Thu·May 23, 2019Thursday·May 23, 2019

1. 01*

   An Emergent Solution to the Strong CP Problem

   Jason Arakawa🇺🇸 · Arvind Rajaraman🇺🇸 · Tim M.P. Tait🇺🇸

   We construct a theory in which the solution to the strong CP problem is an emergent property of the background of the dark matter in the Universe. The role of the axion degree of freedom is played by multi-body collective excitations similar to spin-waves in the medium of the dark matter of the Galactic halo. The dark matter is a vector particle whose low energy interactions with the Standard Model take the form of its spin density coupled to $G\tilde{G}$, which induces a potential on the average spin density inducing it to compensate $\overline{\theta }$, effectively removing CP violation in the strong sector in regions of the Universe with sufficient dark matter density. We discuss the viable parameter space, finding that light dark matter masses within a few orders of magnitude of the fuzzy limit are preferred, and discuss the associated signals with this type of solution to the strong CP problem.

   hep-phhep-thPRL(2019)·4 citations
2. 02*

   Kaon form factor in holographic QCD

   Zainul Abidin🇮🇩 · Parada T. P. Hutauruk🇰🇷

   The kaon form factor in the spacelike region is calculated using a holographic QCD model with the "bottom-up" approach. We found that our result for the kaon form factor in low $Q^2$ has a remarkable agreement with the existing data, where $Q^2$ is the four-momentum transfer squared. The charge radius of the kaon, as well as the kaon decay constant, are found to be in a good agreement with the experiment data. We then predict the kaon form factor in the asymptotic region (larger $Q^2$) showing $1/Q^2$ behavior, which is consistent with the perturbative QCD prediction.

   hep-phnucl-thPRD(2019)·18 citations
3. 03*

   Wave Packets Losing Their Covariance

   Emilio Ciuffoli🇨🇳 · Jarah Evslin🇨🇳 · Hosam Mohammed🇨🇳

   In neutrino physics, it is sometimes assumed that all wave packets must transform covariantly as Lorentz vectors. We show in a simple example that even if the initial conditions of a wave packet are covariant, then evolution in a relativistic interacting theory followed by a measurement of entangled particles can lead to a wave packet which is no longer covariant.

   hep-phNPB(2020)·3 citations
4. 04*

   Triple Differential Dijet Cross Section at the LHC

   Aude Gehrmann-De Ridder🇨🇭 · Thomas Gehrmann🇨🇭 · E.W.N. Glover🇬🇧 · Alexander Huss🇨🇭 · Joao Pires🇵🇹

   The measurement of the triple-differential dijet production cross section as a function of the average transverse momentum $p_{T,\text{avg}}$, half the rapidity separation $y^{\ast }$, and the boost $y_b$ of the two leading jets in the event enables a kinematical scan of the underlying parton momentum distributions. We compute for the first time the second-order perturbative QCD corrections to this triple-differential dijet cross section, at leading color in all partonic channels, thereby enabling precision studies with LHC dijet data. A detailed comparison with experimental CMS 8 TeV data is performed, demonstrating how the shape of this differential cross section probes the parton densities in different kinematical ranges.

   hep-phPRL(2019)·54 citations
5. 05*

   Event Generation with Sherpa 2.2

   Enrico Bothmann🇩🇪 · Gurpreet Singh Chahal🇬🇧 · Stefan Höche🇺🇸 · Johannes Krause🇩🇪 · Frank Krauss🇬🇧 · Silvan Kuttimalai🇺🇸 · Sebastian Liebschner🇩🇪 · Davide Napoletano🇫🇷 · Marek Schönherr🇬🇧 · Holger Schulz🇺🇸 · Steffen Schumann🇩🇪 · Frank Siegert🇩🇪

   Sherpa is a general-purpose Monte Carlo event generator for the simulation of particle collisions in high-energy collider experiments. We summarize essential features and improvements of the Sherpa 2.2 release series, which is heavily used for event generation in the analysis and interpretation of LHC Run 1 and Run 2 data. We highlight a decade of developments towards ever higher precision in the simulation of particle-collision events.

   hep-phhep-exSciPost Phys.(2019)·1575 citations
6. 06*

   A Note on Gravitational Particle Production in Supergravity

   Kazunori Nakayama🇯🇵

   It is pointed out that the gravitational particle production rate of a scalar component of a chiral superfield in supergravity with minimal Kahler potential can be significantly suppressed compared with a minimal scalar field in non-supersymmetric Einstein gravity. This suppression is avoided for some choice of the inflaton sector and also for non-minimal Kahler potential of the chiral superfield.

   hep-phastro-ph.COPLB(2019)·5 citations
7. 07*

   Conformal invariance of TMD rapidity evolution

   Ian Balitsky🇺🇸 · Giovanni A. Chirilli🇩🇪

   We discuss conformal properties of TMD operators and present the result of the conformal rapidity evolution of TMD operators in the Sudakov region.

   hep-phhep-thPRD(2019)·20 citations
8. 08*

   The NLO fragmentation functions of heavy quarks into heavy quarkonia

   Xu-Chang Zheng🇨🇳 · Chao-Hsi Chang🇨🇳 · Xing-Gang Wu🇨🇳

   In the paper, we derive the next-to-leading order (NLO) fragmentation function for a heavy quark, either charm or bottom, into a heavy quarkonium $J/\Psi$ or ${\rm Y}$. The ultra-violet divergences in the real corrections are removed through the operator renormalization, which is performed under the modified minimal subtraction scheme. We then obtain the NLO fragmentation function at an initial factorization scale, e.g. ${\mu }_F=3m_c$ for $c\to J/\Psi$ and ${\mu }_F=3m_b$ for $b\to {\rm Y}$, which can be evolved to any scale via the use of Dokshitzer-Gribov-Lipatov-Altarelli-Parisi equation. As an initial application of those fragmentation functions, we study the $J/\Psi$ (${\rm Y}$) production at a high luminosity $e^{+}{e}^{-}$ collider which runs at the energy around the $Z$ pole and could be a suitable platform for testing the fragmentation function.

   hep-phPRD(2019)·49 citations
9. 09*

   Effective Field Theory Treatment of Monopole Production by Drell-Yan and Photon Fusion for Various Spins

   Stephanie Baines🇬🇧

   A resolution over the existence of magnetic charges has eluded the high energy physics community for centuries, and their search has gained momentum as recent models predict these may be observable at current colliders. They appear in field theories in two forms: the widely studied but heavily suppressed monopole with structure (soliton) and the not-so-well-covered point-like monopole. The latter was first proposed by Dirac as the source of a singular magnetic field and in effect symmetrises Maxwell's equations. Following this line of research, work by S. Baines et al. analysed these sources as matter fields that carry spins 0, $\frac{1}{2}$, or 1, in an effective field theory that is perturbative for monopoles produced at threshold where the coupling strength $g(\beta )$ is suppressed. All three cases are currently under investigation by the MoEDAL collaboration at CERN, and the theoretical expressions for kinematic distributions proposed in this work serve as guides to these searches. The cross section distributions in each case are derived from a \emph{U}(1) invariant gauge theory. It is not assumed that, like the electron, the monopole's magnetic moment is generated through spin interactions at minimal coupling, as it may be quite large. Instead, the analytical expressions in the spin $\frac{1}{2}$ and $1$ cases are kept completely general through the inclusion of a phenomenological parameter $\kappa$, related to the gyromagnetic ratio $g_R=1+\kappa$. In fact, the inclusion of this parameter gives the effective theory validity in the high energy limit if the magnetic coupling scales with the particle's velocity $\beta =\frac{v}{c}$.

   hep-phMDPI Proc.(2019)·3 citations
10. 10*

    Spatial interpretation of "compositeness" for finite-range potentials

    Peter C. Bruns🇨🇿

    We discuss the relation between the "compositeness" of an s-wave bound state, as derived from a related partial wave scattering amplitude, and the corresponding spatial probability densities, for the case of spherically symmetric, energy-independent finite-range potentials in non-relativistic quantum mechanics. We find that in this simple case "compositeness" is a measure for the probability to find the constituents separated by a distance greater than the interaction range.

    hep-ph12 citations
11. 11*

    Lowest order QED radiative effects in polarized SIDIS

    Igor Akushevich🇺🇸 · Alexander Ilyichev🇧🇾

    The explicit exact analytical expressions for the lowest-order radiative corrections to the semi-inclusive deep inelastic scattering of the polarized particles are obtained in the most compact, covariant form convenient for the numerical analysis. The infrared divergence from the real photon emission is extracted and cancelled using the Bardin-Shumeiko approach. The contribution of the exclusive radiative tail is presented.The analytic results obtained within the ultrarelativistic approximation are also show.

    hep-phPRD(2019)·13 citations
12. 12*

    Limits on $R$-parity Violation in High Scale Supersymmetry

    Emilian Dudas🇫🇷 · Tony Gherghetta🇺🇸 · Kunio Kaneta🇺🇸 · Yann Mambrini🇫🇷 · Keith A. Olive🇺🇸

    We revisit the limits on $R$-parity violation in the minimal supersymmetric standard model. In particular, we focus on the high-scale supersymmetry scenario in which all the sparticles are in excess of the inflationary scale of approximately $10^{13}$ GeV, and thus no sparticles ever come into thermal equilibrium. In this case the cosmological limits, stemming from the preservation of the baryon asymmetry that have been previously applied for weak scale supersymmetry, are now relaxed. We argue that even when sparticles are never in equilibrium, $R$-parity violation is still constrained via higher dimensional operators by neutrino and nucleon experiments and/or insisting on the preservation of a non-zero $B-L$ asymmetry.

    hep-phPRD(2019)·10 citations
13. 13*

    Layers of quark-gluon plasma induced by chiral magnetic effect and the separation of $u,d$ quarks' critical end points

    Bin Wang🇨🇳

    In this work we show that the chiral magnetic effect (CME) could cause the quark-gluon plasma (QGP) approximately forming three layers along the strong magnetic field characterised by different compositions of quark chemical potentials. This phenomenon may bring new observable outcomes, for example different layers would have different CEPs and the $u,d$ quarks would have different critical end points (CEPs). Since the $s$ quark would make the up and the down layers have some 'asymmetry' on chemical potentials, there is the possibility that at some special conditions one flavor of $u,d$ quarks lies at CEP in one layer but another flavor dose not in any layer. These results may be helpful in testing the existence of CME.

    hep-ph0 citations
14. 14*

    Pre-Supernova Neutrinos in Large Dark Matter Direct Detection Experiments

    Nirmal Raj🇨🇦 · Volodymyr Takhistov🇺🇸 · Samuel J. Witte🇪🇸

    The next Galactic core-collapse supernova (SN) is a highly anticipated observational target for neutrino telescopes. However, even prior to collapse, massive dying stars shine copiously in "pre-supernova" (pre-SN) neutrinos, which can potentially act as efficient SN warning alarms and provide novel information about the very last stages of stellar evolution. We explore the sensitivity to pre-SN neutrinos of large scale direct dark matter detection experiments, which, unlike dedicated neutrino telescopes, take full advantage of coherent neutrino-nucleus scattering. We find that argon-based detectors with target masses of $\mathcal{O}(100)$ tonnes (i.e. comparable in size to the proposed ARGO experiment) operating at sub-keV thresholds can detect $\mathcal{O}(10-100)$ pre-SN neutrinos coming from a source at a characteristic distance of $\sim$200 pc, such as Betelgeuse ($\alpha$ Orionis). Large-scale xenon-based experiments with similarly low thresholds could also be sensitive to pre-SN neutrinos. For a Betelgeuse-type source, large scale dark matter experiments could provide a SN warning siren $\sim$10 hours prior to the explosion. We also comment on the complementarity of large scale direct dark matter detection experiments and neutrino telescopes in the understanding of core-collapse SN.

    hep-phastro-ph.HEhep-exPRD(2020)·43 citations
15. 15*

    Supernova signals of light dark matter

    William DeRocco🇺🇸 · Peter W. Graham🇺🇸 · Daniel Kasen🇺🇸 · Gustavo Marques-Tavares🇺🇸 · Surjeet Rajendran🇺🇸

    Dark matter direct detection experiments have poor sensitivity to a galactic population of dark matter with mass below the GeV scale. However, such dark matter can be produced copiously in supernovae. Since this thermally-produced population is much hotter than the galactic dark matter, it can be observed with direct detection experiments. In this paper, we focus on a dark sector with fermion dark matter and a heavy dark photon as a specific example. We first extend existing supernova cooling constraints on this model to the regime of strong coupling where the dark matter becomes diffusively trapped in the supernova. Then, using the fact that even outside these cooling constraints the diffuse galactic flux of these dark sector particles can still be large, we show that this flux is detectable in direct detection experiments such as current and next-generation liquid xenon detectors. As a result, due to supernova production, light dark matter has the potential to be discovered over many orders of magnitude of mass and coupling.

    hep-phastro-ph.HEPRD(2019)·72 citations
16. 16*

    Dynamical Friction in Superfluids

    Lasha Berezhiani🇩🇪 · Benjamin Elder🇬🇧 · Justin Khoury🇺🇸

    We compute the dynamical friction on a small perturber moving through an inviscid fluid, i.e., a superfluid. Crucially, we account for the tachyonic gravitational mass for sound waves, reminiscent of the Jeans instability of the fluid, which results in non-zero dynamical friction even for subsonic velocities. Moreover, we illustrate that the standard leading order effective theory in the derivative expansion is in general inadequate for analysing supersonic processes. We show this in two ways: (i) with a fluid treatment, where we solve the linearized hydrodynamical equations coupled to Newtonian gravity; and (ii) with a quasiparticle description, where we study the energy dissipation of a moving perturber due to phonon radiation. Ordinarily a subsonic perturber moving through a superfluid is kinematically prohibited from losing energy, however the Jeans instability modifies the dispersion relation of the fluid which can result in a small but non-vanishing dynamical friction force. We also analyse the soft phonon bremsstrahlung by a subsonic perturber scattered off an external field.

    hep-phastro-ph.GAgr-qchep-thJCAP(2019)·48 citations
17. 17*

    Hadronization and Charm-Hadron Ratios in Heavy-Ion Collisions

    Min He🇨🇳 · Ralf Rapp🇺🇸

    Understanding the hadronization of the quark-gluon plasma (QGP) remains a challenging problem in the study of strong-interaction matter as produced in ultrarelativistic heavy-ion collisions (URHICs). The large mass of heavy quarks renders them excellent tracers of the color neutralization process of the QGP when they convert into various heavy-flavor (HF) hadrons. We develop a 4-momentum conserving recombination model for HF mesons and baryons that recovers the thermal and chemical equilibrium limits and accounts for space-momentum correlations (SMCs) of heavy quarks with partons of the hydrodynamically expanding QGP, thereby resolving a long-standing problem in quark coalescence models. The SMCs enhance the recombination of fast-moving heavy quarks with high-flow thermal quarks in the outer regions of the fireball. We also improve the hadro-chemistry with "missing" charm-baryon states, previously found to describe the large ${\Lambda }_c/D^0$ ratio observed in proton-proton collisions. Both SMCs and hadro-chemistry, as part of our HF hydro-Langevin-recombination model for the strongly coupled QGP, importantly figure in the description of recent data for the ${\Lambda }_c/D^0$ ratio and $D$-meson elliptic flow in URHICs.

    ↳ nucl-thhep-phnucl-exPRL(2020)·179 citations
18. 18*

    Analytic Transport from Weak to Strong Coupling in the O(N) model

    Paul Romatschke🇺🇸

    In this work, a second-order transport coefficient (the curvature-matter coupling $\kappa$) is calculated exactly for the 3+1d O(N) model at large N for any coupling value. Since the theory is `trivial' in the sense of possessing a Landau pole, the result for $\kappa$ only is free from cut-off artifacts much below the Landau pole in the effective field theory sense. Nevertheless, this leaves a large range of coupling values where this transport coefficient can be determined non-perturbatively and analytically with little ambiguity. Along with thermodyamic results also calculated in this work, I expect exact large N results to provide good quantitative predictions for N=1 scalar field theory with ${\varphi }^4$ interaction.

    ↳ hep-thcond-mat.str-elhep-phnucl-thPRD(2019)·19 citations
19. 19*

    Constraint on the solar $\Delta m^2$ using 4,000 days of short baseline reactor neutrino data

    Alvaro Hernandez Cabezudo🇩🇪 · Stephen J. Parke🇺🇸 · Seon-Hee Seo🇰🇷

    There is a well known 2$\sigma$ tension in the measurements of the solar $\Delta m^2$ between KamLAND and SNO/Super-KamioKANDE. Precise determination of the solar $\Delta m^2$ is especially important in connection with current and future long baseline CP violation measurements. Reference \cite{Seo:2018rrb} points out that currently running short baseline reactor neutrino experiments, Daya Bay and RENO, can also constrain solar $\Delta m^2$ value as demonstrated by a GLoBES simulation with a limited systematic uncertainty consideration. In this work, the publicly available data, from Daya Bay (1,958 days) and RENO (2,200 days) are used to constrain the solar $\Delta m^2$. Verification of our method through $\Delta m_{ee}^2$ and ${\sin }^2{\theta }_{13}$ measurements is discussed in Appendix A. Using this verified method, reasonable constraints on the solar $\Delta m^2$ are obtained using above Daya Bay and RENO data, both individually and combined. We find that the combined data of Daya Bay and RENO set an upper limit on the solar $\Delta m^2$ of 18 $\times 10^{-5}$ eV${}^2$ at the 95% C.L., including both systematic and statistical uncertainties. This constraint is slightly more than twice the KamLAND value. As this combined result is still statistics limited, even though driven by Daya Bay data, the constraint will improve with the additional running of this experiment.

    ↳ hep-exhep-phPRD(2019)·8 citations
20. 20*

    Kramers's escape rate problem within a non-Markovian description

    Benjamin Schüller🇩🇪 · Alex Meistrenko🇩🇪 · Hendrik van Hees🇩🇪 · Zhe Xu🇨🇳 · Carsten Greiner🇩🇪

    We compare the thermal escape rates of a Brownian particle, initially trapped into one of the two wells of an asymmetric double-well potential, for thermal Markovian and non-Markovian noise. The Markovian treatment of this problem goes originally back to the studies of Kramers in 1940 and is therefore often referred to as "Kramers's escape rate problem". We solve the generalized Langevin equation for the trajectories of the particles numerically and analytically for both limiting cases, Markovian and non-Markovian thermal noise. We compute the escape rate and work out the fundamental differences arising from finite correlation times of the thermal noise.

    ↳ cond-mat.stat-mechhep-phnucl-thAnnals Phys.(2020)·7 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.