暗物质与标准模型粒子的重力交互研究：发条/线性狄拉顿超维模型

55 浏览量更新于2024-07-16 收藏 1.5MB PDF 举报

"这篇学术论文探讨了暗物质与标准模型粒子在重力介导下的相互作用，特别是在发条/线性狄拉顿超维模型中的情况。研究假设暗物质和标准模型都存在于红外叶（IR-brane）上，并且它们之间的相互作用仅通过 Kaluza-Klein (KK) 引力子和 radion/KK-dilaton 模式进行。作者们详细分析了暗物质的湮灭通道，这些通道涉及标准模型粒子以及KK引力子或KK-dilaton的两层激发态。他们发现，对于5至数百TeV范围的5维重力尺度 M_5，存在一种可能，即通过热冻结机制，可以解释观测到的暗物质丰度，其质量在1至15TeV之间。这个结论对LHC Run II的实验结果具有依赖性，但与暗物质粒子的自旋无关。" 这篇论文详细阐述了暗物质在超弦理论框架中的行为，特别是当暗物质粒子的自旋为0、1/2或1时的情况。在发条/线性狄拉顿模型中，额外维度的概念被引入，这是一个理论物理学中的概念，它试图通过引入额外的空间维度来统一重力与其他基本力。在这个模型中，暗物质和标准模型粒子都被限制在所谓的红外叶（IR-brane）上，这是一种理论构造，用于描述额外维度中的特定区域。论文的关键点在于，暗物质的相互作用不是通过标准模型粒子间的直接交互，而是通过引力的间接作用，即KK引力子和radion/KK-dilaton。KK引力子是普通引力在额外维度的展开形式，而radion/KK-dilaton是与额外维度大小相关的场。作者们分析了暗物质湮灭成标准模型粒子的过程，这个过程涉及到KK激发态的两层，可能是两个KK-gravitons，两个KK-dilatons，或者每种各一个。通过这种分析，研究者找到了一个可能性，即在特定的5维重力尺度下，暗物质的质量可以解释为1至15TeV范围内的值，这与观测到的暗物质丰度相符。这个结论的得出依赖于大型强子对撞机（LHC）Run II的实验数据，表明理论预测与实验结果有潜在的联系，但这个过程与暗物质粒子的自旋性质无关。这篇论文为理解暗物质与标准模型粒子之间的相互作用提供了一个新的视角，同时也为额外维度理论的应用提供了实证依据。通过对KK模式和radion/dilaton的考虑，研究者展示了如何在超弦理论的框架内解释暗物质的一些关键性质，这对于粒子物理学和宇宙学的研究具有重要意义。

JHEP04(2020)036

The action in 5D is:

S = S

gravity

+ S

(2.6)

where the gravitational part is, in the Jordan frame:

gravity

(5)

+ G

(5)

∂

S∂

S + 4k

, (2.7)

with G

(5)

and R

(5)

the 5-dimensional metric and Ricci scalar, respectively, and S the

(dimensionless) dilaton ﬁeld, S = 2kr

|y|. We consider for the two brane actions the

following expressions:

−g

(4)



−f

+ L



(2.8)

and

−g

(4)



−f

+ . . .



, (2.9)

where f

, f

are the brane tensions for the two branes and g

(4)

IR,UV

= −G

(5)

is the

determinant of the induced metric on the IR- and UV-brane, respectively. Throughout

the paper, we consider all the SM and DM ﬁelds localized on the IR-brane, whereas on

the UV-brane we could have any other physics that is Planck-suppressed. We assume that

DM particles only interact with the SM particles gravitationally by considering only DM

singlets under the SM gauge group. More complicated DM spectra with several particles

will also not be studied here.

Notice that the gravitational action is not in its canonical form. Going to the Einstein

frame changing G

(5)

→ exp(−2/3S)G

(5)

, we get:

gravity

−G

(5)





(5)

−

(5)

∂

S∂

S + 4e

−



(2.10)

−g

(4)

−



δ(y − y

)



−f

+ L



− δ(y − π)f



where now the gravitational action is the Einstein action and from the kinetic term of the

dilaton ﬁeld we can read out that the physical ﬁeld must be rescaled as



3/2

√



Eventually, it is important to stress that, in the Einstein frame, the brane action terms

still have an exponential dependence e

−S/3

from the dilaton ﬁeld. This action has a shift

symmetry S → S + const in the limit k → 0, that makes a small value of k with respect

to M

“technically natural” in the ’t Hooft sense. Using the action above in the Einstein

frame, it can be shown that the metric in eq. (2.3) can be recovered as a classical background

if the brane tensions are chosen as:

= −f

= −4k M

. (2.11)

Notice that, in a pure 4-dimensional scenario, the gravitational interactions would be

enormously suppressed by powers of the Planck mass, while in an extra-dimensional one

– 7 –

JHEP04(2020)036

from which it is clear that the coupling between KK-graviton modes with n 6= 0 is sup-

pressed by the eﬀective scale Λ

and not by the Planck scale, diﬀerently from the LED

case and similarly to the Randall-Sundrum one.

It is useful to remind here the explicit form of the energy-momentum tensor for a

scalar, fermion and vector ﬁeld:











µν

= (∂

Φ)

†

(∂

Φ) + (∂

Φ)

†

(∂

Φ) − η

µν

(∂

Φ)

†

(∂ρΦ) − m

ΦΦ

†

µν

= 4



−η

µν



ψ(iγ

∂

− m

)ψ −

∂

(

fiγ





ψiγ

∂

ψ −

∂

(

ψiγ

ψ)

ψiγ

∂

ψ −

∂

(

ψiγ

ψ)



µν



µν



ρσ

−



− F

νρ

+ m



where

µν

= F

µν

= ∂

− ∂

(2.19)

for an abelian gauge ﬁeld and

µν

= F

µν

= ∂

− ∂

+ gf

abc

(2.20)

for a non-abelian gauge ﬁeld. In both cases, the expressions above refers to the unitary

gauge. For the case of the SM massless gauge ﬁelds the expression is T

µν

(whilst we

do not specify how the gauge ﬁeld V

gets a mass).

2.3 Introducing the radion

Stabilization of the radius of the extra-dimension r

is an issue. In general (see, e.g.,

refs. [41–43]), bosonic quantum loops have a net eﬀect on the boundaries of the extra-

dimension such that the extra-dimension itself should shrink to a point. This feature, in a

ﬂat extra-dimension, can only be compensated by fermionic quantum loops and, usually,

some supersymmetric framework is invoked to stabilize the radius of the extra-dimension

(see, e.g., ref. [44]). An additional advantage of supersymmetry in the bulk is that the

CW/LD background metric may protect eq. (2.11) by ﬂuctuations of the 5-dimensional

cosmological constant (see, however, ref. [45] for a non-supersymmetric clockwork imple-

mentation).

In the CW/LD scenario we can use the already present bulk dilaton ﬁeld S to stabilize

the compactiﬁcation radius. If localized brane interactions generate a potential for S at

y = π, then we could ﬁx the value of the ﬁeld S at the UV-brane, S

= S |

. This is

indeed an additional boundary condition that ﬁxes the distance between the two branes to

be πk r

= S

/2 [17]:











−g

(4)

−f

(S − S

)

+ L

−g

(4)

−f

(S − S

)

+ . . .

(2.21)

– 9 –

剩余45页未读，继续阅读

weixin_38682953

粉丝: 7
资源: 986

暗物质与标准模型粒子的重力交互研究：发条/线性狄拉顿超维模型

旋转狄拉顿黑黄铜的热力学与对数非线性电动力学研究

弦论启发下的轴-狄拉顿动力学：解决哈勃张力与早期暗能量

引力彩虹中狄拉顿黑洞的热涨落与相变研究

动态爱因斯坦-狄拉顿模型中全息复杂度的时间依赖性

带电轴和狄拉顿耦合黑洞中的彭罗斯过程

带电零流体来源的爱因斯坦-麦克斯韦-狄拉顿理论中的自相似解和临界行为

轴力-狄拉顿失稳与哈勃张力

爱因斯坦-麦克斯韦-狄拉顿引力的全息复杂性

有限温度下具有狄拉顿场的Randall-Sundrum模型

爱因斯坦-麦克斯韦-狄拉顿理论的渐近结构及其五维起源

最新资源