[u/mrichter/AliRoot.git] / PYTHIA8 / pythia8130 / xmldoc / ExtraDimensionalProcesses.xml

<chapter name="Extra-Dimensional Processes">

<h2>Extra-Dimensional Processes</h2>

Scenarios with extra dimensions allow a multitude of processes.
Currently the only ones implemented involve the production of an 
excited graviton state <ei>G^*</ei> within a Randall-Sundrum scenario.
This state is assigned PDG code 5000039. Decays into fermion, gluon
and photon pairs are handled with the correct angular distributions,
while other decay channels currently are handled isotropically.

<h3>Production processes</h3>

There are two lowest-order processes that together normally should be 
sufficient for a simulation of <ei>G^*</ei> production. 

<flag name="ExtraDimensionsG*:all" default="off">
Common switch for the group of lowest-order <ei>G^*</ei> production
processes, i.e. the two ones below.
</flag>

<flag name="ExtraDimensionsG*:gg2G*" default="off">
Scatterings <ei>g g -> G^*</ei>. 
Code 5001.
</flag>

<flag name="ExtraDimensionsG*:ffbar2G*" default="off">
Scatterings <ei>f fbar -> G^*</ei>. 
Code 5002.
</flag>

<p/>
In addition there are three first-order processes included. These are of
less interest, but can be used for dedicated studies of the high-<ei>pT</ei> 
tail of <ei>G^*</ei> producton. As usual, it would be doublecounting to
include the lowest-order and first-order processes simultaneously.
Therefore the latter ones are not included with the 
<code>ExtraDimensionsG*:all = on</code> option. In this set of processes
all decay angles are assumed istropic.

<flag name="ExtraDimensionsG*:gg2G*g" default="off">
Scatterings <ei>g g -> G^* g</ei>. 
Code 5003.
</flag>

<flag name="ExtraDimensionsG*:qg2G*q" default="off">
Scatterings <ei>q g -> G^* q</ei>. 
Code 5004.
</flag>

<flag name="ExtraDimensionsG*:qqbar2G*g" default="off">
Scatterings <ei>q qbar -> G^* g</ei>. 
Code 5005.
</flag>


<h3>Parameters</h3>

In the above scenario the main free parameter is the <ei>G^*</ei> mass,
which is set as usual. In addition there is one further parameter.

<parm name="ExtraDimensionsG*:kappaMG" default="0.054" min="0.0">
dimensionless coupling, which enters quadratically in all partial
widths of the <ei>G^*</ei>. Is 
<ei>kappa m_G* = sqrt(2) x_1 k / Mbar_Pl</ei>,
where <ei>x_1 = 3.83</ei> is the first zero of the <ei>J_1</ei> Bessel 
function and <ei>Mbar_Pl</ei> is the modified Planck mass.
</parm>

</chapter>

<!-- Copyright (C) 2008 Torbjorn Sjostrand -->
Commit	Line	Data
5ad4eb21	1	<chapter name="Extra-Dimensional Processes">
	2
	3	<h2>Extra-Dimensional Processes</h2>
	4
	5	Scenarios with extra dimensions allow a multitude of processes.
	6	Currently the only ones implemented involve the production of an
	7	excited graviton state <ei>G^*</ei> within a Randall-Sundrum scenario.
	8	This state is assigned PDG code 5000039. Decays into fermion, gluon
	9	and photon pairs are handled with the correct angular distributions,
	10	while other decay channels currently are handled isotropically.
	11
	12	<h3>Production processes</h3>
	13
	14	There are two lowest-order processes that together normally should be
	15	sufficient for a simulation of <ei>G^*</ei> production.
	16
	17	<flag name="ExtraDimensionsG*:all" default="off">
	18	Common switch for the group of lowest-order <ei>G^*</ei> production
	19	processes, i.e. the two ones below.
	20	</flag>
	21
	22	<flag name="ExtraDimensionsG:gg2G" default="off">
	23	Scatterings <ei>g g -> G^*</ei>.
	24	Code 5001.
	25	</flag>
	26
	27	<flag name="ExtraDimensionsG:ffbar2G" default="off">
	28	Scatterings <ei>f fbar -> G^*</ei>.
	29	Code 5002.
	30	</flag>
	31
	32	<p/>
	33	In addition there are three first-order processes included. These are of
	34	less interest, but can be used for dedicated studies of the high-<ei>pT</ei>
	35	tail of <ei>G^*</ei> producton. As usual, it would be doublecounting to
	36	include the lowest-order and first-order processes simultaneously.
	37	Therefore the latter ones are not included with the
	38	<code>ExtraDimensionsG*:all = on</code> option. In this set of processes
	39	all decay angles are assumed istropic.
	40
	41	<flag name="ExtraDimensionsG:gg2Gg" default="off">
	42	Scatterings <ei>g g -> G^* g</ei>.
	43	Code 5003.
	44	</flag>
	45
	46	<flag name="ExtraDimensionsG:qg2Gq" default="off">
	47	Scatterings <ei>q g -> G^* q</ei>.
	48	Code 5004.
	49	</flag>
	50
	51	<flag name="ExtraDimensionsG:qqbar2Gg" default="off">
	52	Scatterings <ei>q qbar -> G^* g</ei>.
	53	Code 5005.
	54	</flag>
	55
	56
	57	<h3>Parameters</h3>
	58
	59	In the above scenario the main free parameter is the <ei>G^*</ei> mass,
	60	which is set as usual. In addition there is one further parameter.
	61
	62	<parm name="ExtraDimensionsG*:kappaMG" default="0.054" min="0.0">
	63	dimensionless coupling, which enters quadratically in all partial
	64	widths of the <ei>G^*</ei>. Is
65	<ei>kappa m_G* = sqrt(2) x_1 k / Mbar_Pl</ei>,
66	where <ei>x_1 = 3.83</ei> is the first zero of the <ei>J_1</ei> Bessel
67	function and <ei>Mbar_Pl</ei> is the modified Planck mass.
68	</parm>
69
70	</chapter>
71
72	<!-- Copyright (C) 2008 Torbjorn Sjostrand -->
73