Thu·Oct 24, 2019Thursday·October 24, 2019

1. 01*

   The Proton in High Definition: Revisiting Photon-Initiated Production in High Energy Collisions

   L.A. Harland-Lang🇬🇧

   We re-examine the current state of the art for the calculation of photon-initiated processes at the LHC, as formulated in terms of a photon PDF in the proton that may be determined rather precisely from the known proton structure functions. We in particular demonstrate that a by construction more precise calculation is provided by a direct application of the structure function approach, best known from the case of Higgs Boson production via vector boson fusion. This avoids any artificial scale variation uncertainties, which can otherwise be rather significant for processes calculated within the standard approach thus far. To understand the source of these, we present a detailed comparison of the structure function approach and its relation to the photon PDF. We then provide precise predictions for the photon-initiated contribution to lepton pair production at the LHC, including the lepton pair transverse momentum distribution. Thus, by a direct application of the structure function formalism we show how the contribution from initial-state photons at the LHC may for the first time be included with high precision in a universal and straightforward way, providing a high definition picture of the photon content of the proton.

   hep-phhep-exJHEP(2020)·24 citations
2. 02*

   Heavy sterile neutrino emission in core-collapse supernovae: Constraints and signatures

   Leonardo Mastrototaro🇮🇹 · Alessandro Mirizzi🇮🇹 · Pasquale Dario Serpico🇫🇷 · Arman Esmaili🇧🇷

   Heavy sterile neutrinos with masses $\mathcal{O}(100)$ MeV mixing with active neutrinos can be produced in the core of a collapsing supernova (SN). In order to avoid an excessive energy loss, shortening the observed duration of the SN 1987A neutrino burst, we show that the active-sterile neutrino mixing angle should satisfy ${\sin }^2\theta \lesssim 5\times 10^{-7}$. For a mixing with tau flavour, this bound is much stronger than the ones from laboratory searches. Moreover, we show that in the viable parameter space the decay of such "heavy" sterile neutrinos in the SN envelope would lead to a very energetic flux of daughter active neutrinos; if not too far below current limits, this would be detectable in large underground neutrino observatories, like Super-Kamiokande, as a (slightly time-delayed) high-energy bump in the spectrum of a forthcoming Galactic SN event.

   hep-phastro-ph.HEJCAP(2020)·65 citations
3. 03*

   $\Omega$ baryon spectrum and their decays in a constituent quark model

   Ming-Sheng Liu🇨🇳 · Kai-Lei Wang🇨🇳 · Qi-Fang Lü🇨🇳 · Xian-Hui Zhong🇨🇳

   Combining the recent developments of the observations of $\Omega$ sates we calculate the $\Omega$ spectrum up to the $N=2$ shell within a nonrelativistic constituent quark potential model. Furthermore, the strong and radiative decay properties for the $\Omega$ resonances within the $N=2$ shell are evaluated by using the masses and wave functions obtained from the potential model. It is found that the newly observed $\Omega (2012)$ resonance is most likely to be the spin-parity $J^P=3/2^{-}$ $1P$-wave state $\Omega (1^2{P}_{3/2^{-}})$, it also has a large potential to be observed in the $\Omega (1672)\gamma$ channel. Our calculation shows that the 1$P$-, 1$D$-, and 2$S$-wave $\Omega$ baryons have a relatively narrow decay width of less than 50 MeV. Based on the obtained decay properties and mass spectrum, we further suggest optimum channels and mass regions to find the missing $\Omega$ resonances via the strong and/or radiative decay processes.

   hep-phhep-exnucl-thPRD(2020)·57 citations
4. 04*

   The evolution of Information entropy components in Relativistic Heavy-Ion Collisions

   Fei Li🇨🇳 · Gang Chen🇨🇳

   Shannon information entropy provides an effective tool to study the evolution process in relativistic heavy-ion collisions. The time evolution process of thermodynamic entropy $S_{\mathrm{thermal}}$, multiple entropy $S_{\mathrm{mul}}$, and configuration entropy $S_{\mathrm{conf}}$ at RHIC is studied using the AMPT model to generate central Au-Au collisions. By superimposing the three kinds of information entropy, we can get a more complete information entropy of the system to describe the physical information of the relativistic heavy ion collision. The results show that the four stages of the time evolution process of the system entropy $S$ seem to correspond to the four physical processes in the relativistic heavy ion collision, indicating that the total entropy of the system can reflect the physical information in the relativistic heavy ion collision more accurately.

   hep-phnucl-thEPJA(2020)·6 citations
5. 05*

   Sea quark contributions to nucleon electromagnetic form factors with the nonlocal chiral effective Lagrangian

   Ming-Yang Yang🇨🇳 · Ping Wang🇨🇳

   The sea quark contributions to the nucleon electromagnetic form factors from up, down and strange quarks are studied with the nonlocal chiral effective Lagrangian. Both octet and decuplet intermediate states are included in the one loop calculation. Compared with the strange form factors, though their signs are the same, the absolute value of the light quark form factors are much larger. For both electric and magnetic form factors, the contribution from $d$ quark is larger than that from $u$ quark. The current lattice data for the light-sea quark form factors are between our sea quark results for $u$ and $d$.

   hep-phCPC(2020)·1 citation
6. 06*

   Trans-Planckian censorship and other swampland bothers addressed in warm inflation

   Arjun Berera🇬🇧 · Jaime R. Calderón🇬🇧

   The implications of the recently proposed Trans-Planckian censorship conjecture (TCC) are analyzed in the context of warm inflation. It is found that for a single-stage accelerated expansion the constraints imposed by the censorship are roughly the same as for cold inflation. Next, we study how a two-stage inflationary expansion with an intermediate radiation-dominated era can alleviate the bounds imposed by the censorship. For a demonstrative toy model we found $r<10^{-23}$, but can be $r<10^{-5}$ for a weaker form of TCC for the later stages of expansion, while still satisfying the other swampland conditions.

   hep-phastro-ph.COgr-qchep-thPRD(2019)·60 citations
7. 07*

   Nonminimal Inflation in Supersymmetric GUTs with $U(1{)}_R\times Z_n$ Symmetry

   Muhammad Atif Masoud🇵🇰 · Mansoor Ur Rehman🇵🇰 · Mian Muhammad Azeem Abid🇵🇰

   A supersymmetric hybrid inflation framework is employed to realize a class of non-minimal inflation models with $U(1{)}_R\times Z_n$ global symmetry. This framework naturally incorporates models based on grand unified theories by avoiding the most commonly faced monopole problem. The predictions of inflationary observables, the scalar spectral index $n_s=0.960-0.966$ and the tensor to scalar ratio $r=0.0031-0.0045$, are in perfect agreement with the Planck 2018 data. For sub-Planckian values of the field the $Z_n$ symmetry is only allowed for $n\le 4$.

   hep-phInt.J.Mod.Phys.D(2019)·9 citations
8. 08*

   Flavour Physics from Present to Future Colliders

   Monika Blanke🇩🇪

   In these proceedings we provide a brief overview of the status of flavour physics, with focus on opportunities to discover New Physics in flavour-violating decays at current and future colliders.

   hep-ph1 citation
9. 09*

   Multi-Channel Direct Detection of Light Dark Matter: Target Comparison

   Sinead M. Griffin🇺🇸 · Katherine Inzani🇺🇸 · Tanner Trickle🇺🇸 · Zhengkang Zhang🇺🇸 · Kathryn M. Zurek🇺🇸

   Direct detection experiments for light dark matter are making enormous leaps in reaching previously unexplored model space. Several recent proposals rely on collective excitations, where the experimental sensitivity is highly dependent on detailed properties of the target material, well beyond just nucleus mass numbers as in conventional searches. It is thus important to optimize the target choice when considering which experiment to build. We carry out a comparative study of target materials across several detection channels, focusing on electron transitions and single (acoustic or optical) phonon excitations in crystals, as well as the traditional nuclear recoils. We compare materials currently in use in nuclear recoil experiments (Si, Ge, NaI, CsI, CaWO${}_4$), a few which have been proposed for light dark matter experiments (GaAs, Al${}_2$O${}_3$, diamond), as well as 16 other promising polar crystals across all detection channels. We find that target- and dark matter model-dependent reach is largely determined by a small number of material parameters: speed of sound, electronic band gap, mass number, Born effective charge, high frequency dielectric constant, and optical phonon energies. We showcase, for each of the two benchmark models, an exemplary material which has a better reach than in any currently proposed experiment.

   hep-phcond-mat.mtrl-sciPRD(2020)·143 citations
10. 10*

    W-boson and trident production in TeV--PeV neutrino observatories

    Bei Zhou🇺🇸 · John F. Beacom🇺🇸

    Detecting TeV--PeV cosmic neutrinos provides crucial tests of neutrino physics and astrophysics. The statistics of IceCube and the larger proposed IceCube-Gen2 demand calculations of neutrino-nucleus interactions subdominant to deep-inelastic scattering, which is mediated by weak-boson couplings to nuclei. The largest such interactions are W-boson and trident production, which are mediated instead through photon couplings to nuclei. In a companion paper [1], we make the most comprehensive and precise calculations of those interactions at high energies. In this paper, we study their phenomenological consequences. We find that: (1) These interactions are dominated by the production of on-shell W-bosons, which carry most of the neutrino energy, (2) The cross section on water/iron can be as large as 7.5%/14% that of charged-current deep-inelastic scattering, much larger than the quoted uncertainty on the latter, (3) Attenuation in Earth is increased by as much as 15%, (4) W-boson production on nuclei exceeds that through the Glashow resonance on electrons by a factor of $\simeq$ 20 for the best-fit IceCube spectrum, (5) The primary signals are showers that will significantly affect the detection rate in IceCube-Gen2; a small fraction of events give unique signatures that may be detected sooner.

    hep-phastro-ph.HEhep-exPRD(2020)·69 citations
11. 11*

    Classification of dark pion multiplets as dark matter candidates and collider phenomenology

    Hugues Beauchesne🇮🇱 · Giovanni Grilli di Cortona🇵🇱

    New confining sectors can contain a set of pseudo-Goldstone mesons that exhibit a complicated structure in terms of stability and relative masses. Stable ones can act as dark matter candidates, while their interactions with the unstable ones determine their relic abundances. The overall structure, by specifying which channels are kinematically forbidden or not, affects the cosmology, constraints and collider phenomenology. In this paper, we present a classification of these pseudo-Goldstone meson structures. We find that the structures can be classified into three categories, corresponding to strong, suppressed and essentially non-existent constraints from indirect detection. Limits on decay lengths of the unstable mesons and dark jet properties are presented for several benchmark models.

    hep-phhep-exJHEP(2020)·31 citations
12. 12*

    Is it possible to explain the muon and electron $g-2$ in a $Z^{\prime }$ model?

    A. E. Cárcamo Hernández🇨🇱 · S. F. King🇬🇧 · H. Lee🇬🇧 · S. J. Rowley🇬🇧

    In order to address this question, we consider a simple renormalisable and gauge invariant model in which the $Z^{\prime }$ only has couplings to the electron and muon and their associated neutrinos, arising from mixing with a heavy vector-like fourth family of leptons. Within this model we discuss the contributions to the electron and muon anomalous magnetic moments from $Z^{\prime }$ exchange, subject to the constraints from $\mu \to e\gamma$ and neutrino trident production. Using analytic and numerical arguments, we find that such a $Z^{\prime }$ model can account for either the electron or the muon $g-2$ anomalies, but not both, while remaining consistent with the experimental constraints from $\mu \to e\gamma$ and neutrino trident production.

    hep-phPRD(2020)·60 citations
13. 13*

    Model-independent sensitivity estimates for the electromagnetic dipole moments of the top quark at the Large Hadron Collider and beyond

    M. Koksal🇹🇷

    As the heaviest known fundamental particle, the top quark ensures testing of the Standard Model and occupies a significant role in a lot of theories of new physics beyond the Standard Model. Up to now, the top quark has been only generated at the Tevatron and the Large Hadron Collider. However, one of the most important tasks of the physics program at the Large Hadron Collider is the investigation of the anomalous top quark interactions. In addition, the production of single top quarks, though rarer than production in pairs, presents us a different way to study the top quark produced via the electroweak interaction. This makes single top quark production an important signature for studying the properties of the top quark. Hence, we examine the anomalous $t\bar{t}\gamma$ interactions to investigate limits on the anomalous $a_A$ and $a_V$ couplings through single top quark production of the process $pp\to p{\gamma }^{\ast }p\to ptWX$ at the Large Hadron Collider, the High Luminosity Large Hadron Collider and High Energy Large Hadron Collider. The best limits obtained on the anomalous $a_A$ and $a_V$ couplings through the subprocess ${\gamma }^{\ast }b\to Wt$ at the High Energy Large Hadron Collider with $L_{int}=15$ ab${}^{-1}$ at $68\%$ Confidence Level are found to be $|a_A|=0.0590$ and $a_V=[-0.3202;0.0108]$. Therefore, we understand that ${\gamma }^{\ast }p$ collisions at the High Energy Large Hadron Collider improves the sensitivity limits of the anomalous coupling parameters according to previous studies.

    hep-phNPB(2020)·1 citation
14. 14*

    Photon generation via dynamical Casimir effect in an optomechanical cavity as a closed quantum system

    Nicolás F. Del Grosso🇦🇷 · Fernando C. Lombardo🇦🇷 · Paula I. Villar🇦🇷

    We present an analytical and numerical analysis of the particle creation in an optomechanical cavity in parametric resonance. We treat both the electromagnetic field and the mirror as quantum degrees of freedom and study the dynamical evolution as a closed quantum system. We consider different initial states and investigate the spontaneous emission of photons from phonons in the mirror. We find that for initial phononic product states the evolution of the photon number can be described as a non-harmonic quantum oscillator, providing an useful tool so as to estimate the maximum and mean number of photons produced for arbitrary high energies. The efficiency of this mechanism is further analyzed for a detuned cavity as well as the possibility of stimulating the photon production by adding some initial ones to the cavity. We also find relationships for the maximum and mean entanglement between the mirror and the wall in these states. Additionally we study coherent states for the motion of the mirror to connect this model with previous results from quantum field theory with a classical mirror. Finally we study thermal states of phonons in the wall and the equilibration process that leads to a stationary distribution.

    ↳ quant-phcond-mat.otherhep-phPRA(2019)·12 citations
15. 15*

    Meson interactions at large $N_c$ from Lattice QCD

    Fernando Romero-López🇪🇸 · Andrea Donini🇪🇸 · Pilar Hernández🇪🇸 · Carlos Pena🇪🇸

    We report on the computation of the scaling of QCD observables with the number of colours, $N_c$. For this, we use dynamical configurations with four active flavours, $N_f=4$, and values of $N_c=3-6$. We study the meson masses and decay constants, and compute the leading and subleading contributions to the Low Energy Constants (LECs) of the chiral Lagrangian. We also explore $\pi \pi$ scattering in the $I=2$ channel, and compute the $K\to \pi$ weak decay matrix elements. We comment on the relation of the latter to $K\to \pi \pi$ processes and the $\Delta I=1/2$ rule.

    ↳ hep-lathep-phPoS(2019)·6 citations
16. 16*

    Search for exotic decays at NA62

    Roberta Volpe🇧🇪

    The features of the NA62 experiment at the CERN SPS (high intensity setup, trigger system flexibility, high frequency tracking of beam particles, redundant particle identification, and high-efficiency photon vetoes) make NA62 particularly suitable to search for long-lived, weakly coupled particles within Beyond the Standard Model (BSM) physics, using kaon and pion decays as well as operating the experiment in dump mode. The NA62 sensitivity for searches of Dark Photons, Heavy Neutral Leptons and Axion-Like Particles are presented, together with prospects for future data taking at the NA62 experiment.

    ↳ hep-exhep-ph8 citations
17. 17*

    Direct probe of ferromagnetic proximity effect at the interface in Fe/SnTe heterostructure by polarized neutron reflectometry

    Ryota Akiyama · Ryo Ishikawa🇯🇵 · Kazuhiro Akutsu · Ryosuke Nakanishi · Yuta Tomohiro · Kazumi Watanabe🇯🇵 · Kazuki Iida · Masanori Mitome · Shuji Hasegawa🇯🇵 · Shinji Kuroda

    Introducing magnetic order into a topological insulator (TI) system has been attracting much attention with an expectation of realizing exotic phenomena such as quantum anomalous Hall effect (QAHE) or axion insulator states. The magnetic proximity effect (MPE) is one of the promising schemes to induce the magnetic order on the surface of TI without introducing disorder accompanied by doping magnetic impurities in TI. In this study, we investigate the MPE at the interface of a heterostructure consisting of a topological crystalline insulator (TCI) SnTe and Fe by employing polarized neutron reflectometry. The ferromagnetic order penetrates $\sim$ 3 nm deep into the SnTe layer from the interface with Fe, which persists up to room temperature. Our findings demonstrate that the interfacial magnetism is induced by the MPE on the surface of TCI preserving the coherent topological states, which is essential for the bulk-edge correspondence, without introducing disorder arising from a random distribution magnetic impurities. This opens up a way for realizing next generation electronics, spintronics, and quantum computational devices by making use of the characteristics of TCI.

    ↳ cond-mat.mtrl-scicond-mat.mes-hallhep-phJ.Phys.Chem.Lett.(2022)·0 citations
18. 18*

    Unified description of hadron yield ratios from dynamical core-corona initialization

    Yuuka Kanakubo🇯🇵 · Yasuki Tachibana🇺🇸 · Tetsufumi Hirano🇯🇵

    We develop the dynamical core-corona initialization framework as a phenomenological description of the formation of quark gluon plasma (QGP) fluids in high-energy nuclear collisions. Using this framework, we investigate the fraction of the fluidized energy to the total energy and strange hadron yield ratios as functions of multiplicity and scrutinize the multiplicity scaling of hadron yield ratios recently reported by the ALICE Collaboration. Our results strongly indicate that the QGP fluids are partly formed even at the averaged multiplicity for nonsingle diffractive p+p events.

    ↳ nucl-thhep-phnucl-exPRC(2020)·74 citations
19. 19*

    Spectral-shift and scattering-equivalent Hamiltonians on a coarse momentum grid

    María Gómez-Rocha🇪🇸 · Enrique Ruiz Arriola🇪🇸

    The solution of the scattering problem based on the Lippmann-Schwinger equation requires in many cases a discretization of the spectrum in the continuum which does not respect the unitary equivalence of the S-matrix on the finite grid. We present a new prescription for the calculation of phase shifts based on the shift that is produced in the spectrum of a Chebyshev-angle variable. This is analogous to the energy shift that is produced in the energy levels of a scattering process in a box, when an interaction is introduced. Our formulation holds for any momentum grid and preserves the unitary equivalence of the scattering problem on the finite momentum grid. We illustrate this procedure numerically considering the non-relativistic NN case for ${}^1{S}_0$ and ${}^3{S}_1$ channels. Our spectral shift formula provides much more accurate results than the previous ones and turns out to be at least as competitive as the standard procedures for calculating phase shifts.

    ↳ nucl-thhep-phquant-phPLB(2020)·7 citations
20. 20*

    Implications for Dark Matter Direct Detection in the Presence of LIGO-Motivated Primordial Black Holes

    Mark P. Hertzberg🇺🇸 · Enrico D. Schiappacasse🇨🇳 · Tsutomu T. Yanagida🇨🇳

    We discuss formation of dark matter (DM) mini-halos around primordial black holes (PBHs) and its implication on DM direct detection experiments, including axion searches. Motivated by LIGO observations, we consider $f_{\text{DM}}\simeq 0.01$ as the fraction of DM in PBHs with masses $10M_{\odot }-70M_{\odot }$. In this case, we expect the presence of dressed PBHs after Milky Way halo formation with mini-halo masses peaked around $M_{\text{halo}}\sim (50-55)M_{\text{PBH}}$. We analyze the effect of tidal forces acting on dressed PBHs within the Milky Way galaxy. In the solar neighborhood, the mini-halos are resistant against tidal disruption from the mean-field potential of the galaxy and encounters with stars, but they undergo a small level of disruption caused by disk shocking. The presence of mini-halos around LIGO-motivated PBHs today could reduce by half the local dark matter background. High-resolution simulations are encouraged. If the proposed scenario is realized, chances of direct detection of DM would decrease.

    ↳ astro-ph.COastro-ph.GAgr-qchep-ph+1PLB(2020)·21 citations
21. 21*

    Lattice QCD study of the rare kaon decay $K^{+}\to {\pi }^{+}\nu \bar{\nu }$ at a near-physical pion mass

    Norman H. Christ🇺🇸 · Xu Feng🇨🇳 · Antonin Portelli🇬🇧 · Christopher T. Sachrajda🇬🇧

    The rare kaon decay $K^{+}\to {\pi }^{+}\nu \bar{\nu }$ is an ideal process in which to search for signs of new physics and is the primary goal of the NA62 experiment at CERN. In this paper we report on a lattice QCD calculation of the long-distance contribution to the $K^{+}\to {\pi }^{+}\nu \bar{\nu }$ decay amplitude at the near-physical pion mass $m_{\pi }=170$ MeV. The calculations are however, performed on a coarse lattice and hence with a lighter charm quark mass ($m_c^{\overline{\mathrm{MS}}}(\text{mbox}3GeV)=750$ MeV) than the physical one. The main aims of this study are two-fold. Firstly we study the momentum dependence of the amplitude and conclude that it is very mild so that a computation at physical masses even at a single kinematic point would provide a good estimate of the long-distance contribution to the decay rate. Secondly we compute the contribution to the branching ratio from the two-pion intermediate state whose energy is below the kaon mass and find that it is less than 1% after its exponentially growing unphysical contribution has been removed and that the corresponding non-exponential finite-volume effects are negligibly small.

    ↳ hep-lathep-exhep-phPRD(2019)·34 citations
22. 22*

    Linear Point and Sound Horizon as Purely Geometric standard rulers

    Márcio O'Dwyer🇺🇸 · Stefano Anselmi🇫🇷 · Glenn D. Starkman🇺🇸 · Pier-Stefano Corasaniti🇫🇷 · Ravi K. Sheth🇺🇸 · Idit Zehavi🇺🇸

    The Baryon Acoustic Oscillations feature (BAO) imprinted in the clustering correlation function is known to furnish us cosmic distance determinations that are independent of the cosmological-background model and the primordial perturbation parameters. These measurements can be accomplished rigorously by means of the Purely Geometric BAO methods. To date two different Purely Geometric BAO approaches have been proposed. The first exploits the linear-point standard ruler. The second, called correlation-function model-fitting, exploits the sound-horizon standard ruler. A key difference between them is that, when estimated from clustering data, the linear point makes use of a cosmological-model-independent procedure to extract the ratio of the ruler to the cosmic distance, while the correlation-function model-fitting relies on a phenomenological cosmological model for the correlation function. Nevertheless the two rulers need to be precisely defined independently of any specific observable. We define the linear point and sound horizon and we characterize and compare the two rulers' cosmological-parameter dependence. We find that they are both geometrical within the required accuracy, and they have the same parameter dependence for a wide range of parameter values. We estimate the rulers' best-fit values and errors given the cosmological constraints obtained by the Planck Satellite team from the CMB measurements. We do this for three different cosmological models encompassed by the Purely Geometric BAO methods. In each case we find that the relative errors of the two rulers coincide and they are insensitive to the assumed cosmological model. Interestingly both the linear point and the sound horizon shift by $0.5\sigma$ when we do not fix the spatial geometry to be flat in LCDM. This points toward a sensitivity of the rulers to different cosmological models when they are estimated from the CMB.

    ↳ astro-ph.COgr-qchep-phhep-thPRD(2020)·38 citations
23. 23*

    Improved BBN Constraints on the Variation of the Gravitational Constant

    James Alvey🇬🇧 · Nashwan Sabti🇬🇧 · Miguel Escudero🇬🇧 · Malcolm Fairbairn🇬🇧

    Big Bang Nucleosynthesis (BBN) is very sensitive to the cosmological expansion rate. If the gravitational constant $G$ took a different value during the nucleosynthesis epoch than today, the primordial abundances of light elements would be affected. In this work, we improve the bounds on this variation using recent determinations of the primordial element abundances, updated nuclear and weak reaction rates and observations of the Cosmic Microwave Background (CMB). When combining the measured abundances and the baryon density from CMB observations by Planck, we find $G_{\mathrm{BBN}}/G_0=0.99_{-0.05}^{+0.06}$ at $2\sigma$ confidence level. If the variation of $G$ is linear in time, we find $\dot{G}/G_0=0.7_{-4.3}^{+3.8}\times 10^{-12}{\mathrm{yr}}^{-1}$, again at $2\sigma$. These bounds are significantly stronger than those from previous primordial nucleosynthesis studies, and are comparable and complementary to CMB, stellar, solar system, lunar laser ranging, pulsar timing and gravitational wave constraints.

    ↳ astro-ph.COhep-phhep-thEPJC(2020)·104 citations
24. 24*

    Topics in gravity SCET: the diff Wilson lines and reparametrization invariance

    Sabyasachi Chakraborty🇺🇸 · Takemichi Okui🇺🇸 · Arash Yunesi🇺🇸

    Two topics in soft collinear effective theory (SCET) for gravitational interactions are explored. First, the collinear Wilson lines---necessary building blocks for maintaining multiple copies of diffeomorphism invariance in gravity SCET---are extended to all orders in the SCET expansion parameter $\lambda$, where it has only been known to $O(\lambda )$ in the literature. Second, implications of reparametrization invariance (RPI) for the structure of gravity SCET lagrangians are studied. The utility of RPI is illustrated by an explicit example in which $O({\lambda }^2)$ hard interactions of a collinear graviton are completely predicted by RPI from its $O(\lambda )$ hard interactions. It is also pointed out that the multiple diffeomorphism invariances and RPI together require certain relations among $O(\lambda )$ terms, thereby reducing the number of $O(\lambda )$ terms that need to be fixed by matching onto the full theory in the first place.

    ↳ hep-thgr-qchep-phPRD(2020)·7 citations
25. 25*

    New Early Dark Energy

    Florian Niedermann🇩🇰 · Martin S. Sloth🇩🇰

    New measurements of the expansion rate of the Universe have plunged the standard model of cosmology into a severe crisis. In this letter, we propose a simple resolution to the problem that relies on a first order phase transition in a dark sector in the early Universe, before recombination. This will lead to a short phase of a New Early Dark Energy (NEDE) component and can explain the observations. We model the false vacuum decay of the NEDE scalar field as a sudden transition from a cosmological constant source to a decaying fluid with constant equation of state. The corresponding fluid perturbations are covariantly matched to the adiabatic fluctuations of a sub-dominant scalar field that triggers the phase transition. Fitting our model to measurements of the cosmic microwave background (CMB), baryonic acoustic oscillations (BAO, and supernovae (SNe) yields a significant improvement of the best-fit compared with the standard cosmological model without NEDE. We find the mean value of the present Hubble parameter in the NEDE model to be $H_0=71.4\pm 1.0\text{km}{\text{s}}^{-1}{\text{Mpc}}^{-1}$ ($68\%$ C.L.).

    ↳ astro-ph.COhep-phhep-thPRD(2021)·297 citations
26. 26*

    Direct Measurement of Upward-going Ultrahigh Energy Dark Matter at the Pierre Auger Observatory

    Ye Xu🇨🇳

    In the present paper, it is assumed that there exist two dark matter particles: superheavy dark matter particles (SHDM), whose mass $\sim$ inflaton mass, and light fermion dark matter (DM) particles which are the ultrahigh energy (UHE) products of its decay. The Earth will be taken as a detector to directly search for the UHE DM particles. These upward-going particles, which pass through the Earth and air and interact with nuclei, can be detected by the fluorescence detectors (FD) of the Pierre Auger observatory (Auger), via fluorescent photons due to the development of an EAS. The numbers and fluxes of expected UHE DM particles are evaluated in the incoming energy range between 1 EeV and 1 ZeV with the different lifetimes of decay of SHDM and mass of $Z^{\prime }$. According to the Auger data from 2008 to 2019, the upper limit for UHE DM fluxes is estimated at 90\% C.L. with the FD of Auger. UHE DM particles could be directly detected in the energy range between O(1EeV) and O(10EeV) with the FD of Auger. Thus this might prove whether there exist SHDM particles in the Universe.

    ↳ astro-ph.HEhep-phPubl.Astron.Soc.Jap.(2021)·1 citation
27. 27*

    RationalizeRoots: Software Package for the Rationalization of Square Roots

    Marco Besier🇩🇪 · Pascal Wasser🇩🇪 · Stefan Weinzierl🇩🇪

    The computation of Feynman integrals often involves square roots. One way to obtain a solution in terms of multiple polylogarithms is to rationalize these square roots by a suitable variable change. We present a program that can be used to find such transformations. After an introduction to the theoretical background, we explain in detail how to use the program in practice.

    ↳ cs.MScs.SChep-phhep-th+2Comput.Phys.Commun.(2020)·84 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.