Wed·Feb 8, 2017Wednesday·February 8, 2017

1. 01*

   A resolution of the inclusive flavor-breaking $\tau$ $|V_{us}|$ puzzle

   Renwick J. Hudspith🇨🇦 · Randy Lewis🇨🇦 · Kim Maltman🇨🇦 · James Zanotti🇦🇺

   We revisit the puzzle of $|V_{us}|$ values obtained from the conventional implementation of hadronic-$\tau$-decay-based flavor-breaking finite-energy sum rules lying $>3\sigma$ below the expectations of three-family unitarity. Significant unphysical dependences of $|V_{us}|$ on the choice of weight, w, and upper limit, $s_0$, of the experimental spectral integrals entering the analysis are confirmed, and a breakdown of assumptions made in estimating higher dimension, $D>4$, OPE contributions is identified as the main source of these problems. A combination of continuum and lattice results is shown to suggest a new implementation of the flavor-breaking sum rule approach in which not only $|V_{us}|$, but also $D>4$ effective condensates, are fit to data. Lattice results are also used to clarify how to reliably treat the slowly converging D=2 OPE series. The new sum rule implementation is shown to cure the problems of the unphysical w- and $s_0$-dependence of $|V_{us}|$ and to produce results $\sim 0.0020$ higher than those of the conventional implementation. With B-factory input, and using, in addition, dispersively constrained results for the $K\pi$ branching fractions, we find $|V_{us}|=0.2231(27{)}_{exp}(4{)}_{th}$, in excellent agreement with the result from $K_{\ell 3}$, and compatible within errors with the expectations of three-family unitarity, thus resolving the long-standing inclusive $\tau$ $|V_{us}|$ puzzle.

   hep-phhep-exhep-latPLB(2018)·46 citations
2. 02*

   Universal descriptions of chemical freeze-out based on pressure and specific heat

   Subhasis Samanta🇮🇳

   The lattice QCD data of pressure and the energy density have been used to extract the hadronic radius parameter of the excluded volume hadron resonance gas (EVHRG) model. The equation of state can be described well with the extracted radius parameter $R_h=0.15$ fm. Specific heat is also calculated in the EVHRG model. Further, two new universal descriptions of chemical freeze-out parameters have been introduced based on pressure and specific heat respectively. It is shown that the chemical freeze-out parameters obtained at various $\sqrt{s_{NN}}$ in ideal HRG model approximately correspond to $P/T^4=0.88$ and $C_V/T^3=47$ respectively. These two quantities are important to describe the thermodynamic properties of the hadronic matter created in heavy ion collision experiment. The sensitivity of universal chemical freeze-out lines on repulsive interaction is also studied. It has been observed that the behaviors of chemical freeze-out lines for $P/T^4$ and $C_V/T^3$ in EVHRG model remain similar to ideal HRG model for the best fit value of hadronic radii.

   hep-phIJMPE(2018)·3 citations
3. 03*

   Naturalness and Dark Matter in the BLSSM

   Luigi Delle Rose🇬🇧 · Shaaban Khalil🇪🇬 · Simon J.D. King🇬🇧 · Carlo Marzo🇪🇪 · Stefano Moretti🇬🇧 · Cem S. Un🇹🇷

   We study the naturalness properties of the $B-L$ Supersymmetric Standard Model (BLSSM) and compare them to those of the Minimal Supersymmetric Standard Model (MSSM) at both low (i.e., Large Hadron Collider) energies and high (i.e., unification) scales. By adopting standard measures of naturalness, we assess that, in presence of full unification of the additional gauge couplings and scalar/fermionic masses of the BLSSM, such a scenario reveals a somewhat higher degree of Fine-Tuning (FT) than the MSSM, when the latter is computed at the unification scale and all available theoretical and experimental constraints, but the Dark Matter (DM) ones, are taken into account. Yet, such a difference, driven primarily by the collider limits requiring a high mass for the gauge boson associated to the breaking of the additional $U(1{)}_{B-L}$ gauge group of the BLSSM in addition to the $SU(3{)}_C\times SU(2{)}_L\times U(1{)}_Y$ of the MSSM, should be regarded as a modest price to pay for the former in relation to the latter, if one notices that the non-minimal scenario offers a significant volume of parameter space where numerous DM solutions of different compositions can be found to the relic density constraints, unlike the case of the minimal structure, wherein only one type of solution is accessible over an ever diminishing parameter space. In fact, this different level of tension within the two SUSY models in complying with current data is well revealed when the FT measure is recomputed in terms of the low energy spectra of the two models, over their allowed regions of parameter space now in presence of all DM bounds, as it is shown that the tendency is now opposite, the BLSSM appearing more natural than the MSSM.

   hep-phPRD(2017)·50 citations
4. 04*

   VBS ${\mathrm{W}}^{\pm }{\mathrm{W}}^{\pm }\mathrm{H}$ production at the HL-LHC and a 100 TeV pp-collider

   Christoph Englert🇬🇧 · Qiang Li🇨🇳 · Michael Spannowsky🇬🇧 · Mengmeng Wang🇨🇳 · Lei Wang🇨🇳

   ${\mathrm{W}}^{\pm }{\mathrm{W}}^{\pm }\mathrm{H}$ production at hadron colliders through vector boson scattering is a so far unconsidered process, which leads to a clean signature of two same-sign charged leptons and two widely separated jets. This process is sensitive to the $\mathrm{HHH}$ and $\mathrm{WWHH}$ couplings and any deviation of these couplings from their SM predictions serves as direct evidence of new physics beyond the SM. In this paper we perform a Monte Carlo study of this process for the $\sqrt{s}=14$ TeV LHC and a $100$ TeV pp-collider, and provide projections of the constraints on the triple-Higgs and $\mathrm{WWHH}$ quartic couplings for these environments. In particular, we consider the impact of pileup on the expected sensitivity in this channel. Our analysis demonstrates that although the sensitivity to the $\mathrm{HHH}$ coupling is rather low, the $\mathrm{WWHH}$ coupling can be constrained in this channel within $\sim 100\%$ and $\sim 20\%$ at 95\% confidence level around the SM prediction at the HL-LHC and a 100 TeV pp-collider, respectively.

   hep-phhep-exInt.J.Mod.Phys.A(2017)·14 citations
5. 05*

   Flavor aspects of parton energy loss

   Martin Spousta🇨🇿

   Understanding flavor dependence of the parton energy loss is one of key tasks of the jet quenching physics. In these proceedings we provide a summary of recent works on a quantification of the flavor dependence of parton energy loss along with a summary and discussion of a subset of contributions presented at the Hard Probes 2016 conference which are related to the flavor aspects of parton energy loss.

   hep-phNucl.Part.Phys.Proc.(2017)·0 citations
6. 06*

   Multiplicity fluctuations near the QCD critical point

   Maurício Hippert🇧🇷 · Eduardo S. Fraga🇧🇷

   Statistical moments of particle multiplicities in heavy-ion collision experiments are an important probe in the exploration of the phase diagram of strongly interacting matter and, particularly, in the search for the QCD critical end point. In order to appropriately interpret experimental measures of these moments, however, it is necessary to understand the role of experimental limitations, as well as background contributions, providing expectations on how critical behavior should be affected by them. We here present a framework for calculating moments of particle multiplicities in the presence of correlations of both critical and spurious origins. We also include effects from resonance decay and a limited acceptance window, as well as detector efficiency. Although we focus on second-order moments, for simplicity, an extension to higher-order moments is straightforward.

   hep-phnucl-thPRD(2017)·16 citations
7. 07*

   QCD leading order study of the $J/\psi$ leptoproduction at HERA within the nonrelativistic QCD framework

   Zhan Sun🇨🇳 · Hong-Fei Zhang🇨🇳

   As indicated in our previous paper (Phys.Rev.D96.034002), the existing literatures studying the $J/\psi$ production in deeply inelastic scattering (DIS) in collinear factorization are on the basis of a formalism that will lead to wrong results when the ranges of the transverse momentum or the rapidity of the $J/\psi$ in the laboratory frame do not cover all values possible for them. In this paper, we present the renewed results for the $J/\psi$ production in DIS at HERA within the nonrelativistic QCD framework at QCD leading order (LO). Three different sets of the long-distance matrix elements are employed for comparison. The predictions via the colour-singlet (CS) model at QCD LO are generally below the experimental data especially in the regions where perturbation theory are expected to work well, while the colour-octet contributions are of the same order of magnitude as the CS ones, however, in general make the agreement between theory and experiment better.

   hep-phhep-exEPJC(2017)·22 citations
8. 08*

   Diffractive scattering on the deuteron

   M.A.Braun🇷🇺

   High-mass diffractive production of protons on the deuteron target is studied in the perturbative QCD in the BFKL approach. Leading order rearrangement contribution and the standard triple pomeron (the impulse approximation) are studied. In the perturbative limit ${\alpha }_s\to 0$ the rearrangement contribution dominates. Numerical estimates at realistic values of ${\alpha }_s$ and energies strongly depend on assumptions made about the behavior of the pomeron attached to the proton due to unitarization. They indicate that irrespective of these assumptions in the realistic situation the rearrangement and triple pomeron contributions turn out to be of comparable magnitude due to large dimensions of the deuteron.

   hep-phEPJC(2017)·12 citations
9. 09*

   Resonant slepton production and right sneutrino dark matter in left-right supersymmetry

   Mariana Frank🇨🇦 · Benjamin Fuks🇫🇷 · Katri Huitu🇫🇮 · Santosh Kumar Rai🇮🇳 · Harri Waltari🇫🇮

   Right-handed sneutrinos are natural components of left-right symmetric supersymmetric models where the gauge sector is extended to include right-handed weak interactions. Unlike in other models where right-handed sneutrinos are gauge singlets, here the right sneutrino is part of a doublet and could be a dark matter candidate whose annihilation proceeds via gauge interactions. We investigate this possibility, and find that relic density, low-energy observable and direct supersymmetry search constraints can be satisfied when the lightest supersymmetric particle is a right-handed sneutrino. We introduce benchmarks for left-right supersymmetric realizations where either a sneutrino or a neutralino is the lightest superpartner. We then study the LHC signals arising through resonant right-handed slepton production via a $W_R$ gauge-boson exchange that lead to final states enriched in leptons, additionally containing a large amount of missing transverse momentum, and featuring a low jet multiplicity. We find that such a resonant production would boost the chances of discovering these weakly interacting supersymmetric particles for a mass range extending beyond 1 TeV already with a luminosity of 100 fb${}^{-1}$. Finally, we compare sneutrino versus neutralino scenarios, and comment on differences with other sneutrino dark matter models.

   hep-phJHEP(2017)·18 citations
10. 10*

    Cosmological production of ultralight dark matter axions

    Alberto Diez-Tejedor🇲🇽 · David J. E. Marsh🇬🇧

    The highly populated, low-energy excitations of a scalar field of mass $m_a\sim 10^{-22}\text{eV}$ can represent the full dark matter content of the universe and alleviate some tensions in the standard cosmological scenario on small-scales. This {\it fuzzy dark matter} component is commonly assumed to arise as the consequence of a new axion-like particle in the matter sector, yet for simplicity it is usually modeled in terms of a simple free quadratic field. In this paper we consider how the cosmological constraints are modified when the effects of an instanton potential and temperature-dependent mass are included. Current isocurvature and tensor bounds confirms that this particle should be formed before the end of a low-scale inflation period with Hubble parameter $H_I\lesssim 2.5\times 10^{12}\text{GeV}$, in accordance with previous free-field analysis. The axion decay constant, $f_a$, which fixes axion couplings, appears in the instanton potential and determines the relic abundance, the stability of galaxy cores to axion emission, and the direct searches of fuzzy dark matter. If the axion mass is $T$-independent, we find that $f_a\gtrsim 10^{16}\text{GeV}$ is required in order to reach the observed relic density without fine tuning the initial conditions, while for a $T$-dependent case this bound can be lowered by an order of magnitude. However, the anharmonicities in the instanton potential, and mainly a $T$-dependent mass, can delay the onset of field oscillations, leading to larger physical suppression scales in the matter power spectrum for a fixed zero-temperature axion mass. This may favor a string or accidental axion over one emerging from a strongly coupled gauge sector if this model is required to provide large galactic halo cores while simultaneously satisfying observational constraints from cosmic structure formation.

    hep-phastro-ph.COgr-qchep-th52 citations
11. 11*

    Gravitational waves from the asymmetric-dark-matter generating phase transition

    Iason Baldes🇩🇪

    The baryon asymmetry, together with a dark matter asymmetry, may be produced during a first order phase transition in a generative sector. We study the possibility of a gravitational wave signal in a model realising such a scenario. We identify areas of parameter space with strong phase transitions which can be probed by future, space based, gravitational wave detectors. Other signals of this scenario include collider signatures of a $Z^{\prime }$, DM self interactions, a contribution to $\Delta N_{\mathrm{eff}}$ and nuclear recoils at direct detection experiments.

    hep-phJCAP(2017)·92 citations
12. 12*

    R-axion at colliders

    Brando Bellazzini🇫🇷 · Alberto Mariotti🇧🇪 · Diego Redigolo🇮🇱 · Filippo Sala🇫🇷 · Javi Serra🇨🇭

    We study the effective theory of a generic class of hidden sectors where supersymmetry is broken together with an approximate R-symmetry at low energy. The light spectrum contains the gravitino and the pseudo-Nambu-Goldstone boson of the R-symmetry, the R-axion. We derive new model-independent constraints on the R-axion decay constant for R-axion masses ranging from GeV to TeV, which are of relevance for hadron colliders, lepton colliders and B-factories. The current bounds allow for the exciting possibility that the first sign of SUSY will be the R-axion. We point out its most distinctive signals, providing a new experimental handle on the properties of the hidden sector and a solid motivation for searches of axion-like particles.

    hep-phhep-exhep-thPRL(2017)·94 citations
13. 13*

    Lepton asymmetry rate from quantum field theory: NLO in the hierarchical limit

    Dietrich Bodeker🇩🇪 · Marc Sangel🇩🇪

    The rates for generating a matter-antimatter asymmetry in extensions of the Standard Model (SM) containing right-handed neutrinos are the most interesting and least trivial coefficients in the rate equations for baryogenesis through thermal leptogenesis. We obtain a relation of these rates to finite-temperature real-time correlation functions, similar to the Kubo formulas for transport coefficients. Then we consider the case of hierarchical masses for the sterile neutrinos. At leading order in their Yukawa couplings we find a simple master formula which relates the rates to a single finite temperature three-point spectral function. It is valid to all orders in $g$,where $g$ denotes a SM gauge or quark Yukawa coupling. We use it to compute the rate for generating a matter-antimatter asymmetry at next-to-leading order in g in the non-relativistic regime. The corrections are of order $g^2$, and they amount to 4% or less.

    hep-phJCAP(2017)·21 citations
14. 14*

    Antinucleon-nucleon interaction at next-to-next-to-next-to-leading order in chiral effective field theory

    Ling-Yun Dai🇩🇪 · Johann Haidenbauer🇩🇪 · Ulf-G. Meißner🇩🇪

    Results for the antinucleon-nucleon ($\bar{N}N$) interaction obtained at next-to-next-to-next-to-leading order in chiral effective field theory (EFT) are reported. A new local regularization scheme is used for the pion-exchange contributions that has been recently suggested and applied in a pertinent study of the $NN$ force within chiral EFT. Furthermore, an alternative strategy for estimating the uncertainty is utilized that no longer depends on a variation of the cutoffs. The low-energy constants associated with the arising contact terms are fixed by a fit to the phase shifts and inelasticities provided by a phase-shift analysis of $\bar{p}p$ scattering data. An excellent description of the $\bar{N}N$ amplitudes is achieved at the highest order considered. Moreover, because of the quantitative reproduction of partial waves up to $J=3$, there is also a nice agreement on the level of $\bar{p}p$ observables. Specifically, total and integrated elastic and charge-exchange cross sections agree well with the results from the partial-wave analysis up to laboratory energies of $300$ MeV, while differential cross sections and analyzing powers are described quantitatively up to $200$-$250$ MeV. The low-energy structure of the $\bar{N}N$ amplitudes is also considered and compared to data from antiprotonic hydrogen.

    ↳ nucl-thhep-phJHEP(2017)·70 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.