(F\right)$, where $f\left(F\right)$ is a general function depending on $F$. We first formulate an $f$-NLED cosmological model with a more general function $f\left(F\right)$ and show that all NLED models can be expressed in this framework; then, we investigate in detail two interesting examples of the function $f\left(F\right)$. We present our phenomenological model based on a new Lagrangian for NLED. Solutions to the field equations with the physical properties of the cosmological parameters are obtained. We show that the early Universe had no Big-Bang singularity, which accelerated in the past. We also investigate the qualitative implications of NLED by studying the inflationary parameters, like the slow-roll parameters, spectral index $n_s$, and tensor-to-scalar ratio $r$, and compare our results with observational data. Detailed phase-space analysis of our NLED cosmological model is performed with and without matter source. As a first approach, we consider the motion of a particle of unit mass in an effective potential. Our systems correspond to fast-slow systems for physical values of the electromagnetic field and the energy densities at the end of inflation. We analyze a complementary system using Hubble-normalized variables to investigate the cosmological evolution before the matter-dominated Universe.

    ↳ gr-qcastro-ph.COhep-phhep-thEPJC(2023)·18 citations
37. 37*

    Nonlocality and entropic uncertainty relations in neutrino oscillations

    Massimo Blasone🇮🇹 · Silvio De Siena🇮🇹 · Cristina Matrella🇮🇹

    Using the wave-packet approach to neutrino oscillations, we analyze Quantum-Memory-Assisted Entropic Uncertainty Relations and show that uncertainty and the Non-local Advantage of Quantum Coherence are anti-correlated. Furthermore, we explore the hierarchy among three different definitions of NAQC, those based on the l1-norm, relative entropy and skew information coherence measures, and we find that the coherence content detected by the l1-norm based NAQC overcomes the other two. The connection between QMA-EUR and NAQC could provide a better understanding of the physical meaning of the results so far obtained, and suggest a their extension to quantum field theory.

    ↳ quant-phhep-phhep-thEur.Phys.J.Plus(2022)·14 citations
38. 38*

    Quantum theory, thermal gradients and the curved Euclidean space

    S. Ganesh🇮🇳

    The Euclidean space, obtained by the analytical continuation of time, to an imaginary time, is used to model thermal systems. In this work, it is taken a step further to systems with spatial thermal variation, by developing an equivalence between the spatial variation of temperature in a thermal bath and the curvature of the Euclidean space. The variation in temperature is recast as a variation in the metric, leading to a curved Euclidean space. The equivalence is substantiated by analyzing the Polyakov loop, the partition function and the periodicity of the correlation function. The bulk thermodynamic properties like the energy, entropy and the Helmholtz free energy are calculated from the partition function, for small metric perturbations, for a neutral scalar field. The Dirac equation for an external Dirac spinor, traversing in a thermal bath with spatial thermal gradients, is solved in the curved Euclidean space. The fundamental behavior exhibited by the Dirac spinor eigenstate, may provide a possible mechanism to validate the theory, at a more basal level, than examining only bulk thermodynamic properties. Furthermore, in order to verify the equivalence at the level of classical mechanics, the geodesic equation is analyzed in a classical backdrop. The mathematical apparatus is borrowed from the physics of quantum theory in a gravity-induced space-time curvature. As spatial thermal variations are obtainable at QCD or QED energies, it may be feasible for the proposed formulation to be validated experimentally.

    ↳ hep-thgr-qchep-phmath-ph+2Int.J.Mod.Phys.A(2022)·4 citations
39. 39*

    Measurement of the cross-section ratio ${\sigma }_{\psi (2S)}/{\sigma }_{J/\psi (1S)}$ in exclusive photoproduction at HERA

    ZEUS Collaboration · I. Abt · M. Adamus · R. Aggarwal · V. Aushev · O. Behnke · A. Bertolin · I. Bloch · I. Brock · N.H. Brook · R. Brugnera · A. Bruni and 71 other authors

    The exclusive photoproduction reactions $\gamma p\to J/\psi (1S)p$ and $\gamma p\to \psi (2S)p$ have been measured at an $ep$ centre-of-mass energy of 318 GeV with the ZEUS detector at HERA using an integrated luminosity of 373 pb${}^{-1}$. The measurement was made in the kinematic range $30<W<180$ GeV, $Q^2<1$ GeV${}^2$ and $|t|<1$ GeV${}^2$, where $W$ is the photon--proton centre-of-mass energy, $Q^2$ is the photon virtuality and $t$ is the squared four-momentum transfer at the proton vertex. The decay channels used were $J/\psi (1S)\to {\mu }^{+}{\mu }^{-}$, $\psi (2S)\to {\mu }^{+}{\mu }^{-}$ and $\psi (2S)\to J/\psi (1S){\pi }^{+}{\pi }^{-}$ with subsequent decay $J/\psi (1S)\to {\mu }^{+}{\mu }^{-}$. The ratio of the production cross sections, $R={\sigma }_{\psi (2S)}/{\sigma }_{J/\psi (1S)}$, has been measured as a function of $W$ and $|t|$ and compared to previous data in photoproduction and deep inelastic scattering and with predictions of QCD-inspired models of exclusive vector-meson production, which are in reasonable agreement with the data.

    ↳ hep-exhep-phJHEP(2022)·13 citations
40. 40*

    Causality constraints on nonlinear supersymmetry

    Quentin Bonnefoy🇩🇪 · Gabriele Casagrande🇫🇷 · Emilian Dudas🇫🇷

    It is well-known that gravitino propagation in standard supergravities is free of any causality problems. However, two issues related to gravitino propagation were recently uncovered in specific supergravities with nonlinear supersymmetry. One of them concerns potential acausality/superluminality, whereas the second one arises from the vanishing of the sound speed at specific points during inflation. The former is famously related to positivity constraints on specific EFT operators, derived from dispersion relations on the energy-growing part of scattering amplitudes, and indeed we show that subluminality constraints for the gravitino are related via the equivalence theorem to positivity bounds in low-energy goldstino actions. However, the former are stronger, in the sense that they apply to functions of the scalar fields not only in the ground state, but for any field values such as those scanned by time-dependent solutions, unlike bounds derived from $2\to 2$ scattering amplitudes in the vacuum. We also argue that nontrivial causality constraints arise only in the case where nonlinear supersymmetry in the matter sector is encoded into superfield constraints which do not seem to arise from microscopic two-derivative lagrangians, in particular for the orthogonal constraint used to build minimal models of inflation in supergravity. This allows us to propose simple alternatives which maintain the minimality of the spectra and are causal in all points of the theory parameter space. We also discuss minimal supergravity models of inflation along these lines.

    ↳ hep-thastro-ph.COhep-phJHEP(2022)·5 citations
41. 41*

    The hadronic nucleus-nucleus cross section and the nucleon size

    Govert Nijs🇺🇸 · Wilke van der Schee🇨🇭

    Even though the total hadronic nucleus-nucleus cross section is among the most fundamental observables, it has only recently been measured precisely for lead-lead collisions at the LHC. This measurement implies the nucleon width should be below 0.7 fm, which is in contradiction with all known state-of-the-art Bayesian estimates. We study the implications of the smaller nucleon width on quark-gluon plasma properties such as the bulk viscosity. The smaller nucleon width dramatically improves the description of several triple-differential observables.

    ↳ nucl-thhep-phnucl-exPRL(2022)·53 citations
42. 42*

    Detecting Cosmic Strings with Lensed Fast Radio Bursts

    Huangyu Xiao🇺🇸 · Liang Dai🇺🇸 · Matthew McQuinn🇺🇸

    Correlated red noise recently reported from pulsar timing observations may be an indication of stochastic gravitational waves emitted by cosmic strings that formed during a primordial phase transition near the Grand Unification energy scale. Unfortunately, known probes of cosmic strings, namely the Cosmic Microwave Background anisotropies and string lensing of extragalactic galaxies, are not sensitive enough for low string tensions of $G\mu =10^{-10}-10^{-7}$ that are needed to explain this putative signal. We show that strong gravitational lensing of Fast Radio Bursts (FRBs) by cosmic strings is a potentially unambiguous avenue to probe that range of string tension values. The image pair of string lensing are expected to have identical magnification factor and parity, and have a typical time delay of $\sim 10^2(G\mu /10^{-8}{)}^2$ seconds. The unique spectral fingerprint of each FRB, as well as the possibility to detect correlations in the time series of the electric field of the radio waves, will enable verification of the string lensing interpretation. Very-Long-Baseline Interferometry (VLBI) observations can spatially resolve the image pair and provide a lower bound on the string tension based on the image separation. We calculate the FRB lensing rate as a function of FRB detection number for several different models of the FRB redshift distribution. We find that a survey detecting $\sim 10^5$ FRBs, in line with estimates for the detection rate of the forthcoming survey CHORD, can uncover a strong lensing event for a string tension of $G\mu \simeq 10^{-7}$. Larger FRB surveys, such as Phase 2 of the Square Kilometre Array (SKA), have the potential to significantly improve the sensitivity on the string tension to $G\mu \simeq 10^{-9}$.

    ↳ astro-ph.COastro-ph.HEhep-phPRD(2022)·20 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.