Tue·Nov 26, 2019Tuesday·November 26, 2019

1. 01*

   Optical properties of dynamical axion backgrounds

   Jamie I.McDonald🇩🇪 · Luís B. Ventura🇵🇹

   We discuss spectral distortions, time delays and refraction of light in an axion or axion-plasma background. This involves solving the full set of geodesic equations associated to the system of Hamiltonian optics, allowing us to self-consistently take into account the evolution of the momentum, frequency and position of photons. We support our arguments with analytic approximations and full numerical solutions. Remarkably, the introduction of a plasma enhances the sensitivity to axion-induced birefringence, allowing these effects to occur at linear order in the axion-photon coupling even when the axion background is not present at either the emission or detection points. This suggests a general enhancement of axion-induced birefringence when the background refractive index is different from one.

   hep-phastro-ph.COgr-qcPRD(2020)·38 citations
2. 02*

   The Next Higgs Boson(s) and a Higgs-Yukawa Universality

   Christopher T. Hill🇺🇸

   We consider multi-Higgs-doublet models which, for symmetry reasons, have a universal Higgs-Yukawa (HY) coupling, $g$. This is identified with the top quark $g=g_t\approx 1$. The models are concordant with the quasi-infrared fixed point, and the top quark mass is correctly predicted with a compositeness scale (Landau pole) at $M_{planck}$, with sensitivity to heavier Higgs states. The observed Higgs boson is a $\bar{t}t$ composite, and a first sequential Higgs doublet, $H_b$, with $g\approx g_t\approx 1$ coupled to ${\bar{b}}_R(t,b{)}_L$ is predicted at a mass $3.0\lesssim M_b\lesssim 5.5$ TeV and accessible to LHC and its upgrades. This would explain the mass of the $b-$quark, and the tachyonic SM Higgs boson mass${}^2$. The flavor texture problem is no longer associated with the HY couplings, but rather is determined by the inverted multi-Higgs boson mass spectrum, e.g., the lightest fermions are associated with heaviest Higgs bosons and vice versa. The theory is no less technically natural than the standard model. The discovery of $H_b$ at the LHC would confirm the general compositeness idea of Higgs bosons and anticipate additional states potentially accessible to the $100$ TeV $pp$ machine.

   hep-phhep-exhep-th4 citations
3. 03*

   Neutrino mass generation from the perspective of presymmetry

   Ernesto A. Matute🇨🇱

   The Standard Model (SM) with one right-handed neutrino per generation is revisited with presymmetry being the global $U(1{)}_{B-L}$ symmetry of an electroweak theory of leptons and quarks with initially postulated symmetric fractional charges. The cancellation of gauge anomalies and the non-perturbative normalization of lepton charges proceed through the mixing of local and topological charges, the global $B-L$ measuring the induced charge associated with a unit of topological charge, and the mathematical replacement of the original fractional charges with the experimentally observed ones. The $U(1{)}_{B-L}$ symmetry of the SM with Dirac neutrinos is seen as a residual presymmetry. High-scale and low-scale seesaw mechanisms proposed to explain the mass of neutrinos are examined from the perspective of presymmetry, be they of Majorana or pseudo-Dirac type. We find that the tiny mass splitting in pseudo-Dirac neutrinos and the mass of heavy neutrinos ride on the opposite ends of the seesaw. We show that pseudo-Dirac neutrinos contain extra sterile neutrinos with imprints of presymmetry and for heavy ones we get constraints favoring the low-scale linear seesaw over the inverse variant.

   hep-phMod.Phys.Lett.A(2019)·3 citations
4. 04*

   MS4: a BPHZ killer

   N.D. Lenshina🇷🇺 · A.A. Radionov🇷🇺 · F.V. Tkachov🇷🇺

   The UV renormalization scheme ${\text{MS}}^4$ emerged in the formalization of the reasoning which yielded an array of important algorithms in the 80's. ${\text{MS}}^4$ guarantees finiteness of renormalized integrals by construction, satisfies the Stueckelberg-Bogolyubov causality axiom for the R-operation, and turns out to be a 4-dimensional analog of t'Hooft's MS-scheme. The well-known IBP reduction algorithm can be ported to ${\text{MS}}^4$ with modifications, but without problems. ${\text{MS}}^4$ exhibits transparency of the structure, simplicity of the arithmetic at $D=4$, and new calculational options. A straightforward derivation of RG equations runs in terms of explicitly finite quantities and expresses RG functions in terms of explicitly finite integrals.

   hep-phhep-thPhysics of Particles and Nuclei, 2020, Vo…·2 citations
5. 05*

   Pure Natural Quintessential Inflation and Dark Energy

   Selvaganapathy J🇮🇳

   We propose the pure natural quintessential inflation model which is motivated by Witten's conjecture, where the axion couples to pure Yang-Mills $SU(N)$ gauge field at large N limit. This modifies the standard cosine potential which is presented in the natural inflation, making it compatible with current CMB data. Our model gives a successful inflation as well as acceleration at the late times by quintessence inflaton field($\varphi$). Here the inflaton field is responsible for inflation, after that the field enters into peculiar type of reheating and then they act as dynamical dark energy field which follows the same inflation potential and same model parameters. The dynamical field slowly rolls until the Hubble drops to mass of the quintessence field and it reaches the current dark energy field value. Here the dark energy scale is field dependent. Our quintessence model follows thawing frozen approach therefore the frozen quintessence field evolves with respect to cosmic time from initial field value(${\varphi }_i$) to present non-zero minimum field value(${\varphi }_0$). The obtained field value turned into ultra-light and it satisfies the present dark energy density which is $V({\varphi }_0)\approx {\Lambda }_{\text{DE}}^4=(2.3\times 10^{-3}\text{eV}{)}^4$.

   hep-phgr-qchep-thInt.J.Mod.Phys.A(2020)·2 citations
6. 06*

   A Family-nonuniversal $U(1{)}^{\prime }$ Model for Excited Beryllium Decays

   Beyhan Puliçe🇹🇷

   Excited beryllium has been observed to decay into electron-positron pairs with a $6.8\sigma$ anomaly. The process is properly explained by a 17 MeV proto-phobic vector boson. In present work, we consider a family-nonuniversal $U(1{)}^{\prime }$ that is populated by a $U(1{)}^{\prime }$ gauge boson $Z^{\prime }$ and a scalar field $S$, charged under $U(1{)}^{\prime }$ and singlet under the Standard Model (SM) gauge symmetry. The SM chiral fermion and scalar fields are charged under $U(1{)}^{\prime }$ and we provide them to satisfy the anomaly-free conditions. The Cabibbo-Kobayashi-Maskawa (CKM) matrix is reproduced correctly by higher-dimension Yukawa interactions facilitated by $S$. The vector and axial-vector current couplings of the $Z^{\prime }$ boson to the first generation of fermions do satisfy all the bounds from the various experimental data. The $Z^{\prime }$ boson can have kinetic mixing with the hypercharge gauge boson and $S$ can directly couple to the SM-like Higgs field. The kinetic mixing of $Z^{\prime }$ with the hypercharge gauge boson, as we show by a detailed analysis, generates the observed beryllium anomaly. We find that beryllium anomaly can be properly explained by a MeV-scale sector with a minimal new field content. The minimal model we construct forms a framework in which various anomalous SM decays can be discussed.

   hep-phChin.J.Phys.(2021)·22 citations
7. 07*

   SUSY threshold corrections to quark and lepton mixing inspired by $SO(10)$ GUT models

   Yu Muramatsu🇨🇳 · Yoshihiro Shigekami🇨🇳

   In the standard model (SM), the Cabibbo-Kobayashi-Maskawa (CKM) matrix is the only origin of flavor violations (FVs). On the other hand, in general, there are a lot of sources of the FVs in a physics beyond the SM, through the diagonalizing matrices which make Yukawa matrices diagonal. Although most of the diagonalizing matrices are unknown ones, grand unified theories (GUTs) can fix these matrices. In particular, if we consider a GUT model based on the $SO(10)$ group, these diagonalizing matrices are strongly related to each other because of the matter unification. However, this unification causes the problem on the realization of measured SM fermion masses and mixing angles. Up to now, many people showed that supersymmetric (SUSY) threshold corrections can solve this problem, especially unfavorable fermion mass relations. In this paper, we show that how these SUSY threshold corrections affect unknown diagonalizing matrices. Since these contributions are also related to the FVs induced by SUSY particles, we can estimate the maximal effect to the diagonalizing matrices. We found that the $(1,3)$ and $(3,1)$ elements of diagonalizing matrices for quarks can be as large as the corresponding mixing angle of the CKM matrix. Moreover, we found that the higher SUSY scale can predict the larger mixing angles, although strong cancellation between the Higgs mass parameters is needed to realize the electroweak symmetry breaking.

   hep-phJHEP(2020)·1 citation
8. 08*

   The physics of the $\eta$--${\eta }^{\prime }$ system versus $B^0\to J/\Psi \eta ({\eta }^{\prime })$ and $B_s\to J/\Psi \eta ({\eta }^{\prime })$ decays

   M.A. Andreichikov🇷🇺 · M.I. Eides🇺🇸 · V.A. Novikov🇷🇺 · M.I. Vysotsky🇷🇺

   An approach to the properties of the $\eta$--${\eta }^{\prime }$ system developed to solve the famous $U(1)$ problem is used to calculate the partial widths ratios to $\eta$ and ${\eta }^{\prime }$ in the $B^0\to J/\Psi \eta ({\eta }^{\prime },{\pi }^0)$ and $B_s\to J/\Psi \eta ({\eta }^{\prime })$ decays. We obtain the results in agreement with the experimental data.

   hep-phhep-exInt.J.Mod.Phys.A(2020)·1 citation
9. 09*

   Analysis of an $SU(8)$ model with a spin-$\frac{1}{2}$ field directly coupled to a gauged Rarita-Schwinger spin-$\frac{3}{2}$ field

   Stephen L. Adler🇺🇸

   In earlier work we analyzed an abelianized model in which a gauged Rarita-Schwinger spin-$\frac{3}{2}$ field is directly coupled to a spin-$\frac{1}{2}$ field. Here we extend this analysis to the gauged $SU(8)$ model for which the abelianized model was a simplified substitute. We calculate the gauge anomaly, show that anomaly cancellation requires adding an additional left chiral representation $\overline{8}$ spin-$\frac{1}{2}$ fermion to the original fermion complement of the $SU(8)$ model, and give options for restoring boson-fermion balance. We conclude with a summary of attractive features of the reformulated $SU(8)$ model, including a possible connection to the $E_8$ root lattice.

   hep-phInt.J.Mod.Phys.A(2019)·3 citations
10. 10*

    Scale-invariant scalar field dark matter through the Higgs portal

    Catarina Cosme🇨🇦

    We introduce an oscillating scalar field coupled to the Higgs that can account for all dark matter in the Universe. Due to an underlying scale invariance of this model, the dark scalar only acquires mass after the electroweak phase transition. We discuss the dynamics of this dark matter candidate, showing that it behaves like dark radiation until the Electroweak phase transition and like non-relativistic matter afterwards. In the case of a negative coupling to the Higgs field, the scalar gets a vacuum expectation value after the electroweak phase transition and may decay into photons, although being sufficiently long-lived to account for dark matter. We show that, within this scenario, for a mass of 7 keV, the model can explain the observed galactic and extra-galactic 3.5 keV X-ray line. Nevertheless, it will be very difficult to probe this model in the laboratory in the near future.

    hep-phastro-ph.CO0 citations
11. 11*

    Mixed scalar-pseudoscalar Higgs boson production through next-to-next-to-leading order at the LHC

    Matthieu Jaquier🇩🇪 · Raoul Röntsch🇨🇭

    We study the production of a mixed scalar-pseudoscalar Higgs boson in gluon fusion at the LHC, through next-to-next-to-leading order (NNLO) in QCD. We obtain fully differential results, including the decay of the Higgs boson to two charged lepton pairs. We discuss the impact of the interference between the scalar and pseudoscalar states. We also show differential distributions for several kinematic variables whose shape is sensitive to the parity of the Higgs boson, and assess the impact of the NNLO QCD corrections on these shapes.

    hep-phJHEP(2020)·8 citations
12. 12*

    Neutrino Phenomenology from Democratic Approach

    Itishree Sethi🇮🇳 · Biswaranjan Behera🇺🇸 · Mitesh Kumar Behera🇮🇳

    In this article, we derive the tiny neutrino masses and mixings from the democratic and diagonal texture approach, which consistent with the recent experimental oscillation data. The unitary rotation matrices, which diagonalize the neutrino mass matrices are obtained by a specific parametrization of the Pontecorvo-Maki-Nakagawa-Sakata (PMNS) mixing matrix. From which, we tried to calculate all three mixing angles as well as the Dirac CP-violating phase interms of model mixing parameters. In particular, the deviation from the tribimaximal mixing is explained in this model. Along with the Jarlskog parameter in terms of model parameter and neutrino-less double beta decay (NDBD) has been discussed briefly.

    hep-ph0 citations
13. 13*

    Analysis of the semileptonic and nonleptonic two-body decays of the double heavy charm baryon states ${\Xi }_{cc}^{++},{\Xi }_{cc}^{+}$ and ${\Omega }_{cc}^{+}$

    Thomas Gutsche🇩🇪 · Mikhail A. Ivanov🇷🇺 · Jürgen G. Körner🇩🇪 · Valery E. Lyubovitskij🇩🇪 · Zhomart Tyulemissov🇷🇺

    We calculate the semileptonic and a subclass of sixteen nonleptonic two-body decays of the double charm baryon ground states ${\Xi }_{cc}^{++},{\Xi }_{cc}^{+}$ and ${\Omega }_{cc}^{+}$ where we concentrate on the nonleptonic decay modes. We identify those nonleptonic decay channels in which the decay proceeds solely via the factorizing contribution precluding a contamination from $W$-exchange. We use the covariant confined quark model previously developed by us to calculate the various helicity amplitudes which describe the dynamics of the $1/2^{+}\to 1/2^{+}$ and $1/2^{+}\to 3/2^{+}$ transitions induced by the Cabibbo favored effective $(c\to s)$ and $(d\to u)$ currents. We then proceed to calculate the rates of the decays as well as polarization effects and angular decay distributions of the prominent decay chains resulting from the nonleptonic decays of the double heavy charm baryon parent states.

    hep-phPRD(2019)·44 citations
14. 14*

    Nuclear EDM from SMEFT flavor-changing operator

    Motoi Endo🇯🇵 · Daiki Ueda🇯🇵

    We study nuclear electric dipole moments induced by $\Delta F=1$ effective operators in the Standard Model Effective Field Theory. Such contributions arise through renormalization group evolutions and matching conditions at the electroweak symmetry breaking scale. We provide one-loop formulae for the matching conditions. We also discuss correlations of these effects with $\Delta F=2$ observables such as ${ϵ}_K$ and $\Delta M_{B_d}$.

    hep-phhep-exJHEP(2020)·4 citations
15. 15*

    Interactions between two heavy mesons within heavy meson chiral effective field theory

    Zhan-Wei Liu🇨🇳 · Bo Wang🇨🇳 · Hao Xu🇨🇳 · Ning Li🇺🇸 · Xiang Liu🇨🇳 · Shi-Lin Zhu🇨🇳

    We have studied the interactions between two heavy mesons ($D^{(\ast )}$-$D^{(\ast )}$, ${\bar{D}}^{(\ast )}$-${\bar{D}}^{(\ast )}$, $B^{(\ast )}$-$B^{(\ast )}$, or ${\bar{B}}^{(\ast )}$-${\bar{B}}^{(\ast )}$) within heavy meson chiral effective field theory and investigated possible molecular states. The effective potentials are obtained with Weinberg's scheme up to one-loop level. At the leading order, four body contact interactions and one pion exchange contributions are considered. In addition to two pion exchange diagrams, we include the one-loop chiral corrections to contact terms and one pion exchange diagrams at the next-to-leading order. The effective potentials both in momentum space and coordinate space are investigated and discussed extensively. The possible molecular states are also studied and the binding energies are provided by solving the Schrodinger equation. The results will be helpful for the experimental search for the doubly-heavy molecular states.

    hep-ph1 citation
16. 16*

    True muonium production in ultraperipheral $PbPb$ collisions

    C. Azevedo🇧🇷 · V.P. Goncalves🇧🇷 · B.D. Moreira🇧🇷

    In this paper we investigate the production of a true muonium state, which is an atom consisting of a ${\mu }^{+}{\mu }^{-}$ bound state, by $\gamma \gamma$ interactions in ultraperipheral $PbPb$ collisions considering an accurate treatment of the absorptive corrections and for the nuclear form factor. The rapidity distributions and cross sections are estimated considering the RHIC, LHC and FCC energies. Our results indicate that the experimental analysis can be useful to observe, for the first time, the true muonium state.

    hep-phhep-exnucl-thPRC(2020)·24 citations
17. 17*

    Photoproduction of pentaquarks states at the LHC

    V. P. Goncalves🇧🇷 · M. M. Jaime🇨🇴

    In this paper we investigate the production of pentaquark states in the photon -- proton interactions present in hadronic collisions at the RHIC and LHC. We consider two phenomenological models for the $J/\Psi$ photoproduction that consider the presence of the $P_c(4312)$, $P_c(4440)$ and $P_c(4457)$ resonances in the $s$ -- channel of the $\gamma p\to J/\Psi p$ reaction. The rapidity distribution is estimated for $pA$ collisions at the RHIC and LHC. Predictions for $pPb$, $PbAr$ and $PbHe$ fixed -- target collisions at the LHC are also presented. We demonstrate that the experimental analysis of the $J/\Psi$ photoproduction in fixed -- target collisions can provide complementary and independent checks on these states, and help to understand their underlying nature.

    hep-phhep-exPLB(2020)·18 citations
18. 18*

    Proton structure from a light-front Hamiltonian

    Chandan Mondal. Siqi Xu · Jiangshan Lan · Xingbo Zhao · Yang Li · Dipankar Chakrabarti · James P. Vary

    We obtain the electromagnetic form factors, the axial form factor, and the parton distribution functions of the proton from the eigenstates of a light-front effective Hamiltonian in the leading Fock representation suitable for low-momentum scale applications. The electromagnetic and the axial form factors are found to be in agreement with the available experimental data. The unpolarized, the helicity, and the transversity valence quark distributions, after QCD evolution, are consistent with the global QCD analyses. The tensor charge also agree the experimental data, while the axial charge is somewhat outside the experimental error bar.

    hep-phnucl-thPRD(2020)·97 citations
19. 19*

    Doubly Heavy Tetraquarks in QCD Sum Rules

    Liang Tang🇨🇳 · Bin-Dong Wan🇨🇳 · Kim Maltman🇨🇦 · Cong-Feng Qiao🇨🇳

    In the framework of QCD Sum Rules we investigate the $q{q}^{\prime }\bar{Q}\bar{Q}$ tetraquark structure with quantum number $J^P=1^{+}$, which are embedded in two types of configurations, the $[8_c{]}_{q\bar{Q}}\otimes [8_c{]}_{q^{\prime }\bar{Q}}$ and $[1_c{]}_{q\bar{Q}}\otimes [1_c{]}_{q^{\prime }\bar{Q}}$ with $Q=b,c$, $q=u$, and $q^{\prime }=d,s$. Our finding confirms the Lattice QCD result that the bottom tetraquark states could exist and their masses are evaluated. In the calculation, the non-perturbative condensate contributions up to dimension eight in operator product expansion are considered, and those terms linear to the strange quark mass $m_s$ are kept. It is found that for octet-octet configuration the masses of potential tetraquark states are about $11.28$ GeV for the $ud\bar{b}\bar{b}$ system, and $11.31$ and $11.34$ GeV for the $us\bar{b}\bar{b}$ system, which are above the corresponding two-meson thresholds. For molecular configuration, the corresponding masses are found below the thresholds, that is $10.36$ GeV and $10.48$ GeV, respectively. The possible tetraquark decay channels are analyzed and the strong decay rates are evaluated. The mass dependence on the radiative correction and the condensates is estimated. Moreover, the doubly charmed tetraquark states are also considered.

    hep-phPRD(2020)·80 citations
20. 20*

    Light sterile neutrinos and their implications on currently running long-baseline and neutrinoless double beta decay experiments

    Rudra Majhi🇮🇳 · Soumya C🇮🇳 · Rukmani Mohanta🇮🇳

    Recent ${\nu }_e$ appearance data from the Mini Booster Neutrino Experiment (MiniBooNE) are in support of the excess of events reported by the Liquid Scintillator Neutrino Detector (LSND), which provides an indirect hint for the existence of eV-scale sterile neutrino. As these sterile neutrinos can mix with the standard active neutrinos, in this paper we explore the effect of such active-sterile mixing on the determination of various oscillation parameters by the currently running long-baseline neutrino experiments T2K and NO$\nu$A. We find that the existence of sterile neutrino can lead to new kind of degeneracies among these parameters which would substantially deteriorate the mass hierarchy sensitivity of NO$\nu$A experiment. We further notice that the inclusion of data from T2K experiment helps in resolving the degeneracies. The impact of new CP violating phases ${\delta }_{14}$ and ${\delta }_{34}$ on the maximal CP-violation exclusion sensitivity for NO$\nu$A experiment has also been illustrated. Finally, we discuss the implication of such light sterile neutrinos on neutrinoless double beta decay processes in line with recent experimental results, as well as on the sensitivity reach of future experiments.

    hep-phJ.Phys.G(2020)·11 citations
21. 21*

    Two photon exchange in elastic electron scattering off hadronic systems

    Dmitry Borisyuk🇺🇦 · Alexander Kobushkin🇺🇦

    In the present review we discuss different aspects of the two-photon exchange (TPE) physics in elastic $ep$ scattering, at high $Q^2$ as well as at low $Q^2$. The imaginary part of the TPE amplitude gives rise to beam and target single-spin asymmetries. Different theoretical approaches to calculation of these observables are considered. The real part of the TPE amplitude influence unpolarized cross section and double-spin observables and is, most likely, responsible for discrepancy between two methods of proton form factors measurements. We review different methods of calculations of the TPE amplitudes the framework of "hadron" and "quark-gluon" approaches. We discuss the dispersion approach suitable for low and intermediate $Q^2$, which includes elastic and inelastic intermediate hadronic states, as well as connection of TPE to proton radius puzzle. The present situation with direct experimental searches for the TPE amplitude in $e^{+}p/e^{-}p$ charge asymmetry is also discussed, as well as attempts to extract the TPE amplitudes from existing experimental data obtained by the Rosenbluth and double polarization techniques. The TPE physics in other processes, such as elastic $\mu p$, $e$-nucleus and $e\pi$ scattering is also reviewed.

    hep-phUkr.Phys.J.(2021)·10 citations
22. 22*

    Spectrum of strange singly charmed baryons in the constituent quark model

    Keval Gandhi🇮🇳 · Ajay Kumar Rai🇮🇳

    Excited states masses of the strange singly charmed baryons are calculated using the non-relativistic approach of hypercentral Constituent Quark Model (hCQM). The hyper-Coulomb plus screened potential is used as a confinement potential with the first order correction. The spin-spin, spin-orbit and spin-tensor interaction terms are included perturbatively. Our calculated masses are allowed to construct the Regge trajectories in both $(n_r,M^2)$ and $(J,M^2)$ planes. The mass spectra and the Regge trajectories study predict the spin-parity of $\Xi {}_c(2970{)}^{+/0}$, $\Xi {}_c(3080{)}^{+/0}$, $\Xi {}_c(3123{)}^{+}$, $\Omega {}_c(3000{)}^0$ and $\Omega {}_c(3119{)}^0$ baryons. Moreover, the strong one pion decay rates of the isodoublet states of $\Xi {}_c(2645)$, $\Xi {}_c(2790)$ and $\Xi {}_c(2815)$ are analyzed in the framework of Heavy Hadron Chiral Perturbation Theory (HHChPT). Also, the ground state magnetic moments and the radiative decay rates based on the transition magnetic moments are calculated in the framework of constituent quark model.

    hep-phEur.Phys.J.Plus(2020)·38 citations
23. 23*

    Feynman Rules in terms of the Wigner transformed Green functions

    C.X. Zhang🇮🇱 · M.A. Zubkov🇮🇱

    In the models defined on the inhomogeneous background the propagators depend on the two space - time momenta rather than on one momentum as in the homogeneous systems. Therefore, the conventional Feynman diagrams contain extra integrations over momenta, which complicate calculations. We propose to express all amplitudes through the Wigner transformed propagators. This approach allows us to reduce the number of integrations. As a price for this the ordinary products of functions are replaced by the Moyal products. The corresponding rules of the diagram technique are formulated using an example of the model with the fermions interacting via an exchange by scalar bosons. The extension of these rules to the other models is straightforward. This approach may simplify calculations in certain particular cases. The most evident one is the calculation of various non - dissipative currents.

    hep-phPLB(2020)·11 citations
24. 24*

    Complete Vector-like Fourth Family with ${\mathrm{U}(1)}^{\prime }$: A Global Analysis

    Junichiro Kawamura🇺🇸 · Stuart Raby🇺🇸 · Andreas Trautner🇩🇪

    In this paper we present an in-depth analysis of a recently proposed Standard Model extension with a complete fourth generation of quarks and leptons, which are vector-like with respect to the Standard Model gauge group and charged under a new spontaneously broken vector-like $\mathrm{U}(1{)}^{\prime }$ gauge symmetry. The model is designed to explain the known muon anomalies, i.e. the observed deviations from Standard Model predictions in the anomalous magnetic moment of the muon, $\Delta a_{\mu }$, and in $b\to s{\ell }^{+}{\ell }^{-}$ processes. We perform a global ${\chi }^2$ analysis of the data with $65$ model parameters and including $98$ observables. We find many points with ${\chi }^2$ per degree of freedom $\le 1$. The vector-like leptons and the new heavy $Z^{\prime }$ are typically much lighter than a TeV and would, thus, be eminently visible at the HL-LHC.

    hep-phhep-exPRD(2020)·37 citations
25. 25*

    Astrophysical probes of inelastic dark matter with a light mediator

    Gerardo Alvarez🇺🇸 · Hai-Bo Yu🇺🇸

    We consider an inelastic dark matter model, where a fermion is charged under a broken U(1) gauge symmetry, and introduce a tiny Majorana mass term to split the fermion into two states with the light one being a dark matter candidate. If the gauge boson is light, it can mediate both elastic and inelastic dark matter self-interactions in dark halos, leading to observational consequences. Using a numerical technique based on partial wave analysis, we accurately calculate the elastic and inelastic self-scattering cross sections. We assume a thermal freeze-out scenario and fix the gauge coupling constant using the relic density constraint. Then, we focus on six benchmark masses of dark matter, covering a wide range from $10\mathrm{MeV}$ to $160\mathrm{GeV}$ and map parameter regions where the elastic scattering cross section per unit mass is within $1\mathrm{c}{\mathrm{m}}^2/g-5\mathrm{c}{\mathrm{m}}^2/g$, favored to solve small-scale issues of cold dark matter. If the heavy state can decay to the light state and a massless species, the inelastic up-scattering process can cool the halo and lead to core collapse. Taking galaxies with evidence of dark matter density cores, we further derive constraints on the parameter space. For dark matter masses below $10\mathrm{GeV}$, the mass splitting must be large enough to forbid up scattering in the dwarf halo for evading the core-collapse constraint; while for higher masses, the up-scattering process can still be allowed. Our results show astrophysical observations can provide powerful tests for dark matter models with large elastic and inelastic self-interactions.

    hep-phPRD(2020)·32 citations
26. 26*

    A new way of calculating the effective potential for a light radion

    J. M. Lizana🇵🇱 · M. Olechowski🇵🇱 · S. Pokorski🇵🇱

    We address again the old problem of calculating the radion effective potential in Randall-Sundrum scenarios, with the Goldberger-Wise stabilization mechanism. Various prescriptions have been used in the literature, most of them based on heuristic derivations and then applied in some approximations. We define rigorously a light radion 4D effective action by using the interpolating field method. For a given choice of the interpolating field, defined as a functional of 5D fields, the radion effective action is uniquely defined by the procedure of integrating out the other fields, with the constrained 5D equations of motion always satisfied with help of the Lagrange multipliers. Thus, for a given choice of the interpolating fields we obtain a precise prescription for calculating the effective potential. Different choices of the interpolating fields give different prescriptions but in most cases very similar effective potentials. We confirm the correctness of one prescription used so far on a more heuristic basis and also find several new, much more economical, ways of calculating the radion effective potential. Our general considerations are illustrated by several numerical examples. It is shown that in some cases the old methods, especially in models with strong back-reaction, give results which are off even by orders of magnitude. Thus, our results are important e.g. for estimation of critical temperature in phase transitions.

    hep-phhep-thJHEP(2020)·4 citations
27. 27*

    On the interplay between the loop-tree duality and helicity amplitudes

    Felix Driencourt-Mangin🇪🇸 · German Rodrigo🇪🇸 · German F. R. Sborlini🇪🇸 · William J. Torres Bobadilla🇪🇸

    The spinor-helicity formalism has proven to be very efficient in the calculation of scattering amplitudes in quantum field theory, while the loop tree duality (LTD) representation of multi-loop integrals exhibits appealing and interesting advantages with respect to other approaches. In view of the most recent developments in LTD, we exploit the synergies with the spinor-helicity formalism to analyse illustrative one- and two-loop scattering processes. We focus our discussion on the local UV renormalisation of IR and UV finite amplitudes and present a fully automated numerical implementation that provides efficient expressions which are integrable directly in four space-time dimensions.

    hep-phhep-thPRD(2022)·41 citations
28. 28*

    Hadronic Footprint of GeV-Mass Dark Matter

    Tilman Plehn🇩🇪 · Peter Reimitz🇩🇪 · Peter Richardson🇨🇭

    GeV-scale dark matter is an increasingly attractive target for direct detection, indirect detection, and collider searches. Its annihilation into hadronic final states produces a challenging zoo of light hadronic resonances. We update Herwig7 to study the photon and positron spectra from annihilation through a vector mediator. It covers dark matter masses between 250 MeV and 5 GeV and includes an error estimate.

    hep-phSciPost Phys.(2020)·30 citations
29. 29*

    The three-loop polarized pure singlet operator matrix element with two different masses

    J. Ablinger🇦🇹 · J. Blümlein🇩🇪 · A. De Freitas🇩🇪 · M. Saragnese🇩🇪 · C. Schneider🇦🇹 · K. Schönwald🇩🇪

    We present the two-mass QCD contributions to the polarized pure singlet operator matrix element at three loop order in $x$-space. These terms are relevant for calculating the polarized structure function $g_1(x,Q^2)$ at $O({\alpha }_s^3)$ as well as for the matching relations in the variable flavor number scheme and the polarized heavy quark distribution functions at the same order. The result for the operator matrix element is given in terms of generalized iterated integrals. These integrals depend on the mass ratio through the main argument, and the alphabet includes square--root valued letters.

    hep-phhep-thNPB(2020)·29 citations
30. 30*

    The study of the gluon distribution function and reduced cross section behavior using the proton structure function

    B.Rezaei · G.R.Boroun

    The behavior of the gluon distribution function and the reduced cross section considered from the proton structure function and its derivatives at low values of $x$. These behaviors studied and compared with the experimental data. These results are augmented by including an additional higher-twist term in the description of the nonlinear correction. This additional term, modified nonlinear correction, improves the description of the reduced cross sections significantly at low values of $Q^2$. We discuss, furthermore, how this behavior can be determine the reduced cross section with respect to the proton parameterization at high-y values. The resulting predictions for ${\sigma }_r$ suggest that further corrections are required for $Q^2$ less than about $3{\mathrm{GeV}}^2$.

    hep-phNPA(2021)·6 citations
31. 31*

    The Color Dipole Picture and extracting the ratio of structure functions at small $x$

    B. Rezaei🇮🇷 · G.R. Boroun🇮🇷

    We present a set of formulas to extract the ratio $F_L(x,Q^2)/F_2(x,Q^2)$ and $R(x,Q^2)$ from the proton structure function parameterized in the next-to-next-to-leading order of the perturbative theory at low $x$ values. The behavior of these ratios are considered with respect to the power-law behavior of the proton structure function. The results are compared with experimental data and the color dipole model bounds. These ratios are in good agreement with the HERA data throughout the fixed value of the invariant mass. The behavior of these ratios controlled by the nonlinear corrections at low values of $Q^2$. These results and comparison with HERA data demonstrate that the suggested method for the ratio of structure functions can be applied in analyses of the LHeC and FCC-eh projects.

    hep-phPRC(2020)·13 citations
32. 32*

    Infrared and transcendental structure of two-loop supersymmetric QCD amplitudes

    Gregor Kälin🇸🇪 · Gustav Mogull🇸🇪 · Alexander Ochirov🇨🇭 · Bram Verbeek🇸🇪

    Using a careful choice of infrared (IR) subtraction scheme, we demonstrate the cancellation of all terms with transcendental weights 0,1,2 from the finite part of the full-color two-loop four-gluon $\mathcal{N}=2$ supersymmetric QCD amplitude, with $N_f$ massless supersymmetric quarks. This generalizes the previously observed cancellation of weight-2 terms in the superconformal theory, where $N_f=2N_c$ for gauge group SU$(N_c)$. The subtraction scheme follows naturally both from general IR factorization principles and from an integrand-level analysis of divergences in this amplitude. The divergences are written in terms of scalar triangle integrals whose expressions are known to all orders in the dimensional regulator $ϵ=(4-D)/2$. We also present integrated expressions for the full-color two-loop four-point amplitudes with both matter and vectors on external legs in which lower-weight terms also cancel using an appropriate IR scheme. This provides us with values for the two-loop cusp, gluonic, and quark anomalous dimensions in $\mathcal{N}=2$ supersymmetric QCD, which are cross-checked between the three different amplitudes.

    ↳ hep-thhep-phJHEP(2020)·6 citations
33. 33*

    Searching for new physics with profile likelihoods: Wilks and beyond

    Sara Algeri🇺🇸 · Jelle Aalbers🇸🇪 · Knut Dundas Morå🇸🇪 · Jan Conrad🇸🇪

    Particle physics experiments use likelihood ratio tests extensively to compare hypotheses and to construct confidence intervals. Often, the null distribution of the likelihood ratio test statistic is approximated by a ${\chi }^2$ distribution, following a theorem due to Wilks. However, many circumstances relevant to modern experiments can cause this theorem to fail. In this paper, we review how to identify these situations and construct valid inference.

    ↳ physics.data-anastro-ph.HEhep-exhep-ph+1Nature Rev.Phys.(2020)·102 citations
34. 34*

    Initial state fluctuations of QCD conserved charges in heavy-ion collisions

    Mauricio Martinez🇺🇸 · Matthew D. Sievert🇺🇸 · Douglas E. Wertepny🇮🇱 · Jacquelyn Noronha-Hostler🇺🇸

    We initialize the Quantum Chromodynamic conserved charges of baryon number, strangeness, and electric charge arising from gluon splitting into quark-antiquark pairs for the initial conditions of relativistic heavy-ion collisions. A new Monte Carlo procedure that can sample from a generic energy density profile is presented, called Initial Conserved Charges in Nuclear Geometry (ICCING), based on quark and gluon multiplicities derived within the color glass condensate (CGC) effective theory. We find that while baryon number and electric charge have nearly identical geometries to the energy density profile, the initial strangeness distribution is considerable more eccentric and is produced primarily at the hot spots corresponding to temperatures of $T\gtrsim 400$ MeV for PbPb collisions at $\sqrt{s_{NN}}=5.02$ TeV.

    ↳ nucl-thhep-ph35 citations
35. 35*

    Gravitational waves from the quasi-circular inspiral of compact binaries in Einstein-aether theory

    Chao Zhang🇺🇸 · Xiang Zhao🇺🇸 · Anzhong Wang🇺🇸 · Bin Wang🇨🇳 · Kent Yagi🇺🇸 · Nicolas Yunes🇺🇸 · Wen Zhao🇨🇳 · Tao Zhu🇨🇳

    We study gravitational waves emitted by a binary system of non-spinning bodies in a quasi-circular inspiral within the framework of Einstein-aether theory. In particular, we compute explicitly and analytically the expressions for the time-domain and frequency-domain waveforms, gravitational wave polarizations, and response functions for both ground- and space-based detectors in the post-Newtonian approximation. We find that, when going beyond leading-order in the post-Newtonian approximation, the non-Einsteinian polarization modes contain terms that depend on both the first and the second harmonics of the orbital phase. We also calculate analytically the corresponding parameterized post-Einsteinian parameters, generalizing the existing framework to allow for different propagation speeds among scalar, vector and tensor modes, without assumptions about the magnitude of its coupling parameters, and meanwhile allowing the binary system to have relative motions with respect to the aether field. Such results allow for the easy construction of Einstein-aether templates that could be used in Bayesian tests of General Relativity in the future.

    ↳ gr-qchep-phhep-thPRD(2020)·69 citations
36. 36*

    Fakeons, quantum gravity and the correspondence principle

    Damiano Anselmi🇮🇹

    The correspondence principle made of unitarity, locality and renormalizability has been very successful in quantum field theory. Among the other things, it helped us build the standard model. However, it also showed important limitations. For example, it failed to restrict the gauge group and the matter sector in a powerful way. After discussing its effectiveness, we upgrade it to make room for quantum gravity. The unitarity assumption is better understood, since it allows for the presence of physical particles as well as fake particles (fakeons). The locality assumption is applied to an interim classical action, since the true classical action is nonlocal and emerges from the quantization and a later process of classicization. The renormalizability assumption is refined to single out the special role of the gauge couplings. We show that the upgraded principle leads to an essentially unique theory of quantum gravity. In particular, in four dimensions, a fakeon of spin 2, together with a scalar field, is able to make the theory renormalizable while preserving unitarity. We offer an overview of quantum field theories of particles and fakeons in various dimensions, with and without gravity.

    ↳ hep-thgr-qchep-phphysics.hist-ph6 citations
37. 37*

    Inflationary magnetogenesis with helical coupling

    Yu. V. Shtanov🇺🇦 · M. V. Pavliuk🇺🇦

    We describe a simple scenario of inflationary magnetogenesis based on a helical coupling to electromagnetism. It allows to generate helical magnetic fields of strength of order up to $10^{-7}\text{G}$, when extrapolated to the current epoch, in a narrow spectral band centered at any physical wavenumber by adjusting the model parameters. Additional constraints on magnetic fields arise from the considerations of baryogenesis and, possibly, from the Schwinger effect of creation of charged particle-antiparticle pairs.

    ↳ astro-ph.COgr-qchep-phUkr.Phys.J.(2019)·18 citations
38. 38*

    Is Trans-Planckian Censorship a Swampland Conjecture?

    Ryo Saito🇯🇵 · Satoshi Shirai🇯🇵 · Masahito Yamazaki🇯🇵

    During an accelerated expansion of the Universe, quantum fluctuations of sub-Planckian size can be stretched outside the horizon and be regarded effectively classical. Recently, it has been conjectured that such horizon-crossing of trans-Planckian modes never happens inside theories of quantum gravity (the trans-Planckian censorship conjecture, TCC). We point out several conceptual problems of this conjecture, which is in itself formulated as a statement on the restriction of possible scenarios in a theory: by contrast a standard swampland conjecture is a restriction of possible theories in the landscape of the quantum gravity. We emphasize the concept of swampland universality, i.e. that a swampland conjecture constrains any possible scenario in a given effective field theory. In order to illustrate the problems clearly we introduce several versions of the conjecture, where TCC condition is imposed differently to scenarios realizable in a given theory. We point out that these different versions of the conjecture lead to observable differences: a TCC violation in another Universe can exclude a theory, and such reduction of the landscape restricts possible predictions in our Universe. Our analysis raises the question of whether or not the trans-Planckian censorship conjecture can be regarded as a swampland conjecture concerning the existence of UV completion.

    ↳ hep-thastro-ph.COgr-qchep-phPRD(2020)·19 citations
39. 39*

    The running curvaton

    Lei-Hua Liu🇨🇳 · Wu-Long Xu🇨🇳

    Inspired by \cite{Jiang:2018uce}, we propose a similar curvaton mechanism whose realization occurs in preheating process, in which the effective mass is running (its potential consists of coupling part and exponential part whose contribution is subdominant comparing to the coupling part). The production of curvaton contains the cases of narrow resonance and broad resonances whose criteria comes via the spectral index of curvaton. Since the inflationary potential is chaotic inflation (quadratic potential), it could smoothly transit into the preheating process. Once the entropy perturbation transferred into curvature perturbation, we will use $\delta N$ formalism to investigate its validity. By neglecting the contribution of exponential potential of curvaton, we calculate power spectrum $P_{\zeta }$ and non linear Non-Gaussian parameter $f_{NL}$. Our calculation analytically shows that these two observables are independent of potential of inflaton. Finally, as the curvaton almost decay (inflaton field vanishes), the exponential potential will be approaching a constant of order of cosmological constant, which may play a role of dark energy.

    ↳ astro-ph.COgr-qchep-phhep-thCPC(2020)·15 citations
40. 40*

    Tension of the $E_G$ statistic and RSD data with Planck/$\Lambda$CDM and implications for weakening gravity

    F. Skara🇬🇷 · L. Perivolaropoulos🇬🇷

    The $E_G$ statistic is a powerful probe for detecting deviations from GR by combining weak lensing (WL), real-space clustering and redshift space distortion (RSD) measurements thus probing both the lensing and the growth effective Newton constants ($G_L$ and $G_{eff}$). We construct an up to date compilation of $E_G$ statistic data including both redshift and scale dependence ($E_G(R,z)$). We combine this $E_G$ data compilation with an up to date compilation of $f{\sigma }_8$ data from RSD observations to identify the current level of tension between the Planck/$\Lambda$CDM standard model based on general relativity and a general model independent redshift evolution parametrization of $G_L$ and $G_{eff}$. Each $f{\sigma }_8$ datapoint considered has been published separately in the context of independent analyses of distinct galaxy samples. However, there are correlations among the datapoints considered due to overlap of the analyzed galaxy samples. Due to these correlations the derived levels of tension of the best fit parameters with Planck/$\Lambda$CDM are somewhat overestimated but this is the price to pay for maximizing the information encoded in the compilation considered. We find that the level of tension increases from about $3.5\sigma$ for the $f{\sigma }_8$ data compilation alone to about $6\sigma$ when the $E_G$ data are also included in the analysis. The direction of the tension is the same as implied by the $f{\sigma }_8$ RSD growth data alone (lower ${\Omega }_m$ and/or weaker effective Newton constant at low redshifts for both the lensing and the growth effective Newton constants ($G_L$ and $G_{eff}$)). These results further amplify the hints for weakening modified gravity discussed in other recent analyses.

    ↳ astro-ph.COgr-qchep-phhep-thPRD(2020)·89 citations
41. 41*

    Astrophysical and local constraints on string theory: runaway dilaton models

    C. J. A. P. Martins🇵🇹 · L. Vacher🇫🇷

    One of the clear predictions of string theory is the presence of a dynamical scalar partner of the spin-2 graviton, known as the dilaton. This will violate the Einstein Equivalence Principle, leading to a plethora of possibly observable consequences which is a cosmological context include dynamical dark energy and spacetime variations of nature's fundamental constants. The runaway dilaton scenario of Damour, Piazza and Veneziano is a particularly interesting class of string theory inspired models which can in principle reconcile a massless dilaton with experimental data. Here we use the latest background cosmology observations, astrophysical and laboratory tests of the stability of the fine-structure constant and local tests of the Weak Equivalence Principle to provide updated constraints on this scenario, under various simplifying assumptions. Overall we find consistency with the standard $\Lambda$CDM paradigm, and we improve the existing constraints on the coupling of the dilaton to baryonic matter by a factor of six, and to the dark sector by a factor of two. At the one sigma level the current data already excludes dark sector couplings of order unity, which would be their natural value.

    ↳ astro-ph.COgr-qchep-phhep-thPRD(2019)·15 citations
42. 42*

    Towards a composite Higgs and a partially composite top quark

    B. Svetitsky🇮🇱 · V. Ayyar🇺🇸 · T. DeGrand🇺🇸 · M. Golterman🇺🇸 · D. C. Hackett🇺🇸 · W. I. Jay🇺🇸 · E. T. Neil🇺🇸 · Y. Shamir🇮🇱

    We have calculated quantities of interest to a theory of compositeness. The lattice model, approximating the candidate theory, is the SU(4) gauge theory coupled to fermions in two color representations. For the composite Higgs, a current correlator gives one of the ingredients of the effective Higgs potential. For the partially composite top quark, we have hyperbaryon matrix elements that govern mixing of the fundamental quark with its heavy composite partner. The matrix elements turn out to be so small that the theory is disfavored as a source of a realistic top mass.

    ↳ hep-lathep-phPoS(2019)·3 citations
43. 43*

    Equilibration and baryon densities attainable in relativistic heavy-ion collisions

    Yu. B. Ivanov🇷🇺 · A. A. Soldatov🇷🇺

    Kinetic equilibration of the matter and baryon densities attained in central region of colliding Au+Au nuclei in the energy range of $\sqrt{s_{NN}}=$ 3.3--39 GeV are examined within the model of the three-fluid dynamics. It is found that the kinetic equilibration is faster at higher collision energies: the equilibration time (in the c.m. frame of colliding nuclei) rises from $\sim$5 fm/c at $\sqrt{s_{NN}}=$ 3.3 GeV to $\sim$1 fm/c at 39 GeV. The chemical equilibration, and thus thermalization, takes longer. We argue that the presented time evolution of the net-baryon and energy densities in the central region is a necessary prerequisite of proper reproduction of bulk observables in midrapidity. We suggest that for informative comparison of predictions of different models it is useful to calculate an invariant 4-volume ($V_4$), where the proper density the equilibrated matter exceeds certain value. The advantage of this 4-volume is that it does not depend on specific choice of the 3-volume in different studies and takes into account the lifetime of the high-density region, which also matters. The 4-volume $V_4=$ 100 fm${}^4$/c is chosen to compare the baryon densities attainable at different different energies. It is found that the highest proper baryon density increases with the collision energy rise, from $n_B/n_0\approx$ 4 at 3.3 GeV to $n_B/n_0\approx$ 30 at 39 GeV. These highest densities are achieved in the central region of colliding system.

    ↳ nucl-thhep-phPRC(2020)·8 citations
44. 44*

    Probing the Small-Scale Matter Power Spectrum with Large-Scale 21-cm Data

    Julian B. Muñoz🇺🇸 · Cora Dvorkin🇺🇸 · Francis-Yan Cyr-Racine🇺🇸

    The distribution of matter fluctuations in our universe is key for understanding the nature of dark matter and the physics of the early cosmos. Different observables have been able to map this distribution at large scales, corresponding to wavenumbers $k\lesssim 10$ Mpc${}^{-1}$, but smaller scales remain much less constrained. The 21-cm line is a promising tracer of early stellar formation, which took place in small haloes (with masses $M\sim 10^6-10^8{M}_{\odot }$), formed out of matter overdensities with wavenumbers as large as $k\approx 100$ Mpc${}^{-1}$. Here we forecast how well both the 21-cm global signal, and its fluctuations, could probe the matter power spectrum during cosmic dawn ($z=12-25$). We find that the long-wavelength modes (with $k\lesssim 40$ Mpc${}^{-1}$) are highly degenerate with astrophysical parameters, whereas the modes with $k=(40-80)$ Mpc${}^{-1}$ are more readily observable. This is further illustrated in terms of the principal components of the matter power spectrum, which peak at $k\sim 50$ Mpc${}^{-1}$ both for a typical experiment measuring the 21-cm global signal and its fluctuations. We find that, imposing broad priors on astrophysical parameters, a global-signal experiment can measure the amplitude of the matter power spectrum integrated over $k=(40-80)$ Mpc${}^{-1}$ with a precision of tens of percent. A fluctuation experiment, on the other hand, can constrain the power spectrum to a similar accuracy over both the $k=(40-60)$ Mpc${}^{-1}$ and $(60-80)$ Mpc${}^{-1}$ ranges even without astrophysical priors. The constraints outlined in this work would be able to test the behavior of dark matter at the smallest scales yet measured, for instance probing warm-dark matter masses up to $m_{\mathrm{WDM}}=8$ keV for the global signal and $14$ keV for the 21-cm fluctuations. This could shed light on the nature of dark matter beyond the reach of other cosmic probes.

    ↳ astro-ph.COhep-phPRD(2020)·126 citations
45. 45*

    Probing the Weak Gravity Conjecture in the Cosmic Microwave Background

    Martin Wolfgang Winkler🇸🇪 · Martina Gerbino🇮🇹 · Micol Benetti🇮🇹

    The weak gravity conjecture imposes severe constraints on natural inflation. A trans-Planckian axion decay constant can only be realized if the potential exhibits an additional (subdominant) modulation with sub-Planckian periodicity. The resulting wiggles in the axion potential generate a characteristic modulation in the scalar power spectrum of inflation which is logarithmic in the angular scale. The compatibility of this modulation is tested against the most recent Cosmic Microwave Background (CMB) data by Planck and BICEP/Keck. Intriguingly, we find that the modulation completely resolves the tension of natural inflation with the CMB. A Bayesian model comparison reveals that natural inflation with modulations describes all existing data equally well as the cosmological standard model $\Lambda$CDM. In addition, the bound of a tensor-to-scalar ratio r > 0.002 correlated with a striking small-scale suppression of the scalar power spectrum occurs. Future CMB experiments could directly probe the modulation through their improved sensitivity to smaller angular scales and possibly the measurement of spectral distortions. They could, thus, verify a key prediction of the weak gravity conjecture and provide dramatic new insights into the theory of quantum gravity.

    ↳ astro-ph.COhep-phhep-thPRD(2020)·8 citations
46. 46*

    Early Structure Formation Constraints on the Ultra-Light Axion in the Post-Inflation Scenario

    Vid Iršič🇺🇸 · Huangyu Xiao🇺🇸 · Matthew McQuinn🇺🇸

    Many works have concentrated on the observable signatures of the dark matter being an ultralight axion-like particle (ALP). We concentrate on a particularly dramatic signature in the late-time cosmological matter power spectrum that occurs if the symmetry breaking that establishes the ALP happens after inflation -- white-noise density fluctuations that dominate at small scales over the adiabatic fluctuations from inflation. These fluctuations alter the early history of nonlinear structure formation. We find that for symmetry breaking scales of $f_A\sim 10^{13}-10^{15}$GeV, which requires a high effective maximum temperature after inflation, ALP dark matter with particle mass of $m_A\sim 10^{-13}-10^{-20}$eV could significantly change the number of high-redshift dwarf galaxies, the reionization history, and the Ly$\alpha$ forest. We consider all three observables. We find that the Ly$\alpha$ forest is the most constraining of current observables, excluding $f_A\gtrsim 10^{15}$GeV ($m_A\lesssim 10^{-17}$eV) in the simplest model for the ALP and considerably lower values in models coupled to a hidden strongly interacting sector ($f_A\gtrsim 10^{13}$GeV and $m_A\lesssim 10^{-13}$eV). Observations that constrain the extremely high-redshift tail of reionization may disfavor similar levels of isocurvature fluctuations as the forest. Future $z\sim 20-30$ 21cm observations have the potential to improve these constraints further using that the supersonic motions of the isocurvature-enhanced abundance of $\sim 10^4{M}_{\odot }$ halos would shock heat the baryons, sourcing large BAO features.

    ↳ astro-ph.COastro-ph.GAhep-phhep-thPRD(2020)·78 citations
47. 47*

    LHCb gets closer to discovering the second doubly charmed baryon

    Marek Karliner🇮🇱 · Jonathan L. Rosner🇺🇸

    We comment on the results of the recent search by the LHCb collaboration for the doubly charmed baryon ${\Xi }_{cc}^{+}$.

    ↳ hep-exhep-phSCPMA(2020)·2 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.