Tue·Dec 11, 2018Tuesday·December 11, 2018

1. 01*

   Jet splitting functions in the vacuum and in a QCD medium

   Hai Tao Li🇺🇸 · Ivan Vitev🇺🇸

   The two-prong structure related to the leading subjets inside a reconstructed jet opens new avenues toward precision constraints on the in-medium modification of parton showers. In this talk, we present the first resummed calculation of the soft-dropped groomed momentum sharing distribution, or the jet splitting function, in heavy-ion collisions for both light jets and heavy flavor tagged jets. Existing light jet splitting function data from the STAR experiment at RHIC and the CMS experiment at LHC can be understood in the unified framework of soft-collinear effective theory with Glauber gluon interactions. For heavy flavor jets, very interestingly, the momentum sharing distribution of b-tagged jets is more strongly modified in comparison to the one for light jets, which provides a novel handle on mass corrections to in-medium parton showers that are at present difficult to constraint using inclusive heavy meson production.

   hep-phPoS(2018)·1 citation
2. 02*

   Baryon fields with $U_L(3)\times U_R(3)$ chiral symmetry V: Pion-Nucleon and Kaon-Nucleon $\Sigma$ Terms

   V. Dmitrasinovic🇷🇸 · Hua-Xing Chen🇨🇳 · Atsushi Hosaka🇯🇵

   We have previously calculated the pion-nucleon ${\Sigma }_{\pi N}$ term in the chiral mixing approach with $u,d$ flavors only, and found the lower bound ${\Sigma }_{\pi N}\ge \left(1+\frac{16}{3}{\sin }^2\theta \right)\frac{3}{2}\left(m_u^0+m_d^0\right)$. The mixing angle $\theta$ can be calculated as ${\sin }^2\theta =\frac{3}{8}\left(g_A^{(0)}+g_A^{(3)}\right)$. With presently accepted values of current quark masses, this leads to ${\Sigma }_{\pi N}\ge 58.0\pm 4.5\begin{array}{l}+11.4\\ -6.5\end{array}$ MeV, which is in agreement with the values extracted from experiments, and substantially higher than most previous two-flavour calculations. The causes of this enhancement are: 1) the large, ($\frac{16}{3}\simeq 5.3$), purely $S{U}_L(2)\times S{U}_R(2)$ algebraic factor, 2) the admixture of the $[(1,\frac{1}{2})\oplus (\frac{1}{2},1)]$ chiral multiplet component in the nucleon, whose presence has been known for some time, but that had not been properly taken into account, yet. We have now extended these calculations of ${\Sigma }_{\pi N}$ to three light flavours, i.e., to $S{U}_L(3)\times S{U}_R(3)$ multiplet mixing. Phenomenology of chiral $S{U}_L(3)\times S{U}_R(3)$ multiplet mixing demands the presence of three chiral $S{U}_L(3)\times S{U}_R(3)$ multiplets in order to successfully reproduce the baryons' flavor-octet and flavor-singlet axial currents, as well as the baryon anomalous magnetic moments. The physical significance of these results lies in the fact that they show no need for $q^4\bar{q}$ components, and in particular, no need for an $s\bar{s}$ component in the nucleon, in order to explain the large "observed" ${\Sigma }_{\pi N}$ value. We also predict the experimentally unknown kaon-nucleon sigma term ${\Sigma }_{KN}$.

   hep-phPRC(2016)·18 citations
3. 03*

   Testing Leptoquark and $Z^{\prime }$ Models via $B\to K_1(1270,1400){\mu }^{+}{\mu }^{-}$ Decays

   Zhuo-Ran Huang🇨🇳 · Muhammad Ali Paracha🇵🇰 · Ishtiaq Ahmed🇵🇰 · Cai-Dian Lü🇨🇳

   The measurements of $R_{K^{(\ast )}}=\mathcal{B}(B\to K^{(\ast )}{\mu }^{+}{\mu }^{-})/\mathcal{B}(B\to K^{(\ast )}{e}^{+}{e}^{-})$ in recent years have hinted lepton flavor non-universality and thus drawn widespread attentions. If these anomalies are induced by new physics (NP), deviations from the SM predictions may also be found in other channels via the same process at the quark level. In this work, we study in $B\to K_1(1270,1400){\mu }^{+}{\mu }^{-}$ decays the effects of two popular classes of NP models which can address the $b\to s$ anomalies, i.e. the leptoquark models and the $Z^{\prime }$ models. By assuming that NP only affects the $b\to s{\mu }^{+}{\mu }^{-}$ transition, we find that the unpolarized and polarized lepton flavor universality (LFU) ratios $R_{K_1^{(L,T)}(1270)}$ are useful to distinguish among the NP models (scenarios) and the SM because they are sensitive to the NP effects and insensitive to the mixing angle ${\theta }_{K_1}$, while the $R_{K_1^{(L,T)}(1400)}$ are sensitive to both NP and ${\theta }_{K_1}$. Another ratio $R_{\mu }(K_1)=\mathcal{B}(B\to K_1(1400){\mu }^{+}{\mu }^{-})/\mathcal{B}(B\to K_1(1270){\mu }^{+}{\mu }^{-})$ is shown to depend weekly on the effects from the NP models (scenarios) under consideration, and thus can be used to determine the ${\theta }_{K_1}$ and complement the $R_{K_1^{(L,T)}}$ in the probe for NP.

   hep-phhep-exPRD(2019)·21 citations
4. 04*

   New mechanism of producing superheavy Dark Matter

   Eugeny Babichev🇫🇷 · Dmitry Gorbunov🇷🇺 · Sabir Ramazanov🇨🇿

   We study in detail the recently proposed mechanism of generating superheavy Dark Matter with the mass larger than the Hubble rate at the end of inflation. A real scalar field constituting Dark Matter linearly couples to the inflaton. As a result of this interaction, the scalar gets displaced from its zero expectation value. This offset feeds into the energy density of Dark Matter. This mechanism is universal and can be implemented in a generic inflationary scenario. Phenomenology of the model is comprised of Dark Matter decay into inflatons, which in turn decay into Standard Model species triggering cascades of high energy particles contributing to the cosmic ray flux. We evaluate the lifetime of Dark Matter and obtain limits on the inflationary scenarios, where this mechanism does not lead to the conflict with the Dark Matter stability considerations/studies of cosmic ray propagation.

   hep-phastro-ph.COastro-ph.HEhep-thPLB(2019)·15 citations
5. 05*

   Showcasing HH production: Benchmarks for the (HL-)LHC

   Philipp Basler🇩🇪 · Sally Dawson🇺🇸 · Christoph Englert🇬🇧 · Milada M. Mühlleitner🇩🇪

   Current projections suggest that the LHC will have only limited sensitivity to di-Higgs production in the Standard Model (SM), possibly even after the completion of its high luminosity phase. Multi-Higgs final states play a fundamental role in many extensions of the SM as they are intrinsically sensitive to modifications of the Higgs sector. Therefore, any new observation in multi-Higgs final states could be linked to a range of beyond the SM (BSM) phenomena that are not sufficiently addressed by the SM. Extensions of the Higgs sector typically lead to new phenomenological signatures in multi-Higgs final states that are vastly different from the SM expectation. In this work, we provide a range of signature-driven benchmark points for resonant and non-resonant BSM di-Higgs production that motivate non-SM kinematic correlations and multi-fermion discovery channels. Relying on theoretically well-motivated assumptions, special attention is devoted to the particular case where the presence of new physics will dominantly manifest itself in multi-Higgs final states.

   hep-phPRD(2019)·45 citations
6. 06*

   Franz-Keldysh effect in strong-field QED

   Hidetoshi Taya🇨🇳

   We studied a QED analog of the Franz-Keldysh effect, and the interplay between the non-perturbative (the Schwinger mechanism) and the perturbative particle production mechanism from the vacuum in the presence of a strong slow field superimposed by a weak field. We found that the Franz-Keldysh effect significantly affects the particle production: (i) the perturbative particle production occurs even below the threshold energy; (ii) the perturbative production becomes the most efficient just above the threshold energy; and (iii) an oscillating behavior appears in the production number above the threshold energy. These non-trivial changes are suppressed only weakly by powers of the critical field strength of QED. A relation to the dynamically assisted Schwinger mechanism and implications to experiments are also discussed.

   hep-phhep-thnucl-thphysics.plasm-ph+1PRD(2019)·31 citations
7. 07*

   Investigating Sterile Neutrino Flux in the Solar Neutrino Data

   Ankush🇮🇳 · Rishu Verma🇮🇳 · Gazal Sharma🇮🇳 · B.C.Chauhan🇮🇳

   There are compelling evidences for the existence of a fourth degree of freedom of neutrinos i.e. sterile neutrino. In the recent studies the role of sterile component of neutrinos has been found to be crucial, not only in particle physics, but also in astrophysics and cosmology. This has been proposed to be one of the potential candidates of dark matter. In this work we investigate the updated solar neutrino data available from all the relevant experiments including Borexino and KamLAND solar phase in a model independent way, and obtain bounds on the sterile neutrino component present in the solar neutrino flux. The mystery of the missing neutrinos is further deepening as subsequent experiments are coming up with their results. The energy spectrum of solar neutrinos, as predicted by Standard Solar Models (SSM), is seen by neutrino experiments at different parts as they are sensitive to various neutrino energy ranges. It is interesting to note that more than $98\%$ of the calculated standard model solar neutrino flux lies below $1MeV$. Therefore, the study of low energy neutrinos can give us better understanding and the possibility to know about the presence of antineutrino and sterile neutrino components in solar neutrino flux. As such, this work becomes interesting as we include the data from medium energy ($\sim 1MeV$) experiments i.e. Borexino and KamLAND solar phase. In our study we retrieve the bounds existing in literature, and rather provide more stringent limits on sterile neutrino(${\nu }_s$) flux available in solar neutrino data.

   hep-phAdv.High Energy Phys.(2019)·2 citations
8. 08*

   ${\epsilon }^{\prime }/\epsilon$ in and beyond the Standard Model

   Jason Aebischer🇩🇪

   Estimates of the CP violating observable ${\epsilon }^{\prime }/\epsilon$ have gained some attention in the past few years. Depending on the long-distance treatment used, they exhibit up to $2.9\sigma$ deviation from the experimentally measured value. Such a deviation motivates the investigation of New Physics (NP) effects in the process $K\to \pi \pi$. In my talk I will review the Standard Model (SM) prediction for ${\epsilon }^{\prime }/\epsilon$, with a special focus on the Dual QCD approach. On the NP side, I will discuss a recent computation of the hadronic matrix elements of NP operators. Furthermore a master formula for BSM effects in ${\epsilon }^{\prime }/\epsilon$ is presented. Finally, a treatment of ${\epsilon }^{\prime }/\epsilon$ using the SM effective theory (SMEFT) will be discussed together with possible correlations to other observables.

   hep-phhep-exhep-lat1 citation
9. 09*

   Loop functions at finite temperature from perturbation theory to lattice QCD

   Antonio Vairo🇩🇪

   We review our present knowledge of the Polyakov loop, the correlator of Polyakov loops and the singlet correlator in thermal QCD from the point of view of perturbation theory and lattice QCD.

   hep-phhep-latPoS(2018)·0 citations
10. 10*

    Removing infrared divergences from two-loop integrals

    Charalampos Anastasiou🇨🇭 · George Sterman🇺🇸

    Feynman amplitudes at higher orders in perturbation theory generically have complex singular structures. Notwithstanding the emergence of many powerful new methods, the presence of infrared divergences poses significant challenges for their evaluation. In this article, we develop a systematic method for the removal of the infrared singularities, by adding appropriate counterterms that approximate and cancel divergent limits point-by-point at the level of the integrand. We provide a proof of concept for our method by applying it to master-integrals that are found in scattering amplitudes for representative two-to-two scattering processes of massless particles. We demonstrate that, after the introduction of counterterms, the remainder is finite in four dimensions. In addition, we find in these cases that the complete singular dependence of the integrals can be obtained simply by analytically integrating the counterterms. Finally, we observe that our subtraction method can be also useful in order to extract in a simple way the asymptotic behavior of Feynman amplitudes in the limit of small mass parameters.

    hep-phhep-thJHEP(2019)·76 citations
11. 11*

    Disentangling Seesaw in the Minimal Left-Right Symmetric Model

    Goran Senjanovic🇮🇹 · Vladimir Tello🇮🇹

    In a recent Letter we presented a systematic way of testing the seesaw origin of neutrino mass in the context of the Minimal Left-Right Symmetric Model. The essence of the program is to exploit lepton number violating decays of doubly charged scalars, particles which lie at the heart of the Higgs-mechanism-based seesaw, to probe the Dirac neutrino mass term which in turn enters directly into a number of physical processes including the decays of right-handed neutrinos into the $W$ boson and left-handed charged leptons. In this longer version we discuss at length these and related processes, and offer some missing technical details. We also carefully analyze the physically appealing possibility of parity conserving Yukawa sector showing that the neutrino Dirac mass matrix can be analytically expressed as a function of light and heavy neutrino masses and mixing, without resorting to any additional discrete symmetries, a context in which the seesaw mechanism can be disentangled completely.When parity does get broken, we show that, in the general case, only the Hermitian part of the Dirac mass term is independent which substantially simplifies the task of testing experimentally the origin of neutrino mass. We illustrate this program through some physical examples that allow simple analytical expressions. Our work shows that the Minimal Left-Right Symmetric Model is a self-contained theory of neutrino mass which can be in principle tested at the LHC or the next hadron collider.

    hep-phhep-exPRD(2019)·38 citations
12. 12*

    Exotic ${\Omega }_c^0$ baryons from meson-baryon scattering

    Gloria Montana🇪🇸 · Angels Ramos🇪🇸 · Albert Feijoo🇨🇿

    A meson-baryon interaction in the charm $+1$, strangeness $-2$ and isospin $0$ sector is built from a t-channel vector meson exchange model employing effective Lagrangians. The implementation of coupled-channel unitarization in the s-wave scattering amplitudes gives rise to two structures that have similar masses and widths to those of the ${\Omega }_c(3050{)}^0$ and ${\Omega }_c(3090{)}^0$ states recently observed by the LHCb collaboration. A meson-baryon molecular interpretation of these resonances would assign their spin-parity to be $J^P=1/2^{-}$.

    hep-phnucl-thJ.Phys.Conf.Ser.(2019)·1 citation
13. 13*

    Neutral and Charged Higgs boson phenomenology at the LHeC and FCC-eh

    Siba Prasad Das🇨🇴 · Marek Nowakowski🇨🇴 · J. Hernández-Sánchez🇲🇽 · Stefano Moretti🇬🇧 · Alfonso Rosado🇲🇽

    We have analyzed the prospects of observing the lightest CP-even neutral Higgs boson ($h_1$) via decays into $b\bar{b}$ pairs in the neutral and charged current production processes $e^{-}q\to e^{-}{h}_{1}q$ and $e^{-}q\to {\nu }_e{h}_1{q}^{\prime }$, respectively, at the planneded large Hadron electron Collider (LHeC), with an $e^{-}$ beam energy of 60 GeV and a $p$ beam energy of 7 TeV. We also focus on observing a relatively light charged Higgs boson ($h^{-}$) via its production mode $e^{-}b\to {\nu }_e{h}^{-}b$ followed by the decays $h^{-}\to s\bar{c}+s\bar{u}$ at the upcoming Future Circular Collider in hadron-electron mode (FCC-eh) with $\sqrt{s}\approx 3.5$ TeV. We have performed our analysis in the framework of the Next-to-Minimal Supersymmetric Standard Model (NMSSM) wherein the intermediate Higgs boson ($h_2$) is Standard Model (SM)-like. We have considered constraints from Dark Matter (DM), superparticle and the Higgs boson data. In both analyses, we have carried out signal and background computations with selections optimized to the model at hand and found that in both cases it is possible to get large significances for low mass Higgs bosons.

    hep-phhep-ex1 citation
14. 14*

    Master Majorana neutrino mass parametrization

    Isabel Cordero-Carrión🇪🇸 · Martin Hirsch🇪🇸 · Avelino Vicente🇪🇸

    After introducing a master formula for the Majorana neutrino mass matrix we present a master parametrization for the Yukawa matrices automatically in agreement with neutrino oscillation data. This parametrization can be used for any model that induces Majorana neutrino masses. The application of the master parametrization is also illustrated in an example model, with special focus on its lepton flavor violating phenomenology.

    hep-phPRD(2019)·48 citations
15. 15*

    The molecular nature of some ${\Omega }_c^0$ states

    Gloria Montana🇪🇸 · Angels Ramos🇪🇸 · Albert Feijoo🇨🇿

    A vector meson exchange model based on effective Lagrangians is used to build the meson--baryon interaction in the charm $+1$, strangeness $-2$ and isospin $0$ sector. The s-wave scattering amplitudes resulting from the unitarization in coupled-channels show two resonances with masses and widths that are in very good agreement with those of the experimental ${\Omega }_c(3050{)}^0$ and ${\Omega }_c(3090{)}^0$ states observed by the LHCb collaboration. The interpretation of these resonances as pseudoscalar meson--baryon molecules would mean the assignment $J^P=1/2^{-}$ to their spin--parity.

    hep-phnucl-thSpringer Proc.Phys.(2020)·1 citation
16. 16*

    Quasi equilibrium state of expanding quantum fields and two-pion Bose-Einstein correlations in $pp$ collisions at the LHC

    S.V. Akkelin🇺🇦

    We argue that the two-particle momentum correlation functions of high-multiplicity $p+p$ collisions at the LHC provide a signal for a ground state structure of a quasi equilibrium state of the longitudinally boost-invariant expanding quantum field which lies in the future light cone of a collision. The physical picture is that pions are produced by the expanding quantum emitter with two different scales approximately attributed to the expanding ideal gas in local equilibrium state and ground-state condensate. Specifically, we show that the effect of suppressing the two-particle Bose-Einstein momentum correlation functions increases with increasing transverse momentum of a like-sign pion pair due to different momentum-dependence of the corresponding particle emission regions.

    hep-phhep-exnucl-exnucl-thEPJA(2019)·7 citations
17. 17*

    Non-universal electroweak extensions of the standard model and the scotogenic models

    Dario J. Blandon🇨🇴 · Diego A. Restrepo🇨🇴 · William A. Ponce🇨🇴 · Eduardo Rojas🇨🇴

    In order to analyze some low energy experimental anomalies, we charge with a non-universal $U(1{)}^{\prime }$ gauge symmetry the standard model fermions, taking as a starting point the well-known scotogenic model. In order to have non-trivial solutions to the anomalies and the Yukawa constraints, we add three neutral singlet Dirac fermions. We have found two possible non-universal solutions which, as a matter of principle, are suitable to analyze family-dependent experimental anomalies.

    hep-ph1 citation
18. 18*

    A detailed exploration of the EDGES 21 cm absorption anomaly and axion-induced cooling

    Chuang Li🇨🇳 · Nick Houston🇨🇳 · Tianjun Li🇨🇳 · Qiaoli Yang🇨🇳 · Xin Zhang🇨🇳

    The EDGES collaboration's observation of an anomalously strong 21 cm absorption feature around the cosmic dawn era has energised the cosmological community by suggesting a novel signature of dark matter in the cooling of cosmic hydrogen. In a recent letter we have argued that by virtue of the ability to mediate cooling processes whilst in the condensed phase, a small amount of axion dark matter can explain these observations within the context of standard models of axions and axion-like particles. These axions and axion-like particles (ALPs) can thermalize through gravitational self-interactions and so eventually form a Bose-Einstein condensate (BEC), whereupon large-scale long-range correlation can produce experimentally observable signals such as these. In this context the EDGES best-fit result favours an axion-like-particle mass in the (6, 400) meV range. Future experiments and galaxy surveys, particularly the International Axion Observatory (IAXO) and EUCLID, should have the capability to directly test this scenario. In this paper, we will explore this mechanism in detail and give more thorough computational details of certain key points.

    hep-phastro-ph.COInt.J.Mod.Phys.D(2021)·16 citations
19. 19*

    Computing the gluon Sivers function at small-$x$

    Xiaojun Yao🇺🇸 · Yoshikazu Hagiwara🇯🇵 · Yoshitaka Hatta🇺🇸

    We compute the gluon Sivers function $f_{1T}^{\perp g}(x,k_{\perp })$ of the transversely polarized nucleon at small-$x$ by exploiting the known connection between the dipole gluon Sivers function and the Odderon. We numerically solve the evolution equation for the Odderon both in the linear and nonlinear regimes. While we find that the $x$ and $k_{\perp }$ dependences of the Sivers function do not factorize as a result of the quantum evolution, factorization breaking is not numerically significant, and is much milder than what one expects in the case of unpolarized TMDs. We also point out the possibility that, due to the presence of a node in the Sivers function, single spin asymmetry for open charm production in semi-inclusive deep inelastic scattering flips signs as the transverse momentum of D-mesons is varied. This can be tested at the future Electron-Ion Collider.

    hep-phhep-exnucl-thPLB(2019)·34 citations
20. 20*

    Proton Fixed-Target Scintillation Experiment to Search for Minicharged Particles

    Kevin J. Kelly🇺🇸 · Yu-Dai Tsai🇺🇸

    We propose a low-cost and movable setup to probe minicharged particles (or milli-charged particles) using high-intensity proton fixed-target facilities. This proposal, FerMINI, consists of a milliQan-type detector, requiring multi-coincident (nominally, triple-coincident) scintillation signatures within a small time window, located downstream of the proton target of a neutrino experiment. During the collisions of a large number of protons on the target, intense minicharged particle beams may be produced via meson photo-decays and Drell-Yan production. We take advantage of the high statistics, shielding, and potential neutrino-detector-related background reduction to search for minicharged particles in two potential sites: the MINOS near detector hall and the proposed DUNE near detector hall, both at Fermilab. We also explore several alternative designs, including the modifications of the nominal detector to increase signal yield, and combining this detector technology with existing and planned neutrino detectors to better search for minicharged particles. The CERN SPS beam and associated experimental structure also provide a similar alternative. FerMINI can achieve unprecedented sensitivity for minicharged particles in the MeV to few GeV regime with fractional charge $\epsilon =Q_{\chi }/e$ between $10^{-4}$ (potentially saturating the detector limitation) and $10^{-1}$.

    hep-phhep-exPRD(2019)·90 citations
21. 21*

    Towards a fundamental safe theory of composite Higgs and Dark Matter

    Giacomo Cacciapaglia🇫🇷 · Teng Ma🇨🇳 · Shahram Vatani🇫🇷 · Yongcheng Wu🇨🇦

    We present a novel paradigm that allows to define a composite theory at the electroweak scale that is well defined all the way up to any energy by means of safety in the UV. The theory flows from a complete UV fixed point to an IR fixed point for the strong dynamics (which gives the desired walking) before generating a mass gap at the TeV scale. We discuss two models featuring a composite Higgs, Dark Matter and partial compositeness for all SM fermions. The UV theories can also be embedded in a Pati-Salam partial unification, thus removing the instability generated by the $\text{mbox}U(1)$ running. Finally, we find a Dark Matter candidate still allowed at masses of $260$ GeV, or $1.5\sim 2$ TeV, where the latter mass range will be covered by next generation direct detection experiments.

    hep-phEPJC(2020)·36 citations
22. 22*

    Revisit the $X(4274)$ as the axialvector tetraquark state

    Zhi-Gang Wang🇨🇳

    In this article, we construct the $[sc{]}_A[\bar{s}\bar{c}{]}_V-[sc{]}_V[\bar{s}\bar{c}{]}_A$ type tensor current to study the mass and width of the $X(4274)$ with the QCD sum rules in details. The predicted mass $M_X=(4.27\pm 0.09)\mathrm{GeV}$ for the $J^{PC}=1^{++}$ tetraquark state is in excellent agreement with the experimental data 4273.3 \pm 8.3 ^{+17.2}_{-3.6} \mbox MeV} from the LHCb collaboration. The central value of the width $\Gamma (X(4274)\to J/\psi \varphi )=47.9\mathrm{MeV}$ is in excellent agreement with the experimental data 56 \pm 11 ^{+8}_{-11} \mbox MeV}} from the LHCb collaboration. The present work supports assigning the $X(4274)$ to be the $J^{PC}=1^{++}$ $[sc{]}_A[\bar{s}\bar{c}{]}_V-[sc{]}_V[\bar{s}\bar{c}{]}_A$ tetraquark state with a relative P-wave between the diquark and antidiquark constituents. Furthermore, we obtain the mass of the $[sc{]}_A[\bar{s}\bar{c}{]}_V-[sc{]}_V[\bar{s}\bar{c}{]}_A$ type tetraquark state with $J^{PC}=1^{-+}$ as a byproduct.

    hep-phActa Phys.Polon.B(2020)·20 citations
23. 23*

    Quantum Fine-Tuning in Stringy Quintessence Models

    Mark P. Hertzberg🇺🇸 · McCullen Sandora🇺🇸 · Mark Trodden🇺🇸

    We investigate the extent to which quintessence models for dark energy are fine-tuned in the context of recent swampland conjectures. In particular, the issue is whether there is a double fine-tuning in which both $V$ and $|\nabla V|$ are fine-tuned, or whether there is only a single fine-tuning due to the relation $|\nabla V|\sim V/M_{pl}$ arising naturally. We find that indeed this relation arises naturally in simple string compactifications for some scalars, such as the dilaton and volume modulus, when treated classically. However, we find that quantum effects can spoil this natural relation, unless the scalar is conformally coupled to the matter sector. Furthermore, it is well known that such conformal couplings are generically ruled out by fifth force tests. To avoid these fifth forces, an interesting proposal is to assume the scalar (quintessence) only couples to the hidden sector. However, we then find quantum corrections to $V$ from visible sector Standard Model particles generically spoil the relation. A possible way out of all these problems is to have the scalar conformally coupled to a dark sector that is an exact copy of the Standard Model. This ensures the relation $|\nabla V|\sim V/M_{pl}$ is maintained naturally even when matter particles run in the loop. However, we find that quantum corrections from quintessons or gravitons in the loop spoil the relation if the effective theory has a cutoff greater than $\sim 0.1$ GeV.

    ↳ hep-thastro-ph.COgr-qchep-phPLB(2019)·28 citations
24. 24*

    Screening and enhancement of oscillating electric field in molecules

    H. B. Tran Tan🇦🇺 · V. V. Flambaum🇦🇺 · I. B. Samsonov🇦🇺

    According to the Schiff theorem, the atomic electrons completely screen the atomic nucleus from an external static electric field. However, this is not the case if the field is time-dependent. Electronic orbitals in atoms either shield the nucleus from an oscillating electric field when the frequency of the field is off the atomic resonances or enhance this field when its frequency approaches an atomic transition energy. In molecules, not only electronic, but also rotational and vibrational states are responsible for the screening of oscillating electric fields. As will be shown in this paper, the screening of a low-frequency field inside molecules is much weaker than it appears in atoms owing to the molecular ro-vibrational states. We systematically study the screening of oscillating electric fields inside diatomic molecules in different frequency regimes,i.e., when the field's frequency is either of order of ro-vibrational or electronic transition frequencies. In the resonance case, we demonstrate that the microwave-frequency electric field may be enhanced up to six orders in magnitude due to ro-vibrational states. We also derive the general formulae for the screening and resonance enhancement of oscillating electric field in polyatomic molecules. Possible applications of these results include nuclear electric dipole moment measurements and stimulation of nuclear reactions by laser light.

    ↳ physics.atom-phhep-phquant-phPRA(2019)·11 citations
25. 25*

    HISQ 2+1+1 light quark hadronic vacuum polarization at the physical point

    Christopher Aubin🇺🇸 · Thomas Blum🇺🇸 · Maarten Golterman🇺🇸 · Chulwoo Jung🇺🇸 · Santiago Peris🇪🇸 · Cheng Tu🇺🇸

    We report on the computation of the light quark vacuum polarization with 2+1+1 flavors of H ISQ fermions at the physical point and its contribution to the muon anomalous magnetic moment. Three ensembles, generated by the MILC collaboration, are used to take the continuum limit. We compare our result with recent ones in the literature.

    ↳ hep-lathep-phPoS(2018)·1 citation
26. 26*

    Dispersive Evaluation of the Inner Radiative Correction in Neutron and Nuclear $\beta$-decay

    Chien Yeah Seng🇨🇳 · Mikhail Gorchtein🇩🇪 · Michael J. Ramsey-Musolf🇺🇸

    We propose a novel dispersive treatment of the so-called inner radiative correction to the neutron and nuclear $\beta$-decay. We show that it requires knowledge of the parity-violating structure function $F_3^{(0)}$ that arises from the interference of the axial vector charged current and the isoscalar part of the electromagnetic current. By isospin symmetry, we relate this structure function to the charged current inelastic scattering of neutrinos and antineutrinos. Applying this new data-driven analysis we obtain a new, more precise evaluation for the universal radiative correction ${\Delta }_R^{V,new}=0.02467(22)$ that supersedes the previous estimate by Marciano and Sirlin, ${\Delta }_R^V=0.02361(38)$. The substantial shift in the central value of ${\Delta }_R^V$ reflects in a respective shift of $V_{ud}$ and a considerable tension in the unitarity constraint on the first row of the CKM matrix which is used as one of the most stringent constraints on New Physics contributions in the charged current sector. We also point out that dispersion relations offer a unifying tool for treating hadronic and nuclear corrections within the same framework. We explore the potential of the dispersion relations for addressing the nuclear structure corrections absorbed in the $\mathcal{F}t$ values, a crucial ingredient alongside ${\Delta }_R^V$ in extracting $V_{ud}$ from superallowed nuclear decays.

    ↳ nucl-thhep-phnucl-exPRD(2019)·204 citations
27. 27*

    Zero-mode product expansions and higher order couplings in gauge backgrounds

    Masaki Honda🇯🇵 · Tatsuo Kobayashi🇯🇵 · Hajime Otsuka🇯🇵

    We study a four-dimensional low-energy effective field theory derived from extra dimensional field theories with general gauge backgrounds. We find that products among fermionic zero-modes and lightest scalar modes are expanded by other fermionic zero-modes and lightest scalar modes. Using this aspect, we show that higher-order couplings among the fermionic zero-modes and the lightest scalar mode can be decomposed into three-point couplings. This selection rule originating from a structure of the Dirac-type operators indicates the operator product expansion the underlying conformal field theory.

    ↳ hep-thhep-phPRD(2019)·5 citations
28. 28*

    Cyclotron lines in highly magnetized neutron stars

    R. Staubert🇩🇪 · J. Trümper🇩🇪 · E. Kendziorra🇩🇪 · D. Klochkov🇩🇪 · K. Postnov🇷🇺 · P. Kretschmar🇪🇸 · K. Pottschmidt🇺🇸 · F. Haberl🇩🇪 · R.E. Rothschild🇺🇸 · A. Santangelo🇩🇪 · J. Wilms🇩🇪 · I. Kreykenbohm🇩🇪 · F. Fürst🇪🇸

    Cyclotron lines, also called cyclotron resonant scattering features (CRSF) are spectral features, generally appearing in absorption, in the X-ray spectra of objects containing highly magnetized neutron stars, allowing the direct measurement of the magnetic field strength in these objects. Cyclotron features are thought to be due to resonant scattering of photons by electrons in the strong magnetic fields. The main content of this contribution focusses on electron cyclotron lines as found in accreting X-ray binary pulsars (XRBP) with magnetic fields on the order of several 1012 Gauss. Also, possible proton cyclotron lines from single neutron stars with even stronger magnetic fields are briefly discussed.With regard to electron cyclotron lines, we present an updated list of XRBPs that show evidence of such absorption lines. The first such line was discovered in a 1976 balloon observation of the accreting binary pulsar Hercules X-1, it is considered to be the first direct measurement of the magnetic field of a neutron star. As of today (mid 2018), we list 36 XRBPs showing evidence of one ore more electron cyclotron absorption line(s). A few have been measured only once and must be confirmed (several more objects are listed as candidates). In addition to the Tables of objects, we summarize the evidence of variability of the cyclotron line as a function of various parameters (especially pulse phase, luminosity and time), and add a discussion of the different observed phenomena and associated attempts of theoretical modeling. We also discuss our understanding of the underlying physics of accretion onto highly magnetized neutron stars. For proton cyclotron lines, we present tables with seven neutron stars and discuss their nature and the physics in these objects.

    ↳ astro-ph.HEhep-phAstron.Astrophys.(2019)·237 citations
29. 29*

    Properties of Neutron Stars with hyperon cores in parameterized hydrostatic conditions

    Debashree Sen🇮🇳 · Kinjal Banerjee🇮🇳 · T.K. Jha🇮🇳

    Models of neutron stars (NSs) with hyperon cores are constructed with an effective chiral model in mean-field approximation. The hyperon couplings are fixed by reproducing their experimentally determined binding energies. The impact of these couplings on population of different particles and the equation of state (EoS) are studied in this work. The global properties of NSs like gravitational mass, radius, baryonic mass and central density are calculated using parameterized Tolman-Oppenheimer-Volkoff equations (PTOV) with special emphasis on two effects of pressure - one contributing to total mass density and the other to self gravity of the star. We find that with PTOV solutions in static conditions, a softer EoS (including hyperons) can also lead to massive stellar configurations of NSs, which are in well agreement with the observed maximum mass bound of $\approx 2M_{\odot }$ (PSR J0348-0432). Estimates of $R_{1.4}$ and $R_{1.6}$, obtained with the PTOV equations are consistent with the recent findings of the same from the data analysis of gravitational waves (GW170817) observation. Keywords: Neutron Star; Hyperons; Equation of State; parameterized Tolman-Oppenheimer-Volkoff equations

    ↳ nucl-thastro-ph.HEgr-qchep-phIJMPE(2019)·15 citations
30. 30*

    The hadronic vacuum polarization contribution to $(g-2{)}_{\mu }$ from $2+1$ flavours of O($a$) improved Wilson quarks

    Antoine Gérardin🇩🇪 · Tim Harris🇩🇪 · Georg von Hippel🇩🇪 · Ben Hörz🇩🇪 · Harvey Meyer🇩🇪 · Daniel Mohler🇩🇪 · Konstantin Ottnad🇩🇪 · Hartmut Wittig🇩🇪

    We report on our ongoing project to determine the leading-order hadronic vacuum polarisation contribution to the muon $g-2$, using ensembles with $N_f=2+1$ flavours of O($a$) improved Wilson quarks generated by the CLS effort, with pion masses down to the physical value. We employ O($a$) improved versions of the local and conserved vector currents to compute the contributions of the light, strange and charm quarks to $(g-2{)}_{\mu }$, using the time-momentum representation. We perform a detailed investigation of the systematic effects arising from constraining the long-distance regime of the vector correlator. To this end we make use of auxiliary calculations in the iso-vector channel using distillation and the Lüscher formalism. Our results are corrected for finite-volume effects by computing the timelike pion form factor in finite and infinite volume. For certain parameter choices, the corrections computed in this way can also be confronted with results determined on different volumes. Currently, the overall precision of our results is limited by the uncertainties in the lattice scale.

    ↳ hep-lathep-phPoS(2018)·6 citations
31. 31*

    Massive poles in Lee-Wick quantum field theory

    John F. Donoghue🇺🇸 · Gabriel Menezes🇺🇸

    Most discussions of propagators in Lee-Wick theories focus on the presence of two massive complex conjugate poles in the propagator. We show that there is in fact only one pole near the physical region, or in another representation three pole-like structures with compensating extra poles. The latter modified Lehmann representation is useful caculationally and conceptually only if one includes the resonance structure in the spectral integral.

    ↳ hep-thgr-qchep-phPRD(2019)·28 citations
32. 32*

    Tensor Spectra Templates for Axion-Gauge Fields Dynamics during Inflation

    Tomohiro Fujita🇯🇵 · Evangelos I. Sfakianakis🇳🇱 · Maresuke Shiraishi🇯🇵

    $SU(2)$ gauge fields can generate large gravitational waves during inflation, if they are coupled to an axion which can be either the inflaton or a spectator field. The shape of the produced tensor power spectrum ${\mathcal{P}}_h$ depends on the form of the axion potential. We derive analytic expressions and provide general templates for ${\mathcal{P}}_h$ for various types of the spectator axion potential. Furthermore, we explore the detectability of the oscillatory feature, which is present in ${\mathcal{P}}_h$ in the case of an axion monodromy model, by possible future CMB B-mode polarization observations.

    ↳ astro-ph.COhep-phhep-thJCAP(2019)·30 citations
33. 33*

    Meson-baryon scattering up to the next-to-next-to-leading order in covariant baryon chiral perturbation theory

    Jun-Xu Lu🇨🇳 · Li-Sheng Geng🇨🇳 · Xiu-Lei Ren🇩🇪 · Meng-Lin Du🇩🇪

    We study the scattering of a pseudoscalar meson off one ground state octet baryon in covariant baryon chiral perturbation theory (BChPT) up to the next-to-next-to-leading order. The inherent power counting breaking terms are removed within extended-on-mass-shell scheme. We perform the first combined study of the pion-nucleon and kaon-nucleon scattering data in covariant BChPT and show that it can provide a reasonable description of the experimental data. In addition, we find that it is possible to fit the experimental baryon masses and the pion-nucleon and kaon-nucleon scattering data simultaneously at this order, thus providing a consistent check on covariant BChPT. We compare the scattering lengths of all the pertinent channels with available experimental data and those of other approaches. In addition, we have studied the leading order contributions of the virtual decuplet and found that they can improve the description of the $\pi N$ phase shifts near the $\Delta (1232)$ peak, while they have negligible effects on the description of the $KN$ phase shifts.

    ↳ nucl-thhep-lathep-phPRD(2019)·23 citations
34. 34*

    Probing Leptophilic Dark Sectors at Electron Beam-Dump Facilities

    L. Marsicano🇮🇹 · M. Battaglieri🇮🇹 · A. Celentano🇮🇹 · R. De Vita🇮🇹 · Yi-Ming Zhong🇺🇸

    Medium-energy electron beam-dump experiments provide an intense sources of secondary muons. These particles can be used to search for muon-coupling light dark scalars that may explain the $(g-2{)}_{\mu }$ anomaly. We applied this idea to SLAC E137 experiment deriving new exclusion limits and evaluated the expected sensitivity for the planned Jefferson Lab BDX experiment (in case of null result report). The calculation is based on numerical simulations that include a realistic description of secondary muons generation in the dump, dark scalar production, propagation, and decay, and, finally, the decay products (electrons, positrons, or photons) interaction with the detector. For both experiments, exclusion limits were extended to cover a broader area in the scalar-to-muon coupling vs. scalar mass parameter space. This study demonstrates that electron beam-dump experiments have an enhanced sensitivity to new physics in processes that are usually studied using proton beams.

    ↳ hep-exhep-phPRD(2018)·46 citations
35. 35*

    Two-photon exchange on neutron and the hyperfine splitting

    Oleksandr Tomalak🇩🇪

    We calculate the contribution from the two-photon exchange on the neutron to the hyperfine splitting of S energy levels. We update the value of the neutron Zemach radius, estimate total recoil and polarizability corrections. The resulting two-photon exchange in electronic atoms exceeds by an order of magnitude the leading Zemach term and has different sign both in electronic and muonic hydrogen.

    ↳ nucl-thhep-phnucl-exphysics.atom-phPRD(2019)·12 citations
36. 36*

    Fate of a recent conformal fixed point and $\beta$-function in the SU(3) BSM gauge theory with ten massless flavors

    Zoltan Fodor🇩🇪 · Kieran Holland🇺🇸 · Julius Kuti🇺🇸 · Daniel Nogradi🇭🇺 · Chik Him Wong🇩🇪

    SU(3) gauge theory with $N_f$ fermions in the fundamental representation serves as a theoretical testing ground for possible infrared conformal behavior, which could play a role in BSM composite Higgs models. We use lattice simulations to study the 10-flavor model, for which it has been claimed there is an infrared fixed point in the gauge coupling $\beta$-function. Our results suggest the opposite conclusion, namely we find no $\beta$-function fixed point in the explored range, with qualitative agreement with the 5-loop $\overline{MS}$ prediction. We comment on the inconsistency between our findings and other studies.

    ↳ hep-lathep-phPoS(2018)·16 citations
37. 37*

    Non-local imprints of gravity on quantum theory

    Michael Maziashvili🇬🇪 · Zurab K. Silagadze🇷🇺

    During the last two decades or so much effort has been devoted to the discussion of quantum mechanics (QM) that in some way incorporates the notion of a minimum length. This upsurge of research has been prompted by the modified uncertainty relation brought about in the framework of string theory. In general, the implementation of minimum length in QM can be done either by modification of position and momentum operators or by restriction of their domains. In the former case we have the so called soccer-ball problem when the naive classical limit appears to be drastically different from the usual one. Starting with the latter possibility, an alternative approach was suggested in the form of a band-limited QM. However, applying momentum cutoff to the wave-function, one faces the problem of incompatibility with the Schrödinger equation. One can overcome this problem in a natural fashion by appropriately modifying Schrödinger equation. But incompatibility takes place for boundary conditions as well. Such wave-function cannot have any more a finite support in the coordinate space as it simply follows from the Paley-Wiener theorem. Treating, for instance, the simplest quantum-mechanical problem of a particle in an infinite potential well, one can no longer impose box boundary conditions. In such cases, further modification of the theory is in order. We propose a non-local modification of QM, which has close ties to the band-limited QM, but does not require a hard momentum cutoff. In the framework of this model, one can easily work out the corrections to various processes and discuss further the semi-classical limit of the theory.

    ↳ quant-phhep-phhep-thGen.Rel.Grav.(2021)·2 citations
38. 38*

    Thraxions: Ultralight Throat Axions

    Arthur Hebecker🇩🇪 · Sascha Leonhardt🇩🇪 · Jakob Moritz🇩🇪 · Alexander Westphal🇩🇪

    We argue that a new type of extremely light axion is generically present in the type IIB part of the string theory landscape. Its mass is suppressed by the third power of the warp factor of a strongly warped region (Klebanov-Strassler throat), suggesting the name thraxion. Our observation is based on the generic presence of several throats sharing the same 2-cycle. This cycle shrinks to zero volume at the end of each throat. It is hence trivial in homology and the corresponding $C_2$ axion is massive. However, the mass is warping-suppressed since, if one were to cut off the strongly warped regions, a proper 2-cycle would re-emerge. Since the kinetic term of the axion is dominated in the UV, an even stronger, quadratic mass suppression results. Moreover, if the axion is excited, the angular modes of the throats backreact. This gives our effective $C_2$ axion a finite monodromy and flattens its potential even further. Eventually, the mass turns out to scale as the third power of the warp factor. We briefly discuss possible implications for phenomenology and potential violations of the Weak Gravity Conjecture for axions. Moreover we identify a mechanism for generating super-Planckian axionic field ranges which we call drifting monodromies. However, in the examples we consider, the potential oscillates on sub-Planckian distances in field space, preventing us from building a natural inflation model on the basis of this idea.

    ↳ hep-thgr-qchep-phJHEP(2019)·47 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.